Comparison of benzo[a]pyrene-DNA adduct levels in mouse and rat epidermis and dermis.

Male Swiss mice and Wistar rats were treated topically with 250 nmol/mouse and 750 nmol/rat of [3H]benzo[a]pyrene ([3H]BaP). The initial level of total BaP--DNA and the individual modified deoxyribonucleoside adducts were similar in the skin epidermis of the two species. The concentration of these adducts was approximately 3 times less in both mouse and rat dermis. The decreased amount of BaP bound to DNA of mouse dermis may be related to the resistance of this tissue to the carcinogenic action of BaP. The ability of both the mouse (susceptible) and rat (resistant) skin to form BaP-bound products similar in nature and ratio in the epidermal and dermal DNA, suggests that other mechanisms are involved in the difference in the biological response of epidermis versus dermis to the carcinogenic effect of BaP.