Biological problems of plutonium

Toxicity of 239Pu in vivo was discussed from the aspects of its physical, chemical, and in vivo metabolic characteristics. Biological actions of 239Pu in vivo shown in literature, i.e., acute and late toxicities, and hazards of human bodies, were summarized. The proposition made by Tamplin, and arguments against it controverted by Bair et al. were discussed, and the significant problems of the controversy were as follows: 1) significance of the methodology of assessing the biological hazards, 2) shortage of radiobiological data concerning internal exposure by hot particles, 3) difficulty of exporapolating the data from experimental animals to those of human being, and 4) specificity of α-ray hazards. The maximum permissible dose would be restricted much more strictly. (Serizawa, K.)