addition, the pathway may influence the body absorption fraction fy and Y(t) may be influenced by the presence of parent radionuclides. As mentioned above, the value of ar (D+17) is 4.0 nCi or 0.004 uCi for I-131. For iodine, the applicable biological parameters are f, = 1.0 and F,, = 86 (derived from References 14, 15, and 23). The value of Y(t) is derived from Reference 16, which contains a recent retention model. This model does not differentiate between the relatively short time from intake to organ uptake, which is satisfactory due to the rapid absorption of iodine by the body. The value of Y(D+17) used is for the first day (effectively instantaneous relative to 17 days) intake: per uCi uptake. Y(D+17) = 2.87x107* uCi/day This value reflects excreted I-131 that entered the body as I-131. However, at an early (shot-day) time of intake, the parent radionuclide Te-131m (halflife of 30 hours) exists in modest abundance--about LO percent as much as I-131, by mass (Reference [!). Although tellurium is only partially absorbed into the body, at least half of the Te-131m decays prior to elimination from the body, and the iodine produced is fully absorbed. Therefore, up to about 7 percent of the excreted [-131 on D+17 could be from intake of Te-131m. With this adjustment, Y (D+17) = 3.07x107*. Using the values of A, (D+17), fy Y(D+17), and F,, cited above, the amount of the 1-131 intake, Q? is 15 uCi. This value of Q is used to normalize the radionuclide inventory. Based on I-131 representing 0.2-0.3 percent of the total fission product activity (Reference 1!) at the estimated time of intake (discussed subsequently), the total activity intake of fission products was about 5 to 7 mCi. 4.3. PATHWAYS AND DOSE CONVERSION FACTORS. - . Researchers have arrived at various conclusions as to the dominant pathways for exposure to the Bravo contamination. The assumption of an inhalation pathway was made by Cole based on a comparison of the internal and external radiation dose estimates for the Americans on Rongerik and the natives on Rongelap (Reference 4). Cole's basic logic was that since the ratio of the internal and external doses was practically the same for both the Americans and the natives, the exposure pathways must have been similar (i.e., inhalation) and not related to the personal hygiene or 19