island in 1957, they accumulated low levels of radionuclides (principally 657, 137¢s5, Ose, and 2°Fe) from marine and plant foods -- primarily pandanus, coconuts, breadfruit, coconut crabs, and fish. (The crabs are a food delicacy, which, because of unexpectedly high levels of absorbed radiocesium and strontium, had to be banned from the diet until recently when the levels became acceptable.) The people were also exposed to low levels of residual gamma radiation over and above the natural background radiation. Fig- ures 1 and 2 of A pendix II show the changes in estimated body burdens of 137¢5, 657n, and 5 Sr in the Rongelap people. 90sr reached its highest levels of about 12 nCi in adults and 22 nCi in children between 1962 and 1965 and thereafter showed a downward trend. 137¢s body burdens in adults reached a peak in about 1965 of rough ly 0.7 wCi (23% of the permissible level for general populations). The 552n level reached a peak of 0.5 uCi during the first year or so after the return, generally below the 137¢, level, and became nondetectable thereafter. From the data in Table 4, Appendix II, the total-body dose for inhabitants living full-time on Rongelap from 1957 to 1979 was estimated to be nearly 4 rads. It should be noted that the actual dose was probably lower because the people spent about half their time away visiting other atolls. Since 1957, the people who had returned to live on Utirik Island have been included in the personnel monitoring program. The estimates of initial exposure for the Utirik people, particularly for the thyroid gland, were subject to greater uncertainties than those for the Rongelap people. Not the least of these uncertainties was the degree of exposure to short-lived iso- topes of iodine in the Utirik population. Available data, however, indicate that exposure of the Utirik people was considerably below that of the Rongelap people, perhaps 1/10 as much. (Radioanalyses of animal, plant, and other samples from Utirik shortly after the accident showed levels about 1/10 of those for samples from Rongelap.) Following their return, the levels of accumulated long-lived radionuclides in the Utirik people, measured at the same time as in the Rongelap people, were only about 1/3 as high. However, since these people returned to live on Utirik in July 1954 (three years before the return of the Rongelap people in 1957), during the first few years they were exposed to somewhat higher levels of radionuclides, particularly 652n, than were the Rongelap people on their return. This accounts for the higher body burdens estimated in Appendix II for the Utirik inhabitants during the first few years after their return. full-time The total-body dose for inhabitants living on Utirik from 1954 to 1979 was estimated the early contribution of 652n. Again, to be about 17 rads, due mostly to the actual exposure was probably lower because the people were away about half the time visiting other atolls. Reexamination of dosimetry analyses for the Rongelap and Utirik people, for both initial and residual exposures, is being carried out at this Labora- tory. Personnel and environmental monitoring are being continued on a regular basis. 2. Bikini In 1946, before Operation Crossroads, the residents of Bikini were evacuated. After stays at Rongelap and Kwajalein which proved unsatisfactory, they were relocated on Kili Island in the southern Marshalls, - 83 - which also