Comparative stochastic effects of inhaled alpha- and beta-particle-emitting radionuclides in beagle dogs

The stochastic effects of inhaled, insoluble particles of alpha- or beta-pa rticle-emitting radionuclides were compared in dogs. Male and female beagle dogs were exposed briefly by nasal inhalation to relatively insoluble aero sols of (PUO2)-P-239 or Ce-144 in fused aluminosilicate particles (FAP) and observed for cancer for their lifetimes. The initial lung burden and reten tion of each radionuclide was determined by whole-body counting of the emis sions from Ce-144-Pr-144- or Yb-169-labeled (PuO2)-Pu-239. Lung doses were calculated for each dog from these data. The lung doses ranged from 0.21 to 1200 Gy for Ce-144 FAP and 1.6 to 58 Gy for (PUO2)-P-239. Dogs With doses to the lung of about 60 Gy or greater from Ce-144 or about 2 Gy or greater from (PUO2)-P-239 had an increased incidence of lung carcinomas. In dogs ex posed to Ce-144 FAP, three organs were targets for neoplasia: lung, tracheo bronchial lymph nodes, and heart. The insoluble FAP carried to the lymph no des draining the lung delivered high radiation doses to the nodes and adjac ent heart, resulting in hemangiosarcomas of these organs. In the lung, high radiation doses induced hemangiosarcomas and carcinosarcomas. At lower dos es, carcinomas of various histological patterns were induced in the lung. I n dogs exposed to (PuO2)-Pu-239, the lung was the sole target organ for neo plasia. Nearly all of these neoplasms were carcinomas of various histologic al patterns. These results indicated that relatively low doses of alpha-par ticle radiation can induce pulmonary cancers, but relatively large doses of beta-particle radiation are required. In addition, inhaled beta-particle e mitters can also induce cancers in lung-associated lymph nodes and heart at these larger absorbed radiation doses. (C) 1999 by Radiation Research Soci ety.