of Goats that received curium intravenously retained approximately 64 percent the injected dose at time of sacrifice (Table 4). As noted in the table, nearly half of this retained curium was found in the liver. On both a percentage of dose per organ and a percentage of dose per kilogram basis, liver, bone, and kidney had consistently high curium values. The thyroid gland also Individual curium concentrahad readily detectable curium-243 concentrations. tions for bile are probably of doubtful significance since several variables However, a large part of the fecal curium affect the volume of bile produced. (for the I.V. dosed goats) was probably transported to the gastrointestinal The total curium output in the feces of the three intratract by the bile. venously injected goats averaged 4.5 percent of the administered dose. Curium concentrations in the tissues taken from the orally dosed animals were of course much lower than the concentrations noted in the intravenously exposed Liver, bone, and goats, but the basic distribution pattern was similar. kidney retained the highest concentrations of curium on a percentage of dose per kilogram basis. However, the above-mentioned organs plus cardiac muscle were the only tissues from the orally dosed group to consistently have detectable Furthermore, the total amount of curium-243 retained in amounts of curium. all tissues collected from any individual goat did not exceed 0.01 percent of the original oral dose. Previously acquired information on the biological transport of plutonium following a 50 uCi acute intravenous injection of citrate-buffered plutonium-238 nitrate to one lactating goat is presented in Table 5 (Stanley and Mullen, 1971). The two groups of data, expressed as a percentage of administered dose per kilogram of milk, urine, or feces, are not strictly comparable. Plutonium data are based on a single goat, while the curium results shown represent an average of the three goats used in this study. There were also slight differences in dosing and collection schedules, and no comparison has been included for the detection efficiency of the analytical techniques. Nonetheless, this information does provide an opportunity for a gross comparison between the physiological transport of plutonium and curium in the same ruminant species under somewhat similar conditions. Curium was excreted more rapidly than plutonium in the first week post-injection. Shortly after injection, the percentage of administered dose per kilogram of milk and urine was noticeably higher for curium (Table 5). On this percentage of dose per kilogram basis, curium values remained consistently greater than plutonium values in most milk, urine, and fecal collections. This relationship between curium and plutonium was also evident on a total excretion basis. The total amount of curium transported to the milk and urine by 144 hours post-injection was 2.2 and 4.6 percent of dose, respectively. Total plutonium transport to milk and urine over this 144-hour period was 0.8 and 1.8 percent of the administered dose. 174