A chemical commonly used to repel mosquitoes carrying the Zika virus and a commonly used insecticide has been linked to reduced motor function in infants.
Researchers from the University of Michigan have found that exposure to naled through their mothers during pregnancy was associated with 3-to-4 percent lower fine motor skills scores at age nine months for those in the top 25 percent of naled exposure, compared with those in the lowest 25 percent of exposure. Infants exposed to chlorpyrifos also scored 2-to-7 percent lower on a variety of gross and fine motor skills.
“Motor delays in infancy may be predictive of developmental problems later in childhood,” first author Monica Silver, a graduate student research assistant and research fellow in the School of Public Health Department of Environmental Health Sciences, said in a statement. “The findings may help inform policy as the debate over use of these chemicals continues.”
The researchers also found that females are more sensitive to the negative effects than males.
Naled has been used in several states to fight the mosquito that transmits Zika, while chlorpyrifos is used on vegetables, fruit and other crops to control insects.
Both of the chemicals are organophosphate insecticides, which is a class of chemicals that also includes nerve agents like sarin gas. These insecticides inhibit an enzyme involved in the nerve signaling process, paralyzing insects and triggering respiratory failure.
They also may adversely impact health through other mechanisms at lower exposure levels that are commonly encountered in the environment.
The researchers examined the umbilical cord blood of approximately 240 mothers, looking for exposure to 30 different organophosphate insecticides, five of which was prevalent in at least 10 percent of the samples.
The researchers found that naled affected fine motor skills or the small movements of hands, fingers, face, mouth and feet, while chlorpyrifos is associated with lower scores for both gross and fine motor skills.
Chlorpyrifos has been banned for residential use in the U.S. since 2000, and for all use in some European countries. In 2015, the Obama Administration proposed a total ban in the U.S. but two months ago the head of the Environmental Protection Agency determined there was not enough scientific evidence to support the action.