Radiological Aspects of the Bikini Atoll Environment and the Return of the Bikini People

Page 1

Radiological Aspects of the Bikini Atoll Environment and the Return of the Bikini People The role of the AEC inthe cleanup and rehabilitation of Bikini Atoll was to study radiological conditions,to provide criteria for cleanup tothe Department of Defense (DOD) and for rehabilitation to Department of the Interior (DOI), and t o perform followup radiological surveys. By way of introduction, it should be mentioned that AEC studies of radiological conditions at both Bikini and Enewetak Atolls were begun during the period of test operations and there have been periodic surveys by AEC since that time.A considerable body of information of radiation and radioactivity levels was gathered over the years. Late i n 1966, the Secretary of the Interior, responding t o an inquiry from the Bikini people, requested that AEC make an evaluation of whether these people could be safely returned to their atoll. It may be helpful to review some of the background for AEC actions at Following the request from DOI,an evaluation of existing data on radiological conditions at Bikini Atoll was made. The finding was that additional information,primarily on current external radiation levels in A n AEC field survey team spent about six weeks at Bikini during the period April-May, 1967, making measurements and collecting soil,plant, fish, and animal samples. The results of the external radiation and soils survey are published i n HASL-190 entitled, "External Radiation Levels on Bikini Atoll - May 1967", dated December 1967. A copy of that report is

Page 2

All the survey results plus reports by J. A. Tobin, District Anthropologist, Marshall Islands District, "The Bikini People, Past and Marshall Islands District, " 1 9 6 7 Bikini Radiological Resurvey - Marshalls conditions that could be expected for return of people who would take up permanent residence in the atoll using the resources of the atoll. of these reports are provided. The findings of the 1 9 6 7 surveys and comparison data from the previous 1 9 6 4 survey are used in presenting the radionuclide In 1967, the body within the Federal Government charged with providing advice to the President and guidance to Federal agencies regarding standards for the general public, was the Federal Radiation Council (FRC), which was formed in 1959. The Council consisted of the Secretary of Health, Education and Welfare (Chairman), Secretaries of Agriculture, Commerce, Defense, Labor, the Chairman of the AEC, and the Special Assistant to the President for Science and Technology. Staff work and studies were conducted by a working group consisting of senior staff menbers assigned from the various member agencies. Early in the Bikini studies and deliberations, the FRC working group was briefed by AEC staff on findings and progress. Such briefings were given periodically until the FRC was dissolved and its functions transferred to the Environmental Protection Agency (EPA). Staff of EPA have been kept

Page 3

The analytical data on the radiological conditions, and information on the people including their expected life style and diet, were evaluated by Dr. P. F. Gustafson, then of the AEC Division of Biology and Medicine. Detailed dose calculations were made for adults and children. From these deliberations, radionuclides contributing most to exposures were identified as were items of diet containing these radionuclides. The approach to development of these dose estimates for Bikini was very similar to the approach in NVO-140, October 1973, which presented the same kind of information for AEC established an Ad Hoc Committee of eight highly qualified experts to review the dose estimates and survey results. These consultants reached the unanimous conclusion that it would be radiologically safe to allow the Bikini people to return to their home atoll. The Committee also recommended certain cleanup, rehabilitation, and followup actions that have guided Federal agencies involved. On August 12, 1968, President Johnson made the announcement of the decision to allow the former residents of Bikini to return to their home atoll. recommendations and of the President's decision to return the atoll to the Bikinians is enclosed (Enclosure 5). This announcement contains a list of A copy of the announcement of the Ad Hoc Committee's the members of the Ad Hoc Committee. A s soon as the announcement was made, the High Commissioner of the Trust Territory planned a trip to Kili Island to explain what was to be done and to answer questions. The High Commissioner, who was then

Page 4

Mr.William Norwood, representatives of the DOI, DOD and AEC, and members o f the press, arrived at Kili on August 27, 1968. discuss the recent decision and there was a question and answer session with Mr. Chutaro acting as interpreter. Questions regarding this meeting have been asked periodically. were reviewed and a short report containing answers toa number of questions i s provided for your information (Enclosure 6). A meeting was held to I n May of 1970, the details of this visit Inthe approach t o cleanup and rehabilitation of Bikini,three agencies made a n agreement on responsibilities as follows: DOD would perform cleanup operations. DO1 would carryout the rehabilitation and resettlement program including agricultural rehabilitation and construction of housing and community facilities. AJX would provide guidance on radiological aspects of these programs and conduct followup radiological surveys t o confirm exposure estimates and conduct radiological monitoring of personnel as they returned to work or live at Bikini. In order to get the cleanup phase started right away, DOD and AEC provided sufficient interim funding support until additional funds that were budgeted became available. Cleanup was a joint effort conducted by DOD and AEC during the per id February t o October 1969. Radiological support for cleanup was provided by AEC with part coming through a Memorandum of Understanding between AEC and the Environmental Protection Agency (EPA). The report by Smith and

Page 5

Moore, EPA, referenced in your letter contains results of this effort along with the additional radiation measurements made during cleanup. independent estimate of exposure due to external radiation was made by Smith and Moore for a child born on Bikini Atoll in 1970. The 5,30, and 7 0 year values may be compared with Gustafson ' s estimates for the same times for "External" exposure. Part of the difference between the two sets of values, for instance 3.33 rad s in 30 years by Gustafson versus 5.3 rad s for Smith and Moore (5,275 mrads i s 5.3 rads), comes from a correction made for external radiation contribution from cosmic ray exposures in the reported data used by Gustafson. Note that the reported radiation levels in the Smith and Moore report include natural sources. See footnote on page three of that report. The cosmic ray measurements at Bikini made by the AEC Health and Safety Laboratory (HASL) indicated a dose rate of about 3.4 p,R/hr (microroentgens per hour). The 30 year exposure from this source would be 3.4 G / hrx 24 h r / dayx 365 day ly r x30. comparison of the two values,including natural background for each, would be about 4.2 versus 5.3 rads. It should be noted that these estimates do not include any credit for reduction of exposure that may come from use of coral gravel in the village area or from the shielding provided by housing. Conversely, the Smith and Moore estimates do not include any contribution from internal radioactivity.Since internal radioactivity comes through the food chain the contribution to the total dose from that source will change with time as locally produced foods become available. We plan to continue to make periodic surveys and t o update dose estimates as new information is obtained. Such estimates will, of course,include internal

Page 6

During cleanup,the agricultural rehabilitation program got underway with removal of vegetation and replanting of coconut trees. that time,construction of houses was started. Comments were provided by AEC staff on use of local sources of sand and coral aggregate for housing construction and on design factors that were considered important i n minimizing indoor radiation exposure levels.Lest there be misunderstanding as to the AEC interest in this phase of rehabilitation,it should b e pointed out that construction of houses that are good radiation shields was not a prerequisite for return of the atoll. AEC concern is that if there are options in selecting construction materials,for instance,the source of local materials such a s sand and coral aggregate,or in the design of the houses, those options giving lower radiation levels in the houses are preferred. This is in accord with the fundamental radiation protection principle of keeping exposures a s low as practicable. Followup radiological surveys were sponsored by AEC at Bikini in 1970, 1972, and 1974. Radiological monitoring of persons resident at Bikini are and will continue to be conducted by Dr. Robert A. Conard of the AEC ' s Brookhaven National Laboratory as recommended by the Ad Hoc Committee through 1972 are presented in WASH-1273, "Exposure Rate Reduction on Bikini "Levels of Environmental Radioactivity on Bikini Atoll " ,printed in 1974 Soils, and Ground Water at Bikini Atoll, 1967-1970", February 1971 (Enclosure Results of measurements and of analysis of samples collected LO), and inthe Smith and Moore report SWRHL-lllr, "Report of the Radiological

Page 7

Cleanup of Bikini Atoll " , January 1972 (Enclosure 11). Principal investigators are reviewing a draft report of the 1972 survey. That report will be published For several years, personnel radiation monitoring has been carried out on workmen and Bikini People on Bikini by a team from Brookhaven National Laboratory headed by Dr. Conard. During his 1974 visit,Dr. Conard monitored the people on Bikini Island and took samples of the environment. A report of the 1974 results will also be prepared. Preliminary information on the 1974 Bikini survey from Dr. Conard indicates the body burdens of cesium-137 for 18 males and 13 females are very low, about 3-4% of the applicable standard. The addition of coral gravel in the yards of houses appears t o reduce radiation levels inthe yards by about 50%. It i s our current plan to continue such surveys. Our detailed survey plans will, of course, depend upon the actions and desires of the returning people. It is likely that annual field trips will be made initially with less frequent surveys later depending on results obtained. Preliminary data from the latest survey are essentially in agreement with earlier survey findings. der f ved from the 1967 and earlier surveys are still valid.Available radiological information is reviewed as each field trip is planned. One change in the atoll has been construction of houses on Bikini One of the objectives of the 1972 survey effort at Bikini was t oI sland. determine the reduction in radiation exposure that can be expected because of the time people spend indoors. Table 1 of WASH-1273 presents results of measurements made outside and inside the Bikini houses in various stages of

Page 8

completion at that time. i s 44-4877, and for one occupied house i s 51%. Note i n Table 2that the average exposure levels outside the houses are less than 44 pR/hr and more than half of the measurements were less than 20 pR/hr. While there had been some scraping of soil where houses were constructed,the layer of coral gravel recommended by the Ad Hoc Committee was not yet in place. Lower levels are expected when this is done, and preliminary results from the 1974 survey indicate this is indeed the case. Asfor dose rates inside the completed houses ("Slab, Walls, and Roof"), the average level in Table 2for 10 houses in the center of the building,at a height of 3feet is 11.2 pR/hr o r 96 mR/yr. About one third of this is from natural background. Values reported for 17 houses inthe New York area range from 29 t o 90 mR/yr. " Investigations of Natural Environmental Radiation", Science 131, pages 903906, 1960 (Enclosure 12). It should b e pointed out that the source of New York exposures i s almost entirely natural radioactivity in the building materials and environs where the levels change little with time.At Bikini, the source is primarily cesium-137 from testing that was deposited in the surrounding soil with very little radioactivity in the materials of const ruc - tion.Since cesium-137 decays with a halftime of 30 years,the external radioactivity levels at Bikini from this source will continually decrease, AS for the guideline for evaluation of exposures at Bikini Atoll,the Table 2 shows that the reduction factor for "Slab basic numerical guide for whole body and bone marrow i s 500 mrem/yr (milli rem per year). The 500 mrem/yr standard is applicable where individual exposures

Page 9

can be determined. When the range of exposures is not known, the guide is 170 mrem/yr with exposure determined as an average for the population t h e r e is no threshhold below which one can be certain there is no radiation planned to assure that exposures will be known for both individual adults Both of these standards were developed using the assumption that The followup surveillance of the Bikini environment and people is For completeness, there are several additional items that should be a. A question regarding planting coconilt in the Peter-Oboe complex. b. Questions regarding any restrictions on digging foundations for houses and whether work crews could drink well water on Bikini C. Followup items from the Ad Hoc Committee recommendations relative to a dietary supplement of powdered milk and removal of soil for Answers to questions in (a) and (b) above were provided in a letter to High Commissioner Edward Johnson dated June 17, 1971. This guidance specifies that coconut may be planted in the Peter-Oboe complex except for the island of Tare (Eneman). There are no restrictions on digging foundations on Bikini Island and no radiological restrictions on use of well water oil Bikini Island. A copy of the letter is provided (Enclosure 13). The question of the best way to provide a calcium supplement to the diet for people living in Bikini Atoll t h a t will be acceptable to both

Page 10

adults and children is under consideration. We are considering the possibility of using one or more of several food items, including powdered milk, so as to give a choice to the peopie. We expect to make suggestions on this followup item before the locally produced pandanus becomes a significant part of the diet. Our followup surveys will check on pandanus plantings to insure that the recommendation of the Ad Hoc Committee regarding soil removal at pandanus planting sites has been implemented. The measurements made and samples analyzed through our periodic surveys will be used as a basis for recommendations as to the time of rehabilitation of islands outside the Bikini-Eneu complex and agricultural redevelopment of islands outside the Bikini Eneu and Peter-Oboe complexes. In response to the question you raised about the health risks to people who will return to live on Bikini, the data f o r such risk assessments are available in the recent reports of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and of the U. S. National Academy …