Synergistic effects of diethylnitrosamine and different dusts on respiratory carcinogenesis in hamsters.

A possible synergistic action between the carcinogen diethylnitrosamine injected s.c. and MgO, A12O3, or carbon instilled intratracheally in the respiratory tract of Syrian golden hamsters was studied. Diethylnitrosamine alone induced tumors of the nasal cavity in 50% of the animals. Tumors were also produced in the larynx and trachea but not in the lungs. Groups receiving weekly intratracheal instillations of 0.9% NaCl solution suspen sions of carbon or A12O3 had no tumors of the respiratory system. MgO alone induced a significantly large number of lymphomas of the histiocytic type that were not induced by diethylnitrosamine and MgO. In the groups receiving diethylnitrosamine followed by intratracheal instillations of dust-0.9% NaCl solution suspensions, the tumor incidence in the upper respiratory tract was similar to that seen with diethynitrosamine alone, but lung tumors were also ob served. Intratracheal instillations of 0.9% NaCl solution after diethylnitrosamine also caused a number of tumors to occur in the lower respiratory tract. It can be concluded that carbon and A12O3 are not carcinogens for the respiratory system of hamsters. The increase in incidence of lower respiratory tract tumors previously seen with diethylnitrosamine followed by Fe2O3 and 0.9% NaCl solution was here obtained with diethylni trosamine followed by 0.9% NaCl solution alone.