Preliminary research out of the University of Pittsburgh found that children with Autism Spectrum Disorders (ASD) were 1.4 to two times more likely to have been exposed to higher levels of air pollution during pregnancy and the first two years of life than children without ASD. The results of the study were presented at the American Association for Aerosol Research annual meeting in Orlando, Fla. yesterday.
To reach these results, researchers interviewed 217 families of children with ASD and compared the data with information from two separate sets of comparison families of children without ASD, all born between 2005 and 2009 and living in the Pa. counties of Allegheny, Armstrong, Beaver, Butler, Washington and Westmoreland. The team then used the National Air Toxics Assessment (NATA) to estimate exposure to 30 pollutants historically linked with neurodevelopmental issues and endocrine disruption. After adjusting for the age of the mother, race, education and maternal cigarette smoking, they found that children with ASD had a higher exposure than children without ASD, sometimes even two-fold, to styrene (used in plastics and paints and also a product of combustion when burning gas in vehicles), cyanide (which becomes airborne from car exhaust and smoking) and chromium (a heavy metal used mostly in making steel, what Pittsburgh's known for).
The correlation between these toxics, which are present in the air across the country, and ASD could be coincidental, but study leader Dr. Evelyn Talbott doesn't assume so, since the results of the study are consistent with past studies that show a link between air pollution exposure (styrene especially) and ASD.
"We are finding some consistencies between the studies, which I consider to be important," said Talbott, a professor of epidemiology at the University of Pittsburgh. "Is it proving a cause? Absolutely not. But I do think it bears further looking into."
The main limitation of the study, according to Dr. Craig Newschaffer, an epidemiologist who directs the AJ Drexel Autism Institute at Drexel University in Philadelphia, is the lack of individual-level exposure data. The researchers looked at air toxic exposure by county and merely estimated individual exposure, instead of examining the individuals directly for evidence of exposure (what they hope to do in the future).
"Getting good individual-level exposure data is challenging and expensive," said Newschaffer, who wasn't involved in the study. "Still, these findings (this study and the other similar ones) do very strongly suggest that environmental factors broadly defined are playing an important role in causing autism."
Autism Spectrum Disorders, a set of conditions that can cause everything from difficulty picking up social cues and communicating to seizures and repetitive behaviors, is now estimated to affect one out of 68 kids in America, which is a 30 percent increase since 2012, according to the Centers for Disease Control and Prevention (CDC). The severity of the condition can vary greatly along the spectrum, but can still be impairing in relationships, the workforce and life in general.
Though the cause of ASD remains unknown, many researchers assume it's genetic, environmental or both. If this research goes on to show a direct link between air pollution exposure and ASD, it could help prevent some from developing the condition, if exposure to the air toxics can be reduced or eliminated. Until then, it remains a correlation, not a causation.
