Thimo Groffen

Per- and polyfluoroalkyl substances (PFASs) are widely used, with significant environmental and health impacts. PFASs often exist as isomers with distinct physicochemical properties that influence their environmental fate and toxicity. This study advances PFAS analysis through isomeric resolution of 41 linear and 39 branched congeners by liquid chromatography-ion mobility-high-resolution mass spectrometry (LC-IM-HRMS), reporting the largest collision cross-section (CCS) data set for PFAS structural isomers to date, including the first reported drift-tube ion mobility (DTIM)-derived DTCCSN2 values for PFNA and PFNS isomers. The workflow was successfully applied to 41 great and blue tit egg samples collected near a contaminated industrial site in Belgium, where 20 linear and 34 branched PFAS isomer features were detected. Correlation analysis between the number of isomers detected for each PFAS in bird eggs revealed distinct co-occurrence patterns among branched PFAS isomers, with PFBS and PFDoDA showing unique behavior compared with other PFAS classes. A significant difference in PFOS isomer profiles was identified between the two species, which may be related to differences in foraging behavior and species-specific accumulation. The results demonstrate that LC-IM-HRMS is a useful tool for confidence-enhanced PFAS isomer identification in complex biological samples despite the limited availability of single-branched isomer standards and highlight the value of isomer-resolved analysis for environmental biomonitoring and exposure characterization.

The extensive production and use of per- and polyfluoroalkyl substances (PFAS) over recent decades have resulted in their pervasive distribution in environmental compartments worldwide. PFAS concentrations in soil and biota near fluorochemical manufacturing facilities tend to be typically higher near hotspots, which suggests that the consumption of home-produced foods near such hotspots most likely results in higher human exposure. One prominent European hotspot is located near the 3M fluorochemical production facility in Zwijndrecht (Belgium), where the relative contributions of different exposure pathways remain insufficiently characterised. This study therefore aimed to assess the PFAS concentrations and compositional profiles in serum, dwellings and gardens of teenagers residing near this hotspot. Serum samples from teenagers, along with multiple environmental matrices (i.e., soil, compost, vegetables/fruits/nuts, chicken eggs, rainwater and indoor house dust) were analysed for 21 selected PFAS. Additionally, potential determinants of PFAS occurrence and distribution across matrices were investigated using detailed questionnaire data. We found perfluorooctane sulfonic acid (PFOS) to be the predominant compound in both soil and serum, while perfluorobutanoic acid (PFBA) was most dominant in rainwater, compost, house dust and pods. Perfluorobutane sulfonic acid (PFBS) was most abundant in fruits and chicken eggs, while perfluorododecanoic acid (PFDoDA) was predominant in rooting vegetables and nuts. N-methylperfluorooctane sulfonamidoacetic acid (MePFOSAA) was the dominant compound in fruiting, stem, and leafy vegetables. These results indicate differences in accumulation pathways among the different media and/or differences in affinities of different PFAS in the matrices. Additionally, several environmental and behavioural factors were identified as determinants for PFAS in soil, compost, tree fruits, fruiting vegetables, chicken eggs and house dust, providing insight into potential drivers of exposure variability. The most important factors were related to the soil characteristics, the composting of grass and weeds, the chicken feed (i.e., bread, commercial feed), the type and frequency of ventilation and the frequency of cleaning.

Per- and polyfluoroalkyl substances (PFAS) are global pollutants, yet data from tropical freshwater ecosystems remain scarce. This study provides the first assessment of PFAS occurrence in the Rusizi delta (Burundi), from tributaries to Lake Tanganyika, by analyzing water, sediment, macrophytes, and fish, and by evaluating human health risks from fish consumption. In water, only PFOA (<0.60–7.80 ng/L) was detected and showed a uniform spatial distribution. Sediment concentrations were largely below quantification limits, likely reflecting unfavorable sorption conditions. Macrophytes were dominated by short-chain PFAS, particularly PFBS, without consistent species- or site-specific patterns, supporting their potential as biomonitors of cumulative PFAS exposure. Fish exhibited the highest PFAS diversity, with more diverse profiles in liver than muscle, although tissue-specific patterns were often absent. PFBS was dominant across fish species, and emerging PFAS (e.g., PFBS and NaDONA) were frequently detected. Human health risks from fish consumption were, except for children, mostly below EFSA tolerable weekly intake values for regulated PFAS, but potential concern for adolescents and adults emerged when PFAS were expressed as PFOA equivalents. This study provides essential baseline data for tropical freshwater systems and highlights the need for expanded PFAS monitoring and risk assessment in data-poor regions.

Targeted analysis of per- and polyfluoroalkyl substances (PFAS) relies on a limited number of reference standards, and consequently, many PFAS remain unidentified, which restricts comprehensive monitoring and risk assessment. Here, we apply high-resolution mass spectrometry (HRMS)-based suspect and nontarget screening (SS/NTS), alongside targeted analysis, to detect and (semi)quantify legacy, emerging, and novel PFAS in soils near a PFAS hotspot in Flanders, Belgium. Targeted analysis quantified 36 PFAS, with perfluorooctanesulfonic acid (PFOS) as the most predominant, alongside precursors such as ethyl perfluorooctane sulfonamido acetic acid (Et-FOSAA) and perfluorooctane sulfonamide (FOSA). On the other hand, SS/NTS identified over 100 PFAS homologues and isomers, including pentafluorosulfide sulfonic acids (SF₅-PFSAs), perfluorophosphinic acids (PFPiAs), and perfluorophosphoric diesters (PFPDEs). Total PFAS concentrations at the 3M site varied widely, reaching 118.5 μg/g, among the highest reported globally. These findings highlight the complexity of PFAS contamination in the study area and the need for site-specific analyses to support monitoring, source tracking, regulation, and risk assessment.