Experimental Respiratory Carcinogenesis in Hamsters: Environmental, Physicochemical and Biological Aspects

The respiratory tract of Syrian golden hamsters was exposed to polycyclic hydrocarbons alone and in combination with dusts. These included benzo(a)pyrene (B(a)P), silicon dioxide (SiO<sub>2</sub>), manganese dioxide (MnO<sub>2</sub>) and agar gelatin (gel), as well as dibenz(a, j)acridine (DBA) in combination with the carrier dust ferric oxide (Fe<sub>2</sub>O<sub>3</sub>). The purpose of the study was to evaluate the possible environmental hazards of these compounds and the physicochemical characteristics determining their carcinogenic activity. We also wished to study the prognostic significance of premalignant alterations in relation to treatment by carcinogenic and noncarcinogenic agents and the applicability of respiratory tumor classification in this system. When instilled alone, the dusts induced bronchial nonspecific epithelial alterations, interstitial cell proliferation and a few granulomatous changes in the lung. No respiratory tract tumors were seen. B(a)P alone induced only tracheal epithelial alterations, desquamation and metaplasia, as well as five papillomas and one squamous cell carcinoma. B(a)P in a suspension of gel