According to a new study, women exposed to pesticides during pregnancy are more likely to deliver a child with autism spectrum disorder and other neurodevelopmental disorders. The findings were published online on June 23 in the journal Environmental Health Perspectives by researchers at the University of California, Davis and UCLA.
The researchers were aided by the fact that California is one of only a few states in the US where agricultural pesticide use is rigorously reported and mapped. They note that exposure to several common agricultural pesticides during pregnancy can induce developmental neurotoxicity in humans; furthermore, it has been associated with developmental delay and autism. Therefore, they assessed whether residing near an area where agricultural pesticides during pregnancy is associated with autism spectrum disorder or developmental delay. They reviewed data from the Childhood Autism Risks from Genetics and Environment (CHARGE) Study.
The study authors explain that the CHARGE study is a population-based case-controlled study of autism spectrum disorder and developmental delay. These cases were compared to children with normal development. The study group comprised 970 participants from whom commercial pesticide application data from the California Pesticide Use Report (1997-2008) were connected to the addresses during pregnancy. The number of pounds of active ingredient applied for organophophates, organochlorines, pyrethroids, and carbamates were measured at varying distances from the home: 1.25 kilometer (km), 1.5 km, and 1.75 km. (A kilometer is 0.62 mile). They conducted a statistical analysis of confirmed cases of autism spectrum disorder (486 children) or developmental delay (168 children) and children with normal development (316 children).
The researchers found that approximately one-third of CHARGE Study mothers resided during their pregnancy within 1.5 km (slightly less than one mile) of an agricultural pesticide application. Living near an area where organophosphates were used at some point during the pregnancy was associated with a 60% increased risk for autism spectrum disorder; the risk was greater during the third trimester (last three months of pregnancy (2.0-fold increased risk) and second trimester chlorpyrifos exposure (3.3-fold increased risk) Children of mothers who resided near pyrethroid insecticide applications just prior to conception or during the third trimester were at increased risk for both autism spectrum disorder and developmental delay; the increased risk ranged from 1.7- to 2.3-fold. The risk for developmental delay was higher for women who resided near carbamate applications; however, no specific vulnerable period was determined.
The authors concluded that their study of autism spectrum disorder strengthens the evidence that links neurodevelopmental disorders to pesticide exposure during pregnancy; moreover, organophosphates, including pyrethroids and carbamates, are particularly harmful.
Take home message:
Residing in an area where pesticide exposure of any type is likely should be avoided during pregnancy and if trying for pregnancy. In fact, it would be prudent for all individuals to avoid these areas. Pesticides are available for home use. Pregnant women should not apply them and the one who applies them should wear a mask and wash his or hand s thoroughly after application. If application is via a service, vacate your residence during the spraying.