200 Health Physics which showed strong correlation (r = 0.87) between the sweat loss and the difference of water consumed August 2010, Volume 99, Number 2 176 wg, 0.32 for the fractional thyroid uptake, 76 wg d-' of iodine secreted by the gland, and 105 wg d| of and urine volume (Dore et al. 1975). urinary excretion of stable iodine. Set 2b (Table Al) using available computer codes.** Solving the biokinetic excretion of stable iodine. The '*'I excretion fractions The iodine biokinetic model andits transfer rates, presented in Fig. Al, were applied to derive the daily urinary excretion fractions for iodine for the six data sets model as a function of time, t, gave the urinary excretion on each day following intake. The ratio of the calculated daily excretion on each day to the acute intake, specified as input, produced the values of EF on each day following intake (Fig. A2). The estimates of EF(),Le., the '*'T excretion fractions, were found to be only moderately affected by the differences in the six sets of physiological parameters. In the three sets of parameters where the urinary excretion of stable iodine was con- strained to be 105 wg d' (sets la, 1b, Ic), the ‘I excretion fraction on day 16 varied at most by 37%. In contrast, among the three sets of parameters which constrained the fractional thyroid uptake to be 42% (sets 2a, 2b, 2c), the '*'I excretion fraction on day 16 varied by up to a factor of two. In this work, two of the six sets of physiological parameters with a daily water intake of 2 L d ' (sets assigned as |b and 2b on Table A1) were considered as preferred. Set 1b assumes a daily intake of iodine of 88 AIDE (Bertelli et al. 2008) and STELLA (ISEE Sytems, Inc.) assumes a daily intake of iodine of 121 pg, 0.42 for the fractional thyroid uptake, 76 wg d' of iodine secreted by the gland, and 51 wg d' of urinary on day 16 from those two scenarios were similar, differing by less than 35%. Hence, we used an average of the excretion fractions from sets 1b and 2b forall intake and dose estimates. The values obtained for the 'S'T excretion fraction are presented in Table Al; they are 1.76 X 10 4, 1.65 X 10 *, and 1.43 x 10 4, for days 16, 17, and 19 after intake, respectively. For Air Force and Army military personnel (weather observers) stationed on Rongerik, we also assumed a daily water intake of 2.0 L d_' with body waterlosses of 1.1 Ld! via urine as reported by Harris (1954) and 0.9 Ld! via perspiration. The parameters of the iodine model were derived assuming a daily intake of iodine of 194 weg, 0.30 for the fractional thyroid uptake, 76 wg d' of iodine secreted by the gland, 146 yg d| of urinary excretion of stable iodine, and 33 wg d' eliminated by perspiration. Using these parameter values, the '°'l ex- cretion fraction for the weather observers is found to be 1.85 X 10* for day 19 after intake.