Associations between brake and tire wear-related PM metal components, particulate oxidative stress potential, and autism spectrum disorder in Southern California.

BACKGROUND

Air pollution is a global health concern, with fine particulate matter (PM) constituents posing potential risks to human health, including children's neurodevelopment. Here we investigated associations between exposure during pregnancy and infancy to specific traffic-related PM components with Autism Spectrum Disorder (ASD) diagnosis.

METHODS

For exposure assessment, we estimated PM components related to traffic exposure (Barium [Ba] as a marker of brake dust and Zinc [Zn] as a tire wear marker, Black Carbon [BC]) and oxidative stress potential (OSP) markers (Hydroxyl Radical [OP] formation, Dithiothreitol activity [OP], reactive oxygen species [ROS]) modeled with land use regression with co-kriging based on an intensive air monitoring campaign. We assigned exposures to a cohort of 444,651 children born in Southern California between 2016 and 2019, among whom 11,466 ASD cases were diagnosed between 2018 and 2022, Odds ratios (ORs) and 95% confidence intervals (CIs) were obtained with logistic regression for single pollutant and PM mass co-adjusted models, also adjusting for sociodemographic characteristics.

RESULTS

Among PM components, we found the strongest positive association with ASD for our brake wear marker Ba (OR = 1.29, 95 % CI: 1.24, 1.34). This was followed by an increased risk for all PM oxidative stress potential markers; the strongest association was with ROS formation (OR = 1.22, 95 % CI: 1.18, 1.25). PM mass was linked to ASD in Hispanic and Black children, but not White children, while traffic-related PM and OSP markers increased ASD risk across all groups. In neighborhoods with the lowest socioeconomic status (SES), associations with ASD were stronger for all examined pollutants compared to higher SES areas.

CONCLUSIONS

Our findings suggest that brake wear-related PM and PM OSP are associated with ASD diagnosis in Southern California. These results suggest that strategies aimed at reducing the public health impacts of PM need to consider specific sources.