Cigarette Smoking and Urinary 3-Alkyladenine Excretion in Man

A recently developed technique to measure several 3-alkyladenines (3-alkAde) simultaneously in urine has been applied to study alkylating agent exposure arising from cigarette smoke. A volunteer who was a moderate smoker (10-32 cigarettes per day) excreted significantly more 3-methyladenine (3-MeAde) on days when he smoked than when he did not smoke. In contrast, there was no significant difference in 3-MeAde excretion in a light smoker (less than 17 cigarettes per day) on smoking compared to nonsmoking days. However, in volunteers who consumed a standardized diet low in preformed 3-MeAde, there was a smoking-related increase in 3-MeAde excretion even at low levels of cigarette use (less than 11 cigarettes per day). In the same volunteers, no evidence of smoking-related excretion of 3-(2-hydroxyethyl)adenine could be seen. In contrast, levels of urinary 3-ethyladenine (3-EtAde) increased slightly in smokers on standardized diets. Furthermore, since the normal background level of 3-EtAde was low, an exposure-dependent increase in this adduct was seen in two smokers on freechoice diets over a 15 day period. The agent(s) responsible for the increase in 3-EtAde excretion have not been identified, but preliminary results suggest that a direct-acting ethylating compound is present in tobacco smoke.