First attempts at validation of radiation exposure of the population along the Techa River, southern Urals

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First attempts at validation of radiation exposure of the population along the Techa River, southern Urals

K . K tinig

a,

S. M undigl

^b,

I. Win kelmann

b,L.

H ornunga

&

W . Burkstt'

Measurements on environmental samples

In 1992 an d1993,theBISorganizeda com parative measurement program me (2) together withthe

two Russian environme ntal labo ratories men- tio n ed above.In 1992, these inter-cali bratio n and comparisonmeasure me nts fo cused on the90Sr ra- dion uclide, and in 1993 on the identification of plutonium isotopes and 137Cs. In 1992, about 70environ me ntal samples were taken and ana- lysedfor their 90Sr conten t. Fewer samples (o n ly 22)were analys ed for pluto niumin 1993 be cause thesamplesrequired moretime-consu m in gprepa- ration . All these samples were also analysed for 137Csusinggamma spectrometry.

In 1992,the Gennan Federal Olli ce for Radia- tion Protection (Bun desamtfur Strah lcnsc h utz or HfS) began measuremen ts in the area near the Techa River, which was extensivelycontaminated with strontium-90 from waste disp ose d by the MAYAKnuclear fa cili ty (Chelyabinsk-65) , mainly betwe en 194 8 an d 1952. The village popu la tio n livingdownrivercontinued to usetheTech aRiver as a source of drinking-water. The measuremen t campaign was focused mainly 011 90Sr measure- men ts pe rfo rmed on parts of theaffec te d po pula- tion,To carry outthese measurements,a special mobil ewhole-bo dycounter ,capableof measuring the con tent of 90Sr/90y in skull bone, has been devel oped .The purpo se of whole-body measure- men tswastocontribute toananalysisof the radio-

"logical situation and to provide the public with

relev antinfo rmatio n,

Environmental samples were specifica lly col- lectedfromareasaffec ted by thelargeradioactive releases intothe Techa River,startingin1948.So il, sediment,water,milk,po ta to es and fishwe re divid- ed into 3 aliquotsand indepen d e ntlyanalysed for 90Sr, 137Csan d plutonium isoto pes bythe 3 insti- tutesinvolved,Le "twoRussianenvironmen tal laborato ries - MA):J\KExperimental Research Statio n (ONIS) an d the Urals Resea rch Cen tre for Radia- tion Medicine (URCRM) - and the German BIS.

After rad iochemicalprepara tio n,stan dardsamples were also independently analysed by the Rnssian and German labora to ries for inter-calibratio n of techniquesandinstru ments.Theaim ofthispart of the progra m me was to validate the large da ta base of Russian enviro nme ntal measurem ents whic h have been collected in thisreg ionsince the early1950s.

90Sr kBqlm' _ 37 000.0

_ 3700.0

_ 185.0

_ 18.5

, . I 3.7

I

~

010 20 30 4050km

! , ! ! , ,

•

Artemovskij

Introduction

Invi ewofthesuccessfu lcaesium- I37 (137CS)mea- suremcntsill the vicinity of ChernobylbyGerman scientists (1), the Russian State Co mm itteeforthe Remedi ati on of the SocialConse quencesof Cher- nob yl and of OtherContaminationsand the Ger- man Federal Ministry for Environ ment, Nature Protec tion and NuclearSafe ty (BMU) agreed tha t German aidwouldbe pro vided particularly for the souther n Urals region where the environmental co n tamination was caused bythe Soviet nuclear weaponsprogram me in the late 1940s(F ig.1).

Fig.1

Mapof the contaminated region in thesouthernUrais (1957 accident)

Cartedela contaminationenDuralmeridional (accident de 1957)

aFederalOfficeforRadiationProtect io n.Instituteof Radiation Hygiene.Oberschleiflheim,Germany.

UFederal Office for Radiation Protection. De partm ent of RadiationProtection,Berlin,Germany.

<,

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52 Rapp.trimest.statist. sanit.mond.,49(1996)

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Intercalibration ofradiochemical methodsand measuringinstruments

The first ste p in this programm e was the inter- calibratio nofradi oc hem ica l me th odsandmeasu r- ing instru ments. For that purpose, the BfS pre- pared sa m plesof plutonium isotopesan d90SI' and 13iCssou rces,each with different activities, bydi- lut ing stan dard so lutio ns. These samples we re tre a ted like envi ronme n ta lsam ples:they were an a- lysed afte r radi och em ical pre p a ra tionbythe institute sinvolved.Fig.2 summar izes the de viat ion sof me asured acti vity conc e ntra tio ns fro m the cert i- fied values. The maximum de viation was abou t 15% .Theradi o ch e mi calme th ods and the measuring instruments pro vid ed com pa rable results re- garding the rad io nuclides. Note, however, that there were nopotentialco n fo u nd e rsin the se sta n- dard sam ples,as wo uld hethe casefor enviro n me n- talsam ples.Therefo re,the main part of the co m- pariso n pro~ramm e hadto fo cus on the analysisof environ men talsam p les,i.c.. so il,sed imen ts,water, milk,po tat oe s andfish.

Comparisonprogramme forenvironmentalsamples In the main pa rt ofthe comparison pro gram me, samp les of soil,sedimen t,water,milk,po ta to e s an d fish were collec te d mainlyatMus lyum ovo.avillage of about 4000 inhabi tants on the banks of the Tec ha Rive r. These env iron me n ta l sa m ples were split into thre e aliquo ts an d in de pen den tly an al- ysed tor 90SI',l:nCsan d plutonium isoto pes by the institute sinvolved.

Fig.2

Comparison ofstandardsolutionspreparedbythe Bundesamt fur Stralenschutz

Comparaisonde solutions standardsprepareesparleBundesamt iur Stralensch utz

1.15 905r 137Cs Pu

1.1 •

.

1.05

. ^.

•

0 •

~ ^1-^{- - -}^- ^- ^-^I- ^~^-

- - - - -

0.95

. ! ~

0.9 : •

,

¥

0.85

. .

0.8

:

ONIS BrsURCRM ONI5 815URCRM ONIS BIS UACR M

Key:

ONlS:MAYAKExperimentalResearchStation-Stationexperimentale derechercheMAYAK.

Bfs: BumdesamtfUrStralertschutz.

URCRM:uraisResearchCentreforRadiation Medicine.-Centre de recherche surla medecmeradiologiquede I'Dural.

Note:Measured activity dividedby calibrated activity(A/AO)isgiven . - On donne t'activiternesu ree divisee parractiyite caltbree(AlAO).

Wld hlth,taUst. quart..49(1996)

Soilvalues inare as acce ssible tothelocalpop u- lation re ached up to 190Bq/ kg at Mus lyumovo which is some dista n cefrom the TechaRive r. The correspon di ngvalues fo r 13iCsan d pluto nium isotopes were460 Bq/kg an d 14Bq/kg ,resp ectively.

The situ a tion changes rap idlyas one approaches the Techa River, which todayis accessib le to the local po pulati on. Soil sam p les take n from the Tcchu flood p lain are conta m ina te d with up to 8000Bq/kg of 9OSr , 25000 Flq/kg of mCs and 13Bq/kg ofplutonium iso tope s.Tccha sed im e n t con tai ned 30 Bq/kg of plut onium, 40 000Bq/kg

of1:l7Csand 600 Bq/kg of 40Sr.Tccha wa ter, how-

ever, showed lower level s of conta mina tio n with OAFlq/kg of plutoni um , 18Bq/kg of90Sr an d OABq/kg of137(;s.The resu ltsof the co mparative me asu rem entsof env iron m e n talsam plesare su m- ma r ized in Table1.

Foodproducts containe dgenerallylowlevels of radio acti vity (Table 2).There were onlya few sa m- ple sthat showedelevate d levels ofradio acti vity an d most of them we re tak en in the vicin ity of the Tccha Rive r. Milk fr om private farms in Muslyu - movo con ta in e d upto 25Bq/kg of90Srcompare d to I to 5fiq/kg measured in milk sa m ples from othervillagesandfrom sta te dailycom pan ies. The highly 90Sr-co n taminated milk comes fro m cattle that grazealo ng theTe cha Riveran don theflood- plain .The state dairycom pa nies, howeve r, collec t milkfrom diff e r entlocati ons an d theretore the se values do not show local effects. Fish also con- tain ed high sp e cific 90SI'activities.In 199~~, a sample analysis revealed a specific 90Sr activity of 330 Flq/kg in fish mea t and 930 Bq/kg in fish bon e s. Plutonium ana lyses of milk samples per- for medin1993 showed no activityabovethedete c- tionlimitofO.Ifig/I.Spec ific137Cs-aetivityin milk ranged from 1.2to 7.3 Bq/kg. Po tatoe s from Mus- Iyumovo con ta ined 13Bq/kg an d fish43 Bq/kg of 137Cs.Drinking-wa ter contains on lyafewmillib ec- qucrcl (3).

In 1990, Trapezn ikov et al. (4) perfo rm ed me asurem ents on sa mp les taken at 4 different sitesalong the Techa Rive r. Theyconce n tr a te d their eff o rts on the analysisof Techa River wate r, sed imen t an d hiota (water plants) an d fou n d results com parable to the measur em ents carried out by BfS , URCRM an d ON1S. The com pa r iso n of envi ro n men tal samp les showe d a fair level ofcons istencyamo ng th e 3ind epen - dent laboratori e s. Contrary to the expe r ie nce of the Intern at ion al Che r nobyl Pr o je ct there was no overestimation of !XlSr activi ty in the Russian ana lyses . For ana lysing plu to ni u m, the Russian laborato ri e s separa te pluton iu m iso- to p e s rad io-c he m icallyand me asur e gross alpha emitters.This method still includ e salph a-parti- cle-emitt in g impu ri ties.The refo re,the Russia n re sul ts so me t imes overestimate the values ob- tained byBfs usin g alp ha spec tro me try.

53

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Table1

Comparativemeasureme ntsof Pu,90Srand137CSin samples from theTechaRivernear Muslyumovo(1992:9OSr:1993:Pu and137CS)

Tableau1

Mesurescomparatives du Pu,90Sret137Cs dans desechantillonsprovenantde la riviereTechapresde Muslyum ovo (1992:90Sr:1993:Pu et137CS)

Specificactivityin Bq/kg- Aclivite soecitqoe enBqlkg

sample-Echantillon ONtS URCRM BIS

Pu 90S, t37Cs Po 90S, 137Cs 238pu 239pu 90S, 137Cs

Techawater- Eau de laTecna 0.04 7.4 0.59 0.016 17 0.56 0.08 0.28 18 0.41 Techasediment-

seolmemsde laTecha 51 610 37000 44 420 39000 0.95 33 610 40000

Soil from Techafloodplain: - Solprovenantdu litmajeur

delaTecha:

First sample:- 32 4700 26 000 28 5600 24 000 0.23 9.7 5200 25000 Premier echantillon:

0-10cm Secondsample:- Deuxlerne echantillon:

0-5cm 19 7100 18 000 14 1600 0 18000 0.50 12 8600 21 000

5-10cm 15 6200 21 000 11 12000 21000 6700 25000

10-15cm 8.4 5700 3300 4.4 9600 3300 0.50 60 8200 3900

15-20cm <4 5500 280 4.1 9600 320 0.23 1.7 6400 290

20-25cm <4 3900 300 3.0 7900 310 0.65 0.51 4500 350

25-30cm <4 340 1100 4.0 790 1 100 0.16 1.2 390 1100

Soil from a soccerfield- 7.2 46 240 3.0 45 300 0.36 1.3 <110 190

Solprovenantd'unterrain de football

Soil from ameadowabove 11 190 460 5.6 170 340 0.76 13 150 460

TechaRiver-Sol provenant d'une prairieau-dessusde

lariviereTecha

.Measurements o f incorporatedradi onuclides

In 1993,investigat ion softhe exposureof thepopula- tion along UIC Techa River to radiation included a whole-bodymeasureme ntcam paign.Accordingtothe history of exposure the nuclide of main interest was thebo n e-seekingfission prod uct90SI'. The40K(po tas- sium-40) and 137Cs nuclideswere alsomeasured.In orde r to cond uctwhole-bodyinvestigationsat theset- tlemen ts ofinterest,i.c., along the TechaRiver,andto det ermin e the body burden of 90SI'with an in vivo device,a new,mobile system for detecting 90Sr and gamma-ray-emittingradio nuciideswasdeveloped.

Measurementtechniquesandcalibrations

Direct, in vivode tectio n ofincorporate d radio n u- elidesis limited normallyto nuclid es wh ich emit gammarayswithsufficien tlyhigh photonenergies.

The measurement of the pur e beta-ray-emittin g

90Srwith an in vivodevice wasbasedup tonow on thedetennin a tion ofbrcmsstrahlung,whic hispro- duced hythe slowing down ofbeta particlesin the tissues.However, theyiel d of this unpea ked radi a- 54

tion is very low, an d, therefore, one has to use a wh ole-bodycounter with heavysh iel ding.

As the main in takes of 90SI'took place ma u y decad es ago,onlycorticalbone stillcontains mea- surab leamo untsofincorporated9OSr.The refore,if the amountof th is nuclid e in the skull bone could be measured,the totalbodyburden could be esti- mat ed. Fortun ately, the thic kness of the scalp (in the r.mgc 0[3 to 8mm ) allows thefastbe tapa rticles of goy(maximum en ergy 2.28 MeV) to pe n e tra te th ispartof the skinwith ayield high enoughto allow direct counting of these particleswith a shield ed propo rtion al be ta coun ter. In summary, thisnew, mobile,invivocounter consists ofadetectorsystem tocount thebeta particlesleavi ng the scalp,a ger- maniumdetectorlocated at the backofthe skullto analyse bremsstrahlung resulting from these beta particles andgamma radiation of otherradionuc lid- cs,anda seco ndgerm an iu mde tec tor system direc t- ed to the lowerpartof thetorsoto measurerad io nu- elideswhich arc distributedhomogeneously in the body.All these detectorsare placedarou nda chair Raw trimest.statist sanit.mond.,49(t996)

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Table 2

Comparativemeasurementsot90Sr and137Cs infood samples,1992 and 1993 Tablea u 2

Mesures comparatlves de90Sr et13'CSdansdes echantillonsallmentalres(1992 et 1993)

Specificactivity inBqlkg-AclivitesoecmcueenBq/kg

Samplingsite- Sample-Echantilfons ON'S ^U^RCRM BfS

Lieu d'echanttttonnaqe "Sr ^137C^s "S, ^l3lC^s "S, ^131Cs

Muslyumovo Fish - Poissons:

meat - chair 330 43

bones-aretes 930 43

Muslyumovo Drinking-water- <0.10 <0.10 025 <0.10 <0.10 Eau de botsson

Muslyumovo Potatoes- Pommes deterre 3.0 29 2.2 70 6.2 13

Muslyumovo Privatefarms- Fermes privees

1.milksample- 1.0 3.8 0.70 5.2 1.5 <1

ecnantdtondelalt

2.milksample- 9.5 12 9 13 25 7.3

echantillondelait

3.milksample - 1.0 6.7 1.1 2.4 1.2 <1

echantiltondelait

4.milk sample- 5.6 13 6.6 4.3 7.8 <1

e cnannnon

delait

5.milksample- 0.95 2.1 1.0 2.4 <6.3 3.1

echantillondelait

Statedairycompany- 0.31 3.6 0.1 0.9 <2.6 Societelaltiere d'Etat

,

"

1 1

1

J lj ,

~

o

5 10 15 20 25 30 35 40 45 50 URCRMresults90S'(Bqlk)-

Result,ls ducompteurdeI'URCRM,90S '(BQ/k) FIg.3

Comparisonof internaldosesof 90Sr,usingthewhole-body counterat URCRM andtheGerman mobile coonter

Cornparai sondesdoses Internesde90Sr,

a

I'alde ducompteur corpsentieraI'URCRMet du compteurmobileallemand

ung of90Sr^j^90y' The comparison of the measu re- mcn rs of54 persons ateach device sho ws a fairly goodtrend (r

=

0.77) ,whic hisre markable conside r- ingthetwo differentanalyticalapproaches(Fig.3).

50 - , - - - -- - - ,

-19~

~'"

g-=-

40

=

^~O

",0>

~ti~~ 30 E~

8:

~E 20

~o~~

~ ~ 10 EO.

<;;E

"'8 with a sha dow-shield ill front of the pe rson. To increase the sensitivity ofthe dete ctor s which arc directed to the skull,a\'(:to-Syst CIllwasinstalled addi- tionallytu reduce the background counts (5). For the calibratio n of this measuri n g system a special head phantom (G.La u rc r, New York University Medical Centcr) with removable scalp and skull bo ne wasused.A set of piecesofpaperwith thre e differen t amounts of90SI' ac tivity could he placed insideandoutsideoftheskullboue.

The real thick ness of the scalp of the people under investigation was measured in vinowith an ultrasonic device. For a mean scalp thickness of 4mm the detection limit was dete rmine d to be about 900Bq of9nSr (in equilibrium with901') for the total skeleton (measuring time 30 min utes).

Forthe calibrationofthe nuclides40Kand Hies a

"standard bo ttle phantom"wasused.

Inter-comparison measurementswithURCRM Before starting the measurements at the Tccha Rive r settlements, a compariso n with the whole- bodycounter (type SICII 9,1) at th e URCRMwas ca rrie d out(6j. Th is coun terscanne d thepersonand usedphoswic h-dctcctorsto analyse the brem sstrahl-

Wldhffh starlsl.quart..49(1996) 55

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25,--- - - -- - - , Fig.4

Mean"SractiVityamonginhabitantsofsouthern IIrals Activifemoyennedu"'Srchezleshabitantsde1'0uraJ mendional

Results anddoseassessments

The resultsof the measurem entswith the whole- body co unterco rresponde d to the findingsofthe Russian investigatio ns.The 905r body burden as measured now ishighly depen den ton age at the time of intak e,especiallyforpeople 15 to 20years old at that time (Fig.4) .The notable diffe re nce in

the mean total body activity of 90Sr tor the two settle me n ts can also be shown (3). Incorporated 137Cswasfound onlyininhabi tan tsofM uslyumovo indicatingon-goingincorp orationof fission products,

To estimate size ofdose arising fro m inte rnal exposure to incorporated 90SI' the intake in the years 1950 to 1952 can be regar d ed as acu te.Ac- cord ing toICRP67(7),ameasuredbodyburdenof 10 kBq in 1993fo rpeopleolde rthan 60years ,i.e., in Muslyomovo,is the remainingactivity ofan in- takeofabo u t4 MBq.Thiswillre sultinaneffec tive do seofO.11Svfo rpeo plenow older than 60years.

Thesam e intake assum ed for personsnow55ye ars oldrep rese nts aneffective doseofabout 0.32Sv.In this case, the dose to the red bone marrow am o n nts to approximately2.0Sv,and the dose to the bonesn rfaceto 7Sv.

Conclusion

The inter-compariso n exercisesbe tween Russian and Ge rman institutes showedthat the differenc- es betwee n the mea sured values are not greater than a factor of two. This is true not only for enviro nme n tal and food samples, but also for incorpora ted 90Sr in peop le.The findingsof the Russian investigation s on the co ntamination of the Techa Riverfloodplain and the time pa tt ern of⁹⁰Sr intakecould beconfi rme d .Therefore, the German inve stiga tionsareastep towards an inde- pendent valid a tio n of theen ormousdat a baseof the Russian institutes on radiation ex po sure of the population alo ng the Techa Rive r. These resu lts form the basi s for der ivin g risk coefficie n ts for contin uo usexpo sure.unlike that of Hiroshi- ma and Nagasaki.

A res earch progr amme sponsored by the German FederalMinis try fortneEnvironme nt,NalureProtection and NuclearSafety(BMU)wasconducted during1992 and 1993 in the Southe rn Urals,to providean initia l validation and comparison of results of population exposurearisingfromtherelea s eofrad ioact ivewaste from the MAYAKnuc lear facility between the years 1948 and 1967 .This programm e included investiga - tions of the contaminationof the soil,of food (milk, drinking-wate r, potatoes) and whole-body-counte r measureme nts of inhabitants of settlements at the Te cha River.The nuc lidesof interest were piutonium isotopes and thelong-livedfission products'37CSand 9OSr.Results ofthes einvestigations,particularlyin and aroundtheVillageofMuslyumovo(78kmdownstream fromthe pointofrelea seof the radioactive wasteinto the Te c ha River),areshown.These investiga tionsare a first step towa rds an inde pen dentvalida tion of the enormo us data base collected by the Russian institutes andof derivedvalues ofthedose s tothe popula- tionoftheTechaRive r.

Summary

Measurements in:- Mesuresetteciueesa:

- - .Cheiyabinsk - -- Brodokalmak - -Muslyumovo

35-3 9

Yearatbirth- Anneedenatssance /\

/ \

/

\

/

\

i \

I \

I

5 20

Measurementsof thepopulationalong theTeensRiver From Augu st to Oct ohe r 1993 abou t 650 people were measu red with the mobile whole-body counter: 250 people at the URC RM in Ch elya- binsk, 200 in Muslyum ovo an d 200 in Brodokal- mak. Special atten lion was given to measurin g people over 40 years old, to evaluate the age- dependentre tention function of905r.This group

\\'<1S heavily exposed by releases into the Techa

Riverbetween 1948and 1952.

The maincharacteristic of the two settleme nts isthe remarkabledifferen cesin theiruseofTecha Riverwater.The populat.ion ofMuslyumo vo used the Te cha Rive r as th e wate r su p p ly for all purpo ses, whereas the people in Brodok almak mainlyused wellwate r.

The group measuredat the URCRM includ ed hospital patientswith ve ry high 90Sr le vels and inhabitants of Chelyab insk, mainly younger people withlow bodyburdens.

56 Rapp.trimest.stalist.ssnit.mond.,49(1996)

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R esume

Premieres tentatives de v alidation de I'exposition aux rayonnements de la population vivant le long de la riviere Techa, O ural meridional

Pour une premierevalidationet comparaison desreset- tats deI'exposition delapopu lation due

a

^laliberation de dechets radioactifs par la centrale nucleaire MAYAK entre1949 et 1967,un prog rammede rechercheparraine par le MinisteredeI'environnement,dela protectionde la natureet de lasOretenucleaire(BMU) de l'Allemagne tederale a ete entreprisen 1992 et 1993dans l'Oural meridional.Ce programmecomprenaitdesenquetessur la contamination du sol, de la nourriture (lait, eau de boisson,pommes de terre) et des mesurescorps entier des habitants vivant le long de la rlviere Techa. Les nucleide spresentant un interst partlculier etaient des isotopes de plutoniumetdes produits de fission a vie longue 13lC S et 9OSr.Les resultats de ces enquetes, notammentdecelles quiontete faites dans levillage de Muslyumovoet autour decelui-ci(78 km en aval

a

^part^ir

du point deliberation desdecnetsradloactlfs dans la riviereTecha),figurentci-apres. Muslyumovoest le pre- miervillage en avaldelarivierequin'apas ete evacue, Ces snquetes allemandessontune premiereetapevers une validation indep endante de l'enormebase de don- neesdes Institutsrusses etdes valeurs deriveesdela dose recue par la populationdela riviereTecna.

W/d hlthstsus:quart.,49(1996)

References/References

1. HilIe,R.Measurement of theradiologicalexposureof the population in the highly contaminated '.lreas around Chcm obyl, in: l,ehnlahre nad, Tsdtenwb'Jl, eine Bilan:;., Munich,March 6-7,1996,proc eed ings,in press.

2. Winkehn ann, I. et al. Imercomp arison and validation measurements of radioactivity in Southern Urals areas contaminatedbyreleasesintoTech a RiverandbyKysthym

fallou t ,HealthphysicJ(fo r thc omi n g)

3. Umweltrnd ifJflktivitiit

mm

Strahlenbelm/tl1lg,jabresteridu 199 1.

herau.sgt'gf!hen vmnlhmdesministerjii rUmueu;Naturschutzund RmkwJichm uit,Deusduand.Boon,199 1[inGerman ] 4. Trapcznikov, A.V.et al. Radioactivecontamina tionof

theTechaRiver,theUrals.Health physics65(5 ):412-488 (1993)

5. Wahl, W. et al. Combined beta/gamma-radiation and bre mssrra bt u ng monitorfor measure mentsof in corpo fated radio nuclides-the!l°Srin-vivoco unter. Nuclearinstruments andmethodsinphysicsresearch(fo rthcoming)

6. Kozheurov,V.P.SICH-9.1-a uniquewhole-bodycoun ting systemformeasuringSr-gOviabrc mssrrahl ung: themain resultsfrom alon g-terminvestigation of the Tccha River populatio n,The scienceoJ the total mninmment 142 (special issue : Radiation exposure in the so uthern Ur al s): :J7-48 (1994).

7. Age-dependen tdosestomembersofthepublic fromintake ofradion uclides.part2(1994), Annals oftheIr.RP23(3/4}, ICRPpublicationNo. 67

57

I I

I I I '