Tumur induction by 7H-dibenzol[c,g] carbazole in the respiratory tract of Syrian hamsters.

The respiratory tract of male and female Syrian golden hamsters was treated intratracheally with 7H-dibenzo[c,g]carbazole (DBC), a tobacco smoke component. The carcinogen was given by multiple instillations at two dose levels. At the lower dose (9 mg), 35 of 46 hamsters (72%) developed respiratory tract tumors. The group receiving treatment at the higher dose level (30 mg) died earlier because of the toxicity of the compound. In this group, 15 of 45 animals (33%) had respiratory tract tumors. These occurred in the larynx, trachea, bronchi, and lungs, but predominated in the trachea and bronchi. Morphologically, most tumors were papillomas and squamous cell carcinomas. This study indicates the highly potent carcinogenic effect of DBC and that respiratory tumors can be induced in this model system without any carrier dust.