Assessing the relation between plasma PCB concentrations and elevated autistic behaviours using Bayesian predictive odds ratios

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by impaired social communication and repetitive or stereotypic behaviours. In utero exposure to environmental chemicals, such as polychlorinated biphenyls (PCBs), may play a role in the etiology of ASD. We examined the relation between plasma PCB concentrations measured during pregnancy and autistic behaviours in children aged 3-4 years old in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. We calculated Bayesian predictive odds ratios for more autistic behaviours based on a latent variable model with a threshold of SRS >60. We found small and imprecise increases in the mean SRS score for the highest quartile of plasma PCB concentrations compared with the lowest quartile; these were accompanied by larger increases in the odds of more autistic behaviour. In conclusion, we found some evidence that plasma PCB concentrations during pregnancy may be associated with small increases in autistic behaviours in this cohort