Quantitative Evaluation of Perfluorooctanesulfonate (PFOS) and Other Fluorochemicals in the Serum of Children

Abstract

Perfluorooctanesulfonyl fluoride (POSF)–based materials include surfactants, paper and packaging treatments, and surface (e.g., carpet, upholstery, textile) protectants. A metabolite, perfluorooctanesulfonate (PFOS, C8F17SO3−), has been identified in the serum and liver tissue of nonoccupationally exposed adults and wildlife. Results from several repeat-dose toxicological studies consistently demonstrate that the liver is the primary target organ with an apparent threshold for the toxic effects of PFOS that can be expressed in terms of cumulative dose or body burden. The purpose of this study was to characterize the distribution of PFOS and six other fluorochemicals in 598 serum samples obtained from a multi-center study of children (ages 2–12) diagnosed with group A streptococcal infections. Using high-pressure liquid chromatography tandem mass spectrometry methods, serum PFOS concentrations ranged from 6.7 ppb (ng/mL) to 515 ppb (geometric mean 37.5 ppb, 95% CI 36.0–39.1) with an estimate of the 95th percentile (i.e., upper tolerance limit) of 89 ppb (upper 95% confidence limit 97 ppb). Serum perfluorooctanoate (PFOA) concentrations were approximately an order of magnitude lower than PFOS. Unlike comparable adult data reported elsewhere for PFOS and PFOA, children had substantially higher estimates for the 95th percentile for perfluorohexanesulfonate (65 ppb) and N-methyl perfluorooctanesulfonamidoacetate (12 ppb) (upper 95% confidence limits of 81 ppb and 15 ppb, respectively). The reasons for these dissimilarities in a subgroup of children remain to be determined. Different exposure and activity patterns between children and adults should be considered.