Development of new approach methodologies for evaluating acute toxicity, chronic toxicity, and endocrine disruption

Allen, Dalton

Item

Development of new approach methodologies for evaluating acute toxicity, chronic toxicity, and endocrine disruption

Allen, Dalton

Date

2025-04-25

Abstract

Recent legislation has called for the development and implementation of new approach methodologies that promote the 3Rs of animal research. This project addressed this need in three core areas: 1) the assessment of effluents discharged into marine environments, 2) assessment of endocrine disrupting compounds in freshwater environments, and 3) assessment of endocrine disrupting compounds in marine environments. For the first aim, this study compared marine larval growth and survival (LGS) tests using sheepshead minnow and inland silversides with marine fish embryo toxicity (FET) tests and mysid shrimp tests across multiple chemicals (3,4 dichloroaniline, Ni, phenanthrene, and crude oil spiked with V). Mysid shrimp tests demonstrated comparable or greater sensitivity than LGS tests, while marine FET tests were generally less sensitive. However, incorporating sublethal endpoints, especially hatchability, improved the sensitivity of FET tests. For the second aim, this work validated the REACTIV assay for screening endocrine disrupting chemicals (EDCs), using a suite of chemicals (17β estradiol (E2), testosterone, fadrozole, flutamide, trenbolone (Trb), and saccharin). The REACTIV assay successfully identified pro- and anti-estrogenic compounds while distinguishing inert compounds. For the third aim, the potential of mysid shrimp as a model for assessing vertebrate EDCs (E2 and Trb) was examined in relation to the ecdysteroid, ponasterone A. Neither vertebrate EDC induced effects similar to ponasterone A, but Trn significantly downregulated ecdysteroid-related gene expression. Broader transcriptomic analysis identified differentially expressed genes that may serve as biomarkers for assessing invertebrate endocrine disruption. Overall, the findings of this work contribute to the advancement of animal welfare in aquatic toxicity assessments.