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Baoyuan Guo - One of the best experts on this subject based on the ideXlab platform.
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stereoselectivity in Bioaccumulation and excretion of epoxiconazole by mealworm beetle tenebrio molitor larvae
Ecotoxicology and Environmental Safety, 2014Co-Authors: Xiaotian Lv, Yong Xin Gao, Yaobin Li, Chen Liu, Huili Wang, Jianzhong Li, Baoyuan GuoAbstract:Stereoselectivity in Bioaccumulation and excretion of stereoisomers of epoxiconazole by mealworm beetle (Tenebrio molitor) larvae through dietary exposure was investigated. Liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method that use a ChiralcelOD-3R[cellulosetris-Tris-(3, 5-dichlorophenyl-carbamate)] chromatography column was applied to carry out chiral separation of the stereoisomers. Wheat bran was spiked with racemic epoxiconazole at two dose levels of 20 mg/kg and 2 mg/kg (dry weight) to feed T. molitor larvae. The results showed that both the doses of epoxiconazole were taken up by Tenebrio molitor larvae rapidly at the initial stages. There was a significant trend of stereoselective Bioaccumulation in the larvae with a preferential accumulation of (-)-epoxiconazole in the 20 mg/kg dose. The stereoselectivity in Bioaccumulation in the 2 mg/kg dosage was not obvious compared to the 20 mg/kg group. Results of excretion indicated an active excretion is an important pathway for the larvae to eliminate epoxiconazole which was a passive transport process with non stereoselectivity. The faster elimination might be the reason for the low accumulation of epoxiconazole, as measured by Bioaccumulation Factor (BAF). (C) 2014 Elsevier Inc. All rights reserved.
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Bioaccumulation and excretion of enantiomers of myclobutanil in Tenebrio molitor larvae through dietary exposure.
Chirality, 2013Co-Authors: Xiaotian Lv, Yong Xin Gao, Baoyuan Guo, Yaobin Li, Chen Liu, Huili Wang, Jianzhong LiAbstract:The Bioaccumulation and excretion of enantiomers of myclobutanil in Tenebrio molitor larvae through dietary exposure under laboratory conditions were investigated using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) based on a ChiralcelOD-3R [cellulosetris-tris-(3, 5-dichlorophenyl-carbamate)] column. The wheat bran fed to Tenebrio molitor larvae was spiked with racemic myclobutanil at two dose levels of 20 mg/kg and 2 mg/kg (dry weight). The results showed that there was a significant trend of enantioselective Bioaccumulation in the larvae with a preferential accumulation of (−)-myclobutanil in 20 mg/kg dose exposure, but it was not obviously observed in the 2 mg/kg dose group. A kinetic model considering enantiomerization between the two enantiomers based on first-order reactions was built and the rate constants were estimated to discuss the kinetic reason for the different concentrations of individual enantiomers in the larvae. The approximations implied an inversion between the two enantiomers with a relatively higher rate of the inversion from (−)-myclobutanil to (+)-myclobutanil. Meanwhile, analysis of data of excretion samples suggested the active excretion is probably an important pathway for the insect to eliminate myclobutanil rapidly with nonenantioselectivity as a passive transport process, which was consistent with the low accumulation efficiency of myclobutanil measured by BAF (Bioaccumulation Factor). Chirality 25:890–896, 2013. © 2013 Wiley Periodicals, Inc.
Jon A Arnot - One of the best experts on this subject based on the ideXlab platform.
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use of the Bioaccumulation Factor to screen chemicals for Bioaccumulation potential
Environmental Toxicology and Chemistry, 2012Co-Authors: Jed Costanza, David G Lynch, Robert S Boethling, Jon A ArnotAbstract:The fish bioconcentration Factor (BCF), as calculated from controlled laboratory tests, is commonly used in chemical management programs to screen chemicals for Bioaccumulation potential. The Bioaccumulation Factor (BAF), as calculated from field-caught fish, is more ecologically relevant because it accounts for dietary, respiratory, and dermal exposures. The BCFBAF™ program in the U.S. Environmental Protection Agency's Estimation Programs Interface Suite (EPI Suite™ Ver 4.10) screening-level tool includes the Arnot-Gobas quantitative structure-activity relationship model to estimate BAFs for organic chemicals in fish. Bioaccumulation Factors can be greater than BCFs, suggesting that using the BAF rather than the BCF for screening Bioaccumulation potential could have regulatory and resource implications for chemical assessment programs. To evaluate these potential implications, BCFBAF was used to calculate BAFs and BCFs for 6,034 U.S. high- and medium-production volume chemicals. The results indicate no change in the Bioaccumulation rating for 86% of these chemicals, with 3% receiving lower and 11% receiving higher Bioaccumulation ratings when using the BAF rather than the BCF. All chemicals that received higher Bioaccumulation ratings had log K(OW ) values greater than 4.02, in which a chemical's BAF was more representative of field-based Bioaccumulation than its BCF. Similar results were obtained for 374 new chemicals. Screening based on BAFs provides ecologically relevant results without a substantial increase in resources needed for assessments or the number of chemicals screened as being of concern for Bioaccumulation potential.
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a review of bioconcentration Factor bcf and Bioaccumulation Factor baf assessments for organic chemicals in aquatic organisms
Environmental Reviews, 2006Co-Authors: Jon A ArnotAbstract:Bioaccumulation assessment is important in the scientific evaluation of risks that chemicals may pose to humans and the environment and is a current focus of regulatory effort. The status of Bioaccumulation evaluations for organic chemicals in aquatic systems is reviewed to reduce uncertainty in Bioaccumulation measurement, to provide quality data for assessment, and to assist in model development. A review of 392 scientific literature and database sources includes 5317 bioconcentration Factor (BCF) and 1656 Bioaccumulation Factor (BAF) values measured for 842 organic chemicals in 219 aquatic species. A data quality assessment finds that 45% of BCF values are subject to at least one major source of uncertainty and that measurement errors generally result in an underestimation of actual BCF values. A case study of organic chemicals on the Canadian Domestic Substances List indicates that empirical data are available for less than 4% of the chemicals that require evaluation and of these chemicals, 76% have less than three acceptable quality BCF or BAF values. Field BAFs tend to be greater than laboratory BCFs emphasizing the importance of environmental measurement for reliable assessment; however, only 0.2% of current use organic chemicals have BAF measurements. Key parameters influencing uncertainty and variability in BCF and BAF data are discussed using reviewed data and models. A critical evaluation of representative BCF and BAF models in relation to existing measurements and regulatory criteria in Canada indicate the probability of Type II errors, i.e., false negatives or "misses", using BCF models for Bioaccumulation assessment may be as high as 70.6% depending on the model. Recommendations for the selection of measured and modelled values used in Bioaccumulation assessment are provided, and improvements for the science and regulatory criteria are proposed.
Xiaotian Lv - One of the best experts on this subject based on the ideXlab platform.
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stereoselectivity in Bioaccumulation and excretion of epoxiconazole by mealworm beetle tenebrio molitor larvae
Ecotoxicology and Environmental Safety, 2014Co-Authors: Xiaotian Lv, Yong Xin Gao, Yaobin Li, Chen Liu, Huili Wang, Jianzhong Li, Baoyuan GuoAbstract:Stereoselectivity in Bioaccumulation and excretion of stereoisomers of epoxiconazole by mealworm beetle (Tenebrio molitor) larvae through dietary exposure was investigated. Liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method that use a ChiralcelOD-3R[cellulosetris-Tris-(3, 5-dichlorophenyl-carbamate)] chromatography column was applied to carry out chiral separation of the stereoisomers. Wheat bran was spiked with racemic epoxiconazole at two dose levels of 20 mg/kg and 2 mg/kg (dry weight) to feed T. molitor larvae. The results showed that both the doses of epoxiconazole were taken up by Tenebrio molitor larvae rapidly at the initial stages. There was a significant trend of stereoselective Bioaccumulation in the larvae with a preferential accumulation of (-)-epoxiconazole in the 20 mg/kg dose. The stereoselectivity in Bioaccumulation in the 2 mg/kg dosage was not obvious compared to the 20 mg/kg group. Results of excretion indicated an active excretion is an important pathway for the larvae to eliminate epoxiconazole which was a passive transport process with non stereoselectivity. The faster elimination might be the reason for the low accumulation of epoxiconazole, as measured by Bioaccumulation Factor (BAF). (C) 2014 Elsevier Inc. All rights reserved.
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Bioaccumulation and excretion of enantiomers of myclobutanil in Tenebrio molitor larvae through dietary exposure.
Chirality, 2013Co-Authors: Xiaotian Lv, Yong Xin Gao, Baoyuan Guo, Yaobin Li, Chen Liu, Huili Wang, Jianzhong LiAbstract:The Bioaccumulation and excretion of enantiomers of myclobutanil in Tenebrio molitor larvae through dietary exposure under laboratory conditions were investigated using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) based on a ChiralcelOD-3R [cellulosetris-tris-(3, 5-dichlorophenyl-carbamate)] column. The wheat bran fed to Tenebrio molitor larvae was spiked with racemic myclobutanil at two dose levels of 20 mg/kg and 2 mg/kg (dry weight). The results showed that there was a significant trend of enantioselective Bioaccumulation in the larvae with a preferential accumulation of (−)-myclobutanil in 20 mg/kg dose exposure, but it was not obviously observed in the 2 mg/kg dose group. A kinetic model considering enantiomerization between the two enantiomers based on first-order reactions was built and the rate constants were estimated to discuss the kinetic reason for the different concentrations of individual enantiomers in the larvae. The approximations implied an inversion between the two enantiomers with a relatively higher rate of the inversion from (−)-myclobutanil to (+)-myclobutanil. Meanwhile, analysis of data of excretion samples suggested the active excretion is probably an important pathway for the insect to eliminate myclobutanil rapidly with nonenantioselectivity as a passive transport process, which was consistent with the low accumulation efficiency of myclobutanil measured by BAF (Bioaccumulation Factor). Chirality 25:890–896, 2013. © 2013 Wiley Periodicals, Inc.
Olivier Proux - One of the best experts on this subject based on the ideXlab platform.
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extreme arsenic Bioaccumulation Factor variability in lake titicaca bolivia
Scientific Reports, 2019Co-Authors: Geraldine Sarret, Stephane Guedron, Dario Acha, Sarah Bureau, Florent Arnaudgodet, Delphine Tisserand, Marisol Goniurriza, Claire Gassie, Celine Duwig, Olivier ProuxAbstract:Latin America, like other areas in the world, is faced with the problem of high arsenic (As) background in surface and groundwater, with impacts on human health. We studied As biogeochemical cycling by periphyton in Lake titicaca and the mine-impacted Lake Uru Uru. As concentration was measured in water, sediment, totora plants (Schoenoplectus californicus) and periphyton growing on stems, and As speciation was determined by X-ray absorption spectroscopy in bulk and eDtA-extracted periphyton. Dissolved arsenic was between 5.0 and 15 μg L −1 in Lake Titicaca and reached 78.5 μg L −1 in Lake Uru Uru. As accumulation in periphyton was highly variable. We report the highest As Bioaccumulation Factors ever measured (BAFs periphyton up to 245,000) in one zone of Lake Titicaca, with As present as As(V) and monomethyl-As (MMA(V)). Non-accumulating periphyton found in the other sites presented BAFs periphyton between 1281 and 11,962, with As present as As(III), As(V) and arsenosugars. DNA analysis evidenced several taxa possibly related to this phenomenon. Further screening of bacterial and algal isolates would be necessary to identify the organism(s) responsible for As hyperaccumulation. Impacts on the ecosystem and human health appear limited, but such organisms or consortia would be of great interest for the treatment of As contaminated water. The arsenic (As) geogenic background of surface and groundwater is naturally high in South America, predominantly originating from young volcanic rocks and their weathering products in arid oxidizing conditions 1-4. As a result, about 4.5 million people in South America are chronically exposed to high levels of As (>50 µg L −1) 5 , and certain Andean populations have developed a unique capacity to adapt to As toxicity 6,7. Concerning Andean lakes, extreme As concentrations are observed in hypersaline lakes colonized by extremophile bacterial communities 8 , and lower but still significant concentrations are observed in other, less saline lakes, which are major freshwater resources 5. In many areas of the Altiplano, mining and smelting activities add to natural rock weathering processes in the As budget 9. The biogeochemical cycling of As has been studied in freshwater and marine ecosystems, and in hypersaline environments, but its trophic transfer and speciation in living organisms mainly concerns the marine environment and As contaminated freshwater systems 10. In the high altitude lakes of the Andean Altiplano (above 3500 m asl), shallow zones (<2 m) are colonized by totoras (Schoenoplectus californicus, syn Scirpus californicus). These macrophytes were used for construction purposes in traditional Andean culture. Nowadays, they are mainly used as cattle fodder and have been tested successfully in constructed wetlands in North America for the removal of metals (Zn, Cu, Cd, Pb) and nutrients from wastewater 11-14. The filtration potential of wetland plants does not rely on absorption by the plant, but on physico-chemical and biologically driven processes taking place on submerged stems and in the rhizosphere 15,16. In particular, the periphyton, an assemblage of algae and bacteria forming a
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Extreme Arsenic Bioaccumulation Factor Variability in Lake Titicaca, Bolivia.
Scientific Reports, 2019Co-Authors: Geraldine Sarret, Stephane Guedron, Dario Acha, Sarah Bureau, Delphine Tisserand, Claire Gassie, Celine Duwig, Florent Arnaud-godet, Marisol Goñi-urriza, Olivier ProuxAbstract:Latin America, like other areas in the world, is faced with the problem of high arsenic (As) background in surface and groundwater, with impacts on human health. We studied As biogeochemical cycling by periphyton in Lake titicaca and the mine-impacted Lake Uru Uru. As concentration was measured in water, sediment, totora plants (Schoenoplectus californicus) and periphyton growing on stems, and As speciation was determined by X-ray absorption spectroscopy in bulk and eDtA-extracted periphyton. Dissolved arsenic was between 5.0 and 15 μg L −1 in Lake Titicaca and reached 78.5 μg L −1 in Lake Uru Uru. As accumulation in periphyton was highly variable. We report the highest As Bioaccumulation Factors ever measured (BAFs periphyton up to 245,000) in one zone of Lake Titicaca, with As present as As(V) and monomethyl-As (MMA(V)). Non-accumulating periphyton found in the other sites presented BAFs periphyton between 1281 and 11,962, with As present as As(III), As(V) and arsenosugars. DNA analysis evidenced several taxa possibly related to this phenomenon. Further screening of bacterial and algal isolates would be necessary to identify the organism(s) responsible for As hyperaccumulation. Impacts on the ecosystem and human health appear limited, but such organisms or consortia would be of great interest for the treatment of As contaminated water. The arsenic (As) geogenic background of surface and groundwater is naturally high in South America, predominantly originating from young volcanic rocks and their weathering products in arid oxidizing conditions 1-4. As a result, about 4.5 million people in South America are chronically exposed to high levels of As (>50 µg L −1) 5 , and certain Andean populations have developed a unique capacity to adapt to As toxicity 6,7. Concerning Andean lakes, extreme As concentrations are observed in hypersaline lakes colonized by extremophile bacterial communities 8 , and lower but still significant concentrations are observed in other, less saline lakes, which are major freshwater resources 5. In many areas of the Altiplano, mining and smelting activities add to natural rock weathering processes in the As budget 9. The biogeochemical cycling of As has been studied in freshwater and marine ecosystems, and in hypersaline environments, but its trophic transfer and speciation in living organisms mainly concerns the marine environment and As contaminated freshwater systems 10. In the high altitude lakes of the Andean Altiplano (above 3500 m asl), shallow zones (
Robert S Boethling - One of the best experts on this subject based on the ideXlab platform.
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use of the Bioaccumulation Factor to screen chemicals for Bioaccumulation potential
Environmental Toxicology and Chemistry, 2012Co-Authors: Jed Costanza, David G Lynch, Robert S Boethling, Jon A ArnotAbstract:The fish bioconcentration Factor (BCF), as calculated from controlled laboratory tests, is commonly used in chemical management programs to screen chemicals for Bioaccumulation potential. The Bioaccumulation Factor (BAF), as calculated from field-caught fish, is more ecologically relevant because it accounts for dietary, respiratory, and dermal exposures. The BCFBAF™ program in the U.S. Environmental Protection Agency's Estimation Programs Interface Suite (EPI Suite™ Ver 4.10) screening-level tool includes the Arnot-Gobas quantitative structure-activity relationship model to estimate BAFs for organic chemicals in fish. Bioaccumulation Factors can be greater than BCFs, suggesting that using the BAF rather than the BCF for screening Bioaccumulation potential could have regulatory and resource implications for chemical assessment programs. To evaluate these potential implications, BCFBAF was used to calculate BAFs and BCFs for 6,034 U.S. high- and medium-production volume chemicals. The results indicate no change in the Bioaccumulation rating for 86% of these chemicals, with 3% receiving lower and 11% receiving higher Bioaccumulation ratings when using the BAF rather than the BCF. All chemicals that received higher Bioaccumulation ratings had log K(OW ) values greater than 4.02, in which a chemical's BAF was more representative of field-based Bioaccumulation than its BCF. Similar results were obtained for 374 new chemicals. Screening based on BAFs provides ecologically relevant results without a substantial increase in resources needed for assessments or the number of chemicals screened as being of concern for Bioaccumulation potential.
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improved method for estimating bioconcentration Bioaccumulation Factor from octanol water partition coefficient
Environmental Toxicology and Chemistry, 1999Co-Authors: William M Meylan, Robert S Boethling, Philip H Howard, Dallas Aronson, Heather Printup, Sybil GouchieAbstract:A compound's bioconcentration Factor (BCF) is the most commonly used indicator of its tendency to accumulate in aquatic organisms from the surrounding medium. Because it is expensive to measure, the BCF is generally estimated from the octanol/water partition coefficient (Kow), but currently used regression equations were developed from small data sets that do not adequately represent the wide range of chemical substances now subject to review. To develop an improved method, we collected BCF data in a file that contained information on measured BCFs and other key experimental details for 694 chemicals. Log BCF was then regressed against log Kow and chemicals with significant deviations from the line of best fit were analyzed by chemical structure. The resulting algorithm classifies a substance as either nonionic or ionic, the latter group including carboxylic acids, sulfonic acids and their salts, and quaternary N compounds. Log BCF for nonionics is estimated from log Kow and a series of correction Factors if applicable; different equations apply for log Kow 1.0 to 7.0 and >7.0. For ionics, chemicals are categorized by log Kow and a log BCF in the range 0.5 to 1.75 is assigned. Organometallics, nonionics with long alkyl chains, and aromatic azo compounds receive special treatment. The correlation coefficient (r2 = 0.73) and mean error (0.48) for log BCF (n = 694) indicate that the new method is a significantly better fit to existing data than other methods.
