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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.

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Perfluoroalkane substances (PFAS) comprise a large family of chemicals of environmental concern and are subject to chemical analyses, international regulation, and risk assessments. Environmental samples including air, water, sediment, and soil as abiotic matrices, food samples comprising fish, meat (beef, sheep, chicken), egg, butter, and milk as well as human milk samples were assessed using uni- and multivariate methods. Participating countries were asked to provide baseline samples and not target potential hotspots. Chemometric analysis was possible for only three of the 15 PFAS monitored, namely perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS). The assessments showed that PFAS contamination in developing countries and in all matrices considered was almost equally attributed to PFOS and PFOA; PFHxS did not play a role. Subsequently, across all samples, PFOS and PFOA were strongly negatively correlated (spearman correlation coefficient r = −0.94). The measured values showed moderate positive correlation between PFOS and PFOA (r = 0.76) indicating common sources or environmental behavior. No clear pattern could be observed for geographic locations nor for transfers between matrices. Whereas the abiotic samples—soil, sediment, air—gave a very heterogenous picture (very small p-values) and had wide ranges and outliers, the measured values of the biota samples were not significantly different between matrices.