ABSTRACT
During skin exposure studies, it would be useful for scientists to be able to estimate the skin absorption of a chemical. Numerous studies have examined the relationship of various properties of chemicals that might aid in this endeavor. Reasonable correlations have been obtained between percutaneous absorption and lipid/water partition coefficients for certain homologous series of compounds: phenols, 1 alcohols, 2 steroids, 3 and hair dyes. 4 In these studies, percutaneous absorption was expressed in terms of a permeability constant (Kp) measured from an aqueous vehicle. In this way, one could extrapolate between doses, because a Kp value by definition is the flux normalized for concentration. The octanol/water partition coefficient (Kow) is now most commonly used as a measure of lipophilicity, because numerous published Kow values are available and because methods are available for Kow estimations based on chemical structure.
