Evaluating the Functional Equivalency of Test Organism Performance in Negative and Solvent Controls During Chronic Sediment Ecotoxicity Studies Based on US Environmental Protection Agency Guidance

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Abstract

The US Environmental Protection Agency (USEPA) considers sediment toxicity tests as conditional registration requirements for pesticides with soil Kd ≥50 L/kg-solid, Koc ≥1000 L/kg-organic carbon, or log Kow ≥3. The hydrophobicity of these compounds often necessitates use of solvents to ensure accurate and homogeneous dosing of spiked-sediment studies. For sediment tests, a volatile solvent (e.g., acetone) is generally used as a transient carrier. Due to low water solubility, test material is dissolved in a volatile solvent to create stock solutions. A measured aliquot of stock solution is then mixed with sand substrate, after which the solvent is evaporated. This spiking process results in negligible solvent exposure to organisms. In 2016, USEPA released final ecotoxicity test guidelines for subchronic freshwater (850.1735) and marine (850.1740) sediment test. These methods provide an option for conducting experiments with only a solvent control and no negative control. To adopt this testing strategy, functional equivalency between the negative and solvent control must be demonstrated. These test guidelines describe specific factors that should be considered for evaluating functional equivalency, including (a) the concentration of solvent in the test sediment after evaporation, (b) the levels of solvent that are known to affect organism health, (c) the known impurities in the solvent and their potential impact on organism health, and (d) the historical organism performance of solvent versus negative controls. Our analysis considers these factors and overall supports the elimination of the negative control requirement because this change is unlikely to impact the robustness or interpretability of spiked-sediment toxicity tests. Environ Toxicol Chem 2023;00:1–7. © 2023 CropLife America. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Big Question to Developing Solutions: A Decade of Progress in the Development of Aquatic New Approach Methodologies from 2012 to 2022

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Abstract

In 2012, 20 key questions related to hazard and exposure assessment and environmental and health risks of pharmaceuticals and personal care products in the natural environment were identified. A decade later, this article examines the current level of knowledge around one of the lowest-ranking questions at that time, number 19: “Can nonanimal testing methods be developed that will provide equivalent or better hazard data compared with current in vivo methods?” The inclusion of alternative methods that replace, reduce, or refine animal testing within the regulatory context of risk and hazard assessment of chemicals generally faces many hurdles, although this varies both by organism (human-centric vs. other), sector, and geographical region or country. Focusing on the past 10 years, only works that might reasonably be considered to contribute to advancements in the field of aquatic environmental risk assessment are highlighted. Particular attention is paid to methods of contemporary interest and importance, representing progress in (1) the development of methods which provide equivalent or better data compared with current in vivo methods such as bioaccumulation, (2) weight of evidence, or (3) -omic-based applications. Evolution and convergence of these risk assessment areas offer the basis for fundamental frameshifts in how data are collated and used for the protection of taxa across the breadth of the aquatic environment. Looking to the future, we are at a tipping point, with a need for a global and inclusive approach to establish consensus. Bringing together these methods (both new and old) for regulatory assessment and decision-making will require a concerted effort and orchestration. Environ Toxicol Chem 2023;00:1–15. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.