Document text
Machine-read from the scan, so expect some errors. Lines that couldn’t be read are left out.
Page 1
Department of Bio o he ds try Meharry Mediwl College ear Professor Wests Thf8 i s in response to your letter of July $1, 1947, whioh 0while I was out of tam, requesting my opinion ooncerniag the u m of Oak Ridge, radioaotive Iron having a speaifio a ot iv it y of 0.15 om FeS9/gm plus 0,17 ma F&S/gm ina study of iron uptake i n loo0 oonaeoutiye admfssions t o the hb bard Hospital In 1Pl8hvill0, under 8upporf by a grantIwill as8ume the oaloulations whioh follm that YOU intend t 0 administer this radioaative iron orally. We will Bee that the tis rue radiation dosages a r e so 8 1 ~ ~ 1 1that the general oonoluaion to-!*he effwt fhat this radioaotive fron in per fe otl yr rf e for your experimaaats would. nut bo altered if you administered t h e material intravenously. Let us assume that the iron dose add n fet ers d to eaoh pafie& 5s suoh that the apaxh observed uptake i n any patient is 8wh as t o pFoL t o the beta ray8 of Po59 as deteoted by Geiger-Miller oountera whose radiation doses are deroribed i n the paper on "The Use of 'Rro Radioa at ive Ieotopes of Iron i n lfrnoer Studies of Erythrooyber" by Peaaoak. 608415 (1946), a reprint of which is enclosed. Suoh oountem, and o aloda t ions of the f~88Ue:: Robably Pew if any of the patients xhcnn you rill study dl1 h v e aotivity of Fe' would oorrespond t o about 400 opm per gm of whole blood in the patient * s airoulation, and this would oorrespand t o 1600 d is in te - grations of Fe59 per minute per gram of whol& blood. The average anerg of disintegration for FeS9 is 0.12 x lo6 eve Then the dosage due t o Fs h the oixpulating blood would be about 1600 x 0.12 x lo6 ifioantly greater than 40 per aent. Thus the mu4nnna The additional blood dose due t o FeS5 wfll oOrre8p0nd t o Repository: NARA Atlanta Archives Folder: Tolerance Levels
Page 2
S o the additional dose due toFOE Would be about: 0.252 I. 104 r/day. This Fe55 dosage is only about 1/20 of t h e dosage due t o Fe59, as would be expeoted frmn the appr a x wt ely eqaal abtolute aotivity of the two irotopea, oombined with the faot that the averqe energy of dia Weg ration of FeSS is only about 1/20 that of Fe59, The blood dosage duo t o Fe55 is therefore substantially eq ml to the whole body dwgr due t o oosmio rays and looal gamms radiation, whloh isat be given t o that portion of t h e absorbed iron uhioh may bo present lauaole myoglobin, re- iron-binding protein (61 globulin), and t h e In addition t o this hemoglobin ban, oonrideration should a160 ferrat in md hemosiderin the erythropoisfio system, adult has a bone mrrm apaoe ranging from 1600 t o 3700 p, averaging engaged in t h e formation of erythrooytes and leukooytes. Futhermore only one-fifth of the aotive bone m ~ rro wspa00 is oonoemed with erythropoiesis, the other four-fifth produoing white oells of the myeloid series. Lsrmphoaytes are not produoed i n t h e bone DBFFOIC but in the spleen and lymph glands for the most part". average adult about: 2240 gar non-erythropoietio bone marrcrrr Only one-half of this murrm is a ot i veh the senre that it $8 This gives for t h e Studies of several hundred individuals by Gibson, Finoh, and other members of OUT re a evo h team have shm fhaLt in the nonral adult abod 80 per o d of the absorbed iron is in the red oells, and about 20 per o a t is in body stores probably divided r o that 15 per oent is i n the liver and 5 per oent is in t h e remind9 of the body. We can then make an estimate of the maximum bone LtlLLrrmr radiation dosage by taking the extreme assumption that this 5 per oent i s all inthe m138 of the erythrooytes, and contains 5/80 = 1/16 as muoh t o t a l iron, then the radiation dose which this W l mass of erythropoietio mamcw dosage oaloalated abwe f o r the whole blood, or: 8 x 10- r / b y for E'e59, If this tissue has 260/6000 or about I/& the 8 8 might imagine t > A t a l l t h e &beorbed iron (instead of 5 per oe& of it) was permanently deposited exclusively i n the erythropoietio mrrm, the dosage would be 20 times as great as these calculated values. This would
Page 3
Professor H. Do Weat 4- rugwt 2 9 , 1 9 4 1 taken as 100 x 1 0 4 r/day8 and that Fs59 has a half live of only 47 days, I feel %hat the use of this mixture of iron irrotopes will be psrfeotly safe for your patisnts. t o produoe only a radiation level which i s oornparable with the cosmio It should be pointed orrt that the tentative (July 21, 1947) Standard h n being oompiled by Dr. &lpaan Lirco gives apllm bone narrow space of 1500 gm, and a red bone 111c~mmspaoe of 1500 Gm. This i s about 6 times the erytbropoiefio bone mrrm spaoe (260 gm) assumed in the abuva oalrmlations, nhioh may therefore be an over-estimate of the bone ~ ~ II TO I IT dosages by as moh as a factor o f six. on the strength o f these quantftdtive estimates, I feel you should have no hesitation in goint ahead w i t h your projeot. Provessor of Physioe