Children with autism spectrum disorder, a range of conditions characterized by social deficits and communication difficulties, were more likely to have been exposed to higher levels of certain air toxics during their mothers' pregnancies and the first two years of life compared to children without the condition, according to preliminary findings presented today at the American Association for Aerosol Research annual meeting in Orlando.
Other epidemiologists have linked everything from living near farms to organic food to autism, and such studies don't actually measure anything, they just find a map of autism and then correlate it to an environmental factor, in this instance pollution and autism instances in southwestern Pennsylvania.
Evelyn Talbott, Dr.P.H., professor of epidemiology at the University of Pittsburgh, and colleagues analyzed data on families with and without ASD living in six southwestern Pennsylvania counties. They correlated autism with increased levels of chromium and styrene. They interviewed 217 families of children with ASD and compared these findings with information from two separate sets of comparison families of children without ASD born during the same time period within the six-county area. The families lived in Allegheny, Armstrong, Beaver, Butler, Washington and Westmoreland counties, and the children were born between 2005 and 2009.
For each family, the team used the Environmental Protection Agency's (EPA) National Air Toxics Assessment (NATA) to estimate the exposure to 30 pollutants known to cause endocrine disruption or neurodevelopmental issues.
Based on the child's believed exposure (they didn't actually measure anything in anyone) to concentrations of air toxics during the mother's pregnancy and the first two years of life, the researchers noted that children who fell into higher exposure groups to styrene and chromium were at a 1.4-2X greater risk of ASD, after accounting for the age of the mother, maternal cigarette smoking, race and education. Other NATA compounds associated with increased risk included cyanide, methylene chloride, methanol and arsenic.
Styrene is used in the production of plastics and paints, but also is one of the products of combustion when burning gasoline in vehicles. Chromium is a heavy metal, and air pollution containing it typically is the result of industrial processes. Cyanide, methylene chloride, methanol and arsenic are all used in a number of industries or can be found in vehicle exhaust.
"Our results add to the growing body of evidence linking environmental exposures, such as air pollution, to ASD," said Dr. 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."
Additional investigators on this study were Vincent Arena, Ph.D., Judith Rager, M.P.H., Ravi Sharma, Ph.D., and Lynne Marshall, M.S., all of Pitt.