Rapid Hazard Profiling of Emerging Contaminants in the French Broad River Post-Hurricane Helene

Extreme weather events are increasingly impacting freshwater systems, yet timely chemical hazard assessments in their aftermath remain scarce. This study applied a rapid hazard profiling approach to characterize organic contaminants in the French Broad River, North Carolina, following historic flooding from Hurricane Helene. Sur-face water samples were collected from five sites along an 80-kilometer stretch of the river 15 days post-storm and analyzed using liquid chromatography–high-resolution mass spectrometry. Targeted analysis quantified 11 per- and polyfluoroalkyl substances, while non-targeted analysis (NTA) and suspect screening detected 468 compounds across multiple confidence levels. Hazard screening via the EPA cheminformatics module suggested medium to very high toxicity potential for many compounds: 64% were suspected acute aquatic toxicants, 58% posed human developmental risks, 23% were classified as endocrine disruptors, 12% as reproductive toxicants, and 10% as known or suspected carcinogens. At one downstream site, concentrations of PFOS and PFOA exceeded EPA maximum contaminant levels for drinking water. Site-specific contaminant profiles by chemical class (PFAS, pesticides, plastic additives, pharma-ceuticals) indicated contributions from flood-damaged wastewater infrastructure and plastic debris. These findings highlight the vulnerability of freshwater systems to con-taminant mobilization during extreme floods and demonstrate the utility of integrated NTA and cheminformatics for rapid post-disaster monitoring. This supplementary dataset includes the raw data files associated with targeted quantitation, nontargeted analysis, and cheminformatic hazard assessments.