Carcinogenicity of Different Polycyclic Hydrocarbons in the Respiratory Tract of Hamsters

Summary

The respiratory tracts of male Syrian hamsters were exposed to different polycyclic hydrocarbons: benz [a]anthracene, [benzo[b]fluoranthene, dibenz[a,h]-anthracene, dibenzoa,i]pyrene (DB[a,i]P), and pyrene. The carcinogens were given by multiple intratracheal instillations at two dose levels with an equal amount of ferric oxide in saline. Except for DB [a,i]P, most compounds were not carcinogenic in the respiratory tract at the dose levels given. Both groups that received DB[a,i]P had a high incidence of carcinomas. In the hamsters treated with the lower dose (8 mg), 16 of 34 (47%) developed respiratory tract tumors, and in those receiving the higher dose (12 mg), 39 of 44 (89%) developed respiratory tract tumors. In the latter group, more than 50% of the tumors were squamous cell carcinomas, with the first tumor seen at the 27th week. Most tumors in both groups arose from the epithelium of the bronchi and trachea. The present results demonstrate that DB[a,i]P is a more potent carcinogen in the respiratory tract than benzo[a]pyrene. The other carcinogens, effective in other organs such as skin, showed little effect in the respiratory tract.