Composition Studies on Tobacco. XLIV. Tumor-Promoting Activity of Subfractions of the Weak Acid Fraction of Cigarette Smoke Condensate<xref ref-type="fn" rid="FN2">2</xref>

Subfractions of the weak acid fraction of cigarette smoke condensate (CSC) were tested for tumorigenic activity in mice previously painted with 125 μg 7,12-dimethylbenz[a]anthracene (DMBA). In one experiment, the pH of the test solutions ranged from 5.7–6.0. In a second experiment, the pH range was 5.0–5.5. Before fractionation the weak acids were more active in the second experiment with the lower pH. The residue remaining after steam distillation was consistently active. The steam distillates and a synthetic steam distillate gave inconsistent results and probably do not contribute importantly to the carcinogenicity of CSC for mouse skin. In high concentrations, the unfractionated weak acids produced 2 tumors in a group of 50 mice that had not been previously exposed to DMBA. The weak acid fraction is thus a very weak complete carcinogen. Even so, a comparison of the tumor yields produced by DMBA alone, by the weak acids alone, and by combinations of both agents suggests that the weak acids acted as promoting agents. It was concluded that the promoting activity of the weak acid fraction of CSC depended primarily on the nonvolatile constituents and only slightly on volatile phenols and other constituents of the steam distillate.