9 food and water (see Appendix 9C), Otherinternally Table 3 absorbed isotopes (see Table3) were not thought Estimated Body Burden (uCi) of Rongelap People? Activity at day | 89Sr 1.6 - 2.2 Ba 0.34— 2.7 Fissile material Q Rare earth group 181] (in thyroid gland) SRuCa 0 6.4 0 0 -1.2 -11,2 - 0.013 - 0.019 =+0.016(ug) Activity at day 82 0.19 0.021 0.03 0.0 0.0 0.0 cal analyses of urine samples, beginning 15 days post exposure, for ®®Sr, !4°Ba, 1521, the rare earth group, and fissile material. As expected, the Rongelap people had the highest body burdens. By 6 months, beta activity in the urine samples was barely detectable. Table 3 shows the main isotopes found at day | (extrapolated vaiues) and at day 82. The agreement between the findings at the two laboratories is close considering the techniques available at that time. Levels in the Ailingnae group were about one-half and in the Americans about one-quarter the levels in the Rongelap group. Only isotopes of iodine, strontium, bariym,- and a few rare earth elements were absorbed to any significant degree. In the Rongelap group,at day 1, 8°Sr and 1511 were near the maximum perrissible levels, and the estimated total amountof radioactive material in the gastrointestinal tract was about 3 mCi; whether this had any relation to the early gastrointestinal symptoms is not known.? Radiological monitoring of personne} and environment at Rongelap andotheratolls in subsequent to be significantly absorbed by the thyroid and probablycontributed little to the dose to thar gland. Conversely, the radioiodines contributed only slightly to the whole-body radiation dose. Duringthe early period after the fallout, radioiodine was recognized as possibly its most hazardous constituent, but the estimated dose to the gland of 100 to 150 rads was not considered suffi- cient to cause later developmentof thyroid abnormalities. No acute effects were noted in any of the people that could be related to the internal absorption of radioiodines or other radioisotopes. Contaminationofthe skin resulting in extensive beta burns in the neck region in 70% of the people (see Figure 2) probably did not contribute to the thyroid dose because of the low energy ofthe beta radiation. Possibly slight absorption of radioiodines through the skin occurred. ; Whenthe people returned to Rongelaptolive in 1957, no radioactive isotopes of iodine remained (except possibly very slight amounts of 1291), and the principal remaining isotopes (}57Cs, %Sr), which were absorbed to low levels in the people, probably did not contribute to any significant degree to the thyroid dose.® Whenthyroid lesions began developing in the Rongelapchildren in 1963, the dose to thethyroid of the Rongelap people was reevaluated by James.26 His estimates of the gamma dose agreed approximately with the previous estimate of 175 + WS 2 ; : F - LEcanemig aw a wat arn yh - wae ” hs years is discussed in Section VI. 5. Thyroid Dosimetry The fallout produced several possible sources of radiation exposure to the thyroid gland. The gamma radiation resulted in thyroid doses of 175 rads in the Rongelap people, 69 rads in the Ailingnae people, and 14 rads in the Utirik group. lodine isotopes are produced in relatively high yields by the fission process. Someare too short-lived to be of consequence, but 131I, 132], 133], and 1351 are sufficiently long-lived to cause a considerable dose to the thyroid following internal absorption and concentration in that gland, and these were absorbed both via inhalation and via ingestion in SOObIOb Figure 2. Beta burns (March 29, 1954). PRIVACY ACT MATERIAL REMOVED