Carcinogenicity of Benzo(a)pyrene and dusts in the hamster lung (instilled intratracheally with titanium oxide, aluminum oxide, carbon and ferric oxide).

The possible carcinogenic or fibrogenic effects of intratracheal instillation of a polycyclic hydrocarbon, benzo(a) pyrene (B(a)P), alone or in combination with several dusts - titanium dioxide (TiO2), aluminum oxide (Al2O3), carbon (C), and ferric oxide (Fe3O3) - were investigated in hamsters. When administered alone, the dusts induced interstitial cell proliferation, bronchial epithelial alterations and a few granulomatous changes in the pulmonary system, but no tumors. B(a)P alone induced only two tracheal papillomas. However, combined treatment with B(a)P and the dusts caused a number of tumors, dependent upon the dust used. B(a)P plus TiO2 in a small particle size (below 0.5mu) induced papillomas, squamous cell carcinomas and a few adenomas and adenocarcinomas of the larynx, trachea and lungs. These were morpholoigcally similar to neoplasms found after B(a)P and Fe2O3 treatment. B(a)P, combined with C or Al2O3, induced mainly laryngeal and tracheal papillomas. B(a)P- and C-treated hamsters also showed a few lung adenocarcinomas.