A pesticide that’s often used in and around homes across the U.S. has now been linked to an increased risk of ADHD.
In a report published in the Journal of the Federation of American Societies for Experimental Biology, Rutgers scientists and colleagues from Emory University, the University of Rochester Medical Center, and Wake Forest University released the results of a study showing that mice exposed to the pyrethroid pesticide deltamethrin in utero or through lactation exhibited features of ADHD.
Deltamethrin products are very popular with pest control operators in the U.S. They’re often sprayed lawns or golf courses to kill a wide range of insects, and sometimes used indoors as a spot or crack treatment.
The synthetic pyrethroid is considered to be part of a safer class of pesticides. But it has been shown to be neurotoxic to humans, who can be exposed to the chemical by touching it or breathing it in. It has also been shown to pass through a woman’s skin and blood and into her breast milk. Young children and pregnant women are more susceptible to exposure from the pesticide because their bodies don’t metabolize the chemicals as quickly.
The researchers from the study say it provides “strong evidence” that exposure to pyrethroid pesticides, including deltamethrin, may be a risk factor for ADHD. The mice in the study displayed symptoms such as dysfunctional dopamine signaling to the brain, hyperactivity, working memory, attention deficits and impulsive-like behavior.
And the effects didn’t wear off once the chemical left the young mice’s bodies — according to the research, the mice continued to exhibit ADHD-like behaviors into adulthood, even after the pesticide had left their system. Boy mice were also more susceptible to ADHD symptoms — which mirrors what researchers have observed in children with ADHD.
The findings were corroborated by further evidence from analysis of Centers for Disease Control, National Health and Nutrition Examination Survey data, which showed that children with higher pyrethroid pesticide metabolite levels in their urine were more than twice as likely to be diagnosed with ADHD.
While the authors note that the findings should have implications for how the pesticides are used, and that exposure in higher risk children should be limited, they also say that human studies will be needed to determine how exposure affects the developing fetus and young children.