bimodal activity ingestion rate distribution for 90, in the Rongelap population. Data for 606, and O570 were not sufficient for analysis for the Utirik Atoll residents. Values for Ke observed at Rongelap were assigned to Utirik males and females and body burden histories for population subgroups were reconstructed using Eq. 1 or 2. Figures 7 and 8 illustrate the derived mean adult body burdens for all significant nuclides studied on Rongelap and Utirik. This method provides a best fit of the data shown in Figures 2 through 6, and provides a body burden history during the early years post return at Utirik, a time when body burden measurements were not made. Actual data points are also plotted to demonstrate the fit. The curves shown for >> Fe in Figures 7 and 8 were obtained by setting K, equal to zero. future ones. This underestimated the initial body burdens and overestimated Since >> Fe contributed less than 1.0% to the total dose equiva- lent, an arbitrary assignment of Ke based on observed values for the other nuclides was not attempted. During 1974, another series of blood samples was obtained from Rongelap and Utirik (Co75). reported. Analysis for 9556 has yet to be A recalculation of 9 K¢ body burden and its impact on early dose equivalent rates will be conducted when the data is made available. A substan- tial change in dose equivalent is not to be expected. Figure 4 and Figure 6 illustrate the observed adult histories of 90. and 1376, mean urine activity concentrations. adults were plotted. Figure 7. Mean values for adult males or all Measured values for 13764 body burdens were also shown in A much smoother curve was plotted in Figure 7 and it was determined that the collection and analysis technique for urine samples introduced the addi. oo, tional variations. . . . 7 On the basis of this observation for 13 Cs, a smooth body 17