calculations, it is assumed that the diet remains constant, and that the loss of radioactivity in the diet is by radiological decay only. The 30-year cumulative doses of Table D.7 apply to the period 1987-2016. In the next 30-year period the doses from cesium-137 and strontium-90 would be no more than half of these. The transuranic dose continues to increase with time but the dose due to the transuranics would be less than 3% of the total dose over 50 y. Of the principal contaminating radionuclides, cesium-137 is, therefore, the most important (Table 0.8). It ac€counts for 93 per cent of the 30-y integral bone marrow dose and practically 100 per cent of the dose to most other tissues. Strontium-90 contributes 7 per cent of the 30-y integral bone marrow dose while the contributions of the plutonium and americium are less than 1%. Of the foods, coconut products supply some 83% of the cesium intake (Tables 0.3, 0.4) and Pandanus fruit and local meat (but not fish) supply about 12%. Coconut, therefore, is responsible for about 83% of the whole-body dose. The preponderance of cesium-137 in determining the dose is the result of a much larger intake of 7Cs than of other radionuclides, amplified by much greater absorption from the gut, so that the cesium-137 entering the circulation is about 300 times that of strontium-90, and more than one million times that of the transuranics combined. 4. Leeway An additional margin of safety (in addition to the factor of 1.75 already applied) is implicit in these calculations, which optimistically take 1987 as the year of resettlement and assume. that coconut and other crops will be immediately available. A more realistic timetable, allowing for plans,to be drawn and approved by all concerned, contracts let, a work force assembled, and the Congressional appropriation of funds, would forsee 1987-88 as a very early date for starting the work, and 1990 as an early date for resettlement of Bikini Island. To this must be added 8 years for the coconut plantations to become significantly productive, j.e., in 1998. This 10-year delay will ensure an additional loss of 20% in cesium-137 and strontium-90 by spontaneous decay. There may also be a continual, albeit small, loss of radionuclides into the groundwater and thence into the lagoon. In addition, the doses reported here are calculated using the average value for all of the parameters in the dose model. We have shown that the data for almost all of the parameters are log-normally distributed and, therefore, so is the final distribution of estimated doses(5). The doses calculated using the average value for the model parameters then fall between the 65-70th percentile so that about 70% of a returning population would be expected to have a dose less than or equal to the listed doses. The doses calcualated using the median value for all model parameters would fall at the midpoint of the distribution, that is 50% would be expected to have doses less than and 50% doses more than those listed. These "median" doses way td be about 40% less than the doses listed here and in the LLNL report . 5. Dose and Soil Specific Activity The internal dose is calculated from the amount of radionuclide ingested in food; it is thus directly proportional to radionuclide intake. How, then, does the magnitude of dose change when the specific activity of the soil changes; for example, when decontamination is carried out or when one goes from island to island? 3000169 D-4