Serum biomonitoring of per- and polyfluoroalkyl substances (PFASs) in the adult population of Switzerland: Results from the pilot phase of the Swiss health study

Monitoring human exposure to per- and polyfluoroalkyl substances (PFASs) is of significant public health relevance, given the documented associations between PFAS exposure and a range of adverse health outcomes. This study aimed to provide a sensitive and reliable analytical approach for the determination of PFASs in human serum and to advance the understanding of PFAS exposure. Serum samples from 630 adult participants from the population-based Swiss Health Study pilot phase were analysed for 30 legacy and emerging PFASs. Quantitative analysis was performed after specific sample preparation using high-performance liquid chromatography coupled to mass spectrometry. The association between PFAS serum concentrations and selected demographic and behavioural parameters of interest was assessed using linear regression. The developed method enabled sensitive high-throughput analysis and resulted in reliable validation parameters and robust quantification performance. The study revealed that, while the prevalence of emerging PFASs was observed to be marginal, legacy PFASs predominated. Perfluorooctane sulfonic acid (PFOS, geometric mean (GM) 6.6 ng/mL), perfluorooctanoic acid (PFOA, GM 1.3 ng/mL) and perfluorohexane sulfonic acid (PFHxS, GM 1.2 ng/mL) were detected in all serum samples and contributed 88 % to the median sum of determined PFASs (10.3 ng/mL). The levels of PFOA and PFOS were found to be associated with age and gender. Furthermore, PFOS levels were associated with consumption of fish, particularly freshwater species, while PFOA levels were negatively associated with the duration of breastfeeding. Regional disparities were also observed. Several results exceeded specific health thresholds for PFAS intake or human biomonitoring, but the observed values were overall comparable to similar studies conducted worldwide. The provision of comprehensive information on a wide range of legacy and emerging PFASs facilitates a more complete identification of possible sources of exposure, not only in the regions concerned, but also beyond, and establishes a robust foundation for the guidance of future investigations.