body-burden means for adults on Utirik and the observed dietary rate constant from Rongelap. It was observed on Rongelap that .031% of 6975 was removed from ae “%, the diet pathway each day in addition to radioactive decay. 3 “ ’ « . ™ . « Additionally, reduc~ . « tion in dietary radioactivity on Rongelap had been observed for 13765, 705, and 0006 to be greater than that predicted by radioactive decay alone. Instantane- ous reduction fractions very similar to those at Rongelap were observed at Utirik for the 905, and 13706 nuclides. phe dose equivalent, dose equivalent rate, The lower curve on Figure 16 reflects and body~burden which would have occurred had radioactive decay alone accounted for the removal of 6900 from the Utirik environment. Since additional mechanisms could be measured for other nu-~ clides at Utirik and for the 6575 nuclide on a nearby atoll, the upper curve was chosen as the most 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; 6974 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 internajgdose 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 examinations for people on Utirik Atoll were not done. Additionally, pooled and/or in- dividual radiochemical analysis of urine was not performed during this period. . The . impact of 65. on and a5 was such ad that even 34 . if the least . . conservative dietary