Comparison of the penetration of 14 pesticides through the skin of young and adult rats.

In vivo percutaneous absorption of 14 pesticides was studied in young (33-d-old) and adult (82-d-old) female Fischer 344 rats, at three different dose levels. Carbon-14-labeled pesticides in acetone were applied to previously clipped middorsal skin. The treatment area was 2-3% of the body surface area. Penetration of the pesticides during a 72-h period ranged from approximately 1%-90%, depending on compound, dose, and age of animal. No clear age-related pattern of dermal absorption among compounds was found. Only chlordecone, folpet, and permethrin did not show significant age-dependent differences in skin penetration. Atrazine, carbaryl, chlorpyrifos, and hexachloro-biphenyl had greater absorption in the young, while carbofuran, captan, dinoseb, DSMA, MSMA nicotine, and parathion displayed greater absorption in the adult. The majority of the compounds showed dose-dependent penetration. The dose-response curves for penetration were not parallel for 8 of the 14 compounds studied.