Radiation dose pattern following inhalation of monodisperse and polydisperse aerosols of 241AmO2 in beagle dogs. I

Beagle dogs were exposed via inhalation to monodisperse or polydisperse aerosols of 241AmO2 to define the resultant radiation dose pattern and thus establish the relative risk in humans of inhalation of 241AmO2 and 239PuO2 or a combination thereof. Three monodisperse aerosol sizes (3.0 μm, (1.5 μm and 0.75 μm) aerodynamic diameter (AD) and one polydisperse aerosol size 1.5 μm) activity median aerodynamic diameter (AMAD) were employed to assess the role of particle size in the in vivo solubility of 241AmO2 in lung and the translocation of solubilized material in other tissues. Animals are scheduled for sacrifice at 8, 32, 64, 128, 256, 365 and 730 days after inhalation exposure with at least three animals held for later sacrifice in each particle size group. Inhalation exposures were conducted to achieve an initial lung burden of approximately equal to 0.07 μCi/kg body weight. Periodic excretion collections are being made on all animals in the study. Preliminary data are reported on the tissue distribution of 241Am measured in animals sacrificed at 64 days after inhalation exposure. Radiochemical analysis of samples obtained in this study is continuing