bimodal activity ingestion rate distribution for 905, in the Rongelap population, Data for 6005 and 675 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 53 Fe in Figures 7 and 8 were obtained by setting Ke 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 Fe has yet to be A recalculation of >> Fe 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 70, and 1365 mean urine activity concentrations. adults were plotted. Figure 7. Mean values for adult males or all Measured values for 1376, 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 additional variations. On the basis of this observation for 17 137 Cs, a smooth body