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Within the global monitoring plan (GMP) established by article 16 of the Stockholm Convention on Persistent Organic Pollutants, perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) are recommended for analysis in core matrices to assess occurrence and changes geographically and with time. In 101 samples consisting of 86 national pools and 15 pools from States in Brazil obtained between 2008 and 2019, PFHxS was detected in 17% of the national pools and none in Brazil. PFOA and PFOS had a detection frequency of 100% and 92%, respectively. Other perfluoroalkane substances (PFAS) had either low detection frequencies and median values of zero (carboxylic acids C4–C11; except PFOA) or could not be quantified in any sample (sulfonic acids, C4–C10, and long-chain carboxylic acids, C12–C14). Correlation between PFOA and PFOS was moderately (r = 0.58). Whereas median values were almost identical (18.9 pg/g f.w. for PFOS; 18.6 pg/g f.w. for PFOA), PFOS showed larger ranges (< 6.2 pg/g f.w.−212 pg/g f.w.) than PFOA (< 6.2 pg/g f.w.−63.4 pg/g f.w.). It was shown that wealthier countries had higher PFOA concentrations than poorer countries. No difference in concentrations was found for samples collected in countries having or not having ratified the Stockholm Convention amendments to list PFOS or PFOA. The goal to achieve 50% decrease in concentrations within ten years was met by Antigua and Barbuda, Kenya, and Nigeria for PFOS and by Antigua and Barbuda for PFOA. In a few cases, increases were observed; one country for PFOS, four countries for PFOA.

To support the global monitoring plan on persistent organic pollutants (GMP) under the Stockholm Convention, 41 countries have exposed passive air samplers equipped with polyurethane foam disks (PUFs) to monitor perfluoroalkane substances (PFAS). The recommended procedure had PUFs exposed for three months during two years; analysis was performed in one expert laboratory to generate harmonized results. Chemical analysis using Soxhlet extraction with methanol or a 60:40 MTBE:methanol mixture, solid-phase extraction and UPLC/MSMS detection posed challenges as to matrix interference and sensitivity. Single PUFs as quarterly samples and combination of up to 4 PUFs as annual samples were analyzed; all concentrations were normalized to one PUF and 3 months exposure. Exceptionally high values (up to 36 000 pg SPFOS/PUF) were observed in nine samples from Zambia where a local source was identified. For the remaining 308 PUFs, PFOA had a higher median value (188 pg/PUF) than SPFOS (125 pg/PUF) whereas the mean value of SPFOS (254 pg/PUF) was slightly higher than the mean value for PFOA (230 pg/PUF). PFHxS concentrations were much lower in concentration and detection frequency and FOSA, as the only relevant PFOS precursor compound, showed a median value of zero. No clear regional differentiation was found.

To comprise the future requirements to detect low levels of perfluoroalkyl acids (PFAAs) including branched and linear perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) in food items, analytical methods for their determination in five different food matrices (cow milk, butter, chicken meat, beef, and fish) were developed and validated. Analytical method for eggs was only validated for PFOS and PFOA because of interfering substance appeared in some samples. The method applied on foods of animal origin includes alkaline digestion, extraction, and clean-up with solid phase extraction and adsorption on granular carbon where necessary. The method was shown effective to eliminate taurodeoxycholic acid (TDC), a bile acid that is an endogenous interference compound in egg samples causing ionization suppression and false positive result for PFOS when 499 > 80 transition was used for quantification. The validation was performed and resulted in recoveries >70% for all three PFAAs, the limits of quantification (LOQs) in all matrices were 3.1 pg g−1, 3.4 pg g−1, and 4.9 pg g−1 for PFHxS, PFOA, and L-PFOS, respectively. The optimized method was successfully applied to 53 food samples from the Swedish market and from developing countries. PFOS and PFOA were detected in all samples. PFHxS was detected in 76% of the samples. Further method development on separating interfering substance from PFHxS in egg is warranted due to relatively high detection of this compound in other food items. With this method, concentrations in the low pg g−1 range in food samples of animal origin were quantified including the branched PFOS isomers. This method can be applied to enforce potential future limit values for PFOS and PFOA as a consequence of the recent European Food Safety Authority (EFSA) recommendation where the tolerable intakes have been drastically lowered. Further method development is needed for foods of plant origin such as vegetables, flour, nuts, or bread.

The human milk monitoring component of the global monitoring plan under the Stockholm Convention on Persistent Organic Pollutants was implemented from 2016 to 2019 and had 44 human milk samples from primiparae collected in 42 countries and analyzed for perfluoroalkane substances (PFAS), at the MTM Research Centre at Örebro University, Sweden. The targeted compounds were restricted to the two listed PFAS (perfluorooctane sulfonic acid, PFOS and perfluorooctane carboxylic acid, PFOA) and the one recommended PFAS (perfluorohexane sulfonic acid, PFHxS). PFOA was quantified in all 44 samples in a quite narrow range (6.20 pg/g-37.4 pg/g); PFHxS was quantifiable in only four samples (max. 111 pg/g), and PFOS in 36 samples across a wide range (6.2 pg/g-212 pg/g). Branched PFOS isomers on average had a share of 16% of the total PFOS with a maximum of 33%. PFOS was highly correlated with PFHxS (Pearson correlation coefficient R = 0.95) and weakly but still positively with PFOA (R = 0.44). Statistical analysis (all on p0.05) showed that PFOS and PFOA in European countries were significantly different from those in African and Latin American countries and between high-income and low-income countries. PFOA tends to have higher concentrations in wealthier countries. No correlation was found for population density.