Mouse skin assay of condensate from smoking products other than tobacco.

The biologic activity of a smoking product other than tobacco (Cytrel) was compaed with that of an American-type blend of cigarette tobaccos by application of the smoke condensate (SC) to shaved mouse skin. In 4 nonsimultaneous experiments, SC's from the former were equivalent or lower in tumorigenicity than equal doses of those from the latter, studied simultaneously and under identical conditions; this was true for widely varying doses of SC's, ranging from 35 to 246 mg nonaqueous condensate (NAC) administered to each mouse/week for 63-92 weeks. The response to SC from smoking products other than tobacco ranged from a complete lack of epidermoid carcinomas and papillomas at the lower doses to an incidence of lesions in 25.3% of the animals at the highest dose. The SC from a typical American blend of tobaccos caused skin lesions in 18.7-39.1% of the animals. SC from type 324 Cytrel, applied at the even higher dose of 365 mg/mouse/week, caused papillomas or carcinomas in only 22.0% of the animals, as compared with 39.1% of mice after adminstration of 245 mg SC from the American blend of cigarette tobacco; this was the highest dose that could be achieved with a test material containing nicotine. SC from a 1:1 blend of Cytrel with cigarette tobacco produced considerably fewer skin lesions at the lower dose levels than did SC from tobacco. At the lowest dose of 35 mg/mouse/week, 2 and 18.7% of the animals had lesions, and at a 54-mg dose, 11.3 and 22.7% had lesions from the blend and tobacco samples, respectively. At an increased level (113 mg), the response was the same for the SC from a 1:1 blend and from cigarette tobacco. There existed an excellent dose-response relationship for SC from type 308 Cytrel tested at four dose levels: 8.4, 113, 246, and 383 mg NAC/mouse/week, with 0, 18.7, 25.3, and 57.7% of the animals exhibiting skin lesions, respectively. Based on the criteria inherent in the technique of "mouse skin painting", Cytrel variants appeared to be lower or equal in tumorigenicity than did cigarette tobacco.