PROJECT SUMMARY/ABSTRACT More than 600 sites across the U.S. are contaminated by poly and perfluroalkyl substances (PFASs) but the extent of transport away from these sites and entry into human exposure pathways (drinking water and fish) is virtually unknown. This information is critical for assessing human health risks associated with exposures to PFASs from contaminated sites, such as the metabolic and immune outcomes that are being investigated in Projects 2 and 3 of the STEEP Center. This project will measure a suite of PFASs present in drinking water and fish near the Joint Base Cape Cod (JBCC), a region contaminated by historical fire training activity and designated as a National Priorities List site. For Aim 1, novel statistical methods will be used to fingerprint profiles of PFASs measured in fish and drinking water around the JBCC site. PFAS profiles in drinking water and fish will be compared to those from consumer products (wastewater influent) to identify exposures originating from contaminated sites. For Aim 2, we will leverage from long-term research by the U.S. Geological Survey (USGS) near the JBCC site characterizing hydrological flow paths and groundwater geochemistry to better understand how environmental factors influence the transport and transformations of PFASs away from contaminated sites and into drinking water supplies. We will use a combination of field measurements in collaboration with Project 4, and advanced geochemical modeling that leverages from prior USGS hydrological research. For Aim 3, we will extend knowledge on the spatial domain of groundwater transport to include uptake by fish. Fish will be exposed to experimental incubations along the groundwater transport plume and we will assess toxicological biomarkers for immune and metabolic responses. One of the major expected outcomes of this work will be better understanding of the spatial extent of elevated PFAS concentrations in fish and drinking water from contaminated sites, which will allow improved characterization of exposed populations and risks. This project will provide a novel contribution at the nexus between geochemistry and health by linking the geochemical factors affecting PFAS transport and mobility to human health risks associated with exposure. !