<500 <1,000 <5,000 <20,000 pci/kg pCi/kg pCi/kg pCi/kg - reticulum sediment rumen fluid rumen vegetation skin and hair 100 As shown in Figure L (from Smith et al., 1976c), the plutontum-239/plutonium-738 ratios in the tissues of sacrificed cattle were generally less than the ratio of 42 observed in ingesta from fistulated steers grazing the inner compound of Area 13, which tends to support the hypothesis that plutonium-238 is more readily assimilated. A plutonium-239 retention factor of 0.00056% for bone + muscle + liver was calculated on the basis of ingesta activities (Smith et al., 1976c). This factor was verified by two different statistical approaches by other investigators (Gilbert et al., 1976). As shown in Table 2, other animals sampled from the study area included two goats, three foxes, one coyote, and a jackrabbit. Data from the tissues of these animals indicate that levels in most of the tissues fell within the same Tanges as from the cattle. However, concentrations were higher in the muscle of the goat and in the muscle, liver, and kidney tissues of the predators. The collection of soil sediments from the ingesta of both fistulated steers and from a sacrificed cow indicated that less than 0.5 kg of soil was ingested daily. The last animals grazing the Area 13 range were sacrificed, necropsied, and sampled in January and March of 1976. When available, the data from these animals should allow a more definitive comparison of levels found in nearly identical animals (two cow-calf pairs) who spent their entire lives within two contaminated environments of different magnitude. Of intense interest also are data from the gonads of animals (male and female) bred and bom within the study area. Additional data will be available on the placenta transfer of actinides, Tissues from the last of the original cows will furnish information as to whether the actinide tissue levels have reached equilibrium within the j-year grazing period. N -- 2id1XYAS N < | It was found that actinides crossed the placental barrier and were deposited in fetal tissue at nearly the same levels as found in the dam's corresponding tissues. Actinide concentrations in the gonads (both male and female) were greater than that found in most other soft tissues, e,g., the median plutonium-239 value in the gonads was approximately 25 times greater than that of muscle (Smith, 1976b). As shown in Figures 2 and 3, similar relationships were found in tissues from cattle grazing near the Rocky Flats plant in Colorado (Smith and Black, 1975), While it must be remembered that the data base from both of these herds is small, the data do tend to support the work of others who have noted higher gonadal concentrations in other species (Takizawa, 1973; Krey and Bogen, 1962; Morrow et al., 1967). Other workers have noted insignificant gonadal concentration (Richmond and Thomas, 1974). Perhaps a more definite trend may be apparent when the analytical data from gonads of the 1976 Area 13 cattle become available, : ae 2 . | | \ \ $5 \ N a N A \ So \ N 1x NN | 0.1 BEN - - RATIO IN INGESTA BONE LUNG LIVER MUSCLE AREA 13 CATTLE MJ NTS CATTLEN Fig. 1. Ranges of cattle. 2395, /238 Pu ratio in tissue from Area 13 vs. NTS 4ll