Isomer-Specific Transplacental Efficiencies of Perfluoroalkyl Substances in Human Whole Blood

Data on isomer-specific transplacental transfer of perfluoroalkyl substances (PFASs) are very scarce. This study investigates transplacental transfer of 23 PFASs, including isomers of perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), by analyzing 63 paired maternal and cord whole blood samples collected in Hubei, China. Significant correlations (r = 0.311–0.888; p ≤ 0.013) were observed between the concentrations in maternal and cord blood for most PFASs, indicating that PFASs could be efficiently transported from mother to fetus. For perfluorocarboxylates, a U-shaped trend of transplacental transfer efficiencies (TTEs) with increasing carbon chain lengths was confirmed. For PFOA and PFOS branched isomers, TTEs generally increased as the branching point moved closer to the carboxyl or sulfonate moiety, and branched isomers transferred more efficiently than their linear isomers did. This is the first report of the TTEs of PFAS isomers based on human whole blood samples and the first calculation of the TTEs of perfluorooctane sulfonamide. For almost all PFASs, the TTEs we reported are lower than those from previous studies based on serum or plasma. Whole blood is recommended for risk assessment of PFAS placental transfer considering that PFASs exhibit different partitioning behaviors between blood matrices. More accurate parameters for the health risks of PFASs during prenatal exposure are provided here.