EVALUATING HIGH-THROUGHPUT ASSAYS FOR PESTICIDE ECOLOGICAL RISK ASSESSMENT

Evaluating the ecological risk of pesticides is crucial for regulatory decision-making, yet traditional vertebrate-based approaches are time-consuming, costly, and ethically challenging. New approach methodologies (NAMs), such as high-throughput assays (HTAs), offer cost-effective alternatives that are more time and cost efficient, while also reducing reliance on animal testing. The US Environmental Protection Agency’s ToxCast program generates HTA data for chemical screening, but its applicability to ecological risk assessment remains underexplored. In this study, I applied ToxCast data directly to ecological risk assessment metrics, comparing assay-derived exposure-activity ratios (EARs) to in vivo risk quotients (RQs) used in regulatory decision-making. Uniquely, this study focuses on pesticides and is risk-focused rather than hazard-focused, leveraging data drawn directly from the same standardized regulatory risk assessments that inform decision-making. This ensures both consistency within the study and practical relevance to regulation procedures, providing a framework for advancing the use of HTAs in ecological risk assessment. While ToxCast assays generally underestimated risks compared to in vivo RQs – particularly for chronic endpoints – certain assays, such as cytochrome P450 (CYP) enzyme assays, demonstrated strong alignment for herbicides and fungicides. In contrast, assay performance was weaker for neurotoxic insecticides and herbicides targeting photosynthesis, reflecting gaps in HTA coverage for these modes of action. My findings underscore the potential of HTAs as complementary tools for ecological risk assessment, particularly for screening and prioritization, while emphasizing the need for further assay development to address chronic and mode-of-action-specific risks. These findings also highlight the potential for using HTA procedures to evaluate the environmental risk of neonicotinoids. By integrating HTA data into regulatory risk metrics, this study provides a foundation for advancing NAMs in pesticide regulation and promoting more resource-efficient and ethical approaches to environmental protection.

Author

• Sattler, Leah

• Pesticides
• In vitro to in vivo extrapolation
• New Approach Methodologies
• Ecological Risk Assessment

Identifier

hdl:1920/14654

OAI identifier oai:identifier

oai:MARS:1920/14654