PFAS contamination and risk assessment at an AFFF production site in China: Signatures of fluorosurfactant feedstocks.

The extensive use of fluorinated aqueous film forming foams (AFFF) in firefighting is a primary source of per and polyfluoroalkyl substances (PFAS) contamination. However, data on PFAS contamination at AFFF manufacturing sites remains limited. In this study, we selected a AFFF manufacturing plant with over 30 years of operational history to characterize its PFAS contamination profile. We quantified 31 PFAS in key industrial samples (AFFF concentrates and fluorosurfactants (FS) feedstocks) and environmental samples (wastewater, soil, groundwater, and surface water) from the site, and assessed the associated environmental risks. Notably, 6:2 fluorotelomer sulfonate (6:2 FTS) was the predominant component in FS (83.72-92.94 mg/L), AFFF foam concentrates (1.11-13.96 mg/L), and wastewater (2.55 μg/L). In the environmental matrices (soil, groundwater, and surface water), 6:2 FTS, perfluorooctanesulfonic acid (PFOS), and sodium perfluorononyloxybenzenesulfonate (OBS) were detected at elevated concentrations. The total oxidizable precursors (TOP) assay revealed that the primary oxidation products in the industrial samples were short chain perfluoroalkyl carboxylic acids (PFCA, C4-C7), with total PFCA concentrations increasing by 1-3 orders of magnitude post-oxidation. Although PFOS-based AFFF is no longer manufactured or used in China, historically-released PFOS persists at the site. Furthermore, soil PFOS concentrations exceed U.S. EPA's human health guidance values, indicating significant human health risks. For the ecological risk assessment, the acute risk quotient (RQ) for PFOS in soil and surface water samples was below 0.06, whereas the maximum chronic RQ reached 25.29, suggesting that while acute ecological risk is negligible, a substantial chronic ecological risk persists.