Associations of cord blood concentrations of perfluoroalkyl substances with autistic traits in Singaporean children: The growing up in Singapore towards healthy outcomes study.

Background: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by social deficits and repetitive behaviors. Environmental pollutants may contribute to the etiology of ASD, but studies of perfluoroalkyl substances (PFAS) have shown conflicting results.

Objectives: We assessed associations between cord blood concentrations of PFAS with autistic traits at age seven years in a Singaporean birth cohort.

Methods: We measured cord blood concentrations of eight PFAS in a sample of 430 mother-child pairs from the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) cohort. We assessed autistic traits using the Social Responsiveness Scale Second Edition (SRS-2) and its sub-scores, in which higher scores indicate more autistic traits. We estimated covariate-adjusted associations between the PFAS and SRS-2 scores using Bayesian weighted quantile sum (BWQS) regression models for the PFAS mixtures and multivariable regressions for single PFAS. We additionally evaluated effect modification by biological sex.

Results: We observed a positive association between the PFAS mixture and SRS-2 cognition sub-scores (β per SD increase = 1.25 points, 95% CI -0.03, 2.40). Perfluorononanoic acid (PFNA) was the strongest contributor to the mixture effect. In single PFAS models, exposure to PFNA was associated with a higher SRS-2 total score (β = 0.93 points, 95% CI 0.29, 1.58), cognition sub-score (β = 1.26 points, 95% CI 0.55, 1.97), communication sub-score (β = 0.88 points, 95% CI 0.20, 1.56), and restrictive and repetitive behaviors sub-score (β = 0.93 points, 95% CI 0.23, 1.63). We also observed evidence of effect modification by sex for perfluoroundecanoic acid (PFUnDA) for the total score (p-effect modification [EM] = 0.03), cognition sub-score (p-EM = 0.03), and communication sub-score (p-EM = 0.04), with negative associations seen in females and null associations in males.

Discussion: Cord blood PFAS concentrations were positively associated with autistic traits measured by SRS-2.