The whole body retention at any time t-T of the fraction of initial radioactivity inputed at time Tt is rz X (ge ATK) (t-1) tou Thus, the instantaneous activity at time t-T that remains following input during dt is Af P oO e -(Kptid)t Eye CAtKi (et) dt e214 It follows that the instantaneous activity at time t-tT that remains following input during T is J T A£, Pee “(Keth)t E.x.e i*i ~(X+K;) Ct-1) dt . The solution of the integral yields a general expression that depends on the user defining t. For example, if t is the fixed uptake interval, T, plus an additional fixed post uptake interval, @, then the body burden at T + @ is given by AP°f, 2 £ yxy Ce -(A+tKp)T K -e 1 “OFR DT, a (ATK? 9g K . E As previously stated, Eq. (2) applied at Rongelap and Utirik, it was for the situation that variable time t was the uptake interval. Additionally, persons who returned to the atolls in June 1954 and June 1957 did so with an initial body burden, q®. The behavior of this contribution to body burden, q, was embodied in the q° term of Eq. (2). A similar model was used to relate