New research suggests children with autism spectrum disorder (ASD) are more likely to have been exposed to airborne toxins during the first two months of their mothers' pregnancies.

ASD is a significant public health issue that has increased in prevalence over the years, the University of Pittsburgh School of the Health Sciences reported.

"Despite its serious social impact, the causes of autism are poorly understood. Very few studies of autism have included environmental exposures while taking into account other personal and behavioral risk factors. Our analysis is an addition to the small but growing body of research that considers air toxics as one of the risk factors for ASD," said Dr. Evelyn Talbott, principal investigator of the analysis and professor of epidemiology at Pitt Public Health.

To make their findings, researchers performed a population-based study of families with and without ASD living in six southwestern Pennsylvania counties. They noticed higher levels of exposure to chromium and styrene in children with ASD.

"This study brings us a step closer toward understanding why autism affects so many families in the Pittsburgh region and nationwide - and reinforces in sobering detail that air quality matters," said Grant Oliphant, president of The Heinz Endowments. "Our aspirations for truly becoming the most livable city cannot be realized if our children's health is threatened by dangerous levels of air toxics. Addressing this issue must remain one of our region's top priorities."

The study encompassed 217 families of children with ASD and two control groups, which is what gives the findings its strength. The team used the National Air Toxics Assessment (NATA) to estimate exposure to 30 pollutants known to cause endocrine disruption or neurodevelopmental issues in the participants. They found the children with the highest rates of exposure to styrene and chromium had a 1.4 to two-fold greater risk of ASD.

"Our results add to the growing body of evidence linking environmental exposures, such as air pollution, to ASD," Talbott said. "The next step will be confirming our findings with studies that measure the specific exposure to air pollutants at an individual level to verify these EPA-modeled estimates."

The findings were presented at the American Association for Aerosol Research annual meeting.