Study Links Insecticide to Increased Autism Risk

The story

A new study has linked DDT – an insecticide that the Environmental Protection Agency banned in 1972 – to an increased risk for autism in children.

Specifically, the study found that if pregnant women had elevated levels of a DDT metabolite – a substance the body forms in the process of metabolism – their children were more likely to have autism.

The researchers discovered that the odds of autism with intellectual disability in children increased more than twofold for mothers whose DDT metabolite levels were in the top quartile. For the overall sample of autism cases, the odds were nearly one-third higher among exposed children.

Lingering exposure

While DDT was banned in many nations — including Finland, where the study was conducted — more than 30 years ago, it persists in the food chain because it breaks down very slowly, taking as long as several decades, the researchers explain.

The chemical transfers across the placenta in greater concentrations than those measured in the mother’s blood.

The study also evaluated another class of chemicals – polychlorinated biphenyls, or PCBs – but found no link between those and increased autism risk.

Other pesticides

Some studies have suggested that chlorpyrifos – the most widely used insecticide in the U.S. – also increases autism risk, although the research has not been conclusive and there remains no scientific consensus on the subject.

Other studies have identified higher autism rates in areas that are treated with aerial pesticide applications for mosquito control.

Ultimately, more research is necessary to determine if pesticides in general contribute to rising autism rates in the U.S.

Autism myths

One thing’s for sure: Vaccines don’t cause autism.

The widespread fear that vaccines increase risk of autism originated with a 1997 study published by Andrew Wakefield, a British surgeon. The article was published in The Lancet, a prestigious medical journal, suggesting that the measles, mumps, rubella (MMR) vaccine was increasing autism in British children.

The paper has since been completely discredited due to serious procedural errors, undisclosed financial conflicts of interest, and ethical violations. Andrew Wakefield lost his medical license and the paper was retracted from The Lancet.

What do you think?

What, if anything, should regulators do about this fresh evidence of a link between a pesticide and increased autism risk? Hit Take Action to tell your reps what you think, then share your thoughts below.

—Sara E. Murphy

(Photo Credit: iStock.com / sodafish)