In a new study, researchers at the University of Pittsburgh found children with autism were more likely to have been exposed to certain air toxics during their mother's pregnancy and during the their first two years of life.
The paper's preliminary results have been accepted for review by the the American Association for Aerosol Research; it's one of the first times researchers have found a correlation between air pollution and autism rates.
Scientists located the link after interviewing the families of more than 200 children diagnosed with autism. The results, including survey questions about air quality and exposure, were then compared to the responses from two separate control groups -- each including families without a child on the autism spectrum.
"Autism spectrum disorders are a major public health problem, and their prevalence has increased dramatically," the study's lead researcher Dr. Evelyn Talbott said in a press release. "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."
The study focused on children living in six southwestern counties of Pennsylvania. Interview answers were augmented with local data from the EPA's National Air Toxics Assessment, including location-specific exposure estimates for 30 pollutants known to be linked to endocrine system disruption and neurodevelopmental problems. The analysis showed that children who had been exposed to higher levels of chromium and styrene were at a nearly two-fold greater risk of developing autism.
Previous studies have teased at a link between autism and air toxins, but the new study offers a more compelling case, scientists say. The study included "two types of controls, which provided a comparison of representative air toxics in neighborhoods of those children with and without ASD," explained Dr. Talbott.
"Our results add to the growing body of evidence linking environmental exposures, such as air pollution, to ASD," added Talbott. "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."