Reducing animal use in ecotoxicity testing and biomonitoring
DOI scientists at multiple USGS science centers continue to advance ecotoxicity testing and biomonitoring methods that reduce reliance on animals in environmental assessments. This work emphasizes NAMs that provide innovative, nonanimal tools for understanding how emerging contaminants affect fish and wildlife health. State and federal agencies are already applying these findings in decision-making and environmental management. Collectively, these efforts demonstrate practical applications of in vitro, in silico, and noninvasive tools that support ecological decisions and minimize animal handling, disturbance, and stress.
- USGS is currently conducting research on stressor–response relationships in aquatic species, including studies of stormwater-derived toxicants, such as 6PPD-quinone (a tire wear transformation product), and the evaluation of alternative compounds with reduced toxicological impact. Pacific salmon (Onchorychus spp.) cell line assays allow rapid, mechanistic screening of potential 6PPD substitutes. These assays reduce the need for animal models and can provide detailed insights into immune, metabolic, and cellular pathways affected by tire wear chemicals. Complementary efforts support the development of Bigg’s killer whale (Orcinus orca rectipinnus) cell lines as surrogate in vitro systems for assessing risks posed by persistent organic pollutants to endangered Orca populations. Together, these NAM-based approaches strengthen DOI’s capacity to deliver decision-relevant science for species conservation and ecosystem health under the One Health paradigm.
- USGS and EPA are jointly conducting a multiphase transcriptomic zinc toxicity study using zebrafish (Danio rerio) and medaka (Oryzias latipes). Through iterative experimentation, the partnership is generating robust mechanistic datasets that improve EPA’s metals assessment processes and advance USGS’s function to develop modern mechanistic tools for ecological toxicology.
- USGS scientists are also participating in an international ring test aimed at standardizing the zebrafish dark/light transition test, a widely used locomotor assay for detecting subtle neurobehavioral effects of chemical exposure. Because laboratories currently employ diverse protocols, exposure conditions, and analytical approaches, cross-study comparison is challenging. The ring test evaluates both technical and biological variability and develops harmonized procedures to improve reproducibility and consistency. By reducing variability and establishing standardized methods, this work directly supports ICCVAM’s goals of advancing reliable, fit-for-purpose NAMs suitable for regulatory consideration.
- From a biomonitoring standpoint, USGS researchers continue to use environmental DNA as a noninvasive method for detecting sensitive or imperiled aquatic species, such as freshwater mussels and state-listed darters, without requiring physical capture or intrusive field procedures. By enabling efficient, low-impact survey methods, environmental DNA functions as a NAM aligned with ICCVAM’s goals of reducing animal use while supporting robust ecological data collection for management and conservation decisions.