respiraOn the basis of Figure 4, the equations for the compartments of the tory tract and lymph nodes plus the transfer to the gastrointestinal tract and blood are Tort 7 *pYnpp * 2a%raa + *e%pe * g%eg + Bn (42) Th 7 npa * e%rBe * *e%tBe * Ym * f3%GIT (43) A¥ypa/dt = FPsh- Og + D9ypa (44) dygpy/dt = A094- On +) ¥npp (45) Yyp = Yura + Ynpp (46) dy ppofdt = fame QO, + DY ope (47) dyppg/dt = fPgdnm Og t+ a ¥rpa (48) Yontg ~ Otvre + *p¥Pg) TrBke (49) You = Ytpc * Yrpa * Yraeg (so) On + pe 61) £,DoAm- QO, + e)¥ pe (52) dyp,/dt = f,0.A,- Gy + oY pp (53) dyp,/dt = EDA Og tA)pn (54) Yp = Ype * Ype + Ypg * YPh (59) dypag /t = Fn%pH 7 Og * Dimi (6) dv yp/dt = Cm ED ALY pH 7 d EME (57) dyp,/dt * dyp_/dt = EDS AR Yum 7 Yomi + Yume 666 (58) where r, A T, ys Hy, f, and A,are defined previously in the ICRP II model and the subscripts, where different, refer to the compartments and the pathways listed in Figure 4 and Table 9. TrpFe is the residence time of material following pathways f and g in the tracheobronchial region (days), D,.D,.D,. are the fractions of inhaled material that are deposited in the nasopharyngeal, tracheobronichial, and pulmonary regions, respectively, of the respiratory tract (see Figure 4 and Table 9). Values of most of the parameters in the above equations are given in Table 9 (USNRC, 1976). T, is assumed to one hour or 1/24-day (Snyder, 1967; Kotrappa, 1968, 15B58 , while f£, is identical to £ (0,003 percent) in the ICRP II model. The equat fons tor GIT, liver, kidney, bone, and total body are identical to the ICRP 11 model with identical parameter values except for the following values which apply to all transuranic elements: f = 0.45, £ = BL BBN 0.45, ™ 40 years, and tT, 7 100 years. Stuart, Dionne, and Bair (SDB) Model Stuart et al, (1968) developed models to describe the distribution and retention of plutonium in the body following a single inhalation. These models were based on the results of several studies with dogs and these results were extrapolated to where they might apply to man. The short-term model is shown in Figure 5, while the long-term form is shown in Figure 6. Stuart et al. (1971) revised the long-term model and these revisions are incorporated into Figure 6. Stuart et al. (1971) combine the nasopharyngeal and tracheobronchial regions of the Task Group model into one compartment but expand the pulmonary region into two compartments: one with a constant biological half-time of 3 years and another with a variable half-time. They also add compartments for abdominal lymph nodes and treat the transfers from the pulmonary region to lymph nodes in a slightly different manner than the Task Group model. In addition, they include feedback pathways for liver to the gastrointestinal tract (GIT) and for liver, kidneys, and skeleton to blood. Since they only applied this model to inhalation, they did not consider the transfer from GIT to blood since the fraction transferred is so small (less than 0.01 percent). On the basis of Figures 5 and 6, the equations for the compartments of the respiratory tract and lymph nodes plus the transfer to GIT and blood are