(HealthDay News) – Perinatal exposure to air pollutants is associated with increased odds of autism spectrum disorder (ASD), with stronger correlations seen for boys than girls, according to a study published online June 18 in Environmental Health Perspectives.

Andrea L. Roberts, PhD, from the Harvard School of Public Health in Boston, and colleagues examined the correlation between perinatal exposure to air pollutants, identified as being associated with ASD in previous research, and ASD using data from participants in the Nurses’ Health Study II, including 325 cases and 22,101 controls. The levels of hazardous air pollutants at the time and place of birth were modeled using data from the U.S. Environmental Protection Agency.

The researchers identified significant correlations for the highest vs. the lowest quintile of diesel, lead, manganese, mercury, methylene chloride, and an overall measure of metals with ASD, with odds ratios ranging from 1.5 for a measure of overall metals to 2 for diesel and mercury. For these exposures, linear trends were positive and statistically significant. The associations were stronger for boys than girls for most pollutants, and varied significantly according to sex.

“Perinatal exposure to air pollutants may increase risk for ASD,” the authors write. “Additionally, future studies should consider sex-specific biological pathways connecting perinatal exposure to pollutants with ASD.”

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