Abstract-Acute toxicity data from the New Chemicals Database of the European Chemicals Bureau were compared for fish, Daphnia, and algae. The algal growth inhibition test was the most sensitive. Correlation between fish and Daphnia toxicity values was better than the correlation with algae. Toxicity values among the three organisms correlated more strongly than any with log P ow .

Recent regulatory testing programs have been designed to evaluate whether a chemical has the potential to interact with the endocrine system and could cause adverse effects. Some endocrine pathways are highly conserved among vertebrates, providing a potential to extrapolate data generated for one vertebrate taxonomic group to others (i.e., biological read‐across). To assess the potential for biological read‐across, we reviewed tools and approaches that support species extrapolation for fish, amphibians, birds, and reptiles. For each of the estrogen, androgen, thyroid, and steroidogenesis (EATS) pathways, we considered the pathway conservation across species and the responses of endocrine‐sensitive endpoints. The available data show a high degree of confidence in the conservation of the hypothalamus–pituitary–gonadal axis between fish and mammals and the hypothalamus–pituitary–thyroid axis between amphibians and mammals. Comparatively, there is less empirical evidence for the conservation of other EATS pathways between other taxonomic groups, but this may be due to limited data. Although more information on sensitive pathways and endpoints would be useful, current developments in the use of molecular target sequencing similarity tools and thoughtful application of the adverse outcome pathway concept show promise for further advancement of read‐across approaches for testing EATS pathways in vertebrate ecological receptors. Environ Toxicol Chem 2020;39:739–753. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Risk assessment approaches within the regulatory framework of the European Union (EU) based on single species tests were compared to those using data from terrestrial model ecosystems (TMEs). In a case study with the fungicide carbendazim, single species data led to ratios of the predicted environmental concentration (PEC) and predicted no effect concentration (PNEC) of above 1000, depending on available data and related assessment factors, indicating concern for the terrestrial environment. Considering the high degree of realism of the TME studies with multiple endpoints measured, but also residual uncertainty related to higher variability of endpoints, an assessment factor of 5 was applied on TME data. The most sensitive reliable endpoint was earthworm biomass. With the TME studies yielding slightly higher effect thresholds compared to laboratory data, and due to the lower assessment factor, the PEC/PNEC ratio was lowered to 5. This means that there would be concern for high application rates of carbendazim.

Fate and toxicity of the active ingredients (AI's) of plant protection products in surface waters is often influenced by pH. Although a general range of pH values is reported in literature, an evaluation targeting aquatic ecosystems with documented AI inputs is lacking at the larger scale. Results show 95% of European surface waters (n = 3075) with a documented history of AI exposure fall within a rather narrow pH range, between 7.0 and 8.5. Spatial and temporal variability in the data may at least be partly explained by the calcareous characteristics of parental rock material, the affiliation of the sampling site to a freshwater ecoregion, and the photosynthetic activity of macrophytes (i.e., higher pH values with photosynthesis). Nonetheless, the documented pH range fits well with the standard pH of most ecotoxicological test guidelines, confirming the fate and ecotoxicity of AIs are usually adequately addressed.

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