Reaction to the short communication by Ghose et al

Critical Review of Read-Across Potential in Testing for Endocrine-Related Effects in Vertebrate Ecological Receptors

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.

Lethal toxicity of the herbicides acetochlor, ametryn, glyphosate and metribuzin to tropical frog larvae

Despite the high amphibian biodiversity and increasing pesticide use in tropical countries, knowledge on the sensitivity of tropical amphibians to pesticides remains limited. The aim of this study was to evaluate the acute toxicity of the active ingredients of four of the main herbicides used in Brazilian sugarcane production to tadpoles of two tropical frog species: Physalaemus cuvieri and Hypsiboas pardalis. The calculated 96 h-LC50 (median lethal concentration; in mg a.s./L) values for P. cuvieri and H. pardalis were 4.4 and 7.8 (acetochlor); 15 and <10 (ametryn); 115 and 106 (glyphosate); and 85 and 68 (metribuzin), respectively. These toxicity values demonstrated little interspecies variation and the toxicity of the herbicides appeared to be at least partly related with the respective octanol-water coefficient. Published acute toxicity data of fish and amphibians for herbicides were also compiled from the US-EPA ECOTOX database. These data indicated little difference in herbicide sensitivity between tropical amphibians and both non-tropical amphibians and fish. These findings indicate that temperate (fish and amphibian) herbicide toxicity data are also protective for tropical amphibians. Constraints in such extrapolations and indications for future research are discussed.

Scientific Opinion on the state of the science on pesticide risk assessment for amphibians and reptiles

Following a request from EFSA, the Panel on Plant Protection Products and their Residues developed an opinion on the science to support the potential development of a risk assessment scheme of plant protection products for amphibians and reptiles. The coverage of the risk to amphibians and reptiles by current risk assessments for other vertebrate groups was investigated. Available test methods and exposure models were reviewed with regard to their applicability to amphibians and reptiles. Proposals were made for specific protection goals aiming to protect important ecosystem services and taking into consideration the regulatory framework and existing protection goals for other vertebrates. Uncertainties, knowledge gaps and research needs were highlighted.