body burden means for adults:on Ucirik and the observed Ke rate constant froin Rongelap. It was observed on Rongelap that .031% of 65 ““Zn was removed from tlie diet pathway each day in addition to radioactive decay. Additionally, reduci ion ; . , 137 s, 90 Cc Sr, and 1 Co in dietary radioactivity on Rongelap had been observed for to be greater than that predicted by radioactive decay alone. Instantaneous re- duction fractions very. similgr ko; those; qt" Rongelap were j observed at Utirik for the 705, and 137¢, nuclides. The lower curve on Figure 16: reflects the dose equivalent, dose equivalent rate, and body burden which would have occurred tid radioactive decay alone adeounted: for the removal of $525 from the Utirik envi - ronment. Since additional!sechanisns couldbe measured for other nuclides at Uririk and for the 52m nuclide on 8 nearby #to}l,* 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 dese equivalent iate i for each nuclide. tq An obvious difference relative to the Rongelap history exists; O20 not 1370, 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 o! each nuclide contributing to the internal dose equivalent. In fact 600, and 6378 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 exiuiinations for people on Utirik Atoll were not done. Additionally, pooled and/uv in- dividual radiochemical analysis of urine was not performed during this peri. . 60 The impact of 6525 and Co was such that even if the least conservative rate 34