58 FALLOUT EFFECTS—MARSHALL ISLANDERS TABLE 1. Estimated radiation doses in exposed populations Atoll No. affected* Est. whole-body gamma dose (rem) Rongelap 67 175 Ailingnae Utirik 19 164 69 14 Est. thyroid dose (rem) by age at exposure <10 yr 10-18 yr > 18 yr 800-2,000(?) 334-810 335 275-450 60-95 190 30-60 135 30 2 Includes in utero exposures (3 on Rongelap, 1 on Ailingnae, and 6 on Utirik). doses were due to gammaradiation plus radioiodines.! Because of the smaller size of the thyroid gland in children, their exposure from radioiodines was considerably greater. Although the estimated dose in a 3-year-old Rongelap child was 700 to 1,400 rads, the dose to a 1-year-old child was perhaps 2,000 or more rads. These dose estimates unfortunately had to be based on single pooled 24-hr urine sample from Rongelap people collected 15 days after exposure, with the assumption that the I-131 excreted in this sample represented 0.1% of the I-131 initially taken in (33). The short-lived radioiodines (I-132,1-133,I' 135) were not measurable but were estimated to have contributed 2-3 times the dose from I-131 to the thyroid. The possible importance of these isotopes will be referred to later. The thyroid doses to the Ailingnae and Utirik groups were arrived at by extrapolation based on relative gammadose estimates. COMPARISON POPULATIONS About 200 Rongelap people who were not on Rongelap at the time of the accident, matched as nearly as possible with the exposed group with respect to age and sex, have been examined regularly for comparison purposes. In addi- tion, during the past decade, about 400 other unexposed Rongelap people in the same age range as the exposed people and about 500 younger Marshallese have had thyroid examinations in order to establish the prevalence of thyroid abnormalities in unexposed Marshallese people. Though someofthese ‘“‘controls” have been exposed to slight residual radiation while living parttime on Rongelap and Utirik, any effects of such low levels of exposure would not be detectable and would not nullify their use for comparative purposes (13). FINDINGS DURING THE FIRST DECADE Theearly findings in the exposed Rongelap and Ailingnae groups(14) included transient nausea and vomiting, and depression of peripheral blood elements to 1 Reevaluation of early dosimetry, now under way at Brookhaven National Laboratory with additional data that have becomeavailable, indicates that thyroid doses may be higher than previously estimated (39). In this report the earlier estimates shown in Table | are used. OG | ens bow wl al