The metabolism of curium in the rat.

This isotope of curium is radioactive and decays by the emission of an a-particle to form Pu2% which, in turn, is also radioactive. Cm242 has a half life of 150 days and its radioactive daughter, PUCK, has a half life of 50 years. This isotope of plutonium decays by the emission of an a-particle to form U234 which has a half life of 233,000 years. Shortly after the organization of the Atomic Energy Project, it became apparent that formidable problems would be presented as the result of the release of nuclear energy. One of the most urgent of these was the hazard presented by the production of large quantities of the radioelements created by the fission of uranium and the coincidental formation of neptunium and plutonium. In an attempt to evaluate the potential danger presented by these radioelements from the chain-reacting pile, a large series of metabolic studies with experimental animals was undertaken in a number of laboratories working upon the atomic energy program. These studies, which have been briefly summarized elsewhere (2), included a series of investigations on the metabolism in the rat of the more important members of the fission products,in the carrier-free state, as well as most of the heaviest elements at the end of the periodic table. These studies made it possible to predict on a semiquantitative basis the potential hazards that this large number of radioactive elements might present should they gain entry into the body. Recently a description of the metabolism of americium has been reported in considerable detail (3). This element immediately precedes curium in