The Tripartite Conferences on Radiation Protection (1949 - 1953)

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Follarlng Is ap nll nl nary report o f the Chalk Rlver Conference p npr d in the AEC Divlslon o f any small dlfference nuy carry $me nuances o f unsuswted signitlcame. It 1s very nearly the same as the preceding verslon but I s now ln~luddI n case CHALK RIVER PERMISSIBLE DOSE CONFERENCE NOTES tolerances with those adapted a t the conference. I wish t o emphasize that this report isa prellmlnary one, and mst not I n rny sense be co nrl de rd otherwise. The plan o f the ccnfaence ws that the k w r i u n delegation, the Brltlsh delegatlon, and the Canadian delegation wwld each n lte avas lon of the meetlng. The three verslons would then be worked Intoa flMl report. The enclosed info mt lon represents a preliminary Wltl - u p of the hrlun venlon by Shlclds Warren's of fl ce in Wshington, and should not be considered as havlq any of flcl rl status 1 have il sol ncl de a i t:bie ccl~pa,ilig tlte ytesact Lus Alas a t the present tlme. Chalk Rlver. Scotanber 29-30. 1941 rm. The attendance ms i s follows: Unlted Klngdon Prof. J. 5. Mitchell Unlted States Dr. Shields wren the chair wer t o Dr. Shleldr YlrThe Agenda for the meetlng i s appended. The "standard man" MIS flrst conridrrrd fra the vlawpolnt of the mass of the organs and tissues. The dlscusslon ms b a r d on the figures presented by H. Llsco i n 1948 (AWL-4253) and these In turn Imludad earlier est l mtr s by both LIKO and Parker (1947) MKK: Report 783. I n the course o f the dlscusslon it became apparent that while sar w nd l q off of ftgures was desirable, nonetheless a reasonably close approproxlrnation t o the actual should be maintained. It ms mphasimd that the tlssues o f major importance were the skeleton, red bone mrm,llver, spleen, thyrold and

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The followfng figures were accepted: Standard Man - Wass o f Organs Skin and Subcutaneous Tissue Other Tfssuos and Organs not Total Body Yefght 70,000 After further discussion these flgures wen unanimously accepted. It nns noted that fl gu rer were glven only for nrles and I t was agraod that t h i s would be regarded as tho standard for the present. Total blood i s minus that mall residual mount which cannot be extracted from the organs. Tb to trl blood volum constitutes 7.71% (5,400 pnr.) o f the total body wight. It i s brlieved that additional data should be obtained rel atl veto all these welghts particularly in the case of the red bone marrow. Secondly. the chemical canposition of the hunan body was considered. T k following values were accepted for the chemical conposition o f the standard man. Standard Man -- Chemical camposition Per Cent Approximate knount i n Hag nesi un Practical Physlologlcal Chemistry, Hawk, Oser & Smnerson 12th Edition (1947)

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The discussion brought out that the figures actually avallrble r n &sed on rel rtl v ely feu analysos and many anal usrre mde ata tfme forty or more years ago uhon the probabflity of errors I n analysls are more flk ely. Moreover, data I s not avallrble dth regard t o many o f the trace elen nts In nhlch ran prrtlcul r rly interested a t the prosent, tlrs pe clf i ull y boron. The neod for accurate data fnth standpoint of elcnantrl analysis hfng.s on possfble t o t a l body Mutron exposures. the Cm ltte e that el w n trl analyur be undwtakrn by organsI that full attention be glVen t o the- ' *geographlc, occupatlonrl and nd l cal hlstory of each subject. the Canadian group with O r . Clprfanl and the V.S. g r w p with Or. Mbrpan. on ovaries should be obtained. It MS further recan*ndad that the data bo given by mass precent and by number of atms per cublc centimeter. It was further suggested that analyses be made on cmPlete hmogmrtes rather than sllces of organs. The thlrd aspect o f the standard mn t o be conslderd YL hfs applied physloloqy. All data suggested below are broad a vm ges of nom1act lv if yin the -rate zone and do not allow for chrng.r caused by abnorrnrl circus trnc r,or other mvirorrmnt. There was a dlscusslon o f the total wter Intake and after s me var lrt ion In vieupoint the following fl gun r were accepted for both water Intake and water output: It ws felt that i n rdditfon to Info mt lon on the chcalstry o f the organs of the mle. data Total Water Intake Total water Output Overall water content o f body 50 llbrs (70% o f 70 kg.) There MSsae dlscusslon o f the importance of the ch mls try of wter I n which food when the factor o f safety was taken into conslderation. i n dry a i r where certaln changes *re nude. The following trbulatlon was acceptd: It was felt that thls should not be taken into conslderrtlon hrreI but should be mlghed I n the discussion on respiration there was general agrement, with the exception o f carbon dloxlde Total surface area o f respiratory tract 70 sq. meters Resplratory Interchange area (upper tract. trachea I bronchloles) Note: The 16 hours "not a t work" Is split up into8 hours sleep and 8 hours Incidental actlvltles. Carbon dloxlde content o f dry rlr The duratlon of occ up atl ml exposure i n the standard M n was considered. and it M I agreed that

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the typlul m n duration o f occupational contact with radiation n u Set a t 20 years for the strndard man. Tk life ti - o f the standard u n was then considered; for purposes o f calculatlon the duratlon of life of the standard mnis az@dtO be 70 y-0. for def ln ltl on of pcnnisslble values of rr dl or c tl ve substrnca vrry M widely as t o constitute a wrkr or othrr medlu. Were other units an 1\01 in uu, Uu value ofuc./cc. oruc./g. should k follarrd i n brackets by Its equivrlmt. A nukr of tinu I n the disc w sim on the standard man, questions wlre ralsld as t o whrther own wights or el v n trl corp orl tim should be considered as nv x in r o r mlniNli rather than as nw n rights In order t o gfve a fact# of safety to radiation dow Calcuhcorporated I n the datr used f o r brslc calculations such as I n that glven for the standard man. a t somc length. Reference YS M de to UR.67 as OM source of bsic data. part l cula k matter varied gr rat ly In $11, and i n solubllity. It was notad that pr rti c trs of UP o r less i n diaaeter, or Uranyl nitrate particles of 4 Y. or less dl-tar, were hravllY mt afd in the lungs. That i n the use of UF , those particles o f 0.5 Y. fn dl meter uen retainad three tim as much as those 1ml cm in dir w fer. brought out that Jol chl s thal miners developod lung Cancer not i n the alvcoll. but I n the koncfil, and after a man occupational exposure o f 17 years, Si klaSS d that radon 11*s the chief hurd and Or. Mitchell nvntlonrd claculatfons he had made which indlcate that these miners had got the equivalent were retained i n fhr lung initially. but 80% rpprarrd I n the feces i n the next 48 hours. dfscussfon the fool tawhg recDaMndation was unrnlnarsly adopted: re k ntl on would be considered t o be 50%. for insoluble part lc la, 50% nwld be asstmad t o be trapped and remain i n the lung for 24 hours; after 24 hours. 251 o f inhaled Insoluble partlcles would be considered t o be retained. I n con unctlon wlth thls phase of the discussion, then YS consdierrble dfscursfon o f the hurds o f radioact!ve partfclrs. It was rphrslmd that radioactivity invalvlng nl at lvr l nlnute MSUS o f tissue don not have carcinoqenlc effect cap rr able to that of rad lrt lan lnvolvlng !awe masses of tls - wlll be roughly spherlcal. radiation measurement Instruwnts i n use a t Chalk Rlver. sesslon o f the flrst dry's meeting. The def in it lon of the tm relative blological eftactiveness was considered. It wrs agmd that thls referred t o the ratio bet wm thr quantity of differ rn t types of radiation (measured i n ergs./gru) requlrad t o produce s- biological effact. It was pointed art ttut the relative blologierl effectiveness o f any given type of radiation may vary for different bio lo pic rl nrc t lons and for acute and chronic fomof the sua response. After considerable discussion it WIS agreed b the rnrben of the citt ee to regard the effects of rad l up ~ l ~rays (filtered by 0.5 m. pl rtl nun r as unity and t o compare a11 other marsurcncnts of relative b lol q ical effectiveness to this value. An objection t o the use o f gama ray effect as unlty was baud on the fact that most o f the data about chronlc radiation effects on thr bone marrow YS wind by ob s rv rti on of persons expos& t o 200 Kv x-rays and that the rel atf ve biologlcaT effectiveness for this response of gam rays and x-rays has not been detenwlned experimentally. The rmon for chooslq raditm i n spite of this objection uas because of the convenience and r ella bill ty of radiull sources and becausa of their wide acceptance as radiatfon standards. It was agreed by the cait tee to consider the relative bio l ~ lca leffectfvmess for the bone marmu effect o f radium gama rays and 260 Kv x-rays a s 1:1, while that f o r acute skln effects Is 1.5 IS ha$ been shown experimentally. different types o f radiations was approved by the Conmittre. It ws unanimously agrwd that ufety factors should be c lwr ly labeled as such and not i n - In rel atl on to the standard un, the retention o f partlculate matter i n the lungs Y S considered A considerable discussion o f the radlation hazard from exposure to Urrniur followrd. It Y S Or. Hunilton cited a case of Yttrlum oxlde inhalation where 001 of the particles from 0.1 t o 1 U. I n calculatlng re k ntl on of particulate awosoIs, i t uas accopted that far soluble particles, the In view of the importance of particle shrpe, f t ut11 be as sued that the particles o f Interest Just p r i o r t o the noon ruess. the conferees inspected with much interest the various types of Item Z--Relatlve Biological Effectlvenesr: This subject WIS dtscussd during the afternoon The following table for the rel atl ve biological effectiveness for bone mrrw and skin effects o f

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The tena fast and slow neutrons In thfs table anusd In the fol la iy arbitrary Hnse according t o the aim ment of thr C alt toe : Fast mutrons a n those whore b lolo gl ul action I s due prlrwrlly t o proton rr coll rf fact while $1- neutrons are thou thou action on tis - n rul t spl url ly fra nucl wr reaction. f hip rl ncl1 change I n the valbes tor nl atl ve b lolo g lal off rtl ve ~ m s roccurs I n thrt for or lg ln ally vrrurvd by %tie. I n v1m1 o f Um went data concrrnlng the gmrter bio la ol ul effutlvedosage bl f vera d to art al ncr lt lol tissues uhlch appear to be most easily drugd. Thls concept MI aceaptad by the bnrlttee. (See Agrement 1.) and some of the dlscussfon on rCllch they were basad 1s w nt lond. tohrd x-rays o r gum8 rays. *fie the skln i s to ba conridend the cr ltl ul tissue f n the UU Of Sdb Th ls is In agn rant with the proposal made by Or. Fallla In hls pr r ll ll lln ry report. Owe to the blood-forning organs caused by over-exposun fo prnrtratlng radlatlonr wrap rr lod of my pars Is mnlfested by the developrnt of laukmla, whlle eplthelfars are the end r e s u l t of skin overexpasure. I tulsa gm d for purposes o f health nonltoring Uut thole body r rdi atl on should n ~ tnrll yk asswed f o r any radiatlon exposure other than t h a t known to be lirltad to thr bndt a d fWHmS. I n the course of the mlng dlscurrlon about pmmlsslble exposure t o utrrnrl rrdlation, It ms 1. It WIS agreed to regard tk blood-fornlng organs as the cr ltl ul t f ssw vhen the body 1s exprrd It was declded t o exclude diagnostic and therapeutlc exposures t o x-rays frm this dlscusslon. I t YIL poln td out I n the discussion that blood fornrtlon I n the lllm taka place I n both the I t was agreed th&t for purposes of calculation the average depth o f the blood - fm lng tls swr should be considemd t o be 5 QI. below the skin surface. flat bones and I n the vertebral bodleg with ll t tle active blood f0rut lon no null y trkfng place in th long bones. ttu average dqth below the body surface o f tk IIY ~o f the rlbr and o thr flat bones YS est ln utd by Or.Wren to be approxlwtely 1.5 QI..rCllle that for thr vert rb nl bodles MI thouqht t o bo be- 8 and 10 a. The tlgun 5 Q. represents a gwss d l c h I s ktd on the two VrlwS glvtn above and on the proportion o f blood-fonnfng tlrsue rst lw td to be present i n each. I n the course of thls dlscusslon the q w st lon cm up as t o Aether Irradlatlon o f part of the bone ~ URR Iws as serious as exposure of the rntln bone Wrrw Insofar a t evrntu81 dw rtop s nt of la uk n la fs concerned. It wls pointed Out by Or. Warren that tcute locallzed r a d l r t l o n of UP to 25 per cent of the marrow d l d not …