Fate of ethanol topically applied to skin.

Ethanol is a major component of many aerosol sprays and consumer products that are designed to contact the skin. It is theoretically possible that small amounts of ethanol from alcohol-based sprays can be absorbed across the skin or inhaled during spraying. In order to assess the potential systemic dose, three parameters were measured: the evaporation of [14C]ethanol from the skin surface, the in vitro penetration of [14C]ethanol through excised pig skin and the ethanol concentration in the blood of human volunteers following simulated use of an alcohol based deodorant spray. The rate of evaporation from Benchkote and whole pig skin was similar (t(1/2)=13.6 sec and 11.7 sec, respectively) while that from glass was longer (t(1/2)=24.8 sec). Ethanol penetration through pig skin in vitro was greater in occluded cells than in non-occluded cells (2.19 mg/cm(2) and 0.10 mg/cm(2) in 24 hours, respectively). At the maximum flux seen in this experiment under occlusion, the amount of ethanol penetrating from a 1 m(2) area of skin would give a blood alcohol level of about 4 mg% in a 70-kg man. In the human use study, none of the blood samples taken from 16 human volunteers exhibited a detectable level of alcohol. These studies provide evidence that a systemic dose of ethanol is likely to be very low after the use of formulations delivering ethanol to the skin.