The distribution and retention of plutonium, americium and uranium in CBA/H mice

Groups of male and female CBA/H mice were given intraperitoneal injections of 40 kBq kg -1 of 239 Pu, 241 Am and 233 U citrate solutions and the retention and distribution of the three radionuclides compared at times up to 448 days. Similar results were obtained for males and females and showed that: 1 Whole body retention at 448 days was very similar for 239 Pu and 241 Am, accounting for about 20% of injected activity for each nuclide; retention of 233 U was much lower at about 3%. 2 The skeleton accounted for 85% or more of retained 239 Pu, 241 Am and 233 U activity from 6 weeks after injection. 3 The greatest concentrations of each radionuclide were measured in the main body of the spine, limb girdles and ribs, with lowest concentrations in the paw bones, head bones and caudal vertebrae. The inhomogeneity of distribution was in the order Pu>U>Am; with a trend to more uniform activity with time. 4 Average bone doses to 448 days were calculated as about 1.6 and 1.7 Gy for 239 Pu and 241 Am, respectively, and 0.3 Gy for 233 U, with ranges for individual bones of 0.7-3.0 Gy, 1.1-2.5 Gy and 0.1-0.6 Gy, respectively. Average liver doses to 448 days were calculated as about 0.9 Gy, 0.6 Gy and 0.007 Gy for 239 Pu, 241 Am and 233 U respectively, whilst the dose to the kidney for 233 U was about 0.1 Gy. 5 Autoradiographic studies of the distribution of the nuclides in the femur showed differences in their initial distribution and subsequent movement. Initially, concentrations of 239 Pu were greater on endosteal than periosteal surfaces while 241 Am distributed more evenly on bone surfaces. The initial deposition of 233 U on all surfaces was uneven with concentrations probably on active surfaces. Burial of/all three nuclides in areas of bone growth was observed. Transfer of activity to the marrow was greatest for 239 Pu and least for 233 U