Prenatal exposure to ambient pesticides increases the risk for autism spectrum disorder (ASD) in children, per study results published in the British Medical Journal.

Investigators obtained the records of patients with ASD from the California Department of Developmental Services. Data collection included patients with comorbid intellectual disability. Each case was matched with their respective birth record extracted from the Office of Vital Statistics. Randomly selected control records were matched to each case 10:1 by birth year and sex. The California-mandated Pesticide Use Reporting system was used to develop a geographic information system tool. Residential birth addresses, as listed on birth certificates, were geocoded to estimate prenatal and infant exposure to pesticides. The study examined 11 high-use pesticides based on prior implication in neurodevelopmental toxicity. Logistic regression analyses were conducted to estimate the association between ASD and each exposure.

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A total of 2961 individuals with ASD, including 445 with intellectual disability, were matched with 35,370 controls. Sociodemographic characteristics were similar in both groups, and the majority of participants (81.2% to 82.6%) were men.

The risk for autism spectrum disorder in all cases was associated with prenatal exposure to glyphosate (odds ratio [OR], 1.16; 95% CI, 1.06 to 1.27), chlorpyrifos (OR, 1.13; 95% CI, 1.05-1.23), diazinon (OR, 1.11; 95% CI, 1.01-1.21), malathion (OR, 1.11; 95% CI, 1.01-1.22), avermectin (OR, 1.12; 95% CI, 1.04-1.22), and permethrin (OR, 1.10; 95% CI, 1.01-1.20). In a similar fashion, the risk for autism spectrum disorder with intellectual disability increased with prenatal exposure to glyphosate (OR, 1.33; 95% CI, 1.05-1.69), chlorpyrifos (OR, 1.27; 95% CI, 1.04-1.56), diazinon (OR, 1.41; 95% CI,  1.15-1.73), permethrin (OR, 1.46; 95% CI, 1.20-1.78), methyl bromide (OR, 1.33; 95% CI, 1.07-1.64), and myclobutanil (OR, 1.32; 95% CI, 1.09-1.60). Exposure during the first year of life was associated in a similar fashion with ASD with intellectual disability; odds of diagnosis were particularly pronounced for glyphosate (OR, 1.34; 95% CI, 1.03-1.74) and permethrin (OR, 1.31; 95% CI, 1.07-1.62) exposure.

“Further research should be translational and integrate experimental and epidemiological approaches to further elucidate underlying mechanisms in the development of the disorder,” researchers concluded.

Reference

von Ehrenstein OS, Ling C, Cui X, et al. Prenatal and infant exposure to ambient pesticides and autism spectrum disorder in children: population based case-control study. BMJ. 2019;364:l962.