ABSTRACT
The skin is a major interface between the environment and the body. Many investigations of its barrier functions by means of pharmacokinetic methods have been performed and have demonstrated that the skin is a very effective barrier against most potential environmental hazards. However, the awareness of multiple functional activities of this organ such as its capability (1) to mediate enzyme-dependent xenobiotica metabolism, (2) to express speci c transporter proteins for in ux as well as for ef ux into or out of its cells, (3) of multiple activities as an immunocompetent organ including the antigen-presenting Langerhans cells, and (4) of interactions of these cells for the protection of the body against the hazards of ultraviolet (UV) radiation has resulted in new and additional concepts about how the skin works as a barrier organ [1,2]. In addition, new technologies such as quantitative real-time PCR or the gene-array technique, which can be used for human in vivo studies, have offered superb possibilities to analyze the multiple capabilities of this complex organ system. These developments have also led to new avenues of research in dermatotoxicology and
may provide powerful instruments for dermatotoxicological risk assessments.
