Document QOkqk74ML8aV0JpQdOovG0ko

Ji January 4, 1946 Mr. T. R. A. Be van, " - ; The Associated Ethyl Company Limited, Artillery House, Artillery Row, London, S. W. 1. ... ... U`** .&<5*.* *sg-\ Bear Ray< Quite some weeks ago In letters dated August 21 and September 21, ; I received from Fossett analytical data from Abadan as forwarded . by Mr. Harrison. Fossett*s original letter of August 21 was : accompanied by a letter from Mr. Harrison dated July 26 in which there were a number of comments and. Questions, which I have attempted to deal with in a memorandum which you can deal with in accordance m with your best judgment ...... ..... -- -- TM .... - I regret that it has taken me so long to get around to this matter. However, there have been so many things to do that I have had to take them in accordance with their apparent urgency. I hope you ? will be able to convey this to M r . Harrison in such a way as to indicate that X have not been unmindful either of their interests or of their very splendid cooperation. It is rather that I have not solved the problem of being in two places at once or of doing^ two things simultaneously* Perhaps the scope of the memorandum, attaohed herewith, will both explain xry. delay, and make amends for it. , With kindest personal regards, Sincerely yours, R AH e f .... iA Enc. : r rt. Copy by Air Mail. . ... Rober t * hoe, M. d T X V&Z&:- lx H'.: * ^ "f"' *" V1 " f\ J .! Vj rl " t-K#' \(B . 0 0 . 1 0 ZX -r-:% -% l VST MEMORANDUM ON REPORT AND QUERIES FROM ABADAN *V' ->*!. ,?-S- * Lead Exposure Associated with Various Occupations -r?^V ' ,% The data obtained by the Analysis of the urine of workmen..;^ r- have been examined, and various aspects of the problems Involved, a s & X raised in Mr . H a r r i s o n 's letter to Mr. Fossett dated 26 July 19^5# - ^ ^ - % have been considered .; The data are set up in tabular fonn herewith J for illustration and comment, but.the .several occupational groups are referred to separately for greater clarity, r y . iH ' 7 .. 7. '777'-.,-,r-V' ' " 'IP* - Distribution of Analytical Results Obtained Upon Samples of Urine of Various Groups of Workmen at Abadan in 1944 and T P 45 Urinary Lead Concentration Mg./L ..." 0 - 0.019 .02 .04 ..... .06 ' ' .08 - - .10 .12 -- 7" -7' 14 , y. .16 - - K .18 .20 .22 .24 Frequency of Occurrence of Analyrtlcal Results within '--.M Limits Indica ed , ' 1944 SEB v Entire Nov. and Dec. DF .-V TPA 1945 '-3; SEB DF TPA ' ' -i. 0 ; 1 11 19 2? 4 13 21 7 3 1 1 1 4 1 2" 5 9 ^ 2 1 92 62 68 ' ' .. 3 6 .5 2 12 !-:7` ;r-'>V `' 4, 3 1 . ; ' >' ' - 2- 2 ' *\ 1. 10 6 -, 2 y12 10 . ... 2 2 1 , .2 4 6 ....4 ... 8 7 2 A- ' . 1 7 6 4 3 7 3 .' * Total f - fJ-: . 105 M ean .. 777-., .* 0.092 P.E. - so.ooj S.D. * o .046 C.V. { $ ) - ; 49.74 24 0.111 0 .0 0 5 *0.035 31.89 -V j q -- 0.0677 0.004 0.034 5O .2 5 * 44 ^ 0.120 0.005 67o49 7 . 41.06 45 0 .0 99 0.004 0.041 41.07 34 31 - : 0.092 0 .0 92 0.004 o.oo4 0 .0 36 0 .0 36 38.87 39.21 Mixing Plant Personnel -- ** *-- V . V.v- 7" ~vf S/.- */ The group of men engaged in mixing Ethyl fluid with gasoline deserve special attention in view of the1data and the question raised , as to the accepted limit of safety 7y f ' ,. .. ' 2. . ... . .. " 1. The data on these me n (Class S.E.B.) demonstrate \: clearly that some degree of occupational lead absorption Is occurring among them. The comparison of the available data for 1944 vith those, for 1945 shovs that no significant reduction In the lead exposure: r : has occurred during 1945, even when one employs the results obtained ; only for the months of November and December of 1944 (by which time -J;` : , " - ' ; . " most of the low results due: to the Introduction of n e w m e n with no *. V prior occupational lead exposure during earlier months of the year, were eliminated, ^ y.y----- 2. Examination of the results on individual men for the year 1945, show that eight members of the group have provided more than one sample with a lead concentration in excess of 0.10 mg. per liter (Case 95, 129, 150, 1 4 1 , - 1 4 2 / 1 4 5 , 152 and 166), and that these men appear to be more or less consistently high in their rate of lead excretion. One (#166) had two dangerously high results, while another (#15 2 ) had the highest of all (0 .52 mg. per liter), followed subse quently by a lower but significant result (0 .15 mg. per liter) . ;j? There may have been some factor of contamination to raise the general level of these results, but one may not safely assume that this was the case.- v-j'i-'sv.i*.. '.. ", V . 5 The question of the tolerable or safe limit of lead *14 exposure, as expressed in terns of urinary.lead excretion, appears not to have been fully understood, and in a subsequent part of,::this::^^fs;^ memorandum I shall attempt to clarify this matter and to give advices on die application of suitable criteria for the disposition of ,- * individual cases. However, this is not the point involved in the operation of plants in which Ethyl fluid is mixed with gasoline. . Persons who work vith Ethyl fluid in its concentrated form must be protected against lead exposure* Unless they are protected completely. It Is not possible to be sure that,they are protected at all, for the rote of lead absorption as the result of contact of the skin vith Ethyl fluid or because of inhalation of vapor,, given off from the concentrated fluid, is so rapid, as to be excessively dangers o u 8 . Errors of technique or judgment,^therefore, may have prompt and serious results. Accordingly, a ,,.regimen of precautions,, in the form Vi of suitable equipment and detailed instructions, has-been provided, ^ which has as its purpose :the avoidance of all exposure and all ab- . sorption of lead. Moreover, evidence of lead exposure and absorption on the part of the workmen, is regarded as evidence that the mixing ^ equipment is inadequate, or that the instructions are not followed properly, or that both of these factors are involved. When such evidence is available every effort must be made to find the faults in performance and correct them. It is not a question, therefore, of . how long a man can work in this occupation, or when he has been exposed for a period sufficiently prolonged to be dangerous* It is rather a question of whether he has been trained sufficiently (or well enough supervisedJ in the performance of his duties so as to avoid lead exposure. ^ Recognizing the fallibility, of man', some provision has been made for offsetting the effects of some slight defects in the precau tions. T h e r e f o r e , ,the periodicity of mixing operations has been ^ - r e g u l a t e d . T h i s regulation has. certain other purposes# however, which are more important than the spacing of3 exposure. It a l s o has a ten dency to determine the character of the mixing equipment. Our reasoning in this regard takes the following line; - if.it is necessary to mix more frequently than six times per. month, then the mixing . equipment is not of the type best adapted to the purpose* In general *- 4 our experience fully justifies this conclusion. Therefore, (to answer another question in M r . H a r r i s o n 's letter), the duration of : an individual mixing operation is not a primary consideration, and ve are not in position to take it into account. We must insist upon ,-V -h*-.r 'v '-> X-rti the importance of the avoidance of lead exposure. If that is done < the length of this time is unimportant Moreover, it is not our general practice to make use of multiple groups of m e n , so as to ti; s. limit individual exposure* Instead ve insist.upon changing to a type of equipment that requires no limitation of the frequency of V mixing* . , .. It is recognized that these principles are not nov applicable In every respect at Abadan. A large volume of fluid In drums must be handled, and the long time and the frequent repetition of. this vork introduce some degree of hardship and discomfort into the work of the men, as veil as some tendency for relaxation of precautions. This elsewhere, at least in the U * S . A *,would, be counteracted by the adoption of a new type of mixing equipment v which would enable the Ethyl fluid to be handled in bulk under conditions which, during 'rl mixing, would entail n o opportunity for *lead, exposure. The one most Important principle, however, does apply at A b a d a n , and indeed, is y all the more imperative, - namely the principi of complete avoidance :~ . of lead absorption. So long as we cannot apply the orthodox solution of this problem, in the form of new equipment, it is" necessary ' . . ... ; every other means for the avoidance of exposure be emphasized. this reason, the use of multiple crews of mixing personnel was that -: For ^ x ,s 7.. Yft approved. .r/.v $. ;.. F o r the above reasons, the relaxation of the standard of "S safety as expressed in urinary lead concentration, in this occupation, KE 0010303 is not good p o l i c y 1o r practice . What I said of this originally i a -c., Abadan in relation to mixingV vas that lead concentrations in excess of o.lo mg. per liter of urine vere almost certainly indicative of. occupational lead absorption, even though there; vere only a few v-f results to go onV and as such vere to be regarded as dangerous not in themselves, but rather beoause they demonstrated.failure, of the precautionary regimen. This1is true-; h o v , as it vas then'. \ The ->.: criterion of "safe " versus hazardous^ lead absorption (to be discussed later). Is applicable in industries in vhich there is a slight or moderate, conventionally controlled hazard. ^It<is not applicable to ; this occupation# in toy opinion. Kather, the evidence of lead absorp tion on the part of these vorkmen, is proof that the entire operation needs better and closer supervision or.better equipment and operating .' . / methods. It is a sign of need for improving the performance, not for changing the program of medical handling of the m e n . . , . Drum and Can Filling Personnel It is obvious that vork done by these men involves some de gree of almost unavoidable lead exposure, vhich, hovever, can be - ,>.:; *. lio tv3V. r S' i-j.-tx accepted vith a degree of equanimity because of certain factors vhich operate vithout fail to dilute the exposure and to make it less than immediately h a z a r d o u s . ((l) The dilution of the lead compound , ':r- ' . * ' 1-^ i>-V' V. .-V :'v *..: - v vith gasoline reduces the danger of fatal skin absorption of T.E.L. to the vanishing point, and decreases the volatilization of T.E.L. in Cs:',xX:'rfo-- . !-' V'Ki' .;V ?;!'$. an indirect manner. (2j The presence of gasoline liquid and vapor, f t g g f h ? >* 'v *. i. introduces other obvious risks (fire and explosion) the control of vhich tends to reduce greatly the lead e x p o s u r e .) One is not likely to be poisoned by T.E.L., therefore, in these occupations, as the result of an accident or a technical error that gives rise to a 6. brief exposure. Poisoning if it can occur under existing conditions results from relatively prolonged exposure vhich therefore provides' time in vhich to appraise the situation and to take appropriate action It is in such a situation that th level of tke lead excretion of < groups or individuals demonstrates that the sources of lead exposure o;* require better control if conditions are to b e `safe for indefinite ....... . , .............. , . rHt:y;: ' :V--' '-h's periods of employment or alternately'that an individual'needs to be removed from exposure for his ovh safetyV k In dealing vith problems of this type ve have found by s experience that if 1th e 'stable mean concentration of lead in the urine of exposed workmen does not exceed 6.10 mg. per liter, cases of lead poisoning vill not occur. This same fact applies to the individual if there are a sufficient number of analytical results to provide a stable mean value for the expression of his actual physiological status vith respect to lead absorption. (This Implies,of course, that the lead exposure is fairly veil controlled and not subject to vide variations from time to time. Othervise stable mean values could not be obtained.) This standard allows for certain variations above and belov the mean, and does not require that a man vhose urinary . ::- lead concentration in a given instance.is above the mean value, is J^ to be removed from his employment. On the other h a n d , the standard j;:': itself is factual, and as such is not.subject to modification to meet ^ '..... " '.... " .. ... a given set of practical conditions.:; / ':v; .* i: X ....... looking at the tabulated data from this viewpoint, and assuming that there is n o factor of contamination to elevate t h e ... individual results and thereby the mean values, the following conclu it: sions are justified;, , t :y-y ....-! .... . ; V; .... ve- .i :i';*3>ihe lead exposure associated w i t h drum and can filling vas kept within saf limits during 19^5, tout vas just at the threshold of danger, Le. there is no large factor of safety. ^ 2. If, however, conditions remain as they are, it is-i = possitole that the factor of time and lead accumulation in the tissues of persons who remain in their respective occupations, will cause the -- C V -5 w . y V > ^ * jj. ' . ' \ , ,`v v . \ ( **t- ,, -r mean values to increase to levels that will then toe unsafe. vi.* Xivt c-4-s.^iV i.StOKi.d-.PS'-. 4 . 4 v f J V r o v r ? '* (Vie have previously discussed the special factors in Is --i*'* V V ^ f v C--.-',f-a!v. connection vith the mixing of Ethyl Fluid with gasoline, which negate the conclusion that this occupation is safe, or, at least, that it would toe so considered under the usual conditions of unsupervised work, that normally characterize this work in various parts of the world. However, it can no w toe said that if the supervision of this work is or should toe sufficiently precise and continuous so as to prevent all highly dangerous exposure to T .E .L., this same conclusion is applicable here, as it is in T.E.L. manufacturing plants, where supervision is continuous> and where the training and discipline of operating personnel is kept at a hi g h level of q u a l i t y .) \ Criteria for the Medical Handling of Exposed Personnel - -^ Over the years of observation and-study of conditions and personnel in manufacturing operations, criteria have developed which enable the physician to determine hov^to deal with the several situa tions which arise in connection vith the safety of individuals. The special conditions of the war-time manufacture of tetraethyl lead have given to these criteria a precision that was formerly lacking. It is to toe remarked that there is no large factor of safety in their application, in view of the fact that shortage of men in the manu facturing plants was responsible for the exercise of the most conser 8. r * V 't V >- vative judgment in the removal of men from their employment. At the r'>..* :& S same time/ it may he said that not even the necessities of war vere believed to justify the acceptance of undue risk. On the part of i./ individual workmen. Therefore, these criteria are advanced with ` .. .<>v-'"i some confidence in their validity. V>, h : . - ' i. >*..1 V,,i^ ,-y, 1. W i e n analy. tical data are avai.l..a...b...l...e....f..i...n... the symptomatology of any type, *- p re..s...e...n.. c . e ,.. of - . . . `"*v Xr-*.-; U.Vv &2M. ' a. the symptomatology; should be interpreted .without r e f e r e n c e ^ ftort acwnanllyvtf i4cAadli idlafltfa11 aornifd^ ,afi' "concluuesfiAonn aavrivri4vtfAed4 matf darsf't+o^-'1its ^ ^ . significance, taking into.account ..the hematological and other laboratory findings; v'?yV V,. b. a cause and effect relationship between lead' absorption and non-specific symptomatology, on the part of men who have been working up to the time of sampling, may be 'excluded ,.when ';;,v;^ 4 (1) the results on a sample of blood and a spot sample of urine are well within safe limits; i.e. - less than 0.06 mg. per 100 grams of whole blood - less than 0.IS rag. per liter of urine; or when ( 2) repeated results on spot samples of urine are within safe limits as defined above, or when ; . (?) the result on a large sample of urine is within safe limits as defined above - . - - . :S; *l '.v a cause and effect relationship between lead absorption and non-specific symptomatology.may be assumed to exist, !..W...h.en... i*t<;i./t.v' 1_ s .'>- .'*$- -- .,s : , . ..., r-ii- -.: , .J.'-vi*Y.''.;,Cii . (1 ) other causes" of symptomatology have been excluded beyond reasonable doubt end the analytical results are above safe limits; or when :; (2) the background of. the symptomatology is quite un certain, and the analytical results are within the dangerous range, i.e. - 0 .0 8 to 0 .15 mg. per 100 grams of whole blood 0 .18 to.0.40 mg. per. liter, of urine. ,,,,. . . . . - ... .... , 'y-'t/v; t * . d. a cause and effect relationship, between lead absorption and strongly suggestive or specific symptomatology may ; be assumed to exist, '(dien , > (1) .the analytical results are within the dangerous ` range; or when . iv (2j it. is known that the analytical results were well above safe levels during a period of lead exposure that has now been discontinued, for some weeks.  Y;\-. 9 2 . When no symptoms of any kind exist# persons should be removed from lead exposure or transferred to work involving greatly 1 reduced exposure# when V". -w- a . the analytical results are consistently vithin dangerous limits# i.e. - ... . V. *vfi ' (l) results on a blood sample and a spot urine sample' ..I ' '-are in agreement at high levels of more than 0U O 8 - mg. per loo grams of vhole blood and more thanl, l o . l 8 y ^ . mg. per liter of urine# or v-; . rr;4 '(2) repeated results on spot urine samples are consistehtly/j within the high range indicated above; ior-* V \ k '; 6 ) the result on a large sample of urine is withln ithe ? t range given above (0 .18 mg. per liter or m o r e ) . > (Ah';' exception may be made in this rule when it pan be'" established that a high result is of short duration <<, ' and is followed by a rapid drop in the results# as; , in the case of brief severe exposure.) r?- - - ' "i .i 3* M e n with no symptomatology m a y be returned to the work frod]i \ which they were transferred or removed because of excessive',; 3 ' lead absorption, when -pty. " " :- V :j a. the analytical results have fallen to l e v e l s 'that are consistently safe, i.e. - U) ( 2) i?; the blood results are down to 0 .0 5 mg. per 100 grams or lower, and the urinary results are not higher than u.lo mg. per liter; or the results on urine samples of large volume (one liter or more) are not in excess of Q.lu mg. per ... liter# and a representative sample of feces for a twenty-four hour period contains under 6.4o mg. of lead. (In general, the length of the period of re duced or discontinued lead exposure should be more extended in the case of persons whose employment under conditions of potentially hazardous exposure c has been prolonged# i.e. the longer the period of ^ exposure# the longer shall be the period of freedom from exposure. ." - J* '-P V3*'.'' Masks for the Protection of Mixing Plant Personnel against T.E.L.Vapor * Previous discussion of the hazards of mixing have dealt with the need for additional precautions. W i t h respect to canister masks# additional comments are justified..5 " -rr The standard prescribed In the instructions with reference ' to the length of use of canisters (l hours) has been set up in ' relation to the somewhat diluted vapor of tetraethyl lead only. It 10. ; i''S ' '-'tl'f.- ha s no application to gasoline vapor on vhich ye have no valid data. 1 In mixing operations, as ve are generally familiar vith them, the A >; ;l problem of concentrated gasoline vapor is not encountered to an ' important degree,'and therefore ve have not attempted to deal v i t h v<' If M it, in the belief . . that technical .. and .. medical personnel 'a..;-..i . *X In - the y p.4etro-' t "' leum Industry have had more experience vith it than'have oiirselyeyf It Is know however, that moderately concentrated gasoline v a p o r y _ will flood a canister mask and render it ineffectual after relatively brief periods of use. There is no means of dealing with this problem..., ' * , ^ r except experimentally. If and when exposure to gasoline vapors occurs i ft,*. to a significant extent in association vith mixing operations, standard ' ' ' ....... fflbfii will need to be established and put into effect to meet the actual1,;-s..,v-m 'N'45 Vfconditlons. If possible, it is veil to deal vith the gasoline hazard'll Ias an entirely separate problem, and to limit exposure to gasolinef = in mixing operations to such an extent that the masks used against tetraethyl lead vapor will be directed solely against that hazard. If this cannot be done,ja period of use of the canister will have to be set to meet the requirements of the most concentrated vapor, that of gasoline, In the mixture of vapors to vhich men are exposed. Cumene The toxic effects of exposure to cumene have not been fully ^ investigated, so that sIt is not possible to set up a standard of safety for prolonged regular exposure. Vork is under way at the . :-v National Institute of Health in Bethesda, Maryland, .S.A., but has i- not been completed. Information on acute effects is available and a - ' . C. ' .. ' ' copy of a reprinted publication is enclosed herewith. It seems pro- . . .. V- .. .' - - . - S bable that the concentration of 50 p.p.m. is reasonably safe and it; is not surprising that exposure to concentratioiB of several hundred * II. rtt parts per million caused difficulty. - ' . . ' ~ *v The observations made at Abadan are of great interest, and the handling of the problem as indicated. , .-j <:;f`rts5 is cause for congratulation. ,';>h' .... Signed: 1 Robert A . Kehoe , MVD.V Chief Medical Consul tan Associated Ethyl Com; cc 5 KF 00103A0