1
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Gimeno S, Allan D, Paul K, Remuzat P, Collard M. Are current regulatory log K ow cut-off values fit-for-purpose as a screening tool for bioaccumulation potential in aquatic organisms? Regul Toxicol Pharmacol 2024; 147:105556. [PMID: 38158033 DOI: 10.1016/j.yrtph.2023.105556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 12/07/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024]
Abstract
Persistent, Bioaccumulative and Toxic (PBT) and very Persistent and very Bioaccumulative (vPvB) are regulatory hazard categories that have been set to manage the possible risks to humans and the environment from these chemicals. In industrial chemicals regulations, their aquatic Bioaccumulation potential is usually assessed first with a screening based on the octanol/water partition coefficient (Kow). However, current log Kow cut-off values triggering classification, categorisation and/or further fish bioconcentration testing are not harmonised worldwide, and they have never been assessed for their regulatory relevance. In this study, the experimentally determined log Kow and fish bioconcentration factors (BCF) of 532 chemicals were compared. While the analysis underlined the robustness of using log Kow as a screening tool (5/532 were false negatives; log Kow: non-bioaccumulative, but BCF: bioaccumulative), it also demonstrated the conservatism of the cut-offs used worldwide. Indeed, many chemicals were deemed potentially Bioaccumulative based on log Kow when a fish bioaccumulation test showed no concern (false positives), therefore, leading to unnecessary use of vertebrate animals. Our analysis shows that the log Kow cut-off could be increased to 4.5 in all regions for all purposes without leading to a reduced protection of humans and the environment.
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Affiliation(s)
| | - Dawn Allan
- Anthesis (UK) Limited, London, United Kingdom.
| | - Kai Paul
- Blue Frog Scientific Limited, Edinburgh, United Kingdom.
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2
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Belanger SE, Lillicrap AD, Moe SJ, Wolf R, Connors K, Embry MR. Weight of evidence tools in the prediction of acute fish toxicity. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2023; 19:1220-1234. [PMID: 35049115 DOI: 10.1002/ieam.4581] [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: 09/21/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Acute fish toxicity (AFT) is a key endpoint in nearly all regulatory implementations of environmental hazard assessments of chemicals globally. Although it is an early tier assay, the AFT assay is complex and uses many juvenile fish each year for the registration and assessment of chemicals. Thus, it is imperative to seek animal alternative approaches to replace or reduce animal use for environmental hazard assessments. A Bayesian Network (BN) model has been developed that brings together a suite of lines of evidence (LoEs) to produce a probabilistic estimate of AFT without the testing of additional juvenile fish. Lines of evidence include chemical descriptors, mode of action (MoA) assignment, knowledge of algal and daphnid acute toxicity, and animal alternative assays such as fish embryo tests and in vitro fish assays (e.g., gill cytotoxicity). The effort also includes retrieval, assessment, and curation of quality acute fish toxicity data because these act as the baseline of comparison with model outputs. An ideal outcome of this effort would be to have global applicability, acceptance and uptake, relevance to predominant fish species used in chemical assessments, be expandable to allow incorporation of future knowledge, and data to be publicly available. The BN model can be conceived as having incorporated principles of tiered assessment and whose outcomes will be directed by the available evidence in combination with prior information. We demonstrate that, as additional evidence is included in the prediction of a given chemical's ecotoxicity profile, both the accuracy and the precision of the predicted AFT can increase. Ultimately an improved environmental hazard assessment will be achieved. Integr Environ Assess Manag 2023;19:1220-1234. © 2022 SETAC.
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Affiliation(s)
| | | | - S Jannicke Moe
- Norwegian Institute for Water Research (NIVA), Oslo, Norway
| | - Raoul Wolf
- Norwegian Institute for Water Research (NIVA), Oslo, Norway
- Norwegian Geotechnical Institute (NGI), Oslo, Norway
| | | | - Michelle R Embry
- Health and Environmental Sciences Institute, Washington, DC, USA
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3
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Coors A, Brown AR, Maynard SK, Nimrod Perkins A, Owen S, Tyler CR. Minimizing Experimental Testing on Fish for Legacy Pharmaceuticals. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:1721-1730. [PMID: 36653019 PMCID: PMC9893720 DOI: 10.1021/acs.est.2c07222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/09/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
There was no regulatory requirement for ecotoxicological testing of human pharmaceuticals authorized before 2006, and many of these have little or no data available to assess their environmental risk. Motivated by animal welfare considerations, we developed a decision tree to minimize in vivo fish testing for such legacy active pharmaceutical ingredients (APIs). The minimum no observed effect concentration (NOECmin, the lowest NOEC from chronic Daphnia and algal toxicity studies), the theoretical therapeutic water concentration (TWC, calculated using the fish plasma model), and the predicted environmental concentration (PEC) were used to derive API risk quotients (PEC/NOECmin and PEC/TWC). Based on a verification data set of 96 APIs, we show that by setting a threshold value of 0.001 for both risk quotients, the need for in vivo fish testing could potentially be reduced by around 35% without lowering the level of environmental protection. Hence, for most APIs, applying an assessment factor of 1000 (equivalent to the threshold of 0.001) to NOECmin substituted reliably for NOECfish, and TWC acted as an effective safety net for the others. In silico and in vitro data and mammalian toxicity data may further support the final decision on the need for fish testing.
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Affiliation(s)
- Anja Coors
- ECT
Oekotoxikologie GmbH, Böttgerstraße 2-14, 65439 Flörsheim/Main, Germany
| | - A. Ross Brown
- Biosciences, University of Exeter, Geoffrey Pope Building, Stocker
Road, Exeter EX4 4QD, Devon, U.K.
| | - Samuel K. Maynard
- Global
Sustainability, AstraZeneca, Eastbrook House, Shaftesbury Road, Cambridge CB2 8DU, U.K.
| | - Alison Nimrod Perkins
- Eli
Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, United States
| | - Stewart Owen
- Global
Sustainability, AstraZeneca, Eastbrook House, Shaftesbury Road, Cambridge CB2 8DU, U.K.
| | - Charles R. Tyler
- Biosciences, University of Exeter, Geoffrey Pope Building, Stocker
Road, Exeter EX4 4QD, Devon, U.K.
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4
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Schultz M, Krause S, Brinkmann M. Validation of Methods for in Vitro- in Vivo Extrapolation Using Hepatic Clearance Measurements in Isolated Perfused Fish Livers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12416-12423. [PMID: 35994365 DOI: 10.1021/acs.est.2c02656] [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: 06/15/2023]
Abstract
In vitro biotransformation assays using hepatocytes or liver subcellular fractions, combined with in vitro-in vivo extrapolation (IVIVE) models, have been proposed as an alternative to live fish bioconcentration studies. The uncertainty associated with IVIVE approaches to date has been attributed to assay protocols, model assumptions, or variability of in vivo data. An isolated perfused trout liver model that measures hepatic clearance has been proposed for validating IVIVE predictions in the absence of other confounding factors. Here, we investigated the hepatic clearances of five chemicals (pyrene, phenanthrene, 4-n-nonlyphenol, deltamethrin, and methoxychlor) in this model and compared measured rates to values predicted from published in vitro intrinsic clearances for validation of IVIVE models. Additionally, we varied protein concentrations in perfusates to test binding assumptions of these models. We found that measured and predicted hepatic clearances were in very good agreement (root mean squared error 16.8 mL h-1 g-1) across three levels of protein binding and across a more diverse chemical space than previously studied within this system. Our results show that current IVIVE methods can reliably predict in vivo clearance rates and indicate that discrepancies from measured bioconcentration factors might be driven by other processes, such as extrahepatic biotransformation, etc., and help streamline optimization efforts to the processes that truly matter.
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Affiliation(s)
- Matthew Schultz
- Toxicology Center, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada
| | - Sophia Krause
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research UFZ, Permoserstr. 15, 04318 Leipzig, Germany
| | - Markus Brinkmann
- Toxicology Center, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada
- School of Environment and Sustainability, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8, Canada
- Global Institute for Water Security, University of Saskatchewan, 11 Innovation Boulevard, Saskatoon, SK S7N 3H5, Canada
- Centre for Hydrology, University of Saskatchewan, 121 Research Drive, Saskatoon, SK S7N 1K2, Canada
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5
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Maculewicz J, Świacka K, Kowalska D, Stepnowski P, Stolte S, Dołżonek J. In vitro methods for predicting the bioconcentration of xenobiotics in aquatic organisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 739:140261. [PMID: 32758962 DOI: 10.1016/j.scitotenv.2020.140261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/10/2020] [Accepted: 06/14/2020] [Indexed: 06/11/2023]
Abstract
The accumulation of anthropogenic chemical substances in aquatic organisms is an immensely important issue from the point of view of environmental protection. In the context of the increasing number and variety of compounds that may potentially enter the environment, there is a need for efficient and reliable solutions to assess the risks. However, the classic approach of testing with fish or other animals is not sufficient. Due to very high costs, significant time and labour intensity, as well as ethical concerns, in vivo methods need to be replaced by new laboratory-based tools. So far, many models have been developed to estimate the bioconcentration potential of chemicals. However, most of them are not sufficiently reliable and their predictions are based on limited input data, often obtained with doubtful quality. The octanol-water partition coefficient is still often used as the main laboratory tool for estimating bioconcentration. However, according to current knowledge, this method can lead to very unreliable results, both for neutral species and, above all, for ionic compounds. It is therefore essential to start using new, more advanced and credible solutions on a large scale. Over the last years, many in vitro methods have been newly developed or improved, allowing for a much more adequate estimation of the bioconcentration potential. Therefore, the aim of this work was to review the most recent laboratory methods for assessing the bioconcentration potential and to evaluate their applicability in further research.
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Affiliation(s)
- Jakub Maculewicz
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
| | - Klaudia Świacka
- Department of Experimental Ecology of Marine Organisms, Institute of Oceanography, University of Gdansk, Av. Pilsudskiego 46, 81-378 Gdynia, Poland
| | - Dorota Kowalska
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Piotr Stepnowski
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Stefan Stolte
- Faculty of Environmental Sciences, Department of Hydrosciences, Institute of Water Chemistry, Technische Universität Dresden, Bergstrasse 66, 01069 Dresden, Germany
| | - Joanna Dołżonek
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
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6
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Lillicrap A, Moe SJ, Wolf R, Connors KA, Rawlings JM, Landis WG, Madsen A, Belanger SE. Evaluation of a Bayesian Network for Strengthening the Weight of Evidence to Predict Acute Fish Toxicity from Fish Embryo Toxicity Data. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2020; 16:452-460. [PMID: 32125082 DOI: 10.1002/ieam.4258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 11/21/2019] [Accepted: 02/20/2020] [Indexed: 06/10/2023]
Abstract
The use of fish embryo toxicity (FET) data for hazard assessments of chemicals, in place of acute fish toxicity (AFT) data, has long been the goal for many environmental scientists. The FET test was first proposed as a replacement to the standardized AFT test nearly 15 y ago, but as of now, it has still not been accepted as a standalone replacement by regulatory authorities such as the European Chemicals Agency (ECHA). However, the ECHA has indicated that FET data can be used in a weight of evidence (WoE) approach, if enough information is available to support the conclusions related to the hazard assessment. To determine how such a WoE approach could be applied in practice has been challenging. To provide a conclusive WoE for FET data, we have developed a Bayesian network (BN) to incorporate multiple lines of evidence to predict AFT. There are 4 different lines of evidence in this BN model: 1) physicochemical properties, 2) AFT data from chemicals in a similar class or category, 3) ecotoxicity data from other trophic levels of organisms (e.g., daphnids and algae), and 4) measured FET data. The BN model was constructed from data obtained from a curated database and conditional probabilities assigned for the outcomes of each line of evidence. To evaluate the model, 20 data-rich chemicals, containing a minimum of 3 AFT and FET test data points, were selected to ensure a suitable comparison could be performed. The results of the AFT predictions indicated that the BN model could accurately predict the toxicity interval for 80% of the chemicals evaluated. For the remaining chemicals (20%), either daphnids or algae were the most sensitive test species, and for those chemicals, the daphnid or algal hazard data would have driven the environmental classification. Integr Environ Assess Manag 2020;16:452-460. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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Affiliation(s)
| | | | - Raoul Wolf
- Norwegian Institute for Water Research (NIVA), Oslo
| | | | | | - Wayne G Landis
- Western Washington University, Bellingham, Washington, USA
| | - Anders Madsen
- Department of Computer Science, Aalborg University, Aalborg, Denmark
- HUGIN EXPERT A/S, Aalborg, Denmark
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7
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Hultman MT, Løken KB, Grung M, Reid MJ, Lillicrap A. Performance of Three-Dimensional Rainbow Trout (Oncorhynchus mykiss) Hepatocyte Spheroids for Evaluating Biotransformation of Pyrene. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:1738-1747. [PMID: 31100187 DOI: 10.1002/etc.4476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/20/2019] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
The aquatic bioconcentration of a chemical is typically determined using conventional fish tests. To foster the approach of alternatives to animal testing, a combination of computational models and in vitro substrate depletion bioassays (e.g., primary hepatocytes) can be used. One recently developed in vitro assay is the three-dimensional (3D) hepatic spheroid model from rainbow trout (Oncorhynchus mykiss). The aim of the present study was to evaluate the metabolic competence of the 3D spheroids from rainbow trout when exposed to pyrene, using 2 different sampling procedures (SP1 and SP2). The results were compared with previously published intrinsic clearance (CL) results from S9 fractions and primary hepatocyte assays. Extraction of pyrene using SP1 suggested that the spheroids had depleted 33% of the pyrene within 4 h of exposure, reducing to 91% after 30 h. However, when applying SP2 a substantial amount (36%) of the pyrene was bound to the exposure vial within 2 h, decreasing after 6 h of exposure. Formation of hydroxypyrene-glucuronide (OH-PYR-Glu) was obtained throughout the study, displaying the metabolic competence of the 3D spheroids. The 2 sampling procedures yielded different CLin vitro , where pyrene depletion using SP2 was very similar to published studies using primary hepatocytes. The 3D spheroids demonstrated reproducibile, log-linear biotransformation of pyrene and displayed formation of OH-PYR-Glu, indicating their metabolic competence for 30 h or more. Environ Toxicol Chem 2019;38:1738-1747. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
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Affiliation(s)
| | | | - Merete Grung
- Norwegian Institute for Water Research, Oslo, Norway
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8
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Brooks SJ, Ruus A, Rundberget JT, Kringstad A, Lillicrap A. Bioaccumulation of selected veterinary medicinal products (VMPs) in the blue mussel (Mytilus edulis). THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 655:1409-1419. [PMID: 30577132 DOI: 10.1016/j.scitotenv.2018.11.212] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 11/14/2018] [Accepted: 11/14/2018] [Indexed: 06/09/2023]
Abstract
Veterinary medicinal products (VMPs) are widely used within the fish farming industry to control sea lice infestations. There is concern that wild and farmed mussels in the vicinity to these fish farms may be exposed and subsequently bioaccumulate these chemicals, which could pose a threat to human health. To understand the fate of these chemicals in the environment, controlled laboratory exposures were performed to establish the uptake and depuration of selected VMPs in the blue mussel (Mytilus edulis). The VMPs included teflubenzuron, emamectin benzoate and deltamethrin. The effects of salinity on the bioaccumulation of teflubenzuron were also investigated to see whether mussels in brackish waters exhibit different bioaccumulation dynamics. Salinity had no significant effect on the uptake or depuration curves for teflubenzuron down to 15‰. The uptake rate constants (k1) for teflubenzuron, emamectin benzoate and deltamethrin in mussels were 192, 4.82 and 2003, with kinetic bioconcentration factors (BCFs) of 1304, 49 and 2516. Depuration rate constants (k2) were also found to differ between the three VMPs at 0.147, 0.048 and 0.796 for teflubenzuron, emamectin benzoate and deltamethrin, with calculated elimination half-lives (t1/2)of 4.7, 14 and 0.87 days. The longer elimination half-lives for teflubenzuron and emamectin benzoate, suggest that these chemicals accumulate in blue mussels and therefore have the potential to bioaccumulate in wild and farmed mussel populations in the environment.
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Affiliation(s)
- S J Brooks
- Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway.
| | - A Ruus
- Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway; University of Oslo, Section for Aquatic Biology and Toxicology, Department of Biosciences, Oslo, Norway
| | - J T Rundberget
- Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway
| | - A Kringstad
- Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway
| | - A Lillicrap
- Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, NO-0349 Oslo, Norway
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9
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Chang E, Hogstrand C, Miller TH, Owen SF, Bury NR. The Use of Molecular Descriptors To Model Pharmaceutical Uptake by a Fish Primary Gill Cell Culture Epithelium. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1576-1584. [PMID: 30589539 PMCID: PMC6503469 DOI: 10.1021/acs.est.8b04394] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Modeling approaches such as quantitative structure-activity relationships (QSARs) use molecular descriptors to predict the bioavailable properties of a compound in biota. However, these models have mainly been derived based on empirical data for lipophilic neutral compounds and may not predict the uptake of ionizable compounds. The majority of pharmaceuticals are ionizable, and freshwaters can have a range of pH values that affect speciation. In this study, we assessed the uptake of 10 pharmaceuticals (acetazolamide, beclomethasone, carbamazepine, diclofenac, gemfibrozil, ibuprofen, ketoprofen, norethindrone, propranolol, and warfarin) with differing modes of action and physicochemical properties (p Ka, log S, log D, log Kow, molecular weight (MW), and polar surface area (PSA)) by an in vitro primary fish gill cell culture system (FIGCS) for 24 h in artificial freshwater. Principal component analysis (PCA) and partial least-squares (PLS) regression was used to determine the molecular descriptors that influence the uptake rates. Ionizable drugs were taken up by FIGCS; a strong positive correlation was observed between log S and the uptake rate, and a negative correlation was observed between p Ka, log D, and MW and the uptake rate. This approach shows that models can be derived on the basis of the physicochemical properties of pharmaceuticals and the use of an in vitro gill system to predict the uptake of other compounds. There is a need for a robust and validated model for gill uptake that could be used in a tiered risk assessment to prioritize compounds for experimental testing.
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Affiliation(s)
- Elisabeth
D. Chang
- King’s
College London, Department of Nutritional
Sciences, Franklin Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom
| | - Christer Hogstrand
- King’s
College London, Department of Nutritional
Sciences, Franklin Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom
- E-mail:
| | - Thomas H. Miller
- King’s
College London, Department of Analytical,
Environmental and Forensic Sciences, Franklin Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom
| | - Stewart F. Owen
- AstraZeneca, Global Safety, Health & Environment, Alderley Park, Macclesfield, Cheshire SK10 4TF, United Kingdom
| | - Nic R. Bury
- King’s
College London, Department of Nutritional
Sciences, Franklin Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom
- University
of Suffolk, School of Science,
Technology and Engineering, James Hehir Building, University Quays, Ipswich, Suffolk IP3 0AQ, United Kingdom
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10
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Langan LM, Owen SF, Trznadel M, Dodd NJF, Jackson SK, Purcell WM, Jha AN. Spheroid Size Does not Impact Metabolism of the β-blocker Propranolol in 3D Intestinal Fish Model. Front Pharmacol 2018; 9:947. [PMID: 30186177 PMCID: PMC6113889 DOI: 10.3389/fphar.2018.00947] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/02/2018] [Indexed: 12/12/2022] Open
Abstract
Compared to two-dimensional (2D) cell culture, cellular aggregates or spheroids (3D) offer a more appropriate alternative in vitro system where individual cell-cell communication and micro-environment more closely represent the in vivo organ; yet we understand little of the physiological conditions at this scale. The relationship between spheroid size and oxygen microenvironment, an important factor influencing the metabolic capacity of cells, was first established using the fish intestine derived RTgutGC cell line. Subsequently, pharmaceutical metabolism (Propranolol), as determined by high performance liquid chromatography, in this intestinal model was examined as a function of spheroid size. Co-efficient of variation between spheroid size was below 12% using the gyratory platform method, with the least variation observed in the highest cell seeding density. The viable, high oxygen micro-environment of the outer rim of the spheroid, as determined by electron paramagnetic resonance (EPR) oximetry, decreased over time, and the hypoxic zone increased as a function of spheroid size. Despite a trend of higher metabolism in smaller spheroids, the formation of micro-environments (quiescent, hypoxic or anoxic) did not significantly affect metabolism or function of an environmentally relevant pharmaceutical in this spheroid model.
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Affiliation(s)
- Laura M Langan
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
| | - Stewart F Owen
- Global Sustainability, AstraZeneca, Macclesfield, United Kingdom
| | - Maciej Trznadel
- College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Nicholas J F Dodd
- School of Biomedical and Healthcare Sciences, University of Plymouth, Plymouth, United Kingdom
| | - Simon K Jackson
- School of Biomedical and Healthcare Sciences, University of Plymouth, Plymouth, United Kingdom
| | - Wendy M Purcell
- Harvard T.H. Chan School of Public Health, Harvard University, Cambridge, MA, United States
| | - Awadhesh N Jha
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, United Kingdom
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11
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Nendza M, Kühne R, Lombardo A, Strempel S, Schüürmann G. PBT assessment under REACH: Screening for low aquatic bioaccumulation with QSAR classifications based on physicochemical properties to replace BCF in vivo testing on fish. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 616-617:97-106. [PMID: 29107783 DOI: 10.1016/j.scitotenv.2017.10.317] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 10/30/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Aquatic bioconcentration factors (BCFs) are critical in PBT (persistent, bioaccumulative, toxic) and risk assessment of chemicals. High costs and use of more than 100 fish per standard BCF study (OECD 305) call for alternative methods to replace as much in vivo testing as possible. The BCF waiving scheme is a screening tool combining QSAR classifications based on physicochemical properties related to the distribution (hydrophobicity, ionisation), persistence (biodegradability, hydrolysis), solubility and volatility (Henry's law constant) of substances in water bodies and aquatic biota to predict substances with low aquatic bioaccumulation (nonB, BCF<2000). The BCF waiving scheme was developed with a dataset of reliable BCFs for 998 compounds and externally validated with another 181 substances. It performs with 100% sensitivity (no false negatives), >50% efficacy (waiving potential), and complies with the OECD principles for valid QSARs. The chemical applicability domain of the BCF waiving scheme is given by the structures of the training set, with some compound classes explicitly excluded like organometallics, poly- and perfluorinated compounds, aromatic triphenylphosphates, surfactants. The prediction confidence of the BCF waiving scheme is based on applicability domain compliance, consensus modelling, and the structural similarity with known nonB and B/vB substances. Compounds classified as nonB by the BCF waiving scheme are candidates for waiving of BCF in vivo testing on fish due to low concern with regard to the B criterion. The BCF waiving scheme supports the 3Rs with a possible reduction of >50% of BCF in vivo testing on fish. If the target chemical is outside the applicability domain of the BCF waiving scheme or not classified as nonB, further assessments with in silico, in vitro or in vivo methods are necessary to either confirm or reject bioaccumulative behaviour.
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Affiliation(s)
- Monika Nendza
- Analytical Laboratory AL-Luhnstedt, Bahnhofstraße 1, 24816 Luhnstedt, Germany.
| | - Ralph Kühne
- UFZ Department of Ecological Chemistry, Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany.
| | - Anna Lombardo
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Environmental Chemistry and Toxicology Laboratory, via La Masa 19, 20156 Milan, Italy.
| | | | - Gerrit Schüürmann
- UFZ Department of Ecological Chemistry, Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany; Institute for Organic Chemistry, Technical University Bergakademie Freiberg, Leipziger Strasse 29, 09596 Freiberg, Germany.
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12
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Langan LM, Arossa S, Owen SF, Jha AN. Assessing the impact of benzo[a]pyrene with the in vitro fish gut model: An integrated approach for eco-genotoxicological studies. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2017; 826:53-64. [PMID: 29412870 DOI: 10.1016/j.mrgentox.2017.12.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/06/2017] [Accepted: 12/18/2017] [Indexed: 12/31/2022]
Abstract
In vitro models are emerging tools for reducing reliance on traditional toxicity tests, especially in areas where information is sparse. For studies of fish, this is especially important for extrahepatic organs, such as the intestine, which, until recently, have been largely overlooked in favour of the liver or gill. Considering the importance of dietary uptake of contaminants, the rainbow trout (Oncorhynchus mykiss) intestine-derived cell line RTgutGC was cultured, to test its suitability as a high-throughput in vitro model. Benzo[a]pyrene (B[a]P) is an important contaminant and a model polycyclic aromatic hydrocarbon (PAH). Over 48 h exposure, a range of endpoints and xenobiotic metabolism rates were examined at three different pH levels indicative of the in vitro (pH 7.5) and in vivo mid-gut (pH 7.7) and hind-gut (pH 7.4) regions as a function of time. These endpoints included (i) cell viability: acid phosphatase (APH) and lactate dehydrogenase (LDH) assays; (ii) glucose uptake; (iii) cytochrome P450 enzyme activity: 7-ethoxyresoorufin-O-deethylase (EROD) assay; (iv) glutathione transferase (GST) activity; (v) genotoxic damage determined using the comet assay. Absence of cell viability loss, in parallel with decrease in the parent compound (B[a]P) in the medium and its subsequent increase in the cells suggested active sequestration, biotransformation, and removal of this representative PAH. With respect to genotoxic response, significant differences were observed at both the sampling times and the two highest concentrations of B[a]P. No significant differences were observed for the different pH conditions. Overall, this in vitro xenobiotic metabolism system appears to be a robust model, providing a basis for further development to evaluate metabolic and toxicological potential of contaminants without use of animals.
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Affiliation(s)
- Laura M Langan
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, PL4 8AA, UK
| | - Silvia Arossa
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, PL4 8AA, UK
| | - Stewart F Owen
- AstraZeneca, Alderley Park, Macclesfield, Cheshire, SK10 4TF, UK
| | - Awadhesh N Jha
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, PL4 8AA, UK.
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Maunder RJ, Baron MG, Owen SF, Jha AN. Investigations to extend viability of a rainbow trout primary gill cell culture. ECOTOXICOLOGY (LONDON, ENGLAND) 2017; 26:1314-1326. [PMID: 29127661 DOI: 10.1007/s10646-017-1856-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/12/2017] [Indexed: 06/07/2023]
Abstract
The primary culture of fish gill cells can provide functional, cell diverse, model in vitro platforms able to tolerate an aqueous exposure analogous to in vivo tissues. The utility of such models could be extended to a variety of longer term exposure scenarios if a method could be established to extend culture viability when exposed to water for longer periods. Here we report findings of a series of experiments to establish increased longevity, as monitored by culture transepithelial electrical resistance (TEER) and concurrent histological developments. Experimental cultures improved TEER during apical freshwater exposure for a mean of twelve days, compared to previous viabilities of up to 3 days. Cultures with larger surface areas and the use of trout serum rather than foetal bovine serum (FBS) contributed to the improvement, while perfusion of the intact gill prior to cell harvest resulted in a significantly faster preparation. Detailed scanning electron microscopy analysis of cultures revealed diverse surface structures that changed with culture age. Cultures grown on membranes with an increased porosity, collagen coating or 3D structure were of no benefit compared to standard membranes. Increased culture longevity, achieved in this study and reported for the first time, is a significant breakthrough and opens up a variety of future experimentation that has previously not been possible. The extended viability facilitates exploration of in vitro chronic or pulse-exposure test paradigms, longer term physiological and environmental monitoring studies and the potential for interactive co-culture with other organoid micro-tissues.
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Affiliation(s)
- Richard J Maunder
- School of Biological and Marine Sciences, University of Plymouth, Devon, PL4 8AA, UK
| | - Matthew G Baron
- School of Biological and Marine Sciences, University of Plymouth, Devon, PL4 8AA, UK
| | - Stewart F Owen
- AstraZeneca, Alderley Park, Macclesfield, Cheshire, SK10 4TF, UK
| | - Awadhesh N Jha
- School of Biological and Marine Sciences, University of Plymouth, Devon, PL4 8AA, UK.
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14
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Papa E, Sangion A, Arnot JA, Gramatica P. Development of human biotransformation QSARs and application for PBT assessment refinement. Food Chem Toxicol 2017; 112:535-543. [PMID: 28412404 DOI: 10.1016/j.fct.2017.04.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 04/03/2017] [Accepted: 04/10/2017] [Indexed: 12/14/2022]
Abstract
Toxicokinetics heavily influence chemical toxicity as the result of Absorption, Distribution, Metabolism (Biotransformation) and Elimination (ADME) processes. Biotransformation (metabolism) reactions can lead to detoxification or, in some cases, bioactivation of parent compounds to more toxic chemicals. Moreover, biotransformation has been recognized as a key process determining chemical half-life in an organism and is thus a key determinant for bioaccumulation assessment for many chemicals. This study addresses the development of QSAR models for the prediction of in vivo whole body human biotransformation (metabolism) half-lives measured or empirically-derived for over 1000 chemicals, mainly represented by pharmaceuticals. Models presented in this study meet regulatory standards for fitting, validation and applicability domain. These QSARs were used, in combination with literature models for the prediction of biotransformation half-lives in fish, to refine the screening of the potential PBT behaviour of over 1300 Pharmaceuticals and Personal Care Products (PPCPs). The refinement of the PBT screening allowed, among others, for the identification of PPCPs, which were predicted as PBTs on the basis of their chemical structure, but may be easily biotransformed. These compounds are of lower concern in comparison to potential PBTs characterized by large predicted biotransformation half-lives.
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Affiliation(s)
- Ester Papa
- QSAR Research Unit in Environmental Chemistry and Ecotoxicology, Department of Theoretical and Applied Sciences, University of Insubria, Varese Italy.
| | - Alessandro Sangion
- QSAR Research Unit in Environmental Chemistry and Ecotoxicology, Department of Theoretical and Applied Sciences, University of Insubria, Varese Italy
| | - Jon A Arnot
- ARC Arnot Research & Consulting, Toronto, ON Canada; Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON Canada
| | - Paola Gramatica
- QSAR Research Unit in Environmental Chemistry and Ecotoxicology, Department of Theoretical and Applied Sciences, University of Insubria, Varese Italy
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Lillicrap A, Belanger S, Burden N, Pasquier DD, Embry MR, Halder M, Lampi MA, Lee L, Norberg-King T, Rattner BA, Schirmer K, Thomas P. Alternative approaches to vertebrate ecotoxicity tests in the 21st century: A review of developments over the last 2 decades and current status. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2016; 35:2637-2646. [PMID: 27779828 DOI: 10.1002/etc.3603] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 07/21/2016] [Accepted: 08/24/2016] [Indexed: 05/21/2023]
Abstract
The need for alternative approaches to the use of vertebrate animals for hazard assessment of chemicals and pollutants has become of increasing importance. It is now the first consideration when initiating a vertebrate ecotoxicity test, to ensure that unnecessary use of vertebrate organisms is minimized wherever possible. For some regulatory purposes, the use of vertebrate organisms for environmental risk assessments has been banned; in other situations, the number of organisms tested has been dramatically reduced or the severity of the procedure refined. However, there is still a long way to go to achieve a complete replacement of vertebrate organisms to generate environmental hazard data. The development of animal alternatives is based not just on ethical considerations but also on reducing the cost of performing vertebrate ecotoxicity tests and in some cases on providing better information aimed at improving environmental risk assessments. The present Focus article provides an overview of the considerable advances that have been made toward alternative approaches for ecotoxicity assessments over the last few decades. Environ Toxicol Chem 2016;35:2637-2646. © 2016 SETAC.
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Affiliation(s)
- Adam Lillicrap
- Norwegian Institute for Water Research (NIVA), Oslo, Norway.
| | - Scott Belanger
- Environmental Safety and Sustainability, Global Product Stewardship, Procter & Gamble, Mason, Ohio, USA
| | - Natalie Burden
- National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), London, United Kingdom
| | | | - Michelle R Embry
- ILSI Health and Environmental Sciences Institute, Washington, DC, USA
| | | | - Mark A Lampi
- ExxonMobil Biomedical Sciences, Annandale, New Jersey, USA
| | - Lucy Lee
- Faculty of Science, University of the Fraser Valley, Abbotsford, British Columbia, Canada
| | - Teresa Norberg-King
- National Health and Environmental Effects Laboratory, Office of Research and Development, Mid-Continent Ecology Division-Duluth, US Environmental Protection Agency, Duluth, Minnesota, USA
| | - Barnett A Rattner
- Patuxent Wildlife Research Center, US Geological Survey, Beltsville, Maryland, USA
| | - Kristin Schirmer
- Eawag-Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Swiss Federal Institute of Technology, Zürich, Switzerland
- School of Architecture, Civil and Environmental Engineering, EPF Lausanne, Lausanne, Switzerland
| | - Paul Thomas
- Consultancy for Environmental & Human Toxicology & Risk Assessment (Lyon Agency), L'Isle d'Abeau, France
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