Dermal absorption of the insecticide lindane (1δ, 2δ, 3β, 4δ, 5δ, 6β‐hexachlorocyclohexane) in rats and rhesus monkeys: Effect of anatomical site

Abstract

Dermal absorption of the insecticide lindane (1δ, 2δ, 3β, 4b, 5δ, 6β‐hexachlorocyclo‐hexane) was determined in rats and rhesus monkeys. Lindane is in widespread use as a 1% cream or lotion scabicide formulation and as a 1% miticide shampoo for body lice control in humans. Results obtained following our in vivo dermal absorption procedure demonstrated that 18 ± 4.1%, 34 ± 5.2%, and 54 ± 26.3% of the applied dose was absorbed following topical applications at a rate of 1.5 μg/cm ² (6.2 μg/100 μl of acetone) of the ¹⁴ C‐labeled pesticide to 4.2‐cm ² regions of the forearm (n = 8), forehead (n = 7), and palm (n = 4) of rhesus monkeys, respectively. Dose sites were washed with soapy water 24 h posttreatment. Comparative studies in rats (n = 5) dosed middorsally demonstrated 31 ± 9.5% absorption. Statistical analysis of the ¹⁴ C excretion kinetics demonstrated slower clearance of lindane from rats than monkey forearm, forehead, or palm. Intramuscular (im) injections of ¹⁴ C‐lindane gave 52 ± 7.1% recovery in monkey (n = 8) and 64 ± 5.9% in rats (n = 5), suggesting body storage of this lipophilic chemical.