URINARY-EXCRETION OF 3-METHYLADENINE AND 3-ETHYLADENINE AFTER CONTROLLED EXPOSURE TO TOBACCO-SMOKE

The urinary excretion of the DNA alkylation products 3-methyladenine (3-MeAde) and 3-ethyladenine (3-EtAde) after controlled exposure to cigarette smoke over a period of 4 days was determined by competitive radioimmunoassay after separation by HPLC, Twenty-four hour urine samples were collected from five smokers and five non-smokers, Days 1 and 3 (control days) were without smoking, on days 2 and 4 smokers consumed 24 cigarettes each within 8 h in an unventilated room (45 m(3)) in the presence of nonsmokers. Average levels of carbon monoxide during exposure were 15-20 p.p.m., 2.8-3.5 mg/m(3) of respirable suspended particles and 75-86 mu g/m(3) of nicotine, Carboxyhemoglobin levels increased by 9.0 and 1.8% in smokers and passive smokers respectively. On control days, urinary excretion of 3-MeAde was similar in smokers and nonsmokers (4.7-6.2 mu g/24 h), Smoking resulted in a significant increase (P < 0.01) in 3-MeAde excretion (13.6-14.8 mu g/24 h); no change was observed in the average excretion of 3-MeAde by passive smokers (4.8-4.9 mu g of 3-MeAde/24 h). Baseline 3-EtAde excretion on control days was similar in smokers and passive smokers (13.7-32.8 ng/24 h). In smokers, the amount of urinary 3-EtAde was increased >5-fold (119.3-138.5 ng/24 h) on smoking days; no effect on 3-EtAde excretion was observed on average in passive smokers (18.0-25.2 ng/24 h), The nature of the DNA-reactive agent(s) responsible for the increased urinary excretion of 3-alkyladenines, in particular of the sensitive indicator 3-EtAde, remains to be determined.