In an article published on January 31, 2026, in the journal Chemosphere, Christophe Bleuler from the Geneva Cantonal Office for the Environment, Switzerland, and co-authors demonstrate the importance of testing for per- and polyfluoroalkyl substances (PFASs) precursors in regulatory compliance testing.
The authors analyzed PFAS concentrations in 18 food contact materials (FCMs), 25 impregnation products, and 15 textiles, mostly from the Swiss market. They quantified the total fluorine content using Combustion Ion Chromatography (CIC) and performed targeted analyses of 21 PFASs by liquid chromatography-mass spectrometry (LC-MS/MS). Importantly, targeted analysis was conducted both before and after applying the total oxidizable precursor (TOP) assay. The TOP assay oxidizes precursors of perfluoroalkyl carboxylic acids (PFCAs), including those not detectable through targeted analysis, into detectable PFCAs, thus providing a more realistic picture of the total PFASs burden in consumer products.
The scientists detected fluorine in 61% of the FCMs, with levels ranging from 5-118 in μg F/cm2 FCM (290 to 2500 ppm). They considered products with total fluorine above 100 ppm to contain intentionally added PFASs. Before the TOP assay, targeted analysis showed low PFAS levels, mostly in the sub‑ppm range. The short‑chain PFCAs perfluorohexanoic acid (PFHxA, CAS 307-24-4) and perfluorobutanoic acid (PFBA, CAS 375-22-4) were the most frequently detected, occurring in 39% and 22% of FCMs, respectively.
After the TOP assay, detectable PFAS levels increased 420-fold. Across all product categories, the short- chain PFHxA and precursors dominated the PFCA profiles, substances that have been restricted by EU’s chemicals regulation REACH and the Swiss Ordinance on the Reduction of Risks relating to the Use of Certain Particularly Dangerous Substances, Preparations and Articles (ORRChem). After performing the TOP assay, 50% of FCMs were non‑compliant with these regulations, compared to 11% before the assay. In addition, among the FCM samples that fall under the packaging definition of the EU Packaging and Packaging Waste Regulation (PPWR), 43% would exceed the regulation’s total fluorine limit of 50 ppm, which is set to be implemented in August 2026, the researchers reported (FPF reported). Similar restrictions are prepared in Switzerland. The European Chemicals Agency (ECHA) is also currently processing a proposal to restrict PFASs as a class under REACH (FPF reported).
The study highlights that a significant number of consumer products exceed regulatory PFAS thresholds after oxidation, showing that precursor testing is critical for compliance evaluation. Bleuler and co-authors conclude that their results “demonstrate the usefulness of a TOP assay for enforcing regulatory compliance.”
Reference
Bleuler, C. et al. (2026). “Beyond the watchlist: How the TOP assay exposes untargeted PFASs for current and future regulations in consumer products.” Chemosphere. DOI: 10.1016/j.chemosphere.2026.144841
