Assessment of legacy and emerging per- and polyfluoroalkyl substances (PFAS) in drinking water from historic industrial and neighboring communities

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants increasingly detected in drinking water worldwide. In this study, municipal tap water and bottled water samples collected from seven communities in Madison County, Illinois, USA were analyzed for PFAS. A total of 16 PFAS analytes were detected in the tap water samples at concentrations ranging from 1.0 to 19.4 ng/L. PFAS levels in all bottled water samples were below the minimum reporting level of 1.0 ng/L. Perfluorobutanoic acid (PFBA), perfluorobutane sulfonic acid (PFBS), perfluorooctane sulfonic acid (PFOS), and perfluoropentanoic acid (PFPeA) were detected in every community tap water, while perfluorobutane sulfonamide (FBSA), perfluorohexane sulfonamide (FHxSA), perfluoro-4-ethylcyclohexane (PFECHS), and perfluoropropane sulfonic acid (PFPrS) were uniquely detected in one community tap water. PFBS was the most prevalent PFAS detected in 87% of all water samples. Short-chain PFAS were more frequently detected in tap water than long-chain PFAS. Overall, 27% of all tap water samples exceeded federal drinking water standards for PFAS. Perfluorooctanoic acid (PFOA) and PFOS concentrations in tap water exceeded the U.S. EPA’s enforceable maximum contaminant level of 4 ng/L in three communities, where the Illinois EPA has reported high levels of PFAS in community water supplies. While PFAS profiles in each community's tap water in this study were generally consistent with the Illinois EPA statewide study, our study identified a greater number of PFAS. The hazard index, calculated for PFBS, perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) in tap water for each community did not exceed the U.S. EPA’s safety threshold. PFAS occurrence, diversity, and exceedance of regulatory limits were substantially higher in groundwater-sourced systems than in surface water-sourced systems. Cluster analysis of PFAS profiles revealed close relationships between neighboring communities with similar industrial activities. Tap water from legacy industrial towns and aging infrastructure neighborhoods recorded high levels of PFAS. Our study highlights the widespread occurrence of PFAS contamination in drinking water across the United States.