Abstract
Female F-344 rats, (50 animals) received intragastric administration of N-nitrosoheptamethyleneimine (NHMI) 3 times a week, for 10 weeks. The cumulative doses were 150, 300 or 600 mg/kg body weight. Various types of tumors developed in the nasal mucosa, trachea, lung and/or esophagus. In the lowest dose group, no malignant tumor was observed. Lung adenomas were common but few tumors developed in the nasal mucosa, trachea or esophagus. In the other two groups, malignant tumors were common. The histological types of tumors in the two groups differed slightly, especially in the nasal mucosa. Neuroblastoma were popular in 300 mg/kg group but squamous cell carcinomas were more common in the highest dose group. Only 1 tracheal tumor was observed in this experiment.
The relationship of cumulative doses of NHMI to the types of tumor and target organs was reported. The influence of the administration schedule on carcinogenicity was also discussed in comparison with the previous findings of Taylor and one of the authors (P.N.)
