Detection of DNA adducts by 32P postlabeling following chronic exposure of rats to snuff

A surgically created canal was used as a reservoir for instillation of snuff into the lower lip of rats for 10 weeks. DNA was isolated and digested with micrococcal nuclease/spleen phosphodiesterase. Polar DNA adducts were detected in all tissues examined when digests were fractionated by high performance liquid chromatography (HPLC), 32P postlabeled, 3′ dephosphorylated and analyzed by two-dimensional thin layer chromatography (TLC). DNA adducts derived from aromatic carcinogens were not detected when digests were 32P postlabeled and analyzed by four-dimensional thin layer chromatography. These results suggest that non-aromatic agents initiate carcinogenesis following exposure to snuff. The adduction to DNA in organs of the gastrointestinal tract and the kidneys indicates that snuff usage results in systemic exposure to carcinogens and may contribute to the incidence of neoplasms in organs outside the oral cavity.