Evaluation of DNA damage in the oral mucosa of tobacco users and non-users by 32P-adduct assay.

Tobacco and its combustion products contain several known or potential human carcinogens and studies are now beginning to emerge for detecting DNA and protein adducts in tobacco users. A highly sensitive 32P-adduct assay, capable of measuring a wide spectra of aromatic and/or hydrophobic DNA adducts, was used to evaluate tobacco use-related adducts in human oral mucosal cells. Two volunteer groups of people participated: one, a random group of cigarette smokers (n = 28) with non-smoker controls (n = 13) from our Institute, and the other, a fisherfolk community of tobacco chewers (n = 19) with appropriate non-chewer controls (n = 15) from Bombay. The cells were dislodged from the oral cavity with either a cotton swab or a toothbrush. One to as many as 16 adduct spots in the range of 5-200 amol/micrograms DNA were detected in tobacco users as well as non-users. No adduct spot was detected in the tobacco users' samples that was not present in the controls, suggesting that tobacco use may not be responsible for the formation of these DNA adducts detected in the oral mucosa. The chromatographic behavior of the oral mucosal DNA adducts by selective PEI--cellulose TLC and their extractability in 1-butanol suggest that they have an aromatic and/or hydrophobic moiety and two of the major adducts have been tentatively assigned as aromatic amine derivatives. We have discussed various possibilities of endogenous and/or exogenous factors being involved in the formation of these adducts.