Toxicity of inhaled polydisperse or monodisperse aerosols of 241AmO2 in Syrian hamsters. III

To obtain a better understanding of dose-response relationships for inhaled 241Am, Syrian hamsters were exposed by inhalation to monodisperse or polydisperse aerosols of 241AmO2. The animals were exposed to achieve graded initial lung burdens of 240, 60, 15, 3.8, 0.95, 0.24 and 0.029 nCi 241Am for the polydisperse aerosol and 240, 60, 15 and 3.8 nCi 241Am for each of the three sizes of monodisperse used (0.8, 1.3 μm AD). In addition to animals exposed for life span observations, other animals were exposed at the same time for serial sacrifice to study patterns of radiaton dose. All animals have now died and preliminary data are available on lung, liver, and skeleton retention through 500 days after exposure. Significant life span shortening was observed in groups of animals receiving initial lung burdens of greater than 110 nCi 241Am for the polydisperse aerosol. Histopathologic examination of tissues taken at necropsy is continuing. No pulmonary neoplasms have been observed to date