The percutaneous absorption and skin distribution of lindane in man

1 The absorption and distribution of lindane through skin was examined using human volunteers. Two different preparations were employed, one with acetone as the vehicle and the other, a commercial product, consisting primarily of white spirit as the solvent base.

2 The mean peak plasma concentrations of lindane following exposure to the acetone and white-spirit based applications were 0.91 and 0.47 ng/ml, respec tively. The similarity between these levels did not reflect the 40-fold higher dose of lindane in the acetone vehicle. White spirit enhanced the penetration of lindane with respect to the acetone vehicle, high lighting the influence of vehicle upon percutaneous absorption. Low levels of trichlorophenol glucuronide metabolites, but no lindane, were detected in the urine.

3 The exposure site was washed at 6 h to mimic a decontamination procedure at the end of a working day. The proportion of the applied dose unabsorbed by 6 h was 80% and 10% for the acetone and the white spirit-based formulation, respectively. Small areas of the exposed site were tape stripped at 6 and 24 h to assess any lindane that may be associated with the stratum corneum. High levels were observed in the stratum corneum at 6 h exposure (up to 30% of the applied dose for the white spirit based formulation). However, this level had decreased by 24 h (by at least 90% of the amount found at 6 h). A gauze or gauze/shirt combination covering the application site between 6 and 24 h did account for some of this loss of lindane from the stratum corneum attributed to friction and removal of exfoliated cells. The unaccounted propor tion was presumed to have been absorbed through the skin into the systemic circulation. This demonstrates the absorption of chemicals can occur from a depot in the stratum corneum even following a wash proce dure.