ABSTRACT
Understanding and quantifying the processes associated with chemical penetration into and through the skin is important in both pharmacology and toxicology. The human species is of primary interest; however, laboratory animals are often used as surrogates, particularly in toxicologic studies. Thus, understanding differences between species is important for extrapolating laboratory-based data to humans in a meaningful way. In vivo studies are advantageous over in vitro studies in which the intact skin has blood fl ow, is metabolically active, and possesses nervous and humoral responses. Traditional analysis of in vivo skin penetration has involved the estimation of the amount of chemical that has penetrated using either chemical blood concentrations or the amount excreted following dermal exposure. These methods are descriptive due to their secondary indication of chemical concentration that has penetrated into or through the skin. The applicability of these results is limited to the specifi c experimental design and the similarities between the laboratory species chosen and humans.
