Status Report - Dose Reassessment for Populations on Rongelap and Utirik Following Exposure to Fallout from the Bravo Incident (March 1, 1954) (Enclosure)

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DWK? Reassessment for Populations on Rongelap and Utirlk folluwlng exposu~~tLO Incidence of thyr~’idnoduJes, benign and malignant, in the expo6ed populations of Uttrik and Rongulap has indicated critical differences in correspondence between tWdUlt? incidence and thyroid dose for the populations (Table 1). The estimated external dose received from the time fallout began to the time of evacuation shows tt~~cthe Rongelap population received an external dose (175 rads) which was about IJ times chat for the Utirik population (14 rads), and the thyroid dose was abuut 10 times larger, whereas the incidence of thyroid nodules in the two pupulatlu[l~ were not significantly diiferent. A preliminary study has indicated that the critical area of investigation that could shed light i6 the period during fallout and evacuation for both the fslands. In addition, the fact that the Utirik population returned within 120 days following evacuation, whereas the Rongelap population returned only aftef three years, requires that we look closeJy at the IJtirikpopulation in terms of a longer exposure period, buch internal and external, Further studies would, therefore, have to concencracc on the reexamination of all available data in reports issued by various agencies during that period, consultations with scientific personnel involved at chat time, identifying the areas of uncertainty, and using appropriate computer programs to analyze the data. The end result will enable us to look for correlations between the incidence of thyro~d nodules ana the reassessed dose estimates. To examine the external and internal dose estimates to the Rongelap and Utirik populations fo~lowing the “Bravo” test in order to: a. Increase the confidence in the reported values b. test the hypothesis that radiation effects can be translated into meaningful dose estimates e. look for correlationship between the thyroid cancer cases and the reassessment dose estimates (if any). Method of Study: 1. Literature Search: This would require examtning the various research reports Naval Research Defense Laboratory (NRDL) Reports Reports fr~o.various other laboratories (University of Washington, etc). 2. Personnel Contdcts: Efforts will bc made to contact as many of chc scientists and technical ptrsons, who were involved In the early years for information on measurement techniques and analytical procedures.

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*(:orrec[cd for control lncldeuce. Reference B!JL-2192fJ- Summary of Thyroid Findings in Marshallese 22 Years After Exposure to

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3. Use vi iilm badge datu at Rongerik to quantify the fallout building curveupslopa aniidownmlopet and to extrapolate t,his information to Rongelap and 4. Determine the B/I ratio and thus evaluate the contri~Otion of 0 dose i:) estimating the Y depth dose; for example, the 0 activity dose due to 5* Plot all the available data on external radiation and determine decay factors. The question to be raised will be: Do the data res~lt in a curve similar to the esti~tes T-L05 relationship, or does it exhibit different values, such 6. ,, Examine the question on internal dose estimations from, urine analysis, food ingestion, inhalation and data from animal studies, In thig process all available information on diet and lifestyle would bc compiled so as to dcrlve realistic dose estimates from external and internal sources. 7, Examine ocher studies done elsewhere on ~ e thyroid nodules, for example; Lhe Chicago Group Study, and also the use of 291 to determine the early thyroid doses . Histor+ samples collected soon after fallout will be used in determining the 1291 concentrations. In addition, 95Tc would also be determined since it is known to be retained in the ~~~yroid gland. If possible, excised thyroid glands would also be stud$ed for I concentrations. 8. Use a “state-of-the-art$o compuwr simulation program to determine the transport and deposition of radioactive fallout following the BRAVOtest. This study a. plots of integrated’’ air concentration isopleths for fission products iodine, cesium and strontium b. deposition isopleths for the aforementioned fission products, plus 239Np/239PU if possible, and c. time plots of the buildup and decline of airborne fallout concentrations near sea level at the points of interest, and/or the building of ground deposited fallout. Status of Study: a. Figqre 1 shows a plot of the gamma dose rate in roentgens per hour at three feet above ground at 24 hours after the BRAVOtest explosion. Figure 2 shows the estimated total dose contours in roentgens at 96 hours after the BRAVOtest explosion indicating 175 rads of whole body gamma radiation for the Rongelap inhabitants and 14 rads for the Utirik inhabitants. In view of these observations, an exhaustive search of all reports generated Tables 2 and 3 for Rongelap and Utirik respectively. This data has been plotted in Figures 3 and 4. These plots will be further examined when results from Item 8 above will be received.

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Dose Rates Conseqwrit ‘ToThe “~ravc” Shot. Parch 1, 1954 Rongelap - 115 Miles From GZ I 80 (50) ‘ Reduction in actual 1,2*L pared to T-1*2 cume.

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Dose Rates Consequent ‘1’oThe “Bravo” Shot, March End of fallout Based on plot Eeturn to Uttrik Beturn to Utirik Based on plot

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2. Glasstone: The Effucts of Nuclear Weapons, 1957, pgs. 424, 426. Figures 4. Dr. Harley’s Letter of October 27, 1976 to Dr. Conard. 5. Plot of All Available Data - Figures I & II. 7. University of Washington Data, September 1959.

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2. Diet and Lifestyle Study All available reports concerning fallout on Allinginai\$Kongelap, Rongerik and Utirjk have been examined and pertinent lofunnation has been collated into onu location. The data collucted concer~~~ external radiation measurements, radionuclide concentration in soil, water, vegetation, animals and food items. In addition, efforts are being made to collect information on whole body analysis and bioassay samples. A recent diet and lifestyle study completed in November 1978 will provide a firm basis to estimate internal and external doses. samples are also collected by University of Washington during the have been analyzed for 1291 (Table 4), These being analyzed for 9%c. Information from item 8 (Methods of Study) will be required to correlate the findings. Additional samples from these areas (Rongelap, Ronerik, Utirik) will be analysed for 1291 and 99Tc if required. In addition, we are exploring the possibility of analyzing “Bikini-ash’’*he fallout that settled on “TlleLuckyD ragon”. This sample should provide the most accurate description of the fallout. a. All available data pertaining to meteorological conditions before, during and after the BRAVOtest have been collected and transmitted to Lawrence Llvermore Laboratory for the computer analysis. These results should be available by February/March 1979. b. A recent Marshall Islands Radiological survey completed in December 1978 should provide Iso-dose lines for recent times. Comparison of the two plots should be very valuable in assessing 1954 5. Discussionsaxe being continued with the scientists and technical people who were involved during Operation Castle.

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SOIL, (SAND, FROMBOTTWOF UELL), RONGELAPATOLL Done by PNL, Hanford, Washington OF ISLAND) RONGELAP

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FOR RONGEIAPAND UTIRIK RESIDENTS-1954 TO 1980 SAFETYAND ENVIRONMENTAL PROTECTIONDIVISION UPTON, NEW YORK 11973

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This report was prqwesf ax an acrtnsnt o! w ork qsontorrd bv an aqencv of the Uniwd States Grxernmrnt. Neither the U nimd Stws Government nor any agent} thereof. pioYcea, makes any warrantv, cxpruas or lmphecf. or wsumm anv Irqal Iiabihtv or rrtua, product, ur process dwcioard. or rcprments that i!s use would nnt infrin~c privately owned riqhw. Referrrwe herein lo anv spccdic commercial prndw. process. or service IN trade uarnr. trademark. manufac!urcr. or otherwise, tines not nercwanlv mnstnuw or implv its rndwwcmrm. rccommcndatiun. w fwrin? IW the ~ni!ed opinions of authom exprrsseti hrrcin do nut ncccxsanly $Iare or retkt those O( I he Unircd Statca Gkrvernmerrt or any aqerrcy. wn!ractor or wbconwactor thercui. Printed in the Uniwd S~alm of America National Technical Information Service

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A RECONSTRUCTIONOF CHRONIC DOSE EQUIVALENTSFOR RON(;FtLAP AND UTIRIK RESIDENTS - 1954 TO 1980 From June 1946 to August 1958, the U.S. Department of Defense Md Atomic Energy C~ission conducted nuclear weapons tests in the Northern Marshall Islands. BRAVO, an above-groundtest in the-Castleseries, resulted in radioactive fallout contaminatingRongelap and IJtirikAtolls. On March 3, 1954, the inhabitantsof these atolls were relocated until radiation exposure rates declined to acceptable levels. Environmentaland personnel radiological monitoring programs were begun in the mid 1950’s by Brookhaven National Laboratory to ensure that dose equivalents received or conauittedremained within U.S. Federal Radiation Council Guidelines for members of the general public. Body burden and dose equivalenthistories along with activity ingestion patterns post return are presented. Ibsimetric methods, results, and internal dose equivalent distributions for subgroups of the population are also described.

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On March 1, 1954, lt Bikini Atoll, BRAVO, tests in the Castle series] was detonated. The BRAVO device caused substantial surface contaminationon inhabitedatolls within a 2?000 square mile area. ‘rhc contaminated region was ci~ar shaped and included Ailinginaev Rongelap, Rongorfk, and Utirik Atolls which lay east of ground zero at distances from 60 thinned out to The fallout on Rongelap, initiallyvisible at H+6 hours, had the extent that it was no longer seen at H+1O hours (G162).” 3, 1954, the 64 residentsof Rongelap Atoll and 18 residentsof Sifo Island, Ailinginae Atoll, were evacuated. On March 3 afld4, evacuationof 157 Utirik Atoll residents also took place. During the first few weeks and at least once every year from 1957 to the present, a Brookhaven National Laboratory medical teem, organized by the Departmentof Deferiseand by the Atomic Energy Commission and its successor organizations?has provided medical examinations to monitor the heslth of the persons initiallyaffected by the fallout from the nuclear testing programs plus a comparisonpopulation. Reports of their findings The Utirikese and Rongelapese returned to their hxae atolls in June 1954 and in June 1957 respectively. The earlier repatriationof Utirik Atoll was based on the low level of external radiation exposure measured after the initial 3 month observation period (March to June 1954). The Utirik populationwas not . ceived comprehensive physical examinations. Following the 1957, medical survey, two men, removed from Utirik for medical reasons! were whole body counted at Argonne National Laboratory and provided urine samplee for radiochemicalanal-

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ysis of J37C8. hr persona vitited Argonne from Rongelep end, in addition, pooled urine samples from both atollu were a~lyzed radiochemically for and ‘“Sr. Subsequent Brookhven National Laboratoryexpeditions by nmmbers of the Medical Department and Safety and Environmental Protection Division utilized whole body counting and radiochemicalanalysis of urine and blood samples to identify and quantify the radionuclides that were,present in the body. The results of these radiological measurements are given in terms of body burden in l . Tablea 1 and 2. Throughout this paper the unita of quantities are S1 derived lnd those which lre sccepted for use with the S1 for the time being. ThU8 both the Curie and the Becquerel may be used as ~nita for the quantity activity. The lforementionedbody burden tables illustrateadult mean values for Rongelap and Utirik. An adult, aa classified here, waa a person over 16 years of age. The mean body mass in this age interval was 60 kilograms. The observed body maas versus age distribution is shown in Figure 1 for Rongelap residents. l%e same body mesa vpraus:age distribution was observed at IJtirik.., Because of the paucity of measurement at Wirikt information on 60C09 Zn, and Fe was in some instances derived from the ratio of adult mean body burdens between Rongelap and Utirik. A mean ratio of 2.6 was observed in body burdens for 65Zn, 90Sr, and 137Ca after they reached their maximum values. The deviation of this ratio was 15%. the following analysis, personal in conjunctionwith contemporary body burden histories and residence indosimetric models, are used to estimate internal dose. and a sumnary of the provided for various Dosimetric distributionswere constructed from the results derived activity ingestion rates and dose equivalents was subgroups of the population. Additionally,exposure rate history curves were constructed for each atoll for the period following the

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Body -9s MU*CC Body mlobcr Days Foot 6urdea Ot 6urd9n of Burden of Mturn 0 l bcto derived body burdxm

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FifJ. 1 Body Mass as a Function of Age for Residents of Rongelap Atoll

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pattern models, provided an estimate of external dose equivalent. Exponentially declining activity concentrations have been observed in surface soil for 137 C@, 1291, and 90 Sr from 1954 to the present on Rongelap and Utirik Atolls. Declining activity concentrations have also been observed in vegetation at a rate greater than that predicted by radioactive decay. Thu; exponential decline in dietary lctivity WaS assumed and the foLlowinf3 general equations were derived.

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time post onset of uptake, days? instantaneous fraction of atoms decaying per unit time, day -1 initial atom ingestion rate, atoms day-l, the number of fraction of atoms removed from compartment i by atoms in compartment i relative to the number in all compartments at the onset of declining continuous uptake! (t=O)j GI tract to blood, fraction excreted by the urine pathway? instantaneous fraction of atoms removed or added to the atom uptake per unit time, day‘1, due to factors other than radioactive decay, instantaneous body burden, Bq, body burden at the onset of uptakej Wj the number of disintegrations in all compartments occurring during the uptake interval, Bq days. The development of Eqs. (l), (2), and (3) was based on the following convolution integral. At acme variable time, T, defined during a fixed uptake . interval, T, the daily activity ingestion rate crossing the gastrointestinal. tract to blood is given by

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The wholt body zetentiou lt any ti~ t-T of the fraction of initial radio~:tivity Thus, the instantaneous activity at time t+ that remains following input during It follows that the instantaneous activity at time t+ that remains following input during T is The solutiom of the user defining t. additional fixed post the iotegral yields l general expression that depends on For example, if t is the fixed uptake interval, T, plus an As previously stated, Eq. (2) lpplied at Rongelap and Utirik, it was for the situation that variable time t was the uptake interval. Additionally, persona who returned to the atolls in June 1954 and June 19S7 did so with an initial body burden$ q“. The behavior of this contribution to was used to relate ?

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urine lctivity concentration to body burden. Equation 3 was obtained by Equation. (1) and (2) were used to determine atoms removed or added to the atom uptake per unit the instantaneous fraction of tial daily activity ingestion rizte required to produce the measured or derived body burden. Equation (3) was used to determine the number of disintegrations that occurred in the body during the residence internal of an individual living on Rongelap or Utirik Atoll. If the mean residence time in the diet is much much longer than the reuidence interval, then constant continuous uptake is achievedo. Equations (1) and -A l Single uptake expressions are obtained by setting ~ lqual to zero. In some cases only radioactive decay may ruiuove the nuclide from dicta’ry items; for these cases % would equal zero, In the caue of the former Bikini residents, the maturing of coconut trees during residence on Bikini Atoll caused a continuously increaai~ dietary uptake of 137 Cs. Thus, KE was found to have a negative value. In the case of Eongelap and Utirik, Kg was ‘found to have a positive value for Cs …