Pollution, insecticides may increase risk of autism

Three studies link autism with environmental factors

The risk of having a child with autism increases when his or her mother is exposed to environmental factors such as air pollution when pregnant, according to three studies presented at last week's International Society for Autism Research conference.

According to the Wall Street Journal, the new studies lend strength to the theory that environmental influences before birth contribute to the risk for the condition, although the studies could not definitively prove that the influences caused autism.

  • For one study, Harvard School of Public Health researchers used Environmental Protection Agency data to compare the pollution levels in areas where 330 women reported giving birth to a child with autism to areas where 22,000 women reported giving birth to a child that did not have autism. They found that a mother's exposure to high levels of certain air pollutants—such as diesel particles—increased the risk of having a baby with autism by 30% to 50%. Lead researcher Marc Weisskopf said that the consistency of his findings "certainly makes me start to feel much more certain that we're on a path to finding something environmental that's playing a role here."
  • In a second study, University of California-Davis (UC-Davis) researchers compared the mothers of 510 children with autism to the mothers of 341 children without autism. They found that women who took iron supplements before getting pregnant or early in the pregnancy were 40% less likely to have a child with autism as opposed to women who did not.
  • Another UC-Davis study found that a link between a mother's exposure to household insecticides while pregnant and her risk of having a child with autism.  

"The exciting thing about looking at environment, or environment and genes in conjunction with each other, is this provides the possibility of intervention," notes Irva Hertz-Picciotto, lead author of the UC-Davis study on insecticides (Wang, Journal, 5/6).

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