Per- and polyfluoroalkyl substances (PFAS) are a chemical class of highly fluorinated anthropogenic chemicals. Exposures to perfluoroalkyl compounds have been linked to numerous adverse hepatic and immunological outcomes. Polyfluoroalkyl compounds, which can degrade into perfluoroalkyl compounds and share similar chemical properties, have received minimal scientific and regulatory attention. Extensive use of the polyfluoroalkyl 6:2 fluorotelomer sulfonate (6:2 FTSA) and its precursors (6:2 FT) in aqueous film-forming foams (AFFF) and mist suppressants used in metal plating has resulted in widespread contamination of groundwater and waste infrastructure. Critical gaps in understanding of the disposition of these chemicals in vitro, their metabolites, possible health effects, and potential contributions to the human body burden of perfluoroalkyl carboxylic acids (PFCA) hinder ongoing risk assessment. This proposal aims to address these gaps by measuring these compounds, and their metabolites, in CD-1 mice exposed to 6:2 FTSA and 6:2 FT mixtures used in AFFF. Our team will first evaluate PFAS bioaccumulation and metabolic pathways for PFCA production in these mice. The mice will be exposed for 28 days to 10 µM F 6:2 FTSA or AFFF via oral gavage and levels of PFAS and extractable organofluorine (EOF) will be quantified in serum, liver, and other organs using liquid chromatography tandem mass spectroscopy and combustion ion chromatography. Total protein, lipids, and phospholipids will be simultaneously measured to assess distribution among tissues using a mixed effects model. Nontargeted analysis using high resolution mass spectroscopy will be performed to identify unknown metabolites and degradation mechanisms. A follow-up study will be performed to assess dose-response relationships during developmental and chronic exposure to 6:2 FTSA in the mice. Pregnant mice will be exposed to 0 to 1 µM F as 6:2 FTSA via oral gavage and their pups will be split into acute (PFAS free) or chronic (0.001 µM F as 6:2 FTSA) exposure groups. PFAS and EOF will be quantified in the mothers’ breast milk and the pup’s serum and liver at postnatal day 4, 21, and 126.