Target and non-target screening of per- and polyfluoroalkyl substances (PFAS) in drinking water: Focus on alternatives and health risks

The persistent environmental presence of per- and polyfluoroalkyl substances (PFAS) in aquatic systems has raised concerns regarding their potential threat to drinking water safety. However, our understanding of PFAS distribution within drinking water systems remains limited. This study employed a combination of targeted, suspect, and non-targeted screening techniques to investigate the distribution of PFAS in 16 drinking water treatment plants (DWTPs) supplied by two distinct water sources: the Yangtze River and Lake Taihu and its surrounding water bodies. Specifically, four DWTPs using Yangtze River water were monitored throughout the four seasons, with samples collected from source water, critical points in the treatment process, and treated water. Twelve DWTPs using Lake Taihu and surrounding water sources were examined cross-sectionally, with samples collected from treated water and tap water. The results showed that total PFAS in the Lake Taihu-sourced systems exhibited inflection points at the 30th and 90th percentiles, unlike the more uniform distribution of PFOS + PFOA. This suggests contributions from both consumer and industrial sources of PFAS alternatives. Suspect and non-targeted screening identified 27 positive features, of which 10 were not detected in the targeted analysis, thereby broadening the scope of PFAS detection in drinking water. Furthermore, the relative potency factor (RPF) method was used to estimate the cumulative toxicity of PFAS mixtures, including alternatives, by calculating the perfluorooctanoic acid equivalent (PEQ). Computational toxicology and molecular dynamics (MD) simulations were employed to identify the toxicity targets of these alternatives, revealing the potential toxicity of 6:2FTSA in relation to the blood-brain barrier (BBB) basement membrane and glucose transport functions. This study reveals that alternative PFAS are commonly found in drinking water systems and pose potential health risks that warrant serious attention.