A new study links autism with a common environmental chemical.
Columbia University researchers find high levels of exposure to the insecticide DDT in women seems to more than double the risk of autism in their children.
DDT has been banned in the U.S. and many other countries for more than three decades, but it’s still present in soil, groundwater and foods.
The study looked at a sample of more than one million pregnancies, where all of the women had exposure to DDT.
Researchers say they matched nearly 800 cases of autism in children born from 1987 to 2005 to women in Finland who had provided blood samples.
Their blood was tested for DDE, a substance formed as DDT breaks down.
The overall odds of autism were almost one-third higher in children born to moms with elevated DDE levels, the study found.
For women with the highest DDE levels, the risk of autism with an intellectual disability was more than double.
But while the study found a link between autism and DDT exposure, it did not prove a cause-and-effect relationship.
The researchers say they don’t know how DDT exposure might lead to autism, though they suspect the chemical may alter the function of certain genes.
The study was published in the August 16th issue of the American Journal of Psychiatry.