urine activity coficentration to body burden. Equation 3 was obtained by integrating Eq. (2). Equations (1) and (2) were used to determine the dietary removal rate constant K_ and then the initial daily activity ingestion rate required to produce the measured or derived body burden. Equation (3) was used to determine the num- ber 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 residence interval, then constant continuous uptake is achieved. Equations (1) and (2) can be converted to the constant continuous equations by replacing Ke with -X. Single uptake expressions are obtained by setting P° equal to zero. In some cases only radioactive decay may remove the nuclide from dietary items; for these cases Kp 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 negative value. tive value for Cs. Thus, K, was found to have a In the case of Rongelap and Utirik, Ke was found to have a posi- 137, Sy 65 Zn, 60 Co, and 90 Sr. This indicated that in addition to radioactive decay, some other removal mechanism decreased the radioactivity in dietary items during the residence interval. sO For the nuclide Fe, only one mea- surement in blood was published by theBNL Medical Program (Be72); thus an estimate of KE was not possible. K_ was determined by using Eq. (1) or (2) and the population subgroup mean body burdens or urine activity concentrations. A portion of these bioassay data are illustrated for adult males and females in Figures 2 to 6. Two consecu- tive urine or body-burden data points were used to eliminate the unknown ingestion rate from the equation. This method yields n-1l estimates of Ke where n was