Radiopathology of Americium 241: I. Distribution of Americium in Adult Mice

I. Distribution of americium in adult mice LARS HAMMARSTR~~M and AGNAR NILSSON 'Hie increasing production and use of transuranic elements have enhanced the interest in their relative toxicities, metabolic behaviour and carcinogenic properties.At present the maximum permissible levels for transuranic elements are based on the assumption that their biologic risks are similar to those of plutonium; however, this does not always seem to be true.A comparison of the uptake of "'"Am and 2:i0Pu in the skeleton of rats indicated that the initial uptake of "'"Pu in the skeleton was about 1.4 times greater than that of '*lAm, while the rate of loss from the skeleton was almost the same for these nuclides.The rate of excretion from the body was higher for "'Am than for "'Pu and the retention of the latter in the liver was of a longer duration than that of 241Am (TAYLOR et coll.1961).Differences also exist in terms of biglogic effects.BENSTED et coll.( 1965)have proved that 77 '/c (17/22) of rats given 3.0 '"Pu/kg body weight developed bone tumours.I n addition, one case of renal carcinoma and one of myelogenous leukemia were observed.After the injection of 2.5 ,uCi 241Am/kg body weight This work was supported by the Swedish Medical Research Council Grant No.