Permethrin - New Source of Safety Data
Permethrin, an insecticide, has been used and debated as an anti-insect treatment for clothing, including backpacking. This useage is most often based on 0.5% solutions, although some use higher concentrations.
It is common for someone to allege that it "might be unsafe to use this insecticide in contact with human skin". The following is an affordable medical reference ($6.99 at Borders) that has a page on Permethrin.
The Johns Hopkins Pills & Medicines - 3,000 prescription and over-the-counter medications.
On page 620 is Permethrin sold as a generic topical antiparasitic for ridding the head of lice -- including children's heads. Brand names are Nix and Elimite.
Elemite is sold as a lotion containing 5% permethrin to be applied directly to the scalp.
The Johns Hopkins book cites side effects
" SIDE EFFECTS
No serious side effects have been reported.
Burning, itching, numbness, rash, redness, stinging, swelling, or tingling of scalp. In most cases such symptoms are mild and temporary: notify your doctor if they are more troublesome or if they persist.
No less-common side effects have been reported."
By searching for the pharmacological recommendations for the drugs, Nix and Elimite, you can obtain your own information on side effects of permethrin applied directly to human scalp skin.
The section on how the drug works is below.
" How The Drug Works
Permethrin is absorbed into the bodies of lice, where it blocks nerve activity, ultimately causing paralysis and death of the lice. (The drug has no such toxic effect on humans.) "
Follow the safety instructions on any bottles of permethrin you buy for the purpose of treating garments with insecticides. Follow the military treatment guidelines for the application of high concentrations of permethrin.