RADIO LOG CAL CONDTONS AT B KIN ATOLL: PROSPECTS FOR … · Atoll (the remainder were conducted at...
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RADIO LOG CAL CONDTONS AT B KIN ATOLL: PROSPECTS FOR RES LEMENT
Transcript of RADIO LOG CAL CONDTONS AT B KIN ATOLL: PROSPECTS FOR … · Atoll (the remainder were conducted at...
RADIO LOG CALCONDTONS
AT B KIN ATOLL:PROSPECTS FOR
RES LEMENT
RADIOLOGICAL CONDITIONSAT BIKINI ATOLL:
PROSPECTS FOR RESETTLEMENT
The following States are Members of the International Atomic Energy Agency:
AFGHANISTANALBANIAALGERIAARGENTINAARMENIAAUSTRALIAAUSTRIABANGLADESHBELARUSBELGIUMBOLIVIABOSNIA AND
HERZEGOVINABRAZILBULGARIACAMBODIACAMEROONCANADACHILECHINACOLOMBIACOSTA RICACOTE D'lVOIRECROATIACUBACYPRUSCZECH REPUBLICDEMOCRATIC REPUBLIC
OF THE CONGODENMARKDOMINICAN REPUBLICECUADOREGYPTEL SALVADORESTONIAETHIOPIAFINLANDFRANCEGABONGEORGIAGERMANYGHANAGREECEGUATEMALAHAITI
HOLY SEEHUNGARYICELANDINDIAINDONESIAIRAN, ISLAMIC
REPUBLIC OFIRAQIRELANDISRAELITALYJAMAICAJAPANJORDANKAZAKHSTANKENYAKOREA, REPUBLIC OFKUWAITLATVIALEBANONLIBERIALIBYAN ARAB JAMAHIRIYALIECHTENSTEINLITHUANIALUXEMBOURGMADAGASCARMALAYSIAMALIMALTAMARSHALL ISLANDSMAURITIUSMEXICOMONACOMONGOLIAMOROCCOMYANMARNAMIBIANETHERLANDSNEW ZEALANDNICARAGUANIGERNIGERIANORWAYPAKISTANPANAMA
PARAGUAYPERUPHILIPPINESPOLANDPORTUGALQATARREPUBLIC OF MOLDOVAROMANIARUSSIAN FEDERATIONSAUDI ARABIASENEGALSIERRA LEONESINGAPORESLOVAKIASLOVENIASOUTH AFRICASPAINSRI LANKASUDANSWEDENSWITZERLANDSYRIAN ARAB REPUBLICTHAILANDTHE FORMER YUGOSLAV
REPUBLIC OF MACEDONIATUNISIATURKEYUGANDAUKRAINEUNITED ARAB EMIRATESUNITED KINGDOM OF
GREAT BRITAIN ANDNORTHERN IRELAND
UNITED REPUBLICOF TANZANIA
UNITED STATESOF AMERICA
URUGUAYUZBEKISTANVENEZUELAVIET NAMYEMENYUGOSLAVIAZAMBIAZIMBABWE
The Agency's Statute was approved on 23 October 1956 by the Conference on the Statute of the IAEAheld at United Nations Headquarters, New York;
it entered into force on 29 July 1957. The Headquarters of the Agency are situated in Vienna. Its principal objective is"to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world".
© IAEA, 1998
• Permission to reproduce or translate the information contained in this publication may be obtained by writing to the Division of Publications,International Atomic Energy Agency, Wagramerstrasse 5, P.O. Box 100, A-1400 Vienna, Austria.
Printed by the IAEA in AustriaMarch 1998
STI/PUB/1054
RADIOLOGICAL ASSESSMENT REPORTS SERIES
RADIOLOGICAL CONDITIONSAT BIKINI ATOLL:
PROSPECTS FOR RESETTLEMENT
INTERNATIONAL ATOMIC ENERGY AGENCYVIENNA, 1998
VIC Library Cataloguing in Publication Data
Radiological conditions at Bikini Atoll : prospects for resettlement. •—Vienna : International Atomic Energy Agency, 1998.
p.; 29 cm. — (Radiological assessment reports series, ISSN 1020-6566)STI/PUB/1054ISBN 92-0-100398-6Includes bibliographical references.
1. Nuclear weapons—Bikini Atoll (Marshall Islands)—Testing.2. Environmental impact analysis—Bikini Atoll (Marshall Islands).3. Bikinians—Relocation. 4. Radiation dosimetry. I. InternationalAtomic Energy Agency. II. Series.
VIOL 98-00184
FOREWORD
At the present time there are many locations around the world affected by radioactive residues. Some arethe result of past peaceful activities, such as the processing of radium for use in medicine and luminizing, andthe mining of uranium and other ores. Others result from activities during the Cold War, for example, residuesfrom arms production activities and from the testing of nuclear weapons. With the improvement of relationsbetween the major countries in the world and stimulated by the new and general concern about the state of theenvironment, attention in many countries has turned to remediating the areas affected by radioactive residues.
Some of the residues from uranium mining and weapons testing are located in countries where there isan absence of the infrastructures and expertise necessary for evaluating the significance of the radiation risksposed by the residues and for making decisions on remediation. In such cases, governments have felt it necessaryto obtain outside help; in other cases, it has been considered to be socially and politically necessary to haveindependent expert opinions on the radiological situation caused by the residues. As a result, the IAEA hasbeen requested by the governments of a number of Member States to provide assistance in this context. Theassistance has been provided by the IAEA in relation to its statutory obligation "to establish...standards ofsafety for protection of health...and to provide for the application of these standards...".
The present assessment was requested by the Government of the Republic of the Marshall Islands withinwhose territory there are residues of nuclear weapon testing conducted over a 13 year period immediatelyfollowing the Second World War. The Marshall Islands Government wished to have an independent view of thesituation in order to provide a basis for a decision on whether the former inhabitants of Bikini Atoll shouldbe permitted to return to their home island. For this purpose the IAEA convened a meeting of internationalexperts chaired by K. Lokan of Australia in December 1995 to review the available information on the subject.Subsequently, and at the request of the Government of the Marshall Islands, the radiological data which formedthe technical basis for the conclusions were corroborated through a monitoring mission to Bikini Island conductedby an IAEA team in May 1997. This report is issued in the Radiological Assessment Reports Series.
EDITORIAL NOTE
Although great care has been taken to maintain the accuracy of information contained in this document, neitherthe IAEA nor its Member States assume any responsibility for consequences which may arise from its use.
The use of particular designations of countries or territories does not imply any judgement by the IAEA as to thelegal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries.
The contributors to drafting are responsible for having obtained the necessary permission for the IAEA to reproduce,translate or use material from sources already protected by copyright.
CONTENTS
1. SUMMARY 1
1.1. Preamble 11.2. Conclusions 11.3. Addendum 2
2. THE MARSHALL ISLANDS 3
2.1. Bikini Atoll 3
3. BACKGROUND: NUCLEAR WEAPON TESTING IN THEMARSHALL ISLANDS AND ITS AFTERMATH AT BIKINI ATOLL 6
3.1. Nuclear weapon tests 63.2. Evacuation of the population from Bikini Atoll 63.3. Suspension of testing 63.4. Restoration and resettlement 73.5. Radiological reassessment 73.6. Second relocation 83.7. Further radiological reassessments 83.8. Attempted rehabilitation 83.9. Nationwide radiological reassessment 83.10. Request for an international review 8
4. THE INTERNATIONAL REVIEW 9
4.1. Objectives of the review 94.2. Technical framework 94.3. Concerns of the Bikinian people 94.4. Undertaking of the IAEA 9
5. RADIOLOGICAL CONCEPTS IN THE CONTEXTOF NUCLEAR WEAPON TESTING 11
5.1. Radiological quantities and units 115.2. Radiological impact of atmospheric nuclear weapon test explosions 135.3. Health effects of radiation exposure 16
6. PRESENT ENVIRONMENTAL RADIOLOGICAL CONDITIONSAT BIKINI ATOLL 18
6.1. Activity in soil 186.2. Activity in foodstuffs 186.3. Activity in air (resuspension) , 196.4. Activity in the lagoon 196.5. Rates of absorbed dose in air 24
7. ESTIMATES OF POTENTIAL RADIATION DOSES TO PEOPLERESETTLING BIKINI ISLAND UNDER PRESENT CONDITIONS 26
7.1. Sources and pathways of exposure 267.2. Doses due to natural sources 267.3. Doses due to residues from nuclear weapon testing 26
8. RADIATION PROTECTION CRITERIA 31
8.1. Protection against radiation 318.2. International radiation safety standards 318.3. Activities involving radiation exposure 318.4. Practices 318.5. Interventions 328.6. The situation at Bikini Atoll 328.7. Intervention situations 328.8. Generic intervention level 338.9. Generic guidance for rehabilitation of areas of chronic exposure 36
9. HABITABILITY OF BIKINI ISLAND 38
9.1. Radiological assumptions 389.2. Possible remedial measures 399.3. Conditions for habitability 429.4. Activity levels in foodstuffs 42
10. CONCLUSIONS AND RECOMMENDATIONS 43
REFERENCES 45
ADDENDUM: IAEA CORROBORATORY MONITORING MISSIONTO BIKINI ISLAND 49
A-l. Introduction 49A-2. Measurement programme 50A-3. Results and discussion 52A-4. Conclusions 53
CONTRIBUTORS TO DRAFTING AND REVIEW 67
1. SUMMARY
1.1. PREAMBLE
An international Advisory Group met at IAEAHeadquarters in Vienna on 11-15 December 1995for the purpose of reviewing the current radiologi-cal conditions at Bikini Atoll, Republic of the Mar-shall Islands, and advising on the prospects for reha-bilitation of the atoll and resettlement of its indige-nous population. The Advisory Group was convenedby the IAEA in response to a request for techni-cal assistance from the Government of the MarshallIslands within the framework of IAEA technical co-operation project MHL/9/003, 'Radiological Moni-toring in Bikini Atoll'.
Tests related to nuclear weapons were carriedout in the territory of the Marshall Islands between1946 and 1958. In this period, 23 such tests, witha total yield equivalent to around 70 million tonnesof trinitrotoluene (TNT), were performed at BikiniAtoll (the remainder were conducted at EnewetakAtoll). The population of Bikini Atoll, at that time167 people, was evacuated before the testing wasbegun and could not return owing to the residualradioactive materials remaining in the atoll as a resultof the fallout from the explosions. The Bikinian pop-ulation, which has since grown significantly, is nowmainly residing on the island of Kill and on the islandof Ejit in Majuro Atoll, far away from Bikini Atoll.
Since the testing was terminated, a number ofassessments have been made of the radiological con-ditions at Bikini Atoll, including a nationwide studycommissioned by the Government of the MarshallIslands.1 Over the years, the Bikinian people receiveddiffering advice on the feasibility of resettling theiratoll. The Marshall Islands — which in 1994 becamea Member State of the IAEA — turned to the IAEAfor confirmation, requesting a peer review of the var-ious assessments made of the radiological conditionsat Bikini Atoll and of the recommendations made forits rehabilitation.'
1 In July 1997, the official journal of the Health PhysicsSociety, 'Health Physics', devoted a special edition to the 'Con-sequences of Nuclear Weapons Testing in the Marshall Islands'.Fifteen of the papers contained in this edition are relevant tothe subject of this report and to the history of health physicsstudies related to Bikini Atoll.
The IAEA has a statutory responsibility toestablish standards for protection against radiationexposure, and its Statute also authorizes its Secre-tariat to provide for the application of the standardsupon the request of a Member State. While the IAEAstandards are established for the peaceful uses ofnuclear energy, their basic protection criteria can alsobe applied in principle to the particular radiologicalsituation at Bikini Atoll.
The primary aim of this review was to assistthe Bikinian people to form their own judgement onthe radiological conditions at their atoll and on theprospects for resettling there, should they so desire.At the meeting, the Advisory Group benefited greatlyfrom the participation of a delegation from the Mar-shall Islands.
At the request of the Government of the Mar-shall Islands, the international review was limitedto Bikini Atoll and did not extend to other atolls,islands and islets affected by radioactive fallout fromthe testing. Moreover, within Bikini Atoll, it was con-centrated on Bikini Island, where the Bikinian popu-lation formerly resided.
The review relates to the prevailing radiologicalcircumstances and their implications for the futurehabitability of the atoll. It is not intended to includethe retrospective assessment of the past radiologicalimpact of nuclear testing. The United Nations Scien-tific Committee on the Effects of Atomic Radiation(UNSCEAR) has routinely estimated, and reportedto the United Nations General Assembly, radiationlevels and effects attributable to nuclear weapon test-ing — including the tests carried out in the territoryof the Marshall Islands. Some of the UNSCEAR esti-mates have been included in the report, but only forthe sake of completeness.
1.2. CONCLUSIONS
Important conclusions of the review are that"no further independent corroboration of the mea-surements and assessments of the radiological con-ditions at Bikini Atoll is necessary", but that "theBikinian community might be reassured about theactual radiological conditions at Bikini Atoll bya limited programme of monitoring of radiation
levels there, which should involve some participationof members of the community."
On the basis of the information provided forthe review it is concluded that "permanent resettle-ment of Bikini Island under the present radiologicalconditions without remedial measures is not recom-mended in view of the radiation doses that couldpotentially be received by the inhabitants from a dietof entirely locally produced foodstuffs." However, itis noted that "in practice, doses caused by a diet oflocally derived foodstuffs are unlikely to be actuallyincurred under the current conditions, as the presentMarshallese diet contains — and would in the nearfuture presumably continue to contain — a substan-tial proportion of imported food which is assumed tobe free of residual radionuclides." Thus it is concludedthat "provided certain remedial measures are taken,Bikini Island could be permanently reinhabited."
Two types of remedial measures were consi-dered in detail, namely the use of potassium fertilizerto limit the uptake of caesium — the main chem-ical element in the residual radionuclides at Bikini— and a comprehensive surface soil scraping strat-egy. In this context the following conclusions werereached: "While no definite recommendations aregiven on which strategy to follow, it is consideredthat the strategy using potassium fertilizer is thepreferred approach" and "the results expected fromthe strategy using potassium fertilizer are consistentwith international guidance on interventions to avoiddoses in chronic exposure situations and, therefore,the strategy would provide a radiologically safe envi-ronment permitting early resettlement." Moreover,"the alternative strategy, i.e. soil scraping — statedto be the alternative preferred by the Bikinian people— would be very effective in avoiding doses caused bythe residual radionuclides, but it could entail seriousadverse environmental and social consequences."
On the assumption that the proposed strategyis undertaken, it is further recommended that "regu-lar measurements of activity in local foodstuffs shouldbe made to assess the effectiveness of the measurestaken" and that "a simple local whole body monitorand training in its use should be provided as a fur-ther means of enabling potential inhabitants to sat-isfy themselves that there is no significant uptake ofcaesium into their bodies."
Should the Bikinians decide to resettle BikiniIsland after taking the recommended remedial mea-sures, the radiation doses for the people living onthe island would be higher than the doses prevailingbefore the testing started and also than the global
average doses due to natural sources of radiation.However, total doses will still be lower than naturalbackground radiation doses in large areas of the worldwhere many people lead healthy lives. Moreover, peo-ple inhabiting Bikini Island could be assured thattheir radiation doses would be acceptable in terms ofinternational standards and that their health wouldbe adequately protected against radiation exposuredue to the residual radioactive materials at BikiniAtoll.
1.3. ADDENDUM
This report was presented to and discussedwith the late President of the Republic of the Mar-shall Islands, His Excellency Amata Kabua, whowas accompanied by the Honourable Thomas Kijiner,then the Republic's Minister of Health and Environ-ment, during the President's official visit to Tokyoon 14 October 1996. Immediately after this, on17 October 1996, the report was formally submittedto the Government of the Marshall Islands in Majurothrough the requesting office, the Ministry of ForeignAffairs. The report was also presented to the Bikiniancommunity through the Office of the Local Govern-ment of Kili/Bikini/Ejit in Majuro on 18 October1996. The report was finally officially accepted by theGovernment of the Republic of the Marshall Islandsthrough a letter from its Ambassador to the UnitedStates of America on 18 September 1997.
At the meeting on 14 October 1996, Presi-dent Kabua suggested that an independent corrobo-ration by IAEA experts of the available environmen-tal data relating to the residual radioactive materialson Bikini Island, which had served as the basis for thereport's assessment, would be desirable. It had beenconcluded that no further independent corroborationof the measurements and assessments of the radiologi-cal conditions on Bikini Atoll was necessary. However,taking into account the need for the Bikinians to bereassured about the situation, the IAEA agreed tocarry out the requested corroboratory monitoring.
Therefore, an IAEA environmental monitoringteam carried out a limited programme of environmen-tal measurements and sampling during the period7-22 May 1997. Measurements were made of theabsorbed dose rate in air and of the concentrationof the most radiologically significant radionuclides inrepresentative soil and foodstuff samples on BikiniIsland. The results obtained by the IAEA monitoringteam provided good corroboration of earlier measure-ments made by other expert teams and are attachedto the report as an Addendum.
2. THE MARSHALL ISLANDS
The Republic of the Marshall Islands (seeFig. 1) consists of two archipelagic island chainsof 29 atolls (Ailinginae, Ailinglaplap, Ailuk, Arno,Aur, Bikar, Bikini, Ebon, Enewetak, Erikub, Jaluit,Knox, Kwajalein, Lae, Likiep, Majuro, Maloelap,Mili, Namorik, Namu, Rongelap, Rongerik, Taka,Taongi, Ujae, Ujelang, Utirik, Wotho and Wotje) andfive separate reef islands (Jabat, Jemo, Kill, Lib andMejit), comprising 1152 islands and islets in total.Kwajalein is the largest of the group — indeed, thelargest atoll in the world. The islands are situatedsome 4000 km southwest of Honolulu, about halfwaybetween Hawaii and Papua New Guinea, in tropi-cal waters of the northern Pacific Ocean, north ofthe equator and west of the international date line,between latitudes 4° and 15° N and longitudes 161°and 173° W. The land area adds up to only 181 km2,but the total sea territory is vast, stretching over3000 km between its northwestern and southwest-ern extremes. The capital is Majuro, in Majuro Atoll,towards the southeast.
There is evidence that the Marshall Islandshave been populated for almost 4000 years. Theindigenous inhabitants are mainly Micronesian, pri-marily of Australoid and Polynesian descent. Theislanders speak two major Marshallese dialects fromthe Malayo-Polynesian family. The official languageis English, which is universally spoken. The currentpopulation is about 56 000, with nearly half living inMajuro. It is a young and fast growing population:more than half of the Marshallese are under 14 yearsold and the population growth rate is nearly 4% peryear, with a birth rate of around 4.6% per year, adeath rate of around 0.75% and a total fertility rateof nearly seven children on average born per woman.
Agriculture and tourism are the mainstays ofthe Marshallese economy. Agricultural production isconcentrated in small farms. The main commercialcrops are coconuts, tomatoes, melons and breadfruit,and there is some pig raising. Small scale indus-try is limited to handicrafts, fish processing andcopra, the dried coconut flesh from which coconutoil is extracted, which is the main export productof the islands. More recently, there have been plansto exploit phosphate resources. The islands have fewnatural resources and are occasionally subject to
typhoons. Land and fresh water are highly valuedresources; in addition to the Republic's small landarea, the supply of potable water is inadequate. Sincethe average height above sea level of the islands isonly about two metres, the possibility of global cli-mate changes and potential rises in sea levels consti-tute a major issue for the Republic.
The Marshall Islands derive their name fromCaptain William Marshall, a British sea captain ofthe East India Company, who sailed through theislands in the 1780s. However, the archipelago wasnever formally a British colony. In 1885, Germanydeclared the islands a German protectorate. WhenJapan entered the First World War in 1914, theislands fell to Japan. After the war, the whole ofMicronesia, including the archipelago, was mandatedto Japan by the League of Nations.
In the Second World War, the Marshall Islandsarchipelago came under the military control ofthe USA. In 1947, the islands came under thetrusteeship of the USA as part of the Trust Ter-ritory of the Pacific Islands, which also includedthe Caroline Islands and the Mariana Islands. TheMarshall Islands became self-governing in 1979, witha constitution, a president and an elected legislature('Nitejela') in Majuro. Each atoll sends at least onedelegate (senator) to the Nitejela. A Compact of FreeAssociation with the USA came into effect in 1986.The trusteeship of the USA was formally dissolvedby the United Nations Security Council in 1990 andthe Republic of the Marshall Islands was admitted tothe United Nations in 1991. The Republic became aMember State of the IAEA in January 1994.
2.1. BIKINI ATOLL
Bikini Atoll, located 850 km northwest ofMajuro on the northern fringe of the Marshall Islandsand remote from the other atolls, comprises morethan 23 islands and islets. Bikini, Eneu, Nam andEnidrik Islands account for over 70% of the land area.Bikini and Eneu are the only islands of the atoll thathave had a permanent population. Most of the atoll'sother islands are rather small or narrow, and also tendto be infertile, prone to storms and swept by sea water
in high winds and high seas. Besides Bikini and Eneu,only Aerokojlol and Jelete Islands have edible crops,mainly coconut.
In 1946, Bikini Atoll was the first site in theMarshall Islands used for nuclear weapon testing.Prom 1948, Enewetak Atoll, a neighbouring atoll,replaced Bikini Atoll as the test site. From 1954,Bikini Atoll was reactivated as a test site untilnuclear weapon testing was terminated in the Mar-shall Islands in 1958.
The Bikinians have their own dialect ofMarshallese and are seen as a distinct Marshallesepopulation. Before nuclear weapon testing started,the population of Bikini Atoll — at that time 167 peo-ple — was evacuated and resettled, first on RongerikAtoll and eventually on the isolated island of Kili,about 800 km southeast of Bikini Atoll. Some werethen resettled on the island of Ejit in the MajuroAtoll. They continue to live on these two islands. ACouncil of the Kili/Bikini/Ejit local government rep-resents them in Majuro.
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3. BACKGROUND:NUCLEAR WEAPON TESTING IN THE MARSHALL ISLANDS
AND ITS AFTERMATH AT BIKINI ATOLL
3.1. NUCLEAR WEAPON TESTS
Bikini and Enewetak Atolls were used as sitesfor tests related to nuclear weapons by the USAbetween 1946 and 1958.2 Bikini Atoll was the site of23 of the 66 tests conducted under water, at groundlevel and above ground in the Marshall Islands. Theyields of the tests at Bikini Atoll amounted to about72% of the total yield of 1.1 x 105 kilotonnes (kt) ofTNT equivalent for both test sites [1].
Testing at Bikini Atoll started with 'OperationCrossroads' in 1946. This experiment staged by theUS Navy, which included the so-called 'Able' and'Baker' shots, involved 242 ships, 156 aircraft andmore than 42 000 military and civilian personnel,and used more than 5000 experimental animals. PromJuly 1946, Bikini Atoll remained inactive as a test siteand tests were conducted on Enewetak Atoll in 1948,1951 and 1952. Then, in February 1954, Bikini Atollwas reactivated as a test site with the 'Castle' seriesof tests. They continued in 1956 with the 'Redwing'series and were terminated in 1958 with the 'Hard-tack I' series. The tests of highest yield were those inthe 'Castle' series, which included the 'Bravo' shot, athermonuclear device of 15 megatonnes (Mt) equiva-lent yield of TNT.
Table I presents data for the trials at BikiniAtoll (see also Refs [2-7]). Figure 2 shows approxi-mately where in Bikini Atoll the nuclear devices weredetonated [3-5].
3.2. EVACUATION OF THE POPULATIONFROM BIKINI ATOLL
Prior to the Able test in 1946, the first nucleartest in Bikini Atoll, the 167 Bikinians then living onBikini Island were evacuated to Rongerik Atoll, about
2 A few of the nuclear weapon tests in the Pacific Oceanwere conducted by the USA outside the Marshall Islands, nearJohnston Atoll and Christmas Island (the latter Kiribati, for-merly the Gilbert Islands); however, these tests were limitedto high altitude explosions.
200 km to the east, seemingly to reside there untilan unspecified future date when the testing wouldbe completed. (Knowledge at that time about thelong term consequences of radioactive fallout and thetransfer of radionuclides through the food chain waslimited.) The Bikinians remained on Rongerik Atollfor a period of two years. In 1948, they were movedbriefly to Kwajalein Atoll and later in the same yearto Kill, a small (0.8 km2) isolated island. Kili Islandis fertile, with rich soil, but is less than half the sizeof Bikini Island. It has no lagoon, no protective reefand no fishing grounds. The small beach is frequentlysubject to high waves. The Bikinians saw the moveto Kili as a temporary relocation and were reluctantto change from being fishermen to being farmers.
3.3. SUSPENSION OF TESTING
Nuclear weapon testing in the Marshall Islandswas terminated in July 1958. On 31 October 1958,the USSR, the United Kingdom and the USA sus-pended atmospheric nuclear weapon testing underan international moratorium. The Treaty BanningNuclear Weapon Tests in the Atmosphere, in Outer
Nam Odrik
AdrikanJelete
Lukoj
Legend:— Reef~ Island
Lpmihk _ _Aornen 0 1 2 3
Nautical miles (NM)
BikiniBokantaukLomelenEnealoRojkereBokonjeblEneu
ATest site 'A1
Sunkenships
CV/
H AerokojlolBikdrin
FIG. 2. Locations of nuclear weapon test detonations atBikini Atoll (1NM=1.85 km).
TABLE I. NUCLEAR WEAPON TESTS CONDUCTED AT BIKINI ATOLL
Test series
CrossroadsCrossroadsCastleCastleCastleCastleCastleRedwingRedwingRedwingRedwingRedwingRedwingHardtack IHardtack IHardtack IHardtack IHardtack IHardtack IHardtack IHardtack IHardtack IHardtack I
Shot name
AbleBakerBravoRomeoKoonUnionYankeeCherokeeZuniFlatheadDakotaNavajoTewaFirNutmegSycamoreMapleAspenRedwoodHickoryCedarPoplarJuniper
Date
30 June 194624 July 194628 February 195426 March 1954
6 April 195425 April 19544 May 1954
20 May 195627 May 195611 June 195625 June 195610 July 195620 July 195611 May 195821 May 195831 May 195810 June 195811 June 195827 June 195829 June 19582 July 1958
12 July 195812 July 1958
Type
Air dropUnderwaterSurfaceBargeSurfaceBargeBargeAir dropSurfaceBargeBargeBargeBargeBargeBargeBargeBargeBargeBargeBaf'geBargeBargeAir burst
Yield(kt TNT
equivalent)
2323
1500011000
1106900
1350038003500
3651 100450050001360
25.192
213319412
14220
930065
Mapreference
(see Fig. 2)
AABBCDDECFFDGBHBIBIHBJH
Space and Under Water was signed in Moscow on5 August 1963.3
3.4. RESTORATION AND RESETTLEMENT
In August 1968, following a number of radio-logical surveys [8] that had been carried out since1958 to assess the impact of the USA's programmeof nuclear weapon testing, President Lyndon John-son publicly announced that Bikini Atoll was safefor habitation and approved the resettlement of theBikinian people on the atoll. Prom February to Octo-ber 1969, the atoll was cleared of debris. Fruit trees,including coconut, breadfruit, pandanus, papaya andbanana, were replanted. A further radiological surveyof Bikini Atoll was carried out in 1970.
Initially, in 1970, three Bikinian families andabout 50 Marshallese workers returned to theatoll. Eventually, 139 Bikinians would resettle there.
3 A comprehensive ban on nuclear weapon testing wasadopted by the United Nations General Assembly in Septem-ber 1996.
However, the Bikinian people remained unconvincedof the safety of the atoll, and in 1975 they initi-ated a lawsuit against the Government of the USAto terminate the resettlement effort until a satisfac-tory and comprehensive radiological survey had beencarried out.
3.5. RADIOLOGICAL REASSESSMENT
In 1975, a further radiological assessment ofBikini Atoll was conducted [9]. However, at that timethe trees planted in 1969 had not yet grown to matu-rity and few samples were available for reliable esti-mates to be made of radionuclide concentrations infood crops. In 1976, an external radiation survey pro-gramme for five northern atolls, which included somemeasurements at Bikini, was conducted. A continu-ing sampling and analytical programme was begunat Bikini Atoll in 1978 to gather additional dataas a basis for more precise radiation dose estimatesfor the residents of Bikini and Eneu Islands. Radio-anthropometry (whole body radiation measurements)
for the purpose of estimating the intake of radio-active materials by Bikinian residents had begun inApril 1977.
In 1978, it was determined that for the inhab-itants of Bikini Atoll a tenfold increase in the bodycontent of the radionuclide 137Cs had occurred [10].This increase was the result of a combination of thecoconut trees starting to bear fruit and a droughtthat led to increased consumption of coconut fluidfor want of fresh water. Apart from assessments ofthe long term impacts on the Bikinians, studies havebeen conducted on service personnel and Japanesefishermen exposed, in particular, as a consequence ofthe Castle Bravo test [11-14].
3.6. SECOND RELOCATION
In August and September 1978, in response tothe high uptake of caesium in the population — thencomposed of the 139 Bikinians who had returned toBikini Atoll — officials of the Trust Territory decidedto relocate the Bikinians again from their atoil, backto Kili Island and to Ejit Island at Majuro Atoll.
3.7. FURTHER RADIOLOGICALREASSESSMENTS
At the time of the second relocation, a newradiological survey in 11 northern atolls of the Mar-shall Islands, sponsored by the USA (Departmentof Energy), was started. The survey used detectorsmounted in helicopters which were flown in parallelflight lines in order to plot external gamma dose ratecontours [15]. Also, samples of vegetation, marinefoods, animals and soil were collected and analysed[16, 17]. Revised radiation dose evaluations were pub-lished in 1980 and 1982 [18, 19] which indicatedthat — should the Bikinians decide to resettle theirisland — the terrestrial food chain would be the mostsignificant exposure pathway. This dose assessmentwas most recently updated in 1995 on the basis ofa continued measurement programme at the atoll[20, 21]. Additional information on radiological sur-veys is reported in Ref. [22].
3.8. ATTEMPTED REHABILITATION
The Congress of the USA created a 'Resettle-ment Trust Fund for the People of Bikini Atoll' forthe purpose of improving living conditions on Kili. Italso set up the 'Bikini Atoll Rehabilitation Commit-tee' to study and report on the feasibility and cost
of rehabilitating the atoll. In 1984, this Committeeissued its first report, stating that Bikini could beresettled provided that no locally grown foodstuffsor groundwater would be consumed. The Committeealso considered other courses of action, including theremoval of topsoil from the islands.
In January 1986, a Compact of Free Associationbetween the Governments of the USA and the Mar-shall Islands was signed into law. This provided forthe payment of compensation to the people of Bikini,Rongelap, Enewetak and Utirik Atolls. An additionaltrust fund was established for the cleanup and reset-tlement of Bikini Atoll.
3.9. NATIONWIDE RADIOLOGICALREASSESSMENT
A separate radiological assessment — theRepublic of the Marshall Islands Nationwide Radio-logical Study (NWRS) — was commissioned by theGovernment of the Republic of the Marshall Islands.By this means, Bikini Atoll, as well as all other atollsin the Republic, was to be monitored for radioactiveresidues. Oversight was provided by a Scientific Advi-sory Panel of well known and respected scientists [23].Laboratory quality control programmes were imple-mented to ensure that the NWRS surveys could pro-vide accurate measurements. In general, the studyconfirmed the findings of earlier measurement pro-grammes. The findings of the NWRS were publishedand a report on Bikini Atoll was released in Febru-ary 1995 [1, 24]. In August 1995, six months after theNWRS issued its report on Bikini Atoll, the Nitejelaof the Marshall Islands considered the NWRS find-ings but did not accept them.
3.10. REQUEST FOR ANINTERNATIONAL REVIEW
The Republic of the Marshall Islands wasaccepted as the 122nd Member State of the IAEAon 26 January 1994. The Marshall Islands Govern-ment subsequently requested the IAEA to conductan independent international review of the radio-logical conditions at Bikini Atoll, and to considerand recommend strategies for the resettlement of theatoll. The IAEA responded to this request by con-vening an Advisory Group, which met in Viennaon 11-15 December 1995. The Group was con-vened under the framework of IAEA technical co-operation project MHL/9/003, 'Radiological Moni-toring in Bikini Atoll'.
4. THE INTERNATIONAL REVIEW
4.1. OBJECTIVES OF THE REVIEW
There were three main objectives of the inter-national review:
— To assess the radiological conditions on BikiniAtoll in the Republic of the Marshall Islands, tak-ing into account the information submitted bythe Republic's government;
— To ascertain whether any corroboration of theavailable information on the current radiologicalconditions at the atoll is needed;
— To determine whether any intervention to takeremedial actions for the purpose of radiation pro-tection is required and, if so, the form, scale andduration of such an intervention.
4.2. TECHNICAL FRAMEWORK
The framework for the review were the inter-agency 'International Basic Safety Standards forProtection against Ionizing Radiation and for theSafety of Radiation Sources' (the 'Basic Safety Stan-dards'). The Basic Safety Standards are jointly spon-sored by the Food and Agriculture Organization ofthe United Nations (FAO), the IAEA, the Inter-national Labour Organisation (ILO), the NuclearEnergy Agency of the Organisation for EconomicCo-operation and Development (OECD/NEA), thePan American Health Organization (PAHO) andthe World Health Organization (WHO). They wereissued by the IAEA as Safety Series No. 115 [25] in1996. The Basic Safety Standards were mainly usedto establish the radiation protection criteria (see Sec-tion 8) for judging the prospects for resettlement ofthe Bikinian people in their homeland.
The international review took full account ofall the available data from the Republic of the Mar-shall Islands NWRS [1], as well as of a large num-ber of assessments made by scientists from aroundthe world, mainly from Lawrence Livermore NationalLaboratory (LLNL), USA,4 and to some extent from
the Forschungszentrum fur Umwelt und Gesundheit(GSF), Germany.5
4.3. CONCERNS OF THE BIKINIAN PEOPLE
The sentiments and concerns of the Bikinianswere presented by Senator Henchi Balos, their electedrepresentative for the past 16 years to the MarshallIslands Nitejela [27]. One of their major fears is arecurrence of the events of the late 1960s. At thattime, advice was given by scientists in the USA thatBikini Atoll was safe for habitation; however, eightyears later the inhabitants were informed that theyhad ingested amounts of 137Cs far in excess of theexpectations of the scientists and that they had to berelocated from the atoll.
Prior to 1978, communication with the Bikini-ans about the potential hazards associated withradiation exposure was reportedly sparse and unin-formative. Although the population has grown con-siderably, there is no individual from the communitywith expertise in matters relating to radiation. TheBikinians have come to consider peer review by inde-pendent scientists as crucial to their acceptance ofthe findings of scientific studies. Their representativesexpressed their appreciation at the formation of theinternational Advisory Group.
Senator Balos said that children everywhereplay in the dirt and that "this is why we have saidthat the soil in the village must be scraped". Forthose areas of Bikini Atoll which may not be scraped,the representative voiced the continuing fear aboutthe radioactive "poison" in the soil. Moreover, thecommunity fears that no one will assume responsibil-ity for the continued application of countermeasuresintended to reduce the uptake of radionuclides intofood crops.
4.4. UNDERTAKING OF THE IAEA
The Director General of the IAEA, Hans Blix,addressing the Advisory Group and the Bikinian
4 The assessments made by LLNL were submitted byW.L. Robison.
5 The assessments made by GSF were submitted byH. Paretzke [26].
delegation [28], reviewed the various locations aroundthe world which during the arms race had been sitesfor the testing of nuclear devices. In addition tothe Marshall Islands, these locations include Alge-ria, Australia, China, Kazakhstan, Mururoa and Fan-gataufa Atolls in French Polynesia, the Russian Fed-eration and the USA.
Mr. Blix observed that, although the worldwas hopeful that a comprehensive nuclear test bantreaty would soon be achieved, there were some con-sequences of past nuclear testing that remained to be
dealt with. Moreover, many people as a result con-tinued to feel fear, resentment and a sense of injury,and were looking for answers about their healthand safety in the future and the health of theirenvironment.
The Director General noted that it was a dutyof the IAEA to provide technical assistance to theMarshall Islands, now a Member State. Furthermore,he reiterated the IAEA's commitment to helping theMarshall Islands and other areas of the world to dealwith residual radionuclides in the environment.
10
5. RADIOLOGICAL CONCEPTS IN THE CONTEXT OFNUCLEAR WEAPON TESTING
This section provides the context for the follow-ing sections on assessment of the radiological condi-tions at Bikini Atoll by introducing the most impor-tant radiological concepts, quantities and units usedin the report — where the term radiological is usedto mean radiation related — by providing a sum-mary of the releases of radioactive materials and sub-sequent worldwide radiation exposures that resultedfrom global atmospheric nuclear weapon testing, andfinally by briefly describing the health effects that canbe caused by exposure to ionizing radiation.6
5.1. RADIOLOGICAL QUANTITIESAND UNITS
Radiation is the transport of energy throughspace. In traversing material, radiated energy isabsorbed. In the case of ionizing radiation, which isthe type of radiation of current concern in relationto nuclear weapon testing in the Marshall Islands,the absorption process consists in the removal of elec-trons from the atoms, producing ions. Ionizing radi-ation (hereinafter referred to as radiation) is inher-ent in the universe. It originates from the cosmos; itis also produced in manufactured devices such as Xray tubes; and it results ubiquitously from the disin-tegration of radioactive atoms of matter (or radio-nuclides) — the phenomenon that is called radio-activity. Radionuclides occur naturally; they may alsobe produced artificially, for instance in nuclear explo-sions such as those with which this report is con-cerned. As the radionuclides disintegrate, they trans-form into other (radio-)nuclides. The time requiredfor the transformation of one half of the atoms of theradionuclide concerned is a constant usually termedthe half-life of the radionuclide.
The Basic Safety Standards have adopted theinternational system of radiation quantities and unitsrecommended by the International Commission onRadiation Units and Measurements (ICRU). Themain physical quantities of the system are the activ-
ity, or rate of nuclear transformation of radionuclidesemitting radiation, and the absorbed dose, or energyabsorbed per unit mass of matter from the radiationto which it is exposed. Thus:7
— The activity of a radioactive material is the num-ber of nuclear disintegrations of radionuclideswithin that material per unit time; the unit ofactivity being the reciprocal second, termed thebecquerel (Bq);
— The absorbed dose is the mean energy impartedby ionizing radiation to matter per unit mass; theunit of absorbed dose being the joule per kilo-gram, termed the gray (Gy).
Although the absorbed dose is the basic physi-cal dosimetric quantity, it is not entirely satisfactoryfor radiation protection purposes since the effective-ness of radiation in damaging human tissue differsfor different types of ionizing radiation. Consequently,the absorbed dose averaged over a tissue or organis multiplied by a radiation weighting factor to takeaccount of the effectiveness of the given type of radia-tion in inducing health effects. The resulting quantityis termed the equivalent dose.
The quantity equivalent dose is used when indi-vidual organs or tissues are irradiated. However, thelikelihood of injurious late effects owing to a givenequivalent dose differs for different organs and tissues.Consequently, when the whole body is irradiated, theequivalent dose to each organ and tissue must be mul-tiplied by a tissue weighting factor to take account ofthe differing radiosensitivities of different organs ofthe body. The sum total of such weighted equivalentdoses for all exposed tissues in an individual is termedthe effective dose.
The unit of equivalent dose and that of effec-tive dose is the same as that of absorbed dose, namelythe joule per kilogram (or gray), but the term siev-ert (Sv) is used in order to avoid confusion with the
6 This information has been derived from the Basic SafetyStandards [25] and the latest UNSCEAR reports [29, 30].
7 Since the becquerel is a unit expressing a very small activ-ity, the following multiples are used in this report: 1000 Bq orkilobecquerel (kBq); 1 million Bq or megabecquerel (MBq);1 x 109 Bq or gigabecquerel (GBq); 1 X 1012 Bq or terabec-querel (TBq); 1 x 1015 Bq or petabecquerel (PBq); 1 x 1018 Bqor exabecquerel (BBq).
11
TABLE II. NUMBER AND YIELD OF ATMOSPHERIC NUCLEAR EXPLO-SIONS FOR WEAPON TESTING: WORLDWIDE AND AT BIKINI ATOLL
Worldwide Bikini Atoll
Year(s)
1945-1951
1952-1954
1955-1956
1957-1958
1959-1960
1961-1962
1963
1964-1969
1970-1974
1975
1976-1980
1981-
Number
26
31
44
128
3
128
0
22
34
0
7
0
Estimated yield(Mt)
0.8
60
31
81
0.1
340
0.0
12.2
12.2
0.0
4.8
0.0
Number Estimated yield(Mt)
2 0.05
5 46.5
6 18.2
10 12
No further tests
unit of absorbed dose. This report commonly usesthe millisievert (mSv), a subdivision of the sievertwhich is equal to a thousandth of a sievert. (For thepurpose of comparison, the average annual individualeffective dose that the world's population incurs as aresult of exposure to cosmic rays and radiation arisingfrom naturally radioactive materials in the biosphereis about 2.4 mSv.)
In general, unless otherwise stated, the termdose is used in this report to mean effective dose whenit refers to the whole body or equivalent dose whenit refers to body organs.
When radionuclides are taken into organs ofthe human body, the resulting dose is received bythe exposed individual throughout the period of timeduring which their activity continues in the body. Thecommitted dose is the total dose delivered during thisperiod of time, and is calculated as a specified timeintegral of the rate of receipt of the dose. Dose assess-ments in this report are based on the committed dosefrom the intake.
Nuclear weapon test explosions in the atmo-sphere introduced time elements that made the sourceof radiation different from previously known sourcesin the sense that, although the period of practice waslimited, the period of exposure has been very pro-tracted. After each test, some long lived radionuclides
were released which will persist in the biosphere formany years, causing radiation exposure to future pop-ulations. Therefore, to quantify the situation moreprecisely, UNSCEAR introduced the concept of dosecommitment, defined as the integral over infinite timeof the per caput dose rates delivered to the world'spopulation as a result of a specific nuclear explosionor series of explosions. The exposure is presumed tooccur over a period of many years after the explosionshave taken place and the individuals who are pre-sumed to receive the resulting doses therefore includethose not yet born at the time of the explosions.
The total impact of the radiation exposuredue to a given practice or event, such as nuclearweapon testing, depends on the number of individualsexposed and on the doses they receive. The collectivedose, defined as the summation of the products ofthe mean dose in the various groups of exposed peo-ple and the number of individuals in each group, maytherefore be used to characterize the radiation impactof a practice or event. The unit of collective dose isthe man-sievert (man-Sv).
The old units of activity, absorbed dose and(equivalent and effective) dose are the curie (Ci), radand rem, respectively, which have the following equiv-alences: 1 Ci = 3.7 x 1010 Bq; 1 rad = 0.01 Gy;and 1 rem = 0.01 Sv. These old units and their
12
TABLE III. ACTIVITY OF RADIONUCLIDES RELEASED AND GLOBALLYDISPERSED BY ATMOSPHERIC NUCLEAR EXPLOSIONS
Estimated activity (excluding local fallout)
Normalized release
(PBq/Mt) Total activity
i, loiaiu.Liui'.iJ.u
3H14Cb54Mn55Fe89Sr9°Sr91y
95Zr103Ru106Ru125Sb131j
137Cs140Ba141Ce144Ce239Pu240pu
241pu
12.32 a5730 a312.5 d2.74 a
50.55 d28.6 a
58.51 d64.03 d39.25 d371.6 d2.73 a8.02 d30.14 a12.75 d32.50 d284.9 d24 100 a6560 a14.4 a
Fission Fusion
0.026 740b 0.67
— 15.9— 6.1590 —3.90 —748 —922 —1540 —76.4 —3.38 —4200 —5.89 —4730 —1640 —191 —— —— —— —
From worldwidetesting(EBq)
2400.225.22
91.40.60411614323811.8
0.524651
0.91273225429.6
0.006520.00435
0.142
From testing inBikini Atoll
(EBq)a
33.60.030.730.2812.80.0816.220.033.31.650.0791.10.1310335.64.14
< 0.001< 0.001
0.02
a Based on a fission/fusion yield ratio of 0.14. Since the yield ratio for the Bikini tests is unknown,it is assumed in this table that the same fission/fusion ratio applies at Bikini Atoll as fortotal worldwide atmospheric testing of nuclear weapons.
b For simplicity, it is assumed that all 14C is due to fusion.
submultiples (millicurie, microcurie, picocurie; mil-lirad, microrad; millirem and microrem) are widelyused in the reports on the radiological conditions atBikini Atoll.
5.2. RADIOLOGICAL IMPACT OFATMOSPHERIC NUCLEAR WEAPONTEST EXPLOSIONS
5.2.1. Releases of radionuclidesto the environment
Nuclear explosions in the atmosphere were car-ried out at several sites, mostly located in the north-ern hemisphere, between 1945 and 1980. The periodsof most active testing were 1952-1958 and 1961-1962.
In all, 520 tests were carried out, with a total fis-sion and fusion yield of 545 Mt. The number andyield of worldwide atmospheric nuclear explosionshave been estimated by UNSCEAR and are summa-rized in Table II, together with data for tests under-taken in Bikini Atoll.
Since the Treaty Banning Nuclear WeaponTests in the Atmosphere, in Outer Space and UnderWater was signed in Moscow on 5 August 1963, mostnuclear test explosions have been conducted under-ground. Some gaseous radionuclides were uninten-tionally vented during a few underground tests, butthe available data are insufficient to allow an assess-ment of the radiological impact. The total explosiveyield of the underground tests is estimated to havebeen 90 Mt, much smaller than that of the earlieratmospheric tests. Although most of the underground
13
TABLE IV. DOSE COMMITMENT AND COLLECTIVE DOSE TO THE WORLD'SPOPULATION FROM ATMOSPHERIC NUCLEAR WEAPON TESTING
Radionuclide
Dose commitment (mSv)
Prom all tests From tests at Bikini Atolla
Collective effective dose (man-Sv)
Prom all tests From tests at Bikini Atoll
14C
137Cs90Sr95Zr106Ru54Mn144Ce131,.3H95 Nb125Sb239pu
140Ba241 Am103Ru240pu
55Fe241pu
89Sr91 Y141Ce238pu
Total (rounded)
2.58b
0.470.110.090.070.060.050.050.050.040.030.020.020.020.010.010.0080.0050.0030.0030.0010.0013.7
0.360.070.020.010.010.0080.0070.0070.0070.0060.0040.0030.0020.0020.0020.0020.0010.0010.00050.00050.00010.00010.52
25 800 0001 890 000
435 000278 000222 000189 000181 000165 000164 000131 0008800058000530005100041 00039000260001700011000890047002300
30 000 000
3 612 000265 000609003890031 100265002530023 1002300018300123008 12074207140574054603640238015401250
660320
4 180 000
a Based on a fission/fusion yield ratio of 0.14. Since the yield ratio for the Bikini tests is unknown, it is assumedin this table that the same fission/fusion ratio applies at Bikini Atoll as for total worldwide atmospherictesting of nuclear weapons.
b For simplicity, it is assumed that all 14C is due to fusion.
debris remains contained, it is a potential source ofhuman exposure. Underground nuclear weapon test-ing has never been conducted in the Marshall Islands.The earlier atmospheric tests, including those under-taken in Bikini Atoll, remain the principal source ofworldwide exposure due to nuclear weapon testing.Table III shows UNSCEAR's estimates of the activ-ity of radionuclides released and globally dispersed inall atmospheric nuclear testing and of those releasedin tests undertaken at Bikini Atoll.
The radioactive debris from an atmosphericnuclear test is partitioned between the local groundor water surface and tropospheric and stratosphericregions, depending on the type of test, location andyield. The subsequent precipitation or falling out ofthe debris is termed local fallout when it is locallydispersed, and tropospheric fallout and stratosphericfallout when it is globally dispersed.
Local fallout can comprise as much as 50%of the production for surface tests and includeslarge radioactive aerosol particles which are depositedwithin about 100 km of the test site. The northernislands of Bikini Atoll were severely contaminated bylocal radioactive fallout, and concentrations of 137Csand 90Sr remain relatively high, together with lesseramounts of 239+240pu and 24iAm
Tropospheric fallout consists of smaller aerosolswhich are not carried across the tropopause afterthe explosion and which deposit with a mean resi-dence time of up to 30 days. During this period thedebris becomes dispersed, although not well mixed,in the latitude band of injection following trajecto-ries governed by wind patterns. From the viewpointof human exposures, tropospheric fallout is impor-tant for nuclides with a half-life of a few days to twomonths, such as 131I, 140Ba or 89Sr.
14
TABLE V. COLLECTIVE DOSE COMMITMENT BY THE WORLD'SPOPULATION FOR CONTINUING PRACTICES AND FORSINGLE EVENTS
Collective doseSource Basis of commitment (million man-Sv)
Natural sources
Medical exposureDiagnosisTreatment
Nuclear weapon testing
Current rate for 50 years
Current rate for 50 years
Completed practice(all nuclear weapon tests)
Completed practice(nuclear weapon tests atBikini Atoll)
650
9075
30
4.2
Nuclear power
Severe accidentsOccupational exposure
MedicalNuclear powerIndustrial usesDefence activitiesNon-uranium mining
Total (all occupations)
Total practice to dateCurrent rate for 50 years
Events to dateCurrent rate for 50 years
0.42
0.6
0.050.120.030.010.4
0.6
Stratospheric fallout, which comprises a largepart of the total fallout, is from those particles whichare carried to the stratosphere and later give riseto worldwide fallout, the major part of which isin the hemisphere of injection. Stratospheric falloutaccounts for most of the worldwide residues of longlived fission products. Exposure of humans to fall-out activity consists of internal irradiation (inhalationof radioactive materials in surface air and ingestionof contaminated foodstuffs) and external irradiationfrom radioactive materials present in surface air ordeposited on the ground.
5.2.2. Radiation exposures
The contributions of the radionuclides releasedby atmospheric nuclear testing to the total dose com-mitment and the collective dose to the world's pop-ulation have been estimated by UNSCEAR and arereported in Table IV, together with the contributionfrom testing undertaken at Bikini Atoll.
The summary in Table IV shows that the longlived radioisotope 14C is the dominant contributor to
the total effective dose commitment, accounting for70% of the effective dose commitment to the world'spopulation. However, if only 10% of the 14C dosecommitment is included in the comparison, i.e. if thedose commitments are truncated approximately tothe year 2200, by which time all other radionuclideswill have delivered effectively all of their doses, 14Ccontributes only 19% to the truncated effective dosecommitted to the world's population.
The dose commitment to the world's popu-lation over infinite time from all atmospheric test-ing is about 3.7 mSv. The contribution from thetests undertaken at Bikini Atoll is about 0.5 mSv.Both figures are comparable to the effective dosefrom a single year of exposure to natural sources ofradiation.
The total collective effective dose to be hypo-thetically incurred by the world's population over aninfinite time period, attributable to the full seriesof atmospheric tests of nuclear weapons, is approx-imately 30 million man-Sv, of which about 4 millionman-Sv are attributable to tests undertaken at BikiniAtoll. About one quarter of the collective dose will
15
have been delivered by the year 2200; the remainder,due to 14C, will be delivered over approximately thenext 10 000 years. In comparison, the global collectivedose attributable to natural sources over 50 years is650 million man-Sv.
Some further perspective on these figures isprovided in Table V. Although atmospheric test-ing of nuclear weapons represents the human-madesource resulting in the largest collective dose, this isconsiderably smaller than the collective dose deliv-ered unavoidably in a lifetime by exposure to naturalbackground radiation.
These global estimates include a contributionfrom the doses to people close to the sites used foratmospheric tests. Although this contribution is smallin global terms, some local doses have been substan-tial. The thyroid equivalent doses to children near theNevada test site in the USA may have been as high as1 Sv and it has been reported that thyroid equivalentdoses to some children in Utah may have been as highas 4 Sv [31]. Similar high thyroid doses were incurredbetween 1949 and 1962 in settlements bordering theSemipalatinsk test site in the former USSR. Groundactivity near Maralinga, Australia, the site of nucleartests carried out by the United Kingdom, has beensufficient to restrict subsequent access. Some indi-vidual doses in the Marshall Islands were also high,mainly due to the Bravo test in 1954 and because thewind turned towards inhabited islands following theexplosion.
The Bravo test is now widely known to havecaused significant human radiation exposures atatolls east of Bikini [12, 13]. Owing to a sudden andunusual change in the wind direction on the day ofthe test, predominantly from the west rather thanthe east, people were exposed to radiation on at leastthree atolls: Rongelap, Ailinginae and Utirik. In par-ticular, high radiation doses were received by theinhabitants of Rongelap Island (about 210 km fromBikini Atoll) and by some Rongelap Islanders tem-porarily residing on Ailinginae Atoll (about 150 kmaway). Lesser doses were received by the people ofUtirik Atoll (about 570 km away). The other testshad no comparable radiological consequences.
Eighty-two individuals were evacuated fromRongelap 51 hours after the explosion and 159 per-sons were removed from Utirik within 78 hours. Effec-tive doses as a result of external exposures, mainlyfrom short lived radionuclides, ranged from 1.9 Svon Rongelap (67 persons, including three in utero)and 1.1 Sv on nearby Ailinginae Atoll (19 persons,including one in utero) to 0.1 Sv on Utirik Atoll
(167 persons, including eight in utero) [32]. The col-lective effective dose was of the order of 160 man-Sv.Equivalent doses to the thyroid, caused by several iso-topes of iodine and tellurium and by external gammaradiation, were estimated to be 12, 22 and 52 Sv onaverage and 42, 82 and 200 Sv maximum to adultsand children of 9 years and 1 year, respectively, onRongelap Island [32].
The people of Bikini Atoll, while relocated onKill, were not exposed to local fallout but mainlyto the stratospheric fallout resulting from nuclearweapon testing in different parts of the northernhemisphere, including the Marshall Islands.
5.3. HEALTH EFFECTS OFRADIATION EXPOSURE
It has been recognized since the time of thefirst studies on X rays and radioactive minerals thatexposure to radiation at high levels can cause earlyclinical damage to the tissues of the human bodywhich, if extremely severe, can lead to death. Inaddition, long term epidemiological studies of pop-ulations (both human and animal) exposed to radia-tion, particularly the survivors of the atomic bomb-ing of Hiroshima and Nagasaki in Japan in 1945, havedemonstrated that exposure to radiation also has apotential for the delayed (or late) induction of malig-nancies and, plausibly, for hereditary effects.
5.3.1. Early effects
Exposure leading to very high radiation dosescan cause effects such as nausea, reddening of the skinor, in severe cases, more acute syndromes that areclinically expressed in exposed individuals within ashort period of time after the exposure. These effectscan be clinically diagnosed in the exposed individ-ual and attributed to the individual's dose. They arecalled deterministic effects because they are certain(predetermined) to occur if the dose exceeds a thresh-old level. Deterministic effects are the result of var-ious processes, mainly cell death and impaired celldivision, caused by exposure to radiation. If theseprocesses are extensive enough, they can impair thefunction of the exposed tissue. The higher the dose isabove the threshold for the occurrence of a particu-lar deterministic effect in an exposed individual, themore severe is the effect. The threshold dose levelsdepend on the type of effect, the organ affected andalso the duration of exposure. For doses delivered in
16
a short period of time, deterministic effects can beexpected at equivalent doses of the order of 1000 mSv.Death caused by acute radiation syndrome may occurat an effective dose of several thousand millisieverts.
The levels of equivalent doses and effectivedoses from the residual radionuclides from pastnuclear weapon testing to be expected at present inBikini Atoll (see Section 7) would be far below thethreshold levels for the deterministic effects and nohealth effects of this type could conceivably occur inpeople living there now.
5.3.2. Late effects
As already stated, radiation exposure canalso induce effects, such as malignancies, which areexpressed after a relatively long latency period. Also,experimental studies in animals and plants haveshown hereditary effects from radiation. Althoughhereditary effects have not been observed in humans,it is considered prudent for the purposes of settingstandards to assume that they do occur. These radi-ation induced malignancies and hereditary effects aretermed stochastic effects because of their aleatoryand probabilistic nature. The induction of stochasticeffects is assumed to take place over the entire rangeof doses, without a threshold level. Under certain con-ditions, primarily of relatively high doses and/or largenumbers of people exposed, stochastic effects may beepidemiologically detectable in the exposed popula-tion as an increase in their natural incidence.
Stochastic effects may ensue if an irradiatedcell is modified rather than killed. It is presumed
that modified somatic cells may, after a prolongedprocess, develop into a cancer. If the cell modified byradiation exposure is a germ cell, whose function isto transmit genetic information to progeny, it is con-ceivable that hereditary effects of various types maydevelop in the descendents of the exposed individ-ual. The body's repair and defence mechanisms makestochastic effects a very improbable outcome in thecase of small doses; nevertheless, there is no evidenceof a threshold level of dose below which stochasticeffects cannot result from radiation exposure. Theirprobability of occurrence is higher for higher doses;however, the severity of any stochastic effect that mayresult from irradiation is independent of the dose sus-tained. Thus, the likelihood of stochastic effects ispresumed to be proportional to the dose received,without a dose threshold. The proportionality fac-tor is known as the nominal probability coefficientfor the stochastic effect. For radiation protection pur-poses, the International Commission on RadiologicalProtection (ICRP) has recommended the use of thefollowing nominal probability coefficients within thewhole population: for fatal cancers, 5% per sievert,or 5 in 100 000 per millisievert; for non-fatal cancers,1% per sievert, or 1 in 100 000 per millisievert; andfor severe hereditary effects, 1.3% per sievert, or 1.3in 100 000 per millisievert.
Stochastic effects attributable to the residualradionuclides in Bikini Atoll may theoretically occurin a population exposed to these radionuclides. How-ever, because of the relatively low level of doses tobe expected (see Section 7) and the small size of thepopulation, any such effects would be undetectable.
17
6. PRESENT ENVIRONMENTAL RADIOLOGICALCONDITIONS AT BIKINI ATOLL
The significant residual radionuclides from thenuclear tests that remain in the soil and surroundingsof Bikini Atoll are 137Cs, 90Sr, 239+240pu and MI Am_They are found to varying degrees in both the terres-trial and marine environments. Although this sectionrefers to the radiological conditions in the whole ofBikini Atoll, it concentrates on Bikini Island, whichwas the previous permanent habitation of those peo-ple who were evacuated. It should be noted, how-ever, that all the islands of Bikini Atoll have beenthoroughly investigated, in particular in the NWRS[1] and by LLNL [33]. The results of measurementsare available, in addition to Bikini Island, for theislands of Eneu, Rochikarai, Romurikku, Vorikku,Yurochi, Nam, Chieerete, Rukoji, Enidrik, Eniman,Reere, Bigiren and Airukiraru. Moreover, the NWRSinvestigated all atolls and reef islands in the MarshallIslands and found that Bikini Island has the highestresidual activity of 137Cs.
6.1. ACTIVITY IN SOIL
The coral soil of Bikini Atoll is composedmostly of calcium carbonate (CaCOs), with somemagnesium carbonate (MgCOs) and essentially noclay. The soils are highly alkaline, with a potentialof hydrogen (pH) ranging from 7.7 to 9.0. The sur-face horizons are high in organic matter (as much as14%), although the organic matter in the soils dropsmarkedly with depth in the soil column. As a result,most of the natural nutrients and the water retentioncapacity of the soil are confined to the top 25-40 cmof the soil column. The soils are low in exchangeablepotassium (generally less than 50 parts per million)and marginal in phosphorus and trace mineral con-tent. Some native plant species and most introducedspecies show definite signs of potassium deficiency.In fact, most introduced food crops and ornamentalplants show very limited growth without the additionof potassium, phosphorus and trace minerals.
The unique composition of coral soil, which isprimarily CaCOs with no clay, produces a pattern ofavailability to plants of 137Cs and 90Sr very differentfrom that for which most data are reported in the lit-
erature, which correspond to aluminium silicate claysoils, as found in the Americas and Europe.
Bikini Island, the primary island for habita-tion at Bikini Atoll, has the highest concentrationsof 137Cs per unit mass of soil and vegetation in theatoll. The average 137Cs concentration varies over aconsiderable range between the atoll's islands. Theaverage 137Cs concentration in soil and vegetation onEneu Island, the other main island of residence, isabout 10-13% of that of Bikini Island. Nam Island,one of the two other islands large enough for possibleresidence, has a 137Cs concentration in soil of about70% of that of Bikini Island; the 137Cs concentrationin soil at Enidrik Island, the other large island, isabout 15% of that of Bikini Island.
The concentrations of transuranic radionuclides(239+240pu and 241 Am) and their ratios to concentra-tions of 137Cs and 90Sr vary around the atoll, reflect-ing the difference in the design of the nuclear devicesused in the detonations near the various islands. Theconcentrations of transuranic radionuclides in the soilon Nam Island exceed those on Bikini Island, whilethose on Enidrik Island are somewhat lower thanthose on Bikini Island. In general, the radionuclideconcentrations decrease rapidly with depth in thesoil column, although there are exceptions in partsof some islands. The activities of radionuclides perunit dry weight of soil in Bikini Island are shown inTable VI [20].
6.2. ACTIVITY IN FOODSTUFFS
Samples of various locally available foods andwater have been collected and analysed in severalstudies for their content of residual radionuclides.Table VII presents the activity per unit mass of137Cs in these foodstuffs, measured as part of theNWRS [1] and other studies [20]. The activity wasassessed from direct measurements on foodstuffswhere this was feasible; otherwise they were predictedfrom concentration ratios at locations for which therewere no measurements. The highest 137Cs concentra-tions we're found in coconut and some other fruitssuch as pandanus and breadfruit. It should be noted
18
TABLE VI. MEDIAN (AND MEAN) ACTIVITIES'1 OF 137Cs, 90Sr, 239+240pu
AND 241Am PER UNIT DRY WEIGHT OF SOIL ON BIKINI ISLAND (Bq/g) [20]
Soil depth(cm)
Interior of island0-55-10
10-1515-2525-4040-60
0-40
Village area0-55-10
10-1515-2525-4040-60
0-40
137Cs
2.3 (3.0)1.2 (1.8)0.58 (1.0)0.19 (0.48)0.071 (0.19)0.018 (0.019)
0.70 (0.91)
1.2 (2.0)1.0 (1.6)0.81 (1.2)0.53 (1.0)0.18 (0.80)0.028 (0.23)
0.67 (1.1)
90Sr
1.7 (2.1)2.0 (2.4)1.5 (2.3)0.73 (1.4)0.47 (0.77)0.32 (0.65)
1.1 (1.5)
1.0 (2.0)1.2 (2.0)1.5 (1.7)0.90 (1.6)0.62 (1.7)0.32 (1.2)
1.6 (1.5)
239+240 pu
0.32 (0.42)0.29 (0.44)0.15 (0.34)0.053 (0.16)0.0081 (0.061)0.011 (0.035)
0.17 (0.21)
0.20 (0.40)0.30 (0.40)0.22 (0.28)0.14 (0.25)0.064 (0.25)0.0058 (0.11)
0.24 (0.29)
241 Am
0.26 (0.30)0.19 (0.27)0.081 (0.18)0.026 (0.11)0.012 (0.051)0.017 (0.073)
0.11 (0.14)
0.11 (0.22)0.13 (0.20)0.12 (0.19)0.064 (0.15)0.059 (0.13)0.012 (0.11)
0.13 (0.17)
Decay corrected to 1999. The numbers in parentheses are the arithmetic mean.
that the 137Cs concentration data in the tables wererecorded over different periods of time by differentresearchers, and this explains some of the variabil-ity in the data, mainly of a statistical nature. Allsurveys have undergone quality control programmesand inter-laboratory comparisons, and therefore the137Cs data are reasonably consistent.
Activities per unit mass of foodstuff for 90Sr,239+240pu and 241 Am are provided in Tables VIII, IXand X. The 90Sr activities are less than 10% of therespective 137Cs activities in the relevant foodstuffs.The 239+240pu and 241 Am activities are even lowerthan the 90Sr activities in the relevant foodstuffs.
6.3. ACTIVITY IN AIR (RESUSPENSION)
Of the residual radionuclides present in soil,those of greatest potential significance for the inhala-tion exposure pathway are 239+240pu and 241Amincorporated into surface soil particles which can beresuspended by wind action. A detailed resuspensionstudy was made at Bikini Atoll in 1978 [34, 35]. Addi-tional work on resuspension has subsequently beencompleted at Rongelap and Enewetak Atolls. Theresults are similar at all the atolls: the average resus-pension of the surface soil is very low, with resuspen-sion factors (i.e. the relation between the activity per
unit volume of air and the activity per unit area ofsurface soil giving rise to it) ranging from 10~10 to10~n m"1. A mass loading model has been devel-oped from the data generated in these studies andused in conjunction with the 239+240pu and 241Amconcentrations in the surface soil (0-5 cm) to estimatethe daily inhalation of the two radionuclides [35]. Onthe basis of the measured activities of these radio-nuclides in the soil and the resuspension factorsmentioned above, the air concentrations of theseradionuclides are expected to be very low, and conse-quently the expected contribution to doses from radi-ation exposure via inhalation pathways is judged tobe insignificant.
6.4. ACTIVITY IN THE LAGOON
The residual radionuclides 137Cs, 90Sr,239+240pu and 241 Am are present in the atoll's lagoon,mainly in sediments, but also in water and in biota.In general, radionuclide concentrations in the lagoonsediments are about one order of magnitude higherin the northeastern, northern and northwestern partsof the atoll than in sediments in the southern halfof the atoll. Additional information on levels anddistribution of activity in Bikini lagoon sediment canbe found in Refs [36, 37],
19
TABLE VII. ACTIVITY*1 OF 137Cs PER UNIT WET WEIGHT OF LOCAL (BIKINIAN) FOOD (Bq/g)
Food type
Reef fishTuna (pelagic fish)Mahi mahiMarine crabs (shellfish)LobsterClamsTrochusIridacna muscleJedrulCoconut crabsLand crabsOctopusTurtleChicken muscleChicken liverChicken gizzardPork musclePork kidneyPork liverPork heartBird muscleBirds' eggsChicken eggsTurtle eggsPandanus fruitPandanus nutsPandanus^BreadfruitBreadfruitCoconut fluidCoconut fluidb
Coconut milkTuba/jekeroDrinking coconut meatDrinking coconut meatb
Copra meatSprouting coconutMarshallese cakePapayaSquashPumpkinBananaArrowroot (cooked)CitrusRainwaterGroundwaterb
Well waterMaloloCoffee/tea
Mean
2.9 x HP3
4.5 x ID"3
4.5 x 10"3
1.4 x 10"3
1.4 x 10-3
<4.6 x 10~4
<4.6 x 10~4
<4.6 x 10"4
<4.6 x HT4
3.7 xlO"1
3.7 xlO-1
1.8 x HP3
<2.8xlQ-4
1.5 xlO"1
1.5 xlO-1
7.0 x 10°6.5 x 10°3.6 x 10°4.2 x 10°
< 2.5 xlO-3
6.7 x 10~4
<2.8xlO"4
3.9 x 10°3.9 x 10°7.4 x 10°3.8 x 10"1
4.7x10°1.2 x 10°6.2 xlO'15.4 x 10°5.4 x 10°2.9 x 10°4.1x10°5.4 x 10°5.4 x 10°5.4 x 10°2.2 x 10°1.2x10°1.2x10°1.8 xlO-1
5.4 x 10~2
1.2 xlO-1
4.3 x 10~5
l.lxlO~s
4.5 x ID"3
4.3 x 10~5
4.3 x 10~5
Median
1.4 x ID"3
4.6 x 10"3
4.6 x 10"3
9.4 x 10"4
9.4 x ID"4
< 2.1 xlO-4
<2.1xlO"4
<2.1xlO"4
< 2.1 xlO-4
3.2 x ID"1
3.2 x ID"1
1.8 x 10"3
<2.8xlO"4
1.5 xlO"1
1.5 xlO"1
1.5 xlO-1
7.4 x 10°5.0 x 10°3.1 x 10°2.7 x 10°
< 1.4 xlO-3
6.7 x 1Q-4
1.5 x 10-1
<2.8xlO"4
3.2 x 10°3.2 x 10°7.4 x 10°3.1 x 10"1
7.1x10-*9.6 x 10- 1
4.6X10'15.4 x 10°5.4 x 10°2.6 x 10°2.4 x 10°5.4 x 10°5.4 x 10°5.4 x 10°8.2 x ID"1
5.9 x ID"1
5.9 x 10"1
1.5 x 1Q-1
6.7 x ID"2
1.2 x ID"1
3.3 x 10"5
l.lxlO'3
3.1 x ID"3
3.3 x 10"5
3.3 x 1Q-5
SD
3.1 x ID"3
2.9 x 10-3
1.3 x HT3
< 4.0 xlO-4
2.2 x 1Q-1
3.8 x 10-4
< 2.7 xlO-4
0.0 x 10°1.5 x 10"1
4.4 x 10°4.4 x 10°3.3 x 10°4.6 x 10°
<3.5xlO~3
0.0 x 10°1.5 x 10"1
3.3 x 10°
2.2 x 1Q-1
8.9 x 10"1
2.2 x 10°
3.5 x 10°
2.9 x 10°1.4 x 10°
1.1 x KT1
2.2 x 10-2
0.0 x 10°4.7 x 10~5
3.4 x HT3
Minimum
4.4 x 10~5
1.2 x 10~3
3.2 x ID"4
< 8.3 xlO~ s
1.4 x 10"1
1.6 x 10~3
<8.9xlO"5
1.5 x ID"1
2.2 x 10°1.8 x 10°1.0 x 10°2.3 x HP1
< 3.0 xlO-4
6.7 x MT4
1.1 x ID"1
9.0 x 10~2
2.8 x 10~2
1.4 xlO"1
7.2 x 10~2
8.1 x HT2
6.3 x 10~2
3.3 x 1Q-2
2.8 x ID"2
1.2 x 10"1
6.8 x 10-6
9.1 x 10-4
Maximum
1.2 x 10~2
9.6 x ID"3
4.0 x 10-3
<1.1 x 10~3
6.7 xlO-1
2.1 x 10~3
<4.7xlO~4
1.5 x 10"1
1.3 x 10+1
1.3 x 10+1
9.2 x 10°1.2 x 10+1
< 1.2 xlO-2
6.7 x!0~4
1.9 x 10+1
1.1 x 10°
6.1x10°
1.6 x 10+1
2.2 x 10+1
1.4 x 10+1
5.9 x 10°
4.7 xlO"1
6.7 x 10-2
1.2 xlO"1
2.0 x 10~4
1.5 x 10-2
Ref. [20]except where
stated
I1]
11]
W
m
W
a Decay corrected to 1999.b Data in italics are from Ref. [1].SD: standard deviation.
20
TABLE VIII. ACTIVITY* OF 90Sr PER UNIT WET WEIGHT OF LOCAL (BIKINIAN) FOOD (Bq/g) [20]
Food type
Reef fishTuna (pelagic fish)Mahi mahiMarine crabs (shellfish)LobsterClamsTrochusTridacna muscleJedrulOctopusTurtleChicken muscleChicken liverChicken gizzardPork musclePork kidneyPork liverPork heartBird muscleBirds' eggsChicken eggsTurtle eggsPandanus fruit-Pandanus nutsBreadfruitCoconut fluidCoconut milkDrinking coconut meatCopra meatSprouting coconutMarshallese cakePapayaSquashPumpkinBananaArrowroot (cooked)CitrusRain waterWell waterMaloloCoffee/tea
Mean
4.5 x 1(T5
5.3 x 1<T6
5.3 x 1(T6
<8.9xl(T6
<8.9 x 1(T5
<8.7xl(T5
<8.7xl(Ts
<8.7x 1(T6
<8.7x 1(TS
4.5 x 10~5
4.5 x 1(T5
1.5 x 10~3
1.5 x 1CT3
1.5 x 1(T3
1.5 x 10~3
6.2 x 1(T3
2.9 x 10~3
1.5 x 10~3
2.3 x 1(T4
3.6 x 10~4
1.5 x 1(T3
4.5 x 10~5
1.2 x HT1
1.2 x KT1
6.9 x ID"2
4.5 x 1(T4
3.2 x 10~3
5.9 x 1(T3
3.2 x 1(T3
3.2 x 10~3
3.2 x 1CT3
4.9 x 10~2
6.8 x 10~2
6.8 x 1(T2
4.9 x 10~2
6.8 x 1(T2
4.9 x HT2
1.4 x 1(T5
1.2 x 10~3
1.4 x 10~5
1.4 x 1CT5
Median
2.2 x 1(T5
5.3 x 10~6
5.3 x 1(T6
<8.9x ID"5
<8.9x 1(T5
<8.7x 10~5
<8.7xlO~5
<8.7x 10~5
<8.7x 10~5
2.2 x 1(TS
2.2 x 10~5
1.4 x 1(T3
1.4 x 10~3
1.4 x 1(T3
1.4 x 1(T3
7.3 x 10~3
1.6 x 1(T3
1.2 x 10~3
2.3 x 1(T4
3.6 x 1(T4
1.4 x 10~3
2.2 x 1(TS
5.6 x 10~2
5.6 x 1(T2
5.1 x 1(T2
4.8 x 10"4
2.5 x 1(T3
5.1 x 10~3
2.5 x ID"3
2.5 x 1(T3
2.5 x 10~3
4.8 x ICT2
5.3 x 10~2
5.3 x 1(T2
4.8 x 1(T2
5.3 x 10~2
4.8 x 1(T2
8.6 x 10~6
6.5 x 1(T4
8.6 x 1(T6
8.6 x ID"6
SD
4.5 x 1(TS
0.0 x 10°
0.0 x 10°
<6.2x MT5
7.6 x 10~4
2.6 x 10~3
3.1 x 10~3
7.7 x 10~4
0.0 x 10°0.0 x 10°
1.3 x ID"1
6.2 x HP2
3.1 x 1Q-4
3.6 x 10~3
2.9 x 10~3
2.8 x HP2
3.8 x 10~2
1.5 x ID"5
1.5 x 10~3
Minimum
9.7 x 10~6
5.3 x 10~6
<8.9xlO-5
<4.3x 10~5
8.2 x ID"4
3.2 x HT3
7.0 x 10~4
9.1 x 10-4
2.3 x ID"4
3.6 x 10~4
8.6 x 10~3
6.0 x 10~3
7.1 x 10~5
6.3 x 10~4
3.7 x ID"4
9.4 x ID"3
2.6 x 10~2
3.4 x 1Q-6
2.1 x 10~5
Maximum
1.3 x ID"4
5.3 x 10~6
<8.9x ID"5
<1.3x 10"4
2.3 x ID"3
8.1 x 10~3
6.4 x 10~3
2.4 x 10~3
2.3 x 10~4
3.6 x ID"4
3.6 x 10"1
2.0 x 10-1
8.8 x 10~4
2.9 x 10~2
1.6 x 10~2
8.1 x 10~2
1.7 x 10"1
5.9 x 10~s
5.5 x 10~3
a Decay corrected to 1999.SD: standard deviation.
21
TABLE IX. ACTIVITY11 OF 239+240pu PER UNIT WET WEIQHT OF LOCAL(BIKINIAN) FOOD (Bq/g) [20]
Local food
Reef fishTuna (pelagic fish)Mahi mahiMarine crabs (shellfish)LobsterClamsTrochusTridacna muscleJedrulOctopusTurtleChicken muscleChicken liverChicken gizzardPork musclePork kidneyPork liverPork heartBird muscleBirds' eggsChicken eggsTurtle eggsPandanus fruitPandanus nutsBreadfruitCoconut juiceCoconut milkTuba/jekeroDrinking coconut meatCopra meatSprouting coconutMarshallese cakePapayaSquashPumpkinBananaArrowrootCitrusRain waterWell waterMaloloCoffee/tea
Mean
1.3 x 1(T5
1.9 x 10~6
1.9 x 1(T6
3.6 x 1(T5
3.6 x 1(T5
8.3 x 1(T4
8.3 x 1(T4
8.3 x 1(T4
8.3 x 1(T4
1.3 x W~B
1.3 x 10~5
7.7 x 1(T6
7.7 x 1(T6
7.7 x 1<T6
7.7 x 1(T6
3.5 x 10~5
1.2 x 1(T4
5.9 x 10-6
1.3 x 10"6
1.3 x HP5
7.7 x 10~6
1.3 x 1(T5
3.2 x 1(T6
3.2 x 10~6
1.8 x 1(T6
1.0 x 10~6
1.9 x 1(T6
1.9 x 1(T6
2.7 x 10~6
1.9 x 1(T6
1.9 x l(Te
1.9 x 1(T6
2.5 x 10~6
2.2 x 10~5
2.2 x 10~5
2.5 x 10~6
2.2 x 10~5
2.5 x 1(T6
3.3 x 10~7
6.1 x 1CTT
3.3 x 10~7
3.3 x 1(T7
Median
8.6 x 1<T6
2.1 x 10~6
2.1 x 10~6
3.6 x 1(TS
3.6 x 10~5
8.1 x 1(T4
8.1 x 10~4
8.1 x 1(T4
8.1 x 10~4
8.6 x 1(T6
8.6 x 1(T6
6.6 x 10~6
6.6 x 1(T6
6.6 x 10~6
6.6 x 1(T6
2.8 x 1(T5
1.2 x 10~4
3.6 x HT6
8.6 x 10"6
8.6 x ICr6
6.6 x 10~6
8.6 x 10~6
1.8 x 1(T6
1.8 x 10~6
9.6 x NT7
6.0 x 10~7
7.7 x 1Q-7
7.7 x 10~7
1.5 x 10~6
7.7 x 10~7
7.7 x 1(T7
7.7 x 10~7
1.0 x 10~7
5.0 x 10~6
5.0 x 10~6
1.0 x 10~7
5.0 x 10~6
1.0 x 10~7
1.6 x 10~7
3.9 x 10~7
1.6 x 10~7
1.6 x 10"7
SD
1.2 x 10~5
1.3 x 10~6
0.0 x 10°
6.9 x 10~4
5.6 x ID"6
3.3 x 10~s
8.2 x KT5
4.1 x 10~6
3.1 x 10~6
2.8 x 10~6
1.0 x 10~6
3.5 x 10~6
2.7 x 10~6
4.2 x 10~6
3.8 x 10~5
4.8 x 10~7
6.2 x 10~7
Minimum
1.1 x 10~6
5.6 x 10~7
3.6 x ID"5
8.2 x 10~6
2.7 x 10~6
6.4 x 10~6
3.6 x 10~5
3.4 x 10~6
3.4 x 10~7
1.4 x 10~7
3.3 x 10~7
1.7 x 10~7
1.4 x ID"7
6.2 x 10~8
5.0 x 10-7
7.0 x 10"8
1.1 x 10~7
Maximum
4.1 X 10~5
4.0 X 10"6
3.6 x 10~5
1.9 x 10~3
1.4 x 1Q-6
7.0 x ID"5
2.0 x 10-"1.1 x 10~5
1.1 x 10~5
9.8 x 10~6
2.2 x 10~6
1.4 x HT5
1.0 x 10~5
7.3 x 10~6
1.3 x 10~4
1.9 x 10"6
3.3 x ID"6
a Decay corrected to 1999.SD: standard deviation.
22
TABLE X. ACTIVITY*1 OF 241Am PER UNIT WET WEIGHT OF LOCAL (BIKINIAN)FOOD (Bq/g) [20]
Local food
Reef fishTuna (pelagic fish)Mahi mahiClamsTrochusTridacna muscleJedrulOctopusTurtleChicken muscleChicken liverChicken gizzardPork musclePork kidneyPork liverPork heartBird muscleBirds' eggsChicken eggsTurtle eggsPandanus fruitPandanus nutsBreadfruitCoconut juiceCoconut milkTuba/jekeroDrinking coconut meatSprouting coconutMarshallese cakeCopra meatPapayaSquashPumpkinBananaArrowrootCitrusRain waterMaloloCoffee/tea
Mean
6.5 x 1(T6
1.3 x 1(T6
1.3 x 1(T6
4.6 x 1(T4
4.6 x 1(T4
4.6 x 1(T4
4.6 x 1(T4
6.5 x 1(T6
6.5 x 1(T6
6.0 x 1(T6
6.0 x 10~6
6.0 x 10~6
6.0 x 10~6
1.2 x 10~s
5.2 x 10~s
1.8 x 10~s
6.5 x 10~6
6.5 x 10~6
6.0 x 10~6
6.5 x 10~6
3.8 x 10~6
3.8 x 10~6
1.2 x 10~6
8.5 x nr6
1.1 x MT6
1.1 x 10~6
3.6 x 10~6
1.1 x 10~6
1.1 x 10~6
1.1 x 10~6
3.6 x 10~7
3.0 x 10~6
3.0 x 10~6
3.6 x 10~7
3.0 x 10~6
3.6 x 10~7
3.7 x 10~8
3.7 x ID"8
3.7 x 10~8
Median
3.1 x KT6
1.3 x 10~6
1.3 x HP6
3.7 x 10~4
3.7 x 10~4
3.7 x 10~4
3.7 x ID"4
3.1 x 10~6
3.1 x 10~6
7.6 x ID"6
7.6 x 10~e
7.6 x 10~6
7.6 x 10-6
5.1 x 10~6
4.4 x 10~5
1.8 x 10~5
3.1 x 10~6
3.1 x 10~6
7.6 x 10~6
3.1 x 10~6
2.7 x HT6
2.7 x 10~6
2.9 x HP7
8.5 x 10~6
6.8 x 10-7
6.8 x 10~7
1.9 x 10~6
6.8 x 10~7
6.8 x 10-7
6.8 x ID"7
3.6 x ID"7
3.0 x KT6
3.0 x ID"6
3.6 x KT7
3.0 x 10~6
3.6 x HT7
3.7 x 10~8
3.7 x ID"8
3.7 x 10~8
SD
1.0 x 10~5
0.0 x 10°
4.2 x 10~4
4.4 x ID"6
1.4 x 10~5
2.5 x 10~s
0.0 x 10°
4.8 x 10~6
1.9 x 10~6
0.0 x 10°
5.1 x 10~6
1.1 x 10~6
2.8 x 10~7
0.0 x 10°
5.4 x 10~9
Minimum
4.1 x ID"8
1.3 X 10~6
1.8 x KT5
9.5 x KT7
3.1 x 10~6
3.2 x 10~5
1.8 x 10"5
2.8 x 10~7
1.5 x 10~7
8.5 x 10~6
5.0 x HT7
2.3 x 1Q-7
1.6 x 1Q-7
3.0 x 10~6
3.3 x 10~8
Maximum
4.0 x KT5
1.3 x 10~6
1.2 x 1Q-3
9.4 x 10~6
2.8 x 10~5
8.1 x 10~5
1.8 x 10~5
1.5 x 10~5
5.3 x 10"6
8.5 x 10~6
1.6 x 10~5
3.9 x 10~6
5.6 x 10~7
3.0 x 10~6
4.1 x ID"8
a Decay corrected to 1999.SD: standard deviation.
23
TABLE XI. ISOLINES (IN FIG. 3)OF ABSORBED DOSE RATE IN AIR ATBIKINI ISLAND (AUGUST 1978)
Annual absorbed dose in airContour area at 1 m above surface
(mGy)
ABCDEFGHIJKLM
<0.0110.011-0.0310.031-0.0660.066-0.1230.123-0.2020.202-0.3510.351-0.5260.526-0.7890.789-1.231.23-1.751.75-2.632.63-3.513.51-5.26
Caesium-137 is found in very low concentra-tions in lagoon sediment, lagoon water and fish. Com-pounds of caesium are generally highly soluble andthe majority of the original inventory of 137Cs in thelagoon has long since dissolved and become mixedwith the world's oceans.
Strontium-90, which is chemically similar tocalcium, a major component of the coral soils (asCaCOs), competes with the very large quantities ofcalcium available for uptake by and distribution inmarine species. It is also chemically bound in thegrowing coral and in the coral sediment, and remainsin the lagoon environment, primarily in the carbonatematrix. Consequently, 90Sr is relatively unavailable tomarine life [38, 39).
The occurrence and redistribution of thetransuranic radionuclides 239+240pu an(j 241 m m coral sediments and the mobilization and redistri-bution in the water column, both in solution andin association with resuspended particulate mate-rial, are discussed in the literature [40-48]. Publishedestimates of transuranic inventories are provided inRefs [43, 44, 47]. Distributions in surface sedimentat Bikini Atoll were constructed and inventories wereestimated from published and unpublished data. It
should be noted that sediment inventories for BikiniAtoll were estimated from substantially fewer datathan were available for Enewetak Atoll.
The initially estimated 239+240pu inventorybased on the analysis of sediment columns of 16 cmdepth taken from Bikini Atoll was 55.5 TBq. How-ever, in a few deeper cores, which are difficult toobtain from carbonate deposits, 239+240pu an(j
2/*i Am
were detected at depths below 20 cm. The inven-tories computed to a depth of 16 cm can there-fore be assumed only to represent lower limits. Fromrecent results [48], the best estimate for the totalinventory of 239+240pu m Bikini Atoll sediments is103 ± 25 TBq. The best estimate of the total inven-tory for 241Am is 93 ± 10 TBq.
6.5. RATES OF ABSORBED DOSE IN AIR
Measurements of absorbed dose rates in air dueto gamma radiation were made at Bikini Atoll both aspart of the NWRS [1] and as part of the LLNL survey[9, 16]. The measurements were made using high res-olution solid state detectors 1 m above ground levelto obtain an average of the radiation emissions overa circle about 10 m in radius. Earlier measurementshad also been obtained by means of an aerial mea-surement technique [15].
Comparisons between the two approaches weremade by locating the ground measurement points onthe aerial photographs of the islands of the atoll ontowhich isodose contours were superimposed [1]. Somedifferences were found in the results, as expected,owing to the uneven patterns of ground activity, espe-cially for the smallest islands of the atoll, and differ-ences in resolution for the different methods. (Theresolution was about 20 m for the in situ approachand about 100 m for the aerial approach.) However,the ratio between the mean value of the in situ mea-surements and the corresponding value of the aerialmeasurements is close to 1, showing good agreementbetween them.
On Bikini Island the annual absorbed dose inair measured at 1 m above the ground varied fromabout 0.01 to 5 mGy (see Fig. 3 and Table XI). Thesemeasurements were conducted in August 1978; thevalues, decay corrected to 1999, would be about 60%of those in 1978: from 0.006 to 3 mGy.
24
"53I
ISi
I
a<a
sfi
25
7. ESTIMATES OF POTENTIAL RADIATION DOSESTO PEOPLE RESETTLING BIKINI ISLAND UNDER
PRESENT CONDITIONS
7.1. SOURCES AND PATHWAYSOF EXPOSURE
The radiation exposure of persons living atBikini Island would result from two sources: (1) natu-ral sources of radiation; and (2) residues from nuclearweapon testing.
For natural sources of radiation, the main expo-sure pathways are external exposure to cosmic radia-tion and external and internal exposure to terrestrialradionuclides which — in the case of the MarshallIslands — is dominated by the intake of naturallyoccurring radionuclides in foodstuffs, mainly fish.
For residual activity, the main exposure path-ways of relevance are external exposure due toradioactive materials on the ground and internalexposure arising from the ingestion of radioactivematerials in foodstuffs produced on the island. Theingestion pathway includes the intake of terrestrialand marine foods, possibly small quantities of soil,stored rain water and groundwater. Inhalation ofresuspended radioactive materials is also a plausiblepathway of exposure.
There is evidence in some parts of the worldof a condition called 'pica1 in which people, mainlychildren, may deliberately ingest non-food items suchas soil in substantial quantities. In the case of theMarshall Islands, such intakes could result in non-trivial radiation doses due mainly to actinides such asplutonium and americium. However, such intakes areconsidered to be unlikely and, even if they did occur,evidence suggests that pica cases are intermittent andwould not extend for periods of a year at a sustainedrate of intake. Furthermore, it has been pointed outthat there was no indication from a urine analysisstudy undertaken on the populations of Rongelap,Enewetak and Bikini Atolls [49] and a bone autopsystudy on the inhabitants of Rongelap Atoll [50] of asignificant route of intake for actinide elements.
Other potential routes by which exposure couldoccur, such as exposure while swimming or diving inthe lagoon, have been analysed, with account taken of
the known radionuclide concentrations in water andsediments. The contribution to dose via these path-ways was found to be so small that they could beneglected in the general dose assessment.
As the reviewed assessments focused on dosesto adults, an independent analysis was carried out ofthe potential significance of doses to children [51].This study concluded that, on the basis of theinformation available, the estimated doses foradults serve as conservative estimates of doses forchildren.
7.2. DOSES DUE TO NATURAL SOURCES
The worldwide exposure to natural back-ground radiation has been estimated by UNSCEAR.The average annual effective dose is 2.4 mSv [52],apportioned as shown in Table XII, which also pro-vides the estimated average dose in the MarshallIslands [53]. In the case of the northern atolls of theislands, the annual external effective dose due to cos-mic radiation is significantly lower than the globalaverage: 0.22 mSv. The annual external effective dosedue to naturally occurring terrestrial radionuclides onthe atolls is insignificant, but the annual committedeffective dose from the intake of naturally occurringradionuclides such as 210Po and 210Pb in food is about2.2 mSv/a. The source of 210Po and 210Pb in the dietis fish, which constitutes a major component of thediet of the atoll dwellers. In total, therefore, the natu-ral background doses at Bikini Atoll can be assumedto be comparable with the global average [54].
7.3. DOSES DUE TO RESIDUES FROMNUCLEAR WEAPON TESTING
Two independent assessments were reviewed(the NWRS [1] and the LLNL [20] study). Thesehad been performed in order to evaluate the potentialcommitted doses to the population who in the futuremight live on Bikini Island.
26
TABLE XII. AVERAGE ANNUAL EFFECTIVE DOSES DUE TO NATURALSOURCES OF RADIATION (mSv)
SourceGlobal average annual effective dose
in areas ofnormal background radiation
Average annual effective dosein the Marshall Islands
Th
Cosmic rays
Cosmogenic radionuclides
Terrestrial radionuclides:40K
238U series:238rj _>234Tj _>230226Ra222Rn -+214Po2iopb ^2iopo
Total 238U series232Th series
Total (rounded)
0.38
0.01
0.3
0.0140.0041.20.05
1.4
0.27
2.4
0.22
0.01
0.18
NilNilNil
210Po diet 1.8210Pb diet 0.20
Nil
2.4
For external irradiation, the average effectivedose contribution due to external gamma radiationwas estimated by means of direct measurementsinside and outside houses, measurements in the vil-lage area and aerial survey measurements. The doseestimate is based on the following occupancy assump-tions, made on the basis of discussions with the Mar-shallese people and observations: ten hours per dayspent inside the houses, nine hours per day outsidein the village area, three hours per day in the interiorregion of the island and two hours per day on thebeach or lagoon. The average annual effective dosebased on this occupancy model, and decay correctedto 1999, is 0.4 mSv.
For internal doses, both assessments used con-version factors from activity intake into effective dosewhich are compatible with those established in theBasic Safety Standards [25].
The NWRS [1] presumed a low but still rea-sonable caloric value in the diet model. The dietincluded a 25% contribution from rice, which all Mar-shallese have as a common dietary component. Thedose assessment was a probabilistic (Monte Carlo)calculation and used probability distributions for allparameters. The model was not described in theNWRS report because the report was not intendedto include technical details, but there is a description
of the probabilistic dose calculation in Ref. [55]. Themedian doses are presented in the NWRS report withestimated uncertainties as a robust description of thebest estimate of dose for skewed probability distribu-tions. The study predicted an annual individual doseof 8.0 mSv (if the dose due to natural backgroundradiation were added, this would result in an annualeffective dose of about 10.4 mSv).
The second study, by LLNL [20], assumed ahigh calorie diet model, as listed in Table XIII.The information on diets was obtained from a lim-ited study carried out in the Marshall Islands. TheUS National Academy of Sciences reviewed the dietassumptions [56]. The overall dose, i.e. the sum ofthe annual effective dose due to external radiationand the committed effective dose due to intakes inthe year being considered, on the assumption of adiet consisting of both imported and locally derivedfoods, is 4.0 mSv (if the dose due to natural back-ground radiation were added, this would result in anannual effective dose of 6.4 mSv). For a diet consistingof only locally derived foodstuffs, the annual overalldose is 15 mSv (if the dose due to natural backgroundradiation were added, this would result in an annualeffective dose of about 17.4 mSv).
If the NWRS estimate was adjusted to accountfor the LLNL's assumption of a high calorie intake,
27
TABLE XIII. SOME DIET MODELS FOR ADULTS LIVING ON BIKINI ISLAND [1, 20]
Local component ofan 'imported foods' diet
Local food
Reef fishTunaMahi mahiMarine crabsLobsterClamsTrochusTridacna muscleJedrulCoconut crabsOctopusTurtleChicken muscleChicken liverChicken gizzardPork musclePork liverPork heartBird muscleBirds' eggsChicken eggsTurtle eggsPandanus fruitPandanus nutsBreadfruitCoconut juiceCoconut milkDrinking coconut meatCopra meatSprouting coconutMarshallese cakePapayaPumpkinBananaArrowrootCitrusPiain waterWell waterMaloloCoffee/tea
Total
g/d
24.213.93.561.683.884.560.101.673.083.134.514.348.364.501.665.672.600.312.711.547.259.368.660.50
27.299.151.931.712.27.79
11.76.591.240.0203.930.10
313207199228
1322
kcal/d
33.819.43.921.513.493.650.0802.142.462.194.513.86
14.27.382.46
25.56.270.604.612.31
11.814.05.201.33
35.310.917932.350.36.23
39.22.570.370.018
13.60.0490.000.000.000.00
547
'Local foods only' diet
g/d
86.872.021.419.535.258.10.24
11.419.424.949.017.831.217.73.32
13.96.700.62
26.422.841.2
23563.02.00
18633312218171.3
1220.00
27.05.440.58
94.90.20
629430
0.000.00
3083
kcal/d
12110123.517.631.746.50.19
14.617.417.549.015.853.029.04.91
62.616.11.21
44.834.167.2
35237.85.32
24236.6
42118
29597.80.00
10.51.630.51
3280.100.000.000.000.00
2783
28
-.15
§0)10tag
II 5
] Residual activity
4.02.4
8.0
Natural Local +background imported food,
high calorieintake
15.0
Local food Local foodonly, low only, high
calorie intake calone intake
The contributions to annual effective dose byradionuclide and by pathway (local diet assumptions)are presented in Table XIV and Fig. 5 [8]. It can beseen that uptake of 137Cs into terrestrial foodstuffsaccounts for the largest fraction of the total estimated
FIG. 4- Comparison of natural background and predictedaverage annual effective doses for residents of BikiniIsland for different types of diet. TABLE XIV. PREDICTED ANNUAL EFFEC-
TIVE DOSES BY PATHWAY AND RADIO-NUCLIDE FOR A LOCAL DIET [8]
£.
T3P
16
14
12
8
6
4
2
0
r 14.75-
-
.
-
-
0.4 0.001
15
External Ingestion InhalationExposure pathway
Total
FIG. 5. Contribution by pathway to the predicted annualeffective dose for a local high calorie intake diet [8].
Exposure pathway
External gamma
Ingestion137Cs90Sr239+240pu
241 Am
Inhalation239+240pu
241 Am
Total (rounded)
Annual dose(mSv)
0.40
14.60.150.00190.0010
0.000740.00049
15
the adjusted annual effective dose would becomeabout 14 mSv. The two assessments are thereforecomparable in their results.
The review of the information presented inthe two dose assessments showed that the assumeddietary models are appropriate, and that theapproaches used are satisfactory. The similar resultsobtained in the two independent assessments providea good degree of assurance of the reliability of theestimated doses.
For the purposes of this review, it was consid-ered prudent to take the upper estimates of annualdose, based on a 'local food only, high calorie intakediet', and thus the annual effective dose under currentconditions for persons living on an entirely locallyderived diet is taken to be about 15 mSv. Fig-ure 4 presents the results of the various assessmentsgraphically.
TABLE XV. THIRTY YEAR PREDICTED COM-MITTED EFFECTIVE DOSES BY PATHWAYAND RADIONUCLIDE FOR A LOCAL DIET [20]
Exposure pathway Integral dose(mSvj
External gammaIngestion
137Cs90Sr239+240pu
241 Am
Inhalation239+240pu
241 Am
Total (rounded)
9.1
3305.90.0980.062
0.0690.050
345
29
dose and that the external gamma exposure path-way accounts for most of the remainder. The con-tribution of 90Sr to the total dose is minor andthe contributions from 239+240pu an(j 24i^m ^ginsignificant.8 Marine foods, stored rain water andgroundwater, and inhalation of resuspended soil aspathways together account for less than 1% of thedose.
Since the dominant contribution to dose comesfrom 137Cs, the annual doses from living on BikiniAtoll will decline approximately according to theradioactive decay of this radionuclide. In the periodfrom now to 30 years in the future, the total dosereceived — on the assumption of a locally derived dietand with natural background contributions added —is estimated to be about 350 mSv [20] (Table XV andFig. 6).
The inventory of transuranic radionuclides inthe lagoon is an important potential source of radia-tion exposure and is associated with the many com-ponents (forams, Halimeda (cactus algae) remains,unidentifiable fine and coarse carbonate materials,corals, shells, etc.) making up the lagoon sediments.The source term for the radionuclides in solutionand in the organisms is the inventory associatedwith the different components that make up the sed-imentary reservoir. Radionuclides are found accu-mulated by zooplankton and there are also manyreports of radionuclides accumulated by fish species,benthic invertebrates and algae in the Bikini Atolllagoon. Therefore, there is evidence that plutonium isindeed transferred into the aquatic ecosystem in smallbut measurable concentrations through the action of(perhaps many) biogeochemical processes acting on
350<D
•| 300
1-5-250
it200
piooT3£ 50
QL0
r 336
-
-
-
-
-9.1 0.1
345
External Ingestion Inhalation
Exposure pathway
Total
FIG. 6. Contribution by pathway to the predicted 30 yeareffective dose for a local high calorie intake diet fSOj.
contaminated components of the sedimentary reser-voir at the atoll.
However, it is noted that the observed transferof these radionuclides through the marine food chainto human foodstuffs is very low, such that any asso-ciated radiological impact would be expected to benegligible. It is nevertheless necessary also to reviewother mechanisms or pathways by which there couldbe a significant transfer of radionuclides to people liv-ing on the atoll. In this context, the available infor-mation indicates that the actions of severe stormsand hurricanes in the area over the past 40 yearsdo not appear to have mobilized or transported thetransuranic radionuclides to any significant extent [8].
It is concluded that on the evidence presentedit seems unlikely that the plutonium in the lagoonsediment could constitute a significant source of radi-ation doses to a population resettling Bikini Island.
8The minor contribution of the transuranic radionuclidespredicted from the environmental data and models has beencorroborated in the study of 239+i40pu in autopsy bone sam-ples from people who had lived on Rongelap Atoll for theirentire lives [50.]
30
8. RADIATION PROTECTION CRITERIA
8.1. PROTECTION AGAINST RADIATION
As indicated in Section 5, exposure to radia-tion may have detrimental effects on the health ofpeople, and it is for this reason that standards ofsafety for protection against radiation are established.It should be emphasized that radiation and radioac-tive substances are a natural, permanent and inherentfeature of the human environment, both in the Mar-shall Islands and elsewhere: people are unavoidablyand permanently exposed to radiation from naturalsources, such as that from the cosmos and naturallyoccurring radioactive materials in the geosphere. Inaddition, they are subject to exposure to many arti-ficial sources of radiation nowadays used widely forhuman welfare. The background exposure caused bythese natural and artificial sources is incurred to dif-ferent extents by everyone and, therefore, radiationexposure can only be controlled and restricted, andnot eliminated entirely, by radiation safety standards.
International radiation safety standards, suchas the Basic Safety Standards, are intended to pro-vide guidance on safety for national regulation ofthe peaceful, beneficial uses of radiation and nuclearenergy. The practice of nuclear weapon testing wastherefore not considered in the establishment of theBasic Safety Standards. This section is intended todescribe the protection policy and main requirementsof these Standards with the aim of deriving ad hocguidance for dealing with the particular case of theradiological conditions caused by nuclear weapontesting at Bikini Atoll.
8.2. INTERNATIONAL RADIATIONSAFETY STANDARDS
The Basic Safety Standards are the worldwideagreed radiation safety standards set out by the spe-cialized sponsoring international organizations. Theyrely on the scientific information on radiation levelsand health effects compiled globally by UNSCEAR,a body set up by the United Nations General Assem-bly in 1955; the latest report of UNSCEAR to theGeneral Assembly was issued in 1993 [30]. The safetycriteria in the Basic Safety Standards are based pri-marily on the recommendations of the ICRP, a non-
governmental scientific organization founded in 1928to establish basic principles and recommendations forradiation protection. The most recent recommenda-tions of the ICRP were issued in 1991 [57].
8.3. ACTIVITIES INVOLVINGRADIATION EXPOSURE
The Basic Safety Standards apply to twoclasses of activity involving radiation exposure. Theseactivities are termed practices and interventions.Practices are those activities which make deliberateuse of radiation sources for a beneficial purpose —such as the use of X rays in medical diagnosis —where their use may lead to adventitious radiationdoses which add to the doses that people normallyincur due to background radiation. Interventions areactivities to reduce the doses caused by existing defacto situations — such as situations involving expo-sure to elevated background radiation levels due tonatural sources or exposure to residues from pastevents and activities — where the doses incurredare sufficiently high and it is feasible and reasonableto take remedial measures to reduce them to someextent.
8.4. PRACTICES
For practices, the Basic Safety Standardsrequire, among other things, that:
"No practice or source within a practice shouldbe authorized unless the practice produces sufficientbenefit to the exposed individuals or to society to off-set the radiation harm that it might cause... The nor-mal exposure of individuals shall be restricted so thatneither the total effective dose nor the total equiva-lent dose to relevant organs or tissues, caused by thepossible combination of exposures from authorizedpractices, exceeds any relevant dose limit... In rela-tion to exposures from any particular source withina practice...protection and safety shall be optimizedin order that the magnitude of individual doses, thenumber of people exposed and the likelihood of incur-ring exposures all be kept as low as reasonably achiev-able, economic and social factors being taken into
31
account, within the restriction that the doses to indi-viduals delivered by the source be subject to doseconstraints."
These radiation protection requirements forpractices are referred to as justification of practices,optimization of protection and limitations of individ-ual doses.
In summary, therefore, the Basic Safety Stan-dards require that additional doses above backgroundlevels expected to be delivered by the introduction orproposed continuation of a practice be restricted. Therestriction is intended to be applied prospectively tocontrol and constrain the extra doses forecast andseeks to ensure that:
— The practice is justified, taking into account thedoses it will deliver to people;
— The protection against the radiation exposurecaused by the sources involved in the practice hasbeen optimized in order to keep all doses as lowas reasonably achievable under the prevailing cir-cumstances;
— The additional doses (above the backgrounddose) expected to be incurred by any individ-ual do not exceed prescribed dose limits (the cur-rently established limit of additional doses abovebackground doses — excluding medical exposures— for members of the public being 1 mSv ina year under normal circumstances and up to5 mSv in a year in special circumstances).
8.5. INTERVENTIONS
For interventions, the Basic Safety Standardsstate that:
"Intervention is justified only if it is expectedto achieve more good than harm, with due regard tohealth, social and economic factors. If the dose levelsapproach or are expected to approach [specified] lev-els, protective actions or remedial actions will be jus-tified under almost any circumstances... Optimizedintervention levels and action levels shall be specifiedin plans for intervention situations, on the basis ofthe guidelines given [in the Basic Safety Standards],modified to take account of local and national condi-tions, such as: (a) the individual and collective expo-sures to be averted by the intervention; and (b) theradiological and non-radiological health risks and thefinancial and social costs and benefits associated withintervention."
The radiation protection requirements forinterventions are referred to as justification of inter-ventions, and optimization of the protective measures.
In summary, therefore, the Basic Safety Stan-dards require that:
— Existing radiation exposure situations shall beassessed in order to determine whether an inter-vention is justified to reduce the doses being deliv-ered because of the situation;
— Should the intervention be justified and there-fore undertaken, the form, nature and scale ofthe protective measures should be optimized inorder to ensure that they are not disproportion-ate to the benefit gained from the reduction inradiation doses.
Importantly, as dose limits are applicable to theincreases to the background radiation dose expectedto arise from a practice, they are not applicable tointerventions, which by definition are intended toreduce (rather than increase) doses.
8.6. THE SITUATION AT BIKINI ATOLL
The situation at Bikini Atoll does not fit theconcept of a practice. The practices identified forthe application of the Basic Safety Standards includethe use of radiation or radioactive substances formedical, industrial, veterinary, agricultural and edu-cational purposes, as well as for the generation ofnuclear electricity. The practice of nuclear weapontesting is not contemplated in these internationalstandards intended to regulate the peaceful, bene-ficial uses of radiation and nuclear energy. In anycase, in the Marshall Islands the practice of nuclearweapon testing was terminated long ago. The addi-tional doses caused by such a practice can no longerbe controlled prospectively and what remains is anexposure situation only amenable to intervention, i.e.to the introduction of remedial protective measuresaimed at reducing the radiation doses caused by theexisting situation.
8.7. INTERVENTION SITUATIONS
Two types of intervention situations are rec-ognized in the Basic Safety Standards. The firstrelates to emergency exposure situations, such as inthe immediate aftermath of a radiological accident,requiring protective actions to reduce or avert the
32
temporary (short term) doses caused by the situa-tion. The second relates to chronic exposure situa-tions where long term environmental radiation levelsexist leading to continuing exposure of a resident pop-ulation, usually at a relatively low dose rate, requiringremedial actions to reduce the exposure rate.
The intervention situation in Bikini Atoll,where a returning population would commencereceiving continued radiation exposures, for instancefrom locally grown foods, represents an unusualexample of intervention in chronic exposure situa-tions. In this case, an a priori intervention took placewhen the Bikinians were first evacuated from BikiniIsland and then a new intervention was undertakenwhen those who had returned to their island in 1970were re-evacuated in 1978. The current interventionissues are whether that specific protective measure— evacuation — can be terminated and whether anyother protective measure should be instituted to per-mit the safe resettlement of Bikini Island.
8.8. GENERIC INTERVENTION LEVEL
The underlying policy on intervention set inthe Basic Safety Standards is that the decision onwhether or not intervention should be contemplatedand how much the existing dose levels should bereduced depends on the circumstances of each indi-vidual case. In order to determine whether and whenan intervention should be undertaken, interventionlevels are established. Intervention levels should bedetermined in terms of the doses expected to beaverted by a specific remedial action intended to pro-tect people from exposure. The intervention levelsare usually expressed in quantities derived from theavertable dose. In the case of chronic exposure sit-uations these derived levels are usually referred toas action levels. They are always expressed in termsof dose rate or activity concentration above whichremedial actions to reduce exposure levels should becarried out. Remedial action — or remediation — istherefore the term used in this report to refer to aprotective action taken when a specified action levelis exceeded in a chronic exposure situation in orderto reduce radiation doses that might otherwise bereceived.
Intervention action levels, therefore, areexpected to be determined on an ad hoc basis, i.e.case by case, and tailored to the specific circum-stance of the intervention situation. However, therehas been a recognized need for simple and interna-
tionally agreed guidance on generic levels applicableto any intervention situation, particularly in chronicexposure situations.
The Basic Safety Standards establish somegeneric levels for interventions as follows:
(a) For the justification of the intervention:
— Dose levels at which intervention isexpected to be undertaken under any cir-cumstances.
(b) For the optimization of protective measures inemergency exposure situations:
— Optimized avertable dose levels for shel-tering, evacuation and iodine prophy-laxis.
— Optimized dose levels for initiating andterminating temporary relocation and forpermanent resettlement.
(c) For the optimization of action levels in thequasi-chronic exposure situation caused by thepresence of radioactive materials in foodstuffs:
— Generic action levels of activity per unitmass of foodstuff.
(d) For the optimization of action levels in theparticular case of chronic exposure to radon:
— Optimized action level for activity con-centration of radon in the air fordwellings.
— Optimized action level for activity con-centration of radon in the air for work-places.
Although there is no explicit international guid-ance for generic action levels for chronic exposuredue to radioactive residues from previous activitiesand events, in particular from events such as nuclearweapon testing, ad hoc generic guidance can bederived implicitly from the guidance established inthe Basic Safety Standards for other situations. More-over, the typical levels of doses caused by chronicexposure to the unavoidable natural background radi-ation could also be used as a reference for purposesof comparison.
8.8.1. Guidelines for justifying interventions
The Basic Safety Standards establish that ifdoses approach levels at which the likelihood of dele-terious health effects is very high, intervention would
33
TABLE XVI. LEVELS OF EQUIVALENTDOSE RATE AT WHICH INTERVENTIONIS EXPECTED TO BE UNDERTAKEN UNDERANY CIRCUMSTANCES
Organ or tissueEquivalent dose rate
(mSv/a)
GonadsLens of the eyeBone marrow
200100400
TABLE XVII. GENERIC LEVELS FORTEMPORARY RELOCATION ANDPERMANENT RESETTLEMENT
Intervention Initiate Terminate
Temporary-relocation
Permanentresettlement
30 mSv/month 10 mSv/month
Lifetime dose > 1 Sv
be expected to be undertaken under almost any cir-cumstances. These quasi-mandatory levels, which areestablished in the Basic Safety Standards, depend onthe organ exposed, and for chronic exposure situa-tions vary from a level of equivalent dose of 100 mSvper year for the lens of the eye to 400 mSv per yearfor the bone marrow (see Table XVI).
From the established levels of equivalent dosesand on the basis of recommended weighting factorsto take account of the radiosensitivity of the relevantorgans, it could be construed that intervention wouldnot be 'expected to be undertaken under any circum-stances' unless the annual effective dose exceeds sev-eral tens of millisieverts. At lower doses, proposedinterventions need to be justified on a case by casebasis. The following subsections develop some genericguidance for such cases.
8.8.2. Guidelines for emergency exposuresituations that may be applicableto chronic exposure situations
8.8.2.1. Intervention levels for relocationand resettlement
Temporary relocation and permanent resettle-ment are among the more extreme protective mea-sures available to control exposures to the public in
the event of a radiological emergency. Table XVIIshows the generic levels established in the BasicSafety Standards for temporary relocation and per-manent resettlement.
Temporary relocation is used to mean the orga-nized and deliberate removal of people from thearea affected during an extended but limited periodof time (typically several months) to avert expo-sures, principally from radioactive material depositedon the ground and from inhalation of any resus-pended radioactive particulate material. During thisperiod, people would typically be housed in tempo-rary accommodation. As the radiological situationis temporary, the generic guidelines to initiate andterminate relocation refer to relatively high levels ofdose: 30 mSv and 10 mSv per month, respectively.
Permanent resettlement is the term used forthe deliberate removal of people from the area withno expectation of return. Permanent resettlementshould, according to the Basic Safety Standards, beconsidered if the lifetime dose over 70 years can-not be reduced by other means and is projected toexceed 1 Sv. This lifetime dose corresponds to anaverage annual dose of about 14 mSv. When doses arebelow this level, permanent resettlement is unlikely tobe necessary. It can thus be construed that if dosesfall below an average annual effective dose of about10 mSv, it would not indicate a requirement for per-manent resettlement, but rather for the terminationof relocation if it has been instituted.
8.8.3. Guidelines for a quasi-chronicexposure situation
8.8.3.1. Activity in foodstuffs
The Basic Safety Standards establish that ifthere is no shortage of food and there are no othercompelling social or economic factors, action levelsfor the withdrawal and substitution of specific sup-plies of food and drinking water which have beencontaminated with radioactive substances should bebased on the guidelines for foodstuffs in internationaltrade established by the Codex Alimentarius Com-mission (CAC) [58]. These are included in the BasicSafety Standards as recommended generic action lev-els for activity in foodstuffs. The levels are limitedto radionuclides usually considered relevant to emer-gency exposure situations. They include, however, allthe relevant radionuclides for the situation prevailingin Bikini Atoll (see Table XVIII).
34
TABLE XVIII. GENERIC ACTION LEVELS FOR FOODSTUFFSa
Radionuclide
134Cs, 137Cs,103Ru, 106Ru,89Sr, 131I
90Sr
241 Am,238Pu, 239Pu
Foods destined forgeneral consumption
(kBq/kg)
1
0.1
0.01
Radionuclide
134Cs, 137Cs,103Ru, 106Ru,89Sr
131I, 90Sr
241 Am,238Pu, 239Pu
Milk, infant food anddrinking water
(kBq/kg)
1
0.1
0.001
a For practical reasons, the criteria for separate radionuclide groups will be applied indepen-dently to the sum of the activities of the radionuclides in each group.
The levels are recommended for use by nationalauthorities as the generic action levels in their emer-gency plans unless there are strong reasons for adopt-ing substantially different values. Use of these inter-nationally recognized levels by national authoritieswould have the considerable advantage of helpingto retain public confidence and trust. Moreover, theuse of such values helps to prevent anomalies thatotherwise might occur between neighbouring coun-tries. When a foodstuff is exported from a country,it must meet certain standards in order that it maybe exempted from any further monitoring or controlby the receiving country and any subsequent receiv-ing countries. Thus, the internationally agreed stan-dards established by the CAC are essential in orderthat international trading in food is not severely dis-rupted by excessive monitoring, administrative andlegal requirements.
The CAC's action levels for activity concentra-tion in foodstuffs are conceptually 'non-action' levels.This means that the residual individual doses fromthe consumption of foodstuffs showing such levels areconsidered acceptable without any actions to be takento reduce the levels.
Depending on the annual 'food basket' [59] ofthe population, the doses resulting from the CAC'slevels will vary, but — with the FAO figure for totalfood consumption of 550 kg per year (not includingdrinking water) — the consumption of food of whichevery component had activity concentrations at theCAC action levels would result in a maximum annualcommitted effective dose of up to about 10 mSv. Thisfigure assumes that the food basket is contaminatedto the full CAC values for the whole year.
8.8.4. Guidelines for a chronicexposure situation
The Basic Safety Standards establish that,in the case of a chronic exposure situation, reme-dial actions are not normally likely to be necessaryunless relevant (generic) action levels are exceeded.As stated earlier, an action level is a level of doserate or activity concentration above which remedialor protective actions should be undertaken to protectpeople; generally, they are specified separately for dif-ferent remedial actions. The Basic Safety Standardsestablish action levels only for the case of exposureto radon in air for both dwellings and workplaces. Asthe former involves members of the public, it couldbe used as a sound reference for other generic chronicexposure situations involving the public.
8.8.4-1- Radon in dwellings
The Basic Safety Standards establish that theoptimized action levels for remedial action relatingto chronic exposure situations involving radon indwellings should, in most situations, fall within ayearly average concentration of 200-600 Bq-m~3 of222Rn in air. The conversion coefficient establishedin the Basic Safety Standards for the annual expo-sure to the progeny of 222Rn per unit 222Rn concen-tration is 1.56 x 10~2 mJ-h-m~3 per Bq-m~3, andthe coefficient for the dose conversion for exposure indwellings is 1.1 mSv per mJ-h-m~3. Thus, the opti-mized action level for radon in dwellings can be trans-lated approximately to an annual effective dose ofabout 3 to 10 mSv.
35
TABLE XIX. ANNUAL EFFECTIVE DOSES TOADULTS FROM NATURAL SOURCES
Source of exposure
Cosmic rays
Terrestrial gamma rays
Radionuclides in the body(except radon)
Radon and itsdecay products
Total (rounded)
Globalaverage
exposure(mSv)
0.39
0.46
0.23
1.3
2.4
Typicalelevatedexposure
(mSv)
2.0
4.3
0.6
10
—
8.8.5. Reference for comparison:Doses due to naturalbackground radiation
As stated earlier, the worldwide average annualdose incurred by the global population as a resultof radiation from natural sources is estimated to be2.4 mSv [30, 52], of which about half is mainly dueto cosmic and terrestrial background radiation andhalf is due to exposure to 222Rn. There is, however, alarge variability in the annual effective doses causedby natural sources. It is common to find large regionswith exposures elevated by up to an order of mag-nitude and smaller regions with even higher levels.Table XIX indicates, in addition to the global aver-age exposures referred to in Table XII, typical ele-vated values of annual effective doses to adults fromnatural sources. The elevated values are representa-tive of large regions, but much higher atypical valuesmay occur locally.
The effective dose rate caused by cosmic radi-ation depends on the height above sea level and thelatitude. The annual effective doses in areas of highexposure (locations at higher elevations) are aboutfive times the average. The terrestrial effective doserate depends on local geology, with a high level typ-ically being about ten times the average; the effec-tive dose to communities living near some types ofmineral sand may be up to about 100 times the aver-age. The effective dose from radon decay productsdepends on the local geology and housing construc-tion and use, with the dose in some regions being
about ten times the average. Local geology and thetype and ventilation of some houses may combine togive effective dose rates from radon decay productsof several hundred times the average. A range of theworldwide annual effective dose from natural sourceswould be 1-20 mSv, with values in some regions of theorder of 30-50 mSv and high levels of above 100 mSv.
In summary, although the global averageannual effective dose due to natural background radi-ation is of the order of a few millisieverts, annual effec-tive doses of about 10 mSv are not unusual and veryhigh annual effective doses of up to about 100 mSvare found in some places. As national authoritieshave considered these situations and decided not totake protective actions against typical elevated back-ground levels, it appears that doses caused by theselevels can be used as another reference for decidingon interventions under chronic exposure situations.
8.9. GENERIC GUIDANCE FORREHABILITATION OF AREASOF CHRONIC EXPOSURE
From the earlier discussion it appears that anannual effective dose of up to about 10 mSv can beused as a generic guideline for action levels aimedat considering protective remedial actions for reha-bilitating areas subject to chronic exposure, such asthe areas with residual radionuclides from nuclearweapon testing in Bikini Island. For doses below theguidance action levels, the situation could, after con-sideration, be taken as being generally safe for thepopulation.
It is emphasized, however, that this generi-cally acceptable action level of annual dose does notimply that below such a level it is never worthwhileto reduce the radiation exposure. If it is justified onradiological grounds, intervention for the purposes ofradiological protection should always be undertaken,and the form, scale and duration of the interventionwould be determined by a process of optimization ofprotection.
In addition, it is essential to keep in mindthat there are levels of equivalent dose and of effec-tive dose at which intervention would almost alwaysbe justified on radiological grounds. As indicatedbefore, the Basic Safety Standards implicitly indicatethat an annual effective dose of several tens of mil-lisieverts would almost always justify some kind ofintervention.
36
A generic action level of up to about 10 mSv perannum is therefore applicable to the chronic exposuresituation on Bikini Island and has been used in thereview as the basis for judging the prospects for reset-tlement and — should resettlement be decided on bythe population concerned — the required remedialactions.9
One problem is whether it is the doses causedby the residual radionuclides or the total dose (includ-ing natural background doses) that should be com-pared with the action level. In theory only theavertable dose must be considered. In the situationat Bikini Atoll by far the largest doses (doses dueto residual activity and those due to natural radio-
nuclides) are incurred through the ingestion path-way. Therefore, any planned remedial action should.be expected to affect the diet — or more preciselythe activity in the diet — and thus change the con-tribution of both residual and natural radionuclides.However, the remediation strategies considered inthis review only assess the decrease of doses due tothe residual radionuclides and this will be used asthe main reference for judgement. The natural back-ground doses will be assumed to remain constant atthe current level of about 2.4 mSv and the total dose(i.e. the dose from residual radionuclides plus the nat-ural background dose) is also presented (in parenthe-ses) for reference purposes.
9 This discussion is further elaborated in recent interimguidance on the subject published by the IAEA [60].
37
9. HABITABILITY OF BIKINI ISLAND
9.1. RADIOLOGICAL ASSUMPTIONS
9.1.1. Critical group
Should the people of Bikini Atoll decide toresettle Bikini Island, it was judged that it wouldbe desirable to base intervention decisions on thelikely exposure of a hypothetical critical group liv-ing on the island and consuming a high calorie dietderived entirely from foods produced locally on theisland. This assumption is conservative and probablyunrealistic in the sense that it is more likely that,should resettlement come about, future diets wouldinclude imported foodstuffs. In fact, diets through-out the Marshall Islands nowadays have a large com-ponent of imported foodstuffs, and it seems unlikelythat the trend in this direction will be reversed in thenear future. However, it is possible that the consump-tion of locally derived foodstuffs could increase againwere the financial conditions that presently permitthe import of many foodstuffs to change in the future,and it is conceivable that some of the Bikinian com-munity might be obliged to readopt an exclusivelytraditional locally derived diet.
Evidence of the conservative nature of the cur-rent diet assumption comes from studies on Rongelapand Utirik Atolls, where 137Cs body burden estimatesbased on the mixed diet and local food only dietwere compared with actual whole body measurementsof 137Cs in the two populations. The study showedthat a mixed diet of local plus imported food comesmuch closer to predicting the current body content of137 Cs than the local food only diet models (see Figs 7and 8) [61].
9.1.2. Radiation doses
On the assumption that the critical group con-sumes a high calorie diet of only locally producedfoodstuffs, the annual effective dose to the criticalgroup has been assessed (see Section 7) to be about15 mSv (or 17.4 mSv if natural background doses wereto be included) — higher than the generic action levelof an annual effective dose of up to about 10 mSv.There is, therefore, strong justification for explor-ing possible remediation strategies for reducing thepotential radiation exposure of a population reset-tling Bikini Atoll under the presumed diet conditions.
12 24 36 48 60Time (months since 1977)
72 84
A Whole body measurementso Local food, high calorie diet
• Local food, low calorie diet• Local + imported food diet
FIG. 7. Comparison of the estimated activity of1S7Cs inthe body from different environmental models with datafrom whole body measurements of 137 Cs for residents ofRongelap Island.
50 100 150 200
Time (months since 1977)
A whole body measurements • Local food, low calorie dieto Local food, high calorie diet • Local + imported food diet
FIG. 8. Comparison of the estimated activity of 1S7 Cs inthe body from different environmental models with datafrom whole body measurements of 137 Cs for residents ofUtirik Island.
38
Second applicationof fertilizer
24 84 96 10836 48 60 72Months since February 1985
FIG. 9. Reduction of1S7Cs levels in drinking coconuts at Bikini Island after initial and second applications of potassiumfertilizer [62]. (A: KCl application — 1000 kg/ha, two treatments; B: KCl + NP fertilizer application — 1000 kg/ha, twotreatments; C: no application of K; D: KCl application — 2000 kg/ha, one treatment; E: KCl application — 2000 kg/ha,two treatments; F: KCl + NP fertilizer application — 2000 kg/ha, two treatments.)
It should be noted, however, that on the same pre-sumption the total lifetime dose to be received by peo-ple returning has been estimated to be about 350 mSv(see Section 7), i.e. lower than the generic guidancelevel for permanent resettlement given in the BasicSafety Standards.
9.2. POSSIBLE REMEDIAL MEASURES
Several remedial methods to reduce the dosefrom 137Cs at Bikini Island have been evaluated overthe years. These include:
— Irrigation of the soil with large quantities of saltwater for the purpose of leaching the 137Cs fromthe soil,
— Addition of binding agents such as illite and zeo-lites to trap the 137Cs and make it unavailable forplant uptake,
— .Cropping and disposal of vegetation to remove137Cs accumulated in plants,
— Excavation and disposal of the top 40 cm of thesoil column that generates most of the activity onthe island,
— Treatment of the soil with high potassiumfertilizers.
Of these methods, the latter two, soil removaland treatment with potassium, have been foundto be the most effective and attention has- subse-quently been focused on these two alternative remedialstrategies.
9.2.1. Soil removal
The removal of the top 40 cm of soil from BikiniIsland would be effective in reducing radiation expo-sure due to 137Cs and other residual radionuclides inthe terrestrial environment. It is estimated to reducethe projected annual effective dose due to weapontest residues to below 0.1 mSv (to which the annualeffective dose of 2.4 mSv due to natural background
39
radiation must be added). It is noted, however, thatnatural activity levels of the local topsoil are very lowin comparison with those of soil generally, particu-larly of continental soil. If the topsoil on Bikini Islandwere to be replaced by soil brought in from outsidethe Marshall Islands, the annual effective dose due tonatural background radiation would consequently beexpected to increase.
Soil removal is stated to be the option favouredby the Bikinians. However, the removal of hundredsof thousands of tonnes of soil could have adverseenvironmental and social consequences, especiallybecause the tree crops that constitute the naturalfood supply require the fertile topsoil. Removal ofthe topsoil would necessitate removing some 30 000mature coconut trees and breadfruit, pandanus andpapaya trees. It would be an enormous — and proba-bly prohibitively expensive — undertaking to replen-ish this resource, either by restoring the topsoil overtime or by replacing it with fresh soil from elsewhere.
The detailed assessment of the environmentaland social consequences of this particular remediationstrategy is beyond the scope of the present review.
9.2.2. Soil treatment with potassiumfertilizer
The treatment of local soil with potassium fer-tilizer has been shown in experiments to be veryeffective in reducing the uptake of 137Cs into ediblefoods [62]. Results from one of several field trials atBikini Island are shown in Fig. 9 [62]. A reductionof 137Cs concentrations in coconut milk (and manyother food items) to 5% of their original values hasbeen achieved in several experiments. The reducedconcentration of 137Cs persists for nearly five yearsafter the application of potassium fertilizer is termi-nated and the subsequent increase in uptake of 137Csis very slow (see Fig. 9). Subsequently, application ofpotassium fertilizer is likely to be needed every fouror five years to maintain the 137Cs activity levels inlocal foods and until radioactive decay reduces theactivity to insignificant levels.
Two other potentially significant exposurepathways under present conditions are external expo-sure to the gamma radiation emitted by 137Cs andpossible ingestion or inhalation of plutonium andamericium in the soil in dwelling areas. Thus, a fur-ther component of the remediation strategy couldbe the removal of surface soil to a depth of 30 cmwhere the village will be established and from aroundeach housing site, and its replacement with a layer
16.00
_ 14.00
$> 12.00
^ 10.00
•§ 8.00<D•| 6.00
^ 4.00
2.00
0
14.75
Local high calorieintake diet
]: Current conditions
Local and importedfood diet
: After remediation
FIG. 10. Predicted radiation doses before and after reme-diation.
of crushed coral to minimize external exposure andpossible ingestion from the remaining soil.
An alternative to the removal of soil from theliving areas is a process employed successfully in theaftermath of the Chernobyl accident, whereby theuppermost 30-50 cm of soil is turned over so that itis buried and replaced by deeper soil, which is muchless contaminated. This would avoid the problem ofsoil disposal, but would require that, should crops beraised in the living areas, the same potassium fertil-izer treatment be applied as for the rest of the landwhere domestic crops are grown.
Treating the soil over most of the island wherefood crops are grown with fertilizer (either as a mixedfertilizer or as potassium chloride, KC1) would reducethe 137Cs concentration in foods and thereby reducethe internal dose via the ingestion pathway. Addi-tionally, the removal of the surface soil in the areaof housing and villages, where people spend most oftheir time, would reduce the external gamma wholebody exposure from 137Cs, the skin dose from betaand alpha emitters and the potential dose from theingestion of soil. This combination of remedial actionsis estimated to reduce doses by a factor of nearly 10from pretreatment levels [20].
Consideration has been given to the potentialecological effects of the proposed potassium fertilizertreatment on Bikini Island. At the planned levels ofpotassium treatment there seems to be no possibilityof altering significantly the soil chemistry and, fur-thermore, the transfer of potassium to groundwaterhas been found to be very low [8].
After potassium treatment of the soil in areaswhere food crops are grown, together with replace-ment of soil from around the living areas, the esti-mated dose rate from the consumption of an entirely
40
TABLE XX. RADIONUCLIDE ACTIVITIES'1 PER UNIT WET WEIGHT(Bq/g) FOR LOCAL FOODSTUFFS ON BIKINI ISLAND AFTER REMEDIATION [20]
Local foodstuffs
Reef fishTunaMahi mahiMarine crabsLobsterClamsTrochusTcidacna muscleJedrulCoconut crabsLand crabsOctopusTurtleChicken muscleChicken liverChicken gizzardPork musclePork kidneyPork liverPork heartBird muscleBirds' eggsChicken eggsTurtle eggsPandanus fruitPandanus nutsBreadfruitCoconut juiceCoconut milkTuba/jekeroDrinking coconutCopra meatSprouting coconutMarshallese cakePapayaSquashPumpkinBananaArrowrootCitrusRain waterWell waterMaloloCoffee/teaSoilb
SoiF
137Cs
2.9 x 1(T3
4.5 x 1(T3
4.5 x 1(T3
1.4 x 1(T3
1.4 x 1<T3
4.6 x l<r4
4.6 x 1(T4
4.6 x 1(T4
4.6 x 1(T4
3.7 x 10-1
3.7 x HT1
1.8 x 1(T3
2.8 x 1(T4
2.1 x 1(T2
2.1 x 1(T2
2.1 x 10~2
1.6 x 10°1.4 x 10°
8.1 x KT1
9.8 x HP1
2.5 x 1CT3
6.7 x 1(T4
2.1 x 1(T2
2.8 x 1(T4
1.9 x Itr1
1.9 x ID"1
1.9 x 1(T2
5.8 x 1(T2
2.7 x HT1
2.7 x HT1
1.5 x HT1
2.7 x HT1
2.7 x 1Q-1
2.7 x ID"1
1.1 x 10"1
5.9 x 10~2
5.9 x 10~2
8.9 x 1(T3
5.4 x 1(T2
6.0 x ID"3
4.3 x 1(TS
4.5 x 10~3
4.3 x ID"5
4.3 x 1(TS
3.9 x 1Q-1
90Sr
4.5 x 1(T5
5.3 x 1(T6
5.3 x 10~6
8.9 x 1(T5
8.9 x 1Q~5
8.7 x 1(TS
8.7 x 1(T5
8.7 x 10~s
8.7 x 10~s
5.2 x 10~2
5.2 x 10~2
4.5 x HP5
4.5 x 10~5
1.5 x 1(T3
1.5 x 1(T3
1.5 x 10~3
1.5 x 10~3
6.2 x 10~3
2.9 x 1CT3
1.5 x 10~3
2.3 x 1(T4
3.6 x 1CT4
1.5 x 10~3
4.5 x 1(T5
1.2 x 1Q-1
1.2 x HT1
6.9 x 1(T2
4.5 x 10~4
3.2 x 1(T3
3.2 x 10~3
5.9 x NT3
3.2 x 1(T3
3.2 x 1(T3
3.2 x 10~3
4.9 x 10~2
6.8 x 1<T2
6.8 x l<r2
4.9 x ID"2
6.8 x 1(T2
4.9 x 10~2
1.4 x 1(T5
1.2 x 1(T3
1.4 x 10~6
1.4 x 1(T5
9.9 x 1Q-1
7.3 x KT1
239+240pu
1.3 X 1CT5
1.9 x 10~6
1.9 x 1(T6
3.6 x 1(T5
3.6 x 10~5
8.3 x 1(T4
8.3 x 10~4
8.3 x 1(T4
8.3 x 1(T4
3.8 x 10~5
3.8 x 1(T5
1.3 x 10~6
1.3 x 1<T5
7.7 x 1(T6
7.7 x 10~6
7.7 x 1(T6
7.7 x ID"6
3.5 x 1(T5
1.2 x 1(T4
5.9 x 10~6
1.3 x 10~5
1.3 x 10-5
7.7 x 1(T6
1.3 x 1(T5
3.2 x 10~6
3.2 x 1(T6
1.8 x ID"6
1.0 x 1(T6
1.9 x HT6
1.9 x 10~6
2.7 x 10~6
1.9 x 10~6
1.9 x 1(T6
1.9 x 1(T6
2.5 x ID"6
2.2 x 1(T5
2.2 x 10~5
2.5 x 1(T6
2.2 x 1(T5
2.5 x 10~6
3.3 x 1(T7
6.1 x 10-7
3.3 x 1(T7
3.3 x 1(T7
2.0 x ID"1
5.5 x 10~2
241 Am
6.5 x 10~6
1.3 x 10~6
1.3 x 10~6
2.6 x 10~5
2.6 x 10~5
4.6 x ID"4
4.6 x 10~4
4.6 x 10~4
4.6 x 10~4
2.8 x 10~5
2.8 x 10~5
6.5 x 10~6
6.5 x 10~6
6.0 x 10~6
6.0 x HT6
6.0 x 10~6
6.0 x 10~6
1.2 x HP5
5.2 x 10~5
1.8 x KT5
6.5 x NT6
6.5 x 10~6
6.0 x 10~6
6.5 x 10~6
3.8 x HT6
3.8 x 10~6
1.2 x 10~6
8.5 x 10~6
1.1 x 1Q-6
1.1 x 10~6
3.6 x 10~6
1.1 x 10~6
1.1 x KT6
1.1 x ID"6
3.6 x 10~7
3.0 x 10~6
3.0 x 10"6
3.6 x 10~7
3.0 x 10~6
3.6 x 1Q-7
3.7 x 10~8
4.4 x 10~7
3.7 x ID"8
3.7 x 1Q-8
1.2 x 10"1
4.7 x KT2
a Decay corrected to 1999.b Soil represents the current conditions on Bikini Island, Bq/g dry weight.0 Soil represents the option of soil removal and potassium fertilizer treatment for Bikini Island,
Bq/g dry weight.
41
locally derived diet is significantly reduced: theannual effective dose estimate of 15 mSv (or 17.4 mSvif natural background doses are added; see Section7) is, after remediation, estimated to be reduced to1.2 mSv (or 3.6 mSv if natural background doses areadded). The mixed diet of imported plus local foods,which resulted in an annual effective dose estimateof 4 mSv without remediation (or 6.4 mSv if dosesdue to the natural background radiation are added),would — after the same remediation — result in adose of 0.4 mSv (or 2.8 mSv if natural backgrounddoses are added) (Fig. 10).
An uncertainty analysis of these dose predic-tions [63] indicates that the estimated maximumuncertainty is a factor of 2 in either direction, whichis considered to be acceptable in the present context.
9.3. CONDITIONS FOR HABITABILITY
From the evidence presented it seems thateither of the treatment strategies considered, i.e.total topsoil removal and potassium treatmentplus localized soil removal, would be effective inreducing the annual doses to well below the genericaction level of annual effective dose of up to about
10 mSv and, therefore, would establish appropriateradiation protection conditions for the resettlementof Bikini Island.
Because of the reservations expressed earlierconcerning the total soil removal option, potassiumtreatment together with localized soil removal is thepreferred strategy.
9.4. ACTIVITY LEVELS IN FOODSTUFFS
As discussed earlier, international guidelines forthe specific activity of radionuclides in foodstuffs areestablished in the Basic Safety Standards. Predictedradionuclide activities for local foodstuffs on BikiniIsland following the preferred remediation measuresare shown in Table XX.
Several food products under current conditionsat Bikini Island (with no potassium fertilizer treat-ment) do exceed the guideline for 137Cs; for the otherradionuclides (90Sr, 239+240pu and 24iAm) the food.stuffs are all already well below the guideline lev-els (see Tables VII-X). After treatment with potas-sium fertilizer, the 137Cs concentration in these foodgroups would also be reduced to well below the guide-line levels.
42
10. CONCLUSIONS AND RECOMMENDATIONS
1. On the basis of the amount and quality of thescientific information on the residual radionuclidesfrom nuclear weapon testing at Bikini Atoll submit-ted for review, it is concluded that:
No further independent corroborationof the measurements and assessmentsof the radiological conditions at BikiniAtoll is necessary.
This conclusion is based on: the excellent qual-ity control of those measurements and assessments;the regular participation in intercomparison pro-grammes by the various scientific groups that car-ried out those measurements and assessments; andthe good agreement among the data submitted.Nevertheless, it is acknowledged that the Bikinianpeople have concerns about the actual radiologicalconditions in their homeland, and it is therefore con-sidered that:
The Bikinians might be reassured aboutthe actual radiological conditions atBikini Atoll by a limited programmeof monitoring of radiation levels, whichshould involve some participation bymembers of the community.
2. In view of the information submitted andunder the assumption that the Bikinian communitydecides to resettle Bikini Island (the main island ofresidence at Bikini Atoll), it is concluded that:
Permanent resettlement of Bikini Islandunder the present radiological condi-tions without remedial measures is notrecommended in view of the radiationdoses that could potentially be receivedby inhabitants with a diet of entirelylocally produced foodstuffs.
This conclusion was reached on the basis that a dietmade up entirely of locally produced food — whichwould contain some amount of residual radionuclides— could lead the hypothetical resettling populationto be exposed to radiation from residual radionu-clides in the island, mainly from 137Cs, resulting inannual effective dose levels of about 15 mSv (if thedose due to natural background radiation were added,
this would result in an annual effective dose of about17.4 mSv). This level was judged to require interven-tion of some kind for radiation protection purposes.
3. However, it is considered that:
In practice, doses caused by a diet oflocally derived foodstuffs are unlikely tobe actually incurred under the currentconditions, as the present Marshallesediet contains — and would in the nearfuture presumably continue to contain— a substantial proportion of importedfood which is assumed to be free ofresidual radionuclides.
Nevertheless, the hypothesis of a diet of solely locallyproduced food was adopted in the assessment forreasons of conservatism and simplicity, and alsobecause the present level of imports of foodstuffscould decrease in the future.
4. A number of straightforward environ-mental remediation strategies at Bikini Island havebeen considered, which, if properly implemented,would achieve very satisfactory results from the pointof view of radiation protection. It is therefore con-cluded that:
Provided that certain remedial mea-sures are taken, Bikini Island could bepermanently reinhabited.
5. Several possible remediation strategies wereconsidered with the result that the following wereselected as a basis for further assessment:
— The periodic application of potassium basedfertilizer to all areas of Bikini Island whereedible crops may be grown, supported by theremoval of soil from around and beneath thedwelling areas and its replacement by crushedcoral (known as the potassium fertilizer remedi-ation strategy);
— The complete removal of the topsoil from BikiniIsland (called the soil scraping remediationstrategy).
43
While no definite recommendations aregiven on which strategy to follow, itis considered that the strategy usingpotassium fertilizer is the preferredapproach.
In this connection, it was noted that the soils of BikiniAtoll are extremely deficient in potassium and exten-sive field trials have demonstrated that the applica-tion of potassium rapidly reduces the concentrationof 137Cs in food crops since potassium is taken upby the plants in preference to caesium. The reduc-tion of 137Cs in the food crops is sustained for aboutfour to five years, after which the values slowlybegin to increase again. However, repeated applica-tion of fertilizer forms an effective strategy in reduc-ing the estimated doses to the potential inhabitantsof Bikini Island. Furthermore, the supporting strat-egy of removing soil from dwelling areas would elimi-nate most of the external and internal exposures fromdirect soil ingestion or inhalation.
6. It is concluded that:
The results expected from the potas-sium fertilizer remediation strategy areconsistent with international guidanceon interventions to avoid dose in chronicexposure situations and, therefore, thisstrategy would provide a radiologicallysafe environment permitting early reset-tlement.
Depending on the assumptions made concerning diet,the annual calculated mean effective doses would bereduced as follows: from about 15 mSv (if the dosedue to natural background radiation were added, thiswould result in an annual effective dose of about17.4 mSv), for a high calorie diet of totally local food-stuffs, to about 1.2 mSv (if the dose due to naturalbackground radiation were added, this would resultin an annual effective dose of about 3.6 mSv); andfrom about 4 mSv (if the dose due to natural back-ground radiation were added, this would result in anannual effective dose of about 6.4 mSv), for a highcalorie diet of both local and imported foodstuffs,to about 0.4 mSv (if the dose due to natural back-ground radiation were added, this would result in anannual effective dose of about 2.8 mSv). Even forthe more conservative assumption of a high caloriediet of totally locally produced foodstuffs, the result-ing doses will be far below acceptable generic action
levels for intervention. The doses will be somewhathigher than those due to natural background radia-tion that were incurred by the inhabitants of BikiniIsland before the evacuation and prior to when thenuclear weapon tests took place, and also somewhathigher than global average natural background doses,but lower than typical elevated levels of natural back-ground doses around the world.
7. The conclusion is that:
The alternative strategy, i.e. the soilscraping remediation strategy — statedto be the alternative preferred by theBikinians — would be very effective inavoiding doses caused by the residualradionuclides, but it could entail seriousadverse environmental and social conse-quences.
The consequences may be serious because the fertiletopsoil supports the tree crops, which are the majorlocal food resource. The replacement of the soil withtopsoil from elsewhere would be an enormous under-taking which is likely to be prohibitively expensive.The content of natural radionuclides in any continen-tal soil used as replacement soil would most probablyexceed that of the present soil.
8. It is concluded that:
No remedial actions should be proposedat this stage for the islands of BikiniAtoll other than Bikini Island.
The other islands have historically been non-residential and used only for occasional visits and forfishing.
9. On the assumption that the proposed reme-diation strategy is undertaken, it is further recom-mended that:
Regular measurements of activity inlocal foodstuffs should be made to assessthe effectiveness of the measures taken.A simple, local whole body monitor andtraining in its use should be providedas a further means of enabling potentialinhabitants to satisfy themselves thatthere is no significant uptake of caesiuminto their bodies.
44
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[3] BIKINI ATOLL REHABILITATION COMMIT-TEE, Resettlement of Bikini Atoll: Feasibility andEstimated Cost of Meeting the Federal RadiationProtection Standards, Rep. No. 1, submitted to theUS Congress, House and Senate Committees on Inte-rior Appropriations, pursuant to Public Law 97-257(15 November 1984).
[4] BIKINI ATOLL REHABILITATION COMMIT-TEE, Resettlement of Bikini Atoll: Feasibility andEstimated Cost of Meeting the Federal RadiationProtection Standards, Interim Report, submitted tothe US Congress, House and Senate Committees onInterior Appropriations, pursuant to Public Law 97-257 (23 November 1983).
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[6] UNITED STATES DEPARTMENT OF ENERGY,United States Nuclear Tests, July 1945 throughSeptember 1992, Rep. DOE/NV-209, Rev. 14,USDOE Nevada Operations Office, Las Vegas, NV(1994).
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[10] MILTENBERGER, R.P., GREENHOUSE, N.A.,LESSARD, E.T., Whole body counting results from1974 to 1979 for Bikini Island residents, Health Phys.39 (1980) 395-507.
[11] KLEMM, J., GOETZ, J., PHILLIPS, J., THOMAS,C., Analysis of Radiation Exposure to Service Per-sonnel on Rongerik Atoll, Operation Castle, ShotBravo, SAIC-86/1608, Science Applications Interna-tional Corp., La Jolla, CA (1986).
[12] KUMATORI, T., et al., "Follow-up studies over a 25-year period on the Japanese fishermen exposed to
radioactive fallout in 1954", The Medical Basis forRadiation Accident Preparedness, Elsevier—NorthHolland, New York (1980) 33-54.
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[16] ROBISON, W.L., CONRADO, C.L., EAGLE, R.J.,STUART, M.L., The Northern Marshall IslandsRadiological Survey: Sampling and Analysis, Sum-mary, Rep. UCRL-52853, Part 1, Lawrence Liver-more National Laboratory, Livermore, CA (1981).
[17] ROBISON, W.L., NOSHKIN, V.E., PHILLIPS,W.A., EAGLE, R.J., The Northern Marshall IslandsRadiological Survey: Radionuclide Concentrations inFish and Clams and Estimated Doses via the MarinePathway, Rep. UCRL-52853, Part 3, Lawrence Liv-ermore National Laboratory, Livermore, CA (1981).
[18] ROBISON, W.L., et al., An Updated Assessmentof Bikini and Eneu Islands at Bikini Atoll, Rep.UCRL-53225, Lawrence Livermore National Labora-tory, Livermore, CA (1980).
[19] ROBISON, W.L., et al., The Northern Mar-shall Islands Radiological Survey: Terrestrial FoodChain and Total Doses, Rep. UCRL-52853, Part4, Lawrence Livermore National Laboratory, Liver-more, CA (1982).
[20] ROBISON, W.L., BOGEN, K.T., CONRADO, C.L.,An Updated Assessment for Resettlement Optionsat Bikini Atoll — A U.S. Nuclear Test Site, HealthPhys. 73 1 (1997) 100-114.
[21] KEHL, S.R., MOUNT, M.E., ROBISON, W.L.,The Northern Marshall Islands Radiological Sur-vey: A Quality Control Program for Radiochemicaland Gamma Spectroscopy Analysis, Rep. UCRL-ID-120429, Lawrence Livermore National Laboratory,Livermore, CA (1995).
[22] ROBISON, W.L., et al., The Northern MarshallIslands Radiological Survey: Data and Dose Assess-ments, Health Phys. 73 1 (1997) 37-48.
[23] McEWAN, A.C., BAVERSTOCK, K.F.,PARETZKE, H.G., SANKARANARAYANAN, K.,TROTT, K.R., The Scientific Advisory Panel tothe Nationwide Radiological Study, Findings of the
45
Nationwide Radiological Study, Summary Report,prepared for the Cabinet of the Government of theRepublic of the Marshall Islands, Majuro (December1994).
[24] SIMON, S.L., GRAHAM, J.C., Findings of the firstcomprehensive radiological monitoring program ofthe Republic of the Marshall Islands, Health Phys.73 1 (1997) 66-85.
[25] FOOD AND AGRICULTURE ORGANIZATIONOF THE UNITED NATIONS, INTERNATIONALATOMIC ENERGY AGENCY, INTERNATIONALLABOUR ORGANISATION, OECD NUCLEARENERGY AGENCY, PAN AMERICAN HEALTHORGANIZATION, WORLD HEALTH ORGANI-ZATION, International Basic Safety Standards forProtection Against Ionizing Radiation and for theSafety of Radiation Sources, Safety Series No. 115,IAEA, Vienna (1996).
[26] PARETZKE, H., personal communication, 1996.[27] BALOS, H., Opening statement before the IAEA
Advisory Group Meeting to peer review recommen-dations concerning the radiological conditions in theRepublic of the Marshall Islands, Vienna, 11 Decem-ber 1995.
[28] BLIX, H., Opening statement before the IAEA Advi-sory Group Meeting to peer review recommendationsconcerning the radiological conditions in the Repub-lic of the Marshall Islands, IAEA, Vienna, 11 Decem-ber 1995.
[29] UNITED NATIONS, Sources, Effects and Risksof Ionizing Radiation (1988 Report to the Gen-eral Assembly), Scientific Committee on the Effectsof Atomic Radiation (UNSCEAR), UN, New York(1988).
[30] UNITED NATIONS, Sources and Effects of IonizingRadiation (1993 Report to the General Assembly),Scientific Committee on the Effects of Atomic Radi-ation (UNSCEAR), UN, New York (1993).
[31] TILL, J.E., et al., The Utah thyroid cohort study:Analysis of the dosimetry results, Health Phys. 68 4(1995) 472-483.
[32] LESSARD, E., et al., Thyroid Absorbed Dose forPeople of Rongelap, Utirik and Sifo on March 1,1954, Rep. BNL-51882, UC-48, Safety and Envi-ronmental Protection Division, Brookhaven NationalLaboratory, Upton, NY (1985).
[33] ROBISON, W.L., CONRADO, C.L., STUART,M.L., Radiological Conditions at Bikini Atoll:Radionuclide Concentrations in Vegetation, Soil,Animals, Cistern Water, and Ground Water, Rep.UCRL-53840, Lawrence Livermore National Labora-tory, Livermore, CA (1988).
[34] SHINN, J.H., HOMAN, D.N., ROBISON, W.L.,Resuspension Studies at Bikini Atoll, Rep. UCID-18538, Rev. 1, Lawrence Livermore National Labo-ratory, Livermore, CA (1989).
[35] SHINN, J.H., ROBISON, W.L., HOMAN, D.N.,Resuspension studies in the Marshall Islands, HealthPhys. 73 1 (1997) 248-257.
[36] NOSHKIN, V.E., WONG, K.M., EAGLE, R.J.,JOKELA, T., Levels and distributions of severalradionuclides in Bikini lagoon sediment (to be pub-lished).
[37] ROBISON, W.L., Estimates of the RadiologicalDose to People Living on Bikini Island for TwoWeeks While Diving In and Around the SunkenShips in Bikini Lagoon, Rep. UCRL-ID-104916,Lawrence Livermore National Laboratory, Liver-more, CA (1990); and Appendix III, in Archeology ofthe Atomic Bomb, A Submerged Cultural ResourcesAssessment of the Sunken Fleet of Operation Cross-roads at Bikini and Kwajalein Atoll Lagoons, Sub-merged Cultural Resources Unit, National MaritimeInitiative, United States Department of the InteriorNational Park Service, Southwest Cultural ResourcesCenter Professional Papers No. 37, Santa Fe, NM(1991).
[38] NOSHKIN, V.E., WONG, K.M., EAGLE, R.J.,ROBISON, W.L., "Comparative concentrations ofCs, Sr, Pu and Am in tissues offish from the MarshallIslands and calculated dose commitments from theirconsumption", Environmental Research on ActinideElements (Proc. Conf. Hilton Head, SC, 1983) (PIN-DAR III, J.E., ALBERTS, J.J., McLEOD, K.W.,SCHRECKHISE, R.G., Eds), Rep. CONF-841142,(DE86008713), Office of Health and EnvironmentalResearch, US Department of Energy, Washington,DC (1987) 391-127.
[39] NOSHKIN, V.E., WONG, K.M., EAGLE, R.J.,JOKELA, T.A., BRUNK, J.A., Radionuclide Con-centrations in Fish and Invertebrates from BikiniAtoll, Rep. UCRL-53846, Lawrence LivermoreNational Laboratory, Livermore, CA (1989).
[40] NEVISSI, A., SCHELL, W.R., Distribution of pluto-nium and americium in Bikini Atoll lagoon, HealthPhys. 28 (1975) 539-547.
[41] SCHELL, W.R., WATTERS, R.L., Plutonium inaqueous systems, Health Phys. 29 (1975) 589-597.
[42] SCHELL, W.R., LOWMAN, F.G., MARSHALL,R.P., "Geochemistry of transuranic elements atBikini Atoll", Transuranic Elements in the Environ-ment (HANSEN, W.C., Ed.), Rep. DOE/TIC-22800,Technical Information Center, US Department ofEnergy, Oak Ridge, TN (1980).
[43] NOSHKIN, V.E., "Transuranium radionuclides incomponents of the benthic environment of EnewetakAtoll", ibid., pp. 578-601.
[44] NOSHKIN, V.E., WONG, K.M., "Plutonium mobi-lization from sedimentary sources to solution in themarine environment", Marine Radioecology (Proc.3rd NBA Seminar Tokyo, 1979), OECD/NEA, Paris(1980) 729.
46
[45] MO, T., LOWMAN, F.G., "Laboratory experimentson the transfer of plutonium from marine sedimentsto seawater and to marine organisms", Radioecologyand Energy Resources (Proc. 4th Natl Symp. Corval-lis, OR, 1975) (GUSHING, C.E., Jr., Ed.), CONF-75053, Halstead Press, New York (1976).
[46] McMURTY, G.M., SCHNEIDER, R.C., COLIN,P.L., BUDDEMEIER, R.W., SUCHANEK, T.H.,Redistribution of fallout radionuclides in EnewetakAtoll lagoon sediments by callianassid bioturbation,Nature (London) 313 (1985) 674.
[47] NOSHKIN, V.E., WONG, K.M., EAGLE, R.J.,GATROUSIS, C., Transuranics and other radionu-clides in Bikini lagoon: Concentration data retrievedfrom aged coral sections, Limnol. Oceanogr. 20(1975) 729-742.
[48] NOSHKIN, V.E., WONG, K.M., EAGLE, R.J.,ROBISON, W.L., Levels and distributions of dif-ferent radionuclides in Bikini lagoon sediment (inpreparation).
[49] SUN, L.C., MOORTHY, A.R., KAPLAN, E.,BAUM, J.W., MEINHOLD, C.B., Assessment of plu-tonium exposures in Rongelap and Utirik popula-tions by fission track analysis of urine, Appl, Radiat.Isot. 46 11 (1995) 1259-1269.
[50] FRANKE, B., SCHUPFNER, R., SCHUETTEL-KOPF, K., SPENNEMANN, D.H.R., Transuranicsin bone of deceased former residents of RongelapAtoll, Marshall Islands, Appl. Radiat. Isot. 46 (1995)1253-1258.
[51] FRY, F., personal communication, 1996.[52] ROBISON, W.L., CONRADO, C.L., BOGEN,
K.T., An Updated Dose Assessment for RongelapIsland, Rep. UCRL-LR-107036, Lawrence LivermoreNational Laboratory, Livermore, CA (1994).
[53] GUDIKSEN, P.H., CRITES, T.R., ROBISON, W.L.,External Dose Estimated for Future Bikini AtollInhabitants, Rep. UCRL-51879, Rev. 1, LawrenceLivermore National Laboratory, Livermore, CA(1976).
[54] NOSHKIN, V.E., ROBISON, W.L., WONG, K.M.,The concentration of 210Po and 210Pb in the diet atthe Marshall Islands, Sci. Total Environ. 155 (1994)87-104.
[55] SIMON, S.L., GRAHAM, J.C., Dose assessmentactivities in the Republic of the Marshall Islands,Health Phys. 71 (1996) 438-456.
[56] UNITED STATES NATIONAL ACADEMY OFSCIENCES, Radiological Assessments for Resettle-ment of Rongelap in the Republic of the Mar-shall Islands, Committee on Radiological Safety inthe Marshall Islands, Board on Radiation EffectsResearch, Commission on Life Sciences, NationalResearch Council, National Academy Press, Wash-ington, DC (1994).
[57] INTERNATIONAL COMMISSION ON RADIO-LOGICAL PROTECTION, 1990 Recommendationsof the International Commission on RadiologicalProtection, Publication No. 60, Pergamon Press,Oxford and New York (1991).
[58] FOOD AND AGRICULTURE ORGANIZATIONOF THE UNITED NATIONS, WORLD HEALTHORGANIZATION, Codex Alimentarius, GeneralRequirements, Section 6.1, Guideline Levels forRadionuclides in Foods Following Accidental NuclearContamination, Joint FAO/WHO Food StandardsProgramme, Rome (1991).
[59] INTERNATIONAL ATOMIC ENERGY AGENCY,Guidelines for Agricultural CountermeasuresFollowing an Accidental Release of Radionuclides, AJoint Undertaking by the IAEA and FAO, TechnicalReports Series No. 363, IAEA, Vienna (1994).
[60] INTERNATIONAL ATOMIC ENERGY AGENCY,Application of Radiation Protection Principles tothe Cleanup of Contaminated Areas, Interim Reportfor Comment, IAEA-TECDOC-987, IAEA, Vienna(1997).
[61] ROBISON, W.L., SUN, L.C., The use of compara-tive 137Cs body burden estimates from environmen-tal data/models and whole body counting to evaluatediet models for the ingestion pathway, Health Phys.73 1 (1997) 152-166.
[62] ROBISON, W.L., STONE, E.L., The effect of K onthe uptake of 137Cs in food crops grown on coral soils:Coconut at Bikini Atoll, Health Phys. 62 6 (1992)496-511.
[63] BOGEN, K.T., CONRADO, C.L., ROBISON, W.L.,Uncertainty Analysis of an Updated Dose Assess-ment for a U.S. Nuclear Test Site — BikiniAtoll, Rep. UCRL-JC-122616, Lawrence LivermoreNational Laboratory, CA (1995).
47
Addendum
IAEA CORROBORATORY MONITORING MISSIONTO BIKINI ISLAND
A-l. INTRODUCTION
This report was presented to and discussedwith the late President of the Republic of the Mar-shall Islands, His Excellency Amata Kabua, whowas accompanied by the Honourable Thomas Kijiner,then the Republic's Minister of Health arid Environ-ment, during the President's official visit to Tokyo on14 October 1996. Immediately after this, on 17 Octo-ber 1996, the report was formally submitted to theGovernment of the Republic of the Marshall Islandsin Majuro through the requesting office, the Ministryof Foreign Affairs. The report was also presented tothe Bikinian community through the Office of theLocal Government of Kili/Bikini/Ejit in Majuro on18 October 1996. The report was finally officiallyaccepted by the Government of the Republic of theMarshall Islands through a letter from its Ambas-sador to the United States of America on 18 Septem-ber 1997.
At the meeting on 14 October 1996, Presi-dent Kabua suggested that an independent corrobo-
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ration by IAEA experts of the available environmen-tal data relating to the residual radioactive materialson Bikini Island, which had served as the basis forthe assessment contained in the main report, wouldbe desirable. That report concluded that no furtherindependent corroboration of the measurements andassessments of the radiological conditions on BikiniAtoll was necessary. However, taking into account theneed for the Bikinians to be reassured about the sit-uation, the IAEA agreed to carry out the requestedcorroboratory monitoring.
-„« TrtpH- w.,.-vv,,.,5„ .i,i,'^, ,v, j:, . _L{i^'V 'v ••' - - ' i *',' ' 'VV 1
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49
FIG. A-3. Gamma spectrometric system, for 1S7Cs measurements.
An IAEA environmental monitoring teamcarried out a limited programme of environmentalmeasurements and sampling during the period 7-22May 1997. Measurements were made of the absorbeddose rate in air and of the concentration of the mostradiologically significant radionuclides in represen-tative soil and foodstuff samples on Bikini Island.This addendum summarizes the results of the IAEAenvironmental monitoring mission.
A-2. MEASUREMENT PROGRAMME
A-2.1. Absorbed dose rate in air onBikini Island
The team made 113 measurements of theabsorbed dose rate in air (1 m above ground)at selected sites on Bikini Island (Fig. A-l). Themeasurements were made with an energy compen-sated, low dose rate Geiger-Miiller (GM) detector
(Fig. A-2) and with a radiometer with built-in GMdetectors. The locations for the measurements werechosen to give an indication of the distribution of doserates over the whole surface of Bikini Island. Accountwas also taken, in selecting measurement locations, ofprevious measurements on the island to ensure thatappropriate comparisons could be made.
A-2.2. Preliminary determination of 137Csconcentrations in selected foodstuffsand soil samples on Bikini Island
Selected food samples — coconut, pandanusand breadfruit, and soil samples (surface soil andvertical profiles) — from a number of locations onBikini Island were used for a preliminary deter-mination (screening of the samples) of 137Cs con-centrations by field gamma spectrometric equip-ment in the King Juda (provisional) laboratory onBikini Island. Two independent gamma spectromet-ric systems, with sodium iodide scintillation detectorsconnected to computerized analysers, were used.
50
Both were found to be very efficient for the rapidchecking of 137Cs concentrations in the relevant envi-ronmental samples (Fig. A-3). The counting timesranged from a few minutes to one hour, dependingon the activity concentrations of 137Cs in the samples.The detectors were not shielded because of the verylow background activity in the energy region of 137Cs(fewer than 2 counts per second), and the resultswere corrected for interference from the environmen-tal background^ radiation. On the basis of the prelim-inary field gamma spectrometric analysis (screeningof samples for 137Cs content), coconut, pandanus andbreadfruit samples as well as soil samples were col-lected for subsequent, more accurate determinationof radionuclide concentrations at the Agency's Labo-ratories in Seibersdorf, Austria.
"
FIG. A-4- Preparation of coconut fruit for measurement.
A—2.3. Collection and preparation of food-stuffs and soil samples for subsequentradiouuclide analysis at the Agency'sLaboratories
A representative number of coconut (Fig. A-4),pandanus and breadfruit samples (no papaya, pump-kin or squash samples were available on Bikini Islandat the time of the mission), topsoil (Fig. A-5) andvertical profile soil samples from different locationson Bikini Island were collected, prepared for ship-ment and shipped to the Agency's Laboratories inSeibersdorf. Some of the coconuts (coded as COC01-COC06) and corresponding soil samples were col-lected from undisturbed locations. Other coconutsamples (coded as COC08-15) and corresponding soilsamples were collected from experimental fields wherethe soil had been treated with potassium chloride(KC1) to reduce 137Cs uptake from soil to the coconutfruit. Coconut samples coded as COC16-20 were col-lected randomly from undisturbed areas. Four ver-tical soil profile samples and five topsoil samples(0-2 cm) were also collected at selected sites. Thevertical profile samples comprised six layers, 0-2,2-7, 7-12, 12-17, 17-27 and 27-37 cm, and werecoded as, for instance, COR1-1 to COR1-6. The firstlayer of the vertical profile soil samples was alwaysconsidered to be the topsoil layer. The sampling loca-tions are shown in Fig. A-6.
A—2.4. Determination of radionuclideconcentrations in foodstuffs and soilsamples at the Agency's Laboratories
All foodstuffs and soil samples from BikiniIsland were prepared for quantitative determina-tion of radionuclides at the Agency's Laborato-ries in Seibersdorf. High resolution gamma spectro-metry was used for the determination of gamma emit-ting radionuclides (mainly 137Cs) in food and soilsamples after applying appropriate preparation tech-niques, such as freeze drying and ashing for the foodsamples, and drying, grinding and sieving for the soilsamples. The alpha emitting radionuclides (239+240pu
and 241Am) were determined by alpha spectrometry *following specific radiochemical procedures, and 90Srwas determined by liquid scintillation counting afterchemical separation from other radionuclides in thesamples. For the determination of 239+240pu,
241Amand 90Sr, six soil samples were selected, four from thevertical profiles and two from the topsoil samples. For
51
. .4-5. Collection of topsail samples.
quality control (QC) purposes, the reference materi-als IAEA-367 and IAEA-368 — marine sediments —were used.
For the analysis of alpha emitting radio-nuclides and 90Sr in food samples, two compositesamples consisting of coconut meat and the cor-responding coconut fluid were prepared from three
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coconuts (COC01, 02, 03) obtained from a samplinglocation of elevated soil activity concentration. Simi-larly, the coconut meat and corresponding fluid fromfour coconuts (COC17, 18, 19, 20) from randomlyselected locations were combined into two other com-posite samples (one meat and one fluid). Only edi-ble parts of pandanus and breadfruit were analysed.For QC purposes, the reference material IAEA-307(marine plant Posidonia oceanicd) was used.
A-3. RESULTS AND DISCUSSION
A-3.1. Measurements of the absorbeddose rate in air
The measurements of the absorbed dose ratein air at selected locations on Bikini Island areshown in Table A-I. The results range from 0.06 to0.50 fj,Gy-h~l (0.5-4.4 mGy per year) and are in goodagreement with the information presented earlier tothe Advisory Group, as given in Table XI and Fig. 3of the main report.
52
A—3.2. Preliminary determination of 137Csconcentrations in selected foodstuffsand soil samples on Bikini Island
The results obtained show the expected higherconcentrations of 137Cs in coconuts and pandanusfruits from the locations where soil was not treatedwith KC1, and considerably lower 137Cs levels in thesame fruits from locations where the soil had beentreated with KC1, shown in Table XX of the mainreport.
A—3.3. Activity concentrations ofradionuclides in soil
The concentrations of 137Cs, 241Am, 90Sr and239+240pu jn topgoji and vertical profile soil sam-ples from non-disturbed locations are given in TablesA-II and A-III. The activity concentrations of eachnuclide in topsoil (0-2 cm) at different locations showa wide variation — by more than an order of mag-nitude for 137Cs. This is consistent with previouslyreported data given in Table VI of the main report.The concentrations of 137Cs decrease with depth atall locations sampled (Table A-III), but at two of thelocations sampled, 241Am concentrations were almostconstant throughout the top 17 cm of soil.
The mean activity concentrations of 137Cs,90Sr, 239+240pu and 241 Am ^ y measured by the
IAEA were compared with those reported earlierto the Advisory Group (Table A-IV). Overall thereis good agreement between the values reported tothe Advisory Group in December 1995 and thoseobtained later by the IAEA team. Any differencescan probably be ascribed to the necessarily limitednature of the soil sampling by the IAEA team.
A—3.4. Activity concentrations in foodstuffs
Table A-V presents the activity concentra-tions of 137Cs and 40K in the edible parts of bread-fruit, pandanus and coconuts. The breadfruit samples
originate from the only place on Bikini Island wherebreadfruit is available, and the 137Cs concentrationsin the breadfruits sampled are very similar. The 137Csactivity concentration was markedly lower in the pan-danus and coconut samples collected at locationswhere the soil had been treated with KC1.
Activity concentrations per unit mass ofselected breadfruit, pandanus and coconut (compos-ite fluid and meat samples) for 90Sr and transuranicradionuclides 239+240pu anc[
241Am are shown inTable A-VI. The 90Sr activities are about one orderof magnitude lower than the respective 137Cs activ-ities in the relevant foodstuffs, and the activities of239+240pu and 241 Am are much lower than the 90gr
values.A comparison of 137Cs, 90Sr, 239+240pu and
241 Am activity concentrations in selected foodstuffswith those reported to the Advisory Group is madein Tables A-VII to A-X. Samples obtained from soillocations treated with KC1 are excluded from thiscomparison. Both the mean values and the ranges ofactivity concentrations for 137Cs, 90Sr, 239+240pu and241 Am in selected foodstuffs measured by the IAEAteam are in good agreement with previously reporteddata.
A-4. CONCLUSIONS
The IAEA monitoring mission to Bikini Islandwas of limited duration and scope but it was suffi-cient for the IAEA experts to corroborate the envi-ronmental radiation data presented to the AdvisoryGroup meeting in December 1995 and to concur withthe account of the radiological conditions on BikiniIsland contained in the main report. The measure-ments are generally in good agreement with the pre-viously reported values contained in the main report.The minor differences are not radiologically signifi-cant and can be ascribed to the limited amount ofsampling that was possible by the IAEA team.
53
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60
TABLE A-IL ACTIVITY CONCENTRATIONS IN TOPSOIL SAMPLES(0-2 cm) COLLECTED AT DIFFERENT LOCATIONS ON BIKINI ISLAND(Bq-g-1 DRY MASS); REFERENCE DATE: 20 MAY 1997
Sample code 137Cs 241Am 90.Sr 239+240pu
TOPITOPSTOP4TOPSTOP6
4.50 ± 0.092.78 ±0.081.57 ±0.040.45 ± 0.011.10 ±0.03
0.445 ± 0.0100.143 ±0.0080.191 ± 0.0070.084 ± 0.0050.069 ± 0.006
2.6 ± 20%
0.4 ± 20%
0.58 ± 20%
0.09 ± 20%
TABLE A-III. ACTIVITY CONCENTRATIONS IN SOIL CORE SAMPLES(0-2, 2-7, 7-12, 12-17, 17-27 AND 27-37 cm) COLLECTED ATDIFFERENT LOCATIONS ON BIKINI ISLAND (Bq-g-1 DRY MASS);REFERENCE DATE: 20 MAY 1997
Sample code
COR1-1COR1-2COR1-3COR1-4COR1-5COR1-6COR2-1COR2-2COR2-3COR2-4COR2-5COR2-6COR3-1COR3-2COR3-3COR3-4COR3-5COR3-6COR4-1COR4-2
137Cs
5.20 ±0.102.80 ± 0.081.61 ± 0.042.07 ± 0.060.43 ± 0.01
0.102 ±0.0047.5 ± 0.2
2.26 ± 0.061.45 ± 0.040.97 ± 0.030.76 ± 0.02
0.179 ±0.0040.386 ± 0.0080.225 ± 0.007
0.0665 ± 0.00040.0336 ± 0.00060.0155 ± 0.00070.0120 ±0.0004
2.48 ±0.051.31 ± 0.04
241 Am
0.68 ± 0.010.66 ±0.020.44 ± 0.010.65 ± 0.020.06 ± 0.02
< 0.0060.65 ± 0.020.63 ± 0.020.44 ± 0.01
0.183 ±0.0050.129 ±0.005
<0.010.018 ± 0.002
0.0083 ±0.00090.003 ±0.002
< 0.009< 0.006< 0.006
0.285 ± 0.0070.34 ±0.01
90S]. 239+240pu
2.3 ± 20% 0.89 ± 20%
2.4 ±20% 0.12 ±20%
2.4 ± 20% 0.97 ± 20%
1.8 ± 20% 0.20 ± 20%
61
TABLE A-IV. COMPARISON OF MEAN ACTIVITY CONCENTRATIONS OF 137Cs,90Sr, 239+24°pu AND 241Am (Bq-g"1 DRY MASS) IN SOIL ON BIKINI ISLAND
Soil depth (cm)
Topsoil"Previous data (0-5 cm)
IAEA (0-2 cm)
5-10 cm"Previous data (5-10 cm)
IAEA (2-7 cm)
10-15 cm"Previous data (10-15 cm)
IAEA (7-12 cm)
15-25 cm"Previous data (15-25 cm)IAEA (12-17 cm)IAEA (17-27 cm)
25-40 cm"Previous data (25-40 cm)IAEA (27-37 cm)
137Cs
3.02.1
1.81.6
1.01.0
0.481.00.40
0.190.09
90Sr
2.11.9
2.4
2.3
1.4
1.8-single value
0.77
239+240 pu
0.42
0.69
0.44
0.34
0.16
0.14-single value
0.061
241 Am
0.300.38
0.270.41
0.180.16
0.110.360.11
0.051
Previous data are taken from Table VI of the main report.
62
TABLE A-V. ACTIVITY CONCENTRATIONS IN EDIBLE PARTS OF FRUITSCOLLECTED AT DIFFERENT LOCATIONS ON BIKINI ISLAND (Bq-g-1
FRESH MASS); REFERENCE DATE: 20 MAY 1997
Sample code
BreadfruitBRE1BRE2BRE3BRE4
PandanusProm non-treated sampling areaPAN1
Prom sampling area treated with KC1PAN2
Randomly selected/from non-treated sampling areaPANS
Coconut fluidProm non-treated sampling areaCOC01COC02COC03COC04COC05COC06
Prom sampling area treated with KC1COC08COC09COC10COC11COC12COC14COC15
Randomly selected/from non-treated sampling areaCOC16COC17COC18COC19COC20
Coconut meatProm non-treated sampling areaCOC01COC02COC03COC04COC05COC06
Prom sampling area treated with KC1COC08COC09COC10COC11COC12COC14COC15
Randomly selected/from non-treated sampling areaCOC16COC17COC18COC19COC20
137Cs
0.164 ±0.0050.115 ±0.0040.175 ±0.0050.154 ± 0.005
21.4 ±0.6
1.91 ± 0.05
1.03 ± 0.03
1.88 ±0.052.41 ± 0.072.29 ± 0.062.01 ± 0.061.98 ± 0.052.22 ± 0.06
0.087 ±0.0030.084 ± 0.0030.170 ±0.0050.116 ±0.0040.146 ±0.0050.197 ±0.0060.192 ±0.007
0.43 ± 0.010.40 ± 0.010.40 ± 0.010.45 ± 0.010.41 ± 0.01
2.88 ± 0.083.60 ±0.103.20 ± 0.092.88 ± 0.083.80 ±0.103.02 ± 0.08
0.175 ±0.0060.120 ±0.0040.168 ±0.0050.148 ±0.0050.171 ±0.0060.192 ±0.0060.196 ± 0.006
0.81 ± 0.020.89 ±0.020.80 ± 0.020.83 ± 0.020.83 ± 0.02
40K
0.09 ±0.010.08 ± 0.010.10 ±0.010.09 ± 0.01
<0.3
0.06 ± 0.01
0.07 ±0.03
0.03 ±0.010.03 ± 0.010.03 ± 0.010.04 ± 0.010.03 ± 0.010.04 ±0.01
0.09 ± 0.010.07 ±0.010.11 ±0.010.11 ±0.010.09 ± 0.010.11 ±0.010.11 ±0.02
0.07 ±0.010.09 ± 0.010.07 ± 0.010.10 ±0.010.09 ± 0.01
<0.090.10 ±0.020.09 ±0.020.08 ± 0.010.05 ± 0.010.07 ± 0.01
0.15 ±0.020.15 ±0.020.14 ±0.010.14 ±0.010.17 ±0.010.12 ±0.010.13 ±0.01
0.13 ±0.010.15 ±0.010.13 ±0.010.13 ±0.020.12 ±0.01
63
TABLE A-VI. ACTIVITY CONCENTRATIONS IN EDIBLE PARTSOF FRUITS COLLECTED AT DIFFERENT LOCATIONS ON BIKINIISLAND (Bq-g-1 FRESH MASS); REFERENCE DATE: 20 MAY 1997
Sample code
BreadfruitBRE3
PandanusPAN1PAN2
Coconut fluidCOC01-COC03COC17-COC20
Coconut meatCOC01-COC03COC17-COC20
239+240pu
1
38
<4<2
<42
.1
.6
.4
.2
.0
.8
.7
X
X
X
X
X
X
X
HP7
io-4
1(T7
1(T7
io-7
1(T7
io-7
<3
15,
<3,1
<4.4,
241 Am
.7
.7
.0
.4
.1
,0.2
X
X
X
X
X
X
X
io-7
1(T5
10~7
1<T7
io-7
io-7
io-7
2.7
2.11.5
4.96.3
3.01.5
90Sr
X
X
X
X
X
X
X
io-2
10-1
io-2
io-4
io-3
io-3
io-2
TABLE A-VII. COMPARISON OF 137Cs ACTIVITIES IN FOOD(Bq-g-1 FRESH MASS)
Food type Mean Minimum Maximum
Coconut fluid"Previous
IAEAdata 1.
0..2.8
X
X
10°10°
2.88.4
X
X
io-2
1Q~&6.12.4
X
X
10°10°
Coconut meat"Previous
IAEAdata 2.
1..9.2
X'
X
10°10°
1.41.2
X
X
10-1
10-11.63.8
X
X
10+1
10°
Pandanus fruit"Previous
IAEA
Breadfruit"PreviousIAEA
data 3..98.1
data 3L
.8
.5
X
X
X
X
10°10°
10-1
w-1
1.11.0
9.01.2
X
X
X
X
10-1
10°
io-2
10~l
1.92.1
1.11.7
X
X
X
X
10+1
10+1
10°ID'1
1 Previous data are taken from Table VII of the main report
64
TABLE A-VIII. COMPARISON OF 90Sr ACTIVITIES IN FOOD(Bq-g-1 FRESH MASS)
Food type
Coconut fluid"Previous dataIAEA
Coconut meat"Previous data
IAEA
Pandanus fruit"Previous dataIAEA
Breadfruit"Previous data
IAEA
4
5
1
6,2.
Mean
.5 x 10"4
.9 x ID"3
.2 x lO"1
.9 x 1Q-2
7 x 10~2
Minimum
7.1 x4.9 x
6.3.
8.1.
6.
.3 x
.0 x
.6 x5 x
0 x
io-5
10-*
io-4
W~3
io-3
io-2
10-s
Maximum
8.86.3
21
32
2
.9
.5
.6
.1
.0
xx
xx
xx
x
io-4
10~s
10-10-
10-
2
-2
1
10-'
lo-1
single value
a Previous data are taken from Table VIII of the main report.
TABLE A-IX. COMPARISON OF 239+240pu ACTIVITIES IN FOOD(Bq-g-1 FRESH MASS)
Food type
Coconut fluid"Previous dataIAEA
Coconut meat"Previous dataIAEA
Pandanus fruit"Previous dataIAEA
Breadfruit"Previous dataIAEA
Mean
1.0 x
2.7 x
3.2 x
1.8 x1.1 xsingle
io-6
io-6
io-6
io-6
io-7
value
Minimum
3.3 x2.0 x
1.7 x<2.7 x
3.4 x8.4 x
1.4 x
w-T
10~7
io-7
io-7
io-7
10~7
io-7
Maximum
2.2 x<4-2 x
1.4 x<4.8 x
1.1 x3.6 x
9.8 x
io-6
w-7
1Q-6
w-7
ID"5
10~4
1Q-6
5 main report.
65
TABLE A-X. COMPARISON OF 241Am ACTIVITIES IN FOOD(Bq-g-1 FRESH MASS)
Food type
Coconut fluidaPrevious data
IAEA
Coconut meataPrevious data
IAEA
Pandanus fruit"Previous data
IAEA
Breadfruit"Previous data
IAEA
Mean
8.5 x 1(T6
single value
3.6 X 1(T6
3.8 x 1<T6
1.2 x 1(T6
<3.7 x 10~7
single value
Minimum
1.1 x 10~7
5.0 x 1(T7
<4.0 x 10~7
2.8 x 10-7
5.0 x 10~7
1.5 x 1(T7
Maximum
<3.4 x If)-7
1.6 x 1(T5
<4.2 x 10~7
1.5 x 10~s
1.7 x 10~s
5.3 x 10~6
a Previous data are taken from Table X of the main report.
66
CONTRIBUTORS TO DRAFTING AND REVIEW
Advisory Group members
Lokan, K.(Chairman)Bennett, B.Fry, F.Gonzalez, A.J.(Scientific Secretary)Martin, G.Matuchenko, A.McEwan, A.C.Nagaoka, T.Robison, W.L.Schmidt, R.Simon, S.L.(Consultant)
IAEA staff
Baxter, M.Danesi, P.R.Delves, D.Gnugnoli, G.Linsley, G.Mason, G.C.Stegnar, P.Webb, G.
Delegation of the Republic of theMarshall Islands
Senator H. Balos(Head of Delegation)
Bill, A.Jibas, K.U.Juda, K.Juda, L.Juda, T.Johnson, J.Note, K.Note, M.Note, N.Niedenthal, J.M.Niedenthal, R.Samuel, M.Weisgall, J.
Australian Radiation Laboratory, Australia
UNSCEAR, ViennaNational Radiological Protection Board, United KingdomInternational Atomic Energy Agency, Vienna
Commissariat a 1'energie atomique, FranceNational Commission on Radiological Protection, Russian FederationNational Radiation Laboratory, New ZealandJapan Atomic Energy Research Institute, JapanLawrence Livermore National Laboratory, USAWorld Health Organization, GenevaFormer resident scientist of the Republic of the Marshall IslandsNationwide Radiological Study
Advisory Group MeetingVienna, Austria: 11-15 December 1995
67
No. 6, February 1998
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