Permethrin is applied to the forearm of the subject and remains for 8 hours. The exposed area is then washed with soap and water several times. 24 hour urine samples are collected at daily intervals for 192 hours. Blood and saliva samples are taken at pre-dose, 1, 3, 6, 9 12, 24, 48, 72, 96, 120, 144, 168 and 192 hours. Subjects must return to the clinic daily to drop off urine collections and have blood and saliva samples taken.