9 Table 3 Estimated Body Burden (pCi) of Rongelap People? Activity * Activity *9Sr 149Ba Rare earth group 16 - 2.2 0.34- 2.7 0 - 1.2 0.19 0.021 0.03 MO3Ru Ca 0 0 0.0 at day 1 1311 (in thyroid gland) Fissile material 6.4 -11.2 0 - 0.013 - 0.019 - 0.016 (ug) at day 82 0.0 0.0 cal analyses of urine samples, beginning 15 days post exposure, for 8®Sr, 140Ba, 1311, 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 1 (extrapolated values) and at day 82. The agreementbetweenthe findingsat the two laboratories is close considering the techniques available at that time. Levels in the Ailingnae group were aboutone-half and in the Amer- icans about one-quarterthe levels in the Rongelap group. Only isotopes of iodine, strontium, barium, and a few rare earth elements were absorbedto anysignificant degree. In the Rongelap group,at- day 1, ®°Sr and 1311 were near the maximum per-. missible levels, and the estimated total amountof radioactive material in the gastrointestinal tract food and water (see Appendix 9C). Otherinternally 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 shghtly 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 abnormalities. No acute effects were noted in any of 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. When the people returned to Rongelap to live in 1957, no radioactive isotopes of iodine remained (except possibly very slight amounts of 1291), and the principal remaining isotopes (137Cs, 9°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 developingin the Rongelap children in 1963, the dose to the thyroid of the Rongelap people was reevaluated by James.?® His estimates of the gamma dose agreed approximately with the previous estimate of 175 was about 3 mCi; whether this had anyrelationto the early gastrointestinal symptoms is not known.” Radiological monitoring of personnel and environment at Rongelap andotheratolls in subsequent 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 thyrgj £17 in the Rongelap people, 69 rads in the Ailingnae people, and 14 rads in the Utirik group. Iodine isotopes are producedin relatively high yields by the fission process. Someare too short-lived to be of consequence,but 151I, 132], 133], and 135] 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). PRIVACY ACT MATERIAL REMOVED AQ