I .VI S-rnJ — 1 2M2

Isotopeseveryday

life

Isotopes ineveryday life

International Atomic Energy Agency

Vienna, Austria

Table of Contents

Introduction. 2

Food and agriculture 4Crop production 6Mutation 8Animal production 111Insect control 15

New World Screwworm 17Fruit fly 17Tsetse fly 17;F-1 sterility 18Other technology 18]

Food preservation 1f

Human health applications 2;Nuclear medicine 2;Radiopharmaceuticals 2Nuclear cardiology 2.In vitro diagnostic methods 27Radionuclides in the treatment of disease 2i

Therapeutic nuclear medicine 2{Teletherapy 2lBrachytherapy 2:

Dosimetry 30Radiation biology 31Nutrition 31

Industry 32Radioisotopes as tracers 34Radioisotope instruments 36

Gamma radiography 40Autoradiography 41Neutron radiography 41Smoke detectors 42Light sources 42Radiation in manufacturing 42

Hydrology 44Applications 46

Geology, geochemistry, geophysics, and dating 52

Environment 56Air 58Water 58Soil 59

Basic scientific research 60IAEA activities in co-ordinated research programmes 63

IAEA involvement 64

Introduction

The first question which comes to one'smind when looking .ti ihc liile »>}' ihi-»

booklet is WHY a special brochure on ;iscientific tool or ;i teclinique is neccssar\.Bool luces are also ;i lool. bul no one luiswrillen ;i booklet ;iboul I he use o( bootlaces. What makes isotopes (or nudities)si) special lhal lhe_\ deserve imicli work.elTorl. and appreciation.'

Isolopes represent a tool which cando certain jobs better, easier, quicker, moresimply, and cheaper than competitivemethods. Some measurements could notbe done at all wilhoul the use of isolopesus there are no allernalive methods avail-able.

Isolopes are ideal tools for use inanalysis; a single atom can be detectedwhen using radioactive isotopes, as com-pared to chemical methods in which thedetection limit ol'an clement is enhanced a

million limes. .Stable isotopes also can bedelected v>uh great accuracy nowadays;although not quite with the same sensiiiv itvas radiation emi i i ing I radioacl i \ e )i sol ope.

Mosi imporlaj I. especially inbiological and medical work, is thatradioisotopes can be located during abiological process. The functioning olcer-lain glands also can be checked. h\ firstadministering a small amount of aradioisotope and then lollou ing the palh ofthis compound in the body simply bymeasuring the radiation from the outside.Tor people who nui\ uorrv about lliesgsmall amoimisol radioaclix ily. it should beremembered lhal e\er\one constantly eat̂potassium in their food, which is in itselfslightly iadioacti\e. and will) whichanimals and humans have lived lor a lonjlime. I'or most of these applications—am

Ihcrc arc mail) there

method.

no alternativ

l.arikTsOUI'Ces.some I OOOOOOlilllCs

stronger, w liieh emit penetrating radiation,can be used as a portable \ - r a \ unit locheck welds in underground pipelines.Such soinxes also are used tor certainanalyses especially siiiied for work in iheI'iei.'. Mich as in geologv. \'er\ large sour-ces, sonic 100(1 million limes sironjicr lhanIhe aeii\ilies used as tracers, can dcsiro\haeleria or oilier spoilage organisms infood, can he used lor sierili/alion ol medi-cal sutures or s\ rinses, or can impartspecific dcsirahle properties to sonicmaterials.

As isotope sources rc l a t i \ e l \

cheap. Ihe insimmenlalioii is re;ulil\ avail-

able, and the application simple. lhe\ find

w ide ap|ilicalion in praeticalK all iickls of

IN DAY TO DAY

science and indusiiA. It is not surprisingthat Ihe importance ol the use ol iheselools. in spite ol the L'nmih ol Other newmelliods. is ste,idil\ mcieasin;_i in hoihile\ elopiuu and de\ eloped countries.

This hooklcl can do no mine thans:i\e a panoramic \ iew ol'the yreal nnmlvrand \ariel\ ordilTercnt ispesol'dails nse-lul applications. This becomes ob\ iousuhen one realizes that, lor instance, inmedicine alone, an index in a book dealing\\ iill all diagnostic and therapeutic uses olisotopes and radiation would take do/ensol'pajies: therefore. onl\ a short re\ iew ofthese tools of science in their differentfields is indicated: in some cases examplesarc given lo illustrate their operation andachievement.

t It It andagriculture

I;n agricultural research, isotopes and radiation.play a part in so many fields and in so many

ways that it is difficult to obtain a proper pictureof their enormous importance. In laboratories ofdeveloped countries, isotopes are used routinelywith an ever increasing assortment of modern re-search aids. In emerging biotechnologies, whichare used increasingly by agricultural scientists, iso-topes are a basic tool without which research in

molecular biology could not be done.

The main agricultural problems isotopes and radiation are helping tosolve are to:

• determine conditions necessary for optimizing fertilizer and wateruse efficiency, as well as biological nitrogen fixation:

breed high performance, well adapted;uul disease resistant agriculturalami horticultural crop varieties n^iniiradiation induced mutations:

eradicate or control insect pests usinginsecls thai have been radiation steril-ized or genetically altered:

improve reproductive performance,nutritional status, ami health ofanimals using radioimmunoassas andrelated techniques, as well as isotopieI racers:

reiluee post-harvest losses In sup-

pressing sprouting and coniamin-alion using radiation treatment:

reduce food home diseases and extendshell-life using radiation: and

• studv ways to reduce pollution frompesticides and agrochemicals.

Through the estahlislimenl of a JointDivision In the I AM A and the Food andAgriculture Organization (I-A()). coveringnuclear techniques in food and agriculture,activities in these defined areas could headvanced and applied in developingcountries to their immense benefit.

Crop production

Agood crop needs soil wiih adequateamounts of nutrients and moisture.

Nuclear techniques are ideal tools formeasuring the efficiency of fertilizer useby crops and for keeping a watch on themoisture content.

In modern agriculture, the use of fer-tilizers is essential to maximize cropyields: for example, a 50 percent increaseingrain yield of cereals is common in manysoils through efficient fertilization. Inorder to provide food for the constantly

increasing world population, the projectedfertilizer consumption in 2(1 \ ears' time isestimated to be 4 to 5 times greater thantoday's. To reduce the fertilizer require-ment to an absolute minimum and therebysave production costs to the farmer andreduce damage to the environment, studiesto obtain information on the relative meritsol different fertilization practices—such asmethods of fertilizer placement, times ofapplication, and types of fertilizers—areneeded. The method used to solve theseproblems requires the introduction of

6

knou n quantities ol fertilizer labelled w nilisotopes lo l l v soil al \ anoiis nines and indil lcrci i l posiiioiis. Smee llie plain doesnot discriminate Iv lueen elements trumllie labelled Icr l i l i /cr and lliose Iroin nalive soil, llie exact ainounl ol le i l i l i /e inutrients taken up bv llie plan! ean hemeasured.

Results of this research ha\e beenincorporated in agricultural practices lorcereals ami have increased crop producl i \ i l \ s i i ;ni l icant lv. reduced l e n i l i / c iuse and therein cosis and helped ilk-c m i ronmcn l hv reduc ing ma ikcd lvresidual Icr l i l i /cr in soils. Recoinineiulalions based on the results ol experiments inihis area have been adopted in I \ ( ) oriMiii/ed fertilizer programmes in manvcountries and ;jreal savings have beenreported: one counlrv usin;j these lechniques claims 10 have saved as much as I SS.Vi million per vear on mai/e crops alone.

Similar natural methods have beenadapted to ev aluale deposits ol cheap rockphosphates as an altcrnative to expensive.often imported, phosphate leri i l i /ers. andlo find the most cll icient wav lo use thesele r l i l i / e r deposits for maximum plantarovv i l l .

.\lilnuiuli niIrojien constiiuiesXO per-

cent of jiases in the atmosphere, feu plants

c m iluectlv make use ol it. However.ihioi iLih a piocess eal led b io log ica l111111 >;_• i• >i 11 x.it ion. plants are able to use themlioLien m the .i\\. I he most importanticsiilis 111tm a s\mhiosis between a plain.\i)d a h.kierumi. and has rained -jreat.mention during recent ve.iis.

l.e^unies that fix niiropei. can pro-\ule hi;jh protein lor liuinan ami animalconsumption and also increase nilrouen insoils. The w ater plant A/o l la . lor example,can derive Sll-l)() peuci i l ol its nitroiieii h\l ixat ion. .twd is valuable m providini :nitrogen to padd\ rice crops. In order toobtain max i muni henel Us iroin I his unii.|uebiolojjical process, isolopes are used lo111 id I he amount ol nil roi:eii thai a plain canl ixaudhow this can be unproved. Isotopetechnic|ues are an ideal tool to distinguishml i ouen derived from I he atmosphere, soil,and applied fertilizer.

Water is the most importantI act or lor ciop production m manv areas ofthe world. Ihe ellieieiil use ol water inirrigation s\ stems rei|iiires conlinuoiismoniioriiii; of the moisture content of soil.Neutron moisture iiauties are ideal iiistrnineiils lor ihis purpose and help soilphvsieists to make the best use of limitedwater resources. Through these methods,traditional irrigation methods an im-proved and in some cases up to 40 percentof Ihe water can be saved.

Agrochemicals

Mutation

A L'I ICtlllUial piodlh Ijon K'lk's heav l l \oil chemical Ilipills Icr l l l lA ' ls ID

hoosi production ;iiul pcslii ides lo suppress weeds and control insects. IACCCSsiu1 use i l l ' ibose chemicals harms the en\ iron mo ni as well as iho I < »< u I product.

Isotopes ae ideal lools lor siiuK inii

I hi' beliax inr. breakdown, ami residues ol

ajii ocltci i i ioals in so i l , w a k ' i . planls.

annuals aiul l lk' ir piculikls.

\s ;i ivsnll dl i lk' ir ii'-c. n IKIN Ivcnpossible in dc\ ise sak'i \ \a\s u> applsaiirck hcn i kaU and salcr lonnulal ionsu l i k l i me nioiv el lc i . l i \ o in ninlroll inL!pests (i| pidiiKiimii •_'!< iu i l l . as u i ' l l as lessliannlul in healih and the eir- lorii i ik-ii i.

For (.vnlui'k's. mankind li'K'd e\ ei \ possihlc \\n\ lo imp iou- ijiianiils and

i|i iali l\ olcrops. \a iura l eMiltuion ivsulisI'mm sponlaneoiis mulalion and seleeiionol I ho li lk'si nnilanis. The rale ol mnialion<ieenrrence can he imil i ipl ioi l h\ railiaiiontrealmeni llierel\\ aeeeleralin;-: evoluiionand iho scleclion of superior crops.

Over ihe last 50 \ears. a luimher olplant hivedinu programmes ha\e includedmula l ion induct ion wi th radiat ion orchemicals to brecxl imprnvoii crops.

Physical mutations l ike \ - r a \ s .

gamma rays or last neutrons are mosi

l'rei.|uenil\ appl ioi l ami their use has

resulted in Ihe highest number ol" im-

prov ed. mutant ci ops. The numbero l in-duced mutant derived crop \aril ies nowexceeds. 1500 wor ldwide wi th bi l l ionsol dollars added lo l am ias ' incomes an-nua lh .

Important desirable properties w hich

one max achieve b\ railialion mchkle:

IinproM-d lixl<;in<j resislancc: Theilesired properties are a reduction inplain hoijilil anil a siilier siem. whichcan v\ iihstand rain and storm.

Chiinjied muturiiif> limes: l uu l y :iiiaiiiriiii: is important to escape frost.;pests, etc.. or simplv lo make room in ]the field for other crops.

8

Increased disease resistance: IUi( i inin;j U ' IA nnpmlanl in alkinpl-. in

(k'l II'.IM.1 I hi1 use nl L'iK'iu K als whkh

;MV liM'd aiMitlsl |vs|s In prnkvl tin.'

L'II\ irnninonl.

Ini|)ii)\ed aiiidimmic eiiai aili.-rs:

I in lA.inipk'. IMHU' \ \n i i r i h.tnimi-sv

'jli '.iU'l Ink'l ;ilk i' .i'J.illlsl ! k \ n . ni

•_\'lU"l.lll\ I'v'lk'l .ul.ii'l.ihililx In . i \ . i l l

ahlv." MI I ! t I'IUIIUIIII-..

Increased \ields: i Iv \ k kl nt mamcrop \ unclics \);)\ IH'L'D I IK I .-;isi'il

muin lo l i l ;II"IL"i' imilaiimi hroL-ciini:

iisinji inn. k-ai" ioi.'hiiii|uos.

ImproMd seed tliarafleristics: Ini|H<>\ L'llicnl nl iiulNlmiLiI \allk' ipink'ill

nr nil I'link'iili. l\ikm;j ami iacllin;j

i|uahiies. in' ivikiLlmn in omkiiii: link'.

Economically important mutant

CropBarley

BeansC'aslor he;mC'ollon

GrapefruitPeaRapesectlRice

Sesame

SugarcaneSunflower

VarietyTrumpt'. TriumphDiamant. KnsialMidas(iratiiii.SanilacA runN1AB7SLumian No. 1Star Ru«b>Wasaia. Heisza. JaranStellarCalrose76. M-401Kashmir BasmaliIRAT 1.1RD6Alumna IIYuanfenti/aoAhnsanggaeKalika "Co 4-W. Co 997PervenelsCaslclpi>r/iam>. CresoCargidurox.Novosibirskaya 67SiriusMvX

varietiesCountry(iermanv.rK('SIRI KI'SAIndiaPakistanChinaUSAPolandCanadaI'SAPakistanIvory CoastThailandIndonesiaChinaKoreaIndiaIndiaUSSRItalyFranceUSSRGermanyHungary

9

Main ol the radi;ilii)ii inducedmutants have made a great impact on theincome ul the region where thev lookplace, in some cases even on [lie nationalincome. One of the earliest successes con-cerns peppermint. I he onlv source ol'pep-pcrmini oil in the I'nited Stales Mas iheMilcbam varielv which succumbed to afungus disease. Cross breeding methodsTailed lo produce disease resistant pepper-mint. Radiation techniques led to induc-tion of resistance which saved the originalpeppermint taste enjoved In millions allover the world.

Another remarkable success siorv ofapplied radiation to obtain eeonomicallvsignificant imilants was achieved in Pakis-tan. There, a new cotton nuilani wasreleased In !!ie Pakistan Atomic linergvCommission in )lJS.^. It turned out lo bethe most productive \ariet\ in ihceounr i .The cotton production in Pakistan wasroi.i!jhh doubled! It is estimated thai ihecrop value ol this nuilani durint; |ysX-ll>8y was more than L'S SI600 million.Ho\\ e\ er. not alw a_\ s does the success of amutant show so q u i c k h as in ibiscase: sometimes it takes more than adecade before the usefulness of a newmutant is fulls recoiim/ed.

In Italy, where nearly everyone eatspasta. 50 percent of pasta stems from awhat variety developed through mutation.

Radiation is used to improve plants suchas sorghum.

In China, euraordinai \ results wereachieved u ith iliis method: a certain t\pe ofrice now matures 24 da\s earlier, anotherispe has ;i 2(1 em slioner culm and in a thirdmutant a \er\ hitih protein content wasachieved 115.6 percent i. \ i i t ua l l xhundreds, if not thousands, of such benefitshave heendexeloped o\erthe last lOvearsb\ artiliciallv produced imitation in Chinaalone w here almost a tenth of the total cropacreaye is umWr mutant derived crops.

The list ol countries which have :released crop v arieties developed throughinduced mutations is impressive. There 'are more than 40 countries vv ith over 1500 jreleased mutants of which less than 10 i

10

perceni arc chemicallv induced and morethan l)() percent are induced b\ radiation.

certain!) one of the significant achieve •ments ol the "Atomic Aae".

Animal production

Mans animals give us nieal and milk.The) also give us wool anil leather

to make clothes and other products. Inmany countries ihe\ also provide fuel forcooking and powerlo cultivate the land andharvest the crops. In some countries, theeconomy and the wellbeing ol the peopledepend on this and radioisotopes are help-ing to improve results. Hou do the) dothis'.' B\:

• increasing animals' hod) weight andmilk yields ihrough heller feeds;

• improving breeding of livestock hvdetermining ihe correct stage ol thereproductive cycle through hormonemeasurements with isotopic methods;and

• eliminating diseases by producingvaccines by radiation through \-ravswhich are sate and cost effective.

Radioisolopes are used to find thebest way of feeding animals so that the)make the optimum use of available pas-tures and the b\ -products of various

agricultural industries which are normalKused to feed them, (his is done hv labell-ing feed and certain bod) metabolites vv ithisoiopes. such as carbon-14. and then fol-lowing their aclivin wiihin the animal'sdigestive system and other parts of ihehod) to determine where and him quicklvthev are broken down and how efficientlythev are convened into bodv tissues ormilk. In effect, isoiopes are used to deter-mine the nutritional value of feeds for live-stock so that the best combination ofmaterials which are potential I v available toIced them can be chosen. H\ the sametoken, if a particular feed is found not to heparticular!) nutritious, isotopes can beused to examine wavs of improv ing it. suchas bv treating it with chemicals or sup-plementing it vv ith another material so thatthe animal's a hi I it v lodigcsi it is increased.

Kotopic methods have been a: thecentre of main of the major advancesw hich hav e taken place in the past I s v ears,such as how to feed animals and increasetheir abiluv to produce useful products.One good recent example comes fromIndonesia. In this counlrv. buffaloes aiv

11

v iial ID [he production D)' lhe riLC crop aswell as providing meat, and ihe farmersneeded a heller feeding method so thaillieir ability to plough ihe land and logrowwould he improved. The problem was thatthe only materials available ID feed themwere poor quality grass anil various oilierby -produels of agriculture.

Alter using iso'.opes lo study howefficiently these materials were digesied.scientists in Indonesia were able todevelopa mulliniiirienl block lor the bul'laloes tolick. This hail ihe effect of increasing. byover 3 kg per week, the rate al which theygained weight. Feeding ihis block to theirbuffaloes had another important spin offfor the fanners: instead of having to feedthem 55 tonnes of grass to produce ! tonneof bodvn eight gain, lhey had lo feed theanimals only 10 tonnes. This was \ervmuch appreciated because the grass has tobe cut by hand and carried lo ihe animals.

Another major use of isotopes inanimal husbandry is in breeding, {•'•.•maleanimals can be bred only when theirovaries are functioning proper!) and theyare at lhe correct stage ol their reproductivecycles. These points can be checked bymeasuring the levels ol the reproductivehormones w hich control lhe aetiviiy of iheovaries tin particular a hormone calledprogesterone), using radioinimimoassavI RIAL

This technique is very simple and isalso sufficiently sensitive to measure theextremely small concentrations of hor-mones which are present in ihe animal'sblood or milk, li involves laking someblood or milk from the animal, adding itlo a tube which already lias been coaledw nil an antibody lo Ihe hormone, and thenadding a radioaclively -labelled hormone.The lube is ihen cenirifuged. the liquidcontents removed, and llie radioactivityled in the lube counted. The concentrationol ihe hormone then can be determined byreference lo the radioactivity counts insamples containing known amounts ofthe hormone.

RIA's of reproductive hormonesare used for many different purposestoday. In artificial insemination pro-grammes, they are used to check w helheranimals are being inseminated al ihe cor-rect lime in their reproductive cycles,whether llie inseminalor is conductingthe insemination properly, and lo deter-mine al a very early stage whether theanimal has become pregnant after in-semination. This can save the farmer agreat deal of money because if the animalis found not lo be pregnant, she has io bebred again at the approprialc lime ol thene\t reprodutive cycle, otherwise, therewill be a long delay between lhe birth of;successive offspring. RIA's are also;used in embno transfer programmes to I

12

Better feeding and management improves reproduc-tive efficiency in buffaloes.

i.1 heck dial ilk1 lecipicni of ilk1 cmhi v n is ;iiilk1 sank1 MatJi' ol ilk1 reprodlicli\ e cvclc asihcdonoi. and lhc\ aic used l r develop andcheck wavs D! nva i i i i ; j i cp ;oduc l i vcpnihk'i i is in animals usine hoi IIIDIK-S andoilier dr i l ls .

A l l lltese applications arc iiii|»>rl;iiilin iIK- "hiyh lech" animal hreedimjprogrammes currcnllv used in ihc indusiriali/cd world. Inn hormoik1 k lA'salso are ver\ imporlanl in devt lopingcouiilrics. I lere. their main use is in research ;;> monilor the ivporudeli\e ellieiene\ ol aniniaK and hi idenlil\ andeliminale animal liiishamlr\ practiceswhich are re.ponsihle tor Ihe poor hreed-in;_! pei loniumee ol animals olien ohseiA edin these eounliies.

I'or example , in someeounines. allow MIL; ihe call instickle its molliei slmis oi l iheac ln i l \ ol llie molheis o\anesloi lon;j pel lodsol l imeal lc i shehas caKed. Ihereloic. she can-nol lieconie pre;jnanl auam loim a n \ m o n l h s and canno lproduce anoiher call or haveanolhei laclal ion lo producemilk. I l . \ has iieen used lo e\aininc llus phenomenon and lode\elop call suck 11n;j regimesw h k h u i l l allow ihe cow \o\ anes io resume acl i \ i l \i | inckl\ .ilier c.ih iii ' j while al

:1111v~ nol , id\eisel\ al lecli i i ' j lllellie same I

heallh ol ihe call.

In Ihe sank1 vein. Kl A can he used lodevelop Iccdin;.' siialejjies whk l i allowannuals 10 breed more cllcclivclv in areaswhere ihe amount or qiialilv ol ihe Icedavailable is low. ami even 1<; idenlilvanimal breeds and l\pes which reproduceheller than olliers in harsh env lioninenls.I here are main wavs. iherelore. in whichradioisoiopes. in this case in Ihe lorni olKIA. are applieil lo the improvement olanimal breeding and hushandrv melhoilsilk1 world over.

l ina l lv . there is ihe widespread use

ol radiation and radioisotopes in animal

heallh. H\ eliminalin;j the disease causing

13

potcniial of sonic parasites, ionising radia-lion Iron) cobalt oOorX-iay sources is usedlo produce vaccines itirotiizli ilie aiienua-lion technique, which is boili sale aiul cosielfcclive. In liiirope. Ibi example.millionsol closes ol a commercial v accine based onirradiated Itingvvorm organisms are sold loproiec! young calves and lambs against adebilitating disease called parasiticbroncliiiis. which is caused by the presenceof worms in ilie lungs. In the UnitedKingdom alone, this vaccine saves live-stock producers over I'S S10 million peryear by Mopping the parasites fromdeveloping in the lungs and thereinprotecting animals against the weight lossor death which this infection normal!}brings about.

The other major area in the animalhealth field where the use ol radio-isotopeshas a major impact is in the developmentof serological tests to diagnose diseases. Itis extremely important to be able to diag-nose disease properly to determine withwhich drug or vaccine the animal shouldbe treated. This in turn improves thecosi-cifecliveness ol"programmes aimed at dis-ease control or eradication. To obtain thehigh specificity, and in some cases thehigh sensitivity needed lo differentiate onedisease from another, requires refinedbiochemical and immtmologica! methodslo produce the reagents which form thecomponents of the diagnostic test.

These methods rely heavily onradioisolopes lo label either the organismitself or antibodies which w ill attach to theorganism. In this way. the part ol the or-ganism or the particular antibodies neededfor diagnostic purposes can be indentifiedand purified.

Having identified and purified thesematerials, the presence of the disease-causingorganism in the animak's blood then canbe delected by adding blood serum to alube which has been coated with one ofthese materials. An immunoassav testsimilar lo that described earlier for themeasurement of hormones is then con-ducted, either using a radioisoiope (RIA)lest, or alternatively an en/vme ([{[.ISA)lesi to measure ihe binding ol the diseaseage'.t lo the antibody and hence diagnosing jthe disease.

The successes achieved In nuclearlechnit|ues in animal production, someworked oul and applied In Ihe 1AKA. aremain:

In Asia, an improvement in iheproduction of buffaloes w as made pos-sible by adding a lew kilos of cheapwasie material lo iheir iced. Thisresulted in nearly ft times less grassbeing needed to produce I tonne ofbody weighl gain per animal.

14

Ill Afr ica, nuclear methods are help-ing to l ight I M I I devastating dis-eases— r inderpes t ani l t r vpano -sontiasis—thereby increasing foodproduclion aiul incomes for smallfarmers.

In South America, isotopic methodshelped to preserve the alpaca andvicuna populations in the Amies,which helped lo improve ihc economyand wellbeing of low income farmersin the Highlands.

Insect control

Insects compete with man for food andfibre and are a threat to animal and

human health. In controlling insects withchemicals, we have sometimes createdproblems of environmental pollution andtoxic residues in our food. Also, maininsects have developed resistance to in-secticides, often resulting in more insec-ticide being used. Therefore, new ap-proaches to insect control are needed.

One way of control l ing or eradi-cating insects without the use of chemicalsis the sterile insect technique (SIT). In thisapproach to insect control, insects areproduced in large rearing plants, sexuallysteri l ized using gamma radiation, andreleased into the native population. Whenthe sterile insects mate with the wi ld in-sects, no offspring are produced. This ap-proach is not only environmentally sound,frequently it is the only practical means ofinsect eradication.

Sometimes the native population otthe target insect is H I M reduced by cu l -tural , b io log ica l , or at l ractai i l /chemicalmethods be fo re s ter i le insects arereleased. Then, when sterile insectsare released, the ratio ot sterile to na-tive insects is high and the probabi l i tyof a native insect mating wi th anothernative insect is low . II the ratio is highenough in an isolated si tuat ion, the in-sect w i l l be eradicated from that area.SIT is most ef fect ive when the sterileinsects can be produced in large num-bers, and the native populat ion is lowand isolated f rom other infestations.

It is an ideal way of eradicating newinfestations of insects before they spreadover large areas, but also it is effective inarea-wide control of established popula-tions. Further, pest-free /ones of agricul-tural production can be maintained throughthe use of the SIT.

15

Insect pests and the SIT

insect Previous use Current use

Screwworm

Mediterraneanfruit fly

Melon flyOriental fruit flyOnion fly

Mexican fruit fly

Cherry fruit flyOther fruit fliesPink BollwormCodling MothGypsy MothTsetse flies(4 species)Boll WeevilSheep Blow flyMosquitosStable flyTobacco hornworm

Curasao, USA. Mexico.Puerto P.ico. US VirginIslandsItaly(e). Peru(e). Mexico,USA (accidental intro-ductions)Japan(e)Ro!a, Hawaii (e)Netherland.s(e)

USA/Mexico(e)

Switzerland(e)

USA(e)Canada(e), USA(e)USA(e)Tanzania(e), Nigeria(e),Burkina Faso(e)USA(e)Australia(e)El Salvador(e)St.Croix, USA(e)St Croix, USA(e)

GuatemalaBelizeLibyaGuatemalaUSA (accidentalintroductions)Japan

Netherlands(control)USA/Mexico(quarantine)

Several countries(e)USA (quarantine)Canada (control)USANigeria

NOTE: The chart shows insect pests for which the SIT or a related genetic control method is being used, has been used,or is being developed. The objective is eradication unless otherwise noted. An (e) indicates an experimental pilot lest.

16

The New World Screwworm

SIT must be muicrlakcn on an area-w iih.1 basis lor an effective programme.Area-wide control of kev insects withoutheav v use DI' insecticides is often tIIL* mosteconomical!} anil ecologicalh sound ap-proach lo pest management. Ibis usual Ivinvolves an integration ol several methodsof insect control of which the SIT is oftena component.

The Joint FAO/IAHA Div ision is theinternational leader in the developmentand application ol the SI II or insect controland eradication.

New World Screwworm

The first successful eradication ol aninsect using the SIT was the screw worm, adevastating pest of domestic animals andwild life, on the island of Curacao in I°O4.I.;ttcr the screw worm w as eradicated fromthe USA anil then Mexico. Texas ranchers

alone estimate that I ho programme hassaved them I S SKID million annuallv . Inl'ASl>. ihe \ e u World Screw«unii wasreported in North Africa. This is the firstreporl cl lliis insocl becoming esiablishoiloutside the Western Hemisphere. The SITis ilie logical technolog) now being ap-plied lo eradicate this new introduction.

Fruit flies

Much ol the I'ruil proiluced througb-oui Ihe world is subject to fruit Ik infesta-tion, l-'ruil flies not onl\ damage the fruil.bin present countries inlesied with certainfruit flies from exporting their I'ruii locountries which ilo not have these flies.The Mediterranean fruit fl\ imedflvi hasbeen eradicated from Mexico and IheMelon I"K from most of Okinuw a using theSIT. In addition, several fruil fh introduc-tions have been eradicated from the L'SAusing the SIT. The Joint FAO/IAHADivision is conducting research to reducethe cost of sterile niedlly production. Also,a genetic sex ing strain has been developedso thai only male Hies are released. Thisincreases the efficacy of the SIT andavoids "stinging'"damage lo fruit by sterilefemales.

Tsetse fly

Tsetse Hies transmit a disease caus-ing nagana in cattle and sleeping sickness

17

in man. These insects have preventedsettlement and development of largeareas of Africa. One species of tsetseHies has been eradicated from parts ofNigeria and three species from parts ofBurkina Faso using the SIT. The JointFAO/IAFA Division has developednew tsetse fly rearing technologywhich makes mass-production of theflies in African countries practical foruse in SIT.

F-1 sterility

Certain groups of insects, such asmoths, are seriously damaged by steriliz-ing dosages of irradiation. Scientists havelearned thai some of these insects can beirradiated at lower closes which will notcompletely sterilize (he insect, but theirprogeny will be sterile. This inherited or

F-1 sterility is an effective way of control-ling some insects. Infestations of thegypsy moth have been eradicated inseveral isolated locations in the USA usingthis technique.

Other technology

Isotopes are commonly used to studyinsect movement, feeding, behaviour, andmetabolism. They are also standard toolsin biotechnology, including molecularbiology.

Standard insect genetics have beenused to study the compatibility of variousinsect strains and the hy-bridi/ation ofrelated species. In the future, geneticengineering will be used to developstrains of insects designed specificallyfor the SIT.

Food preservation

One of the first priorities in the worldis to have enough healthy food for

everybody. Great trouble is being taken tofertilize the land, develop suitable mutantsof basic crop plants, provide a suitableinfrastructure adapted to the country and,generally, create the right circumstancesfor a good harvest. After that we have todo more to make sure that the preciously

18

grown food is preserved and protectedagainst contamination and pests, an espe-cially important priority for the developingworld.

For thousands of years this problemhas been with us and preservation methodshave evolved from the earliest days of sun-drying to salting, smoking, canning, freezing,

Examples of worldwide approved uses ofirradiated foods and commodities

tryArgentina

Bangladesh

Belgium

BrazilCanada

Chile

China

CubaDenmark

FinlandFrance

HungaryIndia

IndonesiaIsraelJapan

Korea, Rep. ofNetherlands

NorwayPakistan

South Africa

SpainSyria

ThailandUSSR

USAYugoslavia

ProductSpices, spinach, cocoa powderPotatoes, onions, dried fish, pulses, frozenseafood, frog legs

• Spices, dehydrated vegetables, deep-frozenfoods, including seafoodSpices, dehydrated vegetablesSpices, potatoes, onionsSpices, dehydrated vegetables, onions.potatoes, chickenPotatoes, garlic, apples, spices, onions.Chinese sausage, Chinese winePotatoes, onions, cocoa beansSpicesSpices

• Spices, vegetable seasonings, poultry (frozendeboned chicken).Spices, onions, wine corkSpices, onions, potatoes

• Spices, (uber and root crops• Spices, potatoes, onions, grains

PotatoesGarlic powder, potatoes, onions

• Spices, frozen products, poultry, dehydratedvegetables, rice, egg powder, packagingITlQtPTI H 1 CIllalCl lalb

• SpicesPotatoes, onions, garlic, spices

• Potatoes, onions, fruit, spices, meat, fish.chicken, processed products, vegetablesPotatoes, onionsPotatoes, onions, chicken, fruit, spices

• Onions, fermented pork sausages, potatoes• Potatoes, onions, cereals, fresh and dried

fruits and vegetables, meat and meat products,poultry, grainsSpices, poultry, fruit

• Spices, cereals, meat, poultry

19

healing, and the addition of chemicals.The latest addition lothis list is inadialion.the exposure of foods lo eareUilly conirol-led aiiKHiiils olioui/iiii! radiation.

Although a relatively new commer-cial process, food irradiation has heensludied more ihoroughly than any oilierfood technology. More than 40 years ofresearcli have shown conclusively thaiihere are no adverse elfecls Irom ihe con-sumption ol' irradiated food. In lacl. lormany foods, ihe preservation of food by

irradiation has proved lo be In far ihe bestmeihod.

All necessary rules and regulationsto irradiate certain foods have beenadopted by the relevant internationalauthorities, lull there is Mill some publicreluctance over the acceptance of suchfoods. This is surely only temporary, andin the future food inadialion will certain-ly develop to be one of the great benefitslor mankind, and food preservation byirradiation will be of greaiesi importance

General applications of food irradiation

Purpose Absorbed dose (kOy) Products

; Low dose (up to 1 kGy)Inhibition of sprouting 0.05-0.15Insect disintegration and parasite 0.15-0.50disinfection

I Delay of maturation 0.50-1.0

Medium dose (1-10 kGy)Extension of shelf life 1.50-3.0Elimination of spoilage and 2.0-7.0pathogenic microorganismsImprovement of technological 2.0-7.0properties of food

High dose (10-50kGy)Decontamination of food addi- 0-50tives and ingredientsCommercial sterilization (in com- 30-50bination with mild heat)

Potatoes, onions, garlic, gingerrootCereals and pulses, fresh and driedfruit, dried fish and meat, fresh porkFresh fruits and vegetables

Fresh fish, strawberries, etc.Fresh and frozen seafood,poultry and meatGrapes (increased juice yield),dehyd-rated vegetables (reducedcooking time)

Spices, enzyme preparations,natural gum, etc.Meat, poultry, seafood, preparedfood, hospital diet

20

Fruits such as mangoes are preservedthrough food irradiation.

lo food products grown in developingcountries.

What ;ne ihe benefits of using ir-radiation'.' It can kill viable organisms andspecific, non-spore forming, pathogenicmicro-organisms such as salmonella, or itcan interfere with physiological processes,for instance it can be used for sprout inhibi-tion of potatoes or for extending the shelf-life of fresh fruit. In short, irradiation offood is an alternative, and in some casesthe only method to:

• eliminate many health risks in food:

enhance the quality of fresh produce:

• improve the economy of food produc-tion and distribution:

• reduce losses during storage ortransportation: and

• disinlesi stored products such as grain,beans, dried fruit, and dried fish.

Hconomicallv. one of the most im-portant applications results in the exten-sion of shelf-life, which is of utmost valueto countries with warm climates like somain of the developing eounlries. Thesame is true for the reduction of lossesthrough storage which are verv heavy insome areas. One can hardly believe it. butsome countries report 40-.SO percent post-harvest losses through infestation of staplefoods like grains and yams. Most storedstaple foods therefore are fumigated bychemicals when not irradiated.

At an international conference heldin Geneva in December IV><SN on the "'Ac-ceptance. Control of and Trade in Ir-radiated Food" a document was adoptedoutlining the benefits of food irradiationand recommending harmonization of na-tional procedures to facilitate international(nide in such producis.

Therefore, at last, all practicalobstacles seem lo have been removedwhich could hinder the fast develop-ment of this most useful application ofradiation to mankind in the very nearfuture.

21

Human healthapplications

Applications of radiation and radionuclidesfor human health followed rapidly in the

wake of the discovery of Ronlgen or X-rays.Techniques which permitted the production ofspecific radionuclides in useful quantities weredeveloped. Today, hardly a single major hospitalexists in an industrialized country which does nothave a department of radiology and a departmentof nuclear medicine, or which does not use an ex-

tensive array of laboratory radiochemical methods for the diagnosis and in-vestigation of a wide variety of diseases.

Nuclear medicineIn nuclear medicine, a radionuclide—in a carefully chosen chemical

form—is administered to the patient to trace a specific physiologicalphenomenon by means of a special detector, often a gamma camera, placed

22

Pakistan Atomic Rnprov rnmmi«inn

outside the body. The importance ofnuclear medicine, which is now arecognized medical speciality by iiself.may be seen from lhe fact thai one out olevery three patients unending a majorhospital in an industriali/ed countrybenefits from some type of nuclearmedicine procedure. Such proceduresmay. like an X-ray, provide us wilh apicture of some particular body organ or

part of it. The essential difference is that innuclear medicine the picture obtainedprovides a measure of the activity of somespecific physiological or biochemical(unction in the body.

Most nuclear procedures are of adiagnostic nature. Jn some instances, how-ever, radionuclides administered lo thepalieni are valuable therapeutic tools.

Radiopharmaceuticals

In order lo be able to trace a specificbiological process in lhe body, or inves-

tigate the functioning of a body organ, il isnecessary to make a careful choice of boththe ladionuclide and the chemical form inwhich il is administered to the patient.Such radionuclide preparations are calledradiopharmaceulicals. Today, some 100-300 radiopharmaceuticals are in routineuse for diagnosis, most of which are com-mercially available. The majorilyoflhe.secompounds are organic in nature.

To minimize the already small radia-tion dose to the palieni through the use ofdiagnostic radiopharmaceuticals. moreand more short-lived, or very short-livedradioisotopes are being used. These shorl-lived radioisotopes decay lo stable ele-ments within minutes or hours.

Radiophannaceuticals of short-livedisotopes have to be produced ;>! the hospi-tal where they are to be used. This is oftendone by "milkin«""ihedesired isoiope froma longer-lived radioactive parent. This is arelatively simple procedure, bul il oftennnis! be followed by some rapid chemicalprocedures to convert il inio the requisiteradiopharmaceulical. This technique isused routinely in hospitals for diagnosticinvestigations of the functioning of theliver, brain, lung, heart or kidney. Short-lived radionuclides such as indium-1 II.gallium-67.gallium-6S.ihallium-201.andthe most commonly used technelium-Wm.find wide applications.

New applicalions and radiophar-maceulicals are being developed to extendI he range of procedures available to doc-

24

lot's. I low e\ or. H a lwavs nuisi ho

remembered lhal a m in viva nuclear

medicine procedure i nvokes a small

radiation dose lo (he pa l i cn i . This is

not the case when in \ i iro procedures

such as ladioimi.Hinoassax iRl \> or im-iminoradioiiieii'ic assas ( IROAi arecarried oui lor ihe deleclion and meas-urement of clicinrcal components inbods fluids.

Nuclear cardiology and other diagnostic methods

R adionuclides pla> an important rolein cardioloeical diagnosis. When a

cloilor ovainiiK's die pulso of a palionl. heis t i \ inj! lo tl;niiio ilk1 hlooil How . jlldiio ilk1

oondilion ollhc Mood \ csscl. ami iiklitvol-k o\aluak' ilk1 lotvo ollho pumping aclionol ilk1 Ik-atl. A L'iivulaliiii! radioaoli\clivkor. like a small sp\. can rela\ the samekind DI' inrormaiion Iroin uiihin. smh aswhal tolume il occiifjies filler di! til it HI as ahlood pool in ilk1 heari. anil how [his\olimk1 I'IKIMIU'S when ihe heart eonlraeis.Wnhthehelpol'neominiier.sin.li inl'iw'Mki-lion is obiained i|uanlilali\ el\ and sei|uen-lially in ivlalion lo lime. Such imelli^eneeforms the hearl of nuelear cardioloLiN, oneof the most useful applications of modernnuclear medicine.

When a patient sees a doctor becauseof heart trouble, the doctor has main op-tions depending on his suspicions. Oneratherelaborale way lodiaiinosc isio injeela ratlioiechnelium compound into iheblood stream, followed bv an anahlical

mciluul known as single plinion cniissioncompuieil ioinoj;ia|)h\ (Sl'liCTi. A rolai-inji ^iiniiiKj laniera measures the radioac-l i \ it\ at slum iiHer\ als pro\ idins;. w iih thehelpofacoinpuier. aiecoiisirucledpicluie.which enables ihe plnsician to delerininehow much ol ihe heart muscle is depri\edof bloinl.

If ilie blood flow lo ihe hearl. .is wellas ihe metabolism of ihe muscle, are lo beassessed. Ihen another new method can be\er> useful. The positrons emit'.ed fromsome radionuclidcs which have been in-corporated in orsianic conipountls aremeasured h\ positron emission lomoy-raph> (Pf i l l . Hie posiirons are producedwhen certain shorl-li\ed isotopes deca\and. Ihroiijih interaction, produce \ er\sirons; iianima ra\s (511 ke\ ) which j;ooff in almost e\actl\ opposite directions.These can be delected easily In a specialde\ ice usinii detectors placed on opposiiesides ol ihe patient. During (lie last lew\ears. a much smaller and more sensiii\e

25

Images of the heart.

detector has been developed which willmake this method even more uselul in iliefuture. As 11 result of such measurements,one can show the distribul ion of the tracers,or rather the compounds containing thesetracers, initialling how melabolicallv ac-tive these tissues are.

There are many other usable positronemitters, like rubidium-82. which are usedto measure the blood How to the heartmuscle. There are other techniques as well,some using non-radioactive compounds bymaking use of the known X-ray computed

tomographs method. More recently. e\enmagnetic resonance imaging methods arebeing applied lor certain diagnostic work.Ultrasound techniques also are being triedlor certain heart assessments.

These examples illustrate that withsophisticaled radiation-emitting methods,it is possible to make diagnoses whichwould have been impossible not so longago. Roughly 3 percent ol the population ofHurope. some ft million people, sutler fromcoronary artery disease. A routine proce-dure could involve mam of them in

26

tomograpic tests using a radiophar-niacculical.

Nuclear imaging is useil more andmore wideh. such as for brain diseasediagnosis. Cerehrovascular diseases occural roughk the same rale as cardiactroubles. In these cases, organicradioclkmicak arc labelled with fluorine,oxvgen. nitrogen or carbon radionudideslor imaging. Tumours n>;i\ be located u iibsimilar methods, using either simple

radiopharmavViiiicak or complex radio-nuciide lah. iled aiiiibodies.

This is onl\ a small selection olmedical diagnostic uses where radio-isotopes pla> an important role, f:\perts inthe medical field have estimated how thefuture w ill look lornuclearmedicine. Theirprediction is that within the next 10 vearsthe general u*-eol nuclear techniques in themedical profession must be tripled in orderto deal w ith all the cases projected.

In vitro diagnostic methods

A huge number of medical tests, tens oreven hundreds of millions, are made

annually for diagnostic purposes. Thesetests are becoming more sophisticateddaily so ilia! loday one can diagnose apatient better from outside than fromwithin. These are called radioimmunoas-say tests. F-'or these, a patient does not1,'omc into contact with radioactivity as allthe tests are carried out in blood taken fromthe patient.

These methods have been so refinedthat it is now possible lo detect and followup certain diseases through extremely sen-sitive determinations (10-1(10 millionlimes more sensitive than with oldermethods) and the measurements obtained

are specific U> one substance onlv. In thiswav. hormones, vitamins. en/\mes. andmain drugs can be determined in blood orbiological fluids.

The IA HA is helping developingcountries to introduce these techniqueswhich have so main important uses, suchas delecting and measuring iodinedeficiency, iiinriiional disorders, andmicrobiolouical infections. Co-ordinatedresearch is helping de\ eloping countries toidentity several communicable diseases.The significance of these methods formedical diagnosis at present, and perhapseven more in the near future, cannot beoverestimated.

27

Radionuclides in the treatment of disease

Therapeutic nuclear medicine

There are relatively lew situations inwhich the administration of a radio-

pbarmaceutieal to the patient can be usedlor treatment ol disease. The oldest andbest known ol' these applications is thetreatment of overactliviiv of the thyroidgland and of some types of thyroid cancer.by giving the patient a carefully calculatedamount of iodine-131. to drink. Other ex-amples are the use of stronlium-K9 to pal-liate pain provoked by bone melastases ofprostatic. mammary and possibly othercarcinomas: or the treatment of phaeo-ehromocytoniu and other tumours of thecromoffin ;issue with iodine-131 labelledmelaiodo-ben/yl-guanidine.

Much hope for the future lies in thedevelopment of tumour-specific an-tibodies which could be used to targetradionuclides to tumours and therebydestroy them.

Teletherapy

Teletherapy is radiation treatmentwhere the radiation source is not in directcontact with the tumour to be treated. Theradiation used for the treatment can be ofdifferent types and energies and originate

from different sources, (iamma-cmiiiingtad ioaclive sources such as cobalt-60 ol tenare used, because the are convenient,need virtually no maintenance, and are al-most ideal gamma emitters. Many of thesesources are in use for cancer treatment.Telelherapy also can be administeredthrough other

Brachytherapy

Brachy therapy is a treatment wherethe radiation source is in direct contactwith the tumour. This method is usedwidely lor a number of special medicaleases.

As cancer of the cervi\ is quite acommon disease in many developingcountries, hrachlherapv has become themethod ol choice for treatment be-cause many patients can be treated rela-tively cheaply ;md effectively. One ofthe firs I big projects o f this kind in adeveloping country was organized inEgypt with the co-operation of theWorld Health Organization (WHO)and the IAEA. More than 10(1 traineesfrom various African countries learnedthis technique and introduced brachy-therapy to the hospitals in their homecountries.

28

A treatment called brachytherapy is used to treatcervical cancer.

This method, however, isonly applicable when thetumour has noi spread morethan a few centimetres. For-tunately, this is the case withman} patients. Should thetumour he larger however, themore costly leletherapy mustbe applied.

The usefulness of brachy-therapv for cancer treatmentcan he assessed when one real-izes that roughly one quarterof all cancer cases in Nigeria aresuitable for such treatment.With a relatively inexpensiveand uncomplicated applicationof radiobrachytherapy. onecan not only treat but. in espe-cially earh cases, also curemany patients.

Dosimetry

While dosimeliv is not an isotope ap-plication, accurate dosage ol radia-

tion is of the utmost importance for allradiation applications; for therapeutic ap-plications it can be a matter of life anddeath. lor this reason. src;,i efforts have

been made to ensure that radiation dosagesgiven to patients are as near as possible tothose prescribed.

The World Health Organization(WHO) and the IAHA. together with manv

29

IAEA/WHO TL dosimetry servicefor radiotherapy centres

(1969-1987)

NO O> PAHTlOPANIS t&bIOIAI NO Of RE SUITS '984NO O/ HFSUlTS WIlHIN 307. "Hh

•»•——I ^

national standard laboratories and with theInternational Bureau of Weight andMeasures, have been very active and suc-cessful during the last 20 years in ascer-taining that patients suffering from cancerdo gel the riglit radiation treatment whenusing the normal cobalt-60 therapy unit.For this purpose. 63 Secondary StandardDosimetry Laboratories have been estab-lished ol" which more than half are indeveloping countries covering some 700radiotherapy centres. As accuratedosimetry is a prerequisite in radiotherapy,all laboratories resonsible tor dosimetryhave to make frequent intercomparisonswith one of the Primary StandardDosimetry Laboratories. Radiotherapy hasbecome so important as the number of

cancer cases increasesin the world: it is es-timated that in somecoutnries. 2()-25cA of thepopulation will contractthis disease.

In the industrial-ized countries, roughlyhalf the cancer patientsare treated with radia-tion. Through great ef-forts primarily of theIAEA and WHO. im-portant results havebeen achieved. For70'/; of all hospitals par-

ticipating in a recent assessment, the meandeviations of their radiation dosage meas-urements was reduced to +5'/i: while theother centres are improving their measure-ments.

Much higher doses of radiation areused for some industrial applications, suchas sterilization of medical products andvulcanization of rubber, and food preser-vation. Newly developed techniques arebeing used for the assurance of theprescribed dose. This IAEA service alsois carried out through the secondary stand-ard dosimetry laboratories.

Additionally, both of these serviceshave a broad programme which includes

30

the calibration of all instruments in thelaboratories of llie participants, be il for

radiation protection, or high dose meas-urements.

Radiation biology

Nutrition

Medical products, such as surgicaldressings, sutures, catheters, and

syringes, usual!} are sterilized b\ themanufacturer. Many of these products, in-corporating heat-sensitive materials suchas plastic bases, cannot be subjected tosterilization by steam or dry heat.Sterilization byelhylene oxide gas or otherchemicals may introduce undesirableresidues which are hazardous lo health.

For such products, .sterilization b\ gammarays from cobalt-60 has proven to be high-ly effective and low in cost.

Biological tissue graft implants, suchas bone, nerve, fascia, dura, chorion am-nion dressings for burns, halso have beensuccessfully sterilized by gamma radiationand therefore have found more use in clini-cal practice in many developing countries.

Nuclear techniques during the last decadefound a number of important new ap-

plications in human nutrition research.Topics of current interest include adaption inenergy expenditure: a question relevant todeveloping regions of whether Indians canadapt metabolically. or otherwise, to lowlevels of energy intake. Another currenttopic is optimal diet therapy using localfoodstuffs for the treatment of wasting dis-ease in children (often induced by chronicdiarrhoea), and infectious diseases such asviral hepatitis. Stable isotope tracers of

hydrogen, carbon, nitrogen and oxygenprovide unique ways lo study theseproblems, and at the same time, are com-pletely safe to the person being studiedbecause they are non radioactive.

Nuclear analytical techniques alsohave been used to provitle information ondietary intakes of different elements throughthe normal human diet in various countriesof the world. These studies are providingimportant new data useful for settingdietary guidelines.

31

Industry

Many beneficial applications of radiation andradioisolopes in induslry are well estab-

lished in advanced countries. Their use ofradioisotopes and radiation in modern industry isof great importance for process development andimprovement, measurement and automation, andquality control. The growth in this field of ap-plication of radioisolopes started very early andwas rapid.

Today, almost every branch of industry uses radioisolopcs andradiation in some form. The use of radioisolope thickness gauges is aprerequisite for the complete automation of high speed production linessuch as for steel-plate or paper. Tracer experiments give exact informa-tion on the condition of expensive processing equipment and increase itsusable life.

32

Radioisotopes as tracers

Tlie fact thai minute amounts ofradioactive substance can be

measured readily and precise]) makesradioisoiopes an important tool lor inves-tigations in which iransport of material isinvolved and exact information about spa-tial and temporal distribution of thematerial is required.

A wide range of different industriesuse tracer techniques including:

coal,oil, gas and petrochemical.

cement, glass, buildingmaterials.

ore processing,

pulp and paper,

iron and steel,

non-ferrous metals, and

automotive.

The main areas where radioisotopetracers may be used are:

Process investigations: resiliencelime, flow rate, velocity, modelling,parameter estimation:

Mixing: mixing lime, mixer op-timization, mixer performance:

Maintenance: leak detection, imes-tigation of malfunctions, materialtransport:

\\ ear and corrosion: engine uear.corrosion ol process equipment, lubrica-tion studies.

In the processing industries, one ofthe major applications of radio-isotopetracers is for residence time investigationsin which important parameters for plantoptimization, modelling, and automationare obtained.

Once optimum performance of theplant has been reached, tracer experimentsma\ be carried out to indicate deviationsfrom optimum conditions. Often thereasons for malfunction are found, like un-wanted by-pass streams, or obstruction ofvessels anil pipes which can cause changesin Clou-rate or the appearance of deadzones.

Often the necessity for a shut-downcan be tested and vital inlormalion forrepair work to he done can be obtainedprior to shut-down. Typical examples arereported from the petrochemical industryfor the optimization of fractionatingcolumns.

34

Mixing is ;i very iinporumi step insonic processes. It consumes lime ;mdenergy ;uul expensive equipment is neces-sary. Optimi/alioii of mixinti processes,therefore, is an important goal lliat can hereached by the application of tracers. l;orexample, the mixing process in a 12 000tonne mixing silo lor cement raw meal wasstudied and design improvements weremade following the tests.

An example of radioisotope tracerapplications reported from India showsthat, even with a modest infrastructure,investigations with a high benefit can heperformed. During pre-commissioningtrials of a 140 km long crude-oil pipeline,small leaks were delected.

Conventional hydrostatic picssuri/a-lion and visual inspection were consideredto be loo lime-consuming and costly. Theradiotraccr technique was eventuallychosen for leak detection and locating.The technique enabled five leaks to befound and the entire 140 km length wastested within six weeks. The economicbenefits included a saving of US S300 000in investigation costs and a saving of sixmonths project lime, which resulted in anextra production of 1.5 million tonnes atthe oil ivfinery. The equipment necessaryfor carry ing out the investigation was ob-tained verv readilv in the counlrv.

The study of wear on machine parts,which were labelled by radioisotopes. is animportant siage in the developmcni workof the automotive industry. The design ofa new motor necessitates hundreds ol wearlesis to be carried oul. These tests can bemade by using the radioisotope tracer tech-nique. The surface activation technique, inwhich only a thin layer of the part underinvestigation is activated by bombardmentwith ions from an accelerator guaranteesextremely high sensitivity and uses onlysmall amounts of radioactive material.

Impressive figures are available con-cerning savings in the automotive industrydue lo the use of radioisotope tracers forwear studies. Reports say that in thedevelopment of a new engine the costs fortesting a new cylinder liner amount loabout IIS S3nO 000 lor each liner whenusing conventional wear measuringmethods. By using radioisoiope tracertechniques, the costs are cut to US S4S S00.for a series of measurements on Id linermodifications, which are usually madeduring the development process, thesavings made bv applving radioisotopetechniques would be US S3 I 12 000.

Similarly, the savings can be calcu-lated for tests on bearing cups. For a seriesof tests oil 20 bearing-cup modifications,the costs amount to US S3 500 000. Whenapplying radio-isotope techniques, the

35

same results can be obtained lor onlvUS S3X0 000 resulting in a savings ofUS SI 120 000.

In addition lo savings, there are Iur-ther technical advantages of great impor-lance. When using radioiso-iopes. dieentire test can be run without dismantlingihc engine which allows more accurateresults lo be obtained. A very importantfactor in development is lime. The

resu l t s fro in the test ser ies usingradioisotopes are usimlK available within6 months; the coin eiilional tests mav takeup to .̂ \eais.

In jieneral. tracer techniques areused throughout indusirv lo ini|iro\e theeliieicncv ol the processes, to save lime,encrgv ami raw maierial. lo rcilucc dow n-lime of eijiiipment. and lo lacilitalede\elopment work.

Radioisotope instruments

The greatest impact olradio-isotopes inindustry has resulted from the use of

radioisoiope instruments. Due to the na-ture of the ioni/int: radialion emitted fromradio-isotopes, a lew unii|ue advantajiesare provided when usinu this techiiitjue:

Because radiation has the ability lopenetrate mailer, measurements can bemade without direct physical contactof the sensor with the material beingmeasured.

• On-line measurements on movingmaterial can be made: measurement isnon-destructive.

• The stabilily of the source is excellentand little maintenance is required.

• fixcellenl cost/bcnelil ratios can beachieved.

Radioisoiope instruments becameavailable for all kinds of measurementsjusi when the trend towards automation ininduslrv was strong. Radioisotope instru-ments can perform certain measurementssuch as mass per unil area which cannot bemade by other equipment. For oilier meas-urements, like level or distance, there arenow oilier compel int: methods available.

Radioisotope gauges for measuringmass per unit area (sometimes also called"thickness gauges"! are unequalled in theirperformance and are used in almost everykind of industry in which sheet maierial isproduced. In the paper industry, not only

36

I lie iiKiss per niiil area of the paper slieeli l se l l ' is measured b> r;icli i)isi>ii ipegauges, ilie production ol the fell, whichis used lo support ilie set \er\ wet pulpin [lie lirsi slaves ol paper production,relies heavily on Hie use of radioisi.-i.'pcgauges to guarantee its extreme unil'or-niilv. as well. The hitler is ol'viuil impor-tance lor I he paper machines operating athigh speed.

Similarly, the production of steelplate at the speed of modern roiling millscould not be done ^ ithoul accurate meas-urement ol thickness at every moment olthe production and automatic control ofthe rolling stands.

In (lie plastics iiiilusirv. radio-isotope gauges are used lo improve theuniformity of the product and hencesavings can be made in raw material andin energy needed for the production. Inaddition, better product qualil} reducescosts for rejects and customer com-plaints.

Microprocessor technology had agreat impact on the development ofradio sou>ne instruments. Lineariza-tion ol complex calibration curves,c o m p e t i t i o n for the decay of theradioisotope. and performance of im-portant calibration checks can be hand-led easily by the microprocessor. In this

wa\ . radioisotope instruments of modern

design added \e l another dimension of

rc l iahi l i lv and sophist ication to their

proven e\cellcncc.

IJensii\ gauges based on the ab

sorpiion ol gamma radiation are used

wherever the automatic determination

and control of the densiu o| l iquids,

solids, or slurries is important. 'I he oi l

industry relies hea\ i l \ on such insiru

menls. Other applications are in the ban

dling of slurries in mineral processing 01

even in the food industry. One ol the

earliest users of radioisotope instruments

was (he tdhacco indus tn . ul iere densii\

gauges make sure the rinht amount ol

tobacco is packed into each cigarette.

The coal uulusirv has beneli tedgreat ly th rough the app l i ca t ions >i|nuclear lechiiiques. Niicleoiuc gaugesand on-siream anai\ sers are now iv ju la rIs employed for monitoring and controlling the ash and moisiure content m coalanil coke.

Nuclear techniques make possiblethe on-line ileterminalions ol siilphur andnitrogen (the causes for acid raini in coal:both of these are imporlaut lor pollutioncontrol. Hundreds o! mil l ions ol tonnesof coal are anah /ed annualU b\ 1111-.method, a process which has becomeroutine in the coal industiA.

37

Radiation fimm radioisotopc sourcescan be used lo excite characteristic X-ra\ sin samples upon which the beam of radia-tion is directed. Detection and analysis ofthese X-rays yield information about thecomposition of the sample. This opens thefield o( industriul X-ray fluorescenceanalysis. The most f-vqueni applicalionsare in the ore processing and the metalcoating industries.

In ore processing, a sample streamof the slurry of ground ore is led to ameasuring head containing the radio-isolope source and the X-ray detector. Theexact composition of ihe slurry can bedetermined and the operation of the planlcontrolled to give optimum perfor-mance. Great savings can beachieved by better utilization of rawore. energy, and chemicals used forthe process. Although the cost ofsuch an instrument including instal-lation is of the order of US $200 ()()().il can be recovered usually withinone year of operation.

In metal coaling, such as gal-vanizing or tin-coating of steel plate,the exact amount of coating must beapplied. A surplus of material is ex-tremely expensive: undercoat ing*results in complaints and early cor-rosion. Through the use of n'dio-isotope gauges, coaling processes

can be controlled lo meet light limits andthus up lo 10'; of material (/inc. tin) canbe saved. At the same time, the reject ratedue to undercoated snip is reduced.Savings in Ibe order of US$200000 per yearare not unusual, resulting in a pay-hack ofiheinvestment for the gauge within (he samelime.

In the production of sheets and platescm lo a certain length, special sieps aretaken to measure (he exact length ofmaterial when il passes the gauge. Digitalcounting techniques are preferred for ihistype of measurement because the liming ofthe measurement can be made to lit exactlythe desired stretch of material. Results can

Nuclear techniques using a coal-scan are used todetermine amounts of environmental pollutants incoal.

38

be given lor each individual sheet or plateor an average value for 10. 20. or 100pieces can be computed.

Level measurements can be made byinstalling a source and a detector on oppositesides of a lank or silo. When filled, thematerial absorbs the radiation otherwisesensed by the detector. This technique ismost useful where circumstances such aspressure, heal, or when the presence of toxic,corrosive, or abrasive substances make ac-cess to the lank ami installation of conven-tional gauges difficult or impossible.

Level gauging using movable source -detector combinations is a useful tool for theinspection of process equipment such aschemical reactors. Checking catalyst lewisin chemical reactors or monitoring the opera-lion of large fractionating columns inrefineries are two applications widely used.Again, savings can amount to impressivefigures if one considers that down-time costsdue lo production losses of a distillationcolumn in a petroleum refinery can be in theorder of US$300 000 per day.

Yet another extremely useful ap-plication ofradioisotopes which can saveconsiderable costs and prevent severedamage is in quality control during theconstruction of pre-slressed concretebridges. The strength of these bridges isbased on brae in si cables which run

through encasing tubes in the bottom sec-tion of the bridge girder. If the bracingcables do nol lie in a straight line, consid-erable damage lo the building may resultwhen the necessary stress is applied to ihecables. Parts of the concrete slab may becaused lo lly oil due to the unexpectedforces, representing nol only a severeha/ard. but also necessitating a completereworking of the struclure.

A radioisotope source, which is in-serted inlo the encasing tubes and pulledthrough before the bracing cables arepulled in. is used to determine the exactposition ol the tubes. If any deviation fromtheir target position is observed, correctivemeasures may be taken before damage tothe building occurs. Such deviations canoriginate when the encasing tubes arcdetached from their fastenings by the forceof the concrete cast into the sheathing.

Neutron moisture gauges are suitedespecially well lor measuring moisture inbulk material such as sand. Their use inIhe production ol glass and concrete con-tinues to grow. Portable instruments areindispensable for checking thicknessesof bituminous material in the construc-tion of roads and dams. A gamma den-sity measurement completes theimportant information about the qualityof the construction. A novel, routine useof neutron sources is in ihe rapid delec-

39

lion of hidden explosiv ON. AH insiruiiienth;is been developed lhal can delect smallanu.unis of explosives bv measuringgamma ravs emiiied when neuirons arccaptured h\ nitrogen aloms which arepreseiu in anv explosive. The gauge isiniended lor ihe ronline inspection of lug-tiaiio al airports.

Nuclear techniques such as nuclearhore-hole logging and radiometrie in-siiuanahsis pla\ an increasingly iniporianirole in exploration lor oil. gas. and metal-liferous minerals.

Gamma radiography

Radiography using X- or gamma-iays is well established and is a rouiinelvused technique ol non-destructive qualil}control. It is applied lor checking welds,eastings, assembled machinery (such as jetengines), anil in ceramics.

Radioisolopes as a source ol radia-tion offer the advantage that thev do notrequire eleclrical power so that they can heused readily in the field. Different sourcesare available as well, ranging from low tohigh energy. The small si/e ol radio-isotope sources allows inspection of partsor machinery which could not be ex-amined bv X-rav tubes.

The most frequent application ofgamma radiographs is checking the weldsin pipelines. This is done most con-veniently bv pulling the source inside thecentre of the pipe and attaching the film toIhe outside ol Ihe weld. lor cheeking longpipelines, sophisticated, self-propelledcrawlers which travel in the pipe are used.These dev ices can be positioned exacllv althe desired position from the outside. Al acommand the exposure is made. Then theciauler is instructed to move on to thenexl weld. Praelicallv all new gas- oroil-pipeline s\ stems are checked w itli thistv pe of equipment.

The latest development is the use ofdirect imaging gamma-cameras which areable to obtain an X >>r gamma-rav imagedirectly w ithoul the use ol photographicfilm. Computers are used to build up. in-tegrate, and improve Ihe image h\ filteringmethods. This technique appears to bepromising. Advantages are thai the imageis available right al or shorllv after theexposure, nochemical processing is neces-sary, and the expense of photographic filmis saved.

Autoradiography

The radiation emitted by radioiso-topes which are present in a specimen can ;be used lo create a photographic image of jtheir distribution. This technique, which is

40

called auloradiography. is used widely inbiological research and metallurgical in-vestigations. I he leehnii|iie often is combilled with tracer investigations. Typicalexamples are ihe inv esi igal ion olsolidilicatioi /ones dining (lie casting olsleel. die observation of segregation olcertain alloying elenienls. and Ihe studyof die distribution ol lubricating films inhearings.

Aclne\eiiien|s in recenl years ha\ebeen towards beller resolution and loweramounts ol radioactive substancesbeing inv olved.

Neutron radiography

Neutron radiography is based on theattenuation of a neulron beam by inlcrac-tion wilh alonis. Differences in cross sec-lions and hence beam ailenualioii byelements are marked al the lower neutronenergies. Some elements such ashydrogen, cadmium, and boron, showstrong attenuation. Their presence, there-fore, can be detected easily lor thermalneutrons. For radiography, beams ofneutrons i>iay be extracted from nuclearreactors, radioisolope neutron sources, anilhigli-ouipul panicle accelerators.

The typical applications of neutronradiography are the testing of nuclear reac-tor fuel and Ihe detection of hvdroiienous

materials. This technique is used to detectflaws in gas turbine blades ami corrosionol aircrall components, to control thequality ol ceramics, and lodeiecl explosivecharges and the presence ol lubricationlilnis inside gear boxes or bearings.

Smoke detectors

Modern smoke delecting deviceswhich are installed in large numbers in fac-tories, shops, offices, hotels, and shoppingcentres, are based on radiation emitted froma small radioisolope source. The sourceproduces a constant current in a cell repre-senting an ion chamber. Smoke particlesentering the cell hv convection of ambient aircatch the electrons and reduce the ion cur-rent. This change niggers the smoke alarm.These devices are extremely sensitive andtheir reliability is as yel unmatched.Whereas alpha emitting sources are usedmost frequently .ihe use of noble gas kryptonX? has been reported, ll offers the advantagethai the harmless ga> disappears rapidly incase of damage to the device.

Light sources

For many years, luminous watchdiais were made using points with naturalalpha-emitters such as radium. This harm-ful natural radioisolope has been replacedcompletely by art i f ic ial ly produced

41

radioisoiopes (tritiumj which reduce' theradiation ha/ard almost to /ero.

Glass bulbs filled will] liiii'.ineseenipaint and tritium gas are used as lasting,fail-sale light sources Ibremergencv signsin aircraft, and in public buildings. Smallversions of ihese light bulbs are used toilluminate liquid crystal dispkiv s in digitalwatches.

Radiation in manufacturing

Radiation can induce certain desiredchemical reactions. It can. lor example, beused in the milking of plastics, or to graftplastic to other materials. Some polymerswhose cross-linkage is induced by radia-tion can be tailored to shrink when heated— a desirable property in some packagingapplications. The wood and printing in-dustries make extensive use of electron-beam radiation to cure surface coatings.

The rale of production of wire andcable insulated with radiation cross-linkedpolyvinylchloride is increasing steadily.Such insulation has better resistance toheat and chemical attack and increasedcut-through resistance, and is more com-pact. The products are used in theautomobile industry, telecommunications,the aerospace industry, and in homeelectrical appliances.

Other important products includeradiation cross-linked foamed poly-ethylene which is used lor thermal insula-tion, floor mats, crash padding, floatingjackets, and wood/plastic compositescured h\ gamma irradiation. These ha\ebeen used successfully for flooring inplaces such as department stores, airports,hotels, and churches where their excellentabrasion resistance, the beauty of thenatural grain, and low maintenance costsare important. This latter technique also isbeing used in the conservation of objectsmade of stone and wood of interest to ourcultural heritage.

The vulcani/alion of rubber sheet byradiation—instead of using sulphur in themanufacture of lyres—is being used com-mercially h\ several tyre companies.

A "'super-absorbent' materialmanufactured by radiation grafting techni-ques has come onto the market recently. Thematerial is capable of absorbing and holdinglarge amounts ol liquid. Products manufac-tured from it include disposable diapers,tampons, and air-freshner elements.

Radiation is beginning to be used todecompose septic or poisonous waste.Some cities irradiate human wasteproducts. Radiation replaces the otherwisenecessary addition of chemicals such aschlorine, a poison itself.

42

Kailiulmn process in i! has greatpotential in a new area of applicationknown as radiation immobili/alion olbioactivc materials such as drugs, en-zymes. ani i ; ' ins. and antibodies onpolymeric materials. Sucli immobi-lization assures belle;' siabiliiv and longershelf-life for the sensitive biologicalmolecules anil offers the possibility olproducing slow and sustained drugdelivery systems lor prolonged controlledtherapy of many diseases.

Electron beam processing

A recent development in radiationprocessing looks very promising to reducethe en\ ironmental and health impact of thelarge-scale combustion of fossil fuels.

The emission of SOj and NO\ intothe atmosphere from coal-and oil-firedboilers in power plants and industrial in-stallations has been recognized as one olthe main sources ol environmental pollu-tion. Such emissions have been significantcontributors to environmental problemssuch as "the greenhouse elTeel" and acidrain.

CYiivenlionaJ techniques usingequipment know as scrubbers efficientlyremoves SO2 from Hue gases. Althoughsuch techniques help to address the prob-lem, some removal processes result in

by products vv ilh no commercial value andresult in byproducts that pose additionalproblems of waste disposal. No reliablechemical methods have yet beende\eloped for siniullaneious removal olboth SOj and N(K gases in one single-stage process.

Klcetron Beam <HB) processing offlue gases has pros en its potential lor im-proving air quality anil eliminating acidrain problems hy effectively removingSO2 and N().\ from Hue gases in a single-stage process and converting these toxiccomponents into a byproduct with com-mercial value as agricultural fertili/er toimprove soil conditions.

Commensurate with the greatlv in-creased w--: ol radiation technology in in-dustrial applications, the reliability ofradiation facilities using sources such asCobalt 60 and electron beam acceleratorshave improved grcallv in recent years.

The application of radiation anilisotopes in industry is an important com-ponent ol the I AHA programme. Throughtechnical co-operation projects, the Agen-cy provides developing Member Staleswild expert advice, equipment, and train-ing. Multinational regional projects onnuclear industrial applications have beenestablished in South Hast Asia and LatinAmerica.

43

Hydrology

The total amount of water on this earth is virtuallyconstant but its distribution is not. Wherever

people live, they must have a clean, continuous andample water supply as a fundamental for life. Theassessment of quality, supply, and renewal ofresources is a well known problem, but it is gainingin importance as populations grow and pollutionincreases.

Before the use of isotopes and the instrumentation developed for measuringaccurately both radioactive and stable nuclei, it was very difficult, sometimes im-possible, to solve many hydrological problems which are soessenlial for the plan-ning of agriculture, industry, and habitation.

Hydrology is a subject where isotopes may play a leading role in manyresearch activities as well as applications. Many problems are fundamental:therefore, isotope techniques are an important tool for the hydrologist. Realiz-ing this, the Agency conducts important work in this Held. There is hardly aMember State which has not benefited from these important nuclear applica-tions, often through Agency assistance.

44

45

The problem.s where isotopes play animportant role include:

(•round waterorigin,a ye.distribution,water quality,occurrence and rechargemechanism, andinterconnections betweengroundwater bodies (aquifers).

Surface waterdynamics of lakes and reser-voirs.leakage through dams,seepage to subways,river discharge measurements,suspended and bee) load sedi-ment transport,sedimentation rate, andother data OH lithology. porosity,and permeability of aquifers.

Methodsuse of artificial isotopes, anduseofenvironmenial isotopes.

Artificial isotopes are used primarilyto s o k e relatively local hydrologicalproblems like leakage from dams or delin-ing ground water protection /ones .They also are used to identify waterflow patterns in highly fractured rockslike karst where the flow of the groundwater is relatively fast.

In recent times, more environmentalisotopes are being used such as oxygen- IS.hydrogen-2 (deuterium) and hydrogen-/!(tritium) which are all part of ihe watermolecule. They are ideal tracers anil, sincethe\ are environmental isotopes, there is nodifficult} in public acceptance.

In main cases, siill more informa-tion can be ob ta ined by app ly ingsophis t ica ted mathematical models:some of these already are usefully ap-plied to obtain more information for theinterpretation of t racer t ransport inground water systems as well as thetransp. rl of solutes.

Applications

Isotopic methods are normally usedtogether with established conventional

hydrological ones: so. in most cases, theuse of isotopes provides an additional and

valuable tool for solving many hydrologi-cal problems. In recent years, in hundredsof difficult cases, isotopic methods haveprovided definite, satisfactory results.;

46

Here are some examples which demon-stratc that important decisions can belaken as a result of lJie.se measure-men is:

• By using isoiopic methods in arid orsemi-arid / ones , the aue ol' the

groundwater at planned industrialdevelopment locations can be deter-mined. In one case it was found to be20 000 years old. This indicated thatthe uroundwaler had no contact withnew resources and that the areawould run drv alter a short lime if this

Distillation units are used for ground water before enrichment for natural tritium.

47

groundwater were to be tapped.Kolopic measurements were essen-tial in avoiding a large and uselessinvestment.

Oilier problems in arid areas have in-cluded comparisons of transpirationand precipitation. In such instances, itis important to determine quickly ilrecharge is taking place and to establishthe recharge mechanism. In the groundwater of the Kalahari desert inBotswana, lor example, the tritium con-centration was found to he comparableto thai in ihe sparse precipitation of theregion. This confirmed that a fairlyquick recharge occurred and that thewater could be tapped and used.

A similar study was a co-operativeeffort between the Agency and ihe na-tional water organization of Mexico onrecharge mechanisms in a coastal areasouth of Veracruz. Here, the rainfall isabundant but it is matched byevapotranspiralion. It was importantlo find out whether a recharge by in-filtration of local precipitation oc-curred. This was confirmed by isotopemeasurements. Additionally, infiltra-tion losses from a river crossing thecoastal plain were estimated.

Water pollution or high salinity ismeasured by chemical means, but the

causes of the pollution ofien can beestablished b\ isotopic methods. Onecause can be intrusion ol sea water incoastal aquifers. With the help ofisotopic melhods. such sources of pol-lution were iounil in Mexico. Crete, andPortugal.

Only environmental isotopes can beemployed where big areas are involved.The huge Continental Interealairesandstone aquifer of the northern Saharahas been studied using isotopes whichdemonstrated the existence of leakagefrom the sandstone aquiler lo anotheraquifer. In the eastern part of thisaquifer in Tunisia, isotopes showed thatwater from this large aquifer leaksthrough a fault system. Hvdrologists areoften confronted with the problem ofwhether a fault is or is not a barrier toground water movement.

Dynamic sedimentological isotopemeasurements and erosion deter-mination gave important answers inSingapore, where there were siltationproblems in the harbour and thedanger ol erosion of newly recoveredland from the sea to be used for thenew Singapore airport. Using ar-tificial radioisolopes. the existingproblems could be solved, includingthe hazards of beach pollution, silta-ilion of harbour installations, and,

48

mmm

Countries with isotope hydrology activities inwhich the IAEA has participated

AfghanistanAlbaniaAlgeriaArgentinaAustraliaAustriaBangladesh

BoliviaBrazilBulgariaCameroonCanadaChileChinaColombiaCosta RicaCubaCyprusCSFRDominican RepublicEcuadorEl SalvadorEthopiaFianceGermanyGhanaGreece

GhanaGreeceGuatemalaHaitiHungaryIcelandJndiaIndonesiaIranIraqIsraelItalyJamaicaLibyan Arab JamahiriyaMalaysiaMaliMauritiusMexicoMongoliaMoroccoNamibiaNew ZealandNicaraguaNigerNigeriaPakistanParaguay

PeruPhilippinesPolandPortugalQatarRomaniaSaudi ArabiaSenegalSingaporeSpainSri LankaSudanSyrian Arab RepublicThailandTunisiaTurkeyUnion of Soviet Socialist

RepublicsUnited Arab EmiratesUnited KingdomUnited Republic el TanzaniaUnited States of AmericaUruguayVenezuelaViet NamYugoslaviaZaireZambia

49

Nuclear techniques are used to "date" ground water in the desert. (T.Akiti)

possible erosion which could have en-dangered the new airport.

Interactions between ground waterand aquifer matrix has been studiedsuccessfully using environmentaland artificial isotopes. A technicalco-operation project in the alluvialaquifer of the Sebaco valley inNicaragua brought solutions to manyproblems. The valley is surrounded

by mountains of volcanic rocks and iscrossed by two rivers. Environmentaland artificial isotopes were appliedand the following important data es-tablished: direction of flow inboreholes, recharge at the four edgesof the valley, the downward verticalflow of water in boreholes, the age ofthe ground water, and lastly, it wasestablished that no recharge occurred;by infiltration of local precipitation. ',

50

ll is obvious from these lew illustra-tions lhat isotopes, environmental and ar-tificial, can solve, or help to solve,important hydrological problems at littlecost. It is not surprising therefore, that (heAgency has had close contact with or es-tablished programmes in 85 countries, oneof the very successful types of assistanceprovided to boih developed and develop-ing countries.

Isotopes have proved very useful infeasibility studies for projects. One ex-ample is a feasability study to increase thestorage capacity of a lake by constructinga dam in northern Ecuador. The first stepwas to establish the present seepage fromthe lake and evaluate the possible in-creased seepage owing to the much in-creased water pressure.

The following information was ob-tained from the measurements:

• The presence of a clay layer was estab-lished;

• The presence of a sandy layer wasestablished;

The lake does not contribute to arecharge of the sandy layer;

The sandy aquifer shows a significantcontribution of water coining from aprecipitation period from l°-85 back to1970;

A vertical How was established whichcould be attributed to discharge ofground water; and

Different penneabilities and therefore,different water velocities were estab-lished.

The conclusion was that an impor-tant seepage must be expected if the damwere to be built at this place. Anothersite would be a belter choice for the con-struction of;; dam. but even then it uasthought lhat cement injections ma\ benecessary.

An advantage of nuclear methods isthat they can provide within a short time adefinite answer and the measurements arerelatively inexpensive.

51

Geology,geochemistry,geophysics,and dating

N uclear methods are playing an important andsometimes decisive role in geology. They are

used, for example, to determine the physics andchemistry of soil. The methods used for explora-tion purposes are:

• gamma-ray speelromelry.• gamma-ray scattering.

neutron emissionpulsed neutrons, and

• natural radon.

52

53

I he\ arc being used in sur\e\s ollock. soil, biologv and water.

Nahiral radioactive minerals play animporiani pan in geology. I here are 1°different elements which haw 45 natural!}occurring radioactive isotopes, all ofwhich arc in minerals anil can he used forassessmcnl of ihcir age and properties.From these I'.* elements, the three mostIreijuenlly represenleil in minerals are:

• I'raniurn:

• Thorium: and

• Potassium.

In prospecting for mam minerals andoil. nuclear methods are routine proce-dures. The methods have been vastly im-proved during the last 10 years or so bybetlerand more sophisticated instrumenta-tion and easier evaluation through com-puterized data processing methods.

In well logging in a borehole, wherecharacteristics of rock formations are auto-matically recorded by traversing a meas-urement device, very often a nuclear one.one can measure density, porosity, andchemical elements and establish the lithol-ogy. Hydrogen-containing strata, whenwater or oil are present, can be identifiedby the strong absorption of neutrons or. in

the case where sea \\ aler has penetrated thestrata, the chlorine present can hemeasured through a spontaneouslyemitted, penetrating secondary gamma-ray. Lasers, even thin ones, ol sandstone,dolomite, or limestone can be located andmeasured. The mam nuclear applicationsin the exploration of mines are mentionedin the chapter on inclusirv.

Isotope dating methods constitute afield which is constantly gaining impor-tance as measuring methods are refined.Many people do not reali/e that nature hasnot only given us many radioactive sub-stances, but that more are constantly beingcreated by cosmic radiation. One is carb-on-14 which is made by the interaction ofcosmic radiation with the nitrogen con-tained in air. Living plants take up theradioactive carbon in the form of carbondioxide. When the plant dies, the uptakeceases and the carbon-14 in the dead plantdecays with a half-life of about 5 730 years.Therefore, the longer the plant is dead, themore carbon-14 has decayed and fromthis, the time elapsed since the death ofthe plant can he calculated. \

This method lends itself to age deter-minations of carbon containing objects |which are between 1000 and 40 000 years jold. ami is widely used for dating soils,shells, marine sediments, trees, ar-chaeological sites, bones, and textiles.

54

Practical demonstration of tracer injection into a well to determine aquifer characteristics.

This niL'tlnnl w as also used, lor instance, todetermine the age of the most discussedTurin slirnud.

In recent years, a renaissance ofmethods using en\ ironmental isotopes ingeochemistry as a dating tool has beenoberved. An example is the developnienlof accelerator mass speclromelry. a novelanalytical technique ill low iin; the deled ionof low concentrations of environmentalradioisotopes in very small samples.

The enormous quantity ol isotopicdata of various types accumulatedu oi'ltlw ide demonstrates ihal em iromnen-lal isotopes are a powerful tool to inves-tigate climate, as well. C'limatologicalinvestigations making use of isotopetechniques are being conducted in manylaboratories. In many cases, the aim isthe I nor i". ugh understanding anddetailed prediction of climatic changeswhich should become evident in the nextcenturv.

55

Environment

Environmental pollution is today a worldproblem which needs immediate counterac-

tion. Before beginning any action to reduce pol-lution, one has to be sure of three facts:

• the exact amounts and places of occur-rence of pollutants:

• the causes of pollution (they may besecondary reactions): and

• the proper remedy to avoid the pollutionwithout creating other undesirable ef-fects.

Isotopes, radioactive and non-radioactive ones, are ideally suited toanswer the first two questions, in most cases. The fact that isotopes can bedelected in very small amounts and. perhaps more importantly, that theirpath can be traced, make them an ideal tool for tracing pollutants, be it in air.sea. or soil.

56

57

Methods for their detection have beenimproved. Noii-r;idioactive isotopes canbe measured accurately by nuclearmethods like activation analyses or X-rayfluorescence, the latter being ideal Tor usein the field.

Air

The greatest world problem whichcalls for immediate drastic action is globalwarming (greenhouse effect). Thisdangerous continuous warming of our at-mosphere is due to a great extent lo thecarbon dioxide released from burning coaland organic matter like petrol, wood,waste, etc. Establishing the amountsand ways of assimilation of this gas byplants and the sea is a major problem:ami in this area, isotopic methods canplay an important role. In helping tosolve other pollution problems, such assulphur dioxide in the atmosphere ord is t r ibut ion of gaseous emissions,isotopes play a significant part.

Not only in measuring orestablishingthe path of pollutants are isotopes useful,nuclear methods such as electron beamradiation also can be employed successful-ly to remove gaseous pollutants, includingobnoxious gases such as sulphur dioxide ornitrogen oxide, emitted from coal-firedpower stations.

An ingenious and simple method toassess the releases of carbon dioxide in anindustrial area into the local atmospherehas been developed. The normal air con-tains some radioactive carbon-14 due tocosmic radiation, which as carbon dioxide,finds its way into a plant or leaf grow ing inthai area. Carbon dioxide deri\ing fromcoal and oil combustion contains practical-ly no radioactivity. A plant growing in anindustrial area would assimilate the mix-ture of the two carbon dioxides from dif-ferent origins and the more man-made(non-radioactive) carbon dioxide ispresent, the smaller will be the radioac-tivity measured in a leaf of such a plant. Inthis way. an average v;.lue for the totalcarbon dioxide emission in this area can becomputed.

Water

To continue the above mentioned"global carbon dioxide" cycle, it is impor-tant to study carbon dioxide in the sea. Bytaking advantage of the different chemicalbehaviours of certain thorium and uraniumisotopes, it is possible lo measure the speedat which microscopic phyioplankton cellsare aggregated into larger particles and-subsequently sink out of the biologically!productive upper layers of the ocean. The]knowledge of such biologically-mediatedremoval rates in ocean waters is necessary

58

ID 1'ulk understand ihc global carbon aswell as the carbon dioxide cycles.

The multi-clement capabilities olnuclear techniques are particularly usel'iilin the stuiK ol air pollution, since thekit uo volume of data oblained can be usedIn patter recognition compuier prog ram -nies ID identify anil quaniils some ol thedifferent sources of pollution, whetherfrom intlusirial.soil-baseil. forest-burning,or o! marine or ig in.

An elegant nielhod 10 measure phvlo-pkmklon pollution ol'w ater reservoirs usescarbon-14 as a radioactive tracer. Asample from ibe reservoir is brought intocontact with carbon-14 labelled carbondioxide. The phvioplanklon in the watertake up llie radioactive carbon ilioxide Toruse in photosynthesis. The greater themeasured radioactivity, the greater thephvloplanklon pollution.

Soil

As the pollution of air and water isperhaps more visible, and iherelore wasnoticed earlier, soil pollution has nowbecome a big problem of the same sig-nificance as [he oilier sources of environ-

mental pollution. This problem has beenneglected lor a long lime although pol-lutants ha\e been appearing more andmore in the looil chain. Agriculture usesperhaps the greatest amounts ol chemi-cals which enter the soil either as ler-lili/ers or as pesticides.

Poisonous pesticides must be testedcarcfullx to ensure thai ihe\ decompose intoproducts which do not harm man or animal.An important application ol isotopes is toidentils • the deconipositon products and wherelhe\ iiune.

Another environmental agriculturalproblem is often the unused fertilizerw hiclulecomposes into ox illation productsof nitrogen and therein can become aserious problem.

Nuclear methods are ideal for assess-ing pollution accurately. In main cases,they can determine the exact source of thecontamination. There are mans dail\ oc-curring pollutions in soil, such as leakingpipelines containing, for instance humanexcrement, or petrol, or surface spillagesof transported chemicals, where isoiopicmethods pla\ an important part I seeliuluslrv I.

59

Basic scientificresearch

Isotopes can be built into chemical compounds,thereby giving them a label. In any reaction

one can follow the labelled compound and findout about a possible decomposi t ion or thewhereabouts of the decomposed products. This isof utmost importance for biological investiga-tions and may have very wide scientific applica-tions.

For example, any compound which lodgespreferentially in a tumor could be discovered il it contained a radioisotope.This technique has been tried for many years and great progress has beenmade in this promising field of research. Isotopes are also used in complexstudies concerning the functions of the brain.

In modern genetic development, radioisolopes have a function, as theyhad in the past, when isotope labelled atoms played a role in proving the

60

Watson-Crick model of UNA. ihe yenclicmaterial ihiii is I he carrier of genedcinformation. C'hemisiry—railioehemistryas well as radiation chemistry—ha\e beeniKimeil alter the discovery ol radiationemitting atoms and in main fields ofchemical research isotopes are used.

In mosi scientific areas, isotopes areused as a constantly necessary lool. Itwould be impossible lo name all ihc ap-plications. Perhaps (he extent of applica-lion can best be demonstrated by showingthe subject mailers ol active co-ordinatedresearch programmes which the Agencyhas instigated. In such programmes, scien-

tists working in dillerent countries—buton the same problems - meet peri-odically, discuss together ami with oilierexperts their findings and progress, andplan their programme lor the near Inline,to assure an economic programme of use-ful research.

Co-ordinated research programmesdemonstrate the main ways whichisotopes can benefit Member Countries.They illustrate the way in w hich mankindbenefits from this research. The numberof participating countries in some of theprogrammes is graiifvingly large. In onecase. 4/> countries arc taking part: in

others. HI-JU) countries arc par-ticipating—surely an outstandingacliie\emenl for ihe IA[!A and ademonstration that a I'N organi/a-lioucan work \\ ithgreat imaginationand extreme el I icieney. Wo shouldremember that the programmeslisted here are only a smallselection of examples whichshow w ha! these ama/ing scien-t i f ic (ools can do.

Evaluation of radionuclides in themarine environment.

62

IAEA activities in co-ordinated research programmeswhere isotopes or radiation are instrumental

NIIIMIUT of countries participating!

Crop production in salt-aftected soilsImproving pasture management

Nitrogen fixation studiesRadiation-induced mutation studies

Improving amrral productionSterile insect technique

Pesticides studiesFood irradiation

Radioimmunoassay reliability studiesRadioimmunoassay studies for thyroid-related hormones

Radio-aerosol respiratory disease studiesImmunodiagnosis of tuberculosis

Immunodiagnostic techniques for human schistosomiasisNuclear techniques for malaria research and control

Diagnostic reagents for communicable diseasesTesting absorbed dose determination

Medical radiation sterilizationRadiation treatment of sewageRadiation fermentation studies

Environmental pollution studiesStudy of pollutant transport in the environment

Nuclear techniques in occupational healthHuman intake of important trace elements

Assessment o! loxic elements in foodstuffsHuman nutrition research

Exploration of natural resourcesSoil water studies

"Tc generators made in small reactorsPolymer radiation treatment tor medical industrial useRadiation applications in medicine and biotechnology

Analysis of agro-industrial products and foodExploration of geothermal resourcesAnalysis of neutron emission spectra

Fast neutron data calculations for structural materialsNuclear data for neutron therapy

Waste estimates in fusion reactor technologyData for radiotherapy

Gamma-ray standards calibration

99m -i

916172843171820412103109551871226113131051079641098146577

63

IAEAinvolvement

Some people may wonder about IAEA involve-menl in the use of isotopes. Isotopes are useful

tools which have (he widest applications in agricul-ture, medicine, industry, environment, and manysciences. However, not only is expert knowledgeof applying radioisotopes in these subjects essen-tial, important related subjects, such as health andsafely precautions, handling, equipment, and techni-ques also must be considered. These are areas about

which the IAEA maintains a co-ordinated programme ranging from meetingsor conferences, lo (raining, the sending of experts, the awarding of researchcontracts, the organization of lecture courses, and the provision of advice asnecessary.

The IAEA also organizes co-ordinated projects covering many fields of ap-plication in specific regions, such as in Lalin America or the Ear East, all of which

64

65

Scientists from some 120 countries participate in IAEA research projects, workshops, spe-cialized courses, and individual training.

arc of great immediate bcnclil. A sample ofsuch arrangements tailored lo the needs ol'aregion are:

Nuclear analytical lcchnii|iies.Nuclear applications in hydrol-ogy .

Sterile /used Icihniijue in liuilfly control.Cereal improvement throughmutation breeding.Radioimmunoassay in animalproduction.Radioimmunoassay in thyroidrelated hormones.

l-ood irradiation loi presena-lioi). and

(ieoiherinal resources.

The IAI -I A assists developingcountries in the Held of isotope applica-tions in main ways. During the lasi 25years, some M300 fellowships have beenawarded, more than u(l(l() experts havebeen sent to participating countries, almost500 training courses have been arranged,some 120 million dollars worih of equip-ment has been donated and more than MI00research contracts have been awarded.

66

Mi>ix- i l iandn ( vav in ni all leclimealassistanee ha-- dealt will) propels whereisotopes were involved, therein acknow-ledging l l ic i i importance lor MemberStales. I lie benefits in the countries humsome o! ihe isotope applications are sosignificant lhal Ibcv can make an imjiael oniheir nalional income, mil in speak ol imprnvcinenis in heallli ami qualilv ol lifewhieli eannol he measured in nioncv.

lleNess and Panelli. who in I'.Mlwere ihe MIM lo ajipl\ naluial l \ nccurrint:railioaeiive siihsiances in seienee. eonklnot p<'ssihls IKHC loieseen ihe wide ap-plioalinns lhal wonkl tle\elop sinee ihen.

i o d a \ . p iae lna lK e \ e i \ h o d \ . nomailer wheie he or she lives, benelils IromapphealKHis ol isolopes a:ul ladial ion.Orinkniii waler in ;i semi-aii i l area ori l r i \ mii a Rolls ko \ee isoiopes ha\epla\ed an important role: o n h . Ihe iireainui |on l \ ol jieople are nol aware ol it.This booklet is meant lo p io\ iile an o\er-\ ie\^ ol ilie \as| ancU altiable uses ol llieselook in e\erwla\ l i le. Il should also sh<>wlhal rathalion is helpiny mil l ions lo havea heller l i le and. in some eases. nia\ evensave lives.

Obv iouslv. as is ihe ease vv i ih othernatural oceunvnees. be il waler. l i re ,

gas. orgrav i i \ . radiation appliedimproperly eoukl spell disaster:but properlv used, il has provento be nl tremendous value lomankind.

A heller umlersiandini; olisotopes ami radiation applica-tions mav help lo elarilv ihemisuiKlei'siamlmusol the impor-tant ro le ihev plav in ourevervdav lives.

As part of an IAEA project inZambia, ground water is sampledand chemically treated to deter-mine carbon levels. (Credit:Yurstever)

67

Written by: Dr. Henry Scli^nianEditing, design, and layout: 1 alcric A. GillvnArtwork: Roland Utncr

International Atomic Energy Agency

PRINTED IN AUSTRIA DECEMBER 1990

IAEAPI A6E