Citing high levels of p,p’-dichlorodiphenyl dichloroethylene (DDE) in mothers whose children were later diagnosed with autism, researchers indicate evidence for a relationship between the insecticide metabolite and the neurodevelopmental disorder, according to a study published in the American Journal of Psychiatry.

Researchers used serum samples, taken between months 2 and 4 of pregnancy, from mothers registered in the Finnish Maternity Cohort who had children in the Finnish Prenatal Study of Autism. For this analysis, there were 778 children diagnosed with autism and 778 matched control children. Serum samples were analyzed through gas chromatography and mass spectrometry to quantify the levels of persistent organic pollutants, focusing on p,p’-DDE and polychlorinated biphenyls.

In general, maternal age (P =.01), maternal parity (P =.001), and family history of psychiatric disorders (maternal P =.003; parental P =.02) significantly increased the odds of a child being diagnosed with autism. Levels of p,p’-DDE were higher in mothers of children with autism than in mothers of children in the control group (mean levels=1032 pg/mL vs 811 pg/mL, respectively), and levels of polychlorinated biphenyls were higher in mothers of autistic children than mothers of control group children (mean levels=1022 pg/mL vs 999 pg/mL, respectively). When levels of p,p’-DDE were in the top 75% of the distribution, the odds of a child being diagnosed with autism increased 32% (odds ratio=1.32, 95% CI, 1.02-1.71, P =.03), and this risk increased further for male children (odds ratio=1.35, 95% CI, 1.02-1.80, P =.04). Increased levels of polychlorinated biphenyls did not elicit an increased risk for autism.

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Future studies need to examine the effects of p,p’-DDE on intellectual disabilities and control for potential serum lipid biases.

In conclusion, the researchers established the first biomarker-based evidence for “an association between maternal levels of p,p’-DDE and odds of autism in offspring.”

This study was supported by the National Institute of Environmental Health Sciences.


Brown AS, Cheslack-Postava K, Rantakokko P, et al. Association of maternal insecticide levels with autism in offspring from a national birth cohort. [published online August 16, 2018]. Am J Psychiatry. doi:10.1176/appi.ajp.2018.17101129

This article originally appeared on Psychiatry Advisor