Suspect Screening of PFAS in French Coastal Bivalves: In-Depth Detection and Annotation Using Aqueous Film-Forming Foams

Numerous per- and polyfluoroalkyl substances (PFAS) are highly persistent and mobile in the aquatic environment, making the oceans a major sink for contamination. This study presents an in-depth suspect screening of PFAS in marine mussels and oysters from 23 sites along the French coasts, using aqueous film-forming foams (AFFFs) as reference materials. The approach proved effective in revealing precursors that may be metabolized by organisms of higher trophic levels. Overall, 79 PFAS across 29 classes were identified, including 15 classes (e.g., X:2 FTSAm) reported for the first time in marine biota. The use of AFFFs supported not only the detection of PFAS but also their structural annotation, notably by distinguishing per- from polyfluoroalkyl compounds. Several PFAS detected in bivalves, such as 6:2 diPAP and X:3 FTCA, were not found in AFFFs, which suggested the existence of alternative sources and/or environmental degradation processes. Spatial analysis revealed contrasting contamination profiles, in particular PFAS hotspots near industrialized and estuarine areas, and lower levels at less-industrialized sites or those further from the coast. Detection of currently unmonitored PFAS (e.g., 6:2 FTAB and FHxSA) at all sampling sites highlighted the urgent need to broaden the scope of PFAS studies for a more comprehensive environmental assessment.