urine activity concentration to body burden. Equation 3 was obtained by wo integrating Eq. (2). Equations (1) and (2) were used to determine the instantaneous fraction of atoms removed or added to the atom uptake per unit time, Ke» and then the ini- tial daily activity ingestion rate required to produce the measured or derived body burden. Equation (3) was used to determine the number of disintegrations that occurred in the body during the residence interval of an individual living on Rongelap or Utirik Atoll. If the mean residence time in the diet is much much longer than the resi-~ dence interval, then constant continuous uptake is achieved. Equations (1) and (2) can be converted to the constant continuous equations by replacing K, with ~h. Single uptake expressions are obtained by setting PM equal to zero. In some cases only radioactive decay may remove the nuclide from dietary items; for these cases K would equal zero. In the case of the former Bikini residents, the maturing of coconut trees during residence on Bikini Atoll caused a continuously increasing dietary uptake of 13766, tive value. Thus, Ke was found to have a negz In the case of Rongelap and Utirik, K, was found to have a positive value for 13766, 6500, 606. and 905, This indicated that in addition to radioactive decay, some other removal mechanism decreased the radioactivity in dietary items during the residence interval. For the nuclide Fe, only one me. surement was published by the BNL Medical Program (Be72); thus an estimate of K, was not possible. K, was determined by using Eq. (1) or (2) and the population subgroup mea: body burden or urine activity concentration. Portions of these bioassay data are illustrated for adult males and females in Figures 2 to 6. Two consecutive urine or body burden data points were used to eliminate the unknown ingestion