Pesticide Exposure during Pregnancy Linked to Autism


A new study finds that pregnant women who lived within a mile of a farm where organophosphate pesticides were used had a 60 percent higher risk of having a child on the autistic spectrum.

The researchers, from the University of California at Davis’ MIND Institute, say the risk was strongest when the exposure occurred during the second and third trimesters. Environmental Health Perspectives, which published the study, says that exposure to the pesticide chlorpyrifos during the second half of pregnancy more than tripled the risk of having an autistic child.

Seven years ago, a study based in the Central Valley of California found very similar results. The UC Davis researchers say their study strenghens the past study and should remind pregnant women to be cautious. Researchers used the data from the California Pesticide Use Report, which shows what kind of pesticides are used and where and when they’re applied. Researchers then overlaid addresses of about 1,000 participants in a population-based, case-control study of children ages 2-5 with autism, developmental delays and typical development. About one-third of the mothers in the study lived within a mile of a spraying zone while they were pregnant. The rates of autistim spectrum disorders (ASD) decreased as the distance from the zones increased.

“If it were my family, I wouldn’t want to live close to where heavy pesticides are applied,” says Irva Hertz-Picciotto, senior author of the report and a professor and vice chair of the Department of Public Health Services at UC Davis.

The rate of ASD has risen to 1 in 68 children, a 30 percent increase in just two years, according to the Centers for Disease Control and Prevention. Parents should recognize that there’s a significant difference between something being identified as a “cause” of autism and something that indicates higher “risk,” and many factors are involved in the development of ASD. That said, Hertz-Picciottoe advises pregnant women who live near agricultural fields “to leave town or keep their children away or close the windows” on days when pesticides are being applied.