Study Finds Fine Particulate Air Pollution Associated with Increased Risk of Autism

Exposure to the pollution caused by such things as car exhaust and coal-fired power plants may be associated with an increased risk of autism spectrum disorder, a University of Pittsburgh study has found.

By Jenny Wagner

Beaver County Times, Pa.

Exposure to the pollution caused by such things as car exhaust and coal-fired power plants may be associated with an increased risk of autism spectrum disorder, a University of Pittsburgh study has found.

The research, conducted by Pitt's Graduate School of Public Health, examined exposure to a type of fine particulate air pollution known as PM 2.5, which includes dust, dirt, soot and smoke.

The particles in such pollution are less than 2.5 micrometers in diameter -- or 1/30th the average width of a human hair -- and are easily inhaled into the lungs and then absorbed into the bloodstream, said Evelyn Talbott, Dr.P.H., lead author and professor of epidemiology at Pitt.

Talbott and her team interviewed the families of 211 children with autism and 219 children without autism born between 2005 and 2009 and living in the six-county southwestern Pennsylvania region, which includes Allegheny and Beaver, and then compared estimated average exposure with pollution during pregnancy and the first two years of life.

Using information about where mothers lived and models developed by co-author Jane Clougherty, Sc.D., Talbott and her team were able to estimate individual exposure to the pollution.

The researchers found that children who fell into higher exposure groups had an approximate 1.5-fold greater risk of autism. That's also after accounting for other risk factors, such as the mother's age, education level and smoking during pregnancy.

Three other studies of pollution exposures, including two in California, have shown similar results for an increased risk of autism, which now affects one in 68 children, Talbott said.

Both genetic and environmental factors are believed to be responsible for the range of conditions, which typically are characterized by social deficits and communication difficulties. Another Pitt Public Health study last year found that children with autism also were more likely to have been exposed to higher levels of air toxics.

Talbott said things such as proximity to roadways, proximity to industry such as coal-fired power plants and coke ovens play a role in PM 2.5 exposure. So, places that are more urban, including some communities in Beaver County, typically will have higher levels of the pollution, she said.

Topography also plays a role, Talbott said, especially in hilly southwestern Pennsylvania, which has ranked among the nation's worst regions for PM 2.5 levels.

"A lot of air pollution gets trapped because if you're in a valley near a river and the air is stagnant, it tends not to move," she said.

But while the results of the population-based, case-control study indicate an association between autism and pollution, they do not prove causality, Talbott said.

Researchers know that breathing in PM 2.5 pollution causes inflammation that has been linked to cardiovascular risks, Talbott explained, but they need more clinical studies to understand the biology behind the association with autism.

"Autism spectrum disorders are lifelong conditions for which there is no cure and limited treatment options, so there is an urgent need to identify any risk factors that we could mitigate, such as pollution," Talbott said.

Based on evidence of other health risks associated with pollution, Talbott said it's her opinion that pressure should be put on legislators to push industries to clean up processes and meet air quality standards. She noted that people can monitor their air quality every day, but it's a challenge because so many people live in urban areas now.

"We're urban, social beings," Talbott said. "We're not going to go back to living in the wilderness ... so you just have to be aware that living in a community or a city does come with certain potential hazards."

The research, funded by The Heinz Endowments, is published in the July edition of the journal, Environmental Research.

Additional co-authors of the study are Vincent C. Arena, Ph.D., Judith R. Rager, M.P.H., Drew R. Michanowicz, Dr.P.H., Ravi K. Sharma, Ph.D., and Shaina L. Stacy, Ph.D., all of Pitt Public Health.

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