Mammals actinides

The uptake of plutonium by bone has received considerable attention as irradiation of bone marrow has been associated with leukaemia-type diseases. As Durbin (192) has observed the uptake of plutonium into mineralised material is not restricted to mammals but can occur in any creature, invertebrate or vertebrate, which contains calcium phosphate or calcium carbonate structures. It can be expected that the trivalent actinides will also deposit in similar material. 

Field Studies. We have attempted to compare the relative availability of actinides to small mammals living in contaminated environments near ORNL. Shrews, rats and mice have been collected from a 30 year old contaminated floodplain forest ecosystem ( ). Cotton rats (Sigmodon hispidus) have been collected from the banks of a former liquid radioactive waste pond which contains Pu, Am and Cu in sediments and shoreline vegetation. Analyses were performed by isotope dilution mass spectrometry (U, Th and Pu) or by alpha spectrometry (Pu, Am and Cm). 

Figure 4. Comparative accumulation of actinides by small mammals from contaminated soil or sediment relative to the accumulation of plutonium-239. Accumulation factor (AF) = concentration of nuclide in the internal small mammal body -- concentration of nuclide in dry soil. Twelve shrews and seven rats and mice from a floodplain forest were composited to yield four and three separate analyses, respectively. Twelve cotton rats inhabiting the banks of a liquid waste pond (3513) also were analyzed.

Table VI. The accumulation of actinides by small mammals and man from soil expressed as the concentration ratio of element in...

From the calculated bone/soil ratios in man for the naturally-occurring actinides as well as the laboratory and field studies on small mammals, the availability of Pu, Am, and Cm relative to U and Th can be deduced. First, the field studies indicate a similar degree of uptake by mammals for Pu and Th (Fig. 4, Table VI) which are both characterized by the tetravalent state in the terrestrial environment (20). Second, the trivalent actinides. Am and Cm, tend to exhibit similar (Fig. 3) or slightly greater (Fig. 4) uptake by mammals than Pu. Last, U exhibits consistently greater uptake in mammals than Th or Pu (Fig. 4, Table VI). On the basis of available data, the following rank order of bone ash/soil ratios for... 

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