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Beyond the watchlist: How the TOP assay exposes untargeted PFASs for current and future regulations in consumer
Christophe Bleuler1, Tania Bernardez1, Vanessa Inderbitzin1
1Service de l'air, du Bruit et des Rayonnements Non ionisants (SABRA), Geneva Cantonal Office for the Environment, 1205, Geneva, Switzerland.
Abstract:
Due to human exposure and environmental risks, per- and polyfluoroalkyl substances (PFASs) in commercial products are subject to increasingly stringent and worldwide regulations. In this study, impregnation products (n = 25), textiles (n = 15) and food contact materials (n = 18), mainly from the Swiss market, were selected for their water- or grease-proof capabilities and assessed for the presence of PFASs. Total fluorine was detected in 52 % of impregnation products, 87 % of textiles, and 61 % of food contact materials by combustion ion chromatography. A targeted analysis of perfluoroalkyl carboxylic acids (PFCAs), sulfonic acids (PFSAs), and fluorotelomer sulfonates (FTSs) resulted in individual PFASs concentrations that were all below 165 ppb. The application of a modified total oxydizable precursor (TOP) assay to the samples enabled the transformation of oxidizable precursors, including side-chain fluorinated polymers, into PFCAs, with average increases in concentrations of the targeted PFASs in fluorine equivalents by a factor of 23 600 for impregnation products, 1300 for textiles, and 420 for food contact materials. The PFCA fingerprints were dominated by short C6 chains, which are currently being restricted by national and international regulations. In this context, applying the TOP assay uncovered a significant proportion of samples with precursors providing perfluorohexanoic acid (PFHxA) concentrations above the 1000 ppb threshold, compared to a direct PFASs targeted approach. While providing a snapshot of the current market situation, this study demonstrates the usefulness of a TOP assay for enforcing regulatory compliance. It also highlights the prevalence of short-chain PFASs in commercial products despite the availability of fluorine-free alternatives.
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