44 VIII. PLUTONIUM Summary Plutontum-239 is a man-made alpha emitter with a 25,000 yr half life. For plutonium that reaches the blood, its target organs are bone and liver. Inhaled plutonium may affect the lung as well. Plutonium is an efficient carcinogen. ~ The metabolism of plutonium and its production of bone tumors were inves- tigated in the 1940s. More elaborate and sophisticated studies on the biological significance were begun in the 1950s and 1960s and continue. Its effects on bone, liver, and Tung have been demonstrated in a number of laboratory animal species. Environmental Pathways “oc Most of the information on plutonium in the environment that evolved during the 1940s was related to monitoring environmental materials near nuclear installations (Stannard, 1973a). These investigations were centered primarily on aquatic envirorments and biota. . ir 1945 Trinity shot several years after that detonation. assumed to be plutonium-239 (Olafson and Larson, 1963). The activity was By 1950, plutonium released to the environment from atomic weapons testing was recognized as tions of hazards fron world-wide contamination by plutonium were also made : vo : - os ee ee a renee ree vetinarian : ‘ presenting a serious potential for tnjury if inhaled or ingested, and calcula- . 2 Oe RR g a at = ., Pal. Alpha activity was found in animals trapped in the fallout zone of the (Glasstone et al., 1950). Oogs and sheep intentionally exposed to the radio- active fallout fran weapons tests in 195] were found to have 239Py in their Tungs (Smith et al., 1952).