where R(t) = fraction of initial atoms administered which remain in the body at time t not corrected for radioactive decay. The fractions of 6006 atoms in each compartment at the end of each individual's residence iaterval were calculated assuming a constant continuous uptake regime for 8000, Individuals were assumed not to have an initial body burden at the onset of residence om Bikini Island. The parameters for biolog- ical removal rate constants and fractions of activity distributed to each of the four compartments are od- tained from equation 3. For the eight individuals, eighty-four to eighty-eighte percent of the total body 6065 atoms would be in the long term compartment, nine to twelve percent in the intermediate compartment and three percent in the two remaining short term compartments. In January, approximately 140 days after departure from 3ikini, two percent of the atoms would have been in the intermediate compartments and 98 ver cent in the long term compartment. In May, the relative contribution of atoms from each compartment to the total atom content in the body would have been .7 percence and 99.3 percent respectively. body burden between January, This corresponds to a change in the 8009 1979 and May, 1979 of 14 percent. The observed decline in the body burden was 44 percent. The intermediate and long term biological removal rate constants deter- mined by Smith and Letourneau (Sm72, Le72) do not describe the retention of 6004 for the Marshallese population. From the Marshall Islands data, one cannot estimate the number of compartments that should be used in the 606, retention model, but an estimate of the long term biological removal rate constant was calculated using equation l.

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