First Biomarker Evidence Autism Is Linked to DDT
Megan Brooks
DisclosuresAugust 16, 2018
Elevated levels of a dichlorodiphenyltrichloroethane (DDT) metabolite in pregnant women provide the first biomarker evidence that the banned insecticide is implicated in autism in children, new research shows.
“This study provides the first evidence, using a marker of an insecticide in the blood, that a pregnant mother’s exposure to this organic pollutant is related to an increased risk of autism in her offspring. Previous studies were based, for example, on proximity to sites that were contaminated with these pollutants,” lead investigator Alan S. Brown, MD, MPH, professor of epidemiology at Columbia University’s Mailman School of Public Health and of psychiatry at Columbia University Medical Center in New York City, told Medscape Medical News.
“The study,” he said, “offers potential implications for understanding a pathway regarding how autism might develop from a prenatal exposure and could have policy implications for public health regarding testing for, and minimizing exposure to, environmental pollutants.”
The study was published online August 16 in the American Journal of Psychiatry.
Autism Trigger?DDT and other organic pollutants were widely banned in many countries decades ago, but they persist in the food chain, leading to continuous exposure among populations. The chemicals transfer across the placenta, resulting in potential prenatal exposure.
Using the Finnish Prenatal Study of Autism, a national birth cohort study, the researchers identified 778 children with autism born between 1987 and 2005 and a matched control group. Maternal serum specimens from early pregnancy were assayed for levels DDE (p,p’-dichlorodiphenyl dichloroethylene), a breakdown product of DDT.
The odds of autism were nearly one third higher among offspring of mother’s with DDE levels that were in the highest 75th percentile, after adjusting for maternal age, parity, and history of psychiatric disorders (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.02 – 1.71; P = .03).
The odds of autism with intellectual disability were increased by greater than twofold with maternal DDE levels higher than this threshold (OR, 2.21; 95% CI, 1.32 – 3.69; P = .002). There was no association between total maternal levels of polychlorinated biphenyls (PCBs) and autism.
These findings “provide the first biomarker-based evidence that maternal exposure to insecticides is associated with autism among offspring,” the investigators write.