Current Scientific Literature Suggests the Need for Re-Evaluation of Existing Regulation Regarding Pyrethroid Insecticides, Including Cypermethrin

Pyrethroids are insecticide derivatives from a botanical compound produced by plants in the genus Chrysanthemum. Known as pyrethrum, this natural insecticide acts on voltage-sensitive ion channels within a neuron’s membrane, where they delay channel closing and thereby overstimulate neurons, resulting in tremors and death in target insects. In the pest control industry, pyrethrum derivatives have been chemically modified to increase their resilience to light degradation, allowing them to linger in the environment and continue pest control after application. Additionally, artificial pyrethroids like cypermethrin, allethrin, and permethrin have been altered to increase their toxicity to insect populations.

Though these toxins are advertised for their efficacy in controlling common insect pests, their potential impact on human health should not be ignored. It has been suspected that the pyrethroid cypermethrin may influence offspring neurodevelopment and risk for neuropsychiatric disorders like autism spectrum disorder, attention deficit hyperactivity disorder, and schizophrenia. However, most recent interim reregistration of the pyrethroid cypermethrin by the US Environmental Protection Agency (EPA) does not address the pesticide’s potential impact on neuropsychiatric risk. This brief literature review aims to summarize and publicize current research on cypermethrin and neurodevelopment, especially as it relates to cumulative risk in marginalized communities. Given the complex nature of neuropsychiatric disorders, and the numerous environmental factors that can contribute to risk for these diseases, future EPA decisions should consider available studies investigating the effects of exposure to pyrethroid insecticides, their impact on neurodevelopment, and the co-occurrence of their use with additional socioeconomic vulnerabilities.