A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Summer, 2018 | Number 3, Volume 32

U.S., Finnish researchers implicate insecticide DDT in autism

Children with elevated exposure before birth to the insecticide DDT have increased rates of autism, according to a large-scale, multinational study. 

DDT was banned decades ago in the United States and many other countries, including Finland, but it persists in the environment. To see if the insecticide plays a role in autism, researchers in the U.S. and Finland reviewed data from 778 cases of autism identified through the Finnish Maternity Cohort. They matched the mother-child pairs to mothers of children who did not develop autism, analyzing blood samples taken during pregnancy for the presence of the DDT metabolite DDE. In addition, they analyzed the samples for the presence of PCBs, another class of chemicals that persists in the environment. 

The researchers found that the odds of having a child diagnosed with both autism and intellectual disability more than doubled for mothers with DDE levels in the highest quartile. The odds of having a child with any form of autism were nearly one-third higher for the highest-exposure group than for controls. The researchers found no association between PCBs and autism. 

Lead author Alan Brown says, “We think of these chemicals in the past tense, relegated to a long-gone era of dangerous 20th-century toxins. Unfortunately, they are still present in the environment and are in our blood and tissues. In pregnant women, they are passed along to the developing fetus. Along with genetic and other environmental factors, our findings suggest that prenatal exposure to the DDT toxin may be a trigger for autism.” 

The researchers speculate that DDE may increase autism risk because it increases the odds of preterm birth—a risk factor for autism—and because it inhibits androgen receptor binding, a finding also seen in a rat model of autism.


Citations

“Association of maternal insecticide levels with autism in offspring from a national birth cohort,” Alan S. Brown, Keely Cheslack-Postava, Panu Rantakokko, Hannu Kiviranta, Susanna Hinkka-Yli-Salomäki,, Ian W. McKeague, HeljäMarja Surcel, and Andre Sourander, American Journal of Psychiatry, August 16, 2018 (online). Address: Alan Brown, [email protected]

—and—

 “First biomarker evidence of DDT-autism link,” news release, Columbia University Mailman School of Public Health, August 16, 2018.