Acute and chronic intakes of fallout radionuclides @ S. L. Simon er AL. . . Inorganic lodide Pool d pL A (PL—>PR) Perspiration (PR) | x . (PL—>T) (Plasma - PL) 197 Thyroid (T) + A (PBI->PL) * see Pen > PL-r) y Organic lodine Pool (PBI) Vv Urine | d (PBL» F) (U) Feces (F) Transfer rates (d*) Set PLT T+>PBI PBI-PL PBI>F PL*>U PL~*PR 1b 1.1969 0.0095 0.0760 0.0190 1.6591 0.8741 2b 1.7365 0.0095 0.0760 0.0190 1.1571 1.2681 Fig. Al. Schematic diagram of modified ICRP (1993) thyroid recycling model incorporating a pathway for iodine elimination via perspiration and transfer rates for two preferred data sets of physiological parameters (1b and 2b); see text and Table Al. study (Harrison et al. 1965) of iodine availability in cooked fish showed that boiling fish results in a nearly 60% loss of the iodine, and grilling and frying results in losses of 23% and 20%, respectively. A daily consumption of 200 g ofreef fish (probably the most commonly consumed fish since they are caught analysis of the urine samples were 12 y after exposure, the Rongelap community was then living on their homeatoll, having returned in 1957 following their post-Bravo evacuation. Living conditions and diets in 1966 can be reasonably assumednot to have been greatly different from 1954 when the most important exposure took place. in nets without the use of boats) would result in a physiologically adequate daily intake of 140 pg (200 g 700 ng g_'). Despite the criticisms of reconstructed diets, we note that diets described by National Academy Press (NAP 1994) had a range of seafoodintakes, varying from 69 ¢d‘to 480 gd"‘, with related iodine intakes of 48 to 336 yg d' (assuming concentrations typical of reef fish). The only known measurements of dietary intake of iodine among Marshallese in past decades can be derived from the urinary excretion measurements reported by Rall and Conard (1966). They made urinary iodine measurements in Marshallese from Rongelap in 1966. From 28 urine samples, they derived an average excretion of iodine in urine of 105 yg (range of 19.5 to 279). Their average value is in the adequate range, though not particularly high compared to some populations. While the collection and Urinary excretion fraction at time of sampling. An important parameter of eqn (Al) is the urinary excretion fraction, EF(t). However, there are few empir- ical data available on the excretion of '*'I as a fraction of intake at more than one week after intake. In the case of the urine sampled by Harris in 1954, the lengthy time from intake to when urine samples were collected (=16 d) adds substantial uncertainty to knowing the true excretion fraction for any individual or the true average for the group of people that contributed to the pooled sample. Hence, prediction of the urinary excretion fraction is necessary through calculations of an iodine biokinetic model. Models of the time-dependent behavior of iodine in the body have been evolving since the landmark analysis of Riggs (1952). The solution of these models requires