The whole body retention at any time t-T of the fraction of initial radioactivity inputed at time T is ~ boy eA tKi) (t-1) wl Thus, the instantaneous activity at time t-T that remains following input during dt is he peeREMAN zX,e “OtKU) CET) It follows that the instantaneous activity at time t-T that remains following input during T is J T ° AFPee ~(Kg+A)T -(A+Kj) (t-T) L.x.e° L"i 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°£) Lixy Ce -(A+K_)T ~Q4KQ)T -C0+Ky) BO ae mye i)? . ri As previously stated, Eq. (2) applfed 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