Traffic-related air pollution, particulate matter, and autism.

TLDR: Exposure to traffic-related air pollution, nitrogen dioxide, PM2.5, and PM10 during pregnancy and during the first year of life was associated with autism.

Abstract: Context: Autism is a heterogeneous disorder with geneticandenvironmentalfactorslikelycontributingtoits origins. Examination of hazardous pollutants has suggested the importance of air toxics in the etiology of autism,yetlittleresearchhasexamineditsassociationwith local levels of air pollution using residence-specific exposure assignments. Objective:To examine the relationship between trafficrelated air pollution, air quality, and autism. Design: This population-based case-control study includes data obtained from children with autism and control children with typical development who were enrolled in the Childhood Autism Risks from Genetics and the Environment study in California. The mother’s addressfromthebirthcertificateandaddressesreportedfrom a residential history questionnaire were used to estimate exposure for each trimester of pregnancy and first year of life. Traffic-related air pollution was assigned to each locationusingaline-sourceair-qualitydispersionmodel.Regional air pollutant measures were based on the Environmental Protection Agency’s Air Quality System data. Logisticregressionmodelscomparedestimatedandmeasuredpollutantlevelsforchildrenwithautismandforcontrol children with typical development. Setting: Case-control study from California. Participants: A total of 279 children with autism and a total of 245 control children with typical development. Main Outcome Measures: Crude and multivariable adjusted odds ratios (AORs) for autism. Results: Children with autism were more likely to live at residences that had the highest quartile of exposure totraffic-relatedairpollution,duringgestation(AOR,1.98 [95%CI,1.20-3.31])andduringthefirstyearoflife(AOR, 3.10 [95% CI, 1.76-5.57]), compared with control children.Regionalexposuremeasuresofnitrogendioxideand particulate matter less than 2.5 and 10 m in diameter (PM2.5 and PM10) were also associated with autism during gestation (exposure to nitrogen dioxide: AOR, 1.81 [95% CI, 1.37-3.09]; exposure to PM2.5: AOR, 2.08 [95% CI, 1.93-2.25]; exposure to PM10: AOR, 2.17 [95% CI, 1.49-3.16) and during the first year of life (exposure to nitrogen dioxide: AOR, 2.06 [95% CI, 1.37-3.09]; exposure to PM2.5: AOR, 2.12 [95% CI, 1.45-3.10]; exposure to PM10: AOR, 2.14 [95% CI, 1.46-3.12]). All regional pollutant estimates were scaled to twice the standard deviation of the distribution for all pregnancy estimates. Conclusions: Exposure to traffic-related air pollution, nitrogen dioxide, PM2.5,andPM10during pregnancy and during the first year of life was associated with autism. Further epidemiological and toxicological examinations of likely biological pathways will help determine whether these associations are causal.