INDUCTION OF PULMONARY TUMOURS IN MICE BY MITROSONORNICOTINE, A POSSIBLE CONSTITUENT OF TOBACCO SMOKE.

Abstract

NITROSAMINES could be formed in cigarette smoke by reactions between secondary amines and oxides of nitrogen1,2. Several secondary amines, including anabasine, nornicotine, dimethylamine, diethylamine, pyrrolidine, piperidine and proline, have been detected in cigarette smoke, which also contains about 200 parts per million of oxides of nitrogen (as the sum of NO and NO2) (refs. 3 and 4). The nitrosamine derivatives of some of these amines have already been shown to be carcinogenic5,6. We have reported that nitrosoanabasine administered in the drinking water induced benign and malignant tumours of the œsophagus of rats1. In parallel with these biological investigations, attempts have been made to detect nitrosoanabasine and nitrosonornicotine in cigarette smoke. So far these attempts have not been successful, although methods capable of detecting small amounts (for example, 5 µg) of specific nitrosamines have been developed1. Lack of success may be due either to instability of nitrosamines under the conditions prevailing in cigarette smoke or to interference in their detection by other constituents of the smoke. Nitrosoanabasine could not be detected in cigarette smoke condensates to which it had been deliberately added nor in the smoke of cigarettes which had been impregnated with the substance before smoking. If these negative results are due to instability of the nitrosamines, the possibility of their biological importance is only ruled out if their half-lives are very short. Further investigations into these problems are in progress.