Exposure and Blood–Cerebrospinal Fluid Barrier Permeability of PFASs in Neonates

The blood–cerebrospinal fluid barrier (BCSFB) is essential for protecting neonates from potential cerebral damage and neurological disorders caused by per- and polyfluoroalkyl substances (PFASs). However, the occurrence of various PFASs in neonatal cerebrospinal fluid (CSF) and matched serum as well as the penetration of PFASs across the BCSFB in the developing brain remain unclear. This study investigated 32 PFASs, including homologues, isomers, alternatives, and precursors, in neonatal CSF and serum collected from Hangzhou, China. Total-PFOA was the dominant PFAS in both matrixes, occupying 64% in neonatal serum (median: 10.4 ng/mL) and 78% in neonatal CSF (median: 0.24 ng/mL), followed by total-PFOS and 6:2 Cl-PFESA in serum. Many isomers of PFOA, PFOS, and PFHxS were frequently detected in neonatal serum, but only linear isomers were relatively frequently detected in neonatal CSF. The median ratios of PFAS concentrations in CSF to those in paired serum (R CSF/Serum) of neonates were 0.0308 for total-PFOA, 0.0157 for total-PFOS, and 0.0277 for 6:2 Cl-PFESA, which were all higher than those of adults reported in previous studies. The ln-transformed 6:2 Cl-PFESA level in CSF showed significant negative associations with the neonatal head circumference. This study provides novel and valuable information about neonatal PFAS exposure and developing BCSFB.