BNL20767 MARSHALL ISLANDS RADIOLOGICAL FOLLOWUP * NLA. Greenhouse and T.F. McCraw Health Physics and Safety Division, Brookhaven National Laboratory, Upton, New York 11973 and Division of Operational Safety, U.S. Energy Research and Development Administration, Washington, D.C. Abstract 20545 ' In August, 1968, President Johnson anneunced that the people of Bikini Atoll would be able co return to their homeland. Thereafter, similar approval was given for the return of the peoples of Enewetak. These two regions, which comprised the Pacific Nuclear Testing Areas from 1946 ro 1958, will probably be repopulated by the original inhabitants and their families within the next vear. As part of its continuing responsibility to insure the public health and safety in conneccion with the nuclear programs under its sponsorship, ERDA (formerly AEC) has contracted Brookhaven National Laboratory to establish radiological safety and environmental monitoring programs for the returning Bikini and Enewetak peoples. These programs are described in the following paper. They are designed to define the external radiation environment, assess radiation doses from internal emitters in the human food chain, make long range predictions of total doses and dose commitments to individuals and to each population group, and to suggest actions which will minimize doses via the more gignificant pathways. Introduction The U.S. nuclear testing programs of the 1940s and 1950s had significant Local environmental impacts on the coral atolls of Bikini and Enewetak in the Marshall Islands. The high level close-in fallout made these atolls uninhabitable for many years. Fallout from the BRAVO event, which took place at Bikini in 1954, was inadvertently deposited on the nearby atolls of Rongelap, Rongerik and UtiriR. In all, some thirteen atolls in the northern Marshalls were probably affected to a greater or lesser extent by fallout from these nuclear tests. Of these, however, the most significant long term radiological impact was on the test atolls, Bikini and Enewetak, and on Rongelap Atoll. In 1957, Rongelap was reoccupied by its original inhabitants who had been evacuated two days after BRAVO. During the past several years, definitive plans have been made to repatriate the original inhabitants of Bikini and Enewetak Atolls, and their families. It is hoped that their return can take place soon. In order to identify radiological problems from residual radioactivity in the environment, and to provide a data base for dose predictions applicable to the returning populace, ERDA (and its predecessor, the AEC), has sponsored many radiological surveys in the Marshall Islands, These surveys began during test operations and have been conducted periodically up to the present time. Results of the surveys have been published in numerous reports and scientific journals. References 1 through 12 are published reports of AEC/ERDA supported surveys of these atolls. References 13 through 29 are a portion of the published reports on work with collected environmental samples supported by AEC/ERDA. Evaluation of survey results for Bikini Atoll, the consideration of predicted exposures compared with applicable radiation standards, and the acknowledgement of the many benefits to the people if they could return, led to the decision to clean up and rehabilitare that atoll. The Department of Defense, Department of the Interior (DOI), and AEC (now ERDA) participated in a joint effort of clean up and rehabilitation of Bikini Atoll starting in February, 1969, Clean up was completed in the fall of that year, Agricultural rehabilitation and housing construction is being conducted by DOI. The decision to return the Enewetakese to their atoll led to a comprehensive survey conducted at Enewetak in 1972-1973, (19) 4 regional survey planned for 1976 will provide baseline radiological data for future dose assessments throughout nearly all of the northern Marshall Islands which may have been affected by the testing program. Environmental evaluations at Rongelap and Utirik Atolls have been undertaken $o0a2) in association with ERDA's medical evaluations program there over the past 20 years. - From all of these earlier surveys, it became apparent that periodic environmental monitoring and dose assessments must be made for Bikini, Enewetak, Rongelap and perhaps other atolls in the northern Marshalls to maintain a current radiological data base and to provide current information on individual and population doses, This followup monitoring is being performed by Brookhaven National Laboratory at the request of the Division of Operational Safety, U.S. Energy Research and Development Administration. *Research carried out at Brockhaven National Laboratory under the auspices of the U. S. Energy Research and Development Administration, By acceptance of this article, the publisher and/or recipient acknowledges the U.3. Gvernment's right to retain a nonexclusive, royaity- free license in and to any copyright covering this paper,