Transplacental Transfer Efficiency and Blood Partitioning of Perfluoroalkyl Substances

Abstract

Background: Recent studies have established the ability of perfluoroalkyl substances (PFASs) to pass through the placenta, however data on PFAS transfer efficiency and blood partitioning are limited.Aim: We evaluated transplacental transfer and blood partitioning of 16 PFASs detected in maternal serum, cord serum and cord whole blood, as well as the associations of mother-newborn characteristics with PFAS transfer efficiency and blood partitioning.Methods: We examined 151 mother-child pairs from two Faroese cohorts born in 1999-2001 and 2008-2009. Cord:maternal serum (transplacental transfer ratio [TTR]) and cord serum:whole blood (blood partitioning) ratio were estimated for 9 perfluorocarboxylates, 4 perfluorosulfonates and 3 precursor compounds. Multivariable regression analyses assessed the associations of potential predictors (i.e., cohort, maternal age, parity, gestational diabetes, sex and birthweight) with the ratios.Results: Correlations between maternal and cord serum concentrations were moderate to high for all PFASs (ρ: 0.41 to 0.95), indicating significant transfer from mother to fetus. Median TTRs ranged from 0.36 (PFDA and PFUnDA) to less than 1 for all PFASs, except FOSA (TTR: 1.21). All PFASs had higher concentrations in serum than whole blood, except FOSA and PFHpA, with partitioning ratios from 0.36 (FOSA) to 2.75 (PFUnDA). PFAS family and carbon chain length were important predictors of transfer and blood partitioning ratios, with U-shaped relationships seen between TTRs and carbon chain length. We also found significantly higher transplacental transfer to newborns of mothers diagnosed for gestational diabetes (adjusted ratio increases between 23% and 44% depending on PFAS).Conclusions: This study suggests that transplacental transfer and blood partitioning depends on PFAS family, carbon chain length and mother-newborn characteristics, such as gestational diabetes. These findings can improve PFAS exposure risk assessment in epidemiologic studies.