Combining terms ne | E(t) = £, u u(o) Ss 1A.k, u 1621 isl ec + ¢) ~Ce, +r) “* (T + Oy) A+ k, + 4 1 To estimate E, we measure the activity concentration and miltiply it by the age-dependent urine excretion rate. We calculate the activity uptake rate and integrate over the exposure interval.