Investigations of
radionuclide metabolism and effects in various mammalian species revealed important similarities between animals and humans and between some animal species. These include skeletal deposition of
radium and radiostrontium in bone volume; deposition on bone surfaces of
plutonium and other
actinides; liver deposition of
actinides; induction of skeletal or liver
malignancies by these
radionuclides; induction of tooth and
jaw abnormalities;
mammary cancer induction by
radium in humans and in the beagle; depression of circulating cells in blood; and induction of
bone fractures. There are also inter-species differences that may not have been noted if multiple species (including humans) had not been studied. Some of these are more rapid excretion of
radium in humans compared with most other mammals; induction by
radium of eye
melanomas in animals but not humans; rapid loss of deposited
plutonium from liver in many species of mice and rats but not in humans and dog; substantial sex-related differences in skeletal
plutonium retention and bone
sarcoma induction in mice but not in humans or dog; and induction of head sinus
carcinomas by 226Ra in humans but not the beagle.
Leukemia and other related
neoplasms were not induced in
radionuclide-injected lifespan dogs in excess of the occurrence in control animals. Much of our current understanding of skeletal biology and
radionuclide behavior in mammals was derived from this and related projects. The primary goal of the Utah experiment of estimating toxicities of bone-seeking
radionuclides relative to
radium has been accomplished. For 226Ra = 1.0, comparative toxicities (ratios) of a single injection for bone
tumor induction in beagles were about 16 +/- 5 for monomeric 239Pu (32 +/- 10 for chronic exposure), 6 +/- 0.8 for 241Am, 8.5 +/- 2.3 for 228Th, 6 +/- 3 for 249Cf, 4 +/- 2 for 252Cf, 6 +/- 2 for 224Ra (16 +/- 5 for 50 weekly
injections), 2 +/- 0.5 for 228Ra, and between 0.01 +/- 0.01 and 1.0 +/- 0.5 for 90Sr, depending on the dose-rate, with the lowest dose-rates approaching a ratio of zero. Corresponding ratios in mice for 226Ra = 1.0 were 16 +/- 4 for monomeric 239Pu, 5.4 +/- 2.0 for 224Ra (16 for 50 weekly
injections), 4.9 +/- 1.4 for 241Am, 5.0 +/- 1.4 for 249Cf, 2.6 +/- 0.8 for 252Cf, 4.4 +/- 1.8 for 243,244Cm and about 1.0 for 90Sr at high doses, decreasing to near zero for low doses.