Longitudinal measures of perfluoroalkyl substances (PFAS) in serum of Gullah African Americans in South Carolina: 2003–2013

• Many PFAS decreased in serum of Gullah African Americans from Charleston, SC over the years 2003–2013.
• There was possible heterogeneity in individual serum PFAS trajectories by participant age.
• Additional more research is needed into PFAS routes of exposure and explanations for apparent temporal patterns of serum perfluoronated chemicals in these communities.

BackgroundCharleston Harbor has elevated concentrations of PFAS in dolphins, but local human exposure data are limited.ObjectivesWe sought to describe PFAS serum concentrations’ temporal trends among Gullah African American residents of coastal South Carolina.MethodsLongitudinal measures of PFAS in blood serum from a Gullah clinical sample, without lupus, were examined using spaghetti plots and visit-to-visit change scores (e.g., differences in concentrations between visits) among the 68 participants with repeated measures available. We also modeled population-level trends among the 71 participants with any data using proportionate percentile models, accounting for clustering through robust standard errors. In a post-hoc analysis we examined heterogeneity of temporal trends by age through mixed-effects models for the log-transformed PFAS compounds.ResultsPopulation concentrations of PFOS dropped approximately 9 (95% CI: 8, 10) percent each year over 2003–2013. This was concordant with individual PFOS trajectories (median PFOS change score −21.7 ng/g wet weight, interquartile range of PFOS change scores: −32.8, −14.9) and reports for other populations over this time period. Several other compounds including PFOA, PFHxS, and PFuNDA also showed a population-level decrease. However, examination of individual trajectories suggested substantial heterogeneity. Post-hoc analyses indicated that PFAS trajectories were heterogeneous by age.ConclusionsMany PFAS compounds are decreasing in a sample of Gullah African Americans from coastal South Carolina. There may be age differences in the elimination kinetics of PFASs. The possible role of age as a modifier of PFAS serum trends merits further research.