Prenatal exposure to per- and polyfluoroalkyl substances in association with autism spectrum disorder in the MARBLES study

Background: Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) has shown potential to adversely affect child brain development, but epidemiologic evidence remains inconsistent. We examined whether prenatal exposure to PFAS was associated with increased risk of autism spectrum disorder (ASD). Methods: Participants were 173 mother–child pairs from MARBLES (Markers of Autism Risk in Babies – Learning Early Signs), a high-risk ASD cohort. At 3 years old, children were clinically confirmed for ASD and classified into ASD (n = 57) and typical development (TD, n = 116). We quantified nine PFAS in maternal serum collected during pregnancy. We examined associations of ASD with individual PFAS as well as the combined effect of PFAS on ASD using scores of the first principal component (PC-1) accounting for the largest variance. Results: Prenatal perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) showed positive associations (per 2 nanogram per milliliter increase: relative risk (RR) = 1.20, 95% CI: 0.90, 1.61 [PFOA]; RR = 1.24, 95% CI: 0.91, 1.69 [PFNA]), while perfluorohexane sulfonate (PFHxS) showed a negative association (RR = 0.88, 95% CI: 0.77, 1.01) with ASD risk. When examining associations of ASD with untransformed PFAS concentrations, PFOA, PFNA, and PC-1 were associated with increased ASD risk (per nanogram per milliliter increase: RR = 1.31, 95% CI: 1.04, 1.65; RR = 1.79, 95% CI: 1.13, 2.85; RR = 1.10, 95% CI: 0.97, 1.25, respectively), while the RR of PFHxS moved toward the null. Conclusions: From this high-risk ASD cohort, we observed increased risk of ASD in children exposed to PFOA and PFNA. Further studies should be conducted in the general population because this population may have a larger fraction of cases resulting from genetic sources.