PRIVACY ACT MATERIAL REMOVED food and water(see Appendix 9C). Otherinternally Table 3 Estimated Body Burden (uCi) of Rongelap People? Activity at day | — ‘Activity at day 82 89Sr 140Ba 16 - 2.2 0.34- 2.7 0.19 0.021 131] (in thyroid gland) 103Ru Ca 6.4 -11.2 0 - 0.013 0 - 0.019 0.0 0.0 Rare earth group Fissile material 0 O 9 - 1.2 - 0.016 (ug) 0.03 0.0 cal analyses of urine samples, beginning 15 days post exposure,for ®9Sr, 14°Ba, 131], 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 foundat day 1 (extrapolated values) and at day 82. The agreement between the findingsat 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-quarterthe levels in the Rongelap group. Only isotopes of iodine, strontium, barium, and a few rare earth elements were absorbed to any significant degree. In the Rongelap group,at day 1, 99Sr and 13!I were near the maximum per- missible levels, and the estimated total amount of radioactive material in the gastrointestinal tract was about 3 mCi; whetherthis had anyrelation to the early gastrointestinal symptoms is not known.? Radiological monitoring of personne! and environment at Rongelap and otheratolls in subsequent years is discussed in Section VI. absorbed isotopes (see Table 3) were not thought to be significantly absorbed by the thyroid and probably contributed little to the dose to that gland. Conversely, the radioiodines contributed only slightly to the whole-body radiation dose. During the 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 sufficient to cause later development of thyroid ab- normalities. No acute effects were noted in anyof the people that could be related to the internal absorption of radioiodines or other radioisotopes. Contamination of the 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 of the beta radiation. Possibly slight absorption of radioiodines throughthe skin occurred. Whenthe people returned to Rongelap to live in 1957, no radioactive isotopes of iodine remained (except possibly very slight amountsof 12°), and the principal remaining isotopes (137Cs, 9°Sr), which were absorbedto low levels in the people, probably did not contribute to any significant degree to the thyroid dose.® When thyroid lesions began developing in the Rongelap children in 1963, the dose to the thvroid of the Rongelap people was reevaluated by James.?6 His estimates of the gammadose agreed approximately with the previous estimate of 175 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. Iodine isotopes are producedinrelatively high yields by the fission process. Someare too short-lived to be of consequence, but 131], 132], 133], and 155] 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 Figure 2. Beta burns (March 29, 1954).