Shifting Global Exposures to Poly- and Perfluoroalkyl Substances (PFASs) Evident in Longitudinal Birth Cohorts from a Seafood-Consuming Population

Abstract

Rapid declines in legacy poly- and perfluoroalkyl substances (PFASs) have been reported in human populations globally following changes in production since 2000. However, changes in exposure sources are not well understood. Here, we report serum concentrations of 19 PFASs (∑₁₉PFAS) measured in children between 1993 and 2012 from a North Atlantic fishing community (Faroe Islands). Median ∑₁₉PFAS concentrations in children (ages 5-13 years) peaked in 2000 (47.7 ng mL^-1) and declined significantly by 14.4% year^-1 until 2012. Principal component analysis (PCA) identified two groups of PFASs that likely reflect exposures from diverse consumer products and a third group that consisted of perfluorocarboxylic acids (PFCAs) with nine or more carbons (C ≥ 9). These C ≥ 9 PFASs are strongly associated with mercury in children's hair, a well-established proxy for seafood consumption, especially perfluoroundecanoic acid (PFUnDA, r = 0.72). Toxicokinetic modeling shows PFAS exposures from seafood have become increasingly important (53% of perfluorooctanesulfonate, PFOS, in 2012), despite a decline in whale consumption in recent years. We infer that even in a major seafood-consuming population, declines in legacy PFAS exposure after 2000 were achieved by the rapid phase out of PFOS and its precursors in consumer products. These results emphasize the importance of better understanding exposures to replacement PFASs in these sources.

Figure 1.

Schematic of measurements and data synthesized in this study. *POSF: Perfluorooctanesulfonyl fluoride, the parent compound to PFOS and its precursors. PFOA: perfluorooctanoic acid.

Figure 2.

Panel (A) shows the average composition of 19 PFASs measured in Faroese children’s serum over time. Panel (B) shows individual observations for each child as colored connected dots and population medians as black connected dots for nine select PFASs.

Figure 3.

Results from Principal Component Analysis (PCA) on measured PFASs in serum from Faroese children between 1993 and 2013. Panel (A) shows the loadings for each principal component with dominant loadings shaded. Panel (B) shows the first and third components of each data point plotted against each other and colored by year. The dominant compounds for each component are shown as vectors with magnitudes relative to a unit circle.

Figure 4.

Results from principal component analysis (PCA) on measured PFASs in serum from Faroese children between 1993 and 2013. Panel (A) shows the first and third components of each data point plotted against each other and colored by whether or not a child identified as eating pilot whale meat. The dominant compounds for each component are shown as vectors with magnitudes relative to a unit circle. Panel (B) shows the correlation coefficient, r, between hair Hg and PFUnDA in children who do and do not eat whale meat. The solid line represents the line of best fit and the shaded region represents the 95% confidence interval.

Figure 5.

Inputs and results of toxicokinetic modeling used to reconstruct seafood consumption magnitudes in Faroese children and PFOS and PFNA exposures. Panel (A) shows measured concentrations of mercury (Hg) in children’s hair over time. Panel (B) shows modeled whale consumption rates calculated from toxicokinetic modeling for Hg. Panels (C) and (D) shows modeled serum PFOS and PFNA concentrations. Panels (E) and (F) show modeled contributions of pilot whale consumption to total PFOS and PFNA measured in serum.