Agricultural Pesticides Linked to Autism

Pregnant women who live in close proximity to fields and farms that use pesticides should be wary. A new study shows such harmful chemicals are linked to a two-thirds increased risk of having a child with autism spectrum disorder.

Researchers with the University of California (UC) Davis MIND Institute have found that pesticides, including organophosphates, pyrethroids and carbamates, lead to later diagnoses of autism and other developmental delays. Also, the associations were stronger when the exposures occurred during the second and third trimesters of the women's pregnancies.

"While we still must investigate whether certain sub-groups are more vulnerable to exposures to these compounds than others, the message is very clear: Women who are pregnant should take special care to avoid contact with agricultural chemicals whenever possible," lead study author Janie F. Shelton said in a press release.

California is a top producer in the agriculture industry, and statewide spreads about 200 million pounds of it each year.

Pesticides, while necessary to protect crops, are neurotoxic and may pose threats to brain development during gestation, potentially resulting in developmental delay or autism.

"In that early developmental gestational period, the brain is developing synapses, the spaces between neurons, where electrical impulses are turned into neurotransmitting chemicals that leap from one neuron to another to pass messages along," explained Irva Hertz-Picciotto, MIND Institute researcher and professor. "The formation of these junctions is really important and may well be where these pesticides are operating and affecting neurotransmission."

Using the California Pesticide Use Report, researchers looked at families with children between 2 and 5 diagnosed with autism or developmental delay or with typical development, most of whom live in the Sacramento Valley, Central Valley and the greater San Francisco Bay Area.

After comparing participants' addresses and pre-conception and pregnancy periods, they found a link between pesticide exposure and autism diagnosis. Organophosphates, in particular, were associated with an elevated risk.

This research has emphasized the importance of maternal nutrition during pregnancy, though it is impossible to entirely eliminate risks due to environmental exposures.

The findings were published in the journal Environmental Health Perspectives.