What is being sprayed?
Permethrin is the main chemical agent in Biomistthe pesticide being used to kill adult mosquitos throughout the country including Northeast Ohio. It has been registered with the EPA since 1977. It resembles pyrethrins chemically, but is chlorinated to increase its stability. Although the acute toxicity of the mixture is less than that of natural pyrethrins, the cis-isomer is considerably more toxic. Compared to other pyrethroids, permethrin is very stable, even when exposed to ultraviolet light.
Permethrin is strongly absorbed in soil and other organic particles, with half-lives in soil of up to 43 days. When used as a termiticide, permethrin can persist up to 5 years.
Permethrin received an EPA toxicity rating of II (I= most toxic, IV= least toxic), and carries either the word WARNING OR CAUTION on its label, depending on the formulation. While it is not extremely toxic to humans, there are numerous reports of transient skin, eye and respiratory irritation. Like all pyrethroids, permethrin is a central nervous system poison. Workers and researchers report tingling in face and hands, and some report allergic reactions.
Based on studies demonstrating carcinogenicity, EPA ranks permethrin as a class C, or possible human carcinogen (U.S. EPA, 1997). Other studies have shown effects on the immune system, enlarged livers and at high doses, decreased female fertility and endocrine disruption. Permethrin is extremely toxic to aquatic life, bees and other insects. It should not be applied in crops or weeds where foraging may occur (ETN, Permethrin, 1996)
Source: Shaker Heights West Nile Task Force, "Summary Report"