Morphology and sex-dependent manifestation of nasal tumors in B6C3F1 mice after chronic inhalation of 1,2-dibromo-3-chloropropane.

Groups of 50 B6C3F1 mice of each sex were exposed to air containing of 1,2-dibromo-3-chloropropane at concentrations of 0.6 or 3.0 ppm for 6 hours per day, 5 days per week for 103 weeks. Untreated controls consisted of 50 mice of each sex. All surviving animals were killed at 104 weeks. Adenomas, squamous cell papillomas, adenocarcinomas, squamous cell carcinomas, carcinosarcomas, fibrosarcomas, and hemangiosarcomas of the nasal cavity occurred in male and female mice with dose related trends. Eighty-seven percent of the high dose female mice had nearly twice as many tumors as the high dose males (47%). Fourtynine percent of malignant neoplasms of the high dose female mice infiltrated the brain or metastasized to the lungs. Whereas two animals (4%) of the low dose female mice showed infiltrating carcinomas, no male mice exhibited this feature.