Gas chromatographic analysis of cloth patches treated with permethrin (0.125 mg/cm2) and worn by test subjects showed that 24–48% of the chemical remained after 10–30 days of wearing. Only a few minor degradation products were detected. However, bioassay of these patches against Aedes aegypti(L.) and Anopheles quadrimaculatus Say showed that knockdown time of the worn patches was ca. 5-fold longer than that for unworn patches after 30 days. Both the chemical and biological assays indicated that the greatest loss of permethrin from the patches occurred within the 1st 10 days. Aging without wearing did not appreciably reduce the amount of permethrin in the patches during the 30 days of the test. Permethrin appears promising as a clothing impregnant for protection against biting arthropods.
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Schreck et al. (1980) studied this question.