Quantitative Associations of Per- and Polyfluoroalkyl Substances in Segmented Hair with Serum and Dust: Potential of Hair as a Retrospective Biomarker

Human hair is a promising noninvasive biomonitoring matrix; however, its utility for retrospectively predicting exposure to per- and polyfluoroalkyl substances (PFAS) is not well understood, especially regarding quantitative associations and temporal mapping between hair with internal and external exposure. In this panel study, 24 females in South China were followed over 2 years, during which 131 hair samples (segmented into 1-4, 5-8, and 9-12 cm sections), 131 serum samples, and 122 dust samples were collected. Thirty-one PFAS congeners were analyzed, and PFAS exposure profiles differed across matrices. Significant positive dose-response relationships were observed for long-chain perfluorosulfonic acids (PFSAs) between hair and serum. Specifically, each unit increase in PFSAs concentrations in the three hair segments was associated with 74 (95% CI: 36.6-121.5), 14.9 (95% CI: 4.3-26.6), and 11.5% (95% CI: 3.1-20.6) higher average serum PFSAs concentrations corresponding to 1-3, 4-6, and 7-9 months prior to sampling, respectively. Proximal hair segments of perfluorooctanesulfonic acid (PFOS) and its alternative (6:2 Cl-PFESA) also showed significant associations, with respective increases of 28.7 and 11.7%. These findings confirm the complementarity of hair to serum and highlight its value for retrospectively characterizing serum concentrations of long-chain PFSAs.