(Beyond Pesticides, June 15, 2017) Communities exposed to frequent aerial spraying for mosquito control experience elevated rates of autism diagnoses, according to new research. The study identifies the frequent use of synthetic pyrethroid insecticides, which are linked to neurocognitive and behavioral impacts, among other health effects.
Pediatric researchers at Penn State University and the University of California examined communities in eight zip codes in Onondaga County, New York with frequent aerial spray programs for mosquito control, and contrasted these findings with communities in 16 zip codes that do not employ similar pesticide use programs. According to the study, between 2007 and 2009, the average yearly pesticide burden across the eight aerial exposed zip codes was approximately 11,000 kilograms, compared to approximately 4,000 kilograms of pesticide exposure across the 16 control zip codes. The study finds that the zip codes with frequent aerial pyrethroid exposure are 37% more likely to have higher rates of childhood developmental delays and autism spectrum disorder. The researchers acknowledge that the study establishes a correlational, not a causal, link between pyrethroid exposure and autism/developmental disorders, it adds to a growing body of research demonstrating an exposure-effect relationship between the two.
Other studies have similarly linked developmental disorders and autism to pyrethroid exposure. In 2014, researchers found that pregnant women who lived within a mile of agricultural fields treated with pyrethroid insecticides are more likely to have their child develop autism. The study found that living near a field where pyrethroids were applied during a woman’s third trimester corresponded with an 87% increased risk of having a child with autism. Another study, published by a team of French scientists in the journal Occupational and Environmental Medicine, links childhood behavioral problems to pyrethroid insecticide exposure. This past Tuesday, Beyond Pesticides reported on a study published by a team of Chinese and U.S. researchers that found prenatal exposure to commonly used mosquito and agricultural insecticides is associated with decreased motor function in infants.
Researchers hypothesize that behavioral disorders are rooted in changes to a child’s brain. Because pyrethroids act on sodium channels, increased sodium influx may result in effects to synaptic plasticity, which is important in the development of learning and memory. Scientists infer that pyrethroid exposure may also alter the transport of dopamine throughout the brain. Dopamine is an important neurotransmitter, responsible for a wide variety of functions in the brain and body.
In addition to exposure through mosquito spraying, more and more synthetic pyrethroids are sold to consumers for home use pest control, with claims that they are lower toxicity or as safe as chrysanthemum flowers, from which natural pyrethrum is derived. These chemicals are showing up in increasing concentrations in children’s urine, as reported by recent research at University of California, Davis. In addition to their use in home pest control products like RAID®, they are commonly found in head lice shampoos marketed for children, despite studies indicating that 99.6% of lice are resistant to treatment by the commonly used synthetic pyrethroid permethrin.
In light of the identified hazards and unknown effects of exposure to pyrethroids, Beyond Pesticides urges local and state officials to consider more closely the lack of efficacy associated with community spray programs. Beyond Pesticides encourages an integrated approach to mosquito management that focuses on prevention through public education encouraging frequent removal of standing water, larviciding, and use of repellents. If prevention measures are enforced, the need to spray should be extremely limited, and balanced against the potential public health impacts of hazardous pesticides. Community-based programs should encourage residents to employ these effective techniques, focus on eliminating breeding sites on public lands, and promote monitoring and action levels in order to determine what, where, and when control measures might be needed. Contact Beyond Pesticides for 25 free mosquito doorknob hangers to encourage best management practices in your neighborhood.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.