(Beyond Pesticides, June 13, 2017) Prenatal exposure to commonly used mosquito and agricultural insecticides is associated with decreased motor function in infants, according to a study published in Environment International by a team of Chinese and U.S. researchers. The results of the study should give pause to insecticide-heavy efforts to control mosquitoes as the season ramps up this summer and fall. Frequent spraying as part of efforts to control Zika in Southern Florida last year resulted in large protests and calls for a preventive management approach not dependent on toxic chemicals.
For the current study, over 350 pregnant Chinese mothers were tested for the presence of organophosphate pesticides in their umbilical cord blood. Researchers looked at exposure to the insecticides naled, methamidophos, trichlorfon, chlorpyrifos, and phorate. After giving birth, their children’s motor function was tested at both six and nine months of age. Tests included an analysis of the infant’s reflexes, locomotion, grasping, stationary and visual-motor integration abilities. Scores were categorized based on gross, fine, and total motor skills, and standardized quotients were created for each of the categories.
Of the over 300 mothers, roughly 240 had detectable levels of one of the insecticides in their samples. Although no differences in motor function were observed for infants at six months of age, significant impacts were seen once the tests were repeated at nine months. The most striking effects were seen with the chemicals chlorpyrifos and naled. For naled, scores for visual motor, fine motor, and fine motor quotients decreased 0.55, 0.85, and 0.90 points lower per 1 ng/mL increase in naled originally detected in an infant mother’s cord blood. With chlorpyrifos, reflexes, locomotion, grasping, VM (visual motor), GM (gross motor), FM (fine motor), TM (total motor), GMQ (gross motor quotient), FMQ (fine motor quotient), and TMQ (total motor quotient) are, respectively, 0.50, 1.98, 0.80, 1.91, 3.49, 2.71, 6.29, 2.56, 2.04, and 2.59 points lower, when comparing exposed and unexposed infants, according to the study.
Concerns about the toxicity of naled and chlorpyrifos are not new. Chlorpyrifos is the subject of a decade-long legal battle, where the Natural Resource Defense Council and Pesticide Action Network North America sued the U.S. Environmental Protection Agency (EPA), challenging its continued allowance, given evidence of neurotoxic effects. Earlier this year, EPA reversed a tentative decision made in 2015 to revoke food tolerances for the chemical, a move seen as politically motivated by the Trump administration. Past research has linked chlorpyrifos to a range of adverse health outcomes, from tremors in children, to lowered IQ, and autism.
Naled has also long been subject to scrutiny from scientists and health advocates. Last year, Beyond Pesticides sent a letter to EPA citing the inadequacies of its scientific review as outdated and incomplete, leading to significant safety concerns. A 2015 deadline the agency set for a final review decision on residential exposure to naled has still not been met. Meanwhile, reports of massive bee kills, sick residents, and studies such as these add to calls to eliminate this chemical’s use in our environment. To wit, a study published last year regarding the efficacy of naled and other mosquito adulticides in controlling Zika in Southern Florida showed very little reduction in the mosquito that carries the virus, Aedes aegypti, indicating evidence of widespread resistance.
Smart community mosquito management focuses on education and source-reduction as the primary means to manage mosquito-borne disease outbreaks. Community residents are encouraged to dump out standing water at least once a week, and effective vector control operations also eliminate standing water sources to the extent possible and, as needed, treats water bodies with least-toxic larvacides like bacillus thuringiensis. Use of mosquito adulticides have been shown to lack efficacy and should only be as a last resort temporary measure when other options have failed and there is an imminent public health threat – never as a regular course of action. Beyond Pesticides’ Mosquito Management program page has a list of resources that can help individuals and communities safely manage mosquitoes, including information on least-toxic mosquito repellents, bed nets, and proper clothing that can be used to keep mosquitoes safely at bay. Beyond Pesticides produces educational doorknob hangers available for print out or request, which can be used to educate neighbors on the adoption of pesticide-free methods for reducing mosquito populations in communities nationwide.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.