Effect of an Aqueous Extract of Cigarette-Smoke Condensate on Benzo[a]pyrene-Induced Sarcoma and Body Weight in the Rat

An aqueous extract of cigarette-smoke condensate (AECSC) prepared from a commercial brand of cigarettes was administered in 10% sugar solution as drinking fluid to Sprague-Dawley female rats for 10 weeks starting at 30 days of age. Control groups drank the same volume of sugar solution as the groups given AECSC. Animals refused concentrations of AECSC higher than 1 mg/ml and all died of dehydration and starvation. At lower concentrations, 0.125–1.0 mg/ml, weight gain was directly related to the concentration of AECSC. Doses of benzo[a]pyrene (BP) ranging from 3–400 μg, dissolved in 0.1 ml sesame oil, were given subcutaneously on alternate days for 30 doses to 30-day-old rats. AECSC (0.25 mg/ml of 5% sugar solution) or 5% sugar solution alone was given as drinking fluid. Mean tumor-induction time was accelerated in 5 of 7 groups given AECSC, but all animals given doses of 12.5, 25, 100, 200, or 400 μg BP developed sarcoma at the site of injection within 5 months. At the 3-μg dose (total dose 90 μg) all rats that drank AECSC developed sarcoma in 235 ±15 (M ± SE) days; of 19 rats that drank the sugar solution, 9 had tumors in 272 ± 19 days and 10 were free of tumor when killed at 13 months of age. Under these conditions the dose-response curve for BP lies between 0 and 12.5 μg. These observations indicate that AECSC contains one or more components which function as a cocarcinogen. AECSC did not accelerate the induction time or increase the incidence of mammary tumors in rats fed BP.