BIOLOGICAL TRANSPORT OF CURIUM-243 IN LACTATING DAIRY GOATS W. W. Sutton, R. G. Patzer, Pp. B. Hahn, and G. D. Potter Environmental Protection Agency Environmental Monitoring and Support Laboratory, Las Vegas ABSTRACT Six lactating dairy goats (average weight 43.5 kg) were given either intravenous Three animals each received a single or oral doses of curium-243 chloride. 20.8-pCi intravenous citrate-buffered injection and the remaining three goats Milk, urine, fecal, and were given a single oral dose of 200 wCi per animal. blood samples were collected daily over a 144-hour period after dosing and the animals were sacrificed approximately 162 hours post-treatment. tissues were collected and analyzed for curium content. Selected Curium concentrations in the sample material were determined by counting the 228-keV and the 278-keV gamma rays of curium-243 using a NalI(Tl) detector and pulse height analyzer. Analytical results to date have shown that at least 99 percent of the oral dose was excreted in the feces with low to nondetectable concentrations in the milk and tissues. However, approximately 2 percent of the intravenous dose was transferred to milk during the 144-hour collection period. The average transfer to urine and feces in these injected goats was 4.6 and 4.5 percent of the administered dose, respectively. Curium retention in the tissues collected for analysis totaled approximately 64 percent of the injected dose, with essentially half of this retained curium found in the liver. Comparisons between the transport of plutonium and curium in dairy goats are discussed. INTRODUCTION An increased research and development effort is currently being directed toward the use of radiofissionable fuels as power sources. Current projections of future energy requirements suggest that isotopes of uranium and plutonium 167