body burden means for adults on Utirik and the observed Kp rate constant from Rongelap. It was observed on Rongelap that .031% of 6520 was removed from the diet pathway each day in addition to radioactive decay. Additionally, reduction : . . wo 137 90 60 in dietary radioactivity on Rongelap had been observed for Cs, Sr, and Co to be greater than that predicted by radioactive decay alone. Instantaneous re- duction fractions very similar to those at Rongelap were observed at Utirik for the 90 Sr, and 137 Cs — nuclides. . The lower curve on Figure 16 reflects the dose equivalent, dose equivalent rate, and body burden which would have occurred had . . 6 oo . radioactive decay alone accounted for the removal of >on from the Utirik environment. Since additional mechanisms could be measured for other nuclides at Utirik and for the 6575 nuclide on a nearby atoll, the upper curve was chosen as themost likely body burden history for adults post return to Utirik Atoll. Figure 17 indicates the Utirik adult mean total body dose equivalent rate for each nuclide. An obvious difference relative to the Rongelap history exists; 6575 not 1376. was the major nuclide contributing to the dose equivalent rate. This was due to the Utirik population returning 3 to 4 months after the initial contaminating event, and the Rongelap population returning after 3 years. The age of the fallout had a dramatic influence on the importance of each nuclide contributing to the internal dose equivalent. In fact 606, and on played major roles during the first 3 years, a time interval that corresponded to the period during which field whole body counting facilities were being developed at Brookhaven National Laboratory and when medical examina-~ tions for people on Utirik Atoll were not done. Additionally, pooled and/or in- dividual radiochemical analysis of urine was not performed during this period. . 6 . : The impact of 52m and 606, was such that even if the least conservative rate 34