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

Abstract

Background Charleston Harbor has elevated concentrations of PFAS in dolphins, but local human exposure data are limited. Objectives We sought to describe PFAS serum concentrations’ temporal trends among Gullah African American residents of coastal South Carolina. Methods Longitudinal 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. Results Population 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. Conclusions Many 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.

Serum concentrations of legacy and emerging per- and polyfluoroalkyl substances in the Anniston Community Health Surveys (ACHS I and ACHS II)

“…Our observed decreases in PFOS and PFOA were similar to other studies of similar timeframe ( Worley et al, 2017 ). Focusing on PFOS, another study of Gullah African Americans from coastal South Carolina showed that PFOS dropped approximately nine percent each year between 2003 and 2013 ( Gribble et al, 2015 ) which is consistent with our observations in residents of Anniston, Alabama. Finally, it is hard to interpret and compare our observations of possibly increased circulating levels of HFPO-DA over time because few studies in the United States focusing on matched serum samples have reported on HFPO-DA levels using analytical methodologies with comparable LODs.…”

Online Serum PFOA Calculator for Adults

“…Individuals may also differ in their capacity for bodily storage and excretion of PFOA. For example, there is some evidence of small effects of age and sex on PFOA retention ( Brede et al 2010 ; Zhang et al 2013 ; Gribble et al 2015 ), potentially affecting individual-specific values for the half-life and steady-state ratio. At present these effects are not very well characterized, but their potential impacts can be explored by modifying those parameters in the “Advanced options” section.…”

Tap Water Contributions to Plasma Concentrations of Poly- and Perfluoroalkyl Substances (PFAS) in a Nationwide Prospective Cohort of U.S. Women

“…Interindividual variability in consumption rates and toxicokinetics can affect the contribution of drinking water to serum PFAS concentrations. Uptake and elimination of PFAS varies depending on age, race, menstrual status, childbirth, and breastfeeding (Gribble et al. 2015; Wong et al.…”