Pesticide Exposure During Pregnancy Linked to Autism: Study

New research suggests that women who live near fields that were treated with pesticide during pregnancy may be more likely to have children who develop autism. 

In a study published in the medical journal Environmental Health Perspectives on June 23, researchers found that children born to mothers who were exposed to certain pesticides during pregnancy were 60% more likely to develop autism spectrum disorder (ASD) and developmental delays (DD).The results were published on June 23 in the journal .

Researchers examined nearly 1,000 children born to mothers during 1997 to 2008 in the Childhood Autism Risks from Genetics and Environment (CHARGE) Study, which was conducted at the MIND Institute at the University of California, Davis.

One in four children will develop autism, according to estimates by the U.S. Centers for Disease Control and Prevention (CDC), while developmental delays affect about four percent of children in the U.S. However, Janie F. Shelton, lead author of the study, and the team of researchers found that children with autism were more likely to have mothers who lived within one mile of areas treated with pesticides during pregnancy.

Researchers looked at data on 486 children diagnosed with autism spectrum disorder and 168 children with developmental delays, in which the kids needed extra time to reach communication, social or motor skills milestones. They found that living near areas such as crop fields, golf courses and other public places which are often treated with organophosphates, pyrethroid and carbamates increased a child’s likelihood of having developmental delays.

In the study, researchers used commercial pesticide application data from the California Pesticide Use Report, linking mother’s addresses during pregnancy to pesticide exposure. The children were studied between the ages of two to five years of age.

Pesticides work by effecting an insects nervous system, they can also affect the neurons in humans and can cause neurotoxicity.

More than one-third of the CHARGE study mothers lived within one mile of commercial areas treated with agriculture pesticides. Researchers speculate that the harmful chemicals may have drifted in the air from treated crops or fields.

Exposure during the third trimester of pregnancy, or just before conception, increased a child’s risk of developing autism or experience other delays. Risk for developmental delay, but not autism, increased for pregnant mothers living near fields treated with carbamate applications.

California is one of only a few states in the U.S. where agriculture pesticides are strictly reported and mapped by geographic area. Researchers used those maps to track exposures during pregnancy for mothers to the children in the study.

The study did not specifically measure the airborne pesticide levels or each woman’s specific exposure, which may have underestimated the true strength of the association between pesticides and the occurrence of autism.

Other Studies Have Warned of Pesticide-Autism Link

This is the third study to link autism to pesticide exposure. Research published in 2012 found exposure to common pesticides increased a child’s risk of developing brain anomalies, including enlarged sections of the right hemisphere of the brain.

An enlarged right hemisphere may be harmful to developing children and may be tied to some gender abnormalities.

Another study also published in the Environmental Health Perspectives revealed pregnant women exposed to pesticides may have premature deliveries and children with lower birth weights.

That study focused on exposure to organophosphates and linked exposure to birth weights one-third pound lighter and several days earlier than expected.

A Harvard study published in 2010 revealed a link between pesticides and the development of attention deficit hyperactivity disorder (ADHD). Children with higher levels of organophosphates in their urine were more likely to be diagnosed with ADHD.

About 40 organophosphates are used in the U.S., with nearly 73 million pounds used in 2001 alone.

In light of concerns over pesticide health risks, the U.S. Environmental Protection Agency (EPA) recently proposed new pesticide exposure rules. The rules focus on improved worker training, prevention and pesticide treatment measures.

The agency says the new rules will protect millions of agricultural workers exposed to high amounts of potentially harmful pesticides each year.