tion levels along the center of the sand island were observed to be about 0.015 mR/hr. Samples of sand from the island and bottom sediments from Bravo Crater were collected. The sand contained 60co, 137¢s, and !25sbh, 69¢o was responsi- ble for about 60 percent and 137¢3 responsible for about 30 percent of the ex- posure rate on the sand island. Aomen-Iroi active scrap, reduction of land crab population, a dietary supplement of calcium. The Committee also recommended periodic resurveys of the atoll. There were other recommendations for agricultural and village construction activities expected to reduce the radionuclide content of pandanus and reduce external radiation levels in village and dwelling sites. The bottom sediments contained 207ni in addi- tion to the above but 60¢o was the predominant radionuclide. : lex The northern rim of the atoll contains a long string of four narrow causeway-connected islands. From east to west these are Aomen, Lomilik, Odrik, On August 12, 1968, the decision was announced that the Bikinians were to be returned to their atoil.(3) and Iroij. Vegetation is sparse along this string of islands. Since two tests had been conducted near the center of this complex (see Figure 1), the radiation levels along the string of islands were quite variable and there were considerable quantities of radioactive scrap metal. The survey route passed down the center of the islands and causeways. to their home islands. To begin che planning, High Commissioner W. R. Norwood of the Trust Territory of the Pacific Islande led a part of Trust Territory Measurements ranged from 0.005 officials, nine Bikini natives, USAEC and DOD representatives, and members of the press, back to Bikini in late August 1968. to 0.020 af/hr on Aomen, 0.020 to 0.330 mR/hr on Lomilik, 0.010 to 0.040 mR/hr on Lroij, and 0.003 to 0.007 mR/hr on the causeways. The higher levels on Lomilik were in depressed areas with clay-like soil. Cleanup and Followup, 1969-1970 A soil sample taken from the area of highest radiation level indicated 60co contributed more than 75 percent of the total exposure rate. The first units of the atoli cleanup force arrived at Bikini Atoll in Traces of February 1969, The DOD directed the cleanup phase of the rehabilitation project which Lasted about eight months. The Department of the Interior is 106gh, 10lRh, 144ce, [55gu, and 24lam (and thus 239pu) were also detected. managing the agricultural restoration and housing construction phases of the project. The AEC provided radiological safety and monitoring support for cleanup operations and is conducting followup surveys. Sample Analysis and Data Evaiuation The analysis of collected environmental samples such as marine life, coconut, arrowroot, pandanus, birds, land crabs, and soil and the calibration and development of correction factors for instruments continued in 1967. The next significant step was taken by Dr. Philip F. Gustafson of the Division of Biomedical and Environmental Research, USAEC, * who collected and summarized the deta from all past surveys. Additional information was obtained on radiological conditions during cleanup. Clearing of scrub vegetation provided easy access to island areas. Additional soil and food samples were collected and analyzed and many radiation measurements made with portable instruments. Results of analysis of soil taken from the location having the highest external gamma level in the atoll (from Eneman, an island where houses are not to be built and where replanting of co- Included in this material were reports from the Trust Territory District Agriculturist and from the Trust Territory District Anthropologist. Dr. Gustafson prepared estimates of potential exposures, both internal and external, for a returning population having living habits and diet that are expected to apply to the Bikinians. Also prepared were tentative recommendations with regard to the basic question of whether from a radiation exposure viewpoint the Bikinians should be allowed to return.** ad Committee of eight expert consultants to consider the question of return of the Bikinians. The Committee members reviewed the survey data, Dr. Gustaf- son's reports, and consulted with the team members of the 1967 survey. Follow- ing this review, the Committee stated that on the basis of information provided, the exposures to radiation resulting from the repatriation of Bikini people would not offer a significant threat to their health and safaty.(3) key recommendations for actions to further reduce exposures were restriction of rehabilitation for the present to the Bikini-Eneu Complex, removal of radio- conut trees is restricted), showed a level of 239pu in dry soil of 410 pCi/g. (4) Analysis of food items collected during cleanup indicated mean concentrations of 137¢— and 90sr chat were essentially in agreement with those obtained in 1967. For 1969 and 1970 collections, there were no striking differences between average values for edible foods of marine origin, including the sea birds, compared with values reported in 1967.45) Internal dose estimates performed for wee EERrE In April 1968, the Division of Biology and Medicine, USAEC, appointed an The USAEC and United States Department of Defense (DOD) were requested to work with the Department of the Interior in planning and carrying out a comprehensive program for returning the Bikinians the 1967 sample collections appeared-to be valid for the 1969 data as well. Externel gamma surveys during cleanup confirmed the earlier measurements, Estimates of total exposdre for children for the 1967 and 1969 dats are as follows: Total whole body gamma exposure (Rads) Time 5 30 70 (years , *Now at Argonne National Laboratory, Argonne, Illinois, USA **Copies of the technical data are available for examination at the Public Documant Room in USAEC’s Washington, 9.C. Office at L7L7 H. St. 1967 1969 1,16 5.32 9.74 0.75 5.28 9.36 1970 Survey Sampling for 239pu in air at Bikini and Eneu Islands was conducted during May-June 1970. For Bikini the results ranged from 0.6 X 10-4 to 5.4 X 104 pCi/m3. Results for Eneu were 0.4 K 10-4 pci/m3, These concentrations are comparable to those found in the U.S. and are lower than the Federal Radiation Council, FRC, guides for soluble plutonium in air (6 X 10-2 pCi/m? for individ- uals and 2 X 10-2 pCi/m3 for population groups) by about two orders of magnitude, .