The CHARGE study: An assessment of parental occupational exposures and autism spectrum disorder

Objectives: The aim of this study is to determine if parental occupational exposure to 16 agents is associated with autism spectrum disorder (ASD). Methods: Demographic, health and parental occupational data were collected as part of the CHildhood Autism Risks from Genetics and Environment study. The workplace exposure assessment was conducted by two experienced industrial hygienists for the parents of 537 children with ASD and 414 typically developing (TD) children. For each job, frequency and intensity of 16 agents were assessed and both binary and semi-quantitative cumulative exposure variables were derived. Logistic regression models were used to calculate adjusted odds ratios (OR) and 95% confidence intervals (CI) to assess associations between parental occupational exposures 3 months pre-pregnancy until birth. Results: The OR of ASD in the children of mothers exposed to any solvents was 1.5 times higher than the mothers of TD children (95% CI=1.01-2.23). Cumulative exposure indicated that the OR associated with a moderate level of solvent exposure in mothers was 1.85 (95% CI=1.09, 3.15) for children with ASD compared with TD children. No other exposures were associated with ASD in mothers, fathers or the parents combined. Conclusion: Maternal occupational exposure to solvents may increase the risk for ASD. These results are consistent with a growing body of evidence indicating that environmental and occupational exposures may be associated with ASD. Future research should consider specific types of solvents, larger samples and/or different study designs to evaluate other exposures for potential associations with ASD.