Multi-media occurrence, bioaccumulation, and exposure assessment of PFAS across a Midwestern U.S. State

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants of global concern, yet integrated, multi-compartment assessments at the regional scale remain limited. Here, we present a cross-media evaluation of PFAS occurrence, distribution, bioaccumulation, and exposure across Indiana, a midwestern United States state characterized by mixed industrial, urban, and agricultural land use. Detection relied on a combination of targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) and emerging electrochemical sensor approaches to capture both known and previously unmonitored PFAS. Atmospheric deposition data indicate the presence of both legacy and emerging PFAS, including ultra-short-chain compounds that dominate wet deposition profiles. Analysis of 473 Indiana public water systems (2021-2024) revealed detectable PFAS in 15.4% of treated drinking water systems, with 1.9% exceeding proposed maximum contaminant levels; larger systems and areas with higher proportions of minority residents were more likely to report detections. Statewide fish monitoring (n = 940 samples, 44 species) demonstrated substantial bioaccumulation, with perfluorooctanesulfonic acid (PFOS) comprising ∼69% of total PFAS burden and multiple counties exceeding consumption advisory thresholds. Preliminary human serum biomonitoring confirmed widespread exposure to a broad spectrum of legacy and replacement PFAS. Bench-scale treatment tests conducted in the state showed high removal efficiencies for selected PFAS using activated carbon under pre-breakthrough conditions, while evaluation of fluorine-free firefighting foam alternatives revealed performance trade-offs relative to PFAS-based formulations. Collectively, these findings demonstrate that PFAS contamination in Indiana spans atmospheric, aquatic, biological, and human compartments, highlighting interconnected exposure pathways and the need for integrated monitoring and mitigation strategies. This statewide assessment provides a model for evaluating PFAS contamination in regions with diverse land use and industrial activity.