Occurrence of hemangiosarcomas in beagles with internally deposited radionuclides

In a series of related experiments to evaluate the relative toxicity of inhaled radionuclides, beagles were exposed to aerosols containing relatively soluble (chloride) or relatively insoluble (fused clay) forms of 144Ce and 90Sr. With the soluble 144CeCl3, significant radiation doses were delivered in the lungs, liver, and skeleton whereas, after 90SrCl2 exposure, the radiation dose was delivered predominantly to the skeleton. In dogs exposed to 144Ce and 90Sr in fused clay particles, radiation doses were delivered mostly to the lungs and tracheobronchial lymph nodes. In most dogs dying within 2 years after exposure, deaths were attributable to nonneoplastic radiation-induced lesions in the target organ systems. At later times after exposure, neoplasms were the major cause of death, again occurring mostly in target organs or the adjacent tissues. Lung, liver, and bone-related neoplasms, including five hepatic hemangiosarcomas, developed after 144CeCl3 exposure. Among the bone-related sarcomas seen in dogs exposed to 144CeCl3 or 90SrCl2, the incidence of hemangiosarcomas was over 40 percent. Among the 20 dogs dying with pulmonary neoplasms after exposure to 144Ce or 90Sr in fused clay particles, all had hemangiosarcomas and several also had other neoplasms. This high incidence of hemangiosarcomas has occurred within 7 years after exposure and differs from results in other laboratories where beagles have been exposed to both α- and β-emitting radionuclides