The risk for autism increases when a fetus is exposed to air pollution, according to a new study published in the journal Archives of General Psychiatry.
“Although additional research to replicate these findings is needed, the public health implications of these findings are large because air pollution exposure is common and may have lasting neurological effects,” said the researchers, led by Dr. Heather E. Volk, an assistant professor of preventive medicine at the University of Southern California in Los Angeles.
Approximately one in 88 U.S. children will develop an autism spectrum disorder, which is characterized by significant social, communication and behavioral difficulties. Although there is no one cause or cure for the disorder, scientists say genetic, biological or environmental influences may raise risk for the disorder.
To investigate whether environment plays a role in autism risk, USC researchers compared 279 children with autism to a control group of 245 typically-developing children.
They analyzed air quality data from the Environmental Protection Agency (EPA) according to the mothers’ addresses to estimate exposure to air pollution during each trimester and through the babies’ first year.
The findings showed that children who were exposed to the highest levels of traffic-related air pollution were three times more likely to have autism compared to children living in homes with the lowest exposure.
The risk was also greater among children who were exposed to higher levels of particulate matter and nitrogen dioxide.
Particulate matter is a term used to describe solid and liquid droplets found in the air that may include dust from roads, soot from combustion sources and particles formed from gas emissions. Nitrogen dioxide is emitted from gas stoves, heaters and tobacco smoke.
The study shows an association — not a cause-and-effect link. Recent research by Volk and colleagues also found children whose mothers were living within 1,000 feet of a freeway when they gave birth were more likely to develop autism.
“These articles point to an urgent need for more research on prenatal and early postnatal brain development in autism, with a focus on how genes and environmental risk factors combine to increase risk,” said Dr. Geraldine Dawson, chief science officer for Autism Speaks and a professor at the University of North Carolina at Chapel Hill.
“Despite a substantial increase in autism research publications and funding during the past decade, we have not yet fully described the causes of ASD or developed effective medical treatments for it.”
Source: Archives of General Psychiatry