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Meyer C, Stravs MA, Hollender J. How Wastewater Reflects Human Metabolism─Suspect Screening of Pharmaceutical Metabolites in Wastewater Influent. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9828-9839. [PMID: 38785362 PMCID: PMC11154963 DOI: 10.1021/acs.est.4c00968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/13/2024] [Accepted: 04/17/2024] [Indexed: 05/25/2024]
Abstract
Pharmaceuticals and their human metabolites are contaminants of emerging concern in the aquatic environment. Most monitoring studies focus on a limited set of parent compounds and even fewer metabolites. However, more than 50% of the most consumed pharmaceuticals are excreted in higher amounts as metabolites than as parents, as confirmed by a literature analysis within this study. Hence, we applied a wide-scope suspect screening approach to identify human pharmaceutical metabolites in wastewater influent from three Swiss treatment plants. Based on consumption amounts and human metabolism data, a suspect list comprising 268 parent compounds and over 1500 metabolites was compiled. Online solid phase extraction combined with liquid chromatography coupled to high-resolution tandem mass spectrometry was used to analyze the samples. Data processing, annotation, and structure elucidation were achieved with various tools, including molecular networking as well as SIRIUS/CSI:FingerID and MetFrag for MS2 spectra rationalization. We confirmed 37 metabolites with reference standards and 16 by human liver S9 incubation experiments. More than 25 metabolites were detected for the first time in influent wastewater. Semiquantification with MS2Quant showed that metabolite to parent concentration ratios were generally lower compared to literature expectations, probably due to further metabolite transformation in the sewer system or limitations in the metabolite detection. Nonetheless, metabolites pose a large fraction to the total pharmaceutical contribution in wastewater, highlighting the need for metabolite inclusion in chemical risk assessment.
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Affiliation(s)
- Corina Meyer
- Eawag:
Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
- Institute
of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitaetstrasse
16, 8092 Zurich, Switzerland
| | - Michael A. Stravs
- Eawag:
Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
| | - Juliane Hollender
- Eawag:
Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600 Duebendorf, Switzerland
- Institute
of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitaetstrasse
16, 8092 Zurich, Switzerland
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2
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Zercher M, Coral JA, Nabb D, Powers G, Jones A, Johanning K. A Comparison of In Vitro Metabolic Clearance of Various Regulatory Fish Species Using Hepatic S9 Fractions. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2024; 43:1390-1405. [PMID: 38652000 DOI: 10.1002/etc.5866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/04/2023] [Accepted: 03/08/2024] [Indexed: 04/25/2024]
Abstract
Bioaccumulation predictions can be substantially improved by combining in vitro metabolic rate measurements derived from rainbow trout hepatocytes and/or hepatic S9 fractions with quantitative structure-activity relationship (QSAR) modeling approaches. Compared with in vivo testing guidelines Organisation for Economic Co-operation and Development (OECD) 305 and Office of Chemical Safety and Pollution Prevention (OCSPP; an office of the US Environmental Protection Agency) 850.1730, the recently adopted OECD test guidelines 319A and 319B are in vitro approaches that have the potential to provide a time- and cost-efficient, humane solution, reducing animal use while addressing uncertainties in bioaccumulation across species. The present study compares the hepatic clearance of the S9 subcellular fraction of rainbow trout, bluegill, common carp, fathead minnow, and largemouth bass, discerning potential differences in metabolism between different warm- and cold-water species. With refinements to the in vitro metabolic S9 assay for high-throughput analysis, we measured in vitro clearance rates of seven chemicals crossing multiple classes of chemistry and modes of action. We confirmed that data from rainbow trout liver S9 fraction metabolic rates can be utilized to predict rainbow trout bioconcentration factors using an in vitro to in vivo extrapolation model, as intended in the OECD 319B applicability domain per the bioaccumulation prediction. Also, we determined that OECD 319B can be applied to other species, modified according to their habitat, adaptations to feeding behavior, and environmental conditions (e.g., temperature). Once toxicokinetics for each species is better understood and appropriate models are developed, this method can be an excellent tool to determine hepatic clearance and potential bioaccumulation across species. The present study could be leveraged prior to or in place of initiating in vivo bioconcentration studies, thus optimizing selection of appropriate fish species. Environ Toxicol Chem 2024;43:1390-1405. © 2024 SETAC.
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Affiliation(s)
| | | | - Diane Nabb
- FMC Agricultural Solutions, Newark, Delaware, USA
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3
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Franco ME, Schönenberger R, Hollender J, Schirmer K. Organ-specific biotransformation in salmonids: Insight into intrinsic enzyme activity and biotransformation of three micropollutants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 925:171769. [PMID: 38499104 DOI: 10.1016/j.scitotenv.2024.171769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/25/2024] [Accepted: 03/15/2024] [Indexed: 03/20/2024]
Abstract
Aquatic ecosystems continue to be threatened by chemical pollution. To what extent organisms are able to cope with chemical exposure depends on their ability to display mechanisms of defense across different organs. Among these mechanisms, biotransformation processes represent key physiological responses that facilitate detoxification and reduce the bioaccumulation potential of chemicals. Biotransformation does not only depend on the ability of different organs to display biotransformation enzymes but also on the affinity of chemicals towards these enzymes. In the present study, we explored the ability of different organs and of two freshwater fish to support biotransformation processes through the determination of in vitro phase I and II biotransformation enzyme activity, and their role in supporting intrinsic clearance and the formation of biotransformation products. Three environmentally relevant pollutants were evaluated: the polycyclic aromatic hydrocarbon (PAH) pyrene (as recommended by the OECD 319b test guideline), the fungicide azoxystrobin, and the pharmaceutical propranolol. Comparative studies using S9 sub-cellular fractions derived from the liver, intestine, gills, and brain of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) revealed significant phase I and II enzyme activity in all organs. However, organ- and species-specific differences were found. In brown trout, significant extrahepatic biotransformation was observed for pyrene but not for azoxystrobin and propranolol. In rainbow trout, the brain appeared to biotransform azoxystrobin. In this same species, propranolol appeared to be biotransformed by the intestine and gills. Biotransformation products could be detected only from hepatic biotransformation, and their profiles and formation rates displayed species-specific patterns and occurred at different magnitudes. Altogether, our findings further contribute to the current understanding of organ-specific biotransformation capacity, beyond the expression and activity of enzymes, and its dependence on specific enzyme-chemical interactions to support mechanisms of defense against exposure.
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Affiliation(s)
- Marco E Franco
- Department of Environmental Toxicology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland
| | - René Schönenberger
- Department of Environmental Toxicology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland
| | - Juliane Hollender
- Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland; Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland
| | - Kristin Schirmer
- Department of Environmental Toxicology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, 8600 Dübendorf, Switzerland; Department of Environmental Systems Science, ETH Zürich, 8092 Zürich, Switzerland; School of Architecture, Civil and Environmental Engineering, EPF Lausanne, 1015 Lausanne, Switzerland.
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4
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Laue H, Hostettler L, Jenner KJ, Sanders G, Natsch A. Bioconcentration Assessment in Fish Based on In Vitro Intrinsic Clearance: Predictivity of an Empirical Model Compared to In Vitro-In Vivo Extrapolation Models. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:13325-13335. [PMID: 37643004 DOI: 10.1021/acs.est.3c02216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
To estimate the bioconcentration factor (BCF), the in vitro intrinsic clearance (CLIN VITRO,INT) from rainbow trout liver S9 fractions (RT-S9) can be applied to in vitro-in vivo extrapolation (IVIVE) models, yet uncertainties remain in model parameterization. An alternative model approach is evaluated: a regression model was built in the form log BCF = a × log Kow + b × log CLIN VITRO,INT. The coefficients a and b were fitted based on a training set of 40 chemicals. A high robustness of the coefficients and good accuracy of BCF prediction were found on independent datasets of neutral organic chemicals (measured log Kow 3.3-6.2). BCF predictions were similar to or in better agreement with in vivo BCFs compared to IVIVE models (2.4- to 2.9- vs 2.8- to 3.6-fold misprediction) for training and test sets. Species-matched models (trout, carp) did not result in improvements. This study presents the largest dataset on CLIN VITRO,INT and BCFs to assess predictivity of the RT-S9 assay. The robustness of the regression statistics on different datasets and the high statistical weight of the CLIN VITRO,INT term illustrate the predictive power of the RT-S9 assay as an important step toward regulatory acceptance to replace animal experiments.
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Affiliation(s)
- Heike Laue
- Fragrances S&T, Givaudan Schweiz AG, Kemptthal 8310, Switzerland
| | - Lu Hostettler
- Fragrances S&T, Givaudan Schweiz AG, Kemptthal 8310, Switzerland
| | - Karen J Jenner
- Regulatory Affairs & Product Safety, Fragrance & Beauty, Givaudan UK Ltd, Ashford, Kent, TN24 OLT, United Kingdom
| | - Gordon Sanders
- Regulatory Affairs & Product Safety, Fragrance & Beauty, Givaudan International SA,Vernier 1214, Switzerland
| | - Andreas Natsch
- Fragrances S&T, Givaudan Schweiz AG, Kemptthal 8310, Switzerland
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5
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Bischof I, Arnot JA, Jürling H, Knipschild G, Schlechtriem C, Schauerte A, Segner H. In vitro biotransformation assays using fish liver cells: Comparing rainbow trout and carp hepatocytes. FRONTIERS IN TOXICOLOGY 2022; 4:1021880. [PMID: 36211196 PMCID: PMC9538944 DOI: 10.3389/ftox.2022.1021880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/05/2022] [Indexed: 11/23/2022] Open
Abstract
Biotransformation assays using primary hepatocytes from rainbow trout, Oncorhynchus mykiss, were validated as a reliable in vitro tool to predict in vivo bioconcentration factors (BCF) of chemicals in fish. Given the pronounced interspecies differences of chemical biotransformation, the present study aimed to compare biotransformation rate values and BCF predictions obtained with hepatocytes from the cold-water species, rainbow trout, to data obtained with hepatocytes of the warm-water species, common carp (Cyprinus carpio). In a first step, we adapted the protocol for the trout hepatocyte assay, including the cryopreservation method, to carp hepatocytes. The successful adaptation serves as proof of principle that the in vitro hepatocyte biotransformation assays can be technically transferred across fish species. In a second step, we compared the in vitro intrinsic clearance rates (CLin vitro, int) of two model xenobiotics, benzo[a]pyrene (BaP) and methoxychlor (MXC), in trout and carp hepatocytes. The in vitro data were used to predict in vivo biotransformation rate constants (kB) and BCFs, which were then compared to measured in vivo kB and BCF values. The CLin vitro, int values of BaP and MXC did not differ significantly between trout and carp hepatocytes, but the predicted BCF values were significantly higher in trout than in carp. In contrast, the measured in vivo BCF values did not differ significantly between the two species. A possible explanation of this discrepancy is that the existing in vitro-in vivo prediction models are parameterized only for trout but not for carp. Therefore, future research needs to develop species-specific extrapolation models.
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Affiliation(s)
- Ina Bischof
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany
- Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
- *Correspondence: Ina Bischof,
| | - Jon A. Arnot
- Department of Physical & Environmental Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- ARC Arnot Research and Consulting, Toronto, ON, Canada
| | - Heinrich Jürling
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany
| | - Georg Knipschild
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany
| | | | - Anna Schauerte
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany
| | - Helmut Segner
- Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
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6
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Ribbenstedt A, Armitage JM, Günther F, Arnot JA, Droge STJ, McLachlan MS. In Vivo Bioconcentration of 10 Anionic Surfactants in Rainbow Trout Explained by In Vitro Data on Partitioning and S9 Clearance. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:6305-6314. [PMID: 35467837 PMCID: PMC9118553 DOI: 10.1021/acs.est.1c05543] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Bioconcentration factors (BCFs) in rainbow trout were measured for 10 anionic surfactants with a range of alkyl chain lengths and different polar head groups. The BCFs ranged from 0.04 L kg-1 ww (for C10SO3) to 1370 L kg-1 ww (C16SO3). There was a strong correlation between the log BCF and log membrane lipid-water distribution ratio (DMLW, r2 = 0.96), and biotransformation was identified as the dominant elimination mechanism. The strong positive influence of DMLW on BCF was attributed to two phenomena: (i) increased partitioning from water into the epithelial membrane of the gill, leading to more rapid diffusion across this barrier and more rapid uptake, and (ii) increased sequestration of the surfactant body burden into membranes and other body tissues, resulting in lower freely dissolved concentrations available for biotransformation. Estimated whole-body in vivo biotransformation rate constants kB-BCF are within a factor three of rate constants estimated from S9 in vitro assays for six of the eight test chemicals for which kB-BCF could be determined. A model-based assessment indicated that the hepatic clearance rate of freely dissolved chemicals was similar for the studied surfactants. The dataset will be useful for evaluation of in silico and in vitro methods to assess bioaccumulation.
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Affiliation(s)
- Anton Ribbenstedt
- Department
of Environmental Science, Stockholm University, 106 91 Stockholm, Sweden
| | - James M. Armitage
- AES
Armitage Environmental Sciences, Inc., Ottawa, Ontario K1L 8C3, Canada
| | - Felix Günther
- Department
of Mathematics, Stockholm University, 106 91 Stockholm, Sweden
| | - Jon A. Arnot
- ARC
Arnot Research and Consulting Inc., Toronto, Ontario M4M 1W4, Canada
- Department
of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Steven T. J. Droge
- Institute
for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, 1090 GE Amsterdam, The Netherlands
| | - Michael S. McLachlan
- Department
of Environmental Science, Stockholm University, 106 91 Stockholm, Sweden
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7
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Droge STJ, Scherpenisse P, Arnot JA, Armitage JM, McLachlan MS, Ohe PCVD, Hodges G. Screening the baseline fish bioconcentration factor of various types of surfactants using phospholipid binding data. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1930-1948. [PMID: 34787154 DOI: 10.1039/d1em00327e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Fish bioconcentration factors (BCFs) are commonly used in chemical hazard and risk assessment. For neutral organic chemicals BCFs are positively correlated with the octanol-water partition ratio (KOW), but KOW is not a reliable parameter for surfactants. Membrane lipid-water distribution ratios (DMLW) can be accurately measured for all kinds of surfactants, using phospholipid-based sorbents. This study first demonstrates that DMLW values for ionic surfactants are more than 100 000 times higher than the partition ratio to fish-oil, representing neutral storage lipid. A non-ionic alcohol ethoxylate surfactant showed almost equal affinity for both lipid types. Accordingly, a baseline screening BCF value for surfactants (BCFbaseline) can be approximated for ionic surfactants by multiplying DMLW by the phospholipid fraction in tissue, and for non-ionic surfactants by multiplying DMLW by the total lipid fraction. We measured DMLW values for surfactant structures, including linear and branched alkylbenzenesulfonates, an alkylsulfoacetate and an alkylethersulfate, bis(2-ethylhexyl)-surfactants (e.g., docusate), zwitterionic alkylbetaines and alkylamine-oxides, and a polyprotic diamine. Together with sixty previously published DMLW values for surfactants, structure-activity relationships were derived to elucidate the influence of surfactant specific molecular features on DMLW. For 23 surfactant types, we established the alkyl chain length at which BCFbaseline would exceed the EU REACH bioaccumulation (B) threshold of 2000 L kg-1, and would therefore require higher tier assessments to further refine the BCF estimate. Finally, the derived BCFbaseline are compared with measured literature in vivo BCF data where available, suggesting that refinements, most notably reliable estimates of biotransformation rates, are needed for most surfactant types.
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Affiliation(s)
- Steven T J Droge
- Institute for Biodiversity and Ecosystem Dynamics, Department Freshwater and Marine Ecology, University of Amsterdam, The Netherlands.
| | - Peter Scherpenisse
- Institute for Risk Assessment Sciences, Utrecht University, The Netherlands
| | - Jon A Arnot
- ARC Arnot Research and Consulting, Toronto, Ontario, Canada
| | | | | | | | - Geoff Hodges
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
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8
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Droge ST, Armitage JM, Arnot JA, Fitzsimmons PN, Nichols JW. Biotransformation Potential of Cationic Surfactants in Fish Assessed with Rainbow Trout Liver S9 Fractions. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:3123-3136. [PMID: 34379820 PMCID: PMC9187044 DOI: 10.1002/etc.5189] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/10/2021] [Accepted: 08/05/2021] [Indexed: 05/13/2023]
Abstract
Biotransformation may substantially reduce the extent to which organic environmental contaminants accumulate in fish. Presently, however, relatively little is known regarding the biotransformation of ionized chemicals, including cationic surfactants, in aquatic organisms. To address this deficiency, a rainbow trout liver S9 substrate depletion assay (RT-S9) was used to measure in vitro intrinsic clearance rates (CLint ; ml min-1 g liver-1 ) for 22 cationic surfactants that differ with respect to alkyl chain length and degree of methylation on the charged nitrogen atom. None of the quaternary N,N,N-trimethylalkylammonium compounds exhibited significant clearance. Rapid clearance was observed for N,N-dimethylalkylamines, and slower rates of clearance were measured for N-methylalkylamine analogs. Clearance rates for primary alkylamines were generally close to or below detectable levels. For the N-methylalkylamines and N,N-dimethylalkylamines, the highest CLint values were measured for C10 -C12 homologs; substantially lower clearance rates were observed for homologs containing shorter or longer carbon chains. Based on its cofactor dependency, biotransformation of C12 -N,N-dimethylamine appears to involve one or more cytochrome P450-dependent reaction pathways, and sulfonation. On a molar basis, N-demethylation metabolites accounted for up to 25% of the N,N-dimethylalkylamines removed during the 2-h assay, and up to 55% of the removed N-methylalkylamines. These N-demethylation products possess greater metabolic stability in the RT-S9 assay than the parent structures from which they derive and may contribute to the overall risk of ionizable alkylamines. The results of these studies provide a set of consistently determined CLint values that may be extrapolated to whole trout to inform in silico bioaccumulation assessments. Environ Toxicol Chem 2021;40:3123-3136. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Steven T.J. Droge
- Institute for Biodiversity and Ecosystem DynamicsUniversity of AmsterdamAmsterdamThe Netherlands
| | | | - Jon A. Arnot
- ARC Arnot Research and ConsultingTorontoOntarioCanada
| | - Patrick N. Fitzsimmons
- Great Lakes Toxicology and Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and DevelopmentUS Environmental Protection AgencyDuluthMinnesota
| | - John W. Nichols
- Great Lakes Toxicology and Ecology Division, National Health and Environmental Effects Research Laboratory, Office of Research and DevelopmentUS Environmental Protection AgencyDuluthMinnesota
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9
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Huber C, Müller E, Schulze T, Brack W, Krauss M. Improving the Screening Analysis of Pesticide Metabolites in Human Biomonitoring by Combining High-Throughput In Vitro Incubation and Automated LC-HRMS Data Processing. Anal Chem 2021; 93:9149-9157. [PMID: 34161736 DOI: 10.1021/acs.analchem.1c00972] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
There is a current need to monitor human exposure to a large number of pesticides and other chemicals of emerging concern (CECs). This requires screening analysis with high confidence for these compounds and their metabolites in complex matrices, which is hampered by the fact that no reference standards are available for most metabolites. We address this challenge by a high-throughput workflow based on incubation of pesticides (or other CECs) with human liver S9, followed by solid-phase extraction, liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis, and automated data processing to generate a database (retention time, precursor m/z, and MS2 spectral library) for the annotation in human samples. The metabolite prioritization consists of statistical comparisons and mass defect and m/z range filtering to obtain a subset of probable phase I metabolites, for which molecular formulas and likely metabolic transformation are retrieved. We tested the workflow on 22 pesticides, for which we could determine 91 metabolite molecular formulas which are only partly covered by the literature and/or predicted by in silico metabolization. Our workflow allows for an efficient generation of metabolite reference information, which can be used directly for annotating LC-HRMS data from human samples. A full structure elucidation of individual metabolites can be limited to those being actually present in human samples.
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Affiliation(s)
- Carolin Huber
- Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany.,Institute of Ecology, Diversity and Evolution, Goethe University Frankfurt Biologicum, Campus Riedberg, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany
| | - Erik Müller
- Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany.,Institute of Ecology, Diversity and Evolution, Goethe University Frankfurt Biologicum, Campus Riedberg, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany
| | - Tobias Schulze
- Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Werner Brack
- Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany.,Institute of Ecology, Diversity and Evolution, Goethe University Frankfurt Biologicum, Campus Riedberg, Max-von-Laue-Str. 13, 60438 Frankfurt am Main, Germany
| | - Martin Krauss
- Department of Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany
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10
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Nichols JW, Hoffman AD, Swintek JA, Droge ST, Fitzsimmons PN. Addition of Phenylmethylsulfonyl Fluoride Increases the Working Lifetime of the Trout Liver S9 Substrate Depletion Assay, Resulting in Improved Detection of Low Intrinsic Clearance Rates. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:148-161. [PMID: 33045099 PMCID: PMC7901806 DOI: 10.1002/etc.4901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/14/2020] [Accepted: 10/07/2020] [Indexed: 05/11/2023]
Abstract
The activity of a trout liver S9 substrate depletion assay has been shown to decline over time, presumably due to proteolytic degradation of biotransformation enzymes. To address this problem, assay performance was evaluated following the addition of phenylmethylsulfonyl fluoride (PMSF) or a general-purpose protease inhibitor cocktail to liver homogenization buffers and/or S9 reaction mixtures. Addition of PMSF to liver homogenization buffers and/or S9 reaction mixtures had little or no effect on clearance of phenanthrene, a model cytochrome P450 substrate, in short-term (25 or 30 min) depletion experiments but resulted in significant improvements in retention of this initial activity over time. The protease inhibitor cocktail strongly inhibited initial activity when added to homogenization buffers or reaction mixtures. Taking into consideration potential effects on liver carboxylesterases, the treatment approach determined to be optimal was addition of 10 µM PMSF to the S9 reaction mixture. Addition of 10 µM PMSF to the mixture resulted in significantly higher rates of phenanthrene clearance in 2-h incubations relative to those obtained in the absence of PMSF and a 6-fold increase in the working lifetime of the preparation. The results of a statistical power analysis suggest that by increasing the working lifetime of the assay, addition of PMSF to the reaction mixture could result in substantially improved detection of low in vitro clearance rates when compared to current practice. These findings demonstrate the value of adding PMSF to the trout S9 preparation and may have broad implications for use of this assay to support chemical bioaccumulation assessments for fish. Environ Toxicol Chem 2021;40:148-161. © 2020 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- John W. Nichols
- US Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, Minnesota, USA
- Address correspondence to
| | - Alex D. Hoffman
- US Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, Minnesota, USA
| | | | - Steven T.J. Droge
- Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, Universiteit van Amsterdam, Amsterdam, NL
| | - Patrick N. Fitzsimmons
- US Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, Minnesota, USA
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11
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Kropf C, Begnaud F, Gimeno S, Berthaud F, Debonneville C, Segner H. In Vitro Biotransformation Assays Using Liver S9 Fractions and Hepatocytes from Rainbow Trout (Oncorhynchus mykiss): Overcoming Challenges with Difficult to Test Fragrance Chemicals. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2020; 39:2396-2408. [PMID: 32915480 DOI: 10.1002/etc.4872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/02/2020] [Accepted: 09/08/2020] [Indexed: 06/11/2023]
Abstract
In vitro metabolic stability assays using rainbow trout (Oncorhynchus mykiss) isolated hepatocytes (RT-HEP) or hepatic S9 fractions (RT-S9) were introduced to provide biotransformation rate data for the assessment of chemical bioaccumulation in fish. The present study explored the suitability of the RT-HEP and RT-S9 assays for difficult test chemicals, and the in vitro-based predictions were compared to in silico-based predictions and in vivo-measured bioconcentration factors (BCFs). The results show that volatile or reactive chemicals can be tested with minor modifications of the in vitro protocols. For hydrophobic chemicals, a passive dosing technique was developed. Finally, a design-of-experiment approach was used to identify optimal in vitro assay conditions. The modified assay protocols were applied to 10 fragrances with diverse physicochemical properties. The in vitro intrinsic clearance rates were higher in the S9 than in the hepatocyte assay, but the in vitro-in vivo (IVIV) predictions were comparable between the 2 assays. The IVIV predictions classified the test chemicals as nonbioaccumulative (BCF < 2000), which was in agreement with the in vivo data but in contrast to the in silico-based predictions. The findings from the present study provide strong evidence that the RT-HEP and RT-S9 assays can provide reliable estimates of in vivo biotransformation rates for test chemicals with difficult physicochemical properties. Environ Toxicol Chem 2020;39:2396-2408. © 2020 SETAC.
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Affiliation(s)
- Christian Kropf
- Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Frédéric Begnaud
- Corporate R&D Division/Analytical Innovation, Firmenich International, Geneva, Switzerland
| | - Sylvia Gimeno
- Legal and Compliance, Firmenich Belgium, Louvain-La-Neuve, Belgium
| | - Fabienne Berthaud
- Corporate R&D Division/Analytical Innovation, Firmenich International, Geneva, Switzerland
| | - Christian Debonneville
- Corporate R&D Division/Analytical Innovation, Firmenich International, Geneva, Switzerland
| | - Helmut Segner
- Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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12
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Saunders LJ, Fitzsimmons PN, Nichols JW, Gobas FAPC. In vitro-in vivo extrapolation of hepatic and gastrointestinal biotransformation rates of hydrophobic chemicals in rainbow trout. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 228:105629. [PMID: 33002683 PMCID: PMC7962060 DOI: 10.1016/j.aquatox.2020.105629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 08/24/2020] [Accepted: 09/05/2020] [Indexed: 06/11/2023]
Abstract
Hepatic in vitro biotransformation assays, in combination with in vitro-in vivo extrapolation (IVIVE) and bioaccumulation modeling, can be used to support regulatory bioaccumulation assessments. In most applications, however, these methods ignore the possibility of extrahepatic metabolism. Here we evaluated intestinal biotransformation in rainbow trout using S9 fractions prepared from the upper intestinal (GIT) epithelium. Measured levels of activity determined using standard substrates for phase I and phase II biotransformation enzymes were within 2-fold of activities measured in hepatic S9 fractions. In vitro intrinsic clearance rates for 2-ethylhexyl-4-methoxycinnamate (EHMC; an organic sunscreen agent) and two polycyclic aromatic hydrocarbons (pyrene [PYR] and benzo(a)pyrene [BAP]) were significantly higher in liver S9 fractions than in GIT S9 fractions. For octocrylene (OCT; a second sunscreen agent), however, in vitro intrinsic clearance rates were higher in GIT S9 fractions compared to liver S9 fractions. An existing 'liver only' IVIVE model was expanded to consider biotransformation in both the liver and GIT. Relevant IVIVE scaling factors were developed by morphological, histological, and biochemical evaluation of trout intestines. For chemicals biotransformed at higher rates by hepatic S9 fractions (i.e., BAP, PYR, EHMC), the 'liver & GIT' model yielded whole-body biotransformation rate constants (kMET) that were within 1.2 to 1.4-fold of those estimated using the 'liver only' model. In contrast to these findings, the mean kMET for OCT obtained using the 'liver & GIT' model was 3.3 times higher than the mean kMET derived using the 'liver only' model and was in good agreement with empirical kMET estimates determined previously for trout (<20 % difference). The results of this study suggest that current 'liver only' IVIVE approaches may underestimate in vivo biotransformation rates for chemicals that undergo substantial biotransformation in the GIT.
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Affiliation(s)
- Leslie J Saunders
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | - John W Nichols
- United States Environmental Protection Agency, Duluth, MN, USA
| | - Frank A P C Gobas
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada; School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia, Canada.
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13
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Laue H, Hostettler L, Badertscher RP, Jenner KJ, Sanders G, Arnot JA, Natsch A. Examining Uncertainty in In Vitro-In Vivo Extrapolation Applied in Fish Bioconcentration Models. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:9483-9494. [PMID: 32633948 DOI: 10.1021/acs.est.0c01492] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In vitro biotransformation rates were determined for 30 chemicals, mostly fragrance ingredients, using trout liver S9 fractions (RT-S9) and incorporated into in vitro-in vivo extrapolation (IVIVE) models to predict bioconcentration factors (BCFs). Predicted BCFs were compared against empirical BCFs to explore potential major uncertainties involved in the in vitro methods and IVIVE models: (i) in vitro chemical test concentrations; (ii) different gill uptake rate constant calculations (k1); (iii) protein binding (different calculations and measurement of the fraction of unbound chemical, fU); (iv) species differences; and (v) extrahepatic biotransformation. Predicted BCFs were within 0.5 log units for 44% of the chemicals compared to empirical BCFs, whereas 56% were overpredicted by >0.5 log units. This trend of overprediction was reduced by alternative k1 calculations to 32% of chemicals being overpredicted. Moreover, hepatic in vitro rates scaled to whole body biotransformation rates (kB) were compared against in vivo kB estimates. In vivo kB was underestimated for 79% of the chemicals. Neither lowering the test concentration, nor incorporation of new measured fU values, nor species matching avoided the tendency to overpredict BCFs indicating that further improvements to the IVIVE models are needed or extrahepatic biotransformation plays an underestimated role.
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Affiliation(s)
- Heike Laue
- Givaudan Schweiz AG, Fragrances S&T, 8310 Kemptthal, Switzerland
| | - Lu Hostettler
- Givaudan Schweiz AG, Fragrances S&T, 8310 Kemptthal, Switzerland
| | | | - Karen J Jenner
- Givaudan UK Ltd, Regulatory Affairs and Product Safety, Ashford, Kent TN24 OLT, United Kingdom
| | - Gordon Sanders
- Givaudan International SA, Regulatory Affairs and Product Safety, 1214 Vernier, Switzerland
| | - Jon A Arnot
- ARC Arnot Research and Consulting, Toronto, Ontario M4M 1W4, Canada
| | - Andreas Natsch
- Givaudan Schweiz AG, Fragrances S&T, 8310 Kemptthal, Switzerland
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14
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Weeks J, Guiney P, Johanning K. In vitro and in vivo metabolic stability of various fragrance materials and insect repellent in rainbow trout (
Oncorhynchus mykiss
). J Appl Toxicol 2020; 40:763-779. [DOI: 10.1002/jat.3942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 12/19/2019] [Accepted: 12/21/2019] [Indexed: 11/10/2022]
Affiliation(s)
- John Weeks
- SC Johnson and Son, Inc. Racine Wisconsin
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15
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Nichols JW, Ladd MA, Hoffman AD, Fitzsimmons PN. Biotransformation of Polycyclic Aromatic Hydrocarbons by Trout Liver S9 Fractions: Evaluation of Competitive Inhibition Using a Substrate Depletion Approach. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:2729-2739. [PMID: 31505707 PMCID: PMC6952120 DOI: 10.1002/etc.4595] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/24/2019] [Accepted: 09/04/2019] [Indexed: 05/25/2023]
Abstract
Environmental contaminants frequently occur as part of a chemical mixture, potentially resulting in competitive inhibition among multiple substrates metabolized by the same enzyme. Trout liver S9 fractions were used to evaluate the biotransformation of 3 polycyclic aromatic hydrocarbons (PAHs): phenanthrene, pyrene, and benzo[a]pyrene, tested as binary mixtures. Initial rates of biotransformation were determined using a substrate-depletion approach. The resulting data were then fitted by simultaneous nonlinear regression to a competitive inhibition model. In each case, the PAH possessing the lower Michaelis-Menten affinity constant (KM ) competitively inhibited biotransformation of the other compound. Inhibition constants determined for the lower-KM compound were generally close to previously determined KM values, consistent with the suggestion that phase I biotransformation of PAHs is largely catalyzed by one or a small number of cytochrome P450 enzymes. The use of a substrate-depletion approach to perform enzyme-inhibition studies imposes practical limitations on experimental design and complicates the interpretation of derived kinetic constants. Nevertheless, the resulting information may have utility for chemical hazard assessments as well as the design and interpretation of controlled laboratory studies. Depletion experiments informed by measured chemical concentrations in tissues may also provide a means of determining whether enzyme inhibition occurs under relevant environmental conditions. Environ Toxicol Chem 2019;38:2729-2739. Published 2019 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work, and as such, is in the public domain in the United States of America.
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16
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Lammel T, Tsoukatou G, Jellinek J, Sturve J. Development of three-dimensional (3D) spheroid cultures of the continuous rainbow trout liver cell line RTL-W1. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 167:250-258. [PMID: 30342358 DOI: 10.1016/j.ecoenv.2018.10.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 09/29/2018] [Accepted: 10/02/2018] [Indexed: 06/08/2023]
Abstract
In vitro experimental systems based on continuous piscine cell lines can be used as an alternative to animal tests for obtaining qualitative and quantitative information on the possible fate and effect of chemicals in fish. However, their capability to reproduce complex metabolic processes and toxic responses as they occur in vivo is limited due to the lack of organ-specific tissue architecture and functions. Here we introduce a three-dimensional (3D) in vitro experimental system based on spheroidal aggregate cultures (spheroids) of the continuous rainbow trout liver cell line RTL-W1 and provide a first description of their structural and functional properties including growth, viability/longevity, metabolic activity, ultrastructure and cytochrome P450 1A (CYP1A) expression determined by bright-field, multi-photon fluorescence and transmission electron microscopy as well as RT-qPCR analysis. Our results show that RTL-W1 cells in 3D spheroids (ø ~ 150 µm) (including those in the interior) were viable, metabolically active and had higher basal and β-naphthoflavone-induced CYP1A expression levels than conventional 2D cell cultures. Furthermore, they displayed ultrastructural characteristics similar to differentiated hepatocytes. The available evidence suggests that 3D RTL-W1 spheroids may have enhanced hepatotypic functions and be a superior in vitro model to assess hepatic biotransformation, bioaccumulation and chronic toxicity compared to conventional cell monolayer cultures.
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Affiliation(s)
- Tobias Lammel
- Department of Biological and Environmental Sciences, University of Gothenburg, Medicinaregatan 18 A, Box 463, 413 90 Göteborg, Sweden.
| | - Georgia Tsoukatou
- Department of Biological and Environmental Sciences, University of Gothenburg, Medicinaregatan 18 A, Box 463, 413 90 Göteborg, Sweden
| | - Johanna Jellinek
- Department of Biological and Environmental Sciences, University of Gothenburg, Medicinaregatan 18 A, Box 463, 413 90 Göteborg, Sweden
| | - Joachim Sturve
- Department of Biological and Environmental Sciences, University of Gothenburg, Medicinaregatan 18 A, Box 463, 413 90 Göteborg, Sweden
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17
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Nichols JW, Ladd MA, Fitzsimmons PN. Measurement of kinetic parameters for biotransformation of polycyclic aromatic hydrocarbons by trout liver S9 fractions: Implications for bioaccumulation assessment. ACTA ACUST UNITED AC 2018; 4:365-378. [PMID: 31179352 DOI: 10.1089/aivt.2017.0005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In vitro substrate depletion methods developed by the pharmaceutical industry are being used with increasing frequency to support chemical bioaccumulation assessments for fish. However, the application of these methods to high log K ow chemicals poses special challenges. Biotransformation of three polycyclic aromatic hydrocarbons (PAHs) was measured using trout liver S9 fractions. Measured activity declined with incubation time and was reduced by acetone (used as a spiking solvent) at concentrations greater than 0.5%. Addition of alamethicin, a pore-forming peptide used to support UDP-glucuronosyltransferase activity, also reduced activity in a concentration-dependent manner. The substrate concentration dependence of activity was evaluated to estimate K M and V max values for each compound. Derived kinetic constants suggested that all three PAHs are transformed by the same reaction pathway and indicated an inverse correlation between K M and chemical log K ow. Binding effects on activity were evaluated by measuring unbound chemical concentrations across a range of S9 protein levels. Reaction rates were proportional to the unbound concentration except when these concentrations approached saturating levels, providing a direct demonstration of the free chemical hypothesis. These findings suggest that previous in vitro work with high log K ow compounds was conducted at inappropriately high substrate concentrations resulting in underestimation of true in vivo activity. Preliminary calculations also indicate that PAH metabolism in fish may approach saturation during standardized in vivo testing efforts, potentially resulting in concentration-dependent accumulation and/or steady-state levels of accumulation greater than those which occur in a natural setting.
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Affiliation(s)
- John W Nichols
- US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA
| | - Melanie A Ladd
- US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA
| | - Patrick N Fitzsimmons
- US Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN, USA
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18
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Fitzsimmons PN, Hoffman AD, Fay KA, Nichols JW. Allometric scaling of hepatic biotransformation in rainbow trout. Comp Biochem Physiol C Toxicol Pharmacol 2018; 214:52-60. [PMID: 30172734 PMCID: PMC6349251 DOI: 10.1016/j.cbpc.2018.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/20/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022]
Abstract
Biotransformation may substantially impact the toxicity and accumulation of xenobiotic chemicals in fish. However, this activity can vary substantially within and among species. In this study, liver S9 fractions from rainbow trout (4-400 g) were used to evaluate relationships between fish body mass and the activities of phase I and phase II metabolic enzymes. An analysis of log-transformed data, expressed per gram of liver (g liver-1), showed that total cytochrome P450 (CYP) concentration, UDP-glucuronosyltransferase (UGT) activity, and glutathione S-transferase (GST) activity exhibited small but significant inverse relationships with fish body weight. In contrast, in vitro intrinsic clearance rates (CLIN VITRO,INT) for three polycyclic aromatic hydrocarbons (PAHs) increased with increasing body weight. Weight normalized liver mass also decreased inversely with body weight, suggesting a need to express hepatic metabolism data per gram of body weight (g BW-1) in order to reflect the metabolic capabilities of the whole animal. When the data were recalculated in this manner, negative allometric relationships for CYP concentration, UGT activity, and GST activity became more pronounced, while CLIN VITRO,INT rates for the three PAHs showed no significant differences across fish sizes. Ethoxyresorufin O-deethylase (EROD) activity normalized to tissue weight (g liver-1) or body weight (g BW-1) exhibited a non-monotonic pattern with respect to body weight. The results of this study may have important implications for chemical modeling efforts with fish.
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Affiliation(s)
- Patrick N Fitzsimmons
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Boulevard, Duluth, MN 55804, United States of America.
| | - Alex D Hoffman
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Boulevard, Duluth, MN 55804, United States of America
| | - Kellie A Fay
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Boulevard, Duluth, MN 55804, United States of America
| | - John W Nichols
- U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, 6201 Congdon Boulevard, Duluth, MN 55804, United States of America
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19
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Nichols J, Fay K, Bernhard MJ, Bischof I, Davis J, Halder M, Hu J, Johanning K, Laue H, Nabb D, Schlechtriem C, Segner H, Swintek J, Weeks J, Embry M. Reliability of In Vitro Methods Used to Measure Intrinsic Clearance of Hydrophobic Organic Chemicals by Rainbow Trout: Results of an International Ring Trial. Toxicol Sci 2018; 164:563-575. [PMID: 29767801 PMCID: PMC6061802 DOI: 10.1093/toxsci/kfy113] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In vitro assays are widely employed to obtain intrinsic clearance estimates used in toxicokinetic modeling efforts. However, the reliability of these methods is seldom reported. Here we describe the results of an international ring trial designed to evaluate two in vitro assays used to measure intrinsic clearance in rainbow trout. An important application of these assays is to predict the effect of biotransformation on chemical bioaccumulation. Six laboratories performed substrate depletion experiments with cyclohexyl salicylate, fenthion, 4-n-nonylphenol, deltamethrin, methoxychlor, and pyrene using cryopreserved hepatocytes and liver S9 fractions from trout. Variability within and among laboratories was characterized as the percent coefficient of variation (CV) in measured in vitro intrinsic clearance rates (CLIN VITRO, INT; ml/h/mg protein or 106 cells) for each chemical and test system. Mean intralaboratory CVs for each test chemical averaged 18.9% for hepatocytes and 14.1% for S9 fractions, whereas interlaboratory CVs (all chemicals and all tests) averaged 30.1% for hepatocytes and 22.4% for S9 fractions. When CLIN VITRO, INT values were extrapolated to in vivo intrinsic clearance estimates (CLIN VIVO, INT; l/d/kg fish), both assays yielded similar levels of activity (<4-fold difference for all chemicals). Hepatic clearance rates (CLH; l/d/kg fish) calculated using data from both assays exhibited even better agreement. These findings show that both assays are highly reliable and suggest that either may be used to inform chemical bioaccumulation assessments for fish. This study highlights several issues related to the demonstration of assay reliability and may provide a template for evaluating other in vitro biotransformation assays.
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Affiliation(s)
- John Nichols
- ORD, NHEERL, Mid-Continent Ecology Division, U.S. Environmental Protection Agency, Duluth, Minnesota
| | - Kellie Fay
- Biology Department, University of Minnesota, Duluth, Minnesota, 55804
- CSRA Inc, Duluth, Minnesota
| | | | - Ina Bischof
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany, 57392
| | - John Davis
- The Dow Chemical Company, Midland, Michigan, 48674
| | - Marlies Halder
- European Commission, Joint Research Centre, Ispra, Italy, I-21027
| | - Jing Hu
- The Dow Chemical Company, Midland, Michigan, 48674
| | | | - Heike Laue
- Givaudan Schweiz AG, Dübendorf, Switzerland, 8600
| | - Diane Nabb
- DuPont Haskell Global Centers for Health and Environmental Sciences, Newark, Delaware
| | - Christian Schlechtriem
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany, 57392
| | - Helmut Segner
- Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland, 3001
| | - Joe Swintek
- Badger Technical Services, Duluth, Minnesota, 55804
| | - John Weeks
- Weeks Entox, Knoxville, Tennessee, 37931
| | - Michelle Embry
- Health and Environmental Sciences Institute, Washington, District of Columbia 20005
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20
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Rehberger K, Kropf C, Segner H. In vitro or not in vitro: a short journey through a long history. ENVIRONMENTAL SCIENCES EUROPE 2018; 30:23. [PMID: 30009109 PMCID: PMC6018605 DOI: 10.1186/s12302-018-0151-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 06/06/2018] [Indexed: 05/19/2023]
Abstract
The aim of ecotoxicology is to study toxic effects on constituents of ecosystems, with the protection goal being populations and communities rather than individual organisms. In this ecosystem perspective, the use of in vitro methodologies measuring cellular and subcellular endpoints at a first glance appears to be odd. Nevertheless, more recently in vitro approaches gained momentum in ecotoxicology. In this article, we will discuss important application domains of in vitro methods in ecotoxicology. One area is the use of in vitro assays to replace, reduce, and refine (3R) in vivo tests. Research in this field has focused mainly on the use of in vitro cytotoxicity assays with fish cells as non-animal alternative to the in vivo lethality test with fish and on in vitro biotransformation assays as part of an alternative testing strategy for bioaccumulation testing with fish. Lessons learned from this research include the importance of a critical evaluation of the sensitivity, specificity and exposure conditions of in vitro assays, as well as the availability of appropriate in vitro-in vivo extrapolation models. In addition to this classical 3R application, other application domains of in vitro assays in ecotoxicology include the screening and prioritization of chemical hazards, the categorization of chemicals according to their modes of action and the provision of mechanistic information for the pathway-based prediction of adverse outcomes. The applications discussed in this essay may highlight the potential of in vitro technologies to enhance the environmental hazard assessment of single chemicals and complex mixtures at a reduced need of animal testing.
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Affiliation(s)
- Kristina Rehberger
- Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, P O Box, 3001 Bern, Switzerland
| | - Christian Kropf
- Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, P O Box, 3001 Bern, Switzerland
| | - Helmut Segner
- Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, P O Box, 3001 Bern, Switzerland
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21
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Frew JA, Brown JT, Fitzsimmons PN, Hoffman AD, Sadilek M, Grue CE, Nichols JW. Toxicokinetics of the neonicotinoid insecticide imidacloprid in rainbow trout (Oncorhynchus mykiss). Comp Biochem Physiol C Toxicol Pharmacol 2018; 205:34-42. [PMID: 29378254 PMCID: PMC5847319 DOI: 10.1016/j.cbpc.2018.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/17/2018] [Accepted: 01/21/2018] [Indexed: 11/28/2022]
Abstract
Studies were conducted to determine the distribution and elimination of imidacloprid (IMI) in rainbow trout. Animals were injected with a low (47.6 μg/kg), medium (117.5 μg/kg) or high (232.7 μg/kg) dose directly into the bloodstream and allowed to depurate. The fish were then sampled to characterize the loss of IMI from plasma and its appearance in expired water (all dose groups) and urine (medium dose only). In vitro biotransformation of IMI was evaluated using trout liver S9 fractions. Mean total clearance (CLT) values determined by non-compartmental analysis of plasma time-course data were 21.8, 27.0 and 19.5 mL/h/kg for the low, medium and high dose groups, respectively. Estimated half-lives for the same groups were 67.0, 68.4 and 68.1 h, while fitted values for the steady-state volume of distribution (VSS) were 1.72, 2.23 and 1.81 L/kg. Branchial elimination rates were much lower than expected, suggesting that IMI is highly bound in blood. Renal clearance rates were greater than measured rates of branchial clearance (60% of CLT in the medium dose group), possibly indicating a role for renal membrane transporters. There was no evidence for hepatic biotransformation of IMI. Collectively, these findings suggest that IMI would accumulate in trout in continuous waterborne exposures.
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Affiliation(s)
- John A Frew
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St, Box 355020, Seattle, WA 19195-5020, United States.
| | - Jacob T Brown
- College of Pharmacy, University of Minnesota, Life Science 232, 1110 Kirby Drive, Duluth, MN 55812-3003, United States
| | - Patrick N Fitzsimmons
- Mid-Continent Ecology Division, U.S. Environmental Protection Agency, 6201 Congdon Blvd, Duluth, MN 55804, United States
| | - Alex D Hoffman
- Mid-Continent Ecology Division, U.S. Environmental Protection Agency, 6201 Congdon Blvd, Duluth, MN 55804, United States
| | - Martin Sadilek
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, United States
| | - Christian E Grue
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St, Box 355020, Seattle, WA 19195-5020, United States
| | - John W Nichols
- Mid-Continent Ecology Division, U.S. Environmental Protection Agency, 6201 Congdon Blvd, Duluth, MN 55804, United States
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22
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Bussy U, Chung-Davidson YW, Buchinger T, Li K, Smith SA, Jones AD, Li W. Metabolism of a sea lamprey pesticide by fish liver enzymes part A: identification and synthesis of TFM metabolites. Anal Bioanal Chem 2017; 410:1749-1761. [DOI: 10.1007/s00216-017-0830-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/27/2017] [Accepted: 12/13/2017] [Indexed: 11/30/2022]
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23
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Chen Y, Hermens JLM, Jonker MTO, Arnot JA, Armitage JM, Brown T, Nichols JW, Fay KA, Droge STJ. Which Molecular Features Affect the Intrinsic Hepatic Clearance Rate of Ionizable Organic Chemicals in Fish? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:12722-12731. [PMID: 27934284 DOI: 10.1021/acs.est.6b03504] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Greater knowledge of biotransformation rates for ionizable organic compounds (IOCs) in fish is required to properly assess the bioaccumulation potential of many environmentally relevant contaminants. In this study, we measured in vitro hepatic clearance rates for 50 IOCs using a pooled batch of liver S9 fractions isolated from rainbow trout (Oncorhynchus mykiss). The IOCs included four types of strongly ionized acids (carboxylates, phenolates, sulfonates, and sulfates), three types of strongly ionized bases (primary, secondary, tertiary amines), and a pair of quaternary ammonium compounds (QACs). Included in this test set were several surfactants and a series of beta-blockers. For linear alkyl chain IOC analogues, biotransformation enzymes appeared to act directly on the charged terminal group, with the highest clearance rates for tertiary amines and sulfates and no clearance of QACs. Clearance rates for C12-IOCs were higher than those for C8-IOC analogues. Several analogue series with multiple alkyl chains, branched alkyl chains, aromatic rings, and nonaromatic rings were evaluated. The likelihood of multiple reaction pathways made it difficult to relate all differences in clearance to specific molecular features the tested IOCs. Future analysis of primary metabolites in the S9 assay is recommended to further elucidate biotransformation pathways for IOCs in fish.
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Affiliation(s)
- Yi Chen
- Institute for Risk Assessment Sciences, Utrecht University , Utrecht, 3508 TD, The Netherlands
| | - Joop L M Hermens
- Institute for Risk Assessment Sciences, Utrecht University , Utrecht, 3508 TD, The Netherlands
| | - Michiel T O Jonker
- Institute for Risk Assessment Sciences, Utrecht University , Utrecht, 3508 TD, The Netherlands
| | - Jon A Arnot
- Department of Physical and Environmental Sciences, University of Toronto Scarborough , Toronto, Ontario M1C 1A4, Canada
- ARC Arnot Research and Consulting , Toronto, Ontario M4M 1W4, Canada
| | - James M Armitage
- Department of Physical and Environmental Sciences, University of Toronto Scarborough , Toronto, Ontario M1C 1A4, Canada
- ARC Arnot Research and Consulting , Toronto, Ontario M4M 1W4, Canada
| | - Trevor Brown
- ARC Arnot Research and Consulting , Toronto, Ontario M4M 1W4, Canada
| | - John W Nichols
- US Environmental Protection Agency , Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, Minnesota 55804, United States
| | - Kellie A Fay
- US Environmental Protection Agency , Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, Minnesota 55804, United States
| | - Steven T J Droge
- Institute for Risk Assessment Sciences, Utrecht University , Utrecht, 3508 TD, The Netherlands
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Ladd MA, Fitzsimmons PN, Nichols JW. Optimization of a UDP-glucuronosyltransferase assay for trout liver S9 fractions: activity enhancement by alamethicin, a pore-forming peptide. Xenobiotica 2016; 46:1066-1075. [DOI: 10.3109/00498254.2016.1149634] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Melanie A. Ladd
- United States Environmental Protection Agency (US EPA), ORD, NHEERL, Mid-Continent Ecology Division, Duluth, MN, USA
| | - Patrick N. Fitzsimmons
- United States Environmental Protection Agency (US EPA), ORD, NHEERL, Mid-Continent Ecology Division, Duluth, MN, USA
| | - John W. Nichols
- United States Environmental Protection Agency (US EPA), ORD, NHEERL, Mid-Continent Ecology Division, Duluth, MN, USA
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25
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Hoke R, Huggett D, Brasfield S, Brown B, Embry M, Fairbrother A, Kivi M, Paumen ML, Prosser R, Salvito D, Scroggins R. Review of laboratory-based terrestrial bioaccumulation assessment approaches for organic chemicals: Current status and future possibilities. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2016; 12:109-122. [PMID: 26272585 DOI: 10.1002/ieam.1692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/09/2015] [Accepted: 07/13/2015] [Indexed: 06/04/2023]
Abstract
In the last decade, interest has been renewed in approaches for the assessment of the bioaccumulation potential of chemicals, principally driven by the need to evaluate large numbers of chemicals as part of new chemical legislation, while reducing vertebrate test organism use called for in animal welfare legislation. This renewed interest has inspired research activities and advances in bioaccumulation science for neutral organic chemicals in aquatic environments. In January 2013, ILSI Health and Environmental Sciences Institute convened experts to identify the state of the science and existing shortcomings in terrestrial bioaccumulation assessment of neutral organic chemicals. Potential modifications to existing laboratory methods were identified, including areas in which new laboratory approaches or test methods could be developed to address terrestrial bioaccumulation. The utility of "non-ecotoxicity" data (e.g., mammalian laboratory data) was also discussed. The highlights of the workshop discussions are presented along with potential modifications in laboratory approaches and new test guidelines that could be used for assessing the bioaccumulation of chemicals in terrestrial organisms.
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Affiliation(s)
- Robert Hoke
- DuPont, Haskell Global Centers for Health and Environmental Sciences, Newark, Delaware, USA
| | | | - Sandra Brasfield
- US Army Engineer Research and Development Center, Vicksburg, Mississippi
| | - Becky Brown
- AstraZeneca, Global Environment, Cheshire, United Kingdom; Present address: WCA, Brunel House, Volunteer Way, Faringdon, Oxfordshire, United Kingdom
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Fay KA, Nabb DL, Mingoia RT, Bischof I, Nichols JW, Segner H, Johanning K, Han X. Determination of Metabolic Stability Using Cryopreserved Hepatocytes from Rainbow Trout (
Oncorhynchus mykiss
). ACTA ACUST UNITED AC 2015; 65:4.42.1-4.42.29. [DOI: 10.1002/0471140856.tx0442s65] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kellie A. Fay
- ORD/NHEERL/Mid‐Continent Ecology Division, U.S. EPA Duluth Minnesota
| | - Diane L. Nabb
- DuPont Haskell Global Centers for Health and Environmental Sciences Newark Delaware
| | - Robert T. Mingoia
- DuPont Haskell Global Centers for Health and Environmental Sciences Newark Delaware
| | - Ina Bischof
- Centre for Fish and Wildlife Health, University of Bern Bern Switzerland
- Fraunhofer Institute for Molecular Biology and Applied Ecology Schmallenberg Germany
| | - John W. Nichols
- ORD/NHEERL/Mid‐Continent Ecology Division, U.S. EPA Duluth Minnesota
| | - Helmut Segner
- Centre for Fish and Wildlife Health, University of Bern Bern Switzerland
| | - Karla Johanning
- KJ Scientific LCC, Texas Life Sciences Collaboration Center Georgetown Texas
| | - Xing Han
- DuPont Haskell Global Centers for Health and Environmental Sciences Newark Delaware
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27
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Segner H. In vitro methodologies in ecotoxicological hazard assessment: the case of bioaccumulation testing for fish. Altern Lab Anim 2015; 43:P14-6. [PMID: 25995015 DOI: 10.1177/026119291504300209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The concerted research efforts undertaken in recent years have highlighted the potential of in vitro approaches, as part of an integrated testing strategy, to replace or reduce in vivo bioaccumulation testing in fish
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Affiliation(s)
- Helmut Segner
- Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, PO Box 8466, CH 3012 Bern, Switzerland
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28
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Treu G, Drost W, Jöhncke U, Rauert C, Schlechtriem C. The Dessau workshop on bioaccumulation: state of the art, challenges and regulatory implications. ENVIRONMENTAL SCIENCES EUROPE 2015; 27:34. [PMID: 27752435 PMCID: PMC5044950 DOI: 10.1186/s12302-015-0067-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 12/07/2015] [Indexed: 05/10/2023]
Abstract
Bioaccumulation plays a vital role in understanding the fate of a substance in the environment and is key to the regulation of chemicals in several jurisdictions. The current assessment approaches commonly use the octanol-water partition coefficient (log KOW) as an indicator for bioaccumulation and the bioconcentration factor (BCF) as a standard criterion to identify bioaccumulative substances show limitations. The log KOW does not take into account active transport phenomena or special structural properties (e.g., amphiphilic substances or dissociating substances) and therefore additional screening criteria are required. Regulatory BCF studies are so far restricted to fish and uptake through the gills. Studies on (terrestrial) air-breathing organisms are missing. Though there are alternative tests such as the dietary exposure bioaccumulation fish test described in the recently revised OECD test guideline 305, it still remains unclear how to deal with results of alternative tests in regulatory decision-making processes. A substantial number of bioaccumulation fish tests are required in regulation. The development of improved test systems following the 3R principles, namely to replace, reduce and refine animal testing, is thus required. All these aspects stress the importance to further develop the assessment of bioaccumulation. The Dessau Workshop on Bioaccumulation which was held from June 26th to 27th 2014, in Dessau, Germany, provided a comprehensive overview of the state of the art of bioaccumulation assessment, provided insights into the problems and challenges addressed by the regulatory authorities and described new research concepts and their regulatory implications. The event was organised by UBA (Dessau, Germany) and Fraunhofer IME (Schmallenberg, Germany). About 50 participants from industry, regulatory bodies and academia listened to 14 lectures on selected topics and joined the plenary discussions.
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Affiliation(s)
- Gabriele Treu
- Umweltbundesamt (UBA), PO Box 1406, 06844 Dessau-Rosslau, Germany
| | - Wiebke Drost
- Umweltbundesamt (UBA), PO Box 1406, 06844 Dessau-Rosslau, Germany
| | - Ulrich Jöhncke
- Umweltbundesamt (UBA), PO Box 1406, 06844 Dessau-Rosslau, Germany
| | - Caren Rauert
- Umweltbundesamt (UBA), PO Box 1406, 06844 Dessau-Rosslau, Germany
| | - Christian Schlechtriem
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), PO Box 12 60, 57377 Schmallenberg, Germany
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Abdallah MAE, Uchea C, Chipman JK, Harrad S. Enantioselective biotransformation of hexabromocyclododecane by in vitro rat and trout hepatic sub-cellular fractions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:2732-2740. [PMID: 24483621 DOI: 10.1021/es404644s] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
α-, β-, and γ-Hexabromocyclododecanes (HBCDs) were subjected to in vitro biotransformation experiments with rat and trout liver S9 fractions for different incubation times (10, 30, and 60 min) at 2 concentration levels (1 and 10 μM). The metabolic degradation of target HBCDs followed first order kinetics. Whereas β-HBCD undergoes rapid biotransformation (t0.5 = 6.4 and 38.1 min in rat and trout, respectively), α-HBCD appears the most resistant to metabolic degradation (t0.5 = 17.1 and 134.9 min). The biotransformation rate in trout was slower than in rat. Investigation of HBCD degradation profiles revealed the presence of at least 3 pentabromocyclododecene (PBCD) and 2 tetrabromocyclododecadiene (TBCD) isomers indicating reductive debromination as a metabolic pathway for HBCDs. Both mono- and di- hydroxyl metabolites were identified for parent HBCDs, while only mono hydroxyl metabolites were detected for PBCDs and TBCDs. Interestingly, δ-HBCD was detected only in trout S9 fraction assays indicating metabolic interconversion of test HBCD diastereomers during biotransformation in trout. Finally, enantioselective analysis showed significant enrichment of the (-)-α-HBCD enantiomer (EF = 0.321 and 0.419 after 60 min incubation in rat and trout, respectively). The greater enrichment of (-)-α-HBCD in rat than in trout underlines the species-specific differences in HBCD metabolism and the need for caution when extending similar results from animal studies to humans.
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Affiliation(s)
- Mohamed Abou-Elwafa Abdallah
- Division of Environmental Health and Risk Management, School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham, B15 2TT, United Kingdom
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