Prenatal exposure to perfluoroalkyl substances and child intelligence quotient: Evidence from the Shanghai birth cohort

Background and aim: Epidemiological evidence on the association between prenatal exposure to Perfluoroalkyl substances (PFAS) and child cognition remains unclear. Thus, we aimed to investigate whether prenatal exposure to PFAS is associated with intelligence quotient (IQ) in offspring.

Method: This study population included 2031 mother-child pairs in the Shanghai Birth Cohort (SBC) enrolled during 2013-2016. Ten PFAS were measured by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS-MS) in maternal plasma samples collected in early gestation between 9 and 16 weeks of gestation. Child IQ was assessed using the Wechsler Preschool and Primary Scales of Intelligence-Fourth Edition (WPPSI-IV) at 4 years of age. Multivariable linear regression models were used to estimate the associations between individual PFAS concentrations (as a continuous variable or categorized into tertiles) and child IQ. A quantile g-computation approach was used to evaluate the joint and independent effects of PFAS on IQ. We also examined whether the associations varied by child sex.

Results: We found no significant associations between ln-transformed nine individual PFAS and child full scale IQ (FSIQ) or subscale IQ after adjusting for potential confounders. The observed associations were not modified by child sex. PFAS in tertiles showed the same pattern. Results from quantile g-computation showed that PFAS mixture was not associated with child IQ; perfluorobutane sulfonate was negatively associated with FSIQ (β, -0.81; 95 % CI: -1.55, -0.07), and perfluorooctane sulfonate was also associated with lower fluid reasoning index scores (β, -1.61; 95 % CI: -3.07, -0.16) while adjusting for the other PFAS.

Conclusion: PFAS mixture during early pregnancy was not associated with child IQ. For certain individual PFAS, there were inverse associations with FSIQ or subscale IQ. Considering the evidence is still inconsistent, further research is needed to confirm or refute these results in other populations and to elucidate the potential neurotoxicology of PFAS.