Particulate matter exposure during pregnancy and infancy and risks of autism spectrum disorder in children: A systematic review and meta-analysis

Purpose: This meta-analysis aimed to clarify the relationship between particulate matter (PM) and autism spectrum disorder (ASD) in detail. Methods: A systematic literature search was performed using eight databases before April 9, 2022. The estimated effects were combined separately according to the PM type. Subgroup analyses were conducted in terms of the study design type, study location, exposure window, birth year, and sex. Results: PM2.5 was associated with an increased risk of ASD, while PM10 was not. PMc, PM1, and diesel particulate matter (DPM) were also associated with an increased risk of ASD. Specifically, a 10 mu g/m(3) increase in PM2.5 was associated with a 1.337-fold increased risk of ASD in children, and a 10 mu g/m(3) increase in PMc and PM1 may increase the risk of ASD by 1.062 and 3.643 times, respectively. PM2.5 exposure may increase the risk of ASD in boys. Exposure to PMc might increase the risk of ASD in children born after the year 2000. The combined results of different PM differed between studies with continuous and non-continuous data for different study design type, study location, and birth year. The sensitive window for PM2.5 exposure to increase the risk of ASD may be from the first, second, and third trimesters to the first year of the postnatal period. Exposure to PMc during pregnancy was significantly associated with ASD. Conclusion: Exposure to PM2.5 may increase the risk of ASD in boys. Exposure to PM2.5 during the first, second, and third trimesters and postnatally increased the risk of ASD.