Percutaneous absorption of volatile solvents following transient liquid exposures II. Ethanol

The permeation of neat ethanol through split-thickness cadaver skin was measured in non-occluded Franz cells placed in a fume hood. The test compound spiked with 14C radiolabel was applied to skin using four doses ranging from 6.33 to 50.6 μL/cm2 (5–40 μL over an area of 0.79 cm2). Additional gravimetric experiments were conducted with ethanol and benzene to determine the evaporation mass transfer coefficient. The experimental data were analyzed by non-linear regression analysis using a previously developed diffusion model in order to ascertain the optimal values of two adjustable parameters, the fractional deposition depth (fdep) and the permeant diffusivity inside the stratum corneum (DSC). Constant diffusivity and variable diffusivity models were considered. Both models were able to describe the combined observations from absorption data from three of the four applied doses. The best correlation between the experimental data and model predictions was observed with the variable diffusivity model.