Association between Prenatal and Early Childhood Exposure to Ambient Particulate Matters and Risks of Autism Spectrum Disorder: An Exposure-Response Meta-analysis

OPS 53: Air pollution and neurological outcomes, Room 217, Floor 2, August 27, 2019, 10:30 AM - 12:00 PM Background: Complex genetic and environmental interactions could contribute to the development of autism spectrum disorder (ASD). The association between particulate matter (PM) exposure and risks of ASD in children remained controversial. The National Ambient Air Quality Standards (NAAQS) for PM2.5 are intended to protect health of sensitive populations. Methods: We searched PubMed, Embase, Cochrane, Web of Science, Compendex, Biosis Previews, and Agricultural & Environmental Science Databases for studies published before February 2019, investigating the association between prenatal and postnatal PM2.5 exposure and risks of ASD in children. Primary analysis focused on risks of ASD during different exposure windows (1st, 2nd, 3rd trimesters, and early childhood period). Exposure-response meta-regression was performed to summarize pooled risks of ASD across various background PM2.5 levels. Results: We identified 11 studies (2 cohort and 9 case-control studies), including 311,789 children, eligible for this meta-analysis. Exposure to PM2.5 with per 10 μg/m3 increment at the 3rd trimester and early childhood period was associated with increased risks of ASD by 35% (relative risk, RR = 1.35, 95% C.I. = 1.18 – 1.55) and 64% (RR = 1.64, 95% C.I. = 1.16 – 2.34), respectively, but not significant at the 1st and 2nd trimesters. The effects of PM2.5 exposure with per 10 μg/m3 increment increased in an exposure-response manner, from 30% (RR = 1.30, 95% C.I. = 1.02 – 1.66) to 77% (RR = 1.77, 95% C.I. = 1.21 – 2.61) at background PM2.5 levels from 8 μg/m3 to 42 μg/m3, respectively. Conclusions: Our findings suggested the association between PM2.5 exposure and risks of ASD, particularly within specific exposure windows. The risks of ASD could occur at broad PM2.5 levels, even lower than current NAAQS for PM2.5.