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PFOS, PFOA, PFNA and PFHxS are the PFAS substances that currently contribute most to human exposure, and in 2020 the European Food Safety Authority (EFSA) presented a draft opinion on a tolerable intake of 8 ng/kg/week for the sum of these four substances (equaling 0.42 μg/kg if expressed as an annual dose). Diet is usually the dominating exposure pathway, and in particular the intake of PFOS has been shown to be strongly related to the consumption of fish and seafood. Those who eat freshwater fish may be especially at risk since freshwater and its biota typically display higher PFOS concentrations than marine systems. In this study, we estimated the range in PFOS intake among average Swedish "normal" and "high" consumers of freshwater fish. By average we mean persons of average weight who eat average-sized portions. The "normal consumers" were assumed to eat freshwater fish 3 times per year, and the "high consumers" once a week. Under these assumptions, the yearly tolerable intake for "normal" and "high" consumers is reached when the PFOS concentrations in fish equals 59 and 3.4 μg per kg fish meat. For this study, PFOS concentrations in the muscle tissue of edible-sized perch, pike and pikeperch were retrieved from three different Swedish datasets, covering both rural and urban regions and a total of 78 different inland waters. Mean PFOS concentrations in fish from these sites varied from 0.3 to 750 μg/kg. From the available data, the annual min-max dietary PFOS intake for male "normal consumers" was found to be in the range 0.0021-5.4 μg/kg/yr for the evaluated scenarios, with median values of 0.02-0.16 μg/kg/yr. For male "high consumers", the total intake range was estimated to be 0.04-93 μg/kg/yr, with median values being 0.27-1.6 μg/kg/yr. For women, the exposure estimates were slightly lower, about 79% of the exposure in men. Despite highly variable PFOS concentrations in fish from different sites, we conclude that the three most commonly consumed freshwater species in Sweden constitute an important source for the total annual intake even for people who eat this kind of fish only a few times per year. The analyses of PFOA, PFNA and PFHxS showed values which were all below detection limit, and their contribution to the total PFAS intake via freshwater fish consumption is negligible in comparison to PFOS., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Non-invasive samples present ethical and practical benefits for investigating human exposure to hazardous contaminants, but analytical challenges and difficulties to interpret the results limit their application in biomonitoring. Here we investigated the potential for using hair, nail and urine samples as a measure of internal exposure to an array of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in two populations with different exposure conditions. Paired urine-serum measurements of PFASs from a group of highly exposed fishery employees displayed strong correlations for PFASs with three to eight perfluorinated carbons (ρ > 0.653; p < 0.01). Consistent statistical correlations and transfer ratios in nails and hair from both populations demonstrated that these non-invasive samples can be used as a measure of internal exposure to perfluorooctane sulfonic acid and C8 chlorinated polyfluoralkyl ether sulfonic acid (C8 Cl-PFESA). Contrastingly, the infrequent detections and/or lack of consistent transfer ratios for perfluorooctanoic acid, perfluorononanoic acid and short-chain PFASs in hair and nail samples indicate passive uptake from the external environment rather than uptake and internal distribution. Collectively, the study supports the use of urine samples as a valid measure of internal exposure for a range of short- and medium-chain PFASs, while the validity of nail and hair samples as a measure of internal exposure may vary for different PFASs and populations. The ubiquitous detection of C8 Cl-PFESA in all sample matrices from both populations indicates widespread exposure to this contaminant of emerging concern in China., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In recent exposure modeling studies diet has been identified as the dominant pathway of human exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). However, the paucity of highly sensitive and accurate analytical data to support these studies means that their conclusions are open to question. Here a novel matrix effect-free method is described for ultra-trace analysis of perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids in dietary samples of varied composition. The method employs ion pair extraction of the analytes into methyl tert-butyl ether and subsequent solid phase extraction clean-up on Florisil and graphitized carbon. The target compounds are separated and detected using ultra performance liquid chromatography coupled to tandem mass spectrometry. Special care was taken to avoid procedural blank contamination and potential contamination sources were elucidated. The performance of the method was validated for five different food test matrices including a duplicate diet sample. Method detection limits in the low to sub pgg(-1) range were obtained for all target analytes, which is 5-100 times more sensitive than previously reported for duplicate diet samples. Total method recoveries were consistently between 50 and 80% for all analytes in all tested food matrices and effects of co-extracted matrix constituents on ionization of the target compounds were found to be negligible. The precision of the method (defined as percentage relative standard deviation) at concentrations close to the respective method limits of quantification was <15% for all analytes. Accurate quantification at ultra-trace levels was demonstrated by laboratory control spike experiments. For the first time the presence of long-chain PFCAs in duplicate diet samples is reported. The method presented here can thus support an improved assessment of human exposure from dietary intake for a range of PFCA and PFSA homologues. Re-analysis of duplicate diet samples, which had been analyzed earlier using another analytical methodology, indicated that dietary intake of PFOA and PFOS may previously have been overestimated., (Copyright © 2012 Elsevier B.V. All rights reserved.)