Aerial Pesticides May Increase Risk of Autism: Study

Children living in areas that are commonly sprayed with pesticides aerially may be more likely to develop autism and other similar developmental delays, according to the findings of new research. 

In a study that will be presented this weekend at the Pediatric Academic Societies annual meeting in Baltimore, researchers from Penn State Milton S. Hershey Medical Center in Pennsylvania indicate that children living in an area of New York that used aerial pesticides were 25% more likely to be diagnosed with autism.

While the findings have not yet been published in a peer-reviewed journal, the study highlights concerns about the side effects of pesticides sprayed by airplanes throughout the U.S.

Researchers focused on the number of children with autism, and similar developmental delay disorders, which were treated at pediatric clinics in two New York state areas. Eight zip codes within a swampy area were regularly sprayed by plane with pyrethroid pesticides to control mosquitoes. Another 16 zip codes used different methods to apply pesticides, such as using hoses or manually spreading granules.

Children living in the area of New York state that were exposed to aerial pesticides had a higher rate of autism than children in the neighboring areas.

The particular swampy region of central New York, much like other areas across the country, use pyrethroid aerial spraying to spray for mosquitoes to help prevent potentially severe mosquito-borne diseases, such as West Nike virus.

In the area with aerial spraying, one in 120 children was diagnosed with autism spectrum disorder (ASD), compared to one in 172 children in areas without aerial spraying.

After researchers accounted for factors like poverty levels and preterm birth rates the children in the zip codes with aerial spraying were still 25% more likely to have been diagnosed with an ASD compared to children in the other areas.

Researchers emphasized that more research is needed, and noted that the findings do not prove pyrethroid pesticides cause autism, but do suggest a link between the two. One signifigant limitation to the study is that it was unclear if the children’s mothers lived in those zip codes during pregnancy or only during their children’s childhood.

In another study published in the journal Environmental Health Perspectives in 2014, similar concerns about the link between pesticides and autism were raised, finding that pregnant women who lived near fields treated with pyrethroids were 60 percent more likely to have children who developed autism than women who did not live near pyrethroid treated areas.

Many health experts speculate that if pesticide exposure contributes to autism risk, it would most likely be during fetal development, but there is no conclusive evidence yet to support that hypothesis.

Other research has found a number of genes associated with autism risk and children with affected older siblings have a higher risk of also developing ASD.

Genes may make some children more vulnerable to autism, but the mechanism that interacts with gene expression may require the child to also be exposed to other certain environmental factors, such as pesticides or pollution, during critical windows of early brain development for the disorder to emerge.

Another 2014 study concluded children exposed to air pollution have a higher risk of developing autism and other neurological disorders.

The CDC estimates one in 68 children in the U.S. have been diagnosed with autism spectrum disorder, which includes developmental brain disorders that affect children’s behavior and ability to communicate and socialize. Symptoms include, problems with social interactions, inability to speak and focus, as well as repetitive behaviors.