The gastrointestinal absorption of plutonium and americium in the hamster.

Plutonium-239 and americium-241 were administered to adult hamsters in various chemical forms and their absorption from the gut was measured. The results have been compared with published data on other species in order to derive values for the estimated absorption of these actinides in man. On the basis of current knowledge, the best values for adults would appear to be: 0.05% for americium, 0.01% for plutonium ingested in soluble form, and 0.0001% for plutonium ingested as the dioxide. Plutonium dioxide should be considered as soluble if a significant proportion (greater than 5%) of the activity is in particles less than 25 nm in diameter.