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PERCUTANEOUS ABSORPTION AND CHEMICAL CARCINOGENESIS

Chemical agents which are carcinogenic may enter the animal organism through three possible routes: the skin, respiratory tract and the gastrointestinal tract. In this thesis the percutaneous transfer of chemical agents which may induce cancer in the skin as well as other organ systems of man and experimental animals will be considered. The skin is: 1. An important interface between man and his environment. 2. An organ of defense and adaptation. 3. A portal of entry for chemical and biologic agents. 4. A susceptible target organ for toxic agents, even when absorbed through other routes'. 5. A uniquely accessible model system for studying a variety of important biologic phenomena including carcinogenesis. Adaptive and Defense Mechanisms The following is a brief description of adaptive and defense mechanisms. They represent important biologic characteristics of that organ system in which the carcinogenic process may occur: 1. The epidermal barrier: It is comprised of an 8 to 15 cell layer thick, non-living structure which offers a measure of resistance, although imperfect, against penetration of chemical carcinogens as well as ultraviolet