Per- and polyfluoroalkyl substances (PFAS) in serum of 2- to 5-year-old children: temporal trends, determinants, and correlations with maternal PFAS concentrations

Background/Aim: Early-life exposure to per- and polyfluoroalkyl substances (PFAS) occurs through placental and lactational transfers and ingestion of contaminated food, drinking water, and dust. However, little is known about temporal trends of PFAS in children’s serum, especially since the phase-out of certain long-chain PFAS in the early 2000s. We investigated temporal trends and determinants of child serum PFAS concentrations and assessed their correlations with maternal PFAS concentrations. Methods: We included 551 children age 2 to 5 years from the CHildhood Autism Risks from Genetics and Environment (CHARGE) study. We quantified 14 PFAS in their serum samples collected during 2009-2017. For 9 PFAS detected in greater than 74% of the samples, we performed multiple regression with adjustment of potential determinants to calculate least square geometric means of PFAS concentrations for each sampling year and to estimate their average annual percent changes. For a subset of 354 children, we quantified 9 PFAS in their mother’s serum collected at the same study visit and computed Spearman’s correlation coefficients between maternal and child PFAS concentrations. Results: During the study period, child serum concentrations of 9 PFAS significantly decreased (range of annual percent changes: 6-12%). Child PFAS concentrations were positively associated with longer breastfeeding duration. Non-Hispanic white children had higher PFAS concentrations compared to Black, Asian, and multiracial children. For 354 mother-child pairs, the correlation coefficients between maternal and child PFAS concentrations ranged from 0.15 to 0.36, depending on the compound. Conclusions: Our results showed that childhood body burdens of PFAS decreased from 2009 to 2017. Breastfeeding appears to contribute to higher child PFAS concentrations and lower maternal PFAS concentrations, resulting in relatively low correlation coefficients between maternal and child PFAS concentrations for samples collected in early childhood. Keywords: PFAS, child serum, temporal trends, determinants, breastfeeding