Plutonium Retention in Mice and Rats after Gastrointestinal Absorption

Abstract

The effects of oxidation state and administration medium on the retention of plutonium were studied following oral administration of plutonium to mice and rats. The weight concentration of plutonium in the solutions administered (1 x 10-'0 g/ml) was that for 239Pu at its maximum permissible concentration in drinking water, 5 pCi/ml; the administered solutions contained hexavalent and tetravalent plutonium in 0.01 M bicarbonate to simulate the compositions of treated (chlorinated) and untreated drinking water, respectively, and tetravalent plutonium in 0.01 M nitric acid and 0.17 M citrate to provide retention data that could be compared with those obtained in earlier investigations. The retention of plutonium was found to be essentially independent of its oxidation state and the medium in which it was administered. The mean of the values obtained in the mouse was 0.2% and in the rat was 0.3%. These values are two orders of magnitude higher than those obtained in earlier investigations when rats were administered 0.01 M nitric acid solutions of tetravalent plutonium. The particular significance of this difference in results is that the data obtained from the earlier investigations were basic to the establishment of a gastrointestinal absorption factor for plutonium in man, and this factor was in turn used to set the MPC for plutonium in drinking water.