U.S. Environmental Protection Agency Office of Research and Development • The concentration of both volatile and non-volatile PFAS can be measured in the RBT liver slice assay. • Perfluoroalkyl carboxylic acids (PFBA, PFPeA, PFHxA, PFHpA, PFOA) were not metabolized by RBT liver slices. • The fluorotelomer carboxylic acid, 4:3 FTCA, was not metabolized by RBT liver slices. • There was significant loss of 6:2 FTCA in the presence of slices, suggesting possible metabolism. Further investigation is needed to verify this observation as metabolism. • The fluorotelomer alcohols 4:1 FTOH and 4:2 FTOH were not metabolized by RBT liver slices. • There was significant loss of 6:2 FTOH and 8:2 FTOH in the presence of slices in multiple tests, suggesting possible metabolism. Further investigation is needed to verify this as metabolism. OH F F F F F F F F F F F F F F F F F OH OH OH HO O O O F F F F F F F F F F F F F F F F F OH O F F F F F F F F F F F F F F F F F 8:2 FTOH 8:2 FTOH - Glucuronide O F F F F F F F F F F F F F F F F 8:2 FTUAL 8:2 FTCA OH O F F F F F F F F F F F F F F F F 8:2 FTUCA OH O F F F F F F F F F F F F F F F 7:3 FTCA O O F F F F F F F F F F F F F F F OH O F F F F F F F F F F F F F F F 7:3 beta-keto aldehyde PFOA NH2 O NH S OH F F F F F F F F F F F F F F F O NH OH O OH O 8:2 uFTOH - GS OH O F F F F F F F F F OH O F F F F F F F F F F F OH O F F F F F F F F F F F F F OH O F F F F F F F F F F F F F F F F F PFPeA PFHxA PFHpA PFNA The views expressed in this poster are those of the authors and do not necessarily reflect the views or policies of the U.S. EPA • Per-and Polyfluoroalkyl Substances (PFAS) are contaminants of emerging concern because of • Wide distribution • Resistance to degradation • Potential adverse health outcome • There is a need for a greater understanding of the fate and effects of these chemicals within organisms regarding •Bioaccumulation •Metabolism •Toxicity • Most of the existing PFAS metabolism literature pertains to mammalian species. Little is known regarding the activity of PFAS in non mammalian species, such as fish. • The rainbow trout (RBT) liver slice assay has been successfully used to study chemical metabolism of chemical classes other than PFAS. • Metabolic Pathways Knowledgebase Platform (MetaPath) uses a systematic process for compiling metabolism map information from across the open literature to build metabolism databases. Introduction Parent Chemical Screening Results Acknowledgements Sara Mary Daley l Daley.Sara.M@epa.gov l 218-529-5187 Metabolism of per- and polyfluoroalkyl substances (PFAS) in rainbow trout (Oncorhynchus mykiss) using an ex vivo model. Sara M. Daley1, Jose Serrano2, Richard Kolanczyk2, Mark Tapper2 1Oak Ridge Institute for Science and Education Research Participant, Oak Ridge, TN, USA 2U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, MN, USA References We thank Tylor Lahren for assistance in operating the LC-MS (USEPA/ORD/CCTE), Megan Saley (ORISE) for assistance in preparing samples, and Evan Timmerman for maintenance of fish cultures. This project was supported in part by an appointment to the Research Participation Program at the Office of Research and Development Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and EPA. Conclusions Objectives Han J. et al. A Roadmap to the Structure-Related Metabolism Pathways of Per- and Polyfluoroalkyl Substances in the Early Life Stages of Zebrafish (Danio rerio). Environmental Health Perspectives 2021. Nabb D. et al. In Vitro Metabolism of 8-2 Fluorotelomer Alcohol: Interspecies Comparisons and Metabolic Pathway Refinement. Toxicological Sciences 2007. Kolanczyk R. et al. MetaPath: An electronic knowledge base for collating, excha