the highest concentration of radionuclides in the skeleton (over 90% of the body burden of the pigs), with the liver and colon containing the second highest levels of activity, and all other tissues having some measurable contamination. The iodine-131 content of human urine and the observation of bone-seeking fall-out nuclides in the human urine samples and the animal skeletal tissue samples focus the concern for internal radiation doses on the thyroid, skeleton, and bone marrow. | TABLE 3. Estimated Early Body Burdens of Radionuclides in the Rongelap Population 7 in Kbg (pCi) Radionuclide Sr-89 Ba-140 "Rare Earths” ]-131 (in thyroid) Ru-103 Ca-45 Estimated Activity, 59-81 (1.6-2.2) 13-100 (0.34-2.7) 00-44 (0-1.2) 240-410 (6.4-11.2) 0-0.48 (0-0.013) 0-0.70 (0-0.019) “Fissile Material” 0-0.016 pg s Source: Conard et al., 1980. Most radioiodine absorbed into the body is excreted within two days, therefore, urine samples, especially pooled urine samples, are an ineffective means for estimating theinitial iodine intake. From the one pooled sample collected on day 15 after the Bravo detonation, it was apparent that there was someintake of iodine-131, but, a sample at this date cannot accountdirectly for short-lived nuclides that might have contributed to thyroid dose. Although good anatomical models did not exist in 1954 for the thyroids of the children exposed, the early estimates of the thyroid doses probably were fairly accurate. Webase this conclusion on the fact that the electron dose to the glandtypically is the dominant component, and that it can be calculated with good precision given a good estimate of gland mass. The masses of the thyroids of individual Marshallese residents were not well-known, but estimates were available for children elsewhere who were of similar ages to those exposed ontheislands. The earliest estimates of thyroid doses were 1.5 Gy (150 rad) for the Rongelap population and 0.5 Gy (50 rad) for the servicemen 22