Study Links Pesticide Exposure in Pregnancy to Autism (Reuters Health)

“Ours is the third study to specifically link autism spectrum disorders to pesticide exposure, whereas more papers have demonstrated links with developmental delay,” said lead author Janie F. Shelton, from the University of California, Davis. There needs to be more research before scientists can say that pesticides cause autism, she told Reuters Health in an email. But pesticides all affect signalling between cells in the nervous system, she added, so a direct link is plausible.

“We already knew from animal studies as well as from epidemiologic studies of women and children that prenatal exposure (to pesticides) is associated with lower IQ,” Landrigan told Reuters Health. “This study builds on that, uses the population of a whole state, looks at multiple different pesticides and finds a pattern of wide association between pesticide exposure and developmental disability.”

“One lesson or message for parents is to minimize or eliminate use of pesticides in their own homes,” Landrigan said.

Developmental delay, in which children take extra time to reach communication, social or motor skills milestones, affects about four percent of U.S. kids, the authors write. The Centres for Disease Control and Prevention estimates that one in 68 children has an ASD, also marked by deficits in social interaction and language.

Children of mothers exposed to organophosphates were 60 percent more likely to have an ASD than children of non-exposed mothers, the authors report in Environmental Health Perspectives.

Autism risk was also increased with exposure to so-called pyrethroid insecticides, as was the risk for developmental delay. Carbamate pesticides were linked to developmental delay but not ASDs.

For some pesticides, exposure seemed to be most important just before conception and in the third trimester, but for others it didn’t seem to matter when during pregnancy women were exposed.

Dr. Philip J. Landrigan speculated that the pesticides probably drifted from crops through the air, and that’s how pregnant women were exposed.    Landrigan directs the Children's Environmental Health Centre at the Icahn School of Medicine at Mount Sinai in New York and was not involved in the new study. The new study did not measure airborne pesticide levels, however. For city-dwelling families, instead of spraying for cockroaches every month, integrated pest management is a better choice. That approach makes chemical pesticides the last resort - first steps are to seal up cracks and crevices in the home, clean up food residue and try relatively non-toxic options, like roach motels. If there’s one thing that parents can control it’s what comes into their home, he said.

 “It would be a great first step to stop using organophosphates and pyrethroids inside the home,” Shelton agreed.