Nasal Carcinomas in Beagles After Inhalation of Relatively Soluble Forms of Beta-Emitting Radionuclides

Beagles were exposed by inhalation to relatively soluble forms of single beta-emitting radionuclides and are being held for life-span observation to evaluate biologic hazards associated with nuclear power production. The dogs were exposed to graded activity levels of 91YCl3, 144CeCl3, or 90SrCl2. With 91YCl3 and 144CeCl3, a significant radiation dose was delivered to the respiratory tract, liver, and skeleton. With 90SrCl2, the dose was almost totally to the skeleton. Squamous cell carcinomas associated with the nasal cavity have been the most frequently observed neoplasms in the 91YCl3 study and one of the most frequent in the 144CeCl3 study, whereas few squamous cell carcinomas have been seen in the 90SrCl2 study. One hemangiosarcoma in the nasal cavity was also seen in the 144Ce study. The incidence of nasal cardnomas may be related to higher relative concentrations of the radionuclides 91Y and 144Ce associated with the nasal turbinates. This relatively high risk of nasal cavity neoplasms suggests that standards for human expolure to these radionuclides should include a consideratlon of the nasal cavity epithelium as a major target tissue.