TRITIUM TRANSFER FROM DIET TO HUMAN

The direct transfer of organically-bound H-3 (OBT) of diet to that in the human body is reasonable, since the human body needs essential ami no acids and fatty acids. Metabolic models of H-3 which were recently developed for the human body took this direct incorporation into accou nt. Data for fallout H-3 in did and human tissues were used to validat e model parameters, although such data are relatively scarce. However, a simple equilibrium between dietary H-3 and human body H-3 was assum ed for such validations. The simple equilibrium assumption means compl etely neglecting past H-3 concentration in the human body. When the mo del consists of compartments which have long mean residence times, est imated H-3 concentrations in the human body from the simple equilibriu m assumption can differ significantly from results of adequate calcula tion considering contribution of past human H-3 concentrations. The ex amples of such calculations are described in this paper. Results of th e calculations show that suitable environmental(3)H transfer models ar e necessary to use fallout H-3 data for the validation of H-3 metaboli sm models.