OFFICIAL USE ONLY of the soil as occurred during the stripping operations on Bikini produced an additional reduction in exposure rates. Soil samples from the other islands showed varying amounts of ©9Co and 102mgh in addition to the 137¢s. The reduction in exposure rate due to radioactive decay on these islands should be much more rapid than for Bikini because of the shorter half lives of 60¢o and 102mgn, By comparison of the decay curves for these islands with that for Bikini, it can be seen that within approximately 10 to 15 years only Eneman will have an extérnal background higher than that of Bikini. It is recommended that a resurvey to verify this projection be conducted in about 10 years in anticipation of unrestricted use of these islands which have higher radiation levels than Bikini. In the meantime, the recommendation of the Ad Hoc Committee restricting rehabitation to the Bikini-Eneu complex should be followed. The remaining islands of the atoll are lower in radiation levels than Bikini and it would appear that a restriction on continuous occupancy would not be needed. This is particularly true of the Aerokoj, Aerokojiol, Bikdrin complex where the lowest concentrations of radionuclides and lowest levels of radiation are found. Coconuts from Aerokoj were lower in 137¢s and 90sr content than coconuts from Bikini or Eneu. ment of these islands should be considered. Agricultural develop- While the external levels on Lele are as low as those on the other three islands, the fact that it is contiguous with Eneman would make it advisable to restrict the use of this island at the present time. The causeway joining Lele to Bikdrin makes a logical dividing line for indicating this restriction. Analyses of food items growing on the atoll indicated mean concentrations of 137¢s and 90Sr which are essentially in agreement with those obtained in 1967. When new species of food plants are introduced to the atoll, additional analyses: of mature specimens will be needed, Internal dose estimates have been performed by Gustafson utilizing the 1967 data and would appear to be valid for the 1969-1970 survey data as well. The concentrations of ?9Sr in the food chain would seem to be of greatest concern with respect to internal dose. Removal of top soil from the site of newly planted pandanus and possibly breadfruit trees, and the addition of a calcium supplement to the diet, as recommended by the Ad Hoc Committee, should be most effective in reducing the dose due to 90sr, The results from Eneu air samples are comparable with 1968 air concentrations for 239Pu in the United States. Bikini air sample results range from slightly higher than Eneu to approximately an order of magnitude higher (for the station exposed to the dust from the jeep traffic on the lagoon road). 20 OFFICIAL USE ONLY