Carcinogenic and Cocarcinogenic Effects of Inhaled Synthetic Smog and Ferric Oxide Particles

Abstract

The carcinogenic and cocarcinogenic activity of synthetic smog, ferric oxide (Fe₂O₃) dust, and a mixture of the two air contaminants was determined in a long-term inhalation study with Syrian hamsters. Inhaled Fe₂O₃ particles definitely enhanced diethylnitrosamine tumorigenicity in the peripheral lung. Synthetic smog did not. When tested at a concentration of 40 ppm methane equivalents or 40 mg/m³, respectively, neither air pollutant by itself appeared carcinogenic. Fe₂O₃ caused pulmonary fibrosis and synthetic smog caused alveolar bronchiolization in many of the exposed animals.