radiological assessments for the resettlement of rongelap in the republic of the marshall islands

title:RadiologicalAssessmentsforResettlementofRongelapintheRepublicoftheMarshallIslands

author:publisher: NationalAcademiesPress

isbn10|asin: 0309050499printisbn13: 9780309050494ebookisbn13: 9780585142555

language: English

subject

Radioactivepollution--MarshallIslands--RongelapAtoll,Radioactivefallout--Toxicology--MarshallIslands--RongelapAtoll.

publicationdate: 1994lcc: RA1231.R2N3531994ebddc: 363.17/99/099683

Radioactivepollution--MarshallIslands--

subject: RongelapAtoll,Radioactivefallout--Toxicology--MarshallIslands--RongelapAtoll.

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RadiologicalAssessmentsforResettlementofRongelapintheRepublicoftheMarshallIslands

CommitteeonRadiologicalSafetyintheMarshallIslandsBoardonRadiationEffectsResearch

CommissiononLifeSciencesNationalResearchCouncil

NatioanlAcademyPressWashington,D.C.1994

Pageii

NationalAcademyPress2101ConstitutionAvenue,N.W.,Washington,D.C.20418

TheprojectthatisthesubjectofthisreportwasapprovedbytheGoverningBoardoftheNationalResearchCouncil,whosemembersaredrawnfromthecouncilsoftheNationalAcademyofSciences,theNationalAcademyofEngineering,andtheInstituteofMedicine.Themembersofthecommitteeresponsibleforthereportwerechosenfortheirspecialcompetenciesandwithregardforappropriatebalance.

ThisreporthasbeenreviewedbyagroupotherthantheauthorsaccordingtoproceduresapprovedbyaReportReviewCommitteeconsistingofthemembersoftheNationalAcademyofSciences,theNationalAcademyofEngineering,andtheInstituteofMedicine.

ThisprojectwaspreparedunderGrantNo.DE-FG05-92EH89138betweentheNationalAcademyofSciencesandtheDepartmentofEnergy.

Cover:OceanbeachonRongelapIsland;photobyEvanDouple.

LibraryofCongressCatalogCardNo.94-65989InternationalStandardBookNumber0-309-05049-9

B-328

Additionalcopiesofthisreportareavailablefrom:

NationalAcademyPress2101ConstitutionAve.,NWBox285Washington,DC20055800-624-6242202-334-3313(intheWashingtonMetropolitanArea)

Copyright1994bytheNationalAcademyofSciences.Allrights

reserved.

PrintedintheUnitedStatesofAmerica

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CommitteeonRadiologicalSafetyintheMarshallIslands

JAMESV.NEEL(Chairman),DepartmentofHumanGenetics,UniversityofMichigan,AnnArbor

STUARTC.FINCH(ViceChairman),RobertWoodJohnsonMedicalSchool,Camden,NewJersey

BRUCEB.BOECKER,InhalationToxicologyResearchInstitute,Albuquerque,NewMexico

LAURENCEM.CARUCCI,DepartmentofSociology,MontanaStateUniversity,Bozeman

JESSEM.CLEVELAND,U.S.GeologicalSurvey(ret.),Boulder,Colorado

PHILIPM.DIXON,SavannahRiverEcologyLaboratory,Aiken,SouthCarolina

JANETL.GREGER,UniversityofWisconsin,Madison

WAYNEC.HANSON,LosAlamosScientificLaboratory(ret.),Bellingham,Washington

NEALS.NELSON,EnvironmentalProtectionAgency,Washington,D.C.

RICHARDV.OSBORNE,ChalkRiverLaboratories,Canada

CHARLESE.ROESSLER,UniversityofFlorida,Gainesville

JOSEPHC.SCHOOLAR,BaylorCollegeofMedicine,Houston,Texas

NationalResearchCouncilStaff

D.DENNISMAHLUM,StudyDirectoruntilFebruary28,1993

LARRYH.TOBUREN,StudyDirectorasofFebruary1,1993

JOHND.ZIMBRICK,DirectorasofJuly5,1993

DORISE.TAYLOR,AdministrativeAssistant

NORMANGROSSBLATT,Editor

SPONSOR'SPROJECTOFFICER

R.ThomasBell,DepartmentofEnergy

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BoardonRadiationEffectsReasearch

WARRENK.SINCLAIR(Chairman),NationalCouncilonRadiationProtection&Measurements(ret.),Bethesda,Maryland

DOUGLASGRAHN,ArgonneNationalLaboratory(ret.),Madison,Indiana

ERICJ.HALL,ColumbiaUniversity,NewYork,NewYork

MAUREENM.HENDERSON,FredHutchinsonCancerResearchCenterandUniversityofWashington,Seattle

LEONARDS.LERMAN,MassachusettsInstituteofTechnology,Cambridge

JOHNB.LITTLE,HarvardUniversity,Cambridge,Massachusetts

JONATHANM.SAMET,NewMexicoTumorRegistry,UniversityofNewMexico,Albuquerque

THOMASS.TENFORDE,BattellePacificNorthwestLaboratories,Richland,Washington

ARTHURC.UPTON,NewYorkUniversityMedicalCenter(ret.),NewYork,NewYork(untilJune30,1993)

H.RODNEYWITHERS,UCLAMedicalCenter,LosAngeles,California(effectiveJuly1,1993)


JOHND.ZIMBRICK,DirectorasofJuly5,1993

CHARLESW.EDINGTON,DirectoruntilMay17,1993

EVANB.DOUPLE,SeniorProgramOfficer

D.DENNISMAHLUM,SeniorProgramOfficeruntilFebruary28,

1993

LARRYH.TOBUREN,SeniorProgramOfficer

CATHERINES.BERKLEY,AdministrativeAssociate

MAURITADOW-MASSEY,ProjectAssistant

DORISE.TAYLOR,AdministrativeAssistant

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CommissiononLifeSciences

THOMASD.POLLARD(Chairman),JohnsHopkinsMedicalSchool,Baltimore,Maryland

BRUCEN.AMES,UniversityofCalifornia,Berkeley

JOHNC.BAILAR,III,McGillUniversity,Montreal,Canada

J.MICHAELBISHOP,UniversityofCaliforniaMedicalCenter,SanFrancisco

JOHNE.BURRIS,MarineBiologicalLaboratory,WoodsHole,Massachusetts

MICHAELT.CLEGG,UniversityofCalifornia,Riverside

GLENNA.CROSBY,WashingtonStateUniversity,Pullman

LEROYE.HOOD,UniversityofWashington,Seattle

MARIANE.KOSHLAND,UniversityofCalifornia,Berkeley

RICHARDE.LENSKI,MichiganStateUniversity,EastLansing

EMILA.PFITZER,HoffmannLaRoche,Inc.,Nutley,NewJersey

MALCOLMC.PIKE,USCSchoolofMedicine,LosAngeles,California

HENRYC.PITOT,III,UniversityofWisconsin,Madison

PAULG.RISSER,MiamiUniversity,Oxford,Ohio

JONATHANM.SAMET,NewMexicoTumorRegistry,UniversityofNewMexico,Albuquerque

HAROLDM.SCHMECK,JR.,Armonk,NewYork

CARLAJ.SHATZ,UniversityofCalifornia,Berkeley

SUSANS.TAYLOR,UniversityofCaliforniaatSanDiego,LaJolla

P.ROYVAGELOS,Merck&Co.,Inc.,WhitehouseStation,NewJersey

JOHNL.VANDEBERG,SouthwestFoundationforBiomedicalResearch,SanAntonio,Texas

TORSTENN.WIESEL,RockefellerUniversity,NewYork,NewYork


PaulGilman,ExecutiveDirector

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TheNationalAcademyofSciencesisaprivate,nonprofit,self-perpetuatingsocietyofdistinguishedscholarsengagedinscientificandengineeringresearch,dedicatedtothefurtheranceofscienceandtechnologyandtotheiruseforthegeneralwelfare.UpontheauthorityofthechartergrantedtoitbytheCongressin1863,theAcademyhasamandatethatrequiresittoadvisethefederalgovernmentonscientificandtechnicalmatters.Dr.BruceM.AlbertsispresidentoftheNationalAcademyofSciences.

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Preface

Background

TheCommitteeonRadiologicalSafetyintheMarshallIslandswasestablishedbytheNationalResearchCouncilinresponsetoarequestfromtheU.S.DepartmentofEnergy(DOE)toassistthedepartmentinevaluatingtheradiologicalsafetyoftheMarshallIslands,particularlyRongelapAtoll.Theneedforsuchanevaluationstemsfromquestionsoverthepossibilityofmeetingtheradiologicalprovisionsofthememorandumofunderstanding(MOU)betweentheRepublicoftheMarshallIslandsandtheUnitedStatesregardingtheresettlementofRongelapAtoll.TheissueofresettlementitselforiginatedinthedesireoftheMarshallesetoreturntotheatollsfromwhichtheywereevacuatedasaconsequenceofnuclear-weaponstestingbytheUnitedStatesduringthe1940sand1950s.TheNationalResearchCouncilwasaskedtoreviewthescientificstudiesundertakenbyDOE1todeterminethepotentialradiologicalhazard,ifany,topersonswhomightreturntoliveonRongelapAtoll.

AcrucialprovisionoftheMOUisthatresettlementwilloccuronlyifnopersonreturningtoRongelapandsubsistingonanative-foods-onlydietwillreceiveacalculatedannualwhole-bodyradiationdoseequivalentofmorethan100mremabovebackground.ThescopeofradiologicalstudiesneededtoassurecompliancewiththisMOUcanbefocusedsomewhatinthepresentcontextbecauseoftheradioactivedecayandnormalweatheringprocessesthathastakenplaceinthe40yearssincetheBRAVOdetonation.Atthepresenttime,theonlyisotopesthatcontributesignificantlytothedoseonRongelaparethoseofstrontium-90,cesium-137,plutonium-239,plutonium-240,andamericium-241.Ofthese,cesium-137accountsformorethan

90%oftheestimateddose,strontium-90isthesecondmostsignificantcontributionat2-5%,andthetransuranicnuclidescontributelessthat5%tothetotalestimateddose(KerchnerandRobison,1993).ThisnarrowsconsiderablytheefforttoinvestigateandmodelthepotentialdosesreceivedfromfalloutradionuclidesbythosewhomightchoosetoresettleonRongelap.

AnotherprovisionoftheMOUthatisofimportancetothepeopleofRongelapastheyconsiderresettlementisanactionlimitof17pCi/gforconcentrationsofplutoniumintheisland'ssoils.ThisactionlevelintheMOUwasbasedonaU.S.EnvironmentalProtectionAgency(EPA)actionvalueof0.2µCi/m2forprotectionofthepublicfromradionuclidesintheenvironment.TheEPAactionlevelwasdevelopedforapplicationtorecentcontamination,thusalloftheradioactivitywasconsideredtobeconcentratedwithinthetop1cmofthesoil.TheMOUactionlimitof17pCi/gwasderivedbyDOEfromthis0.2µCi/cm2EPAguideline

1Throughoutthisreport,referencestoDOEandtoworkperformedbyDOEshouldbeconsideredtoincludeactionsundertakenbyDOEanditspredecessors,includingtheAtomicEnergyCommissionandtheEnergyResearchandDevelopmentAgency.

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usingasoildensityof1.2g/cm3appropriatetoRongelapandassumingthattheradioactivitywasinthetop1cmofsoil.BecausethecontaminationonRongelaptookplacenearly40yearsagotheMOUconsidersthepotentialforsubsequentradionuclidemigrationinthesoilbyprovidingprovisionsforaveragingofthe17pCi/gradionuclideconcentrationoverthetop5cmofsoil.

Inthisreport,thecommitteerestrictsitsattentionlargelytothetechnicalaspectsoftheissuessurroundingresettlementofRongelapAtoll.Thecommitteerecognizes,however,thatmajor,andequallyimportant,social,ethnological,andpoliticalelementswillalsoinfluenceresettlementdecisionsbytheRongelappeople.Ithas,therefore,duringitsdeliberations,triedtomaintaindueconsiderationoffactorssuchasphysical,biological,logistical,cultural,andpsychologicalfactorsthatmayreasonablyapplytoormightcometobearontheresettlementoftheRongelappeopleandtheircontinuedwell-being.

ItisthedesireofallpartiesthatresettlementoccurinatimelyfashionbutwithoutsacrificingtheabilityoftheRongelappeopletopursuetheirliveswithoutanunacceptableriskfromradiation.Theproposedresettlementprogramisbilateral.Itssuccesswilldependonmutualityofpurposeandintent.Integraltotheprogrammustbeacommitmenttoinformation-sharingandtodirect,unambiguouscommunication.ThecommitteeassumesDOEwillensurethatallrelevantinformationanddocumentsinitspossessionaremadeavailabletotheRongelappeopleonrequestandthatallrecommendationsbythepresentNationalResearchCouncilcommitteewillbeforwardedtotheRepublicoftheMarshallIslandsandtotheRongelapResettlementProjectScientificPeerReviewGroup.

BecauseofthemanyreferencesmadeinthisreporttotheprovisionsoftheMOUbetweentheUnitedStatesandtheRepublicofthe

MarshallIslands,thefulltextoftheMOUisprovidedasanappendix.Itshouldbenoted,however,thatthecommitteewasnotaskedtorevieworcommentontheprovisionsoftheMOU,asthesearetheresultofinternationalnegotiations,andwilldosoonlyasiteffectsthescientificstudiesneededtoprovideassurancesthatitsprovisionscanbemet.

ChargetoTheCommittee

DOErequestedtheassistanceofaNationalResearchCouncilcommitteetohelpitdecidewhether"goodscience"wasbeingusedindeterminingtheappropriatenessofresettlementofMarshallIslandsatollsthatwereaffectedbytheatmosphericfalloutfromnuclearweaponstestedintheregionin1946-1958.TheNationalResearchCouncilappointedagroupofeminentscientiststoreviewandproviderecommendationsonradiological-healthissuesintheMarshallIslands.ThisgroupwastoreviewandcommentonthescientificandtechnicalmeritoftheprocessesandproceduresusedbytheDOEtoevaluatetheresettlementpotentialofMarshallIslandsatollsaffectedbyfalloutandbyactualdetonations.Thecommittee,establishedintheBoardonRadiationEffectsResearchoftheNationalResearchCouncil,wasaskedtoprovideadviceonthescientificvalidityofthetechnicalstudies,includingcommentonthemethodologiesofinvestigationsofvariouskinds:determinationofbodyburdensbybioassay,dosemodelingforestimatingingestionandinhalationofradioactivematerials,modelingandconfirmatoryassaysofthesoil-to-foodpathway,remedialmeasurestoreduceplantuptakeofradioactivematerials,andtheapplicationofcurrentinternationalstandardsfor

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radiationdoselimitsinthisparticularenvironment.Particularemphasiswastobeplacedontheevaluationofproceduresforenvironmentalmonitoringanddoseassessmentnecessarytodeterminethedosestopeoplewhowishedtoreturnandtoliveintheseatollareasandtoconsumelocal-onlyfoodsfromportionsofRongelapAtollandsurroundingatollsthatcansupportareturntotheirnativehabitsandwaysoflife.ThecommitteewasaskedtoreviewtheDOEprogramsandaccomplishments,comparethemwithcurrentpractices,andsuggestwhereadditionaldatamightberequiredforprudentdecision-makingastopotentialresettlement.Thecommitteeincludesnotonlyradiationscientists,butexpertsinanthropology,ecology,genetics,medicine,nutrition,psychology,andstatistics.

Specifically,thecommitteewasaskedtocarryoutthefollowingactivities:

ReviewandcommentontheapplicabilityofcurrentInternationalCommissiononRadiologicalProtection(ICRP)recommendationsonannualdoselimitsforgeneralpopulationsastheypertaintoanticipateddosecommitmentsafterresettlementinpotentiallycontaminatedareasoftheMarshallIslands.

Evaluateandcommentontheadequacyoffollowupanalyticaltechniquessuchaswhole-bodycountingtechniquesandurineassay,tomeasuretheaccumulationandeliminationofinternallydepositedradioactivematerialsinpeopleafterresettlementinpotentiallycontaminatedareas.

ReviewandevaluatemethodstoreducetheingestionandinhalationofradioactivematerialsbyinhabitantsoftheMarshallIslands,particularlypersonsthatresettleRongelapIslandandotherislandsintheRongelapAtoll.

EvaluatetheradiologicalimplicationsofproposeddietaryregimensforpersonswhoresettleRongelapAtoll,takingintoaccountbothnativeandimportedfoodstuffsandtherangeofvariationindietamongindividuals,includingpersonsofdifferentagegroupsandbothsexes.

Adviseonthelong-termhealthconsequencesofvariousremedialactionsdirectedatthephysicalenvironmentthatmightbeproposedtoimprovethehabitabilityofislandsintheRongelapAtoll.

EvaluatemetabolicanddosimetrymodelsforingestedradioactivematerialstodeterminewhicharethemostvalidforapplicationtoinhabitantsoftheMarshallIslands.

Tomakethoseassessments,thecommitteewasaskedtoreviewrecentICRPreports,technicaldocuments,andotherdatarelevanttotheenvironmentalassessmentofRongelapAtolland,totheextentnecessary,drawonreportsofexperienceinotherMarshallIslandsareas.Thecommitteewasalsoaskedtoreviewthescientificliteratureonbioassaymethodsand,byintervieworothermeans,gathertheviewsofscientistsandotherpersonsfamiliarwiththeneedsoftheMarshallese.Theoverallaimofthecommittee'sactivitieswastoreviewand

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evaluatetheproceduresthatDOEscientistsuseintechnicalassessmentsconcerningthepotentialresettlementofislandsintheRongelapAtolland,asrequired,otherMarshallIslandatollsaffectedbytheatmosphericnuclear-weaponstests.

Inmeetingitscharge,thecommitteehadaccesstoreports(bothinternalandpublished)preparedbyDOEcontractorstaffthatcoveredthewiderangeandvariedaspectsoftheradiologicalassessmentsbeingconductedintheRepublicoftheMarshallIslands(RMI).Inaddition,thecommitteemembersvisitedDOEcontractorlaboratoriestoobservetheproceduresandfacilitiesdevelopedandappliedintheirradiologicalstudies,conductednumerousdiscussionswithDOEcontractorstaffandwithotherscientistsactivelyengagedintheinvestigationofconditionsintheMarshallIslands.Finally,committeemembersvisitedtheMarshallIslandstobetterconnectthewrittenreportswithfirst-handinsightsfromacloselookatthesitesofcurrentradiologicalstudiesonBikiniandRongelapandtoobservetheconditionsontheislandsofMejattoandEbeye,wheremanyofthepreviousresidentsofRongelapnowreside.DiscussionswereconductedbothattheNationalAcademyofSciencesfacilitiesinWashington,D.C.,andonMejattowiththeleadersofthepeopleofRongelapwhowishtoresettle.ThecommitteealsowasprovidedwithdetailedinformationonthestudiesbeingconductedbytheNationwideRadiologicalStudyoftheRMIandtheRongelapResettlementProject,bothdirectedbyDr.S.L.Simon.Dr.SimonisaradiationscientistwhohasbeenemployedbytheRepublicoftheMarshallIslandstoleadtheseprojects.

Thisreportisorganizedtoreflectstudyofthecharacteristicsofthelandandpeople,elementsofenvironmentalanddosemodeling,characteristicsofpotentialremediationactivities,theapplicabilityofdoselimits,andrecommendationsforpost-resettlementmonitoring.Chapter1isanintroductorydiscussionoftheenvironmentaland

culturalfactorsthatunderliethedesiresofthepeopleofRongelaptoresettletheirislandhomes;italsoprovidesageneraldiscussionofthesourcesandmeasurementsofradiationuptothepresenttime.Chapters2-6evaluatethetechnicalactivitiesthathavebeenundertakentoassesstheradiologicalconditionsonRongelap.Chapter7addressestheapplicabilityofdoselimitsindiscussionsofresettlement.Chapter8considerstheapplicabilityofpossibleremedialactionsastheymightapplytoRongelap.Chapter9considerstheapplicabilityofcurrenttechnologytosupportthepost-resettlementenvironmentalandbiologicalmonitoringrequiredtomeettheconditionsspecifiedintheMOUthatwassignedbyrepresentativesofthepeopleofRongelap,theRepublicoftheMarshallIslands,DOE,andtheU.S.DepartmentoftheInterior.

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AcknowledgementsThecommittee'sworkwasgreatlyfacilitatedbyanumberofpeopleandorganizations.WithintheU.S.,weareprimarilygratefultoDr.WilliamRobisonoftheLawrenceLivermoreNationalLaboratoryandDrs.L.C.Sun,A.Moorthy,E.Kaplan,andC.B.MeinholdoftheBrookhavenNationalLaboratory.OntheMarshallIslandstrip,Dr.KeithBaverstockandDr.StevenSimon,DirectorNationwideRadiologicalStudy,RepublicoftheMarshallIslands,wereinstrumentaltothecommittee'sscientificactivities,andMr.KentHinerofRaytheontoitsphysicalneeds;Dr.RobisonprovidedanexcellentdescriptionofhisenvironmentalstudiesunderwayonBikini;andMr.RandyThomas,whoaccompaniedourgroupasarepresentativeoftheRongelapcommunity,wasinstrumentalindescribingtheimportanceoftheislandstotheirwayoflife.ThecommitteealsobenefitedfromnumerousdiscussionwithrepresentativesoftheMarshallIslands,bothduringtheirvisitstotheU.S.andintheMarshallIslands,includingMr.PeterOliver,UnderSecretary,MinisterofForeignAffairs,RepublicoftheMarshallIslands;SenatorJohnsayRiklon,Rongelap/UtirikAtollLocalGovernmentCouncil;MayorBillietEdmond,RongelapAtollLocalGovernmentCouncil;andothers.Thenecessarycontactswith,andbriefingsby,theDepartmentofEnergywereablyhandledbyMr.ThomasBellandDr.HarryPettengill.Dr.DouglasGrahn,liaisonwiththeBoardonRadiationEffectsResearch,contributedmateriallytoouractivities.Finally,inthepersonsofDrs.DennisMahlum,LarryToburen,EvanDouple,andMs.DorisTaylor,thecommitteeenjoyedexcellentstaffsupport.

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ContentsExecutiveSummary 1

Conclusions 3

Recommendations 6

MarshalleseTranslationofExecutiveSummary T-1

1.Introduction 9

Environment 10

Culture 13

RadiationExposureandDose 16

2.EnvironmentSamplingandAnalysis 21

SamplingTechniques 21

SoilSampling 22

Foodstuff 26

Conclusions 36

AnalyticalTechniques 36

Conclusions 38

3.DietaryModels 41

UjelangDietModel 41

BNLDietModelfortheNorthernMarshallIslands 46

ExtrapolationfromDietModels 49

Recommendations 50

4.MeasurementsonHumans 53

Whole-bodyCounting 54

Recommendations 56

UrinalysisforPlutonium 57

SensitivityRequirements 57

ReviewofActivities 59

Conclusionsandrecommendations 61

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5.DosimetryanditsApplication 63

DosimetryApproaches 64

Externaldose 64

Internaldose 65

IntakebyInhalationandIngestion 65

Intakethroughtheskin 65

AppraisalofCurrentDOEAssessments 66

ExternalDose 67

IntakeandInternalDose 68

Inhalation 68

Ingestion 69

Intakethroughskin 74

6.UncertaintyandVariableinDoseProjection 75

LLNLProbabilisticApproach 75

ScenarioApproach 79

Conclusions 80

7.DoseLimitsandTheirApplications 81

8.RecommendationsforRemedialActions 83

9.RecommendationsforPost-ResettlementProjection 85

RadiationDosimetry 85

MedicalConsiderations 86

References 89

Glossary 95

Appendix 97

ExecutiveSummaryTheCommitteeonRadiologicalSafetyintheMarshallIslandswasestablishedbytheNationalResearchCouncilinresponsetoarequestfromtheU.S.DepartmentofEnergy(DOE)toassistthedepartmentinevaluatingradiologicalconditionsoncertainatollsintheRepublicoftheMarshallIslands,especiallyRongelapAtoll.Theneedstemsfromtheprovisionsofamemorandumofunderstanding(MOU)establishedbetweentheRepublicoftheMarshallIslandsandtheUnitedStatesin1992.ThatagreementsetsoutcriteriaandstipulationspertainingtotheresettlementofRongelapAtoll.TheissueofresettlementitselforiginatedinthedesireforthepeopleoftheMarshallIslandstoreturntotheatollsfromwhichtheywereevacuatedasaconsequenceofnuclear-weaponstestingbytheUnitedStatesduringthe1940sand1950s.TheNationalResearchCouncilwasaskedtoreviewthescientificstudiesundertakenbytheU.S.DepartmentofEnergytodetermineifreliableandmodemscientificmethodologywasbeingusedtoassessthepotentialhazard,ifany,topersonswhomightreturntoliveonRongelapAtoll.AcrucialprovisionoftheMOUisthatresettlementwilloccuronlyifnopersonreturningtoRongelapandsubsistingonanative-foods-onlydietwillreceiveacalculatedannualwhole-bodyradiationdoseequivalentofmorethan100mremabovebackground.TheMOUalsopresentsanactionlevelof17pCi/gfortheconcentrationoftransuraniccontamination,i.e.,plutoniumandamericium,insoilsbelowwhichmitigationwillbeconsideredunnecessary.

TheassessmentoftheradiologicalconditionsonRongelapresultingfromtheU.S.testingprogramisnarrowedsomewhatbytheweatheringprocessesandnuclear-decaythathastranspiredduringthe40yearssincetheatollwascontaminated.Atthepresenttime,the

isotopesthatwouldcontributesignificantlytothedosetoindividualswhomightresideonRongelaparethoseofstrontium-90,cesium-137,plutonium-239,plutonium-240,andamericium-241.Ofthese,cesium-137accountsformorethan90%oftheestimateddose,strontium-90providesthesecondmostsignificantcontributionat2-5%,andthetransuranicnuclidescontributelessthat5%tothetotalestimateddose.

ResettlementofthenorthernMarshallIslandsisaprecedent-settingactivity.Asfarasthiscommitteeisaware,thecurrenteffortstoresettletheMarshalleseareamongthefirstinwhichagovernmenthasundertakentofacilitateandmonitorthereturnofapopulationthatwasdisplacedbecauseofconcernsforradiationexposure.Theutilityofthecriteriaandproceduresusedandtheresultingprotocolmightextendwellbeyondthepresentsituation.ThepeopleofRongelapresettledtheirhomelandin1957onlytoleaveagainin1985''onthebeliefthatRongelapwasunsafeandthatDOEhadnottoldthetruthaboutradiationeitherwithrespecttoitscontaminationofthelandsandenvironmentofRongelapAtoll,orastoitsimpact

uponthepeople.''1ItisimportantthatthecurrentefforttoassesstheradiologicalconditionsandtheirpotentialimpactsonthepeopleofRongelapavoidtheproblemsofthepast.

Initschargetothecommittee,DOEdirectedthecommitteetoreviewandcommentonthescientificandtechnicalmeritoftheprocessesandproceduresusedbyDOEanditscontractorsinitsevaluationoftheradiologicalconditionsonRongelapand,inshort,todeterminewhetheritsassessmentsmeetthestandardsofgoodscience.Thecommitteewasaskedtogiveattentionspecificallytoseveralsubjects,including:theappropriatenessofapplicationoftheInternationalCommissiononRadiologicalProtection's(ICRP)annualradiationdoselimitstothedosecommitmentsexpectedtofollowresettlement;theapplicabilityofmetabolicanddosimetrymodelsforingestedradioactivematerials;theimplicationsofproposeddietaryregimensforcalculateddoseprojections;theeffectofvariationsinthenative-to-importedfoodratioanddifferencesindietduetosex,age,orindividualpreference;themethodsproposedtoreduceexposuretoradioactivematerialsbyinhalationoringestion;theadequacyoffollow-upanalyticaltechniques;andthelong-termconsequencestohealthofproposedremediationoftheenvironment.

Inmeetingitscharge,thecommitteehadaccesstoreports(bothinternal,manyindraftform,andpublished)preparedbyDOEcontractorstaffthatcoveredthewiderangeandvariedaspectsoftheradiologicalassessmentsbeingconductedintheMarshallIslands.Inaddition,thecommitteemembersvisitedDOEcontractorlaboratoriestoobservetheproceduresandfacilitiesdevelopedandappliedinstudiesoftheradiologicalconditionsintheMarshallIslands,conductednumerousdiscussionswithDOEcontractorstaffandwithotherscientistsactivelyinvestigatingtheconditionsintheMarshallIslands,andtraveledtotheMarshallIslandsforacloselookatthesitesofcurrentradiologicalstudiesonBikiniandRongelapandto

observetheconditionsontheislandsofMejattoandEbeye,wheremanyofthepreviousresidentsofRongelapnowreside.DiscussionswereconductedattheNationalAcademyofSciencesfacilitiesinWashington,D.C.,andonMejattowiththeleadersofthepeopleofRongelapwhowishtoresettle.ThecommitteealsowasprovidedwithdetailedinformationonthestudiesbeingconductedbytheNationwideRadiologicalStudyandtheRongelapResettlementProject,bothofwhichareunderthedirectionofDr.S.L.Simon,ahealthphysicistemployedbytheRepublicoftheMarshallIslands.

ThecommitteeconductedacomperhensivereviewandevaluationofthedataavailabletoitregardingtheinvestigativeproceduresandmodelsusedintheassessmentofthepotentialdosesthatmightbeincurredbythoseindividualswhochoosetoreturnandliveonRongelap.Inmanyinstancesthecommitteehadtorelyondiscussionswiththeinvestigators,andunpublishedproceduresandresultsprovidedininternalreportsinitsinvestigation;itseemsnottohavebeenthetraditionoftheseDOEprogramstopublishextensivelyinthepeerreviewedliterature.Basedonitsexperiences,thecommitteewouldrecommendthatinthefuturetheDepartmentofEnergyplacegreateremphasisonpublishingresultsobtainedinitsprogramsinthepeer-reviewedliterature.

1QuotedfromthetestimonyofSenatorJetonAnjain,MarshallIslands,onbehalfofthepeopleofRongelap,beforetheHouseCommitteeonAppropriations,SubcommitteeonInteriorandRelatedAgencies,TheHonorableSidneyR.Yates,Chairman,May9,1991.

TheMOUthatwasnegotiatedbetweenthegovernmentsoftheUnitedStatesandtheRepublicoftheMarshallIslandsincludesaratherunusualrequirementinitspresentationofaradiationdoselimitintermsofthedosetothemaximallyexposedresident.Ingeneral,thetechniquesofradiationdosimetryarenotdevelopedfordeterminationofdosetothemaximallyexposedindividual;itisparticularlydifficultforapopulationoflimitedsizewherethestatisticalpowerfordeterminingdosesattheextremesofdosedistributionsislimited.Inaddition,thispopulationhasthepotentialtogatherfoodfromotherislandsthatmayhavehigherradiationburdens,andindividualsmay"binge"onfoodsofhigherthanaverageradionuclideconcentration,e.g.,coconutcrab.Thesepossibilitiesmakeestimatesofthedosetothemaximallyexposedresidenthighlyuncertain.ThecommitteewouldpreferthattheMOUconformtomorecommonradiationprotectionpracticesinstatingdoselimits,howeveritwasnotwithinthechargetothecommitteetoimplementorrecommendchangestotheMOU;theseprovisionsstemfromapreviouslynegotiatedinternationalagreement.Therefore,assessmentofdoseestimatesandapplicationofdosemodelingmustbeconsideredwithinthecontextoftheprovisionsoftheMOU.Althoughtheavailabledataandthestandardproceduresinradiationprotectiondonotlendthemselvestoanaccurateevaluationofthedosetothemaximallyexposedresident,thecommitteepresentsanassessmentoftheuseofstatistics,andofscenarios,inthereportinanattempttoaddressthisissue.

Conclusions

Thefollowingsummarizesthecommittee'sconclusionsbasedonitsreviewofallthematerialacquiredduringthecourseofitsdeliberationsconcerningthepointsenumeratedinthecommittee'scharge.

1.ApplicabilityofICRPrecommendationsonannualdoselimits.The

committeewasaskedtocommentontheICRPrecommendationsforgeneralpopulationsasrelatedtotheresettlementofRongelapandotherMarshallIslandspopulations.BecausetheICRPrecommendationswerenotdevelopedwiththepresentsituationinmindandannualdoselimitshavealreadybeennegotiatedfortheresettlementofRongelapandformalizedintheMOU,thecommitteedidnotfeelthatitwouldserveausefulpurposetoundertakeadetaileddiscussionofexposurestandards.AlthoughtheICRPdoselimitsapplicabletothepublicwerenotdesignedforapplicationtoresettlementofpreviouslycontaminatedland,theICRPrecognizestheuseofnumericalcriteria,actionlevelsasdefinedintheMOU,asusefultoolsindecisionmaking.ThisissueisdiscussedinChapter7.

2.Environmentalsamplingandanalysis.Theprogramsforsystematicenvironmentalsamplingandradioassayofsoil,vegetation,water,andfoodstuffsonRongelaphavebeenbroadinscopeandofveryhighquality.Themajorfocusofthesestudieshasbeenontheconcentrationsofcesiuminthesoil,breadfruit,coconuts,andpandanusandtheconcentrationsoftransuranicelementsinthesoilastheprimaryradionuclidesofinterestinthisenvironment.TherigidapplicationofreliablelaboratorytechniquesbythescientistsoftheLawrenceLivermoreNationalLaboratory(LLNL),aDOElaboratory,hasprovidedasubstantial

backgroundofinformationusefulintheestimationofpotentialradiationdosestotheresettlementpopulationfromexposuretoradiationintheenvironmentorthroughingestion.

3."HotSpots".ThepotentialforradionuclidehotspotsinunsampledregionsoftheislandhasbeenofnotableconcerntotheRongelapcommunity.However,giventherelativelyuniformdistributionofradionuclidesobservedintheLLNLgridusedtosamplesoilforradioactivityonRongelapandthenatureofthesourcecontamination,thecommitteeseeslittlereasontosuspecttheexistenceoflocalizedhighconcentrationsofradionuclides(plutonium,cesium,etc.)thatwouldcontributeto"hotspots."(Thecommitteehasacceptedthedefinitionofa"hotspot''asalocalregioninwhichtheradionuclideconcentrationhasavalueof10ormoretimesthemeanofthepresentobservations.)

4.Dietarymodels.TheinformationobtainedfromanumberofdietarysurveysdoesnotappearadequatetoprovideareasonableestimateofeithercurrentorindigenousdietsfortheRongelapcommunity.Basedontheavailableinformation,however,thecommitteeestimatesthatasizeablefractionofthepersonsonapurelynativediet,oranyotherdietthatincludesalargeintakeofcoconuts,couldexceedthe100-mrem,abovenormalbackground,annualdoseequivalentlimitspecifiedintheMOU.Theeffectsoftheseuncertaintiesinthedietmodelsarealsodiscussedinconclusions6and7below.

5.Measurementsonhumans.Thewhole-bodycountingsystemcurrentlyusedintheMarshallIslandsbyDOEcontractorstaffoftheBrookhavenNationalLaboratory(BNL)ispracticalandreliableformeasuringcesium-137bodyburdens.TomonitortheRongelappopulationadequatelyforwhole-bodyburdens,sothatsufficientlyaccurateinformationisobtainedtoassurecompliancewiththeMOU,itwillbenecessarytofollowindividualsintheresettlement

populationsystematicallyforanindefiniteperiodoftime.IntheenvironmentofRongelap,strontium-90,plutonium-239,andplutonium-240areexpectedtomakeonlyaveryminorcontributiontodosesreceivedfromthelong-termexposure.Theaccuratemeasurementofplutonium-239andplutonium-240intheurineattheexpectedvery-lowlevelsisextremelydifficult,ifpossible,usingcurrenttechniques.Theproblemsinaccuratelymeasuringandinterpretingconcentrationsofplutoniuminurineneedtobeaddressed,improvementsdocumented,andpracticalconsiderationsandlimitationsunderstoodinanyprogramthatmightbesetuptomonitorplutoniumintake.

6.Dosimetryanditsapplication.DoseestimateshavebeenmadebyDOEcontractorpersonnelinaccordancewithacceptedmethodsputforthbytheICRP.External-doseestimatesareaccurateandsufficientlycomprehensive.Internaldoseestimatesthoserelatedtodosesreceivedthroughinhalation,ingestion,andabsorptionarelesscompletebecauseage-specificestimatesareabsent.Thisisnotaseriousdeficiencywithinthecontextofthepresentsituation,becauseestimatesforcumulativedosebasedonthe"referenceadult"tendtobeconservative.Inaddition,uncertaintiesintroducedbydosimetrictechniquesare,ingeneral,smallrelativetothoserelatedtodietaryinformationandindividualvariability.

7.Uncertaintyindoseprojections.Twogenerallyacceptedmethodsareusedtoestimatedosestothemaximallyexposedindividual.Oneistheprobabilisticapproachthatusesthemeansandvariancesoftheradiologicalcomponentsusedinmodeling.Theotheristhescenarioapproach,whichspecifiescharacteristicsofsomemaximallyexposedresident,suchasage,sex,residence,anddiet.TheLLNLdoseprojectionsprincipallyusedasophisticatedprobabilisticapproach,buttheirvalidityislimitedbythesmallnumberofsamplesavailableforestimatingdistributionsofdietaryradionuclideintakeandretention.Onthebasisofusingascenarioapproach,thepresentcommitteeestimatesthattheaverageindividualconsumingalocal-foods-onlydietcouldreceiveanannualdoseof92-106mrem/y,dependingonthechoiceofdiet;thisestimatedrangeisbasedonwhatthecommitteefeelsisthemostlikelycombinationoflocalfoodsandenergyintake(seeChapter5,Table5-4).Uncertaintyinthedoseestimateforaparticularscenariodependsontheuncertaintyinenvironmentalsamplingdataanduncertaintyinthedosimetry.Uncertaintyintheprobabilisticapproachalsodependsonthosesourcesofuncertainty,aswellasuncertaintyinthedietaryintakeandinotherindividualcharacteristics.

8.Healtheffectsofremedialactions.Thecommitteebelievesthatthemajorenvironmentalremedialactionnowunderconsideration,theuseofpotassiumfertilizer,wouldnotadverselyaffectthehealthofthoseresidingonRongelapandinfact,totheextentthatitincreasedcultivaryields,wouldimprovethenutritionofthepopulation.PotassiumchlorideisafertilizercommonlyusedintheUnitedStateswithnoknownacuteorchronichealthhazardswhenusedforthispurpose.Asecond,morelocalremedialaction,clearingcontaminatedsoilfromthevillagearea,wouldlikewiseposenoadversehealtheffects.TheCommitteefeltthatstrippingtheislandoftheorganicsoiltoremovecontaminationintheupperportionsofthesoilwould,

however,beunwiseowingtothefragileecologyoftheislandandthelongtimerequiredforregenerationoftheorganictopsoil.

Basedonthecommittee'sreviewofthescientificdata,thepotentialradiationdosesfromthedifferentsourcesofexposurethatmightaccruetothosewhochoosetoreturntoliveonRongelaparesummarizedinTable1.Herewepresentdosecontributionsfromtwooftheseveralpossibledietscenariosthatwerediscussedinthetext,namelythoseprovidedbythelocal-plus-imported-availablediet(scenarioA)presentedbyRobisonetal.(1993),andthelocal-foods-onlydietofRobisonetal.(1993),butwiththecaloricintakeadjustedtoreflectwhatthecommitteefeelsisamoreappropriateenergyintakeforanactivepopulation,i.e.,thesamecalorieintakeasobtainedforthelocal-plus-imported-foodsdiet(scenarioC).

Table1.SummaryofprojectedAverageRadiationExposurestoRongelapResidents

ContributionstoDose mSv/y (mrem/y)

I. NATURALBACKGROUNDRADIATION

A.ExternalExposurea 0.22 (22)

B.InternalRadionuclidesb 2.0 (200)

Subtotal 2.22 (222)

II. ATTRIBUTABLETOFALLOUTc ScenarioAd ScenarioCe

A.Externalexposure 0.11 (11) 0.11 (11)

B.InternalExposure

1.Ingestion 0.17 (17) 0.95 (95)

2.Inhalation 0.0043 (0.43) 0.0043 (0.43)

0.29 (29) 1.06 (106)

TOTAL:NATURALANDFALLOUT2.51 (251) 3.28 (328)

aPrimarilycosmicradiation;externalbackgroundradiationfromnaturalterrestrialsourcesisverylowinthenorthernMarshallIslands(Robisonetal.,1993)

bFromnaturally-occurringradionuclides,suchaspotassium-40,polonium-210,andlead-210inadiethighinfishcontent(Robisonetal.,1993).

cProjectedfor1995.

dScenarioAisbasedonadietthatincludestheavailabilityofimportedfoods;thisdiet,fromtheworkofRobisonetal.,(1993),containsacaloricintakeof3208/d.

eScenarioCiscomposedofthelocal-foods-onlydietdescribedbyRobisonetal.(1993),butadjustedbythecommitteetocontainthesamecaloricintakeasscenarioA.

Recommendations

Onthebasisofitsreview,thecommitteeoffersthefollowingrecommendations.

1.Becauseofthesubstantialuncertaintiesinthiscomplexandunprecedentedsituation,thecommitteerecommendsthatnocategoricalassurancesbegivenconcerningtheMOUrequirementthatnoindividualreceiveacalculatedannualradiationdoseequivalentofmorethan100mremabovebackground.SomepeoplereturningtoRongelapandsubsistingonalocal-food-onlydietmightreceiveanannualdoseinexcessof100mremabovebackgroundifthereisnoremedialaction.

2.IfthecitizensofRongelapdecidetoaccepttheuncertaintiesindoseestimatesandreturntoRongelap,theCommitteeendorsestwo,possiblytemporary,remedialactions:

Theimmediateand,asappropriate,continuingapplicationofpotassiumchlorideasafertilizertodecreaseuptakeofcesiuminfoodswherevertherearecoconutpalmsorpandanus

treesontheisland.

Onresettlement,acceptanceofaninitialdietinwhichabouthalfthecaloriesarederivedfromnon-nativefoods(whichmightbenecessaryinanycasetosupportthepopulationwhileitattemptstore-establishtheisland'seconomy).

TheseremedialactionscanberegardedastemporarymeasuresinthesensethatbothmightberelaxedifmonitoringresultsinappropriateassurancethatthedoselimitsnegotiatedintheMOUcanbemet.

3.ToprovidereassurancetothepeopleofRongelapthatthelimitsoftheMOUarebeingmet,thecommitteerecommendsthat,untilexperiencedictatesotherwise,everymemberoftheresettledcommunityreceiveawhole-bodycountforradionuclideburdenandprovideaurinesamplesufficientforanalysisforplutoniumbeforeresettlementandeachyearthereafter.Inaddition,acohortofapproximately80persons(assumingatotalresettlementpopulationofapproximately400people)stratifiedbyageandsexshouldbeexaminedfourtimesayearinthesamefashiontoestablishseasonalfluctuations,whichmustbeunderstoodifannualdosestothemostheavilyexposedaretobecalculated.

4.Thecommitteerecommendsthatattheoutset,tomeetthetermsoftheMOU,thenorthernislandsofRongelapandRongerikAtollsbeconsidered"offlimits"forfood-gathering.Thisconstraintmayberelaxediftheexperienceofthefirstseveralyearsindicatesthatthe100-mremstandardwouldbemeteveniffood-gatheringwereextendedtothenorthernislands.TheenvironmentalsamplingprogramconductedonRongelaphasprovidedanappropriatebackgroundofinformationforestimatingthepotentialdosesfortheresettlementofRongelapIsland.Thecommitteerecommendsthatacontinuedeffortbemadetocharacterizetheotherislandsintheatollthatmaybeusedforfoodgatheringinthefuture.Thisdataisneeded

toprovidedetailedestimatesofdosesthatmayoccurasaconsequenceofsuchactivities.Sucharesearcheffortshouldbecarefullydesignedwithgoalsestablishedinconcertwiththeneedsofthepeopleoftheregionandinconsultationwithexpertsinenvironmentalmonitoringanddoseassessment.Inaddition,thecommitteerecommendsthatenvironmentalmonitoringofediblefruitsbecontinuedwithafocusondeterminingthebiologicalretentionofradionuclidesintheenvironment.

5.Thecommitteerecommendsthatmedicalservices,withcomprehensivemedical-recordmaintenance,beinitiatedtopermitcontinuingevaluationofthehealthstatusofthereturningpopulation.Thisrecommendationisnotinanticipationofradiogenicillnessamongthosepersons,butratherisintendedtomeettheneedforfactualinformationifthecommunitybecomesconcernedaboutradiogenicconsequences.

6.Thecommitteerecommendsthatamoreformalcoordinationoftheradiological-assessmentactivitiesofBNLandLLNLbeestablishedthanhasexistedinthepast.Similarly,theseactivitiesshouldbecoordinatedwiththoseoftheScientificManagementTeamoftheNationwideRadiologicalStudyoftheRMI.

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PrecisoftheExecutiveSummaryIloKajinMajol**CommitteeeoikijienbobraenaninmijkorejwalokjenbaijininbombiloMajolearejakjenNationalResearchCouncileonanuwakekajitokeojenDepartmenteoanEnergyiloU.S.nanlaleimekatakkakejonanjorankoilojetianenekoiloMajol,elaptatakonRongelap.JuonkarokakkwooneoearejakikotanKieneoanAmericaimKieneoanMajolilo1992eofarnaetanMOU.KwooninearkalikarjetkajitokkoikijienannajjeblakarmijimjokweionRongelap.LemnakinearejakjenkonaneoikijienbarkejeblakarmijnanenekofarkomakiterjeniiloieneoUnitedStatesearkokomelmelekeintarinaekorekajurjen1940snan1950s.RatkajitokbweNationalResearchCouncileoenetaliekatakkoanscientistroiumuntelimlolorjakeeojenU.S.DepartmenteoanEnergynanlaleelaneekatakkeinremaronkwalokjonankauatata,neewor,nanrorenajbarrolnanRongelapimmonawotjenkeinikkankoie,imbokjonanbaijinnanenbwinierlaplokjen100mremiuminjuoniio.MOUeoejbarkomeleleikworanin17pCi/gjonanbaijenintransuraniceoilobwidrej(i.e.,plutoniumimamericium),edikjenjonaneoscientistrorejaikuijbarlomnokkakeim,bwelen,barkareo.

JonanbaijineoiloRongelapitokwotjenkokomelmelkoanU.S.emojandriklokjenukoktakinmejatotoimmotlokimbaijiniuminiiokein40.Ilotorein,baijinkonankajojororenajjokweionRongelapnajworaninstrontium-90,cesium-137,plutonium-239,plutonium-240,imamericium-241.Ibbenkeinelaplokjen90%ejcesium-137,strontium-90ejkwalok2-5%inbaijinko,imtransuranic-nuclidesrejkwalokedriklokjen5%iloaerantonelok.

JeblakimjokweiloaelonkoittueaniloMajolejkwalokelonmokitkitkorokaelri-scientistrorejaikuijlomnokkake.Committeeinejtomakkekateinclapilotoreinnankojeblaklokarmijreinnan

ijokojikierejjuoniankotebarkorellapimKieneoejbokkunanieimlalejeblaklokeoanelonarmijto,rofaremakitjenwotkauatatakoikijienradiation.Jerbalkeinikijienkomanmanlokenekoimkajeblakarmijronanijokojikieremaronjipanarmijroilololinkojetelanneebarwalokjonankauatatajenradiationtokelik.ArmijinRongelapfarjeblakilo1957imbaremakitilo1985,iloaertomakkeRongelapejjabjuonjikineoemonnanjokweie,imDOEearjabkwaloktooleokinjonanjoraninbaijineoiloenekoimmejatotoeo,imjonaneoenajjeletarmijto.EjjuonmeneoearuoknanjonwejonanlapinradiationeoimjoraneoemaronjeletarmijinRongelapimbareinwotkwalokaoleblomnokkoilomolbwetenjabpokiloaerkononoikijienjabdewotmokitkitiloaelonkoittueantokelik.

**CommitteeinearpikotjuonkilinbweinukokExecutiveSummaryinnankajinMajol.RiutiejroiloRMIEmbassy,Washington,D.C.,rarjipanlokimpikotjuonriukok.Botab,aolebrijipanfarjerbalilomokaj;kinanoktakkajinMajolimkajinbelle,imkinanbenelonwawenkononoanri-scientistro,ebonlukunjejjetaolebnankoiloukokeoilal.

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Konmaroneoan,DOEeartelcommitteeinbweenetalelokanjerbalinekatakkoanscientistronanlalejonanbaijineoiloRongelapilokakadruiklok,nanetaleelaneekatakkeinretobarjonaneoejemonwot.Rarkajitoklokibbencommitteeinbweenlukkunlalejetianuninkononoko,ibbenlokjonaneoraretalejenInternationalCommissionikkijienRadiologicalProtection(ICRP)nanlalejonanradiationeobokiuminjuoniioimlaleejimwakeaerantonelokjonanradiationeorenajbokiloaerbarjeblaknaneneko;kwalokjonanemonakenanailowawenkorejkojerbalinanjonwelokimantonelokbaijiniloanbwinienarmijimilomelanko;tokjenmonakokijierimworaneorejantonjeni;oktakkoikotankeinikkankojenmonakobuktokjenijokojet,imoktakinikkijienkorakeakemmanke,iioeoam,aktakoeitoklimoemkaki;kilenkadriklokambokradiationjenamemenonoakkilenammona;imjuonmeneoenajtojetnakinnanejmour.

Nanjibadbadlokeddoinion,committeeinearworanmaroninkwalokjerbalkoanri-jerbalroanDOErarekatakkakiimjeboleelonjikinkoimtakorenajwalokjenjoraninbaijinkorarekatakkakiiloMajolin.Ibbenlokwot,rouwancommitteeinrarlolokjikinjerbalkoanri-jerbalroanDOEnanlalewawenimkilenaeretalejoraninbaijinkoiloMajol,rarbareinwotkajitokelonkajitokkoibbenri-jerbalroanDOEimibbenscientistrorejetalewotjonanjoraneoiloMajol,imetalnanMajolbwerenlukkunlojonanjoraneoimrejekatakwotkakiiloBikiniimRongelap,bareinwotnanaeretalewawenbedionMejatoimEbeye,ijokoelonianri-Rongelaprorejjukjukimamnakierainin.KononokorarkommaniloNationalAcademyofScienceiloWashington,D.C.,imiloMejatoibbenri-telrojenRongelaproimrekonanjeblaknanRongelap.CommitteeeoeartibrikiaolepenekatakkorarkommanijenjuonekatakeorejnaetanNationwideRadiologicalStudyimRongelapResettlementProject,iumintelimlolorjakejanDr.S.L.Simon,juonphysicistin

ejmoureoimkieneoanMajolearkojerbale.

CommitteeinearwatwatelokaolebmelelekoikijienwawenjonwelokimantonelokpaijiniloaenkotueaniloMajolimbareinwotjonaneoarmijreinrenajbok,iloaerjeblaknanRongelap.Iloelonwawenko,committeeinearloriuwakkoibbenri-etalero,bareinwotkilenimwawenkorarjabkalikarilokmoktailoetalekein;ejjabjuonimineneeoDOEakinkarokbweenkwalokaolepenlokanjerbalinetalekoan.Jenmeneorarekatakjene,committeeinenajkarokbwetokalikDepartmenteoanEnergyenajlaplokanlalebwelokanetalekorekanuijinmelele.

KwooneoearkommanikotanKieneoanAmericaimKieneoanMajolnaetanMOUearkobaiklokwotjuonkotobareoeinjuonnanjonejonaneoelaptatajuonarmijemaronbokiloanbwinienikijienradiation.Jerbalinetalekoikkijienradiationrarkalikaribweinkwalokjonanyeolablabjuonbwijinarmijremaronbok;rejaninalikarakejaknankwalokjonaneoelaptataimkajojoarmijrenajbokjeni;ebareinwotlukkunbennanjonwekonjonanietinarmijreinnanjonankajurinbaijenkein.Ibbenlokwot,armijreinrarmaronkarkommanmonajenenekojetelaplokradiationkoie,imkajojoarmijremaronkarmonajenmonakoelaplokanbaijininbedie,einwotbarulep.Aoleblemnakkeinrekommananbennanantonelokjonaneoelaptattajuonwotarmijeoenajbokilojuonmelaneo.CommitteeinearkonanbweMOUeoenkalikarelonlokkeinkaminenekonanbobraeradiationrejbuki,botapejelokancommitteeinmaronnankommanoktakiloMOUeo;aolepenantonekeinraikuijwonmanlokwotjenkarokeotokjenMOUeo.Botapaolepjerbalinetalekeinikijienbobraeradiationrejjabjimwenanarmijrorenajbokijenjonanlapinbaijineo,committeeinear

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kwalokwanjonakkobwerenmaronwonmanlokwotimworaermeninkononokakeabnonoin.

Jemlokko

Committeeinearkommanjemlokkeinjenaolepenkakobabakorarlemnakkake.Aolebmelelekoreaorektattarejbedilal.

1.WarenkojerbalikarokkojenICRPiloaeloninMajol.RarkajitoklokibbencommitteeinbweenkwaloklemnakeoanikijienkarokkojenICRPilojeblakimroleoanarmijronanRongelap,imbareinwotrojetibelakinMajol.KonkekarokkojenICRPrarjabkalikariekkarnanmokitkitrotin,committeeeoearejakkeejjabmaronlorekarokkojenICRP.Bareinwot,nanrorenajjeblakimbedionRongelapimejkalikarjonanbaijeneoelaptattajuonarmijemaronbokiiloMOUeo,eninuninankarcommitteeinjabbarlemnakkeenajjipanlokimtibdrikijonaneoemojkajetjete.Botap,ekkareojenICRPnanjonwejonanbaijineonanaoleparmijrarjabkommanikijienrorenajjeblaknanenekoemojaerjoranjenbaijininbombko,ICRPearkilebwinbwininkakilenkoelajrakimkalikariloMOUeoeinwotjuonmeneoeauroknankenankake.Meninkononoinejkomeleleiklokilojebta7.

2.Tibdrikinimjonakinmelanko.Lajrakinjonakkoilomelanjenbwidrej,keinikkanko,drenimmonakoionRongelapelapanmulalimtiljokaerjerbale.Aolebjerbalkeinrarkajionimetalejoninlapincesiumeoilobwidrej,ma,waini,imbobkoimjonantransuraniceoilobwidrej,katakkeinikijienradiationrekijonwalokilomelankein.JerbalinkajimwekeinimrarkommanjenscientistroiloLawrenceLivermoreNationalLaboratory,juonjikinetaleanDOE,earkalikardebdebinmelelekonanantonelokjonanradiationeonajbokjenmejatotoeokabmonakoiloaernajrolimbediloeneko.

3."Jikindrikdrikkoelapbaijenie."Jikindrikdrikkoremaronlukuun

joraniloijokorejaninkakileniejjuonanri-Rongelapabnono.Ijowotke,jonenanlonjikinkoraretaleiloaeneo,committeeinejjabtamakenajworjikindrikdrikkoelekunlabbaijenie.Bareinwot,konkeenaninjonanwotjuonradiationiloijokoraretalijenLLNL,imkinwawenanbaijenwalokjenbombeo,committeeinejjablouninanekkolkonjonanlabinradiation(plutonium,cesium,imbaijenkojet)koremaronkwalokbweenwor"jikindrikdrikkoelapbaijenie."(Committeeinearbokkomelelein''jikindrikdrikkoelapbaijenie"einwotjuonjikinjonankajurinradiationeoej10alenlaplokjenjikinkojetemojaerekatakkakekio.)

4.Jonakkoilomonako.Melelekobokjenelonjerbalinetalekokonmonako,rejjabjejjetiloaerantonelokjonaneori-Rongelaproremaronbokjenmona.Bedbedionmelelekein,ijokecommitteeinearwatwatelokkeenaninaolepenrorejmonajenkeinikkanko,akmonakoitokjenniimwaini,maroninlaplokjen100-mrem,akkonlokjenjonaneoemojaerkajejjetiuminjuoniioeoemojkelajrakeiloMOUeo.Tokjenaerjablukunjelakakejonanarmijkajojorenajmonaim,kinmenin,jonanbaijenie,rejbarkomeleleikilokomelelekoilalilo6im7.

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5.Jonakimkakelkelkoiloarmij.BwinbwininjuonenbwininarmijkorejkommaniloMajoljenrijerbalroanDOEiloBrookhavenNationalLaboratory(BNL)ejkwalokjonanjorankoiloenbwinier,bwetenmaroninerreekkarnankarokeoiloMOUeo,emeninaikuijbwetenekatakkakekajojoarmijiloaernajjeblakimbweenjabjemlokjerbalinetalekonanermaejuonienettojenrankein.MelanimmejatotoeoiloRongelap,strontium-90,plutonium-239,implutonium-240rejkotmenekeenajkwalokjidrikinwotjonaneobokejenantoanenbwinnimajorwawananbaijinin.Jonandrikinbaijenen,jejetinjonakjonanplutonium-239implutonium-240jendreninrautebenaeretali,neremaron,konkeinkomadmodikoilorankein.Unkobweenmaronjejjetaerjonwejonanplutoniumeoilorauteikiujbweenworkonnankake,komelelekoremonlok,imjerbalimwatwatimjemlokkorememeleiloaerjonwejonanplutoniumarmijkajojoremaronbukjeni.

6.Wawenantonelokjonanbaijeniloarmijkajojoimilomelanko.WatwatimjonaneorijerbalroanDOErarantonelokekkarnankwoneoweppenjenrouwanICRP.Jonaneoitulikinanbwinienjuonarmijrejantoneearjimweimjejjetimlukkunmelele.Antonekokonjonanradiationeoituloarorarbukijenaeremenono,imoronlok,rarjabtobrakkonkeiiokokajitokkakirejako.Ejjabjuonmeneoelapiloanjabbo-lelaolepenjerbalinetalekein,konkeantonkonanjonaneojuonrittoejkaniejlaplokjanantonkoekkarnanajirirokajojo.Ibbenlok,jonankeinri-scientistrorejaninjelakakeelapandriklokjenmenkorejaninkileikkijienwawenanarmijromona.

7.Ekatakkori-scientistrejaninmeleleikijienjejjetinjonelokimantonelokradiation.Ruoiankilenkoemojkomalimnanantonelokdretaneoelaptatailoanarmijejerwawa.Juonejkojerbaleprobablisticeoejkojerballemnakimukoktakkojenjidrikinradiologicalkokojerbaliiloekatakkein.Eojuonejkojerbalescenario,eoejkwalokkadkadinjetianroelapaerejerwawa,einwot

iio,armijrot(koraakemman),ijoejbedie,imkilananmona.EkatakkoanLLNLrejkojerbalewotprobablistic,botabrebanlukkunjimweimjejjetaerkamolijerbalkoaertokwotjenanietjonannanaermaroninantonelokjonanradionuclideskoiloenbwinier.Iloaerwonmantakkonscenarioeo,committeeinearantonekekajojororejmonajenkeinikkankowotmaroninbokjaonaniniuminjuoniio92-106mrem/y,ekkarnankilenanmona.

8.JipankoremaronkokomanmanejmournanarmijrorenajjeblakimjokweionRongelap.Committeeinejtomakkeunleplepnankomanmanlokmejatotoeoejkojerbalkonkojenpotassium,rebanjeletejmouranroionRongelap,ilomoleo,konanlonlokmenineddokkoimewamourmourlok,emaronkokmanmanlokejmournanaoleparmijro.PotassiumchlorideejjuonkooneoekkaaerkojerbaleiloUnitedStatesimejjabkauatatananejmourneejjerbalilouninwot.Keinkaruo,kareoiklokbwidrejeoejoranjenijokoarmijrejokweienajejelokjorannanejmouranarmij.Committeeinearkilekeiloaernajjolokbwidrejiniloijokorejoranitulon,ebareinwotjuonmeneoejjabemon,iloannajkakurekaanenekoimjanbokjuonieneoeaetoknananbarkokalbwidrej.

Bedbedionetalekoancommitteein,TableT-1,eoejtibdrikijonanradiationeojuonarmijenajbukijenanjeblakimjokweionRongelap,kajurinradiationeo,imiaenpaijeneo

PageT-5

TableT-1.KomolelekoKonJonanAnriRongelapEjerwawananRadiation

AjejkonanJonaneoKwojBok mSv/y (mrem/y)

I. JONANRADIATIONEBEDIEKADREDRE

A.Ejerwawajenijokoitulik 0.22 (22)

B.Radionuclideskoituloa 2.0 (200)

Subtotal 2.22 (222)

II. RADIATIONIKIJIENANKARAJERER ScenarioA ScenarioC

A.Ejerwawajenijokoitulik 0.11 (11) 0.11 (11)

B.Radionuclideskoituloa

1.menkojejoranlok 0.17 (17) 0.95 (95)

2.menkojejemeonon 0.0043 (0.43) 0.0043 (0.43)

Subtotal 0.29 (29) 1.06 (106)

TOTAL 2.51 (251) 3.28 (328)

ejwalokjenie.Ijinejkwalokajejinjonanbaijineoarmijkajojoremaronbokjenruoianekatakko:monakokijedmakekobamonakojenijokojet(scenarioA)jenRobinsonetal.(1993),immonakokijedmakeekkarnanRobisonetal.(1993)botaptokwotjenjonancaloriekokaniejkwaloktaeocommitteeinejkotmenekeejlaplokanjejjetoonkonanejmour(jonanooneinwotScenarioA).

Recommendations

Bedbedionekatakaketakeeoan,committeeeoearkomanejetkarokkoimreikuijinlori.

1.Kinwotjetmelelekorejaninlukuninalikarilowaweninelapankabukbuk,Committeeinearbakejetianarmijrorejjeblakimjokwe

ionRongelapremaronbuklaplokjan100-mremradiation,jonaneoemojkarokiloMOU.Melelein,armijrorenajjeblaknanRongelapimbokenaninaolebmenkokijierjenmonakoimkeinikkankoiloenekoremaronbokjonan,imejlaplokjen100-mremelaneejjelokjipankinpotassiumchlorideimejjelokjipankinmona.

2.ElanearmijinRongelaprorenajwonmanlokwotimlorwawenlajrakinjonaneoemojjonweiloaerjeblaknanRongelap,committeeinemojankamelimiruowawennanjiban

PageT-6

koimrejlajrakilal.

Mokajimkojerbaljuonmeneorejnaetanpotassiumchlorideeinwotkonnankadriklokbaijineoilomonakoetancesiuminekkawotanwalokijokoeworniimbobie.

Neenajdedelokjeblakeo,wawenkilenmonaeoenajjimetanincalories(oon)enajitokjenmonakoilikinimjimetanjenmonainaelonkein.

Jipankeinremaronbojrakelanneiloiiokotokelikri-scientistrorejjonelokbaijeneoimejdriklokjanjonenrejantonelokkio.

3.NankamolnanarmijinRongelapkejonankoakkarokkoanMOUeorarkomaneinwotcommitteeeoearkomelimkajojoianarmijroimrenajjeblakrenajaikiujimkakolkolimlaleneeworradionuclidesimbareinwotlalejuonjambolimkobojakbwerenmaronlalejonanplutoniummoktajenaerjeblakimnanbartokelik.Ilokobaiklok,jinointarrin80armij(jenbaelaneworanarmijeoej400)renajajejkinarmijrot(koraimemman)imjonaniniiokoaerinnemkakolkolemanaleniloiiootemjej.

4.CommitteeinearkabilokilojemlokinnanmaroniionkarokkojenMOUeo,bweaelonkoitueoniloRongelapimRongerikbwerenlikitiemo(''offlimit")akarmijenjabmaroninebbokmonajeni."Offlimit"eoemaronbojrokneiloaniiokojinoinetalekorejkwalokkejonanradiationarmijrokajojorejbukiedikjan100-mrem,jokronnerenajkarebbokmonajenenekoitueon.EkatakkokommonionRongelaprarletokjuonmeleleeoejimwenanantonelokjonankorejbukielanerenajjeblaknanRongelap.Committeeinearkabilokkejuonkateeoejwonmanlokwotnankileenekoiloailininbwerenmaroninkojerbaliimebbokmonajeniilorankanetokiman.Ekatakinejaikuijbweentibrikrikmelelekokonjonaneoremaronbokineemaronwalokjetwottokjenmakitkitkein.Einwotjuonjerbalinkate

eikiujintiljokiloanworjetmenininkotobarkoibbenaikuijkoanarmijroilobukonkoimkarokkojenrorejelaekkatakkoilomejatotoeo.Ibbenlokwot,committeeinearkwalokkeiloaerlalemelankonanmonakojemaronkanibweenwonmanlokwotbwerenmaronjonwejonanradiationeoilomeneneddokimilomejatotoeo.

5.Committeeenearkabilokkeeaikuijbweenworjikindaktoakkakolkolkonanetalewawenajmouranarmijrorejjeblak.Kakbiloklokinejjabekajaklokibbennaninmijinradiationakbweeniionmeninmelelekonerenajworinebatatokjenradiation.

6.Committeeinearkabilokebweenbo-lellokaerkarokikilenekatakkokonaolebmokitkitkoikijienjonwejonanradiationkoikotanBNLimLLNLkoimrarejaklokmokta.Kilenekkatakkeinraikuijbwerenkomman(karok)ippenScientificManagementTeameojenNationwideRadiologicalStudyeoanRMI.

1.IntroductionThephysicalandculturalcharacteristicsofthepeopleofRongelap,theirdiet,andtheircustomsasdistinctfromenvironmentalfactorsareimportantinestimatingpotentialradiationdosesafterreturntotheirnativeatoll.TheRongelappeopleareculturallyandethnicallydistinct.Someoftheirphysiologicalcharacteristicsmightalsodifferfromthoseofthe"standard"Americanandmightbeclosertothoseofthereference"Asianman"thantothoseoftheICRPstandard"referenceman''(Griffith,1994),onwhichmuchofourinformationforradiation-protectionstandardsisbased.ThecommitteeisawareofthosedifferencesandhasattemptedtokeepthemandtheconcernsoftheRongelapcommunityuppermostinmindduringitsdeliberations.

ConcernsofthecommitteeregardingthesettlementofRongelaparebothgeneralandspecific.Examplesofgeneralconcernsaretheprotectionofpeoplefromneedlessabove-backgroundradiationexposure;theuseofuniversallyaccepteddosimetrymethods;andtheproperapplicationofthemostcurrentstatistical,environmental,andbody-burdenmodelingproceduresinestimatingpotentialradiationdoses.Specificissuesaremorevariableandoftenintangibleandmustbeconsideredinrelationtoindividualandgroupneeds.TheyincludethespiritualconfluencethattheRongelappeoplefeelwiththeiratollhome,theirintimatedailyinteractionwiththeirenvironment,andthevariationsintheirdiet.ThepeopleofRongelaparehighlymobile,andtheirdietarypatternreflectstheirmovementsandactivities.Inbodytype,theaverageRongelapnativeisshortandtendstobeslenderuntilmarriage,afterwhichtheculturalvalueplacedonbeingwellfedbecomesapparent.Giventhoseconditions,predictingandmonitoringradiationexposuremusttakeintoaccountage,sex,andactivity

patternandmustalsofocusoncontext-specificbiophysicalandmetabolicprofiles,whichincludetheratiooflocallyproducedtoimportedfoodandotherdietaryvariables.

ThepeopleofRongelaphaveobviouslybeentraumatizedbytheirinvoluntaryinvolvementinnucleartesting.Theirfirstexileoccurredin1954,2daysaftertheU.S.nucleartestBRAVOresultedinwidespreadcontaminationoftheirislandhome.Theyreturnedin1957withassurancesthattheradiationlevelsontheiratollweresafe.Butin1985theybecameconvincedthatradiationcontaminationonRongelapwascontributingtomedicalproblems,andtheyagainmovedfromtheirhome,thistimetoexileontheislandofMejattointheKwajaleinAtoll.Sincethattime,theyhaveattemptedtodeterminewhethertheenvironmentofRongelapAtollsoil,birds,fish,andotherfoodstuffsissafeandtheatollthereforehabitable.Theystilldonothaveadefinitiveanswer;infact,theRongelapcommunityexpressesadegreeofdistrustofinformationreceivedfromDOE.MembersofthisNRCcommitteehopeindeed,anticipatethattheconcernsoftheRongelappeoplewill,toagreatextent,beallayedbytheknowledgethatthescientificactivitiesoftheDOEhavebeengivenathoroughreviewduringthecourseofthiscommittee'sdeliberations.

Thischapterpresentsanoverviewoftheculturalandenvironmentalfactorsthataffect

theresettlementofRongelap,includingtheirpotentialeffectontheestimationofradiationdosesofreturningRongelappeople.Boththecompositionoftheislandsoilsandthelocalclimateaffectweatheringandthedispersalofradioactivecontamination,andtheavailabilityofnativefoodsourcesandthedietaryhabitsofthepeoplearealsoimportant.ThischapterdrawsheavilyonseveralreviewsofthegeologyandculturalhistoryoftheMarshallIslands(Mason,1947;Wiens,1957;FosbergandCarrol,1965;Amerson,1969;Hezel,1983;BendureandFriary,1992;Simonetal.,1993).

Environment

ThemapshowninFigure1illustratesthelocationoftheRepublicoftheMarshallIslands(RMI)relativetotheotherislands,islandgroups,andlargerlandmassesinthePacificOcean.Figure2showsthepositionofthedifferentislandchains,atolls,andislandsoftheRMI(inthisreporttheRMIwilloftenbereferredtosimplyasthe"MarshallIslands",ashasbecomecommonpractice).TheMarshallIslandsconsistsoftwochainsofatollsrunningnorth-northwesttosouth-southeast:thewestern,Ralik("sunset")chainandtheeasternRatak("sunrise")chainareclearlydifferentiatedinFig.2.Thenumberofislandsintherepublicexceeds1,200.Onlyfiveareconsideredsingleislands;theothersaresetsofisletsgroupedinto29atolls,ofwhichRongelapAtollisone.Theareasofthevariousatollsrangefromabout0.5to16km2,andthoseofthelagoonsfromabout8.5to2,500km2.Thecapitaloftherepublic,Majuro,isonanatollthatliesapproximately3,800kmsouthwestofHonoluluand2,700kmnorthofFiji.

TheclimateoftheMarshallIslandsistropical.Theaveragedailytemperatureis27ºC(81ºF),andthetypicalrelativehumidityisabout80%.Theislandsarelow-lyingandthereforedonotinfluencelocalweatherpatternssubstantially.Rainfallhasawidegradient,from350

cm(138in.)ayearinthesouthernislandstoonlyabout110cm(43in.)inthenorthernmost;thisaccountsfortheheaviervegetationintheSouth.ThewettestmonthsareSeptemberthroughNovember,thedriestJanuarythroughMarch.Duringthewetseason,intenserainsquallsarefrequent.Full-blowntropicalstormsandtyphoonsarerare,buttheycanbedevastatingwhentheydooccurandcrosstheseunprotectedislands.

ThesoilsandvegetationoftheMarshallIslandshavebeenstudiedextensively(see,e.g.,FosbergandCarroll,1965).Virtuallyalltheislandshavewhitesand(coral)beaches.Soilsofthedeep-oceanatollsconsistalmostsolelyofsandyandcoarserparticlesofcalciumcarbonateascalciteandaragoniteandcontainsmallamountsofsubstitutedmagnesiumandstrontium.Silicateclaysappearundetectable,althoughtraceamountspresumablyoccurfromaccumulationofglobaldust.Organicmatterisrelativelyhighinthesurfacelayerbutdecreasesabruptlythroughanarrowtransitionzone.Theorganiccontentofthesurfacelayervariesfromatracetomorethan10%andisthesolesourceofcation-exchangecapacity.Calculatedratiosofthecarbontonitrogencontentofthesoilsvaryfromabout10:1to13:1andindicateadvancedstagesoforganicdecomposition.Phosphoruscontentrepresentsinputbynestingseabirdsatsometimeinthepastandvarieshighlyinamountfromsitetosite.Themake-upoftheislandsoilsandsub-soilscontributetoverylownaturalbackgroundradiationexposurerates;therearenonaturallyoccurringrockformationsthatwouldcontributetosuch

Figure1.CentralPacificOcean.

Figure2.RepublicoftheMarshallIslands

otherwisecommonlyoccurringradiationbackgroundssuchasthatduetoradon.

MostoftheoriginalvegetationofthenorthernMarshallIslands,especiallythelargerislands,hasbeenreplacedbycoconutplantations.Theseplantationsrangeindensityfromalmostcompletecoverinthemoisterregionstosparsenessinthedrynorthernatolls.Thegroundcoverunderthetreesrangesfromgrassandotherherbstoathicktangleofbushes,vines,andtrees,dependingontheparticularatollclimateandhowdiligentlytheplantationsaretended.Abeltofscrubforestissometimesleftaroundtheplantationsforprotectionfromwindandsaltspray.Thethickscrubforestsalongthefringeoftheislandscangivetheappearanceofimpenetrability.Inundisturbedareas,purestandsofthesoft-woodedtreesPisonia,Pandanus,orumbrella-likeOchrosiaarefoundwithmixedstandsofseveralhardwoodspecies.Theforestsusuallyhavedensecanopiesandlittleundergrowth.

RongelapAtollisintheRatakChainabout670kmnorthwestofMajuroandabout200kmsoutheastofBikiniAtoll.Itcomprisesabout50low-lyingislandswithatotalareaofabout9km2surroundingalagoonofabout1,000km2.ThelargestandbyfarthemostimportantislandisRongelap,withanareaofabout0.8km2.Theatollhasmoderateyearlyrainfall,about150-180cm(60-70in.).Themeanairtemperatureisabout27ºC(82ºF),andtheprevailingwindiseasttonorth.Theislandsarecoveredwithvegetationsomecoconutsandmuchnativebrushandwoodland;however,thelackofrainfallduringthelongdryseasonlimitsthekindsofplantsthatcanbegrown.FourteenbirdspeciesareknownonRongelapAtoll:eightseabirds,fourshorebirds,oneheron,andonedomesticfowl(Amerson,1969).

Culture

AnthropologistsestimatethattheresidentsoftheRepublicoftheMarshallIslandsfirstarrivedontheshoresoftheircoral-atollhomesabout2,000yearsago.Untilthelatterhalfofthenineteenthcentury,theysubsistedonseafoodsandbreadfruit,pandanus,coconut,andarrowroot.TheMarshallIslandswereneverunifiedunderasingleleader,althoughonechiefoftencontrolledseveralatolls,andattimesvirtuallytheentireRalikchainwasunderasinglechief.Chiefshadabsoluteauthority,buttheirwealthandpowerdependedontheloyaltyandtributepaymentsofthecommoners.

EuropeanculturalinfluenceswereabsentfromtheislandsuntilAlvarodeSaavedralandedinthewesternpartoftheMarshallIslandsin1529.AlthoughotherSpanishexpeditionslandedintheMarshallIslandsduringthe1500s,Spaindidnotattempttocolonizetheareaactively.SubstantialinterestintheareabyBritishandEuropeansgenerallywasnotshownuntilthe1830sand1840s,whenwhalersbegantofrequentthearea.TheislandsarenamedaftertheEnglishseacaptainJohnMarshall,whovisitedtheislandsin1788,butitwastheRussianexplorerOttovonKotzebuewhowaschieflyresponsibleforextensiveexplorationoftheregionbetween1815and1825andwhoseeffortsresultedinthefirstgoodmapsoftheislands.

WhalersandtradersbegantoexpandtheireffortsinthePacificearlyinthe1800s,buttendedtoavoidtheMarshallIslandsbecauseofitswidespreadreputationforviolence.RespondingtoEuropeanandAmericanabuseofislandwomenandtothekillingofsacredchiefsandvaluedcommoners,thepreviouslyfriendlyMarshallIslandsnativesbecame,forwesterners,themostfearedpeopleinMicronesia.Violencewasdeclining,however,bythe

westerners,themostfearedpeopleinMicronesia.Violencewasdeclining,however,bythetimethefirstProtestantmissionariesarrivedonEbonAtollinthe1850s.Missionariesweregivenamixedreceptionbylocalpeoplebutwithinafewyearshadattractedacoreofconverts.Inthe1860sand1870s,copraproductionreplacedwhalingastheprimaryEuropeanindustrialinterestinthearea.Thecopraindustryemployedlocalchiefsasintermediariesandgreatlyincreasedtheirpower,stability,andinfluence(Carucci,1988).

GermanypurchasedtheMarshallIslandsfromSpainin1885andlefttheadministrationofislandaffairstoagroupofGermantradingcompaniesthatfurtherstabilizedthepositionoftherulingchiefs.Germangovernmentofficialsdidnotarriveonthesceneuntil1906.Intheinterim,aseriesofstrugglesoverthetermsofwesterndominationtookplacebetweenAmericanmissionaries,Germantraders,andindependent"local"Europeantraders.In1917,theJapanesetookcontroloftheMarshallIslandsunderaLeagueofNationsmandate.Theyassumedcontrolofthecoprabusinessand,unliketheGermans,purchasedcopradirectlyfromthepeople,usinggroupsofresidentJapanesetraders,ratherthanrelyingsolelyonlocalchiefs.Thispolicy,withtheJapaneseinstitutionalizationofpositionsforagroupoflocalpoliticalelites,begantounderminetheunquestionedauthoritythatislandchiefshadgainedduringthecopraera.In1933,whenitbrokefromtheLeagueofNations,JapandeclaredownershipofMicronesia.Itdevelopedandfortifiedlargemilitarybasesonseveralatolls,usinglocallaborfromthroughouttheMarshallIslandsandKoreanandOkinawanexpatriates.TheUnitedStatesdefeatedJapanindecisivebattlesonKwajaleinandEnewetokAtollsin1944liberatingtheMarshallIslands,andruledtheareathroughanavalmilitarygovernmentuntilitwasgivenauthoritybytheUnitedNationsafterWorldWarIItoadministerthescatteredislandsandatollsofMicronesiaastheTrustTerritoryofthePacificIslands.

AdministrationofthetrustterritoryshiftedfromtheU.S.NavytotheDepartmentoftheInteriorin1951andremainedineffectuntiltheRepublicoftheMarshallIslandsgainedpolitical,ifnoteconomic,independenceundertheCompactofFreeAssociationthatwassignedwiththeUnitedStatesin1983andapprovedunderU.S.PublicLaw99-239onJanuary14,1986.

Ebon,Jaluit,Majuro,Kwajalein,andEnewetokwereMarshallIslandslocationsofinteresttoJapanese,European,andAmericancolonizersfromthe1850stothe1950s,butitwasnotuntiltheU.S.nuclear-testingeraafterWorldWarIIthatRongelap,Bikini,andUtirikjoinedEnewetokaslocationsofmajorconsideration.TheUnitedStatesbegannucleartestsin1946onBikiniAtollandexpandedthemtoEnewetoklatein1947.

TheconsequencesofthecontaminationofRongelapAtollandexposureofitsinhabitantsowingtosubstantialamountsofradiationfromradioactivefalloutonthelife-styleofthepeopleofRongelaparesummarizedinTable1-1.OnMarch1,1954,theBRAVOtestonBikiniexplodedwith3timestheprojectedintensity.TheunexpectedlyextensivefallouttraveledeastwardofthetestsiteandsubjectedtheresidentsofRongelapAtoll(includingAilinginaeandRongerik)andUtirikAtolltosubstantialamountsofradioactivecontamination.Withinabout5hafterthenucleartest,afinewhitepowderysubstancebegantorainonRongelapanditsinhabitants.Therehadbeennowarning,sothechildrenwereallowedtoplayinthe"snow";onlylaterdidtheinhabitantsofRongelaplearnthatthis"snow"wasdangerouslyradioactive.OnMarch3,1954,2daysafterthetest,64residentsofRongelapand18ofAilinginaewereevacuatedtoKwajalein;thenonMarch4,159residentsofUtirikwereevacuated.Includingfetuses,252residentsoftheseAtollssufferedwhole-bodyexposure,with

Table1-1.SummaryofResidencesofRongelapCommunitySinceBRAVOTest

Dates Residences

March1954

FalloutfromBRAVOtestoccursonMarch1;residentsareevacuatedtoKwajaleinAtollonMarch3

1954-1957

RongelapcommunitylivesonEjetIsland,MajuroAtoll

1957-1985

RongelapcommunityreturnstoRongelapAtollinJune1957andlivesthereuntilMay1985

May1985

RongelapcommunitymovesfromRongelaptoMejattoIsland,KwajaleinAtoll,onMay22

1985topresent

RongelapcommunitylivesonMejattoIslandwhileawaitingresettlementtoRongelapAtoll

thepeopleofRongelapreceivingestimatedexternalgamma-raydosesof190remandsubstantialinternalandexternalexposurefrombeta-emittingradionuclides(Conard,1992).Thelaterdevelopmentofnodularthyroiddiseases,includingsomemalignancies,resultedinunderstandableconcerninRongelapcommunityaboutlong-termhealth.

ThepeopleofRongelapreturnedtotheirhomeatollonJune29,1957,afteradecisionwasmadethatitwassafeforthemtoreturnundercontinuingradiologicalsurveillance.Later,theycametofeelthat''safe"wasrelativewhenunanticipatedmedicalproblemsbegantosurface.2Concernwasintensifiedbyreleaseofadditionalgovernmentreports,includingaMarshalleselanguagediscussionoftheradiationlevelsintheNorthernmollsoftheMarshallIsland(Bair,etal.,1982),

thatthepeopleofRongelapinterpretedasindicatinggreaterlevelsofcontaminationontheirhomelandsthantheyhadpreviouslybeenmadeawareofbytheU.S.DepartmentofEnergy.ThisreportwasinterpretedasindicatingthattheiratollwascontaminatedtothesamedegreeasBikiniwhichwasgenerallyconsidered"unsafe"forhabitation.Inadditiontotheseconcerns,urinesamplesanalyzedbyBrookhavenNationalLaboratoryin1984hadshownhigherlevelsofplutoniumthanhadbeenexpected(Conard,1992).OnMay22,1985,theRongelappeople,havinglostconfidenceintheadviceprovided

2AccordingtotestimonyofSenatorJetonAnjainbeforetheSubcommitteeonInsularandInternationalAffairs,Washington,D.C.,November16,1989.

bythedepartmentofEnergy,3lefttheirhomeatollforanewlocationonMejattoIslandinKwajaleinAtoll.Theincreasedplutoniumconcentrationsnowappeartohaveresultedfromurine-collectionproceduresthatresultedinspurioushighplutoniumlevels(Conard,1992)andthelevelsofradionuclidecontaminationonRongelaphaveproventobelowerthanthoseonBikini.However,theRongelappeoplenowwishtoeliminatealldoubtsaboutthehabitabilityoftheirhomelandbeforetheyreturnandhavechosentostayonMejattoIslanduntiltheyareassuredoftheradiologicalsafetyofRongelapIsland.

ThereviewofDOE'seffortintheradiologicalassessmentofRongelapbythisNationalResearchCouncilcommitteeisaimedatdeterminingwhetherthemethodsandpracticesundertakenbyDOEanditscontractorsarescientificallysound.

RadiationExposureandDose

RadiationdosesthatmightbereceivedinthefuturebypersonsofallagesareimportantissuesrelatedtotheresettlementoftheRongelappeople.AssessmentsofthesedosesprovideimportantbasesforestimatingthepossiblehealthrisksassociatedwithresidualradionuclidesonRongelapIsland.Sourcesofradiationcanbeexternal,internal,orboth.Forexample,someoftheRongelapinhabitantsexposeddirectlytotheBRAVOfalloutmaterialinMarch1954received,inamatterofafewdays,bumsontheirskinasaresultofbetaradiationemittedbyradionuclidesdepositedonskin,whereasothereffectsoftheearlyexposures,suchasdamagetothethyroid,werenotmanifestforseveralyears.Effectsonthethyroid,includingcancer,wereproducedbyradionuclidesofiodine(131I,133I,135I)thatwereabsorbedintothebody,weredepositedpreferentiallyinthethyroidaltissue,andbecamesourcesofchronicinternalradiationexposure.

Becauseofradioactivedecayandnaturalweathering,manyoftheradionuclidesintheinitialfalloutmaterialarenolongerpresent.ResettlementdecisionsmustincludeconsiderationofwhichradionuclidesarepresentandtheextenttowhichcurrentandfutureradionuclideinventorieswillcontributetoradiationdosesthattheRongelappeoplemightreceivefromexternalandinternalsources.OftheradionuclidesoriginallydepositedasfalloutfromtheBRAVOdetonation,only5radionuclidesarestillpresentinsufficientquantitiestocontributesignificantdosestoindividuals.Theseincludecesium-137,strontium-90,plutonium-239,plutonium-240,andamericium-241.Ofthetotaldoseestimatedforresidentsresettlingtheatolls,90%isfromcesium-137andover70%ofthatwillcomefromingestionofthenativefoods(KercherandRobison,1993).PossibleexposurepathwaysbywhichradiationdosesmightbereceivedarelistedinTable3.Strontiumisthesecondmostsignificantnuclidecontributingtotheestimateddose,alsofromingestioninfoodstuffs,andmightaccountforasmuchas2-5%ofthedose.Thetransuranicradionuclidesareestimatedtocontributelessthan5%oftheestimateddoseover50and70y.EstimateddosesfromstochasticsourcetermsandtheuncertaintiesinsuchcalculationshaverecentlybeendiscussedindetailbyKercherandRobison(1993).

3AsrelatedbySenatorAnjaininhistestimonytotheHouseCommitteeonAppropriations,May9,1991.

Table1-2.PathwaysofExposuretoRadiation

I. NATURALBACKGROUNDRADIATION

A Externalexposurea

B. Internalexposureb

II. RADIATIONFROMFALLOUTRADIONUCLIDES

A.Externalexposure

B.InternalExposureduetoIntakevia

1.Ingestionc

2.Inhalation

aAnnualexternaldosefromcosmicradiationis0.22mSv(22mrem).ExternalbackgroundradiationfromterrestrialsourcesisverylowinnorthernMarshallIslands(Robisonetal.,1993).

bAnnualinternalequivalentdoseisabout2mSv(200mrem)peryearfromnaturallyoccurringradionuclides,suchaspotassium-40,polonium-210,andlead-210inthediet(Robisonetal.,1993).

cIngestionincludesuptakefromterrestrialfoods,marinefoods,drinkingwater,andsoil.

Measurementsandanalysesoftheexposurepathwaysandthewidearrayoffactorsthatcaninfluenceboththeexposuresandtheradiationdosesreceivedfromtheseexposureshavebeenmadebyseveraldifferentorganizationsduringthelast40years.PeriodicmedicalexaminationsoftheRongelappeoplebegansoonaftertheirevacuationinMarch1954;theexaminationshavebeencarriedoutbymedicalstaffofBNLandhealth-servicepersonnelfromtheMarshallIslands.InadditiontoperformingmedicalexaminationsonpersonsexposedtotheinitialBRAVOfallout,theBNLmedicalstaffinitiated,in1958,periodicwhole-bodycountingtodeterminetheextentto

whichphoton-emittingradionuclidesfromtheinternalexposuresourcesshowninTable1-2werebeingincorporatedinpeople.Responsibilityformonitoringinternaldepositionofradionuclideswastransferredin1978totheBNLSafetyandEnvironmentalProtectionDivision,whichcontinuestocarryoutwhole-bodycountingandradionuclide-contentanalysisofurineandfeces.

On-siteenvironmentalsurveyshavealsoinvolvedseveralotherorganizations.MostoftheearlysurveyswereconductedbypersonneloftheU.S.NavalRadiologicalDefenseLaboratoryandtheRadiationEcologyLaboratoryoftheUniversityofWashingtonCollegeofFisheries.In1978,personnelfromEG&GCorporationperformedanextensiveairborneradiologicalsurveyofthenorthernMarshallIslandsintheBRAVOfalloutpath;inconjunctionwiththisextensivesurveyprogram,scientistsfromLLNLconductedland-basedenvironmentalsurveysofwater,soil,vegetation,andmarinespecies.Additionalsamplingtripsweremadein1986-1993.

ThiscommitteehasfocusedinlargepartonrequirementsspecifiedintheMOUrelatedtoannualradiationdoses,soilconcentrationsoftransuranicradionuclides(alpharadiation),andmeasurementsneededbeforeandafterresettlement.Thus,themeasurements,analyses,anddoseestimatesmadebyscientistsfromLLNLandBNLlieattheheartofthecommittee'sconcernsandresponsibilities.Theapproachesusedbybothorganizationsareillustratedin

Fig.3.LLNLscientistsobtaininformationontheradionuclidecontentofthevarioussamplesshown,andthencalculatepossibleradionuclideintakesonthebasisoftheamountsofintakeofair,water,andfood.Thisinformationisthencoupledwithmodelsofradionuclidemetabolismanddosimetrytocalculatetheinternaldepositionandretentionoftheseradionuclidesandtheresultinginternalradiationdose.SuchanapproachmakesitpossibletoestimatetheaccumulationofradionuclidesandtheconsequentinternaldoseintheRongelappeopleafterresettlement.

ThemeasurementsonindividualsbyBNLscientistsprovidedirectinformationonthepresenceofradionuclidesinthebody.Whole-bodycountingprovidesinformationonthetotal-bodycontentofradionuclidesthatemitphotonsofsufficientenergytoescapethebodyandbedetectedbythewhole-bodycounter.Analysesofradionuclidesexcretedinurineandfecesindicatewhichradionuclidesarepresentinthebodyonagivenday,regardlessofwhethertheyemitalpha,beta,orgammaradiation.Metabolicmodelsareusedtocomputethetotal-bodycontentofeachradionuclidemeasured.Oncethetotal-bodycontenthasbeenestimatedbywhole-bodycountingorexcretionanalyses,metabolicanddosimetricmodelsareusedtocomputetheradiationdoseresultingfromthisbodyburden.

Figure3.InternaldoseassessmentsforRongelappeople.

TheLLNLapproachcanbeusedtoestimateeitherpastorfutureenvironmentalexposureofpersonsonRongelapAtoll;theBNLmeasurementsprovideestimatesofthecurrentbodycontentofradionuclidesofinterest.Themeasurementsandmodelingapproachesusedbythetwolaboratoriesarerelatedandcanbeusedtoobtaincomparabledata.TheBNLmeasurementsoftotal-bodyradionuclidecontentatareferencetimeshouldprovidedoseestimatesthatagreewiththepredictionforthesametimeyieldedbytheLLNLmodelsbasedonenvironmentalpathways.

Itisobviousthatmanyscientificvariablesareassociatedwitheachapproach.Toprovidethebestinformationonradionuclideexposureandradiationdose,thesevariablesmustbedealtwithinscientificallyacceptableanddefensibleways.ThiscommitteehasreviewedwhathasbeendoneaboutdoseassessmentinthepastandwhatfurthershouldbedonebeforeresettlementoftheRongelappeople.Inparticular,theCommitteehasdirecteditseffortstofiverelatedsubjects:

Environmentalsamplingandanalysis.

Dietmodels.

Measurementsonhumans.

Dosimetryanditsapplication.

Uncertaintyandvariabilityindoseprojection.

Eachofthosesubjectsisexploredindetailinsubsequentchaptersofthisreport.

2.EnvironmentalSamplingandAnalysis

SamplingTechniques

ThischapterdescribesandevaluatestheLLNLenvironmentalsamplingprogram.Theassessmentisbasedona1.5-dvisitinOctober1993bytwocommitteememberstoreviewtheenvironmentallaboratorydirectedbyW.L.RobisonatLLNL,onevaluationofdataprovideddirectlytothecommitteebyW.L.Robison,andonevaluationoftheproceduresdescribedbyW.L.Robisoninhispublications(see,forexample,Robisonetal,1993).

DescriptionoftheLLNLenvironmentalsamplingprogram

TheLLNLenvironmentalprogramhassampledsoil,vegetation,water,andfoodstuffsonseveralislandsofRongelapAtollandnumerousotherislandsandatollsintheMarshallIslands.ThesemeasurementsprovideinformationontheradionuclidecontentofcomponentsoftheprojectedRongelapdietandonmaterial,suchassoil,thatmightbeinadvertentlyingested.LLNLhasalsoestimatedwhole-bodyexposurefromexternalsourcesofradiation.Ourreviewfocusesonsoilsamplingbecausesoilsarethemajorsourceofexposuretoplutoniumandonthesamplingofthreefoodstuffscoconut,breadfruit,andpandanusfruitsbecausethesearetheprimarysourcesofcesium-137exposureandaremajorcomponentsofboththeimported-foods-availableandlocal-foods-onlydiets(W.Robisonetal.1993).Inhalationandingestionviawaterdonotappearassignificantsourcesofinternalradiationexposure.

Thenatureofthesamplingprogramhaschangedovertime.Theinitial1978samplingprogram,whichcomplementedtheEG&G

Corporation'saerialgamma-rayspectroscopysurvey,wasundertakentocharacterizethedistributionandamountsofradionuclidesonmanyofthenorthernMarshallIslands,notjustthoseofRongelapAtoll(Robisonetal.,1993).Thatcharacterizationsamplingwasnotdesignedtoestimatethestatisticaldistributionsofradionuclidesontheisland;instead,thefocuswasonestimatingtheradionuclideconcentrationsinselectedsoilsandvegetationandthedepthprofilesofradionuclidesinthesoil.OnRongelapIsland,soilandfoodstuffsampleswerecollectedatarbitrarylocationsalongthelengthoftheisland.LatertripsusedavarietyofsamplingdesignstocharacterizedifferentaspectsofradionuclidedistributiononRongelap.Somesampleswerecollectedbywalkingalongtransects;otherswerecollectedatarbitrarilychosenlocations.Fine-scalespatialvariationwithina1x1-mareawassampledinoneregionoftheislandwithrelativelyhighactivity.TheregionaroundthevillageonRongelapIslandwasextensivelysampled.Suchcharacterizationsamplingprovidesinformationaboutthelocationsactuallysampled,butthereisnostatisticallyreliablemethodtodrawconclusionsaboutunsampledareasfromsuchsampling.

Inthelastfewyears,LLNLhasconductedsystematicsamplingfroma100-msamplinggrid,illustratedinFig.4,thatcoversthevegetatedareaoftheisland.Thegridwasoriented

paralleltotherowsoftreesinthecoconutplantation,andthegridoriginwasdefinedasthenorthernmostcoconuttree.Foreachpointinthesystematicsamplinggridatwhichtherewasacoconut,breadfruit,orpandanustree,asoil-depthprofilewasdeterminedbydiggingasoilpitandcollectingsoilfromdepthsof0-5cm,5-10cm,10-15cm,15-25cm,25-40cm,and40-60cm.Deepersoilfractionswerenotsampled,becauseobservedactivitiesinthesamplesfrom40-60cmwerelow.Inthecaseofafewgridlocations,nofoodstuffwasnearbyandnosoilprofilewascollectedatthesepoints.Iftherewasacoconut,breadfruit,orpandanustreeclosetothesamplingpoint,nutsandfruitswerealsocollected.Becauseofthewidespreadplantingofcoconutsacrosstheisland,coconutswereusuallyfoundclosetothedesignatedsamplingpoints,butbreadfruitandpandanustreesarelessfrequentandmorescatteredacrosstheisland.Thestaffthatperformedthefieldsamplingappeartohavetakenconsiderableefforttofollowthesystematicsamplingplan.Onthecommittee'svisittoRongelap,anumberofsiteswereobservedwhereaccesspathswerecutthroughthethickscrubtoreachsamplingpoints.InRobison'sopinion(W.L.Robison,personalcommunication,1993),allbreadfruitandpandanustreesinthevicinityofthedesertedvillageonRongelapIslandhavebeensampled.

EvaluationoftheLLNLenvironmentalsamplingprogram

Ingeneral,thegoalofanystatisticalsamplingprogramistodrawconclusionsaboutsomegeneralpopulationfromasetofobservedvalues.Astatisticalsamplingprogramcanbeevaluatedbyconsideringfourquestions:

Whatpopulationisbeingdescribedandisthatchoiceappropriate?

Aresamplelocationschosenwithanappropriatetechnique?

Isthenumberofsamplessufficienttoobtainthedesiredprecision?

Areappropriatetechniquesusedtodrawconclusionsfromtheresultsofsampling?

Asnotedabove,therehavebeentwosamplingprogramsonRongelap:theinitialcharacterizationsamplingatarbitrarilychosenpositionsandamorerecentsystematicsamplingbasedona100-mgrid.Thecharacterizationsamplingcannotbeusedtodrawconclusionsaboutunsampledlocations,becausetheprobabilitythatanindividuallocationorsourceofvegetationwassampledisunknownandarbitrary.Wefocusonthesystematicsamplingbecauseitcanbeusedtodrawconclusionsaboutunsampledlocations.Weconsidersoilsamplingandfoodstuffsamplingseparatelybecausetheirgoalsareslightlydifferent.

Soilsampling

Thegoalofthesoil-samplingprogramthatwasconductedbyLLNLwastodrawconclusionsaboutsoilradionuclideconcentrationsatanylocationonRongelap.Itshouldbenoted,however,thattheonlysoilssampledwerefromlocationsinthevicinityoffoodstufftrees.Suchaprotocolisconservativeandislikelytooverestimatesoiltransuranicconcentrations,inasmuchasthereissomeevidencethattheunsampledareas(betweentrees)arelikelytohavelowerconcentrationsoftransuranicsthanthesampledareas(W.L.Robison,

Figure4.MapofRongelapIslandwithsamplinglocationsindicated.

personalcommunication,1993).

Thepreferredmethodtodrawasystematicsampleistochooseastartingpointrandomly.TheLLNLgridwasstartedatthenorthernmostcoconuttree.Becausetheislandhasanirregularshape,thatcanbeconsideredasanacceptablechoiceofstartingpointandequivalenttoarandomstart.

Therearetwoseparateissuesconcerningcontributionsofsoilradionuclidestothetotaldose:theexposurefrom''average"conditionsandtheprobabilitythattherearelocalregionsofhighconcentrationsofradionuclides,commonlyreferredtoas"hotspots."Theestimatedcontributionsofsoilingestionandinhalationtothetotaldoseareconsideredsmall1.6%forallisotopes(Tables6and12inRobisonetal.,1993).Theconcernwithhotspotsisthatachanceencounterwithanunusuallyhighconcentrationofradionuclidesmightcontributeasubstantialdose;thisissueisofconcernmostlyforplutoniumandamericiumisotopesbecauseoftheirlongevity,althoughtheircontributiontothetotalaveragedoseisnormallyverysmall.InthecontextofthisreportandfortheformofradionuclidecontaminationonRongelap,ahotspotreferstothepossibilityoffindingasmallareawithsubstantiallyhigherradionuclideconcentrationthanthemeasuredaverage,nottoahotparticleasmightoccurfromfalloutfromareactoraccident.Initsdeliberationsthecommitteehasarbitrarilydefinedahotspottobeasmallregionwithradionuclideconcentrationofmorethan10timesthemeasuredaverage.

Theprobabilitythatahotspotissampledonasystematicsamplinggriddependsonthesizeandshapeofthehotspotandthespacingofthesamplinggrid(Gilbert,1987).Givenasinglecircularhotspotofradiusrandasquaregridofspacings,theprobabilitythatagridlocationfallswithinthehotspotcanbederivedtobe

fors>2r.Hot-spotsamplingprobabilitiesforaselectionofgridspacingsandthreeradiiaregiveninTable2-1.

The100-mgridusedonRongelapIslandhasamoderateprobabilityofsamplingalarge(28-m)hotspot,butaverylowprobabilityofsamplingsmallerhotspots.However,anextremelyfinegridwouldbeneededtosamplesmall(10-mor5-m)hotspotsreliably.Foragivenareatobesampled,thenumberofsamplesrequiredincreasesasgridspacingisreduced.Forexample,a20-mgridrequires25timesasmanysamplesasa100-mgrid.TheprobabilitiesinTable2-1werederivedforcircularhotspots;thedetectionprobabilitiesaredifferentforsquareorrectangularhotspots,buttheshapeofhotspotdoesnotaffectthebasicconclusionsofthesamplingprogram.

Anyreasonablesamplinggridisunlikelytodetectaverysmall,veryhotareathatmightberandomlyplacedonRongelapIsland.However,twoconsiderationssuggestthattheprobabilityoftherebeingsuchahotspotissmall:theBRAVOfalloutprecipitatedfromarelativelyhighelevationandwasfinelydispersed.Onestatisticalconsequenceisasmall-scalespatialcorrelationbetweenradionuclideconcentrationsinnearbysamples(thisisdiscussedingreaterdetaillater).

Table2-1.ProbabilityThataSingleCircularHotSpotofSelectedRadiusIsSampledbyaGridofSelectedSpacing

GridSpacing Probabilityofsamplingahotspotofradius:

28ma 10m 5m

200m 0.062 0.008 0.002

100mb 0.250 0.008 0.008

50m >0.990 0.03 0.03

25m >0.990 0.12 0.12

20m >0.990 0.20 0.20

aCircleofradius28mcoversabout1/4ha.

bGridusedbyLLNLsamplingprogram.

ThepreviousanalysisoftheprobabilityofsamplinghotspotsdidnotincorporateanyinformationfromtheobservedamountsofradionuclidesinRongelapsoil.Asecondapproachtoevaluatingtheprobabilityoftherebeinghotspotsistospecifyaradionuclideconcentrationthatdefinesahotspot,andthenask,whatistheprobabilitythattheremightbesuchaconcentrationinasmallrandomlychosenareabasedonobserveddistributions.Thecommitteeagreesthataconcentration10-timestheobservedmeanlevelisareasonabledefinitionofahotspot.ForRongelapIsland,thislevelofconcentrationforplutoniumwouldbeabout35pCi/g.Theobserveddataforsoilconcentrationscanthenbeusedtoestimatetheprobabilitythatthesoilplutoniumconcentrationinasmallareamightexceed35pCi/g.

Ifsoilplutoniumconcentrationswereknowntobenormallydistributed,thedesiredprobabilityofagivenconcentrationcanbe

calculatedfromthecumulativedistributionfunctionofthenormaldistribution.However,probabilityplotsofthesoilplutoniumdata(e.g.,Robisonetal.,1993,Fig.10)suggestthatneitheranormalnoralognormaldistributionisappropriatetoestimateprobabilitiesintheextremeuppertailofthedistribution.Onesolutiontothisproblemistofindatransformationofthedatathatoptimallyfitsanormaldistribution,thenestimateprobabilitiesusingthetransformeddistribution.Onebroadclassoftransformationsthatcanbeusedistheclassofpowertransformations:

Alogtransformationcorrespondstol=0,thesquare-roottransformationcorrespondstol=0.5,andnotransformationcorrespondstol=1.Theoptimaltransformationtonormalitycanbedefinedas1)thelthatmaximizesthecorrelationbetweenthetransformeddataandnormalorderscores(Stoline,1991),or2)thelthatproducestransformeddatawithaskewnessclosestto0.Theseapproachesareusedwithtwosamplesofsoilplutoniumdata:the22observationsfromthesystematicsamplinggridand110observationsfrommappedlocationsacrossRongelap.

Becausethemeanandstandarddeviationareestimatedfromthedata,thereissomesamplingvariationintheestimatedprobabilities.Thissamplingvariationissmallerinlargersamples.Anupperconfidenceboundonthehotspotprobabilitycanbecalculatedusingtablesbasedonnon-centraltdistributions(OwenandHua,1977).

Theoptimaltransformationstonormalityaredifferentforthetwogroupsofdata.Boththecorrelationandskewnesscriteriaindicatethesamechoiceoftransformation:l=0.8istheoptimaltransformationforthegriddata,whilel=0.4istheoptimaltransformationforthelargerdataset(Table2-2).Bothsetsofdataindicatethattheprobabilityofahotspotisextremelysmall,1in100,000orless.Upper99%confidenceboundsonthehotspotprobabilitiesarealsosmall,40in100,000or13in100,000,dependingonthechoiceofdataset(Table2-2).Theexactvaluesofthehotspotprobabilitiesandupperconfidenceboundsdodependslightlyonthechoiceoftransformation,buttheyareallsmall.IftheobservedvaluesofsoilplutoniumconcentrationsaretakenasrepresentativeofsoilplutoniumconcentrationsinunobservedareasofRongelapIsland,thentheprobabilitythatasmallareacontainsahighconcentrationofplutoniumisextremelysmall.Thenumericalvaluesofhotspotprobabilitiesdependontheextrapolationfromthedistributionofobserveddatatothedistributionofhighconcentrations.Becausethe

assumedcriticalvalue(35pCi/g)ismuchgreaterthanthelargestobservedvalue,someformofextrapolationisnecessarytomakethecalculation,butitisverydifficulttoverifythevalidityoftheextrapolation.

Foodstuffs

ThesamplingoffoodstuffonRongelapismoredifficulttoevaluatebecausenoquantitativegoalspecifiedtheprecisionrequiredforthesamplingprogram.Forexample,asurveytoestimatethemeanconcentrationofplutoniuminsoilmightspecifythatthestandarderrorofthemeanistobelessthan1pCi/m2,andthisrequiredprecisioncouldthenbeusedtocalculatetherequirednumberofsamples.Thequality-assuranceplanfortheLLNLprogram(W.L.Robison,personalcommunication,1993)specifiedacceptablecountingerrorsforeachsample,buttheseprovidednospecificationofthedesiredaccuracyforestimatesofpopulationparameters.Thepopulationparametersusedinthedoseassessmentarethemean,variance,andtypeofdistributionofradionuclideconcentrationsinfoodstuffs.SamplenumbersoffoodstuffandsoilsareshowninTable2-3.

Attentionisfocusedonsamplesizestoestimatethecesiumconcentrationinfoodstuffsbecause,accordingtothedoseassessment,cesiuminfoodstuffscontributesalargefractionofthetotaldose(Robisonetal.,1993).Thecommitteeestimatedmeanconcentrationsbecausethedosetothemaximallyexposedresidentdependsmoreonthemeancesiumconcentration

Table2-2.Probabilityofhotspotsexceeding35pCi/gofPuonRongelap.

Datafrom100mgridonRongelap(n=22).

l* r**Estimatedprobability upper99%confidencebound

optimaltransformationtonormality:

0.8 0.986 0.00000 0.0004

othercandidatetransformationstonormality:

0.6 0.981 0.00000 0.0020

0.7 0.985 0.00000 0.0009

0.9 0.984 0.00000 0.0002

1.0 0.981 0.00000 0.0001

DatafromalllocationsonRongelap(n=110)

l* r**Estimatedprobability upper99%confidencebound

optimaltransformationtonormality:

0.4 0.996 0.00001 0.00013

othercandidatetransformationstonormality:

0.2 0.989 0.00039 0.00292

0.3 0.994 0.00006 0.00093

0.5 0.995 0.00001 0.00002

0.6 0.992 0.00000 0.00000

*lspecificesthetransformationtonormality.

**risthecorrelationbetweenthetransformeddataandnormalorder

scores;valuescloserto1indicatebetterfittoanormaldistribution.

andondifferencesindietandindividualphysiologyamongtheRongelapnativesthanonthevarianceincesiumconcentrationinfoodstuffs(Robisonetal.1993).

Theexpectedwidthofa95%confidenceintervalforthemeanisoneofseveralapproachestodetermininganadequatesamplesize.Onecriterionmightbethatthesamplebelargeenoughfortheexpectedwidthtobesmallerthanthepopulationstandarddeviation.Astrictercriterionmightbethattheexpectedwidthbesmallerthanhalfthepopulationstandarddeviation.

Table2-3.EnvironmentalSamplesandInterviewsContributingtoRongelapDietInformation

EnvironmentalsamplesanalyzedbyLLNLasofOctober1993*

Total Onsamplinggrid

Csindrinking-coconutmeat 293trees 134trees

Csinpandanus 77trees 22trees

Csinsoils(0-5cm) 659samples 186samples

Puinsoils(0-5cm) 208samples 22samples

Samplesusedtoestimatevariabilityamongindividuals:

Diet 34Ujelangwomen

Biologicalhalf-life(cesium) 23Marshallesemen

*NumbersmayvaryfromRobisonetal.,1993,becausesometreeshavebeensampledmorethanonce.

Theexpectedwidthofaconfidenceintervaldependsonthevarianceofthesamplemean,whichdependsonthesamplesizeandpropertiesofthepopulation.Thevarianceofthemeanfromasystematicsamplecanbewrittenas

wherenisthesamplesize,Nisthepopulationsize, isthepopulationvariance,andrwSthecorrelationamongvaluesinasystematicsample.Thecorrelationrwisusuallyunknown,butifthepopulationisinrandomorder,rw=0.ThenumberofcoconuttreesonRongelap(N)isabout10,000,muchlargerthanthesamplesize.Hence,thesamplingvariancesimplifiestothatforrandom-sampling:

Ifthedatacanbetransformedtoanormaldistribution,thenthewidthofa95%confidenceintervalforthetransformedmeanisgivenby

wheret0.975,n-1isthe97.5percentileofastudenttdistributionwithn-1degreesoffreedom.

Thesamplestandarddeviationisaslightlybiasedestimatorofs,butanunbiasedestimate

canbeobtainedbymultiplyingsbyacorrectionfactor(GurlandandTripathi1971)togettheexpectedwidthsshowninTable2-4.TheexpectedwidthsinTable2-4arecalculatedforsimplerandomsamplesofvarioussamplesizesfromaninfinitepopulationandareexpressedrelativetothepopulationstandarddeviation.Expectedwidthsareslightlysmallerforfinitepopulations.Atleast19samplesareneededfortheexpectedwidthtobelessthanthepopulationstandarddeviation.Atleast65samplesareneededtomeetthestrictercriterionofawidthlessthans/2.With150samples,theexpectedwidthisabouts/3(Table2-4).

Thenumberofsamplesofdrinkingcoconutsfromthe100-msystematicgridislargeenoughtoprovideareasonablypreciseestimateofmeancesium.Theexpectedwidthofthe95%confidenceintervaliss/3.ThenumberofpandanusandbreadfruitonRongelapissmaller;however,inthevicinityofthevillageallormostofthesetreeshavebeensampled.Inthiscase,thesampleestimatesarealsopreciseestimatesofthepopulationmean,althoughthesamplesizesaresmaller.Itisdifficulttoevaluatetheprecisionoftheestimatedcesiumconcentrationsintheotherfoodstuffsusedinthedoseassessmentbecausetherewasnoprobabilitysamplingandthepopulationsizesaregenerallyunknown.

Themeancesium-137concentrationinmanyfoodstuffsislikelytobepoorlyestimatedbecauseofthesmallsamplesizes.Forexample,thereare5samplesofarrowroot,7samplesofporkmuscle,6samplesofporkliver,and4samplesofporkheart(Robisonetal.,1993;Tables20andB-1).BecausestandarddeviationsarenotcomputedbyRobisonetal.(1993;Table20),itappearsthatthereareevensmallernumbersofsamples,perhapsonlyoneeach,ofpapaya,chickenmuscle,chickenliverandchickengizzard.Chapter6onuncertaintyandvariabilityindoseprojectionexploressomeoftheconsequencesofthesmallsamplesizes.

Analternativecriteriontoassessasamplingplanisthatitprovidesufficientlyaccurateestimatesofextremevaluesinapopulation.ThiscriterionisespeciallyrelevanttoRongelapresettlement,wheretheMOUisconcernedwiththedosetothemaximallyexposedresident.Onestatisticalevaluationofwhetherextremevaluesareadequatelysampledisbasedonconfidenceboundsontheproportionofapopulationthatexceedsthelargestsamplevalue.Thesecanbecalculatedwithoutassumingthatvaluesinapopulationhaveaspecificdistributionalform(e.g.,normal)byusingnonparametrictolerancebounds(HahnandMeeker,1991).Thetoleranceboundthatisrelevanthereistheestimate,withgivenconfidence,oftheproportionofthepopulationthatexceedsthelargestobservedvalueinasample.

Foraninfinitepopulation,a95%upperconfidenceboundontheproportionofindividualsthatexceedsthelargestsamplevalueisgivenby

wherenisthesamplesizeandFisthe95thpercentileofanFdistributionwith2,2ndegreesoffreedom(HahnandMeeker1991).ForafinitepopulationofsizeN,theupper95%confidenceboundcanbeexpressedasanumberofpersons.Itisgivenbythesmallest

Table2-4.ExpectedWidthsof95%ConfidenceIntervalsfortheMeanandNonparametric95%ConfidenceBoundsontheNumber(inthePopulation)thatExceedtheLargestObservationintheSample

samplesize

ExpectedNumberinthepopulation(sizeN)thatexceedwidththelargestobservedvalueinthesample(sizen)

n (s) N=50 N=100 N=200

5 2.6 22 45 90 45.1

10 1.5 12 25 51 25.9

15 1.12 8 17 35 18.1

20 0.94 6 13 27 13.9

25 0.84 5 10 22 11.3

50 0.56 0 5 11 5.8

75 0.43 3 7 3.9

100 0.40 0 5 3.0

150 0.32 3 2.0

200 0.28 0 1.5

500 0.17 0.6

ainpercentoftotal

number,k,thatsatisfiesthefollowingexpression:

Themaximumobservedconcentrationofcesium-137inthemeatofdrinkingcoconutsthoseharvestedatthepropertimefordrinkingtheliquidinthecoconutwas14.7pCi/g(decaycorrectedto1995).Itis

reasonabletotreatthepopulationsofsoilandcoconuttreesashavinganinfinitesizebecausetherearemanymorelocationsandcoconuttreesthanweresampled.AccordingtoTable2-4andthesamplesizesgiveninTable2-3,itisunlikelythatthemeatfromanydrinkingcoconutswillbeaslargeasthemaximumobserved,14.7pCi/g,butitisreasonablycertainthatnomorethan2%ofthecoconuttreeswillhavevalueslargerthanthat.Ifoneassumesthatthereareabout100pandanustreesonRongelap,itisreasonablycertainthatthefruitsofveryfewtrees(nomorethanthree)havecesiumconcentrationslargerthan33.3pCi/g,thehighestconcentrationfoundinthe77measuredtrees.

Incontrast,measurementsofthedietandbiologicalcharacteristicsoftheRongelappeopleprovidemuchlesspreciseestimatesofmeanorextremevalues.Dietestimatesarebasedon34women;biologicalhalf-lifeestimatesofcesiumarebasedon23men.Theexpectedwidthsofconfidenceintervalsforthemeansare75-85%ofthepopulationstandarddeviation(Table

2-4).Ifthepopulationsizeistakentobe200,therearelikelytobeabout22people(about10%ofthepopulation)withdietsorbiologicalhalf-livesmoreextremethanthelargestvaluesfoundinthesample.Samplesofabout25personsofapopulationofthissizedonotprovidegoodestimatesofeitherthemeanorthemaximum.

Theresultsfromasystematicsamplearecommonlytreatedasthoughthesamplewasasimplerandomsample.ThisistrueoftheLLNLRongelapdoseassessment,theworkplanoftheRongelapAtollResettlementProject(S.Simon,personalcommunication,1994),andouranalysisillustratedinTable3-1.Analyzingdatafromasystematicsampleasthoughtheycamefromasimplerandomsampleisstatisticallyjustifiableifthreeconditionsaremet(Gilbert,1987):

Thereisnotrendinthepopulation.

Therearenostratainthepopulation.

Valuesareuncorrelatedacrossspace.

Eachofthoseissuescanbeexaminedwiththeavailabledata.Weconcentrateonplutoniuminthesoil,becauseofitsinteresttothepeopleofRongelap,andcesiuminthesoil,pandanus,anddrinkingcoconuts,becauseitcontributesthemajorfractionofthecalculateddose.Pandanusanddrinkingcoconutswerechosenbecausetheyarelargecomponentsofthedietandhaverelativelyhighcesiumcontent,accordingtotheLLNLdietmodelanddoseassessment.

Threepossibletrendswereconsidered:variationsinconcentrationsofradionuclidesacrosstheislandinaroughlyeast-westdirection,acrosstheislandinaroughlynorth-southdirection,andfromthebeachlinetothecenteroftheisland,measuredbythedistancefromasamplingpointtothenearestbeach.Noneofthefourvariables(plutoniuminsoilorcesiuminsoil,pandanus,ordrinkingcoconuts)showsanytrendsinmeanconcentrationintheeast-westnorth-southdirections

(Figs.5,6,7,and8).However,thevarianceincesiumincoconutsishigherattheeasternandwesternendsoftheislandthaninthecenteroftheisland.Exceptforcesiuminpandanus,theconcentrationsincreasewithdistancefromthebeach.

Thestructureofthesoilinthevillageareaisquitedifferentfromthatinthecoconutgroves.Inthevillage,thesoilhasmuchlessorganicmatter,hasbeendisturbedbyconstruction,andofteniscoveredwithlayersofcrushedcoral.Soilsurfaceconcentrationsofcesiumandplutoniumaresignificantlylowerinthevillageareathaninthecoconutgroves(Figs.5and6).Asmallnumberofpandanusandothertreesgrowinthevicinityofthevillage.Theconcentrationsofcesiuminthesetreesaresimilartothosefoundinotherareasoftheisland.

TheonlysetofdatathatcanbeusedtodrawconclusionsaboutunsampledplacesonRongelapisthesystematicsample,becausetherearenotabletrendsandstrataacrosstheisland.Meancesiumandplutoniumconcentrationscalculatedfromalltreeandsoilsamplesdifferfromthosecalculatedfromthesamplinggridalone.Sitesandtreesonthesamplinggridcoverallareasoftheislandwithaboutequalprobability.Thecharacterizationsamplescoversomeareasoftheislandexcessively,suchasthevillagearea(forsoils)andthecenteroftheisland(fortrees).Oversamplinginthismannerbiasesthemean.Forexample,oversamplingofvillageareas,aswasthecaseforcesiumandplutoniummeasurements,canreducetheoverall

Figures5.TrendsinthesoilplutoniumconcentrationonRongelap;[Pu]inpCi/g.

Figure6.Trendsinsoilcesiumconcentration(0-5cm)onRongelap;[Cs]inpCi/g.

Figure7.TrendsinpandanusCsconcentrationonRongelap;[Cs]inpCi/g.

Figure8.TrendsincesiumconcentrationinmeatofdrinkingcoconutsonRongelap;[Cs]inpCi/g.

meanbyasmuchas25%.TheLLNLdoseassessmentshoulduseeitherestimatescalculatedfromjustthesamplinggridtodescriberadionuclideconcentrationsinthesoilandcoconuttreesorusearea-weightedaverages.Forpandanus,breadfruit,andotherfoodstuffs,forwhichmostorallofthepopulationhasbeensampled,itisappropriatetousealltheavailabledata.

Spatialcorrelationwasexaminedonisland-wide,10-m,and10-cmscalesbyestimatingisotropicandanisotropicsemivariograms.Semivariogramsarecommonlyusedtodescribespatialvariationinsoilproperties(fordescriptionsandusesofsemivariograms,see,forexample,Burrough,1991;Cressie,1991;andWarricketal.,1986).Insuchplots,departureofthecurvefromthehorizonalasymptoteindicatesapositivecorrelation.Small-scalecesium-concentrationdataareavailablefrompit22,a1x1-mareainaregionoftheislandwithrelativelyhighconcentrationsofcesiuminthesoil,andtwo100x100-msites.Withinpit22,soilsamplesweretakenat10-cmintervalsinasquaregrid.Intheotherregions,soilsamplesweretakenat10-mintervals.Onesitewasentirelyinthecoconutgrove;theothercrossedfromthevillagetothecoconutgrove.Becauseofthedifferencesincesiumconcentrationsinvillageandcoconut-grovesoil,onlythefirstsitecanbeusedtoestimatethespatialcorrelations.Therewasnodetectablespatialcorrelationontheisland-widescaleorthe10-mscale,butcesiumconcentrationsshowedsubstantialpositivecorrelationsinpit22(Fig.9).Siteswithin40to50cmofoneanotherhavesimilarcesiumconcentrations.Ifthespatialcorrelationfoundinpit22ischaracteristicoftherestoftheisland,thissmall-scalepositivecorrelationdecreasestheprobabilitythataverysmallhotspotexists.

Conclusions

ThesystematicsamplinggridusedbyLLNLisawidelyused,

commonlyacceptedtechniquetosampleenvironmentalcharacteristics.Onlythedatafromthesamplinggridshouldbeused,however,toestimatethemeanandvariance,unlessmostoralloftheitemsonRongelaparesampled,e.g.,breadfruitandpandanustrees.

Thesamplesderivedfromthesamplinggridaresufficienttoprovidereasonablypreciseestimatesofthemeanconcentrationsofradionuclidesinthemajorfoodstuffs.Estimatesofthevarianceinthedistributionsofradionuclidesintheenvironmentarelessaccurate,buttheyhaveamuchsmallerimpactontheconclusionsofthedoseassessment.

Therearetrendsinsoilcesiumandplutoniumandcoconutcesiumconcentrationsfromthebeachtoinland.Somecareisneededtoanalyzethesedatabecauseofthetrends.Thecesiumconcentrationofpandanuscanbeanalyzedasthoughthedatawerecollectedfromanisland-widesimplerandomsample.

Analyticaltechniques

ThissectionbrieflyevaluatestheanalyticalmethodsusedbyLLNLtodeterminetheconcentrationofradioactiveisotopesofconcerninsoil,sediment,seawater,andbiotasamplesfromRongelapAtoll.TheproceduresusedaredescribedingreatdetailinanLLNLreport(Wongetal.,1994),andthemethodusedforpreconcentrationofplutoniumfromlarge

Figure9.Semivariogramforcesiumandincesi-umconcentration.Small-scalespatialcorrelationestimatedfrom10-

cmgridsamplesinpit22:a.[Cs];b.In[Cs].Medium-scalespatialcorrelationestimatedfrom12-

mgridsamplesincoconutgrove:c.[Cs];d.In[Cs].Linesshowthefittedsphericalsemivariograms.Semivarianceslessthanasymptoticsemivarianceindicatepositivespatialcorrelationatthatdistance;[Cs]inpCi/g.

volumesofnaturalwatershasbeenpublished(Wongetal.,1978).MuchadditionalinformationwasobtainedfromextensivediscussionswithW.L.RobisonoftheHealthandEcologicalAssessmentDivisionofLLNL.

Ingeneral,standardwell-provenprocedureswereusedinanalysesfortheisotopesofconcern.Internalstandardsandcarrierswereusedasappropriate.Samplestobeanalyzedforplutoniumwereconcentratedbymanganesedioxideprecipitationiftheywereaqueous(Wongetal.,1978)orashedanddigestedinconcentratednitricacidiftheyweresoil,sediment,orbiota(Wongetal.,1994).Afterdissolution,theplutoniumwasseparatedbyanionexchange(Dowex-1),electroplatedontoametaldisc,andanalyzedbyalphaspectrometry.Samplepreparationandanalysisforamericiumweresimilartothoseforplutonium,exceptthatachelatingion-exchangeresin,octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphineoxide(TRU-Spec),wasusedinsteadofastrong-baseanion-exchangeresin.Again,thesamplewaselectroplatedandcountedbyalphaspectrometry.

Theothertwoelementsofprimaryconcernareinthesestudieswerecesiumandstrontium.Cesium-137inaqueoussampleswasmeasuredbyextractionontoamicrocrystallineammoniumphosphomolybdatecation-exchangerfollowedbypurificationfrompotassiumandrubidiumbysorptionontoastrong-acidcationexchangeresin(BIO-REX40)andtheprecipitationofthecesiumwithchloroplatinicacidforbetacounting.Thecesium-137contentofmostsoilandbiotasamplescanbedetermineddirectlybygamma-rayspectrometrywithoutanypreparation.

Determinationofstrontium-90contentofaqueoussamplesrequiredpreconcentrationbycoprecipitationwithammoniumoxalate,dissolutioninnitricacidandprecipitationasstrontiumnitrate,dissolutioninwater,andprecipitationofstrontiumcarbonate.

Pretreatmentofsoilandbiotasampleswasthesameasthatofplutoniumsamples.Thestrontiumshouldbepresentasastrontiumnitrateprecipitateinthenitricacidsolution;itwasseparated,dissolvedinwater,andprecipitatedasstrontiumcarbonate.Afterdissolutioninhydrochloricacid,thestrontiumsolutionswereallowedtostandatleast18dforthestrontium-90-yttrium-90equilibriumtobeestablishedandthencountedonalow-backgroundbetacounter.Theyttrium-90contentmustalsobeconsideredinthedeterminationofstrontium-90concentration.

Conclusions

Themethodsusedintheseanalysesarewellestablished,provenprocedures,manyofwhichweredevelopedbyLLNLandusedthereforanumberofyears.Wheretherearealterationsintheseprocedures,theygenerallyinvolvetheuseofnew,moreefficiention-exchangeresinsandextractionsolvents.Thewrittenproceduresareverythorough,firstdescribingthechemicalbasisforthemethodandthengivingacareful,step-by-stepsetofinstructionsthatareeasytounderstandandfollow.Also,possiblesourcesoferrorarerecognizedandcautionedagainstatappropriatepointsintheprocedure,forexample,theneedforcareinpipettingatracersolution,tocolor-codewashbottlestoavoidmistakesaboutwhattheycontain,andtouseaTeflon-coatedstirringrodintransferringsolutions.Thesemightseemtobeinconsequentialpoints,butmanyanalyseshavebeenabortedbyfailuretoobservesuchseeminglytrivialpoints.

Theanalyticalprocedureswerecarriedoutunderanextensivequality-assurance-quality-

controlprogram(Mountetal.,undated).Inaddition,asplit-sampleprogramwasunderwaywiththeNationwideRadiologicalStudyoftheRepublicoftheMarshallIslands(S.L.Simon,personalcommunication,1994).Limitedresults(S.Duffy,personalcommunication,1993)fromtheanalysisofcoconutmilkandmeatinthissplit-sampleprogramindicateacceptableagreementbetweenthetwolaboratories.Becauseofthesoundchemistryandthoroughnessoftheanalyticalprocedures,theeffectivenessofthequality-controlprogram,andtheearlydatafromthesplit-sampleprogram,thereislittlereasontoquestiontheaccuracyandprecisionoftheLLNLanalyticaldata.

Moreover,anearlierconcernofthecommitteeappearstohavebeeneliminated.Foratime,therewasaconsiderablebacklogofunanalyzedsamplesthatwerecollectedinagridsamplingprogram;lackofdataonthosesampleswouldhaveimpairedproperdoseassessmentonRongelap.Fortunately,analysisofthesamplesisnowessentiallycomplete,andalltheplannedanalyticalresultsareavailableforuseindoseassessment.

3.DietaryModelsThetechnicalactivities(environmentalsamplinganddosemeasurement)neededtosupportanydecisiononresettlementarethemselvesdiverseandscientificallysophisticated.However,theintegrationandinterpretationoftheresultingdatainamannerthatpermitsreliabledoseprojectionsdependonthedevelopmentofscientificallysounddietmodelsappropriatetothepopulationofconcern.

Thedevelopmentofamodelthatprovidesusefulpredictionsofdietaryintakeunderavarietyoflifecircumstancesisnoteasy.Nevertheless,accurateestimatesofexposuretoradioactivitydependonarobustdietmodel,particularlyinthenorthernMarshallIslands,wherealargecomponentoftheradiationdoseappearstobecontributedbycesium-137,whichisconcentratedincommonlocalfoods.AnumberofgroupshavestudiedfoodhabitsintheMarshallIslands,includingKotzebue(1821,1830),Paulding(1831),Finsch(1893),Snefft(1903),KramerandNevermann(1938),Lawrence(1943),Murdock(1943),Mason(1947,1967),Tobin(1952,1953),andMaramba(1960).However,thedatafromthosesourceshavelittlevalueforuseindoseprojectionsbecausetheyareold(and,therefore,notintunewithchangesindietaryhabits)andgenerallynotquantitative.ThemostrecentinformationondietthatmightberelevanttotheresettlementofRongelapcomesfromtheMarshallIslandsNationalNutritionSurveyof1991,whichfocusedonthegrowthofchildrenandinfantfeedingpractices(RMIMinistryofHealth,1991);italsodoesnotprovidequantitativeestimatesoffoodintakes.

OnlytwosurveyshaveprovideddatathatareofpotentialvalueinquantitativelyestimatingadultdietaryintakesandarereasonablyappropriatetotheproposedresettlementofRongelap:a1978surveyoftheUjelangcommunitybyMicronesianLegalServicesCorporation(Robisonetal.,1980,1992,1993)anda1970ssurveyofthedietaryhabitsofthenorthernMarshallesebyNaiduetal.(1980).Athoroughassessmentofthestrengthsandweaknessesofbothsurveysisneededtointerpretanycalculationsofradiologicalexposurebasedontheirdata;suchanassessmentisprovidedbelow.

UjelangDietModel

TheUjelangdietmodelisbasedonasurveyoftheUjelangcommunityin1978bytheMicronesianLegalServicesCorporation(MLSC)staffwiththeaidofaMarshallIslandsschoolteacheronUjelang(Robisonetal.,1992,1980).Althoughthesurveyhadweaknesses,itwasinmanywayssuperiortonationaldietsurveysintheUnitedStates(HumanNutritionInformationService,1988;PublicHealthService,1979;ScienceandEducationAdministration,1980).Inparticular,thesesurveyssufferfrompoorparticipationrates,non-optimalstatisticalselectionprocedures,lackoftimeliness,orinherentlimitationofthemethods(GuentherandTippett,1993).ThedietsurveysoftheRongelapandrelatedpopulationsprovidecriticaldata

fortheevaluationofprojecteddosesbecauseoftheimportanceoftheingestionpathwayforexposuretoradionuclides.InviewoftheneedforprecisedosecalculationstoexaminetheconditionssetforthintheMOU,therequirementsforanacceptabledietsurveyfarexceedthoseforusualsurveys.

ThepositiveaspectsoftheUjelangdietsurveyincludethefollowing:

Thesamplingplanwasreasonable.Itwasbasedonanenumerationofallmembersofthepopulation.Subjectsweregroupedbyageandsex,andanattemptwasmadetointerviewatleast20%ofthesubjectsineachcategory.

Thepurposeofthestudywascarefullyexplainedtoallsubjects.Anofficial(amagistrate)emphasizedtheimportanceofgivinganaccuraterecallthatneitherignoredsomefoodsbecausetheywere''unimportant''noroverestimatedintakeofotherstopleasetheinterviewer.

Trainedinterviewersconductedalltheinterviews,sodatacollectionwasstandardizedandfairlyuniform.

Thesurveyinstrumentwasdetailedandsoshouldhavehelpedsubjectstorememberdetailsabouttheirfoodintake.Anattemptwasmadetohelpsubjectsinestimatingservingsizesbymakingcomparisonstoa12-oz.can.Subjectswereaskedtoestimateintakesfordays,weeks,andmonths.

Thesurveyteamidentifiedthesituationinwhichlocalfoodsweremostapttobeconsumed(i.e.,famine)andaskeddetailedquestionsonboththatsituationandthetypicalsituation.

TheMLSCdietsurveyinUjelangalsohadshortcomings,aspresentedbelow,anditsdeficienciesmustberecognizedwhenusingthedatagenerated,especiallybecauseextrapolationsfromdiethavesucha

criticaleffectonestimateddosesofingestedradionuclides.EachdeficiencymustbeconsideredinrelationtodifferentcontextsofMarshalleselife,butthefirstfourpresentedpotentiallyhavethemostimportantimpactsfromthepointofviewofdataapplication.

Althoughthemagistrateemphasizedtheimportanceofgivinganaccuraterecalloffoodseaten,theclimateofthesurveywaspoliticallycharged.Pritchard,whoconductedthesurveyfortheMLSC,toldthecommunitythat"anearliersurveyhadreportedwhatseemedtobeanunrealisticallyhighconsumptionrateforlocalfoods,particularlycoconuts,andifthesereportswereutilizedinassessingtherisk,therewasalmostnolikelihoodthatpeoplewouldbeabletoliveonEnjebiintheforeseeablefuture"(Pritchard,1979:2-3).BecausetheexiledEnewetokpeoplewould,atthatpoint,havedonevirtuallyanythingtoensuretheywouldbereturnedtoEnewetokAtoll(Carucci,1992),presentingtherequestfordietaryinformationinthiswayalmostcertainlyaffectedhowpeoplerespondedtothesurvey,particularlyresidents

whoselandsweremainlyinthenorthern(Enjebi)halfofEnewetokAtoll.

Lackofinformationonsubjects'livingsituations,especiallyduringfamineperiods,limitstheinterpretationofdatafromthissurvey.AllUjelangresidentsover1yearofageareknowntohaveconsumedlargequantitiesofarrowroot,outofnecessity,duringafamineperiodin1978(theyearbeforethesurvey).ButUjelangpeopleareextremelymobile.SomeofthosereportingnoarrowrootconsumptionmightnothavelivedonUjelangatthetimeofthefamine.Theresearchersdidnotkeeptrackofresidents'histories,sothecausesofdiscrepanciesarenotimmediatelyapparent.AsnotedinthestudybyNaiduetal.(1980),typeAcommunities(outerislands,whereresidentsdependonimports,notlocalfood)havesubstantiallydifferentpatternsoffoodusefromothercommunities.Duringthe1978foodshortage,overadozenUjelangresidentstendedtappedcoconuttrees.Generalcoconutconsumption,particularlyofcoconutliquidandsproutedcoconuts,increaseswhenmenmakecopra.Duringfamines,coconutisincludedindishesnotdescribedinthesurvey(pikukuk,mokkir,andaojek).ThattheseareUjelangfoodswithdistinctivenames,perhapsnotknowntotheMarshallesetranslator,contributedtotheirnotbeingreportedinthesurvey.

Thereportedlowenergyintake(1392kcal/d)oftheMarshallesewheneatingan"indigenous"dietissurprisingandprobablyunrealistic(Robisonetal.,1992).Thisestimateislessthantheaveragerecommendedenergyintakefor25-to50-y-oldmenbutnotwomen,1,800and1380kcal/d,respectively(FoodandNutritionBoard,1989).Theserecommendedintakesconstituteageneralguideline,buttheirapplicabilitytoUjelangresidentsisnotknown.Thefoodintakeofsubjectsconsumingtheindigenousdietof1,392kcal/dwasreportedtobeonly40%oftheirtypicalintake,3490kcal/d(Robisonetal.,1992).Thatinvertstheprobableenergyrequirementsofadults.Island

residentswouldexpendmoreenergyincollectingandpreparingindigenousfoodsthaninpreparingimported,oftenpre-packagedimporteditems.Adeficitinenergybalanceofthetypeindicatedbythedatawouldhavecausedthementoloseabout4lbofweightperweek.Therearenoreportsofsuchrapidweightlossduringthefamineperiod.

Anothermajorlimitationofthissurveywasthefailuretodistinguishfoodeventssystematically.Theresearchersdidaskabouttimesoffamine,aswellaseverydayconsumptionwhenimportedfoodswereavailable,buttheyfailedtodifferentiatebetweenfoodintakeatfeastsandonweekends,asopposedtoweekdayconsumption.Feasts,particularlyfirst-birthdaycelebrations,occurfrequently,andfoodintakeincreasesatthesetimes.Foodintakealsoincreasessubstantiallyduringthe4-monthperiodduringwhichlocalpeoplecelebrateChristmas(October-January),Enewetokliberationday,andEaster.AsthroughoutMicronesiaandPolynesia,foodintakeisgenerallygreateronweekendsthanonweekdays(Pelletier,1987).Foodintakealsovarieswithoccupation.Theintakeofparticularfoodsincreasegreatlyduringcopraproduction,andonextendedfishingandgatheringexpeditions.Inthissurvey,subjectsmighthavereportedtypicalintakesonweekdays,weekends,feastdays,orhypothetical"average"days.ItislikelythatUjelangresidentsvariedintheirinterpretationofa"typical"day.Subjectsmightormightnothaveincludedintheirestimatesspeciallaborconditions,weekdaysandweekends,feastdays,andthelengthycelebrationofChristmas.

Theagestratificationsby5-yincrementsarecompromisedbythefactthat"peopleonUjelang[are]unsureoftheirownandtheirchildren'sagesandallthesefiguresshouldprobablyberead±1or2[years]"(Pritchard,1979a).Parentalestimatesof"ages"areagaininexactandprobablyshouldbe±5[years]''(Pritchard,1979a).Thus,thebalanceofsubjectsineachcategorymightbeskewedfromthe20%representationclaimedinthereport.

Interviewersweretrainedtoperformdietaryinterviews,buttheywerenotexperiencednutritionistsordietitians,norweretheyfamiliarwithUjelangfoods.Eventhelocal"Marshallese"schoolteacherwasan"in-married"manfromPingelapAtollwhospokeanacceptablevariantofthelocaldialect.Inaddition,thesurveyinstrumentwasadministereddifferentlyovertime.Somefoodswereaddedastheinterviewersbecameawareofthem(Pritchard,1979a:15);othersweremeasuredmoreaccuratelyasthesurveyprogressed(Pritchard,1979a:4).Duringthefirst2d,questionsweretranslated,oftenwithextensiveexplanation,andtheanswersweretranslatedbackfortranscriptiontothesurveyform.Afterthefirsttwodays,theMarshalleseassistant,whowasunfamiliarwiththeUjelangdialectofMarshallese,simplystatedthequestioninMarshalleseandtranslatedonlyanswersorrequestsforfurtherexplanationtotheinterviewer(Pritchard1979a:2).Thus,manylinguisticandnonverbalresponseswentuntranslatedafterdaytwo.

ThesurveyinstrumentwasbasedonageneralknowledgeofMarshallIslandsfoods,butitfailedtoexhibitaspecificknowledgeofthefooditemsonUjelangAtoll.Neitherthenamesofthefoodsnortheirmodesofpreparationwereaccountedforbythesurveyteam.Researchers"addedthetermmadotooursurveythesecondday,[but]theremaybesomeunderreportingsincethewordusedonUjelangisKiraj"(Pritchard,1979a:15).Attimes,thesurveyteam'slackofknowledgeoflocalmethodsofpreparingindigenousfoodscaused

themtooverlooknumerousvariablesthatdirectlyaffectfoodconsumptionandcomposition.Forexample,porkismostoftenpreparedbyboiling,buttheinterviewersstatedthatporkwasbakedorreheatedinafryingpan(Pritchard,1979a:16).Similarproblemsaroseinrelationtococonuts,whichatthattimewereconsideredthemostcriticallocalfoodinrelationtoradioisotopeuptake(Pritchard,1979b).Inspiteofacommendableattempttocorroboratethegenerallevelsofcoconutconsumption(Pritchard,1979b),confusionpersistsinrelationtothestagesofcoconut,thephysicalcharacteristicsofcoconutatdifferentstages,andhoweachcoconutstageisrelatedtopatternsoffoodpreparationandconsumption(Pritchard,1979b:13,17).Someofthefooddesignations,suchas"Marshallesecake,"andquestionsusedinthesurveywereprobablyconfusingtotheinterviewees.Marshallesecakehasmultipleforms.Althoughonetypeincludessubstantialquantitiesofcoconut,anotherismadewithoutshreddedcoconut.Mokkir,aUjelangcreation,consistsofcakebrokenintobite-sizedbitsandmixedwithwarmcoconutcream.Thiscommonfeastfoodwasnotmentionedamongthelistoflocalconsumables.Tosomeextent,theinterviewerstriedtocompensateforthesesurveylimitationsbyaskingpeopletoestimatetheamountsofcoconutcreamaddedtofoodingeneralforasetperiod(Pritchard,1979b);peoplewhodidnotpreparethefoodwouldhavedifficultyinansweringthisquestion.

Althoughafamiliarvessel(a12-ozcolacan)wasdisplayedtohelppeopletoestimate

quantitiesofingesteditems,noattemptwasmadetodemonstratehowmuchfoodordrinkcouldbecontainedinit.

Thesurveypopulationwassmall.Unintentionalcollusionduetotheinterviewsituationsmighthaveskewedsomeresults.Forexample,inonesituation,bothsubjectAandherdaughter,subjectB,reportedexactlythesameintakesoffoods(W.L.Robison,personalcommunication,1993).Theirresponsesaresuspect(althoughnotimpossible)becausein1978subjectAwasalarge,maturewomanandsubjectBwasslight.Extraneousvaluesmightalsohaveskewedtheresultsofthissmallsurvey.Forexample,subjectC,theyoungersisterofsubjectB,in1978sharedthesamecookhouse.Sheestimatedthatsheconsumed180gofbakedbreadperday;thatis2timesthenexthighestwoman'sestimateinthecommunityandover8timesthequantitybeingconsumedbysubjectB.AnotherexampleofquestionabledataconcernssubjectX,whoclaimedthatsheconsumed63gofarrowrootperdayaspartofhernormaldiet,notinfamineconditions.Thatis3timesthenexthighestwoman'sestimateinafieldof38inwhich32womenclaimedthattheyconsumednoarrowroot.AtranslationproblemprobablycausedsubjectXtomakeherestimate.Whateverthecause,theestimateskewedthedataonarrowrootconsumption.

Asistypicalofdietsurveys,thisonemadegreatdemandsonsubjects'memoriesandabilitiestoquantifyfoodintakes.Itisdoubtfulthatsubjectswereabletorememberallthefoodsthattheyconsumedortoestimateservingsizesaccurately.InrecentsurveysintheUnitedStatesandNorthernIreland,averagesubjectsreportedenergyintakes18-19%belowmaintenanceintakes(Mertz,1992;Lichtmanetal.,1992;Livingstoneetal.,1990).However,theextentofunderestimationvariesamongsubjects.Lichtmanetal.(1992)reportedthatagroupofobesesubjectsunderreportedtheirenergyintakeby47±16%.Robisonetal.(1992and1980)notedthatthe

estimatedfoodintakewasabout20%greaterforwomenthanmen.Otherinvestigatorshavenotedthatmoreaccuratedietaryinformationwasobtainedfromwomenthanmen(Rideretal.,1984;Yuhasetal.,1989).Thatmightreflectgreaterattentiontofoodbywomen.IntheMarshallIslands,foodpreparationdependsontheoccasion,butmaturinggirlsandyoungwomendomostoftheregularcooking.Generally,peoplerememberfoodsconsumedasmajorcomponentsofmealsmoreaccuratelythanfoodsandbeveragesconsumedas"accessory"foods(GregerandEtnyre,1978;Mullenetal.,1984).FoodeventsarehighlyvariableintheMarshallIslands,andagreatdealisconsumedadhocaspeoplemovearoundthevillageacceptinginvitationstoeatatrelatives'housesorastheyworkinthebush.Moreover,itisrudetoeatelsewhereandnotbringfoodhometoshare.Therefore,wheninterviewswereconductedinhouseholdsettings,theintakeof"snack"foodsandbeveragesmightwellhavebeenunderestimated.Itisparticularlydifficultforsubjectstoreportpastbehaviorsaccurately(Bradburnetal.,1987;Dwyeretal.,1987);themostrecentfamineexperienceswereslightlymorethanayearbeforethetimeofthesurvey,andthelowerfoodintakesandincreasedvariabilityinthe"famine"statisticsmightbeexplainedinpartbythetimelapse.

Theremightbeatleastthreeothersourcesoferrorinextrapolationfromthe1978surveyoftheUjelangdiettothe1990sRongelapdiet.First,thedietobservationsweremade

whentheUjelangcouncilmemberswereabsentfromtheisland.Iftheirdietdifferedfromthenoncouncilpopulationandifthecouncilmembersshouldbeconsideredpartofthetargetpopulation,thenthesamplingwasbiased.Second,extrapolatingfromUjelangtoRongelapassumessimilarecologicalsituationsanddietaryhabits.Third,theuseofa1978dietsurveytoestimatefoodconsumptioninthe1990sassumesthatdietarypracticeshavenotchangedsubstantially.Thepresenceandpracticalconsequencesofthesepotentialsourcesoferrorareunknown.

TheUjelangdietmodelrepresentsthebestdataonwhichtobaseestimatesofaRongelapdiet.Althoughithasseverallimitations,itisasgoodasmanymajordietstudiesintheUnitedStates(HumanNutritionInformationServices,1988;PublicHealthService,1979;ScienceandEducationAdministration,1980).Evenwithitsdrawbacks,itwasthelogicalandappropriatechoiceforRobisonetal.(1992)tousetoestimateexposuretoisotopesiningestedfoodandbeverages.However,theprovisionalcharacterofthisdietmodelnecessitatesarecognitionthatabsoluteanswersontheaverageintakeandonmeasuresofvariabilityareunlikely.Thus,thecommitteefeelsthatanadditionalwaytousetheUjelangdietmodelisinpreparationofscenariosthatallowforvariationsinenergyintake,foodselection(e.g.,importsvs.localfoodsandsuchactivitiesascoconut-gathering),andeffectsofpotentialremediationactivities(suchasapplicationofKClfertilizertosoil).Table3-1givesseveralpotentialscenarios;morecouldbedevisedtoreflecttheconcernsandlifestyleofthemembersoftheRongelapcommunity.

BNLDietModelfortheNorthernMarshallIslands

ThisdietmodelthathasbeenappliedtopeopleofthenorthernMarshallIslands,wasdevelopedbyNaiduetal.(1980)ofBNLbasedonintermittentobservationsbyasurveyteamandqualitativedata

collectedinaformalsurvey.Thesurveyteamlivedinlocalcommunitiesforbriefperiodsandreportedthefood-preparationtechniquesandfoodpatternsoftheislanders.Systematicrecordsoffoodintakewerenotmadebythesurveyteam.Thus,theirreportwiththoseofMuraietal.(1958),Pollock(1970),Carucci(1980),andMaifeld(1982)andthehistoricalaccountsmentionedearliercontributetoacomprehensivesetofqualitativedescriptionsofthedietaryhabitsoftheresidentsoftheMarshallIslands.However,thequalitativedatacollectedbytheBNLteamarenotusefulformakingquantitativeestimatesofintakeofspecificnutrientsorevenfoods.

ThefollowingpointsareimportantfortheinterpretationanduseoftheBNLdata:

LiketheUjelangsurveydata,theBNLstudyisdated(datawerecollectedbefore1980).FoodhabitshavechangeddramaticallythroughoutthePacificasresidentshavebecomemoreintegratedintotheworldeconomy(BindonandBaker,1985;Pelletier,1987;McGarvey,1991;Tayloretal.,1991).Localpeopleareprobablysubstantiallylessdependentonindigenousfoods,particularlyfoodsthatrequireextensivepreparation,thantheywereatthetimeofthissurvey.

Table3-1.PotentialDietaryScenariosConsideringVariationsinEnergyIntake,FoodChoices,andRemediationwithKCl

Ujelanglocal&importeddieta

Ujelanglocal-onlydieta

Local-onlydietb

Coconut-collector'sdietc

Local-onlyfromnorthernisletsd

Local-onlywithKClappliede

(A) (B) (C) (D) (E) (F)

Energyintake

kcal/d 3,208 1,392 3,208 2,018 3,208 3,208

137Csintakef

Bq/d 31 78 180 152 291-1084

32

Foodintake(g/d)

Total 3,490 1,541 3,270 2,517 3,270 3,270

Fish 42 90 208 180 208 208

Seafood 27 118 272 118 272 272

Meat 26 50 116 50 116 116

Eggs 18 149 59g 59g 59g 59g

Pandanus 9 32 75 32 75 75

Breadfruit 27 93 215 93 215 215

Coconut 202 415 957 1,690 957 957

Marshcake

12

Fruits 7 14 32 14 32 32

Squash 1 3 6 3 6 6

Arrowroot 4 47 109 47 109 109

Beverages 947 530 1,222 230 1,222 1,222

Importedfoods

2,168

aRobisonetal.,1992;1993,Tables5and6.

bLocaldietadjustedtoprovidethesameenergyasUjelanglocalandimporteddiet(ColumnBx2.305).

cEnergyintakeofUjelanglocaldietincreasedbychangingintakeoffish(two-fold),coconutjuice(five-fold),drinkingcoconutmeat(five-fold),sproutedcoconut(five-fold),consumptionofturtleeggs(-90g),andbeverages(-300g)tomakedietquantitieslogical.

dLocaldietinColumnCbutwithpandanus,coconut,andarrowrootcollectedinnorthernisletsofRongelapandRongerikAtolls.Kohn(1989)estimatedwhole-bodydoses2-9timesgreaterthanonRongelapIsland.

eLocaldietinColumnCwithassumed90%lossofcesium-137incoconutbreadfruitandpandanusbecauseofKClfertilization(Robisonetal.,1993).

fCesium-137intakeadjustedto1995concentration.

gEstimateofturtle-eggconsumptioninlatestUjelangdiet(ColumnB)isunrealistic;eggintakereducedto9g/d.

TheBNLstudyshowsnoevidenceofasamplingplan.Thenumberofsubjectsinterviewedandthedemographicsituationofeachsubjectwerenotdefinedinthemajorreportofdata.

Thesurveyteamdidnotseemtoappreciatetheprinciplesforestimatingaveragediets.Theysuggestedthatitwouldbeimpossibleforanoutsideobservertochoosea"typicalfamily"tomonitorfordietaryobservation,althoughthe"typicalmaximum"or"typicalminimum"dietwouldstandout(Naiduetal.,1980).Onceasamplepopulationwasdefined,normativevaluescouldbeeasilyderived.Withoutademographicprofile,itisimpossibletodefinethe"meaning''oftheBNLdataortosubdividethedataandderiveseparateprofileswithsensitivitytosex,age,residence,day-to-dayoccupation,andseasonalorweeklyvariations.

Thesurveyinstrumentwaspoorlydesignedtoelicitquantitativeinformation.Forinstance,Question28asked"Howmanypumpkinsdoyoucookforyourfamilyduringatypicalyear?"andQuestion37asked"Howmanytimesdoyoumakeamealofpigduringthetypicalmonthoryear?"(Naiduetal.,1980).Suchquestionsdidnotelicitquantitativeinformation,e.g.,onthesizesofpumpkinsorpigsoronthesizesoftypicalservingsformalesandfemalesoradultsandchildren.Thequestionsalsomadeunrealisticdemandsonthesubjects'memories;estimatingconsumptionofanitemforatypicalmonthoryearisverydifficult(Dwyeretal.,1987),especiallywhenvariationsofresidence,activity,andseasonarelikely.Theinterviewershadnosystematicmechanismtoallowrespondentstostandardizequantities.Moreover,adultsmadetheestimatesofconsumptionforchildrenalikelysourceofreducedvariabilityinsampling.

TheamountoffoodpreparedwasmeasuredintheBNLstudy,notfoodintake.Itisdifficulttoestimatethepercentageofpreparedfoodactuallyconsumedbyhumans.Refrigerationatthetimeofthesurvey

wasavailableonlyinurbanareas.Theleftoverswereprobablyfedtopigs,chickens,anddogs.Noestimatesofwasteshavebeenmade,soconversionofpreparedfoodtoconsumedfoodisveryquestionable.Cyclesoffeastandfaminehaveimmediateeffectsonwasteandfoodconservation.Thedifferenceinsamplinge.g.,assessmentofpreparedfoodversusconsumedfoodaccountsforalowerestimateofcoconutintakeandhenceofingestedisotopesintheUjelangdietmodelthanintheBNLdietmodel.ItisalsologicalthattheUjelangdietdata(basedonfoodconsumption)correlatemorecloselywithmeasuredisotopebodyburdenthanBNLdata(basedonfoodpreparationwithnocorrectionforwaste).

ThemostusefulinformationfromtheBNLsurveyisderivedfromthediscussionofseasonalvariabilityoffoodintake.Unfortunately,thesurveyprovidesnoinformationondifferencesinfoodintakebasedonage,sex,residencehistory,occupationalpursuit,weekdayversusweekend,ordinarydayversusfeast,etc.

ThedelineationofdietpatternsonthebasisofthreehypotheticalcommunitytypesprovidedbytheNaiduetal.studyispotentiallyuseful,butthebasisoftheclassificationandtheactualcommunitiesthatweresurveyedwerenevermadeapparent(Naiduetal.,1980).The

creationofhypotheticalCommunitiesA,B,andCbytheauthorsinanattempttobeobjectiveultimatelycompromisedthescientificutilityoftheresearch,inthatthemaintenanceofcommunityandrespondentanonymitymeansthatthedatacouldnotbereanalyzed.AlthoughthecontrastbetweenCommunityAandCommunityCrepresentsthelogicalextremesintheMarshallIslands,CommunityBisanomalous.Itwasnotdescribedadequatelytomakethedatauseful.Generally,adensepopulationissubjecttoheavyfishingpressureandreducedfishingsuccess.Nonetheless,CommunityBisdefinedas"overpopulated"withlowavailabilityoflocalfoodandyetwith"excellentfishing";about33%ofitsdietcomesfromfish.Itisextremelyunlikelythatresidentsofthe''overpopulated"areasoftheMarshallIslands(Uliga,Majuro;andEbeye,Kwajalein)haveaccesstoenoughfishtomakeup33%oftheirdiet.Tomakethedatausable,termslike"overpopulation"needtobequantified,thecommunitiesneedtobeidentified,andforpurposesofRongelapresettlementthelivingcircumstancesintheresearchcommunitiesneedtobecomparedwiththeexpectedsituationonRongelapAtoll.

TheBNLsurveydatahaveotherseriousanomaliesthatareunexplainablewithoutfurtherinformation.Forexample,areasonablehypothesis(onthebasisofinformationfromotherdietsurveys)wouldbethatconsumptionofcoconutingeneralandcoconutcreaminparticularwoulddeclineasacommunitybecamemoreurban.Indeed,inCommunityA(withalowpopulationdensity),about10,000gofgratedcoconutforcream(milk)perpersonwasproducedperpersoneachyear;andinCommunityB(highdensitybutfishplentiful),gratedcoconutproductionusedforcreamdroppedto2,500g/yareasonableexpectation.InCommunityC,however,withhighpopulationdensityandlowavailabilityoflocalproduce,gratedcoconutforcreamproductionwasestimatedtobe45,000g/y.Thisishighlyunlikely:coconutsarevirtuallyunavailableineitherEbeyeor

Uliga,andwhenavailabletheyareexpensive.SuchanomaliesdecreaseconfidenceintheBNLdietsurvey.

ThedietarydatageneratedbytheBNLdietsurveyarenotquantitativeandthereforeareofonlysupplementaryvalueinestimatingdietaryintakeoftheMarshallese.

ExtrapolationsfromDietModels

ThelackofacomprehensiveDOEresearchplantorelatetheBNLandLLNLresearchendeavorsformallyhasproducedmixedresults.TheUjelangdietmodelandtheLLNLenvironmentalinformationcanbecombinedtoyieldwhole-bodyburdensofcesium-137thataregenerallyconsistentwiththeBNLmeasuredvalues.However,somefeaturesofthedietmodelareclearlyunrealistic.Therearemanydietarycomponentsinthemodel,andsingleconfirmationsolelybyBNLmeasuredvaluescannotbetakenasconfirmationthatthedetailsofthedietarymodelarecorrect.Inparticular,thereislittleevidencethattherelativeimportanceofsomelocalfoodsinthedietisbeingaccuratelyassessed.

Dietinformationnowbeingobtainedmighthelptoreducetheuncertainties,buthistoricallyBNL'srelianceonLLNLdietinformationfromtheUjelangdietsurveytocalculatepotentialplutoniumintakethroughfoodhasbeenariskystrategy(Sunetal.1992b,1993).Potentialsforsoilcontaminationduringoutdoorfoodpreparationwererecognizedasearlyas1985(Lessardetal.,1985,asquotedinSunetal.,1992a),butLLNLmeasurementswere

basedoncollectedfoods,ratherthanpreparedfoods.Indeed,radioactiveassessmentsoffoodspreparedunderlocalconditionsarelacking.Althoughimprovementsintheurine-collectionprotocolappeartohaveansweredquestionsaboutincreasedplutoniuminBNL'surine-bioassaymeasurements,absoluteassurancesaboutplutoniumintakefromfood(Conard1992:53)cannotbeanswered,givenourcurrentlackofknowledgeaboutMarshallesefood-preparationtechniques.

Theunanswereddietaryquestionsincludethese:HowaccuratelydoestheUjelangdietsurveypredictthepatternoffoodconsumptiononRongelap?HowhavenorthernMarshallIslandsconsumptionpatternssystematicallychangedsince1978?Howhaveouter-islandfood-preparationtechniquesalteredtheingestionofcesiumandplutonium?Robisonetal.(1992)recognizetheexistenceofproblemsinknowledgeoftheUjelangdiet.TheCommitteehopesthatafewoftheseproblemswillbesolvedthroughamoresystematicassessmentofMarshallIslandsdiets.

Recommendations

WerecommendthatacomprehensiveresearchplanbedevelopedtointegratetheBNLandLLNLresearchendeavors.Historically,thedietaryanddosimetricdatahavenotreachedtheiroptimaluse,becausewell-definedresearchobjectivesandprogramreviewhavebeenlacking.Acomprehensiveresearchplancouldhavebroughttheindividuallaboratoryeffortstogethertowardacommongoalwithgreatereffectthanthatachievedseparately.Thelaboratoriesshouldmakeampleuseofexpertsinnutrition,diet,dosimetryandintheculturalcharacteristicsofthelocalpeopleindevelopingtheircomprehensiveresearchplan.

Thefollowingsuggestionsmighthelpintheinterpretationofthetotal

datasetbutwillnotaltertheCommittee'sbasicconclusions.

Individualdietarydifferencesarenotwelldescribedinthecurrentdietmodels.Individualsdifferinbothtotalamountoffoodconsumedandchoiceofitemsinthediet.ThecesiumintakeofeachpersonintheUjelangsurveyshouldbecalculatedindividuallyfromfoodintakeandreportedintermsofgramsperdayandpicocuriesperday.ThisisunderwayatLLNL.Separatevalues(meansplusorminusstandardderivation)forfoodandisotopeintakesforeachageandsexgroupsshouldalsobecalculated.

Measurementoffoodpreparedandfoodleftattheendofmealsbeforeanimalsarefedwouldyieldinformationonwaste.Ifsuchmeasurementsweremadein10householdsunderavarietyofcircumstancese.g.,feastversuseverydayandweekendversusweekdayitwouldbepossibletoestimatewasteandapplythiscorrectionfactortotheBNLdietmodel.Theseestimatescouldnotbestatisticallyvalidated,buttheywouldprovideawaytoestablishclosercorrelationsbetweentheBNLdietmodelandtheUjelangdietmodel.ConsideringtheotherlimitationsoftheBNLdietmodel,however,suchcorrectionsmaynotbeconsideredworththeeffort.

ItisnotrealistictoexpecttheMarshallesetoreturntoatotallyindigenousdiet.Activeadultsneedmorethan1,392kcal/d(1,541g/d)theestimatedaverageenergyintakeofadultssubsistingonatotallyindigenousdietonUjelangbutareunlikelytoconsume6,000g/d,theapproximateamountconsumedbypeoplewiththehighestconsumptionintheUjelangsurvey(Robisonetal.,1993:37).Therefore,estimatingdietaryintakesfora100%indigenousfooddietisprobablynotuseful.Thebestwaytoestimatemaximumintakeofindigenousfoodisdebatable,butitmightbepossibletosurveyfoodintakeonUjaeorLaeAtoll.ResidentsoftheseouteratollsinthecentralwesternMarshallIslandsusemoreindigenousfoodsthanthoseofRongelapAtollbecausetheirfinancialresourcesaresmaller.

ThestudybyCalf(J.Calf,personalcommunication,1993)willupdateinformationondietaryintakeoftheMarshallesefrombefore1980to1993.Itshouldprovideimportantinformationoninfantfeedingpracticesandmighthelptoidentifyfoodintakesofchildren,youngsinglemalesandfemales,nursingwomen,adultmales,nonnursingfemales,andtheelderly.Suchdatawillyieldestimatesofvarianceinfoodintakeforeachgroup.Moreimportant,thissurveywasdesignedtoproviderealisticestimatesofenergyintakesforsubjectsofdifferentagesandshouldaccomplishthatgoal.However,thesurveyconductedbyCalfconsistingof1-ddietrecallsofallresidentsonMejattoduringMay1993willnotprovidedataonseasonalvariation.AstudybeingconductedbyBurtonandNerooftheUniversityofCalifornia,Irvine(Burton,personalcommunication,1993),althoughnotquantitative,willbeausefulsourceofsupplementarydataonshiftsinfoodintakeduetoseasonalvariations,feasts,andspecialactivities,suchasintensivefood-gatheringorcopraproduction.Thisinformationwillbehelpfulinformulatingpotentialdietscenariosinvolvingindigenousfoodsandpeoplewithvariedactivities.

AnaccountingofallshippingrecordsforimportedfoodsarrivinginMejattowouldprovideacross-checkofdatacollectedintheUjelangandCalfdietsurveysandprovideanothermeansofassessingtherelativeusesofimportedfoods.Thisaccountingshouldincludeallgovernmentsubsidies(U.S.DepartmentofAgriculture:schoollunchandsupplementalfoodsuppliesthatarepartofnuclear-relatedcompensations)andallpurchasedfoods.Somesortoffood-supplementprogramoragriculturalprogramwillbeessentialifenergyintakesaretobemaintainedafterresettlementofRongelap.

Dataontheradiationcontentofselectedpreparedindigenousfoodswouldaidintheinterpretationofcurrentdataontheradiationcontentofrawfoodproducts.TheresultwouldreassurenorthernMarshallIslandsresidentsaboutoneofthepossibleingestionpathwaysofplutoniumandstrengthenthecaseformultipleusesoftheUjelangdietmodel.

IfresidentsofRongelapagreeonareasonablegoalforindigenous-foodintake,theUjelangdietmodelwillbesufficientforscenario-basedcalculationsofdose.

4.MeasurementsonHumansThemeasurementofthekind,quantity,location,andretentionofradionuclidesinthebody(oftencalledbioassay)isaccomplishedeitherbydirectmeansorbyindirectmeans.Withdirect,orinvivo,bioassay,aradiationdetector(orsystemofdetectors)outsidethebodyisusedasawhole-bodyorpartial-bodycountertoidentifyandestimatethebodyburdenororganburdensofradionuclides.Thismethodcanbeusedforradionuclidesthatemitradiationthatissufficientlypenetratingtobedetectedoutsidethebody,suchaspenetratinggammaraysassociatedwithcesium-137,potassium-40andcobalt-60.Indirect,orinvitro,methodsinvolvethecollectionandanalysisofsamplesthatareexcreted,secreted,orremovedfromthebody(suchasurine,feces,breath,hair,andperspiration)andinferthebodyburdenororganburdensthroughuseofametabolicmodel.Invitromethods,commonlyurinalysis,mustbeusedforradionuclideswhoseemissionscannotbereadilydetectedoutsidethebody,suchasplutoniumandstrontium.

BioassaymeasurementshavebothhistoricalandprospectiverelevancetotheMarshallIslandssituation.Historicalmeasurementsprovideinformationontheuptakeofradionuclidesfrompasthabitationontheislands,providedataonthemetabolicbehavioroftherelevantradionuclidesinthesepopulations,andprovideabasisfortestingmodelsthatareusedtoestimateintakeandradionuclideburdensfromenvironmentaldata.Acontemporarybioassayprogramwouldestablishpre-resettlementbaselinesonthepeopleexpectingtoreturntoRongelap.AbioassayprogramfortheRongelappeopleafterresettlementwillprovideameansfortrackingdosefromfutureradionuclideintake.

BioassaymeasurementsonRongelapresidentshavebeenperformedbyBNLpersonnelaspartofamedicalexaminationprogramafterthenuclear-testseriesinthePacific(Lessardetal.,1984;Miltenbergeretal.,1980;Sunetal.,1992b).Whole-bodycounting,withemphasisoncesium-137,hasbeenconductedsince1958.FromthestudiesconductedbyBNLduringtheRongelapresettlementfrom1957to1985thewhole-bodymeasurementswereinstrumentalinprovidinginformationonthebuild-upofradionuclideburdens.Forthefirstfewyearsafterresettlementthebody-burdensofcesium-137andstrontium-90increased,reachedanequilibriumwiththeenvironment,andthenbeganagradualdecline.Thebody-burdensofcesium-137werefoundtoreachtheirpeakin1965atabout23%ofthemaximumpermissiblelifetimevaluesforworldpopulations(Conard,1992).Intheearly1980s,BNLbeganinvestigatingurine-bioassaymethodssuitablefordetectingplutonium-239and240intheMarshallese.EarlyattemptsusingaPhotonElectronRejectionAlphaParticleLiquidScintillation(PERALS)techniquewereunsuccessfulowingtohighreadingscontributedfromnaturallyoccurringconcentrationsofpolonium-210.Thesefindingspromptedthedevelopmentofthefissiontrackanalysis(FTA)methodtoobtainbettersensitivitybyremovingthepoloniuminterference.UnfortunatelytheearlyPERALSandFTAresults,whichwerereleasedwithoutadequateQA,mayhavecontributedtothepeopleofRongelapdecidingtoleavetheir

homelandforMejattoin1985(Sunetal.,1992c).

Whole-bodyCounting

ReviewofActivities

Detailedinformationonthewhole-bodycounting(WBC)system,itsuse,andtheassociatedquality-assurance(QA)programwasgiventoallmembersofthecommitteeinanotebookentitledOperatingandQAProceduresDocumentsfortheRadiologicalDoseAssessmentProject.Inaddition,thecurrentMarshallIslandRadiologicalSafetyProgramatBNLwasreviewedbyseveralmembersofthiscommitteeduringasitevisitonMay28,1992.ThatvisitprovidedtheopportunitytoreviewmuchofthismaterialandtoseeanoperatingWBCsystemsimilartothetwocurrentlyusedontheship,OffshoreVenture,duringsamplingtripstotheMarshallIslands.

ThecommitteewasalsoprovidedcopiesofareportdatedApril23,1990,preparedbyanindependentBNLscientificreviewcommittee.ThereportwasattachedtoaletterdatedMay2,1990,fromRoscoeL.Hall,chairmanofthereviewcommittee,toWalterKato,chairmanoftheBNLDepartmentofNuclearEnergy.Thereviewcommitteereportedthat"thewhole-bodycountingproceduresusedforestimatingtotalbodyburdensofcesium-137,potassium-40andcobalt-60werewithinacceptableguidelinesoftechnicalexcellenceandconformedtorecognizedstandardssetformakingaccuratemeasurementsoftheseradionuclidesinvivo."

RecentbioassaymissionstotheMarshallIslandswereconductedduringJuly1989,February1991,andJune1992.Thegeneralapproachduringthosemissionswastomeasurebaselinecesium-137bodyburdensinpopulationsfromEnewetok,Rongelap,andUtirikAtolls.Table4-1showsthenumbersofpersons(volunteers)thatwerecountedwhowereresidents,orformerresidents,ofthoselocations

duringthe1989and1991missionsandthepopulationaveragedoseratesfromingestedcesium-137basedonthosemeasurements;theuncertaintiesindosesshownas1standarddeviation(L.C.Sun,Personalcommunication,1994)Eachpersonwascountedfor15min.Becausetwodifferentchair-orientedcountingsystemswereused,partoftheQAprograminvolvedrecountsofsomepersonsinthesamechairandcross-countsofsomepersonsinbothchairs.Therewasnostatisticallysignificantdifferencebetweenoriginalcountsandrecountsatthe97%confidencelevelorbetweenoriginalcountsandcross-countsatthe99%confidencelevel;hence,theprecisionobtainedinthesemeasurementswasjudgedtobehigh.

OnthebasisofinformationprovidedonthecountingandstandardizingproceduresandontheQAprogram,thecommitteebelievesthattheprogramistechnicallysoundandcapableofproducingconsistent,reproducible,andhigh-qualityWBCmeasurementsofMarshallIslandresidents.Twoaspectsofdose-assessmentstrategythatwillneedtobeaddressedarewhoshouldbecountedandhowoftencountsshouldbemade.TheMOUfortheRongelapResettlementProjectbearsdirectlyonthoseaspects.Aprimaryconditionfordeterminationtoinitiateresettlementis(ArticleII,Section2)"thatthecalculatedmaximumwhole-bodyradiationdoseequivalenttothemaximallyexposedresidentshallnotexceed100millirem(mrem)/yearabovenaturalbackground,baseduponalocalfoodonlydiet."Also,theMOU

Table4-1.NumbersofPersonsResidentsandFormerResidentsofSeveralLocationsWhoVolunteeredforWhole-BodyCountingandthePopulationAveragesofCesium-137AnnualDoseRatesDetermineda

NumberPersonsCounted

Cesium-137PopulationAverageAnnualDoseRateb

1989 1991 1989 1991

Enewetok 216 311 11±3(1.1±0.3) 22±4(2.2±0.4)

Rongelap(Mejatto)

258 427 3±2(0.3±0.2) 2±2(0.2±0.2)

Utirik 414 272 39±2(3.9±0.2) 35±3(3.5±0.3)

Others 28 41

Totals 916 1,051

aDatapresentedinanunpublishedBrookhavenNationalLaboratoryinternalreport(Sunetal.,1992c);basedonmeasuredWBCdistributionmediansfromcesium-137.

bDoseratesexpressedinunitsofmSv/y(mrem/y);uncertaintiesare1standarddeviation.

states(ArticleII,Section11)that''theparties...recognizetheneedforcontinualradiologicalmonitoringbothofreturnedcitizensandoftheRongelapAtollenvironmentuponresettlement."Aswillbeseenlater,cesium-137willcontinuetobethemajorcontributortodose;thereforeWBCshouldbetheprimarymeansofprovidingcontinuedradiologicalmonitoring.

TheemphasisoftheBNLprogramhasbeenonpopulation-relatedvalues.However,withtheemphasisgiventhemaximallyexposed

residentintheMOU,changesinthefuturedirectionoftheWBCprogrammightberequired.ItappearsthattheBNLprogram,hassofaremphasizedhowmanypeopletocount,ratherthanwhomtocountandhowoftentocountthem.Therehasbeennoplantofollowadefinedgroupofindividualswithprescribedcharacteristicsofagedistribution,lifestyle,ordiet;instead,onlyvolunteershavebeencounted.Becausethemakeupofthevolunteergrouphasbeendifferentineachsamplingtrip,itisdifficulttointerpretincreasesordecreasesinaveragecesium-137bodyburdensmeasuredinthesampledpopulationfromonesamplingtriptoanotherandit'sparticularlydifficulttoobtainandmaintainindividualrecordsthatwillbeneededtoevaluatefuturetrends.

TheBNLstaffhasconsideredanefforttolocaterecordsforpersonswhohaveundergonemultiplewhole-bodycounts.Althoughthiseffortmightprovidesomeadditionalinformation,thelongtimebetweencountsisacriticalshortcoming.AllWBCisnowcurrentlydoneontheshipOffshoreVentureandcanbedoneonlywhentheshipisavailableforBNLuse.Otherorganizations,suchasLLNL,usetheship,andseasonalweatherconditionsalsoaffecttheschedule.AccordingtoBNLpersonnel,planscallforonesamplingtripperyearandhalftheplannedsurveydoneeachyear,forinstance,RongelapandUtirikissampledoneyearand

EnewetokandBikini(Kili)thenextyear.Onthisschedule,theRongelappeoplewillbecountedevery2y;thisisaninappropriateschedulefortryingtofollowpossibleintakesofcesium-137whichhasaneffectivebiologicalhalf-timeofabout100d.

Recommendations

TheCommitteeoffersthefollowingrecommendationsfortheWBCprogram:

Untilexperiencedictatesotherwise,theprogramshouldensurethateverymemberoftheresettledpopulationreceivesawhole-bodycountannually.ThiswillaidinprovidingassurancethattheconditionsoftheMOUarebeingmetbydeterminingactualbodyburdensandtherebyprovidingthedatanecessarytoevaluatethedosetothemaximallyexposedresident.

AdopttheapproachoffollowingadefinedRongelapsubpopulationduringdifferentseasonstoobtainabettertemporaldefinitionofcesium-137uptakeandlossbeforeandafterresettlement.

SummarizethedataonpersonswhohaveparticipatedinthehistoricalWBCprogramoverthelongterm.Thiswillaidinidentifyingacorestudygroupforthefuture.Itwouldalsoprovideinsightintotheinitialrapidincreaseobservedincesium-137bodyburdensinthe"averageadult"from11nCiin1957to730nCiin1958andtheincreasefrom170to280nCiduring1979-1982.

Developthefacilitiesorlogisticalcapabilityforregular,morefrequentcountingofthestudygroup.Therearetwopossibleapproaches.OnewouldbetouseanothershipthatcouldbededicatedmostofthetimetoWBCactivities;thisoptionmightnotbefeasible,becauseofthesubstantialcostsinvolved.AnotherapproachistoestablishfacilitiesatselectedlocationssothatWBCinstrumentationcouldbequicklyinstalled,used,andmovedtothenextlocation;this

optionseemspossibleonthebasisofexperienceinmaintainingWBCfacilitiesinremoteareas(Hanson,1982;Hansonetal.,1964),althoughsomelogisticalaspectswouldhavetobeaddressed,includingstaffing,electricalpower,water,airconditioning;andcontinuedparticipationofthestudygroup.Centralized,land-basedWBCfacilitiesonthreeatollsintheMarshallIslands(orhowevermanylocationsaredeemednecessaryfortheDOEmission)wouldhaveseveraladvantagesoverthecurrentship-basedpractice:weatherconditionswouldbelessconstraining,moreadultswouldbeavailablewithoutthe24-hconfinementtotheshipnowrequired,samplingcouldincludemorefrequentrecountsofpeople(asrecommendedabove);andgreatermobilityandflexibilityofWBCcapabilitycouldbeintegratedwithdietaryandlifestylephenomenatoprovidemeasurementsatcriticaltimesindicatedbythatinformation.

GivegreaterrepresentationtoadolescentfemalesintheWBCprogram.In1983doseratescalculatedforcesium-137inyoungfemales(59mrem/y)werenearlytwicethosecalculatedforadultmalesandfemales(32mrem/y).Adolescentfemaleshadcesium-137body

burdensexceedingthoseofbothadultmalesandadultfemalesduringthemeasurementyears1981-1984and1989.

UrinalysisforPlutonium

AccordingtothedosimetryestimatesmadebyRobisonetal.(1993),theprimarycontributorstotheannualeffectiveradiationdoseforpersonsonRongelapIslandwouldbetheexternaldosefromcesium-137inthesoilandtheinternaldosefromcesium-137infood.Together,thosetwosourcesaccountforabout95%oftheannualradiationdose.Theinhalationandingestionofplutonium-239andplutonium-240accountforabout1%ofthecalculatedannualeffectivedose,asdoestheinhalationandingestionofamericium-241.

Althoughplutonium-239andplutonium-240areexpectedtobeminorcontributorstotheannualeffectiveradiationdose,plutoniumisaconcernoftheRongelappeopleandsoilconcentrationlimitsareincludedintheMOU.Alogicalfollow-uptoassurethelimitsarenotexceededistodeterminetheextenttowhichplutonium-239andplutonium-240havebeendepositedinthebodiesofRongelapresidentsafterresettlementandverifythatplutonium-239andplutonium-240areinfactminorcontributorstodose.

Asdiscussedabove,WBCisausefultoolformeasuringinternalburdensofradionuclidesthatemitradiations,x-andg-rays,thatcanescapefromthebodyandbemeasuredbyexternaldetectors.However,WBCisnotusefulformeasuringlow-levelinternaldepositionofalpha-emittingradionuclidessuchasplutonium-239andplutonium-240becauseoftheveryshortrangeoftheemittedalpharadiation(about40mminunit-densitytissue).Therefore,aninvitrobioassaytest,suchasurinalysis,isgenerallyusedtodetectandestimatethemagnitudeofinternaldepositionofplutoniumandotheralpha-emittingradionuclides.Theusefulnessofurinalysisfor

assessingpossibleuptakesofplutoniumafterresettlementdependsontheexpectedmagnitudeofinternaldeposition,thefractionoftheinternalburdenexcretedperday,thesensitivityoftheanalyticalradiochemicalmethodused,andotherfactors.

UrinaryexcretionofplutoniumbyresettledRongelappersonswillconsistofabaselinelong-termexcretionfromanyresidualsystemicburdensacquiredfrompreviousexposure,abaselinecomponentconsistingofpromptandlong-termexcretionfromthegeneralworldwideenvironmentalcontamination,andthepotentialprompt-excretioncomponent(plus,eventually,thelong-termexcretion)fromanyintakeassociatedwithresettlemet.Pertinentquestionsregardinglongtermfollow-upofapopulationthathaspotentialforingestionofplutoniumthenarethese:Whatistheexpectedbaselineexcretionforthesepeople?Whatnewcontributionislikelytobeexpectedfromlocalsources,andcanitbedetectedinthepresenceofthepreexistingcomponent?Whatexcretioncorrespondstoa"significant"incrementofintake,andcanitbedetectedinthepresenceofthepreexistingcomponent?

SensitivityRequirements

Whenabsorbedfromthegastrointestinaltractafteringestionorfromtherespiratorytractafterinhalation,plutoniumentersthebloodandisdepositedprimarilyintheliverandskeletonwhereitisretainedforbiologicalhalf-livesof20and50y,respectively.Asmallfraction(about1%)oftheamountthatentersthebloodisexcretedintheurineduringthefirstdayafter

absorption.Laterurinaryexcretionofplutoniumfromthisabsorptiondecreasesrapidlybecauseoftheprolongedretentionofplutoniumintheliverandskeleton,eventuallyapproachingexcretionofabout2x10-5ofthesystemicburdenperday.Knowledgeoftheseratesisimportantwheninterpretingtheanalyticalresultsforplutoniuminurine.

Becauseofworldwidefalloutofplutoniumduetoatmospherictestingofnuclearweapons,itislikelythatresidentsofthenorthernhemispherehavesufficientsystemicburdensofplutoniumtoproducedailyurinaryplutoniumexcretionratesofaround2-4mBq(54-108aCi;aCi=attocurie=10-15Ci)(Boeckeretal.,1991).TheurinaryexcretionofplutoniumbyMarshallIslandsresidentshasbeenmeasuredrecentlywithaverysensitivefission-trackanalyticaltechniquethatisclaimedtodetectplutonium-239concentrationsaslowas2mBq(54aCi)per24-hurinesample(Sunetal.,1992b;Sun,privatecommunication,BNLbriefing,1992).Intheirestimates,Sunetal.assumeanexcretionof1-2mBq(27-54aCi)per24-hurinesamplefromadultsasaresultofglobalweaponsfallout.Ofthe67Rongelapurinesamplesassayedin1989,16wereabove2mBq(54aCi)fora24-hsample;thehighestwas6mBq(162aCi).Valuesofthismagnitudearethebackgroundlevelsagainstwhichtheresultsoffutureurinalysismustbedistinguishedtofollowanypossiblefutureuptakesofplutoniumafterresettlement.

Afterresettlement,exposuresmightoccurasaresultofingestionofplutoniuminfoodorsoilorinhalationofplutoniumresuspendedintoairfromthesoil.Suchexposureswouldbeexpectedtobeprimarilylow-level,chronicexposures.TwoapproachescanbeconsideredforanalysisofplutoniuminRongelapresidentsexposedundertheseconditions:theverysensitivefission-trackprocessnowbeingusedbyBNLstaffandthemuchlesssensitivealphaspectrometricprocesscurrentlyusedtodetectandassesspossibleoccupationalexposuresto

plutonium.

Considerableday-to-dayfluctuationsoccurinurinaryexcretionofplutoniumandthesefluctuationsinthebackgroundexcretionratescaninterferewiththedetectionofaverysmallincreasesinthelevelinplutoniumduetochronicintakesafterresettlement.Forpurposesofdiscussion,assumethaturinaryexcretionmustincreaseby4mBq(108aCi)forittobedetectedabovetheexistingbackgroundexcretionlevel.Withthelong-termurinaryexcretionfactorof2x10-5ofthesystemicburdenperday,suchanexcretionwouldcorrespondtoasystemicplutoniumburdenofabout0.2Bq(5.4pCi).Withanapproximatedose-conversionfactorof27mSvofannualeffectivedosefrom1Bqofsystemicallydepositedplutonium(0.1mrem/pCi),asystemicburdenof0.2Bq(5.4pCi)wouldresultinanannualeffectivedoseof5mSv(0.5mrem).Thoseconditionssuggestthatthefission-trackanalyticalprocesscouldbeusedforlong-termurinalysistofollowthepossiblesystemicdepositionofplutoniumfromlow-levelchronicexposuresthatwouldcontributeasmallfractiontothetotaldoselikelyfromradionuclidecontamination.

Ifthefission-trackanalyticalmethodisusedforthatpurpose,itisimportanttounderstandpossibleproblemswithitsuse.Itisstillanewmethodwithwhichlittleoperationalexperienceisavailableasdescribedlater.Themethodisextremelysensitive,andfluctuationsintheobserveddailyexcretionratecanbequitelargeforavarietyofreasonsincludingtemporarilylargerexcretionsfromveryrecentintakes.Thesefluctuationscouldbemisleadingininterpretation.

Asanalternateapproach,onemightconsidertheuseofthealpha-spectrometrymethod.

However,thedetectionsensitivityisabout1/40thatofthefissiontrackmethod,andtheminimumdetectablesystemicburdenwouldbeabout7Bq(189pCi).Suchaninternalburdenofplutoniumwouldresultinanannualeffectivedoseofabout0.2mSv(20mrem),or1/5theannuallimitspecifiedintheMOU.Thismethod,therefore,isinsufficientlysensitiveanddoesnotprovideausefulalternativetothemoresensitivefission-trackanalyticalprocess.

ReviewofActivities

AprogramofurinalysisoftheMarshallese,inadditiontotheWBCprogram,isbeingconductedbyBNL.Inthiscommittee'sreviewofBNLactivities,itobservedproblemsinthemethods,partlybecauseoftheattocurie-levelsensitivitytheyareattemptingtoachieve(Moorthyetal.,1992).Becausetherateofexcretionofsystemicplutoniumissosmall,theprocedureforitsanalysismusthavehighsensitivity.TheBNLprocedure,whichisbasedonfission-trackcounting,consistsofmanystepsandisverytime-consuming.Toavoidcontaminationbyuranium,whose235isotopeproducesfissiontracksthatwouldbeinterpretedasbeingcausedbyplutonium,elaboratereagent-purificationandcontainer-cleaningproceduresarenecessary.Separationandpurificationofplutoniumareaccomplishedbyanionexchange.Becauseofgreatchangesinvolumesandconcentrationsofthesolutions,twoanion-exchangestepsareused,thesecondwithdistilledacidsandcarefullywashedcontainerstoexcludeuranium.Thepurifiedplutoniumfractionsaremountedonquartzslidesthathavebeenexhaustivelywashed,andtheyaresenttoareactorforneutronirradiation,afterwhichthenumberoffissiontracksoneachslideiscarefullydetermined.Theresultsareusedtocalculatetheamountofplutonium-239present.Thesensitivityofthemethodisestimatedtobearound2mBq(54aCi).

Asanticipated,thecomplexnatureoftheplutoniumanalysisresulted

inthedevelopmentofanextensiveradioanalyticprocedure.DuringthereviewoftheproceduresuppliedtocommitteemembersasaBNLinternalreporttherewereanumberofquestionsraised.ThedocumentedBNLproceduresgiventhecommitteecontainederrorsthatcouldleadtoimproperchemicaloperationsthatcouldinvalidatethefinalresults,anditdidnot,insomesteps,describewhatisactuallydone.Forexample,intwocasestherewasconfusionbetweennitrateandnitriteions,onebeingspecifiedwhentheotherisrequired.Sodiumnitriteisusedtoconvertallplutoniumtothetetravalentstatesothatitwillsorbonananion-exchangecolumn;ifsodiumnitratewereusedinstead,someoftheplutoniumwouldnotbeconvertedandwouldpassthroughtheanion-exchangecolumnunsorbed,leadingtoalowvalueforthefinalplutoniumcontent.Plutoniumisalsosubjecttohydrolysisthatformscolloidalspeciesthattendtosorbontocontainerwalls,buttherearewaystopreventthis,suchaskeepingsolutionpHlowandusingTefloncontainers.Atonepoint,theBNLprocedurecalledfordilutionwithwater,whichcancauselocalizedareasofhighpHthatcanleadtohydrolysis;diluteacidshouldbeusedforthisdilution.Containersaresaidtobeexhaustivelywashedtoremoveuraniumcontamination,buttheyarenotspecifiedasmadeofTeflon.Theneedtoexcludeuraniumisindeedimportant,butequallysoistheneedtoavoidplutoniumlossbysorption.Thesepossiblycontradictoryrequirementsmightrequireacompromise,butatleastthefactorsinfluencingthechoiceofanoptimumcontainershouldbeaddressed.

Theconditionsleadingtoplutoniumretentionbythecontainerarenotlimitedto

hydrolysis.Evaporatingaplutoniumsolutioneveninconcentratedacidtototaldrynesscancausetheresiduetobecomeoverheatedandbakeontothecontainerbottom;completeredissolutionisthendifficult.Despitethatproblem,theBNLprocedureprovidedinaninternalreportcalledforevaporationtodryness.Anotherquestionthatneedsfurtherverificationiswhetherthehighercontentofplutonium-240infalloutthaninweapons-gradeplutonium,hasbeentakenintoaccountinthecalculations.Althoughtherehavebeeninformalassurancesthatthiscorrectionhasbeenmade,thematterneedsfurtherdocumentation.

TheBNLrecipeforsyntheticurineprovidedtotheCommitteeincludescreatineinsteadofcreatinine,eventhoughthelatteristhenormalcomponentofurine.InconversationswithBNLstaff,itwasindicatedthattheywerecurrentlyusingneither.Theomissionisimportantbecausecreatinine,apotentialcomplexingagent,couldhaveasignificanteffectonthebehaviorofplutonium.WhenthecommitteediscussedtheshortcomingscitedabovewithBNLpersonnel,theystatedthattheywerenotadheringstrictlytotheprocedureprovided,thattheprocedurewasbeingupdated,andthatthecommittee'sconcernswereunwarranted.ThenewprocedurewasunderdevelopmentandwasexpectedtobeimplementedinJune1993.InFebruary1994,thecommitteewasprovidedapreliminarydraftofanupdatedversionofthechemicalprocedures(Kaplan,personalcommunication,1994).The''marked-up"draftproceduressuggestthatmanyofthepointsraisedinthecritiqueoftheoriginalprocedureshavebeenrecognized.Whetherapplicationofthenewproceduresiseminentis,however,unknown.Itisimportantthatthenewproceduresbeproperlyreviewedanddocumentedpriortotheirbeingimplementedintheroutinelaboratorysetting.Theprimaryrecommendationofthecommitteeisthat,inananalyticprocedureascomplexasthatusedintheanalysisoftracequantitiesofplutoniumin

urine,theremustbecarefuloversight,review,andtestingtoassureoptimumprecisionandaccuracyoftheassay.Effortsshouldalsobeintensifiedtodevelopalternativetechniques,suchasmassspectroscopy,thatmayhavethenecessarysensitivity,butahigherdegreeofaccuracyandprecision.

TheQAprogram,underwhichtheplutoniumanalyseswereconductedbyBNLpersonnelconsistedalmostentirelyoftheuseofin-house-preparedblindsamplesinsyntheticurine.Thisprogramneedsimprovement.Aspartofthisprogram,sampleexchangewasinstitutedwiththeUniversityofUtah(Singh,personalcommunication,1993),butapparentlyonlytwosampleshavebeenrunbybothlaboratoriestodate.Theresultsonthetwosampleswereencouraging:thetwolaboratories'valuesagreedtowithin25%inbothcases,withonelaboratoryreportingahighervalueforonesampleandtheotherahighervaluefortheothersample.Nevertheless,twosamplesconstitutefartoosmallapopulationfromwhichtodrawameaningfulconclusion.Moreexchangesampleswerenotrun,becauseoflackofadequatefundingatthattime,butitwasstatedthatanadditionalfourexchangesamplesareplanned.Resultsoftheseexchanges,iftheyhavetakenplace,havenotbeenavailabletothiscommittee.Inanycase,additionalsampleexchangesarenecessarybeforethevalidityoftheBNLprocedurecanbeproperlyassessed.TheUniversityofUtahisagoodchoiceforthissampleexchange,becauseitsprocedureissubstantiallydifferentfromtheBNLprocedure,specificallyintheuseofafront-endprecipitationwithrhodizonicacidforpreliminaryseparationofplutonium,theuseofhydrochloricacidratherthannitricacidsolutionsintheanion-exchangesteps,andtheuseofpolycarbonateratherthanquartzslidestomountthesamplesforneutron-irradiation.TheclaimedsensitivityoftheUtahprocedureisabout1.5mBq(40aCi).

ConclusionsandRecommendations

Formeasurementofplutoniuminurine,toensurethatplutoniumremainsanegligiblecontributiontodose,anextremelysensitivemethodwillberequiredtodetectlikelyintakes.Thefission-trackmethodcurrentlybeingused(andapparentlyundergoingfurtherrefinement)appearstohavesufficientsensitivitytoprovidetheneededassurances,butitsaccuracyandprecisionispresentlyunproven.Carefulattentionisneededtoensurethatproblemsinherentinthechemical-separationproceduresandintheurine-collectionprotocolareresolvedandunderstood.Thecommitteefeelsthatanactiveprogramofinterlaboratorycomparisonshouldbeundertakentodocumenttheaccuracyandprecisionofthetechniquesbeingimplementedforroutineplutoniumanalysis.Inaddition,problemsencounteredininterpretingmeasurementsofplutoniuminurineneedtobecarefullydocumentedandunderstoodbeforeanyprogramisinitiatedforroutinemonitoringofplutoniumintake.

5.DosimetryandItsApplicationAsstatedearlier,radiationdoseattributabletofalloutcontaminationofRongelapAtollresultsfromexternalexposurefromgamma-emittingradionuclidesdistributedthroughtheenvironmentandfrominternalexposureduetotheintakeofradionuclidesthroughinhalation,ingestion,andabsorptionthroughtheskin.Owingtothenaturalprocessesofweatheringandthedecayofmanyelementswithshorthalf-livesonlyfiveoftheradionuclidesoriginallydepositedonRongelapasaconsequenceoftheBRAVOtestarestillpresentinsufficientquantitiestocontributesignificantlytotheestimateddosetoindividualswhomayreturntoliveonRongelap(KercherandRobison,1993).Theseare:cesium-137,strontium-90,plutonium-239,plutonium-240,andamericium-241.Oftheseradionuclides,cesium-137accountsformorethan90%oftheprojectedradiationdose.

Potentialradiationdosesfromexposuretoexternalradiationcanbepredicteddirectlyfrommeasurementsoftheradiationfield.Predictionofradiationdosesfrominternalsourcesismorecomplicated.Whenradioactivematerialistakeninbyinhalationoringestionorispresentedtotheskin,afractionisabsorbedandreachesthebloodstream.Theabsorbedmaterialisthendistributedtovariousorgansandtissues.Theradioactivityiseventuallyremovedfromthefluids,organs,andtissuesbyradioactivedecayandbybiologicalprocesses.Thefractionabsorbed,thedistributionafterabsorption,andtheratesandpathwaysofradionuclidemetabolismaredeterminedbytheelementsandchemicalforms.

Indosescalculatedprospectively,intakeofeachradionuclideisestimatedastheproductofitsconcentrationinair,food,water,or

othermediumandthequantityofsuchmediumtakenintothebodythroughbreathing,ingestion,orskinabsorption.Theabsorption(uptake),distribution,andretentionofaradionuclideisestimatedfrombiokineticmodelsoftheelementinhumans.Radiationdoseratestovariousorgansandtissuesarethencalculatedfromthecharacteristicsoftheradiationandphysicaldosimetricmodelsofthetransportandabsorptionoftheradiationinthehumanbody.Cumulative(time-integrated)dosescanbecalculatedfromtheexpectedresidencetimeoftheradionuclideinthebody.

Afterasingleintake,thequantitiesofradioactivityinindividualorgans(organburdens)andthewholebody(bodyburden),andhencetheassociatedradiationdoserates,rapidlyreachamaximumandthendecreasebecauseofradioactivedecayandbiologicalelimination.Inthecaseofcontinuous,chronicexposure,organandbodyburdenscontinuetobuildupuntilamaximumisreachedatwhichtheincreaseisbalancedbytheloss.Theburdens(andassociateddoses)thenfollowtheconcentrationsintherelevantenvironmentalmedia.Thetimetoreachthismaximumvarieswiththeradionuclideanditschemicalform.Themaximumoccursearlierforradionuclideswithshorteffectivehalf-lives(asdeterminedbyradioactivedecayandbiologicalretentiontime).Itoccurslaterforradionuclideswithlongeffectivehalf-lives.Forexample,cesium-137hasaneffectivehalf-lifeofabout100dintheadulthuman;underconstant(orslowlydecreasing)continuouschronicintake,themaximumdoseratecan

beexpectedtooccurwithinabout2years.Incontrast,aportionoftheplutoniuminthehumanbodyhasaneffectivehalf-lifeofaround50y,andundercontinuouschronicintake,thebodyburden(andassociateddoserates)wouldbeexpectedtoincreasethroughoutthelifetimeofaperson.

Forthepurposesofradiationprotection,radiationdoseisexpressedintermsofequivalentdose,which,foragiventypeofradiation,istheproductoftheenergydeposited(absorbeddose)andtheeffectivenessofthetypeofradiation(radiationweightingfactor).Dosesresultingfromnonuniformspatialdistributioninthebody,asoccurswiththeselectivedepositionofradionuclidesinvariousorgansortissues,canbeexpressedintermsofeffectivedose,asummationoforgandosesinamannercalculatedtobebiologicallyequivalenttothedosefromauniformwhole-bodyexposure.Effectivedoseiscalculatedbymultiplyingtheindividualtissueequivalentdosesbyspecifictissueweightingfactorsandsummingtheweightedtissuedoses.

Onceradionuclidesenteraperson'sbody,thepersonis"committed"tothedoseresultingfromtheradioactivedecayoftheradionuclidesforaslongastheyremaininthebody.Forassessingradionuclideintakesbymembersofthepublic,theInternationalCommissiononRadiologicalProtection(ICRP)Report56(ICRP,1989)recommendscalculatingcommitteddosesfromthetimeofintaketoage70.Incontemporaryterminology,thedosecommitmentsfromanintakeareexpressedintermsofthecommittedequivalentdosetoorgansandtissuesandcommittedeffectivedosetothewholebody.Forthepurposesofdoselimitation,thecommitteddose(for50yinadultsandtoage70forchildren)fromtheannualintakeofradionuclidesisconsideredpartofthatyear'sradiationdose(ICRP,1991a).

Intheinternationalsystem(SI)ofunits,equivalentdose,effectivedose,committedequivalentdose,andcommittedeffectivedoseare

expressedinsieverts(Sv).BeforeadoptionofSIunits,theunitofdoseinthetraditionalsystemwastherem(1rem=0.01Sv).

Reconstructionofpastradiationdosesandpredictionoffuturedosesalsoinvolvesknowledge,orprediction,ofthetime-dependentnatureoftheexposurepattern.Incircumstanceswherenocontinuousindividualrecordofexternalexposureorradionuclideintakeisavailable,theexposurepatternmustbemodeled.Afrequentlyusedapproachtoestimatingexposureistodevelopscenariosfordifferentexposurepatterns,whichinturnmightincludedifferentestimatesofintake.Thescenariosmightbefora"reasonable"exposure,a"maximum"exposure,oranyotherdesiredsituation.Althoughitisdifficulttoverifyanyindividualscenario,reasonableboundaryconditionsforexposurecanbeestablishedifseveralaredeveloped.

DosimetryApproaches

ExternalDose

Thedoseratefromexternalradiationisreadilymeasurable.Instrumentscanidentifythetype,energy,andintensityofradiation.Fromthesemeasurements,theradiationdosestotissuesandorganscanbecalculated.Alternatively,doseratescanbecalculatedfromthemeasuredorprojectedconcentrationsofradionuclidesinairorsoil.Dose-ratecoefficientsforthesequantitiesarecitedinFederalGuidanceReport12(EPA,1993),butage-specific

coefficientsarenotgiven.

InternalDose

Asnotedearlier,environmentaldata,physiological-anatomicaldata,andelement-specificbiokineticcomputermodelscanbeusedtoestimatebodyburdenandradiationdoseatanytimeafteranintake.Theseelement-specificmodelsareusedtoestimatetissueburdensandassociateddoseratesafteringestionand(whencombinedwitharespiratorytractdosimetrymodel)inhalationofradionuclides.Thebiokineticmodelscanalsobecoupledtointakethroughtheskintoestimateorganburdensanddoserates.

Manymodelshavebeendevelopedtoestimatethemetabolismofelements.ThemostgenerallyapplicablefordosimetryarethosedevelopedbytheICRP.TheICRPbiokineticmodelshaveevolvedfromthesimpleretentionmodelsofICRP-2(ICRP,1959)throughthemorecomplexretentionmodelsinICRP-30(ICRP,1982,1988)andtomodelsthatincludeage-specificabsorptionandorgantransfercoefficients,asexemplifiedinICRP-56(ICRP,1989).

IntakebyInhalationandIngestion

Theintakefrominhaledradionuclidescanbeestimatedfrommeasurementsofbodyburdensorfromprojectionsofradionuclideconcentrationsinair.Measurementsofintakeorprojectionsbasedonradionuclideconcentrationsintheair,water,andsoilareusedasthebasisforcalculatingradiationdosefromingestedradionuclides.Forconvenience,ICRPhaspublishedtheresultsofbiokineticmodels,for"reference"persons,forradionuclideuptakeandretentionbythevarioustissues,factorsrelatingorganburdenstodoseratesinvarioustargettissues,anddosecoefficientsforconvertinginhalationandingestionintakestocommitteddosesinICRP-30(ICRP,1982,1988).Age-specificbiokineticanddosimetricmodelsweredevelopedlater.

Calculationsforselectedradionuclideswereperformedandinhalationandingestiondosecoefficients(committeddoseperunitintake)forgenericpersonsage3mo,1y,5y,10y,and15yoldandadultswerepublishedinICRP-56(ICRP,1989).Thedosecoefficients,althoughdevelopedforgenericmodels,provideaconsistentsetofcalculationsandarerecommendedforcomparisonpurposes.Estimatesoftheradiationdosetotheuterusandtheembryoorfetusfromintakeofradionuclidesfornewexposuresandforpre-existingconditionshavebeenpublishedasNUREG/CR-5631(Sikovetal.,1992;SikovandHui,1993)

IntakeThroughtheSkin

Intakethroughtheskincanbeeitherthroughtheintactskinorthroughwounds.OfparticularinterestintheMarshallIslandsresettlementisthepotentialforuptakefromcontaminatedsoil.Uptakethroughintactskincanbeestimatedfromskincontamination(expectedtobeafunctionofskinsurfaceareaandskinadherenceofcontaminants)anduptakefractions(EPA,1989).Forchronicexposuretocontaminatedsoil,skincontaminationforanindividualofagepcanbeestimatedfrom

whereScistotal-bodyskincontaminationinBq,CsisconcentrationinsoilinBq/kg,Saisskinadherenceofsoilinkg/m2andApisage-specificskinareainm2.Dailyuptake,Du,intheequilibrium,chronic-exposuresituationcanthenbeestimatedfrom

whereUfisthedailyuptakefractionandScisdefinedinEq.8above.InthecaseofresettlementofRongelap,thesoilcontaminantofinterestisplutonium.Studiesofplutoniumabsorptionthroughtheskinhaveusuallyusedplutoniumasthenitrateinacidsolution.Reporteduptakefractionsthroughtheskininhumansrangefrom0.0002%/h(4.8x10-5/d)forplutoniumnitratein0.4MHNO3(Langham,1964;Khodyreve,1966)to0.01%/h(2.4x10-3/d)forplutoniumin9%HCl(ICRP,1986).

OakleyandThompson(1956),e.g.ascitedinLangham(1964,pp.565-582),reportedthatuptakeofplutoniumnitratefromwoundsinanimalswas3timesthatthroughintactskin.Overallsystemicabsorptionwaslessthan1%oftheamountapplied.Intheenvironmental-contaminationscenario,thequantityofsoilinwoundswouldbesubstantiallylessthanthequantityadheringtotheoverallskin,souptakefromwoundsshouldnotaddsubstantiallytotheuptakefromskincontamination.

Uptakeofplutoniumfromabrasion-typewoundsshouldbenegligible.Plutonium,particularlyplutoniumoxide,istrappedinthetissueexudateandimmobilizedintheeschar.Theplutoniumwillbeeliminatedwhentheeschardetachesanddropsoff(Langham,1964;Langhametal.1962).

AppraisalofCurrentDOEAssessments

InestimatingdosesandpotentialriskstothepeopleoftheMarshallIslands,metabolicanddosimetricmodelshavebeenusedtocalculatecontributionsfromexternalsourcesandfrominhalationandingestionofradionuclides.LLNLpersonnelhaveusedsomeofthemostcurrentbiokineticmodelswhenestimatingmetabolismanddosimetryforinhaledoringestedradionuclides.Themostrecentre-evaluationofthepotentialdose(Robisonetal.,1993)usesICRP-30(ICRP,1982,1988),ICRP-56(ICRP,1989),and,forsomecases,ICRP-61(ICRP,1991b).Completeanatomicalandbiokineticfactorswerenotexamined,buttwoindicatorsbodyweightandthebiologicalhalf-lifeofcesium-137donotsuggestanyseriousproblemswithapplicationoftheICRPmodelsforexternalandinternaldosimetryfortheMarshallIslandspopulation.

Bodyweight.Robisonetal.(1993)providedataontheweightsofmalesandfemalesfromfouratolls,includingRongelap.Averagevaluesarecomparabletothoseforthereference70-kgmaleand58-kgfemalegiveninICRP-23(ICRP,1975).

Biologicalhalf-life.Robisonetal.,(1993)quoteBNLdataoncesium-137biologicalhalf-lifeinMarshallese(23malesand21females).Thehalf-lifeformales(median,115d;mean,119d)isnotgreatlydifferentfromthe110dgivenforthelong-livedcomponentinICRP-56(ICRP,1989).Ashorterhalf-lifeisreportedforfemales(83d);thisisconsistentwiththediscussionofcesium-137retentioninfemalesgiveninICRP-56.

Thenuclidesofprimaryimportancehavebeencesium-137,strontium-90,plutonium-239,plutonium-240andamericium-241(Robisonetal.,1982,1993;Kohn,1989;RobisonandPhillips,1989).ThosereferencesandotherdocumentsbyLLNLpersonnelhavereportedestimateddosesreceivedbyMarshallIslandspeopleformanyyears.Exceptwhereotherwisenoted,thefollowingdiscussionaddressesthe1993LLNLdoseassessmentforRongelapIsland(Robisonetal.,1993).

ExternalDose

Estimatesofexternaldoseratehavebeenconsistentwhenrepeatedmeasurementshavebeenmade(Kohn,1989,Table5.1).Gamma-rayexposureratesasafunctionoflocationwereestimatedfromanaerialsurveymadein1978andfromindoorandoutdoorgammaspectroscopyconductedin1988.Themajorcurrentcontributorstoexternalgammadosewereidentifiedascesium-137(morethan99%)andcobalt-60andcorrespondingradioactive-decaycorrectionswereapplied.Theannualdoseequivalenttothetypicalresidentoftheislandwasestimatedwithascenarioinvolvingoccupancy-timeweightingfactorsforfourindoorandoutdoorlocationsofdifferentradiationlevels.Aconversionfactorof0.0075sievert/roentgen(Sv/R)wasusedtoconvertmeasuredexposureinairtodoseequivalenttothetestes.Dosesweredecay-correctedfortheprojectedresettlementdateof1995,andannualdosesandaccumulateddoseswerecalculatedfor

eachofthenext70y.Themaximumexternalgamma-raydoseratewasprojectedtobe0.11mSv/y(11mrem/y)in1995;thiswilldecreaseascesium-137continuestodecayandtomigrateintheenvironment.

Thesourceofdataisappropriate,andtheaerial-surveyandground-basedresultsareconsistentwitheachotherwhendecay-correctedtoacommondate.TheoccupancyscenarioforRongelapIslandappearsreasonable;however,becauseofthedifferentdoseratesontheisland,thedosewillbeloweriflesstimeisspentintheisland'sinterior.TheexposureratefromfalloutishigheronmostotherislandsofRongelapAtollthanonRongelapIslanditself(Kohn,1989),soestimatesforexternalgamma-raydoseforthemaximallyexposedresidentshouldincludeconsiderationoftimespentonotherislands.Forthepurposesofprojectingthepost-resettlementdose,itwouldhavebeenmoreappropriateandmoreconsistenttoconvertmeasuredvaluestoeffectivedose,usingfactorssuchaspresentedinICRP-51(ICRP,1987),ratherthandosetothetestes.However,theconversionfactorswouldnotbegreatlydifferentfromthevalueused,andtheresultswouldnotbesignificantlydifferent.Onthebasisofthedatapresented,thedecay-correctedexternalgammadoseof0.11mSv/yfor1995appearsreasonable.Theprojecteddosesforfuturedecadesareprobablyoverestimated,inasmuchasthecorrectionswerebasedonlyonphysicalhalf-lifeoftheradionuclideswithnoconsiderationoftheeffectiveenvironmentalhalf-life.

TheLLNLreportpointsoutthattheexternalbetadosewouldbeashallowdoseonlyand

thatthebetacontributionwouldaddonlyslightlytothegammashallowdose.Itconcludes,consideringtherelativelylowrisk-basedweightingfactorfortheskin,thatthebetacontributiontothetotaleffectivedosewouldbeextremelysmall.ThisappearstobeaReasonableConclusion.

IntakeandInternalDose

Inhalation

Potentialinhalationexposureduetoresuspensionofradionuclide-bearingsoilwasassessed.AirborneradionuclideconcentrationswereprojectedforRongelapfrommeasuredconcentrationsinRongelapsoilandenhancementfactorsdevelopedintheresuspensionexperimentsconductedonotherMarshallIslandsatolls.Becausetheaverageconcentrationsoftransuranicradionuclidesinsurfacesoilsovertheentireislandwereobservedtoberoughlytwicethoseinthevicinityofthevillageandhousingarea,locationwasanimportantvariableinprojectingairborneconcentrationandinhalationintake.InhalationintakeforthetypicalRongelapresidentwasprojectedwithascenarioinvolvingtimeweightingforfouractivity-locationcombinations.

AverageplutoniumandamericiumconcentrationsreportedforRongelapsurfacesoilandtheprojectedaverageannualintakeoftheseradionuclidesarepresentedinTable5-1forthereferenceyear1995.Concentrationsofcesium-137andstrontium-90inthesoilwerealsomeasuredbuttheseradionuclideswerenotincludedintheinhalationdoseassessment;theproductofthesoilconcentrationandtheinhalationdosefactorsforthevariousradionuclidesindicatesthattherelativedosecontributionsofthesetwowillbeordersofmagnitudelessthanthedosecontributionsfromplutoniumandamericium.

ICRPdosemethodsandmodelswereusedtoconvertinhalation

intaketodose.Projectedintakesofplutoniumandamericiumwerepresentedasfractionsoftheintakelimitcorrespondingto1mSv/y(numericallyequivalenttothecommittedeffectivedoseinmillisieverts/yearseeTable5-1).

Fromtheinformationprovided,theresuspensionexperimentsappeartobereasonableandaddanimportantdimensiontothedoseassessment.Thealgorithmforcomputingintakeaccountsfortheimportantfactors.Theoccupancyscenarioisdifficulttoevaluate,buttherearenoobviousproblems.Thebreathingratesandthedistributionbetweenrestingandactivearesimilarto,butnotidenticalwith,thevaluesfortheICRPreferenceadultmale.Thecommittedeffectivedosesareontheorderofascaleofmicrosieverts/year;annualdoseswillinitiallybemuchlowerandwillslowlyapproachthisvalue.

Therewerenoage-dependentcalculations.Althoughtheuseofreference-manbreathingpatternsshouldgiveaconservativeestimateofnonadultintaketheICRPinhalationmodelisthesame(ICRP,1989)anage-dependentscalingofbreathingrateswouldhavegivenabetterapproximation.Comparisonofthe70-yeffectivedosescalculatedforchildrenforplutoniumandamericiumwiththoseforadultsinICRP-56suggeststhatthedoseratesforamericiummightgodownbyafactorofabout2,butthoseforplutoniummightgoupbyafactorof3.Uncertaintiesininhalationdepositionanddosebynuclidewerenotcalculated.

Table5-1Surface-SoilRadioactivity,ProjectedInhalationIntakesandProjectedInhalationDoseofSelectedRadionuclidesa

Plutonium Americium

Soilconcentration Bq/g(pCi/g)Bq/g(pCi/g)

Villagemean 0.063(1.7) 0.046(1.2)

Islandmean 0.13(3.5) 0.097(2.6)

Averageindividualinhalationintake Bq/y

(pCi/y)Bq/y(pCi/y)

0.044(1.2) 0.023(0.62)

Averageindividualcommittedeffectivedose mSv/y

(mrem/y)mSv/y(mrem/y)

0.0027(0.27)

0.0016(0.16)

aAdaptedfromRobisonetal.(1993),projectedto1995.

Ingestion

LocalsourcesofingestedradionuclidesconsideredintheLLNLassessmentincludesoil(incidentalingestion),drinkingwater(fromrainfallandgroundwater),anddiet(marineandterrestrialfoods).Theradionuclidesofpotentialimportance,becauseoftheirpresenceintheenvironmentarecesium-137,strontium-90,plutonium-239,plutonium-240,andamericium-241.Therelativecontributionstoprojectedradionuclideintakefromlocalsourcesaresummarizedin

Table5-2fortwoLLNLscenarios:A,imported-foods-available,andB,imported-foods-unavailable.

Theassessmentassumedanaveragesoilingestionof100mg/d.Forthemodelsused,soilmakesasmallcontributiontotheintakeofcesium-137andstrontium-90butitisthemajorcontributoroftransuranicsinScenarioAandanimportantcontributorinScenarioB.Thus,adosefromingestionoftransuranicsissensitivetotheassumptionsaboutthequantityofsoilintake.Theassessmentusedtheaverageisland-soilradioactivityvalues,andthedosesare

Table5-2.LocalSourceContributionstoIntakebyIngestionofVariousRadionuclides

Contributions

Component massintake,g/d 137Cs 90Sr 239,240Pu 241Am

ScenarioA-importedfoodsavailable:

Soil 0.1 0.2% 3.6% 72.3% 81.1%

Watera 977 0.05% 3.6% 1.0% 0.5%

Localfood 375 >99% 92.8% 26.7% 18.4%

Intake,Bq/d 31 0.47 0.018 0.012

ScenarioB-importedfoodsunavailable:

Soil 0.1 0.07% 1.1% 35.0% 54.0%

Waterb 530 0.01% 1.0% 0.4% 0.3%

Localfood 1,011 99.9% 97.9% 64.6% 45.7%

Intake,Bq/d 78 1.5 0.037 0.018

aIncludingrainwater,wellwater,anddrinkingwaterincoffeeorteaandmalolo.

bIncludingrainwaterandwellwater.

higherthanwouldbeestimatedwiththelowervillage-vicinityvalues.

TheLLNLassessmentassumesthatthedrinking-watersourceisrainwater60%ofthetimeandgroundwater40%ofthetime.ThedietmodelforScenarioAuses947gforthetotaldailyintakeofrainwater,wellwater,andwaterusedtobrewcoffeeorteaandB.Thus,thedosefromingestionoftransuranicsissensitivetotheassumptionsaboutthereconstitutedrieddrinks(malolo).ThequantityofwaterspecifiedforScenarioBisonly530gwiththeabsenceofcoffeeorteaand

malolo.ThesequantitiesarelessthanthedailywaterreguirementsgivenfortheICRP-23referencepersons(ICRP,1975),fluidwatervaluesof1,700g/dayforthemale

and1,200forthefemale.Thequantityofwaterspecifiedinthesescenariosthereforeseemslow.Forthewater-consumptionquantitiesused,theradionuclideintakesareprobablyoverestimatedgroundwater(withhigherradionuclideconcentrationsthanrainwater)isusedonlyinconditionsofextremedrought,buttheassessmentassumedrelativelyhighgroundwateruseof40%.However,neitherthedailyquantitynorthepercentageofgroundwateriscritical,inthatitappearsthatdrinkingwaterwouldcontributeonlyafewpercent,atmost,oftheprojectedradionuclideintake.

Theremainderofthedietconstitutesthemajorsourceoftheprojectedfission-productintakeandcontributesalargefractionoftheprojectedtransuranicintake.Averageradionuclideconcentrationsforthevariousfooditemsvaryoverarangeof105;consequently,thecompositionofthedietmodeliscriticaltothedoseassessment.Dietmodelswerereviewedinprevioussectionsofthisreport;thissectionaddressesprimarilythedose-estimationmethodanddosesestimatedwiththeLLNLdietmodel.

IntheLLNLassessment,thescenario-basedradionuclideintakeswereconvertedtodoseswiththemethodsandmodelsofICRP-30,-48,-56,and-61(ICRP,1979,1986,1989,1991b).Onespecialconsiderationwastheuseofgastrointestinal-to-bloodtransferfactors(f1values)of10-4forplutoniumingestedinsoilandtheICRPvalueof10-3forplutoniuminothermedia.Intakesoftheseradionuclideswerepresentedasfractionsoftheintakelimitcorrespondingto1mSv/y(ineffect,thecommittedeffectivedoseinmillisieverts/year).IngestionintakesandtheassociatedcommittedeffectivedosesprojectedfortheinitialyeararesummarizedbyradionuclideforthetwoscenariosinTable5-3.

TheLLNLassessmentdidnotmakeage-specificdoseestimates.However,dosesfromingestionofthemajorcontributor,cesium-137,

arefairlyconstantwithagefrom1ythroughadultlife(see,forexample,ICRP-56,1989).Also,RobisonandPhillips(1989)calculateddosesfromcontinuousintake,beginningatvariousages,ofcesium-137andstrontium-90fromanintakesourcedecayingwitha30-yhalf-life.Thesecalculationsindicatedthat,althoughmaximumdoseratesoccurredwhenintakebeganatanearlierage,4estimatedintegraleffectivedosesforadultsduetointakeofcesium-137andstrontium-90canbeusedasconservativeestimatesforintakebeginningatearlierages.

Insummary,estimatesofradionuclideingestionwerebasedonasubstantialdatabase.Allthecredibleroutesofingestionappeartohavebeenconsidered.Theestimateofthesoil-ingestionroutewouldbeimprovedbystrongerdataonquantitiesofsoilingested,particularlyasafunctionofage.Theestimationofingestionduetowaterisnotclear,particularlyinScenarioB;however,drinkingwaterdoesnotappeartobeamajordosecontributor.Thedietmodelplaysanimportantroleandhasbeendiscussedinanearliersection.TheconversionofintaketodoseusesacceptedICRPmodelsandmethods.Theassessmentwaslimitedtoareferenceadult;however,evidencewasgiventosupportthepositionthatthisprovidesaconservativeassessmentforthebroaderpopulation.Apossibleexception,notthoroughly

4Themaximumdoserateforcesium-137wascalculatedtooccurwhenintakebeginsatage4monthsandtohaveavalueabouttwicethatforintakebeginningasanadult.Forstrontium-90themaximumrateoccurredwhenintakebeganaboutage13;thisvaluewasslightlygreaterthanforintakebeginningasanadult.

Table5-3.SummaryofAnnualWhole-BodyDosesAttributabletoLocalFalloutProjectedfor1995

Route ScenarioA.ImportedFoodAvailable

ScenarioB.ImportedFoodUnavailable

Radionuclide IntakeBq/y

Dose*mSv/y

%ofTotalDose Intake

Bq/y

Dose*mSv/y

%ofTotalDose

Ingestion

137Cs 11,000. 0.16 56 28,000 0.40 73

90Sr 170. 0.0057 2 550 0.018 3

239,240pu 6.6 0.0033 1 14 0.008 2

241Am 4.4 0.0029 1 6.6 0.0044 1

Subtotal 0.17 60 0.43 79

Inhalation

239,240Pu 0.044 0.0027 1

Table5-4.CalculatedAverageAnnualWhole-BodyDosetoRongelapResidentsAssociatedwithPotentialDietaryScenariosConsideringVariationsinEnergyIntake,FoodChoices,andRemediationwithKCl(Projectedfor1995)

Ujelanglocal&importeddiet

Ujelanglocalonly

Localonly1

Coconutcollector'sdiet2

Localonlyfromnorthernislets3

LocalonlyKClapplied4

(A) (B) (C) (D) (E) (F)

137Csintake,

kBq\y 11 28 66 56 106-396 12

137CsDose,

mSv/y 0.16 0.40 0.92 0.78 1.50-5.57 0.17

Othersources,5

mSv/y 0.13 0.14 0.14 0.14 0.14 0.14

Totallocalsourcedose:

mSv/y 0.29 0.54 1.06 0.92 1.64-5.71 0.31

mrem/y 29 54 106 92 164-571 31

*Robisonetal.,1992;1993,Tables5and6.

1Ujelanglocal-food-onlydietadjustedbythecommitteetoprovideenergyequaltotheUjelanglocal-and-imported-fooddiet(ColumnB×2.305)tobringcaloricintaketoasustainablelevel.

2EnergyintakeofUjelanglocaldietincreasedbyincreasingintakeoffish(two-fold),coconutjuice(five-fold),drinkingcoconutmeat(five-fold),sproutedcoconut(five-fold),consumptionofturtleeggsreduced(90g)andof

waterreduced(300g)tomakedietquantitieslogical.

3LocaldietinColumnCbutwithpandanus,coconut,andarrowrootcollectedinnorthernisletsofRongelapandRongerikAtolls.Kohn(1989)estimatedwholebodydoses2-to9-foldgreaterthanonRongelapIsland.

4LocaldietinColumnCwithanassumed90%lossofcesium-137incoconutbreadfruitandpandanusbecauseofKClfertilization(Robisonetal.,1993).

5Allinternalandexternalsourcesofradiationotherthanthoseduetocesium-137.

componentsofthedietotherthanthosefromcesium-137havebeenheldconstant.Forafirstapproximation,thedoseassociatedwithcesium-137(projectedfor1995)hasbeencalculatedonthebasisoftheestimateddailycesium-137intakeforthevariousdietaryscenarios.

ComparisonoftheresultsofthedietaryscenarioslistedinTable5-4showstheimpactofdietaryassumptions.AlthoughtheaverageannualdosecalculatedincolumnsAandB

islessthan1mSv(100mrem),theaverageannualdosescalculatedincolumnsCandDarearound1mSv,indicatingthatasizablefractionofthepopulationwillexceedthe100-mremlimitoftheMOUifthesedietscenariosarevalid.InthescenariopresentedincolumnE,theaverageannualdoseexceeds1mSv(100mrem).

TheeffectofmitigationcanbeseenincolumnF;allassumptionsareidenticalwiththoseofcolumnC,butKClisappliedtoreducecesium-137uptakeinfoodplants.Inthiscase,thecalculatedannualdoseissimilartothatcalculatedifthelocal-fooddietissupplementedwithimportedfoods.Obviously,thereisbenefittomitigationwithKCl,andvariousexposurescenarioscanbeusedtoinvestigatepotentialeffectsofotheractionsthatmightbetaken.

Intakethroughskin

TheeffectofskincontaminationwithplutoniumhasnotbeenaddressedinthepublishedLLNLreports.ApplicationofthepreviouslycitedabsorptionfactorsfromtheliteraturewouldprojectsubstantialintakeofplutoniumfromRongelapsoil.SuchprojectionsappliedtoRongelap,however,wouldbeexpectedtoproduceanoverestimate,becausetheplutoniuminthatsoilisofafired-oxideformthatissubstantiallylesssolublethanthenitrateformsusedinmostoftheexperimentsintheliterature.ThisissupportedbythehistoryoflowexcretionofplutoniummeasuredinpersonswhoresidedonRongelap1957to1985.However,becauseoftheuncertaintiesintheprojections,assessmentsshouldbeperformedonthepotentialintakeofplutoniumthroughtheskin.

6.UncertaintyandVariabilityinDoseProjectionTwoapproachescanbeusedtodefinemaximallyexposedpersonsinriskassessments:theprobabilisticapproachandthescenarioapproach.TheprobabilisticapproachspecifiesfrequencydistributionsforquantitiesthatarerelevanttodoseorriskandthenusesMonteCarlosimulationtoestimatethepopulationdistributionofdoseorrisk.Thisapproachusesstatisticaldistributionstodefineamaximallyexposedperson.IntheRongelapassessment,thedistributionofdosestoindividualsisestimatedfromdistributionsofdiet,biologicalhalf-life,andradionuclideconcentrations.Theaveragedosetothemaximallyexposedpersonisestimatedassomehighpercentile(e.g.,the99thpercentile)oftheindividualdosedistribution.Itisnotpossibletoworkbackfromthedosereceivedbythemaximallyexposedpersonanddeterminethecharacteristicsofthatperson.Theuncertaintyinthedoseisaconsequenceofthevariabilityinradionuclideconcentrationsintheenvironmentanduncertaintiesinthedosimetrymodelsandcoefficients.

LLNLProbabilisticApproach

TheLLNLmodelextendsthestandardprobabilisticapproachbydividingtheuncertaintyinthedoseintothevariabilityamongpersonsandtheuncertaintyinthedosetoaspecificindividual(Robisonetal,1993;BogenandSpear,1987).Thevariabilityamongpersonsdependsonindividualdiet(intakeofradionuclides),thebiologicalhalf-lifeofcesium-137,andthefractionofingestedcesiumstoredinthelong-livedbodycompartmentofdifferentpersons.Theuncertaintyinaperson'sestimateddosedependsonvariabilityinradionuclideconcentrationsintheenvironmentanduncertaintyinthedosemodel

usedanditscoefficients(Fig.10).

TwosourcesofdatacontributetotheLLNLdoseassessment:characteristicsofpeopleandcharacteristicsoftheenvironment.Thesamplesizeusedtoestimateenvironmentalcharacteristicsismuchlargerthanthesamplesizeavailabletoestimatethecharacteristicsofthepeople(seeTable2-3).Accordingtothecurrentassessmentofsourcesofvariationinthedoseassessment,theinterindividualcomponentsofvariationaremuchlargerthantherandomenvironmentalvariation(Robisonetal,1993).Thelargeamong-individualvarianceandsmallsamplesizesforindividualcharacteristicslimittheusefulnessoftheindividualvariability.Estimatingtheentiredistributionofindividualdosesismathematicallysophisticated,butitdependsonparticularassumptions:

ThenativedietofthepeoplereturningtoRongelaphasexactlythesamemeanandvarianceaswereobservedinthesampleof34peopleonUjelang,andthebiologicalturnovertimeofcesium-137hasexactlythesamemeanandvarianceaswereobservedinthesampleof23Marshallese.Thisassumptioninvolvestwosub-assumptions:

Figure10.Contributionstotheuncertaintiesinindividualdosesfromvariationsamongindividualsandfrom

uncertaintiesindoseparameters.

Therearenosystematicdifferencesbetweenthepeopleinthedietorbiological-turnoverstudiesandtheRongelappeople.

Themeansandvariancesobservedinthesamplesareexactlythesameasthetruemeanandvarianceinthepopulation.Samplemeansandvariancesusuallydifferfromthetruepopulationvaluesbecauseofrandomsamplingfromavariablepopulation.Smallsamples,suchasforthedietandbiological-turnoverdata,areusuallyhighlyvariable.TheMonteCarlosimulationignoresthesamplingvariationandusesthesampleestimatesofmeanandvarianceastheparametersofthetruedistribution.

Thevarianceindailycesium-137intakeamongpersonsishighlyinfluencedbytheextremevaluesinthedistributionofdailycesium-137intake.IntheUjelangdietsurvey,thedietsthathavethehighestdailycesium-137intakewerethosewhosedailyintakewaspoorlyestimated.Theprecisionoftheestimateoftotalcesium-137intake,foragivendiet,dependsontheprecisionofthemeasurementsofcesium-137concentrationineachfoodstuff.Thestandarderrorofthetotalcesium-137intake,givensomefixeddiet,canbeexpressedas

whereW,istheintakeofitemi,siisthestandarderrorofcesium-137concentrationinitemi,andStotalisthestandarderrorofthetotalcesium-137intake.Foodstuffsthatarelargecomponentsinthediet(i.e.havelargeW1)havethelargestinfluenceontheprecisionofthetotalcesium-137intake.Ifthecesium-137concentrationinthosefoodstuffsispoorlyestimated,thenthetotalcesium-137intakefromthatdietwillbepoorlyestimated.

Largevaluesofcesium-137intakearepoorlyestimated,buttheaveragecesium-137intakeisrelativelypreciselyestimated,seeforexample,Table6-1.Femalenumber17intheUjelangdietsurveyhas

thehighestdietaryintakeofcesium-137,buttheapproximatedstandarderrorforherintakeisextremelyhigh,75Bq/day,becausesheconsumesalotofchickenandpapaya.Meanspecificactivitiesforbothpapayaandchickenpartsarepoorlyestimatedbecausethesamplesizesaresmall.Thenextlargestcesium-137intakeisrelativelywellestimated(standarderror=4.2Bq/day,Table6-1)becausethelocalfoodcomponentsofherdietareprimarilycoconutsandbreadfruit.Thestandarderrorofthethirdlargestintakeisrelativelylargebecausethatdietincludesalotofpapayaandpork.Incontrast,thecesium-137intakefromtheaverageimported-foodsavailabledietisrelativelywellestimated(Table6-1).

Dietaryintakeandbiologicalhalf-lifeofcesiumareindependent.Thatwouldnotbetrueifpeoplewithhighdietaryintaketendedtohavehighercesiumbiologicalhalf-lives.Bodyweightiscorrelatedwithhighdietaryintakeandmightbecorrelatedwithbiologicalhalf-lifeinadults(Miltenbergeretal.,1981;Leggett1986).Ifbodyweightispositivelycorrelatedwithbothdietaryintakeandcesiumbiologicalhalf-life,thenintakeandhalf-lifewillbepositivelycorrelated,violatingtheassumptionofindependence.

Table6-1.Estimateddailyintakesandapproximatestandarderrorsfortheimported-foods-availabledietandthethreewomenintheUjelangdietstudywiththelargestestimatedcesium-137intake

Diet EstimatedCsintake

Approximatestandarderror*

Imported-foods

31Bq/d 2.9Bq/d

OfFemale#17

173Bq/d

74.Bq/d

OfFemale#15

103Bq/d

4.2Bq/d

OfFemale#16

60Bq/d 12.Bq/d

*Thesestandarderrorsareapproximate.TheyarecalculatedfromtheUjelangdietsurveyrawdataanddatainRobisonetal,1993,tables20andB-1.Thecalculationsareunderestimatesofthetruestandarderrorbecausetheyassumerandomsamplingoffoodstuffs,independentestimatesofcesium-137concentrationsinallfoodstuffs,andnosamplingerrorincertainfoodstuffs(e.g.mostseafood).

Lognormaldistributionsareappropriatetodescribethedistributionofbodyweights,dietaryintakes,andbiologicalhalf-livesforcesiumintheRongelappopulation.SpecialconcernshouldbegiventowhethertheuppertailofthelognormaldistributionappropriatelymatchesextremevaluesintheRongelappopulation.TheLLNLdoseassessmentdoestestwhetherthedatafitlognormaldistributions(Robisonetal.,1993).Noneofthetestsrejectsthehypothesisthatthedistributionsarelognormal,butfailingtorejectdoesnotprovethat

thedistributionsarelognormal,especiallyinthetails.Thetestsofnormalityorlognormalityhavelowpower,especiallywhenthesamplesizesaresmall(Shapiroetal.,1968).Inotherwords,datamightappeartobelognormalevenifthetruedistributionisnotlognormal.InspectionoftheprobabilityplotsgiveninRobisonetal.,(1993)suggeststhatlognormaldistributionsmightnotbeappropriatetorepresenttheextremetailsofthetruedistributions.Ingeneral,thelargestandsmallestdatapointsdeviatethemostfromthepredictedquantilesforlognormaldistributions(e.g.,seeFigs.6,8,10,and11ofRobisonetal.,1993).Tosomeextent,thatisexpectedbecausethevarianceofextremevaluesislargerthanthevarianceofthemedian.Itisnotclearwhethertheextremevaluesaremoredeviantthanwouldbeexpected.

TheissueoftheappropriatedistributiontouseintheMonteCarlosimulationisimportantbecausesomesortofdistributionalassumptionmustbemadetoextrapolatetoextremepercentiles.Thesamplesizesforthedietandbiologicalhalf-lifesamplesaretoosmalltousenonparametricestimatesoftheextremepercentiles.The99percentilecannotbeestimatedunlesstherearemorethan50observations,anditisnotreliablyestimatedunlessthesampleisconsiderablylarger.

Thereisnomeasurementerrorincludedinanyofthevarianceestimates.TheMonte-Carlouncertaintyanalysisusesthebetween-individualvariancesindietaryintake,biologicalturnover,andotherquantitiestocalculatethedistributionofannualdosestoindividuals.TheMonte-Carloanalysisassumesthattheobservedbetween-individualvariancesestimatethetrue

varianceamongindividuals.Undersomesimplifyingassumptions,theobservedvarianceamongindividuals( )isthesumofthetrueinter-individualvariance( )andthemeasurementvariance( )(Searleetal.,1992).Thatis,

Hence,theobservedvarianceestimatesthetruebetween-individualonlywhenthereisnomeasurementerror.However,thereissomemeasurementerrorassociatedwithalldata.Table6-1showssomeoftheestimatedmeasurementerrorsfordietaryintake.Thereisalsoameasurementvarianceassociatedwithestimatesofbiologicalhalf-life,butwehavenotestimatedit.Ifestimatesofmeasurementerrorareavailable,e.g.fromrepeatedsamplingofindividuals,then canbeestimatedseparatelyfrom .TheeffectsofmeasurementerrorindietarysurveysonthedistributionofusualdietaryintakeandsomeapproachestocorrectforitareexploredbyNusseretal.(1990).

Thoseassumptionshavedifferenteffectsonthedistributionofdosestoindividuals.Accountingforsamplingvariation(thefirstsub-assumption)increasesthevarianceinthedosedistributionandsoincreasestheprobabilityofalargedosetoanindividual.Theeffectofcorrelateddietaryintakeandbiologicalhalf-livesdependsonthesignofthecorrelation.Iftheyarepositivelycorrelated,theprobabilityofextremedosesishigher;iftheyarenegativelycorrelated,theprobabilityislower.Theeffectofmis-specifyingthetailsofsomedistributiondependsonwhetherthetailsofthetruedistributionaremoreorlessextremethanthoseofalognormaldistribution.Iftheyaremoreextreme,theprobabilityofanextremedosewillbehigher.Accountingformeasurementerrordecreasestheamong-individualvariance,whichdecreasestheprobabilityofanextremedosetoanindividual.

Theneteffectoftheassumptionsandsmallsamplesizesdefiningthe

characteristicsofindividualsisthatthetruedistributionofdosestotheRongelappopulationuponresettlementmightdifferfromthecalculateddistribution(Robisonetal.,1993,Fig.18).Thedifficultystemsfromuncertaintiesincharacterizingthevariabilityamongindividuals.Usingscenariosforestimatingexposureandestimatingthedistributionofdosesforspecificscenariosavoidstheproblemofestimatingthevariabilityamongindividuals.

ScenarioApproach

Inthescenarioapproach,onecaneasilydefinecharacteristicsofamaximallyexposedperson.FortheRongelapassessment,scenarioscanbeusedthatspecifythesex,weight,anddietforanyindividualsituation.Thescenariocouldalsoincludethelifestyle,biologicalhalf-lifeofcesium,andfractionofcesiumgoingtothelong-livedbodycompartment.Ascenarioforthe''criticalgroup''thatdefinesthemaximallyexposedpersonmightspecifythesex,weight,anddietofthatgroup.Alternativescenariosshouldexploretheimpactoffoodconsumption(kilograms/day),effectsofbinges(e.g.,consumingalargenumberofcoconutcrabsinashortperiod),effectsofdifferentlifestyles(e.g.,primarilyharvestingandeatingcoconutsorprimarilyfishing),andtheimpactofKClappliedtothesoilasafertilizer.Theaveragedoseanditsuncertaintyarecomputedforthatcombinationofcharacteristics.

Theuncertaintyintheaveragedosesfromthevariousscenariosmightincludeoneorall

oftherelevantsourcesofvariabilityintheinputdata:dailyvariationindiet,variationinradionuclideconcentrationinthefoodstuffs,orbiologicalhalf-lives,anduncertaintiesinthedosimetrymodelsandcoefficients.Individualvariabilityinbiologicalhalf-livescanbedealtwithinoneofthreeways:addingaspecificationofbiologicalhalf-lifetothedescriptionofthescenario,fixingthecesiumbiologicalhalf-lifeat110d(theICRPaverageadultvalue),orincorporatingvariabilityinthebiologicalhalf-lifeintheuncertaintyinthedose.Ifthelatterapproachistakenthedatabaseonbiologicalhalf-livesintheRongelap(orMarshallese)populationmustbeexpanded.

Thescenarioapproachtoriskassessmentisoftenused.Becausetheriskiscomputedforapersonwithspecificcharacteristics,itispossibletoidentifythecharacteristicsassociatedwithhighdoseanddecidewhetheranypersonislikelytopossessthosecharacteristics.

Conclusions

ThereliabilityoftheprobabilisticapproachforestimatinguncertaintyinthedosetoreturningRongelappeopleislimitedbythesparsenessofinformationonvariabilityamongindividuals.

Ascenarioapproachmightbemoreeffectivebecauseitcanidentifyeventsthatcontributetohighdoses.AsuiteofrelevantscenariosshouldbedevelopedincollaborationwiththeMarshallese.

7.DoseLimitsandTheirApplicationsThiscommitteewaschargedtoreviewandcommentontheapplicabilityoftheICRPrecommendationsonannualdoselimitsforgeneralpopulationsastheypertaintoanticipateddosecommitmentsafterresettlementincontaminatedareasoftheMarshallIslands.

Thequestionofapplicabilityissomewhatacademic,inasmuchasradiologicalcriteriaforthedecisiononresettlementhavebeenagreedonandarepresentedintheMOU(ArticleV,paragraph1).ThesecriteriaarethatnopersonresettlingonthesouthernislandsofRongelapAtollandsubsistingonalocal-food-onlydietwouldreceiveacalculatedannualeffectiveradiationdoseexceeding100mremabovenaturalbackgroundorwouldbeincidentallyexposedtoconcentrationsoftransuranicsinthesoilinexcessoftheprescribedactionlevelof17pCi/g.ItshouldbenotedthatthecommitteehadseriousreservationsregardingtheMOUprovisionrelatingtoadoselimit,oractionlevel,basedonthemaximallyexposedindividual.Radiationstandardsandthetechniquesusedinradiationdosimetrydonotlendthemselvestothedeterminationofdosetothemaximallyexposedindividual.Thisisparticularlytrueforapopulationoflimitedsizewherethestatisticalpowerfordeterminingdosesattheextremesofthedosedistributionsislimited.ThecommitteewasinformedbyDOErepresentatives,however,thatthislimitwastobeusedonlyasaguidelineforresettlementdecisionsandthat,asaninternationallynegotiatedparameter,weweretoconsideritasafixedparameter.

Theactionlevelof17pCi/gforplutoniumsoilconcentrationsisbasedonaU.S.EnvironmentalProtectionAgencyactionlevelof0.2mCi/m2forpublicprotectionfromaccidentalcontaminationofthe

environment.TheEPAactionlevelwasdevelopedforapplicationtorecentcontamination,thusalloftheradioactivecontaminationwasconsideredtobeconcentratedwithinthetop1cmofthesoil.Withthisapproach,soilconcentrationslessthentheactionlevelwouldwarrantnofurtheraction.TheMOUactionlimitof17pCi/gwasderivedbyDOEfromthis0.2mCi/m2EPAguidelineusingasoildensityof1.2g/cm3appropriatetoRongelapandassumingthattheradioactivitywasinthetop1cmofsoil.BecausethecontaminationonRongelaptookplacenearly40yearsagotheinitialconcentrationofradionuclideshasleachedintothesoilcolumnandnolongerresidesonthesurface.Inadditionthevegetationcyclehasproducedapproximately1cmoffreshorganicmaterialoverthelastthreedecades.Takingtheseconsiderationsintoaccount,theMOUconsidersthepotentialforsubsequentradionuclidemigrationinthesoilbyprovidingprovisionsforaveragingofthe17pCi/gradionuclideconcentrationoverthetop5cmofsoil.

TheannualdoselimitrecommendedformembersofthepublicbyICRPisnotintendedtobedirectlyapplicabletodecisionsonwhentoreturntoanareathathasbeenevacuatedbecauseofradiologicalconcernsraisedbypotentialoractualradiationcontamination.Inthelattercircumstances,ICRPrecommendsthatthedecisiontoreturntoapreviouslyevacuatedareaisjustifiedwhenbeingbackismorebeneficialtothepeopleinvolvedthanremainingaway.Theassessmentofwhichismorebeneficialmusttakeintoaccountallthefactorsthat

influencehealthandwell-being.Apopulationmightexpecttoachievethegreatestnetbenefitbyappropriateallocationofwhateverresourcesithasavailabletoitwithinthecontextofallthefactorsthataffectitshealthandwell-being.Itfollowsthatinanyspecificsituationbroughtaboutbyintervention,adecisionbyadisplacedpopulationneedstobemadeonthebasisoffactorsthathavethegreatestinfluenceonthem.Thereisnoreasontoexpectthatthemagnitudeofanyparticularfactor(forexample,residualcontamination)onwhichadecisiontoreturnisbasedwillbethesamefromcasetocase.Eachpopulation'ssituationwillinvolvedifferenttradeoffs.

ICRPrecognizesthatnumericalcriteriaactionlevelsareoftenhelpfulinmakingdecisions;inthisinstance,suchcriteriahavebeendefinedintheMOU.ImplicitinthewordingoftheMOUisthatthepartiestoitbelievedthatanetbenefitwouldaccruetothedisplacedpopulationwhentherecouldbeassurancethat,ontheirreturntoRongelap,themaximumannualdosereceivedbyanypersonandtheconcentrationoftransuranicseverywhereinsoilhadnaturallydecreasedorhadbeenreducedtostatedactionlevels.Withthoseconditionsmet,resettlementwouldbejustified.

TheMOUisnotclearonhowthespecifiednumericaldoseandconcentrationcriteriaaretobeapplied,i.e.,howdoesonedefinethemaximallyexposedperson?Fortheindividualdose,thegeneralapproachininterventionistoapplythecriteriatothegroupinvolvedasawhole,ifitissmallandisreasonablyhomogeneous,ortoadefinablesubsetofthegroupwhosecircumstancesandhabitsarereasonablysimilarandtypicalofindividualswhocouldberegardedasthosemaximallyexposed.Thelatteristheconceptofthe"criticalgroup."Variouscombinationsofhabitsandenvironmentalfactorsareusuallyexaminedindecidingthecharacteristicsoftheindividualsinthecriticalgroup.ForthereturningRongelapcommunity,suchasubsetcouldbeagroupthathasaparticulardiet,somedefined

fractionofwhichislocallygrownfood.Forapplyingthecriteriononsoilconcentration,anothersubsetofthepopulationcouldbeagroupofchildrenwhosetimeisspentplayinginparticularareasandwhosedailysoilingestioncouldbedefined.Suchdefinitionofthegroupofmaximallyexposedchildrenprovidesthebasisforinterpretingthenumericalcriterionfortheconcentrationoftransuranicsinsoil.Theareaanddepthofsoiloverwhichtheconcentrationoftransuranicsshouldbeaveragedcanbedeterminedbyconsideringthehabitsand,ineffect,samplingsuchagroupofchildren.

Thoseareexamplesofthescenarioapproachdiscussedinthesectionondietmodels.Thealternativeistotakethestatisticalorprobabilisticapproachandassesstheprobabilitythatagivenfractionofthepopulationmightreceiveamaximumannualdoseaboveagivenvalue.Theprobabilitythatagivenconcentrationinsoil,whenaveragedoveragivenarea,willbeexceededcanalsobeestimated.

8.RecommendationsforRemedialActionThecommitteehasconcludedfromitsstudyofavailableinformation(Chapters2-6)thattheannual-dosecriterionmightnotbemetforeveryindividual.However,theannual-dosecriterionmaybeconsideredasanarbitraryactionlevelthatdoesnotpresentanabsolutebarriertoresettlement.Remedialactionsshouldnotbejudgedsolelyonthebasisofaneedtomeetanactionlevel,butasameanstoincreasethephysicalandpsychologicalwell-beingoftheRongelappeopleiftheydecidetoresettle.

Knowledgeofthechemistryofcesiumandplutoniumandanunderstandingoftropicalecosystemscanbeusedtodeviseasetofpotentialremedialactions.Thefollowingconstitutemeansofremedialactionsnotmeanttobeall-inclusivethatcouldsubstantiallyreducetheamountofradiationreceivedbypeoplelivingonRongelap.

1.Thefirstgenerallyacceptedremedialaction,impliedintheMOU,andrecommendedbythiscommitteeisthatthelocal-food-onlydietislimitedtofoodgatheredonthesouthernislandsofRongelapAtoll.ThepotentialconsequencesofnotfollowingthisrecommendationandofconsumingfoodcollectedonthenorthernisletsofRongelaporRongerikAtollaresummarizedincolumnEofTable5-4.Exposuretocesium-137couldbeincreasedbyafactorof8-32ifallpandanus,coconut,andbreadfruitwerecollectedonthenorthernislets.Amajorconsequenceofrestrictedaccesstothenorthernpartsoftheseatollswillbetolimitavailablefoodresources.

2.PeoplelivingonRongelapwillreceivemostoftheirexposuretocesium-137fromsurfacesoil,eitherthroughdirectirradiationofthebody(externaldose)orthroughingestionofplantsthathaveextracted

cesium-137fromthesoilduringgrowth(internaldose).Itisrecommendedthatthereturningpopulationrestrictthequantitiesofsomelocalfoodsintheirdiet.TheeffectivenessofthisactisobviousinthedoseprojectionsofTable5-4.Exposuretocesium-137maybereducedbyafactorofgreaterthan5whenimportedfoodsaresubstitutedforsomelocalfoods(i.e.,dietAversusdietCinTable5-4).AmodestsupplementaryfoodprogramwouldhelpthereturningRongelappeopletoobtainthenecessaryquantitiesofimportedfood.

3.Actionsthatreducethedirectexposurefromsubsurfacecesium-137orreducetheuptakeofcesium-137fromthesoilbylocalfoodstuffsarealsolikelytoreducethemaximumannualdose.Onesuchactionistoremovetheupperlayerofsurfacesoilfromthevillageandoneachhouseplot(Robisonetal.,1993).Anotheristoaddalayerofcrushedcoralaroundthehousesandtocommonareasofcongregationthroughoutthevillage.BoththeseactionsarerecommendedastheycouldbeaccomplishedashousingisrebuiltonRongelapIslandbeforeresettlementwithlittleimpactonresettlementactivities.

4.ThecommitteealsorecommendstheapplicationofKClasfertilizerandforremediationinagriculturalareas.TheapplicationofKClwouldreducetheuptakeofcesium-137bycoconut,breadfruit,andpandanusfruit.RobisonandStone(1992)havedemonstratedtheeffectivenessofKClinreducingcesium-137incoconutsgrownonBikiniandinincreasingplantgrowthintherelativelypotassium-deficienttropicalsoilsofthenorthernMarshallIslands.PotassiumchlorideisacommonfertilizerusedintheUnitedStateswithnoknowndetrimentalhealtheffectswhenusedintheconcentrationscommonlyappliedasacommercialfertilizer.Thisformofremediationrequiresonlymodesteffortandhasnoreporteddetrimentaleffectsforhumansorotherpartsoftheecosystem.

5.Theremovalofthetop30-40cmofsoilfromtheislandisanotherpotentialremedialaction.However,thisapproachisnotrecommended;ithashadsubstantialeffectsonlifestyleandontheenvironmentofEnewetokAtoll.Giventhefragileecologyofthesecoralislandstheregenerationoftopsoilremovedinsuchanextremeproceduremayrequiredecades,orevencenturies.Suchanextrememeasureshouldbeoneoflastresort;onthebasisoftheprojecteddosesachievablewithmoremoderatemeansofremediation,itappearsunnecessary.

Continuationofremedialactions1,2,and4mightberelaxedifmonitoringindicatesthatwhole-bodyburdensarelowerthanestimated.

9.RecommendationsforPost-ResettlementMonitoring

RadiationDosimetry

Toensurethecontinuedwell-beingofthepeopleofRongelapandtoensurethattheconditionsoftheMOUarebeingmet,continuingpost-resettlementradiationsurveillancewillbenecessary.Forthepurposesofthisdiscussion,weestimatethatabout400personswillelecttoreturntoRongelap.Wesuggestthatthispopulationinitiallybeunderrathertightsurveillance,whichcanberelaxedasexperiencedictates.

Itissuggestedthatthefollowingactivitiesbeinitiatedbeforeandcontinuedafterresettlement:

1.Eachpersonshouldreceiveawhole-bodycount(WBC)beforeresettlementandawhole-bodycountannuallythereafterwiththecountingactivitytobeconductedduringoneoffoursuchactivitieseachyear.

2.Acohortof80personsstratifiedbyageandsexdrawnfromtheestimated400whomaychoosetoresettlewillbemonitoredforwhole-bodyradionuclideburdensateachofthefourWBCcountingperiods.Thiswillprovidecohortdataonpotentialseasonalvariationsintheradionuclideintake.Personsfoundatanannualcounttohaveunusuallyhighbodyburdensshouldbeimmediatelyrecountedtodeterminewhethererrorsincountinghadoccurred;ifnot,theyshouldbeaddedtothegroupsampledquarterlyuntilthecause(s)oftheirhighbodyburdensisidentified.Dietaryintakeshouldbeassessedeachtimewhole-bodycountingisconducted;thisisbestdonewithacarefullyplannedfood-frequencyquestionnaire.Thecommitteerecommendsthatthisdietarysurvey,includingthequestionnaire,be

developedinconsultationwithwellqualifiedexpertsinnutritionanddiet,andwithknowledgeofthelocalculture.

3.Abaselineurinesampleshouldbeobtainedbeforeresettlementandstoredunderidealconditionsforradioassayincaseitbecomesnecessary.Alimitednumberofsamples,chosenatrandom,shouldbeanalyzedtotestthatplutoniumlevelsremainat,orbelow,thelevelsofsensitivityofcurrentanalyticmethods(50-80aCi).Effortshouldbeexpandedtodevelopmoresensitiveanalytictechniques,includingastudyoftheemergingtechnologyofmassspectroscopy,toenablemorereliableandaccuratemonitoringoflowlevelsofplutoniuminthefuture.

4.Aneffortshouldbeinitiatedtoestablishacentralrepositoryforbothindividualdosimetryrecordsandbiologicalsamplesasreferencesforfutureindividualmedicalconcerns.

IfthemonitoringmeasurementsindicatethatthetermsoftheMOUarebeingadequatelymetandifremedialactivitiesarethenrelaxed,surveillanceshouldcontinue.Ifafterseveralyearsoffurthersurveillanceitisclear,evenwithsuchrelaxationofremedialmeasures,thatthetermsoftheMOUarebeingmet,thesurveillanceprocedurescanbefurtherrelaxed.

MedicalConsiderations

Onthebasisofcurrentradiationdoseestimates,thereisnoexpectationthatanymedicalillnessduetoexposuretoionizingradiationwilloccurinanymembersoftheresettlementpopulationoftheislandofRongelapfromeitherintakeofnativefoodsorenvironmentalcontact.Unrelatedandperceivedmedicalproblemswilloccur,however,sobasicmedical-careandmedical-surveillanceprogramsshouldbedevelopedthatarecloselyintegratedwithcontinuingbiodosimetryprograms.Thebasicprogramshouldbeconductedbytheindigenousinhabitantsoftheislandandshouldbedesignedtomeetthechallengesoftheseriousmedicalproblemsofachangingsocietyinanisolatedgeographicalenvironment.Itisanticipatedthatthemajormedicalconcernsofthefuturewillbehighincidencesofobesity,diabetes,andhypertension,mostcasesofwhicharerelatedtoincreasedacceptanceof"westernized"dietswithhighsodiumandfatcontentinassociationwitharelativelysedentarylifestyle.

ThespecificproblemsthatmustbeaddressedforthosereturningtotheislandofRongelaprequireareasonableandcontinuingmedicalprogram,whichshouldconsistofthefollowing:

1.Regularmedicalsurveillance.

2.Managementofacuteandchronicmedicalproblems.

3.Capabilitytoinvestigatechangesindietarypatternsthatmightberelatedtodiabetes,hypertension,obesity,vitamindeficiency,malnutrition,andrelateddisorders.

4.Maintenanceofindividualmedicalrecords.

5.Abilitytocollectandpreparebiologicalsamplesformedicallaboratoriesandradioassay.

6.Staffandfacilitiesforperformingbasiclaboratorytests,includingbloodcounts,urinalysis,andstoolexamination.

7.Centralmedicalcommunicationandevacuationprograms.

Toimplementthemedicalprogramnotedabove,weofferthefollowingrecommendations:

1.Facilities.Ataminimum,acentrallylocatedgovernment-operatedhealthclinicshouldbeestablished.Itshouldcontainadequatespaceandprovisionsformedicalexaminationofadultsandchildren,medicalfirstaid,abasicmedicallaboratory,anofficeforadministrativepersonnelandthemaintenanceofmedicalrecords,andequipmentfortelecommunicationwithareliablesourceofmedicalconsultation.Themedicalfacilitymightalsobeanexcellentlocationforwhole-bodycountingandthemaintenanceofindividualdosimetryrecords.

2.Personnel.Ataminimum,oneparamedicalperson(nurse,nursepractitioner,orphysicianassistant)withsometraininginnutritionandradiationeffectsshouldoperatethemedicalaspectsofthemedicalprogram.Itwouldbeadvisabletohavethatpersonbeamemberoftheresettlementpopulation.Trainingofsuchapersonshouldcommencewellinadvanceofresettlement.Heorsheshouldbecapableofconductingmedicalinterviewsandphysicalexaminations,maintainingmedicalrecords,performingbasiclaboratoryexaminations,administeringfirstaid,operatingchannelstocommunicatewithphysicianconsultants,andpreparingandstoringorshippingbiologicalsamplesforbioassay.Itisconceivablethatthesamepersonmightbetrainedtoconductandrecordtheresultsofwhole-bodycounting.

3.MedicalSurveillance.Theresettlementpopulationshouldbeencouragedtohaveregularmedicalinterviews,physicalexaminations,andlaboratorystudiesatintervalsatleastonceevery2years.Theresultsofsuchexaminationsshouldberecordedinindividualhealthrecordsandbereviewedbyaphysicianatleastonceayear.Morbidityandmortalitystatisticsfortheentireresettlement

populationalsoshouldbereviewedatleastonceayearbyaqualifiedphysicianorepidemiologist.Itisessentialthataphysicianorotherqualifiedpersonbeavailableforconsultationtodeterminewhetheraspecificmedicalproblemisradiation-related.

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Sun,L.C.,J.H.Clinton,J.McDonald,A.R.Moorthy,E.Kaplan,andC.B.Meinhold.1993.UrinecollectionprotocolintheRepublicoftheMarshallIslands.RadiationProtectionManagement10:64-72.

Taylor,R.,B.Jalatudin,S.Levy,B.Montaville,K.Gee,andT.Sladden.1991.Prevalenceofdiabetes,hypertensionandobesityatdifferentlevelsofurbanizationinVanuatu.Med.J.Aust.155:86-90.

Tobin,J.A.1952.Ujelangfieldnotes,October14-19.Typescript.AvailableattheGovernmentRecordsOffice.Majuro,RepublicoftheMarshallIslands.

Tobin,J.A.1953.Kilifoodconsumptionrecord,intheBikinipeople,

pastandpresent.Typescript.AvailableattheGovernmentRecordsOffice.Majuro,RepublicoftheMarshallIslands.

Warrick,A.W.,D.E.Meyers,andD.R.Nelson.1986.Geostatisticalmethodsappliedtosoilscience.Pp.53inMethodsofSoilAnalysis,Part1.PhysicalandMineralogicalMethods,Secondedition,A.Klute,ed.AgronomyMonograph9.Madison,WI:AmericanSocietyofAgronomy.

Wiens,H.J.1957.FieldnotesonatollsvisitedintheMarshalls1956.AtollResearchBulletin.No.54.PacificScienceBoard,NationalAcademyofSciences.Washington,D.C.;WashingtonD.C.Pp.1-23.

Wong,K.M.,G.S.Brown,andV.E.Noshkin.1978.Arapidprocedureforplutoniumseparationinlargevolumesoffreshandsalinewaterbymanganesedioxidecoprecipitation.J.ofRadioanalyticalChem.42:7-15.

Wong,K.M.,T.A.Jokela,andV.E.Noshkin.1994.RadiochemicalProceduresforAnalysisofPu,Am,Cs,andSrinWater,Soil,Sediments,andBiotaSamples.UCRL-ID-116497.LawrenceLivermoreNationalLaboratory,Livermore,CA.Pp.1-17.

Yuhas,J.A.,J.E.Bolland,andT.W.Bolland.1989.Theimpactoftraining,foodtype,gender,andcontainersizeontheestimationoffoodportionsizes.J.Am.Dietet.Assoc.87:1473-1477.

Glossarya prefixmeaning10-15whenusedasaunitdesignation,i.e.,

aCi(atto-Curie)BNL BrookhavenNationalLaboratoryBq Unitofactivityequalto1persecondBRAVOCodenamefortheU.S.nucleartestthatcontaminatedthe

RongelapAtollCi Unitofradioactivityequalto3.7X1010disintegrations

persecondDOE U.S.DepartmentofEnergyd unitoftime,dayg unitofmass,gramh unitoftime,hourICRP InternationalCommissiononRadiationProtectionLLNL LawrenceLivermoreNationalLaboratorym prefixmeaning10-6whenusedasaunitdesignation,i.e.,

mCi(micro-Curie)m prefixmeaning10-3whenusedasaunitdesignation,i.e.,

mCi(milli-Curie)MOU MemorandumofunderstandingbetweentheU.S.andthe

RepublicoftheMarshallIslands

n prefixmeaning10-9whenusedasaunitdesignation,i.e.,nCi(nano-Curie)

rem unitofabsorbeddoseNRC NationalResearchCouncilRMI RepublicoftheMarshallIslandss unitoftime,secondSv unitofabsorbeddose(1Sv=100rem)SI Internationalsystemofunitsandmeasures

WBC Wholebodycount,orwholebodycountingy unitoftime,year

AppendixMemorandumofUnderstandingbyandbetweenTheRepublicoftheMarshallIslands,theRongelapAtollLocalGovernmentCouncil,theUnitedStatesDepartmentofEnergyOfficeofEnvironment,SafetyandHealthandTheUnitedStatesDepartmentofInterior,OfficeofTerritorialandInternationalAffairsfortheRongelapResettlementProject

ThisMEMEORANDUMOFUNDERSTANDING(hereinafterreferredtoas"MOU"),ismadebyandbetweentheREPUBLICOFTHEMARSHALLISLANDS(hereinafterreferredtoas"RMI",theRONGELAPATOLLLOCALGOVERNMENTCOUNCIL(hereinafterreferredtoas"RALGOV"),theUNITEDSTATESDEPARTMENTOFENERGYrepresentedbytheOfficeforEnvironment,SafetyandHealth(hereinafterreferredtoas"DOE/ES&H),andtheUNITEDSTATESDEPARTMENTOFTHEINTERIOR(hereinafterreferredtoas''DOI/OTIA").

Witnesseth:

WHEREAS,thepurposeofthisMOUistoimplementprovisionsofTitleI,Sections103(i)and105(c)ofU.S.PublicLaw99-239;and

WHEREAS,infurtheranceoftheforegoingprovisionsofU.S.PublicLaw99-239andNitijelaResolution1986-62,RMIandRALGOVhavecausedtobepreparedthe"RongelapAtollResettlementProject

ScientificWorkPlan:,acopyofwhichisattachedhereto(andhereinafterreferredtoasthe"RongelapWorkPlan");and

WHEREAS,infurtheranceoftheforegoingprovisionofU.S.PublicLaw99-239,theU.S.CongresshasappropriatedfundsfortheimplementationandsupportoftheRongelapWorkPlanpursuanttoPublicLaw102-154;and

WHEREAS,RMIandRALGOVhaveagreedtoandshallbyafutureseparateagreementestablishaRongelapResettlementProject(hereinafterreferredtoasthe"RongelapResettlementProject")inordertofullyimplementandassuretheday-to-daymanagementofthescientificstudiesandconductotherresettlementactivities;and

WHEREAS,allthepartiestothisMOUarecommittedtotakingallactionsrequiredinordertoassurethetimelyimplementationoftheRongelapWorkPlanandsuchfutureresettlementactivitiesandactionsasmaysubsequentlyprovenecessarysuchthattheresettlementofthepeopleofRongelapmaybesecured;

NOWTHEREFORE,beitagreedasfollows:

ArticleI-General

1.TheactivitiesoftheRongelapAtollResettlementProjectScientificWorkPlan,otherwisereferredtohereinasthe"RongelapWorkPlan",areherebyendorsedbyeachofthesignatorypartiesastheproperscientificstudiesthatarenecessarytocharacterizetheradiologicalandenvironmentalconditionsofthesouthernislandsofRongelapAtoll,anduponwhichthedeterminationforresettlementofthesouthernislandswillbemadeandfurtherthat:

2.Thesignatorypartiescommitthemselves,onetotheotherandeachtoall,thatuponreceiptoffundingfortheRongelapWorkPlanpursuanttoU.S.CongressionalappropriationtheyshallfullycooperateinandsupportthecompletionoftheRongelapWorkPlanandthestudiesundertakenpursuantthereto.

ArticleIIAgreementby&BetweenDOI/OTIAandDOE/ES&H,RALGOV,andRMIfortheImplementation&ConductoftheRongelapWorkPlaninSupportoftheResettlementofthePeopleofRongelap

TheDepartmentofInterior/OfficeofTerritorialandInternationalAffairs,theDepartmentofEnergy/OfficeofEnvironment,SafetyandHealth,theRongelapAtollLocalGovernmentCouncilonbehalfofthePeopleofRongelap,andtheRepublicoftheMarshallIslandsfurtheragreethat:

[Theinitialstage-Determinationofreadinessforresettlement]

1.ThestudyandultimateresettlementofRongelapshallbeundertakeninstages,beginningwithaninitialenvironmentalandradiologicalassessmentofRongelapIslandandthoseislandscomprisingthesouthernone-halfofRongelapAtoll,saidareatoencompassonthewesternsideofRongelapAtollfromBokonlepIslandsouthandontheeasternsidefromErebotIslandsouth.

2.TheprimaryconditionofadeterminationtoinitiateresettlementfortheareadefinedinSection1ofthisArticleisthatthecalculatedmaximumwhole-bodyradiationdoseequivalenttothemaximallyexposedresidentshallnotexceed100millirem(mrem)/yearabovenaturalbackground,baseduponalocalfoodonlydiet,suchthatiftheradiologicalassessmentundertakeninaccordancewiththeRongelapWorkPlandemonstratesthatnoindividualwouldreceiveanannualradiationdoseequivalentinexcessof100mremabovenaturalbackground,resettlementwillensue.RALGOVmayatitsdiscretiongiveconsiderationtoadditionalpotentialmeasures(i.e.,applicationoffertilizers)toreduceindividualandpopulationradiationexposurestothereturningpopulationfurtherbelowthe100mrem/yearlimit.

3.The"localfoodonlydiet"declarationismeanttoconstituteatraditionalRongelapcommunitydietconsistentoflocalfoodtaken,grownand/orgatheredfromthesouthernislandsofRongelapAtollandtheimmediatelysurroundingwatersasdefinedinSection1ofthisArticle.ItisagreedthatthemakeupofaRongelap"localfoodonlydiet,"andforcomparisonpurposesamore"realisticdiet,"shallbemorepreciselydeterminedandquantifiedpursuanttotheRongelapWorkPlan,inconsultationwiththeRongelapcommunity.Initsdeterminationofwhatconstitutesa''localfoodonlydiet,"theRongelapAtollLocalGovernmentCouncilmayatitdiscretionincludeimportedfoodsthatarestaplesofthediet,e.g.rice.

4.(a)Anadditionalconditionofmitigationistheextentoftransuraniccontamination,especiallyplutoniumcontaminationofsoil.Thepartiesareagreedthatthisissue,aswellasthepossibleneedforanenvironmentalcleanupprogramsolelyfortransuraniccontamination,requirescarefuldeliberation.Tothisend,itisagreedthatthestudiesundertakenpursuanttotheRongelapAtoll,utilizingasanactionlimitthescreeningleveloftheU.S.EnvironmentalProtectionAgency("EPA")of0.2microcuriespersquaremeter,whichhasbeen

translatedbytheDOE/ES&Hintoanactivityconcentrationof17picocuries/gram(pCi/g)oftransuranicsaveragedinthetop5centimeters(cm)ofsoil.Theactionlimithasbeensetat17pCi/goftransuranicsinsoil.MeasurementoftransuraniccontaminationintheenvironmentanddeterminationofwhethertheactionlimithasbeenmetorexceededwillbemadepursuanttoanappropriateenvironmentalsamplingplandevelopedbytheRongelapResettlementProject.

(b)ShouldtheRongelapWorkPlaninvestigationsdeterminethatnosoilconcentrationoftransuranicsisinexcessoftheaforementionedprescribedactionlimit,thennofurtherconsiderationforsoilcleanupoftransuranicsiswarranted.If,ontheotherhand,itisdeterminedthatsoilconcentrationsexceedtheprescribedactionlimit,thenrecommendationastotheneedforremedialactivityand/orcleanupshallbeincludedaspartofthereportpreparedpursuanttotheRongelapWorkPlan.

(c)Totheextentthattransuraniccontaminationexistsinexcessoftheprescribedactionlimitbutislimitedinnature,controllable,anddoesnotimpactdesignateddwelling,foodgathering,foodgrowing,and/orrecreationalareas,thenresettlementmayensuewhilemitigativemeasuresareconsideredand/orundertaken.

5.IntheeventtheassessmentofRongelapAtollconductedpursuanttotheRongelapWorkPlandemonstratesthatradiologicalconditionsonBokonlepIslandorErebotIsland(andtheirimmediatewaters)exceedtheherein-definedstandardsforresettlement,theoveralldeterminationtoinitiateresettlementforthesouthernislandsofRongelapAtollshallbemadewithoutconsiderationof,andtotheexclusionof,radiologicalconditionsonBokonlepIslandorErebotIsland.

[Adeterminationofnon-readinessforresettlement]

6.IntheeventthattheenvironmentalandradiologicalassessmentundertakenpursuanttotheRongelapWorkPlandemonstratesthatthesouthernislandsofRongelapAtollarenotreadyforresettlementwithoutfirstundertakingaclean-upandremedialprogram,theRongelapResettlementProjectshallimmediatelyprepareareportforpresentationtothepartiesheretocontainingrecommendationastoclean-uprequirementsandoptionalremedialactivitiesdesignedtomakethesouthernislandsofRongelapAtollreadyforresettlement.

[Needforfurthersurveys]

7.(a)IntheeventtheRongelapWorkPlanreport(s)tobepreparedbytheRongelapResettlementProjectinaccordancewithArticleIII,Section6(a)ofthisMOUdemonstrate(s),baseduponthestandardsandcriteriahereinsetforth,

(1)thatthesouthernislandsofRongelapAtollarefullyresettleable,thesecondstageofprojectstudyshallbetheradiologicalcharacterizationofthenorthernislandsofRongelapAtoll;or,alternatively,

(2)thatthesouthernislandsofRongelapAtollarenotfullyresettleablewithoutremedialactivityand/orclean-up,evenafterconsiderationofSection5tothisArticle,thentheRongelapResettlementProjectshallimmediatelyproposeforconsiderationbythepartiesanextendedenvironmentalradiationcharacterizationnecessarytosupportthe

developmentofremedialactionsand/orclean-up,asprescribedbySection6ofthisArticle,environmentalradiationcharacterizationinsuchotherareasasRongerikAtollandAilinginaeAtollandfurther,uponcompletionoftheseobjectives,theRongelapResettlementProjectwouldproceedwiththeevaluationofthenorthernislandsofRongelapAtollasprescribedinsubsection7(a)(1).

(b)ItistheintentofthepartiestoensurethatappropriateenvironmentalandradiologicalassessmentsareultimatelyconductedofalloftheancestralhomelandoftheRongelappeopletoincludetheremainderofRongelapAtoll,AilinginaeAtoll,andRongerikAtoll.ItisunderstoodthattheseadditionalstudiescontemplatedbythissectionaresubjecttoandconditioneduponfutureU.S.Congressionalfunding.

[Resettlement]

8.RongelapcommunityresettlementwillensueiftheinitialassessmentdescribedatSection1ofthisArticleestablishesthatnoindividualresidingonthesouthernislandsofRongelapAtollandconsumingalocalfoodonlydietwouldreceiveacalculateddoseof100mrem/yearormoreofradiationabovenaturalbackgroundintheMarshallIslands.

9.OnceadeterminationofreadinessforresettlementbytheRongelapResettlementProjectismadeandaffirmedbythepartiestothisMOU,planningforresettlementandimplementationthereofshallimmediatelycommence,withthefullcooperationofallpartiesthatfundingforrehabilitationandresettlementshallbeprovidedbywayofseparateU.S.Congressionalappropriation,thefundstobetransferredfromtheU.S.GovernmenttoaRongelapResettlementTrustFundinaccordancewiththetrustagreementbetweenDOI,RMI,andRALGOVrequirementsimposedbyCongress.

10.Forpurposesofresettlement,"Rongelapcommunityresettlement"referstothevoluntaryreturntoRongelapAtolloftheRongelappeoplenowresidingonMejattoIslandandsuchothercitizensoftheMarshallIslandswhobyvirtueoftheirlandrightsinRongelapAtollvoluntarilywishtoberesettled.

11.ThepartiesrecognizethathealthconcernsmayexistformanymembersoftheRongelapcommunitybyvirtueoftheirpriorexposuretoradiation.AdditionallytheyrecognizetheneedforcontinuedradiologicalmonitoringbothofreturnedcitizensandoftheRongelapAtollenvironmentuponresettlement.Accordingly,thepartiesagreetoaddresstheseproblemsaspartoftheresettlementprogram.

12.Thepartiesalsoagreethatintheeventofadeterminationforresettlementandsubsequentresettlement,relevantrevisionsto

recommendedindividualexposurelevelsasexpressedinInternationalCommissionforRadiationProtection("ICRP")andtheNationalCouncilonRadiationProtectionandMeasurements("NCRP")guidelineswillbereviewedtoensurethatradiationexposuresaremaintainedatanacceptablelevelofrisk.

[Future]

13.Ifinthefutureapplicableradiationprotectionstandards(e.g.,theNCRPandtheICRP)aresignificantlyreducedtobelowcurrentrecommendations,orpost-resettlementwhole-bodymeasurementsindicatethatRongelapresidentsarebeingexposedtoradiationlevelsinexcessofthe100mrem/yearlimitestablishedbySection2ofthisArticle,thenthepartiesagreetoreevaluatetheindividualdosesbeingreceivedbythepopulationoranindividualatthattimetodeterminethatnoindividualisbeingexposedtoanyunduerisk,andtakesuchremedialactionasshallatthattimebedeemedappropriate.

ArticleIIIAgreementby&betweentheRongelapAtollLocalGovernmentCouncil(RALGOV)andtheRepublicoftheMarshallIslands(RMI)

TheRALGOVandRMIfurtheragreethat:

1.InordertofacilitatetheimplementationofthisMOUandtheRongelapWorkPlan,RALGOVandRMIshallestablishaseparateentity,tobeknownastheRongelapResettlementProject,whichshallserveasthecontractingauthorityforimplementationofthisMOUandtheRongelapWorkPlanandwhichshallbegovernedjointlybyonerepresentativeofRMIandonerepresentativeofRALGOV.

2.ThescientificdirectionandoperationalmanagementoftheRongelapResettlementProjectshallbedelegatedbyRMIandRALGOV,throughtheRongelapResettlementProject,toaRongelapResettlementProjectScientificManagementTeam(hereinafterthe''ScientificManagementTeam").Inadditiontohis/herdutiesandobligationsassetforthinSection3ofthisArticle,onememberoftheScientificManagementTeam,mutuallyselectedbyRMIandRALGOV,shallserveasprincipalscientificadvisortotheRongelapResettlementProject.

3.TheScientificManagementTeamshallbeselectedbyRMIandRALGOVandbecomprisedofnotlessthantwonornomorethanthreeappropriatelyqualifiedscientists.ThemembersoftheScientificManagementTeamshallbeassignedjointresponsibilityforthescientificdirectionandoperationalmanagementoftheRongelapResettlementProject,notwithstandingthattheirrespectivedutiesandresponsibilitiesundertheRongelapWorkPlanmayvary.Atleastoneofthescientistsshallhavedemonstratedexpertiseinenvironmentalandradiologicalanalysis.UponappointmentofthescientistscomprisingtheScientificManagementTeam,RMIandRALGOV

shallthroughtheRongelapResettlementProjectprovideaservicecontractforeachindividual'stermofappointment.

4.RMIandRALGOVshallutilizesuchfundingasismadeavailablebytheGovernmentoftheUnitedStates,pursuanttoCongressionalappropriation,andtheassistanceoftheRMINationwideRadiologicalStudypursuanttoArticleVI,paragraph7ofthisMOUandArticleII,Sectionl(e)oftheAgreementBetweentheGovernmentoftheUntiedStatesandtheGovernmentoftheMarshallIslandsfortheImplementationofSection177oftheCompactofFreeAssociation("theSection177Agreement"),tofulfillthescientificandtechnicalrequirementsoftheRongelapWorkPlanaswellasthereportingrequirementsthataremandatedbythisMOU.

5.TheRALGOVandRMIshallalsomutuallyestablishandcontractforaRongelapResettlementProjectScientificPeerGroup(hereinafterthe"ScientificPeerReviewGroup"),toprovidescientificpeerreviewoftheimplementationoftheRongelapWorkPlanandothertechnologicalaspectsoftheconductoftheRongelapResettlementProject.TheScientificPeer

ReviewGroupshallbeavailableforconsultationtotheScientificManagementTeamasnecessarytoexecutetheRongelapWorkPlan.TheRALGOVandRMImayuponmutualagreementchangemembershipontheScientificPeerReviewGroupasresettlementproceeds,andneedsdictate.

6.(a)TheRALGOVandRMIshallchargetheScientificManagementTeamwiththeresponsibilityofprovidingthefollowingreports,inbothEnglishandMarshallese,totheRongelapResettlementProjectestablishedpursuanttoSection1ofthisArticle:

(1)OnorbeforeMay1,1992,apreliminaryreportonthereadinessofthesouthernislandsofRongelapAtollforresettlementinordertopermitthepartiestodecidewhethertopursuethestudyoptionsetforthatSection7(a)(2)ofArticleIIofthisMOUinpreferencetotheoptiondescribedatSection7(a)(1).

(2)UponconclusionoftheRongelapWorkPlan,acomprehensivereport,inbothEnglishandMarshallese,shallbepreparedontheradiologicalconditionsonRongelapIslandandthesouthernislandsofRongelapAtoll,pursuanttosuchrequirementsandsuchschedulesasmaysubsequentlybedeemednecessarybyRMIandRALGOV.SaidreportshalladdresseachcomponentoftheRongelapWorkPlan,anynecessaryandappropriaterecommendationsfollowingtherefrom,andshallinclude:asummaryofstudyresults;dosetoinfantsandchildren;doseassuminga"localfoodonly"dietascomparedtoa"realisticdiet"thatincludesimportedfoods;anddoseduetoplutonium.

(b)UponconclusionofsubsequentstagesoftheRongelapResettlementProject,comprehensivereportsshallbepreparedpursuanttosuchrequirementsandschedulesasmaysubsequentlybedeemednecessarybyRMIandRALGOV.

7.UponreceiptofaScientificManagementTeamreportpursuanttoSection6ofthisArticle,theRongelapResettlementProjectshallprovidecopiesofsametotheScientificPeerReviewGroupfor

review,commentandrecommendation.ResultingrecommendationsoftheScientificPeerReviewGroupshallbeformallyacceptedorrejectedbytheRongelapResettlementProject.

8.RALGOVandRMIshall,throughtheRongelapResettlementProject,forwardanyreportreceivedpursuanttoSection6ofthisArticletothepartiestothisMOU.ReportsforwardedtotheDOE/ES&Hshallbeaccompaniedbyanycommentsand/orrecommendationsthereonreceivedfromtheRongelapResettlementProjectScientificPeerReviewGroup.

[Assuranceoffuturefunding]

9.RALGOVandRMIherebycommitandpledgetooneanotherthatintheeventthefindings,conclusionsandrecommendationsresultingfromtheRongelapWorkPlanwarrantadditionalU.S.Congressionalfundingforfurtherstudies,clean-upandremedialprograms,

and/orforresettlementoftheRongelappeopletheywilldiligentlyandingoodfaithworktogethertoobtaintheadditionalCongressionalappropriationsandfundingrequired.

10.RALGOVandRMIagreetodoeverythingwithintheirrespectivepowerstomaintainthescientificintegrityofthestudiesandassessmentsundertakenpursuanttotheRongelapWorkPlan,andtoreportinwritinganycompromisethereoftotheotherpartiestothisMOU.

ArticleIV-DepartmentofEnergy,OfficeofEnvironment,SafetyandHealth(DOE/ES&H)

TheDOE/ES&Hfurtheragreesthat:

1.TheDOE/ES&HshallcooperatewithandsupporttheRongelapResettlementProject,specificallytheRongelapWorkPlan,asrequestedandtotheextentfeasible,byprovidingwheneverpossibleduringtheexecutionofitsroutinebiannualenvironmentalmonitoringmissionssuchlogisticalandothersupportasismutuallyagreed,thatwillassisttheRongelapResettlementProjectintransportingnecessarypersonnelandequipmenttoandfromRongelapAtoll.

2.SubjecttomodificationsasthepartiestothisMOUmightinthefutureagree,andCongressmightsubsequentlyendorse,DOE/ES&HshallcontinuetheconductofitsbioassayandmedicalmissionsfortheRongelappeopleduringandafterresettlementofRongelap,pursuanttoSection103(h)(1)ofPublicLaw99-239.

3.CopiesofreportsreceivedpursuanttoArticleIII,paragraph8ofthisMOUshallbetransmittedbyDOE/ES&HtotheNASScientificPeerReviewGroupforreviewandcomment.

4.TheDOE/ES&Hshallgivedueconsiderationtotherecommendationsofitsscientificpeerreviewgroup(NAS).

DOE/ES&HshallalsoassureallcommunicationsandrecommendationsbytheNASscientificpeerreviewgroupareforwardedtoRALGOVandRMI,fortransmittaltotheRongelapResettlementProjectScientificPeerReviewGroup.

5.UponrequestbytheRongelapResettlementProjectand/ortheRongelapProjectScientificManagementTeam,DOE/ES&HshallfurnishrequesteddatarelevanttothesuccessfulimplementationandcompletionoftheRongelapWorkPlantotheRongelapResettlementProject.

6.TheDOE/ES&HagreestoconductitsRongelapAtollscientificactivitiesandstudiesinamannerbestcalculatedtocomplementandsupporttheRongelapWorkPlanandtheRongelapResettlementProject.Tothisend,DOE/ES&HshallregularlyconsultwiththeRongelapResettlementProject,theRongelapScientificManagementTeam,andotherappropriateRALGOVandRMIrepresentativesastoplannedandongoingDOE/ES&HorDOE/ES&H-contractedprojectsandactivitiesrelatedtoorotherwiseaffectingRongelap.

7.TheDOE/ES&HshallprovideormakeavailabletoRALGOV,RMI,theRongelapResettlementProjectand/ortheScientificManagementTeam,withoutcharge,requesteddeclassifiedinformation,documentsanddatainDOE'spossession,orunderitscustodyorcontrol,concerningpastatmosphericandterrestrialmeasurementsrelevanttotheresettlementoftheRongelappeople.Totheextentifanydocumentsofestablishedrelevancearefoundtobeclassified,DOE/ES&Hshall,uponrequest,immediatelyinitiateaclassification/declassificationreviewinordertoensure,tothemaximumextentpossible,fulldisclosureofallinformationrelevantandnecessarytotheRongelapResettlementProjectandsuccessfulcompletionoftheRongelapWorkPlan.

ArticleV-RongelapAtollLocalGovernmentCouncil(RALGOV)

TheRALGOVfurtheragreesthat:

1.AssetforthinArticleIIofthisMOU,RALGOVagreesonbehalfofthePeopleofRongelapthatiftheinitialenvironmentalandradiologicalassessmentsoftheareasdescribedinSectionIofArticleIIestablishesthatnoindividualresettlingtothesouthernislandsofRongelapAtollandsubsistingonalocalfoodonlydietwouldreceiveanannualradiationdoseexceeding100mrem/yearabovenaturalbackgroundorwouldbeincidentallyexposedtoconcentrationsoftransuranicsinthesoilinexcessoftheprescribedactionlimitof17pCi/g,Rongelapcommunityresettlementwillensuewithoutconsiderationformitigation.However,considerationmaybegivenbyRALGOVtoadditionalpotentialmeasures(i.e.,applicationoffertilizers)toreduceindividualandpopulationradiationexposurestotherenamingpopulationfurtherbelowthe100rem/yearlimit.

2.RALGOVshallsupportthetimelycompletionoftheRongelapWorkPlanthrough:

(a)MakingtheRALGOVMembersavailabletoconferwiththeScientificManagementTeamuponrequest;

(b)Securinganynecessarypermissionsforaccess,entrance,andtheconductoftheRongelapWorkPlanfromindividualsthatmayberequiredsothattheRongelapResettlementProjectcanundertakeandcompleteallprojectfieldwork;

(c)ServingasaliaisonbetweentheScientificManagementTeamandtheRongelapcommunityatlarge;

(d)ProvidinglocalpersonnelandcommunitysupportasnecessarytoaccomplishtheobjectivesoftheRongelapWorkPlanandanyforthcomingapprovedactivitiesrelatedtoresettlement.

ArticleVI-RepublicoftheMarshallIslands(RMI)

RMIfurtheragreesthat:

1.TheRongelapResettlementProjectandRongelapWorkPlanshallbeundertakeninconjunctionwiththeRMINationwideRadiologicalStudyconductedpursuanttoArticleII,Section1(e)oftheSection177Agreement.

2.RMIshall,uponreceiptoffundsfromtheDOI/OTIApursuanttothisMOU,assuretheavailabilityofthesefundstotheRongelapResettlementProjectwithinfive(5)businessdaysofreceiptthereof,pursuanttothetermsandconditionstobesetforthinaseparateagreementtobeenteredintoandbyandbetweentheRongelapResettlementProject,RMIandRALGOV.

3.RMIassuresthatitwillcomplywithallapplicableU.S.Federallaws,regulationsandrequirementsastheyrelatetotheapplication,acceptance,useandaccountingoffundsprovidedpursuanttothisMOU.

4.AnSF-270,RequestforAdvanceorReimbursement,willbesubmittedbyRMItoDOI/OTIAforreleaseordrawdownoffundsonaquarterlybasis.SaidRequestsshallbemadeinconsultationwith,andpursuanttoinstructionsreceivedfromtheRongelapResettlementProject.

5.AnSF-269,FinancialStatusReport,willbesubmittedbyRMItoDOI/OTIAquarterly.

6.RMIshallprovidecopiesofallFinancialStatusReportsandRequestsforAdvancesorReimbursements,andanyotherreportsrequiredpursuanttothisMOU,theRongelapResettlementProject,whichshallinturnmakesamavailabletothepartiestothisMOUonaquarterlybasis.

7.UtilizingthefundsmadeavailabletotheRMIGovernmentpursuanttoArticleII,Sectionl(e)oftheSection177Agreement,theRMINationwideRadiologicalStudyshallcontributecertainofitsservicestotheRongelapReassessmentProject.

8.RMIistoassuretheclearingandmaintenanceoftheairrunwayonRongelapIslandduringthecourseoftheRongelapResettlementProjectsufficienttopermitairtraffictoandfromRongelapIsland.

ArticleVII-DepartmentoftheInterior,OfficeofTerritorialandInternationalAffairs(DOI/OTIA)

TheDOI/OTIAagreesthat:

1.TheDOI/OTIAshalltransfertotheRMItheappropriateportionofsuchfundsasareappropriatedbytheUnitedStatesCongress,pursuanttotheFY1992AppropriationAct(P.L.102-154)fortheDepartmentofInteriorforthepurposeofimplementingtheRongelapResettlementProject/RongelapWorkPlan.

2.TheappropriateportionoffundsspecificallyappropriatedbytheU.S.CongressforthepurposeofimplementingtheRongelapWorkPlanshallbetransferredtotheRMIonaquarterlybasispursuantto,anduponreceiptbyDOI/OTIAofaquarterlySF-270RequestforAdvanceorReimbursement.

3.CopiesofallfinancialstatusreportssubmittedtoDOI/OTIA,andanyotherreportsrequiredtobesubmittedtoDOI/OTIAbythisMOU,shallbeprovidedonatimelybasistoallpartiestothisMOU.

ArticleVIII-AdditionalAgreements

Allpartiesfurtheragree:

1.TheRongelapResettlementProjectshallbeinitiatedonoraboutMarch1,1992,orassoonaspracticableafterfundingismadeavailablebytheUnitedStatesGovernment.ItistheunderstandingandintentofthepartiestothisMOUthattheRongelapResettlementProjectshallconcludeitsmandateandsubmititsfinalreportpursuanttotheRongelapWorkPlanandthisMOUonorbeforeApril1,1993.

2.ThisMOUshallremainineffectpendingcompletionoftheRongelapResettlementProject.ThisMOUmaybeamendedbythemutualconsentofthepartieshereto.

3.ThisMOUshallbegovernedandinterpretedinaccordancewithapplicablelawsoftheUnitedStatesandtheRepublicoftheMarshallIslands.IntheeventofdisputewithrespecttotheinterpretationorexecutionofthisMOU,thepartiesagreetointhefirstinstanceseektoresolvesuchdisputethroughfoodfaithnegotiationsbyandbetweenthemselves.Shouldsuchnegotiationsfail,resolutionofthematterindisputeshallbegovernedbytheConferenceandDisputeResolutionsprovisionsofTitleFour,ArticleII,oftheCompactofFreeAssociation,althoughnothingcontainedthereinshallbeconstruedasabartodirectandimmediateparticipationbyRALGOVinanyconferenceordisputeresolutionactivitiesthereunder.