AsianScientist (Jun. 27, 2017) – A chemical currently being used to ward off mosquitoes carrying the Zika virus and a commonly used insecticide that was threatened with a ban in the United States have been associated with reduced motor function in infants, according to a study published in Environment International.
Naled is one of the chemicals being used in several US states to combat the mosquito that transmits Zika. Chlorpyrifos, around since the 1960s, is used on vegetables, fruit and other crops to control pests.
Both are insecticides called organophosphates, a class of chemicals that includes nerve agents like sarin gas. They inhibit an enzyme involved in the nerve signaling process, paralyzing insects and triggering respiratory failure. However, they may adversely impact health through other mechanisms at lower exposure levels that are commonly encountered in the environment.
Researchers tested children in China and found that exposure to naled via their mothers during pregnancy affected fine motor skills or the small movements of hands, fingers, face, mouth and feet. Chlorpyrifos was associated with lower scores for both gross (large movements of arms and legs) and fine motor skills.
“Motor delays in infancy may be predictive of developmental problems later in childhood,” said first author Monica Silver, graduate student research assistant and research fellow at the University of Michigan. “The findings may help inform policy as the debate over use of these chemicals continues.”
The researchers examined the umbilical cord blood of about 240 mothers, looking for exposure to 30 different organophosphate insecticides, five of which showed up in at least ten percent of the samples. In addition to naled and chlorpyrifos, they found methamidophos, trichlorfon and phorate.
The researchers followed the development of the babies using the well-known Peabody Developmental Motor Skill Assessment at six weeks and nine months. No deficits were noted at six weeks. The use of the Peabody tool is unique to this study. Previous research in the environmental health field has primarily relied upon motor portions of larger developmental assessment tools, while this one focused strictly on motor skills, giving a more comprehensive view.
Chlorpyrifos has been banned for residential use in the US since 2000, and for all use in some European countries. In 2015, the Obama Administration proposed a total ban in the US but two months ago the head of the Environmental Protection Agency determined there was not enough scientific evidence to support the action.
While China is the world’s largest user of pesticides, the researchers say exposure to the chemicals is a worldwide concern, especially as countries brace for another season with the Zika virus.
“Zika is a very serious public health threat. This information helps to highlight that the way we go about combating Zika and other vector-borne diseases needs to be thought out more completely in order to minimize other unintended consequences,” said Professor John Meeker, senior author and principal investigator on the project.
“For example, a focus on a more holistic integrated pest management approach may allow for the same or even improved effectiveness in reducing disease while using smaller amounts of these potentially harmful chemicals.”
While exposure to chlorpyrifos and other pesticides used on crops is widespread and may be unavoidable in some situations, the research team said consuming organic produce when feasible, and thoroughly washing all fruits and vegetables before eating them can help to reduce exposure.
The article can be found at: Silver et al. (2017) Prenatal Naled and Chlorpyrifos Exposure is Associated with Deficits in Infant Motor Function in a Cohort of Chinese Infants.
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Source: University of Michigan.
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