The risk that a child would develop autism appeared to be highest for women who lived near farms, golf courses and other public spaces that were treated with pesticides during the last three months of their pregnancies.
“Many of these compounds work on neurons. When they work on the insect, they’re dealing with the nervous system of the insect and basically incapacitating it,” said study author Irva Hertz-Picciotto, an environmental epidemiologist at the MIND Institute at University of California, Davis.
In adults, the brain is protected from many chemical exposures thanks to special filters that prevent many substances from crossing from the blood into the brain.
Hertz-Picciotto says that in young children, this blood-brain barrier isn’t fully formed, which may allow pesticides to reach vulnerable nerve cells just as they are making vital connections to each other.