Food and Behaviour Research

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24 June 2014 - MedicalXPress - Study finds association between maternal exposure to agricultural pesticides and autism

Phyllis Brown

Pregnant women who lived in close proximity to fields and farms where chemical pesticides were applied experienced a two-thirds increased risk of having a child with autism spectrum disorder or other developmental delay

FAB RESEARCH COMMENT:

The related research article can be found here: 

Shelton et al 2014 - Neurodevelopmental Disorders and Prenatal Residential Proximity to Agricultural Pesticides: The CHARGE Study

Previous research has also shown links between exposure to air pollution during pregnancy and the risk of autism and related neurodevelopmental disorders. For details, see: Air pollution raises autism risk

The large, multisite California-based study examined associations between specific classes of pesticides, including organophosphates, pyrethroids and carbamates, applied during the study participants' pregnancies and later diagnoses of autism and developmental delay in their offspring. 

For the study, researchers used questionnaires to obtain study participants' residential addresses during the pre-conception and pregnancy periods. The addresses then were overlaid on maps with the locations of agricultural chemical application sites based on the pesticide-use reports to determine residential proximity. The study also examined which participants were exposed to which agricultural chemicals.

Organophosphates applied over the course of pregnancy were associated with an elevated risk of autism spectrum disorder, particularly for chlorpyrifos applications in the second trimester. Pyrethroids were moderately associated with autism spectrum disorder immediately prior to conception and in the third trimester. Carbamates applied during pregnancy were associated with developmental delay.


"This study validates the results of earlier research that has reported associations between having a child with autism and prenatal exposure to agricultural chemicals in California," said lead study author Janie F. Shelton, a UC Davis graduate student who now consults with the United Nations. "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."