The whole body retention at any time t-t of the fraction of initial radioactivity inputed at time T is Eye Ati) Cet) neu Thus, the instantaneous activity at time t-T that remains following input during dt is AE, Pee” (KEFAIT Boxe A*Ki) (t-T) 4. ° It follows that the instantaneous activity at time t-t that remains following input during T is T “(Ket )T ~(A 4K 3) (t-T) J ° AF, 1 P%e r.x.e dt. i“i 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 + 9 is given by AP°£ Lixg Ce -(A+KE)T —(AtK;)T (A #K) 6 Be ne mye * RK, 7K 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