Abstract
No-observed-effect concentrations (NOECs) are used in environmental hazard classification and labeling of chemicals and their environmental risk assessment. They are typically obtained using standard tests such as the fish early-life stage (FELS) toxicity test, the chronic Daphnia reproduction test, and the algae growth inhibition test. Given the demand to replace and reduce animal tests, we explored the impact of the FELS toxicity test on the determination of effect concentrations by comparing the FELS toxicity test and the Daphnia and algae acute or chronic toxicity tests. Lowest-observed-effect concentrations (LOECs) were used instead of NOECs for better comparison with median lethal or effect concentration data. A database of FELS toxicity data for 223 compounds was established. Corresponding Daphnia and algae toxicity tests were identified using established databases (US Environmental Protection Agency ECOTOX, Organisation for Economic Co-operation and Development QSAR Toolbox, eChemPortal, EnviroTox, and OpenFoodTox). Approximately 9.5% of the investigated compounds showed a 10-fold higher sensitivity with the FELS toxicity test in comparison with the lowest effect concentrations obtained with any of the other tests. Some of these compounds have been known or considered as endocrine disrupting, or are other non-narcotic chemicals, indicating that the higher sensitivity in the FELS toxicity test is related to a specific mechanism of action. Targeting these mechanisms by alternative test systems or endpoints, using fish embryos for instance, may allow reduction or replacement of the FELS toxicity test or may allow us to prioritize compounds for conduction of the FELS toxicity test. Environ Toxicol Chem 2019;39:30-41. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
Highlights
For the environmental hazard and risk assessment of industrial chemicals, biocides and plant protection products, TER or Predicted no effect concentrations (PNECs) are calculated
Given the demand to replace and reduce animal tests we explored the impact of the fish early-life stage (FELS) test on the PNEC by comparing the sensitivity of the FELS test to daphnia and algae acute or chronic toxicity tests
Since four of these chemicals have been already tested in other studies included in the existing dataset, the update added a total number of 69 chemicals to the existing FELS test database
Summary
For the environmental hazard and risk assessment of industrial chemicals, biocides and plant protection products, TER (toxicity exposure ratios) or PNECs (predicted no effect concentrations) are calculated. Enhanced toxicity (i.e. effect concentrations below baseline toxicity levels and a high acute-to-chronic ratio) was caused by compounds with a specific or reactive mode of action such as neuromuscular toxicity, methemoglobin formation, extracellular matrix inhibition or endocrine disruption (Scholz et al, 2018). Some of these MoAs may be captured by alternative endpoints such as behavior or phenotypic assessment in the fish embryo test (FET, OECD TG 236 (OECD, 2013)) and could be used to predict the chronic fish toxicity appropriately. In the context of a comparative assessment with daphnia and algae test, the FELS test may not represent the most sensitive test and even for compounds with a specific MoA the FELS test may exhibit a weak impact on the TER and PNEC assessment and subsequent labeling and classification of products with regard to their environmental hazard
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