Se een ox be [ i ” Fig. 5.4 Autoradiograph of Rongelap Pig Tibia, 42 hr Exposure. Animal!Sacrificed 58 Days Post -exposurce. : _— . ~t ‘ 5.4 HUMANSTUDIES 5.4.1 Excretion Gross beta activity measurements on the urine samples from Rongelap, Ailinginae, and Rongerik indicate significant contamination in the majority of samples. The variation in beta activily excreted, 24 hours among individuals in any one group is quite large (Table 5.1). If the mean values of urine activity of the adults of the three groups six weeks after exposure are compared, it will be seen that the Rongelap group had the highest activity, 1208 d m 24 hours. The Aijlinginae group had 553 d/m/24 hours, and the American group had 309 d, m 24 hours. A group of the Japanese fishermen exposed to fallout from the same detonation had a urine activity comparable to that of the Rongelap adult group. The mein activily of the individuals under 15 years of age appears to be considerably Jower than that of the adult group. An examination of the group collections analyzed by the various Liboratories involved showed fairly consistent levels of activity for the individual from day to day. The variation which occurs is not considered to be excessively lirge for this type of study. The activity as function of time fell off rapidly due to the large component of Ba'4® -. pa" and other shert lived radioisotopes. For example the Rongelap group had a mean activity of 1208 d/m,24 hours at 46 days and activity of 339 d/m/24 hours at 90 days. At six months post-exposure the Rongelap urine was found to contain a barely detectable amount of beta activity. The results of radiochemical studies of urine indicate that Sr®, Ba", and the rare earth group apparently constitute 77 per cent of the total beta activity at 46 days. Stran- tium-89 contributes 40 per cent of the total beta activity, Ba'“?—11 per cent and the rare earta teen reecoe . » arpeee 92 So eer gy rey wy ‘4 eer , .