Summary of Personnel Monitoring (Bioassay) of People Living at Bikini Atoll 1969 - 1975

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SUMMARY OF PERSONNEL MoNITORING (BIOASSAY) Ol? PEOPLE LIVING AT BIKINI [~: The bioassay data in the handout at the September (1975) Department of Interior meeting on the Bikini people has been updated in this report to include the recently completed 1975 urine data. It should be noted that in the surmnary table of urine analyses (Table 4 of the original handout) plutonium data have been omitted since Mr. Edward Hardy at the ERDA Health and Safety Laboratory (who did the analyses) advises that because of the large error in counting plutonium at near background levels, the results should not have been averaged. However, the individual urine plutonium data are now reported In 1969 a group of about 30 Marshallese people settled in a work camp on Enue Island at Bikini Atoll to carry out the rehabilitation program. Many of the group commuted to Bikini Island about 7 miles away where they worked during the day. By early 1972 three Bikini families (about 50 people) plus 20-30 workmen moved to Bikini Island and lived on the southern end of the Island in frame buildings remaining from the earlier weapon testing program. The three Bikini families later moved into several of the completed concrete houses in the southern sector near the lagoon. The size of the population living on Bikini has not changed much as of 1975. Radiological monitoring of personnel on Bikini Atoll has been done annually by the Brookhaven National Laboratory (BNL) medical team as specified by the 1968 Ad HOC Committee recommendation. The monitoring procedures are not medical examinations and were performed by experts

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from BNL accompanying the team. Medical examinations have not been done, since they were not indicated in view of the low levels of radiation to which the people are exposed. However, when physicians from the BNL medical team are at Bikini they have, for humanitarian reasons, examined and treated many individuals at the request of the individuals or health aide. NO health problem or sickness has been noted which could be related to radiation exposure. The results of bioassay procedures have been most important in forming a basis for reassurance of the people living at Bikini regarding their radiological safety. In order to assess the radiological hazard the following bioassay procedures have been carried out: 1. Radiochemical analyses on urine samples: (individual 24 hour and pooled samples). These analyses require sophisticated chemical procedures and are perfo~ed by the ERDA Health and Safety Laboratory in New York City. Such radiochemical analyses have also been carried out on water and indigenous food products. Analyses were made for , Cs and F%. On one occasion nasal swabs taken on Bikini worlanen were taken to the U.S. to be analyzed for Pu. 2. Direct measurement of radiation in the people by gamma spectrographic analysis: To perform this analysis tons of radiation-free lead bricks were shipped to the Marshalls and a shielded counting facility set Up in one of our air-conditioned trailers and transported to Bikini on our vessel (LCU-Liktanur). The measurement of body radiation by such analysis is very sensitive and requires complex electronic equipment and scientific personnel from BNL who are experts in this technique.

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3. Personnel exposure to gamma radiation: Gamna levels on the island were derived from data furnished by radiological survey groups from the University of Washington, Lawrence Livermore Laboratory (University of Urine analyses for 90Sr and 137 Cs for personnel living at Bikini Rongelap and LTtirik for 1970-1975 are summarized in Table I and individual data are presented in Table 6. The average Sr levels over the past 5 years in the Bikini people, based on radiochemical urine analyses, were about the same as the people living on Rongelap. The average urinary Cs level was about 1/2 to 1/3 that of the Rongelap group over the same period. Gamma spectrographic data from whole body counting on several ~larshall Island groups are summarized in Table 2 and individual data for the Bikini people, whole body counted in 1974, are presented in Table 8. Based on this direct counting technique 137Cs levels of the Bikini inhabitants were about 1/4 the levels of the Rongelap people (also counted at that time). These values are well below the maximum permissible levels as stated by the ICRP*. The graphs in figures 1 and 2 show that the estimated body burdens of 90Sr (derived indirectly from urine) and the Cs (by whole body counting) for the Bikini people are well below the peak values noted in the Rongelap people. The latter group had reached a peak of 6-11% of the maximum permissible 90Sr level (for general populations) in 1961-1965.and about 22% of the Report of Committee II on Permissible Dose for Internal Radiation (1959). Internatioml Commission on Radiological Protection.

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137Cs level in about 1965. These low levels of internally absorbed radionuclides in the Bilcini people are in accord with the fact that they have been subsisting mainly on imported foods. Analyses for plutonium 239, and 240 were carried out also on many of the urine samples. No statistically significant levels of plutonium were measured (Table 7). In 1971 nasal swabs from 10 men working on Bikini (2 samples each, one from each naris) were found to have no measurable The total estimated bone marrow doses (the critical organ for somatic radiation effects) from all radiation sources for people living at Bikini, Rongelap, Utirik, Long Island, New York and Denver, Colorado are shown in (Table 3). Since the people living at Denver have a considerably higher natural radiation contribution (due to cosmic radiation) their mean exposure is substantially higher than the people living on Bikini. The mean estimated dose to people on Long Island is about half that of the people of Denver. It might be noted thar many thousands of people living in areas of South American and India are exposed to much higher levels than indicated for Bikini due to the naturally high thorium content of the soil . There have been no reports of increased cancer or other ill effects in Denver or these other populations that might be related to their increased Table 4 shows results of analyses of water samples from Bikini. Based on these findings the well water is in the permissible range of intake for each radionuclide as stated in ICRP I?ublication 2 (ref. pg. 3). Catchment Eisenbud, M. International Symposium on Areas of High Natural Radioactivity. Sunnnary Report, Pocos de Coldas, Brazil, 1975.

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(rain) water is very low in activity. Consumption of marine life offers no radiation problem. Coconut crabs (see Table 5) appear to contain high enough levels of activity to be banned from the diet. They are quite scarce in any event and represent a minor portion of their diet. Further analyses of indigenous foods (pigs, chickens, vegetables, etc.) have not been completed. However, the estimated body burdens of radionuclides resulting from the present consumption of these available local foods and including possibly some well water have been below the ICRP

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RADIOCHEMICAL ANALYSES OF URINE (DATA IN AVERAGE pCi/liter)” No. in group Av. vol. ml Av. Ca, mg/liter 9osr Analytical error terms associated with 90.Sr and 137 Cs analyses were usually less

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Mean Cesium-137 Levels Obtained by Whole Body Counting - 1974 Estimated Dose to Bone Marrow (mrem/yr) SOURCE BIKINI ENUE RONGEL4P UTIRIK DENVER LONG ISLAND Dose on Marshall Islands based on personnel and environmental data.

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Radiochemical Analyses of Well Water From Bikini (Data in pCi/liter) drinking water (camp area) 3580 Radiochemical Analyses of-Coconut Crabs From Bikini (Data in pCi wet weight)

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Individual 90Se and 137Cs levels in urine (Radiochemical Analyses Done By ERDA Health and Year Sample Vol. (ml);~ Safety Laboratory, New York, N.Y.)

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780 I For PU Analysis * Volumes less than 600 ml are almost certainly incomplete collections. Extrapolated values for small samples may be falsely higher clue to exaggeration of background Analytical error terms associated with 90Sr and 137Cs analyses were usually less than 10 percent.

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ANALYSIS FOR PLUTONIUM ON BIKINI URINE SAMPLES (pCi/1) * Volumes less than 600 ml are almost certainly incomplete collections. Extrapolated values for small samples may be falsely higher due to exaggeration of background The error in the measurement of the plutonium samples was ~ 100% which means that no statistically significant levels’ could be found. of these samples at a later date showed the error was +–lOO%.