METHODS DOSI 1ETRIC EQUATIONS Declining continuous uptake of radioactive dietary items was mathematicall: modeled for each nuclide of concern. The following general equations were used t ° -(y)+ u u,/f, - 9° (¢ K:X; e (14KDE) eee K. Dt (5 Xuma (e ~C+Kp ES dt - ~CA+K:iy) OF (1) ‘ K.-Ke Ap® = p= earpeg ol . 1 zr £ qg-a° (i Xie X; LCii eeE (e - (A+Kp)t -(A+K. Jt _ i] e ~(\+K. (dX Ki)ty) » and (2) A+ ~(K- +i oi (Kirke -O+Ki) Cskg rt ¢ CAKE) 67 (Ki *) KK 1 E (KoA) (K,1 +A) E ‘ +a ° X.1 2i Oe1 ( l-e (A 4K;L )t ), (3) where t = time post onset of uptake, days, A = instantaneous fraction of atoms decaying per unit time, day”! P° = initial atom ingestion rate, atoms day~!, Kj = instantaneous fraction of atoms removed from compartment i by physiological mechanisms, day7!, Xj = compartment i deposition fraction, ¢ X; = the number of atoms in compartment i relative to the number in all compart- ments at the onset of uptake (t=0), U = instantaneous urine activity concentration, Bg oe US = subject urine excretion rate, & day~!,