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Air Pollution and Autism Risk

AGRE families help uncover gene-environment interactions.

Guest post by Heather Volk, PhD, MPH, assistant professor of preventive medicine and pediatrics with the Saban Research Institute of Children’s Hospital Los Angeles and the Zilkha Neurogenetic Institute at the University of Southern California’s Keck School of Medicine. Dr. Volk’s Autism Speaks research grant focuses on autism risk, gene-environment interactions and air pollution.

As an epidemiologist, I study how environmental exposures affect children’s brain development. In particular, I’m looking at how these exposures interact with genetic, or inherited, predisposition to autism.

Research strongly suggests that genes and environment can interact to increase risk for autism. [Editor’s note: Read more about "autism risk versus cause" in this recent blog post.] But when scientists use the term “environmental,” we’re referring to many types of influences, not just chemicals in the environment. With autism, one example is a mother’s nutrition around the time of conception.

My own research focuses on exposure to air pollution during pregnancy and early infancy. In looking for a possible relationship with autism, my colleagues and I delved into a large study of children in California. We call it the CHARGE Study, for Childhood Autism Risks from Genetics and the Environment.

Using CHARGE information, we found that pregnant women who lived within a few hundred yards of a busy freeway had an 86 percent higher risk of having a child with autism. This was in comparison to women who lived farther away from freeways.

Other researchers have made similar discoveries. In 2006, scientists found an association between autism and exposure to high levels of hazardous air pollutants around the time of birth. Similarly, North Carolina researchers found an association between autism and exposure to three specific air pollutants - methylene chloride, quinoline and styrene – also around the time of birth. Still other studies have reported connections between exposure to air pollution and other learning disorders.

However, we remain at the early stages of understanding how air pollution affects brain development and how or why it may contribute to autism. 

Thanks to support from Autism Speaks, I am beginning a study that will involve the collaboration of researchers across the United States. Together we will tap into Autism Speaks Autism Genetics Resource Exchange (AGRE). AGRE collects and maintains a storehouse of genetic and other information on families with more than one child affected by autism. We’ll be contacting AGRE families and asking them to complete a short questionnaire about where they’ve lived. We’ll match this information to records of air pollution levels in the family’s area. In this way, we can study how air pollutants affect risk for autism in a more powerful way than ever before.

We hope that this research will give us new information on how air pollution affects brain development. We also hope for new insights into environmental influences and gene-environment interactions that affect autism risk.

As you know, every person with autism is unique. As a result, we need many families participating in carefully designed studies to help us learn more about this disorder. As always, our goals are to identify how autism develops and discover ways to reduce risk and improve treatments.

I want to thank Autism Speaks and its community for both supporting our research and participating in it. I look forward to reporting our results!

Thanks to the generous and passionate support of its families, donors and volunteers, Autism Speaks is funding a wealth of research through its Environmental Factors in Autism Initiative. You can explore these and other research projects using our Grant Search.

Also see Alycia Halladay’s recent blog post “Pesticide Exposure and Risk of Autism.”