Tritium transfer from diet to human

The direct transfer of organically-bound 3H (OBT) of diet to that in the human body is reasonable, since the human body needs essential amino acids and fatty acids. Metabolic models of 3H which were recently developed for the human body took this direct incorporation into account. Data for fallout 3H in diet and human tissues were used to validate model parameters, although such data are relatively scarce. However, a simple equilibrium between dietary 3H and human body 3H was assumed for such validations. The simple equilibrium assumption means completely neglecting past 3H concentration in the human body. When the model consists of compartments which have long mean residence times, estimated 3H concentrations in the human body from the simple equilibrium assumption can differ significantly from results of adequate calculation considering contribution of past human 3H concentrations. The examples of such calculations are described in this paper. Results of the calculations show that suitable environmental 3H transfer models are necessary to use fallout 3H data for the validation of 3H metabolism models. (author). 24 refs., 9 figs