The persistence of benzo[a]pyrene diol-epoxide deoxyguanosine adduct in mouse skin and its disappearance in rat skin.

Male Swiss mice and Wistar rats, susceptible and resistant, respectively, to the carcinogenic effects of benzo[a]pyrene, were treated topically with 250 nmol/mouse and 1000 nmol/rat of tritium labelled benzo[a]pyrene (BaP). The initial formation of BaP diol-epoxide deoxyguanosine adduct was approximately similar in the skin epidermis of the two species. After 3 weeks, the persistence of some 6.5% of initial BaP diol-epoxide deoxyguanosine was observed in mouse skin DNA, while this adduct was completely removed from DNA of rat skin. The total excision of BaP diol-epoxide deoxy-guanosine adduct in rat epidermis may contribute in part for the relative resistance of rat skin to the carcinogenic actions of BaP.