Exposure to fine particulate air pollution during pregnancy through the first two years of a child’s life may be associated with an increased risk of the child developing autism spectrum disorder (ASD), a condition that affects one in 68 children, according to a University of Pittsburgh Graduate School of Public Health investigation of children in southwestern Pennsylvania.
“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,” said lead author Dr. Evelyn Talbott, professor of epidemiology at Pitt Public Health. “Our findings reflect an association, but do not prove causality. Further investigation is needed to determine possible biological mechanisms for such an association.”
Dr. Talbott and her colleagues performed a population-based, case-control study of families with and without ASD living in six southwestern Pennsylvania counties. They obtained detailed information about where the mothers lived before, during, and after pregnancy and, using a model developed by Pitt Public Health assistant professor and study co-author Dr. Jane Clougherty, were able to estimate individual exposure to a type of air pollution called PM2.5.
This type of pollution refers to particles found in the air that are less than 2.5 micrometers in diameter, or 1/30th the average width of a human hair. PM2.5 includes dust, dirt, soot, and smoke. Because of its small size, PM2.5 can reach deeply into the lungs and get into the bloodstream. Southwestern Pennsylvania has consistently ranked among the nation’s worst regions for PM2.5 levels, according to data collected by the American Lung Association.
Dr. Talbott and her team interviewed the families of 211 children with ASD and 219 children without ASD born between 2005 and 2009. The families lived in Allegheny, Armstrong, Beaver, Butler, Washington, and Westmoreland counties. Estimated average exposure to PM2.5 before, during and after pregnancy was compared between children with and without ASD.
Based on the child’s exposure to concentrations of PM2.5 during the mother’s pregnancy and the first two years of life, the Pitt Public Health team found that children who fell into higher exposure groups were at an approximate 1.5-fold greater risk of ASD after accounting for other factors associated with the child’s risk for ASD – such as the mother’s age, education, and smoking during pregnancy. This risk estimate is in agreement with several other recent investigations of PM2.5 and autism.
A previous Pitt Public Health analysis of the study population revealed an association between ASD and increased levels of air toxics, including chromium and styrene. Studies by other institutions using different populations also have associated pollutants with ASD.
Additional co-authors of this study are Dr. Vincent C. Arena, Ms. Judith R. Rager, Dr. Drew R. Michanowicz, Dr. Ravi K. Sharma, and Dr. Shaina L. Stacy, all of Pitt Public Health.
For more information, visit http://www.upmc.com/media/NewsReleases/2015/Pages/talbott-autism.aspx.