Intraperitoneal administration of allethrin, deltamethrin, fenvalerate, or permethrin to rats resulted in a dose-dependent decrease in the frequency of previously learned behaviors.

A technical grade formulation of d-allethrin (a cis/trans mixture) caused corrosion (Type I irritation) in the Draize assay. Two different tests on the 96.1% technical formula showed minimal irritation (category IV) in the Draize assay, tests on the 92.1% liquid formula and a similar 92.4% liquid also showed minimal (category IV) irritation. Draize tests of seven ready-to-use end products, including blends with permethrin, phenothrin, dipropyl isooctyl, PBO and NOBD, showed minimal irritation. Testing of five end-use products—one containing only allethrin, two containing a mixture of permethrin, one containing a mixture of PBO and NOBD, and one containing a mixture of allethrin, NOBD, and chlorpyrifos— Shows moderate irritation.

After application of type I pyrethroids such as permethrin and allethrin, the potential increases gradually after depolarization and reaches the threshold membrane potential for action potential generation (Lund and Narahashi, 1981a,b; Narahashi, 1962; Vijverberg et al., 1982).

The mode of action of pyrethroids can be inferred from studies using synthetic pyrethroids rather than natural mixtures. In synthetics, allethrins are the closest structural relatives to natural products.