Differences in the radiotoxicity of two plutonium isotopes in cells in vitro: can they be ascribed to different handling by the cells?

Exposure of Co631 cells to plutonium leads to increasing cell death depending on the dose and incubation time. The effects, however, are more pronounced with 239Pu, than with 238Pu. Uptake and binding of the two radionuclides during a 5-h incubation are about equal, but 238Pu is lost more rapidly from the cell. There are also differences in the subcellular distribution which lead to a pronounced difference in the distribution of radioactivity. The influence of these differences in the handling of 238Pu and 239Pu by the cell and of the mass difference on the radiotoxicity of the radionuclides is discussed.