Inhalation Toxicology of${}^{238}{\rm PuO}{}_{2}$ and²³⁹ PuO₂ in Syrian Golden Hamsters

Male and female, young adult, Syrian golden hamsters were exposed to high-fired, freshly prepared, aerosols of${}^{238}{\rm PuO}{}_{2}$ or²³⁹ PuO₂. Initial alveolar depositions of plutonium ranged from about 3 to 200 nCi. The fate of inhaled PuO₂ in the hamster was similar to that previously described in the rat. Only in male hamsters exposed to large amounts of²³⁹ PuO₂ was there significant shortening of life span. The incidence of adenomatous metaplasia in the lung was as high as 16% in unexposed controls and increased with increasing radiation dose to a maximum of 58% at the highest deposition of plutonium. Only three hamsters developed malignant tumors in the lung, all adenocarcinomas, and all at initial alveolar depositions > 160 nCi. It was concluded that the hamster was resistant to the induction of lung tumors following inhalation of insoluble particles containing α-emitting radionuclides.