ee et get INTERNAL DEPOSITION OF RADIONUCLIDES and the analysis at 4 months represents only radiological decay, Thus, the results are not directly comparable to those obtained from animals which were returned alive, and in which biological turnover as well as radiological decay were operating. | The largest fraction of the gross beta activity in the fish was contributed by the concentration of radioactive inaterin] in the viscera. In two of the fish in which bones and muscle were separated and analysed, equal amounts of activity were found jin each fraction. Wowever, the storage of these fish in formaldehyde for 3 months may have permitted the diffusion of the radioelements from bone to muscle to take place. Furtherstudies on fresh fish will clarify this point. The contamination of the Ash in the lagoon was considerably greater than that of the Jand aniinals studied. As fish form a Jarwe staple item in the diet of the Marshallese, the high level of contamination is important. At the end of a 214-month experimental period, the excretion by the chickens of both beta and gammaactivity per 24+ hours was 5 percent of the value measured at the start at 37 days post detonation (Fig. 5.1). -Analysis of pig excreta indicated a decrease of activity with time. In a period, the gamma activity excreted hours decreased to about 2.5 percent of similar G-week per 24 the ac- tivity excreted at 44 days post detonation, The excreta of the pigs from Utirik contained less than 10 percent of the gross beta activity found in the excreta of the pigs from Rongelap at thesame time. This ratio of 10 was approximately the same ratio found between the activity of the food, water andsoil samples of the two locations. Radiochemical Analysts of Tissues and Fxereta, Radiochemical analysis of pig tissues indicated that 62 percent of the skeletal beta activity was derived from Sr", 7 percent from I3a**, and 10 percent from the rare earth group at 82 days post detonation (Table 5,8). The radioisotopic composition of the urine at this time wassimilar to that of the skeleton. ‘The distribution of activity in the body of the pig 900218b §1 nay representthe distribution in human beings. The absolute amount of internal contamination ‘in the Rongelap people was, however, only 2 tenth of that found in the animals. At 4 months post detonation, the alkaline earths comprisedless than 2 percent of the total activity in the clam (Table 5.10). The rare earth group constituted 33 percent of the total beta activity. The balance of the activity was contributed chiefly by Zr (21 percent) and Rus (32 percent). About 40 percent of the material found in the viscera of the fish was of the rare earth group. Very smal] amounts of strontium and barium were found. In the tissues of the fish, strontium, barium and the rare earths contributed only abort 10 percent uf the total activity. 5.43. Autoradiographs A number of autoradiographs of the tibine and femurs of 1 chick, 4 pigs. I rooster and 2 chickens were prepared both at the TSNRDI. and at the Argonne National Laboratory (ANJ.) to determine the pattern of deposition of fission products. Contact printing on A-ray no-screen film was found to be the most satisfactory method of preparing, the autoradio- eraphs. The discussion and conclusions pre-| sented below summarize the findings reported by Norris (15). The autoradiograph of a tibia from a chicken sacrificed at 45 days post detonation (Fig. 4.2) indicated a relatively uniform distribution of the activity throughout most of the bone, with the highest concentration of activityin the area adjacent to the epiphysis. This area of high activity corresponds to an area of dense, trabecular bone. The tibia and femur of a baby clfick, which died spontaneously 47 days post detonation, showed the heaviest concentration of radioactive material in the diaphysis (Fjg. 3.3). The end regions of the bone, which were laid down after the animals were removed from the contaminated environment, were relatively lacking inactivity. The region of ereatest activity was in the diaphysis, which appeared to be ab-