Document km94Kxwp2ZgkgZzQbDGbrDKMb

'KS8SS* %cdef(LM c0' Jan. 18,^1937 Dr. Robert Kehoe, University of Cincinnati, College of Medicine, Cincinnati, Ohio. Dear Dr. hehoe :- I can see from your two reports that you are greatly concerned about the possibility of contamination of specimens. In order that you may judge as to this possibility, I an going to give you the exact detail of collection of specimens on both of these employees. Both of these men were called in from home and v/ere not at work, consequently were dressed in their street clothes. ' The urine specimens v/ere obtained by me at the time the blood was drawn. I do not see how I could have been anymore careful in preventing contamination. I held the bottle and capped it immediately so I do not believe that any dust could have fallen into the bottle. With the blood, the arm was scrubbed thoroughly and I used the exact technique you specified, and in addition used rubber gloves previously sterilized in distilled water. The tube is held almost ho r i zontally so that even though there was dust in the room it could not have fallen into the tube. It was not necessary to re-sterilise either of the needles. These tubes were immediately capped and shipped to you. The only source of contamination that I know of would have to come from the dust in the room atmosphere. We are going to have dust analysis made very soon by the Detroit Testing Laboratory and I will have them include the dispensary. In the case of WUItKtkI H T we had gastro intestinal symptoms, pain in epigastrium, constipation, loss of appetite, and some muscle cramps coupled with a rather low stipple count (22 per 50 fields). The clinical findings indicated a dangerously high smount of absorption, and your findings confirmed that opinion. He was sent home and the samples were taken after 2 or 3 days rest. 0005500 - 2- Dr. Robert Xehoe: The samples on C. Bagrowski were sent, not because of clinical findings, but because our stipple counts were running so very high (205 per 50 fields, yours at the same time 37). We are wondering about this discrepancy. This boy, I found out recently was treated for a specific urethritis last summer, and has been advised to drink a large amount of water, which may account for your low lead finding. The blood lead is consistent with the exposure and our very high stipple count. We are , at the present time, enlarging the dispensary and the Factory Manager says that he is going to air condition our rooms, filtered, humidified and tempered air etc., so that will surely reduce air contamination. Until this change is made, and in line with your suspicion of air contamination, all samples will be collected in the Main Office. Let me have your suggestions as to any further improvements in technique. Was very sorry to hear of the accidental death of your associate. There was quite an article in our morning paper about this unfortunate occurrence. Thanking you, I remain, PHH-ec Sincerely, MQrdJLA Paul M. holmes, .i.D.' KE" 0005501 BUNTING BRASS AND BRONZE COMPANY Toledo, Ohio A Study of the Lead Exoosure Associated with the Operation of a Plant .B eari rig s & / 4,4* -Tb J, JC J tur,ed tf M f* r by The Kettering Laboratory of Applied Physiology in the University of Cincinnati Cincinnati, Ohio Robert A. Kehoe, M.D., Director. K 6" 0 0 0 5 5 0 2 Introductory Comment on the Study of Occupational Lead Exposure In vie of the fact that the general methods of plant study employ.ed b y the Kettering Laboratory of Applied Physiology differ somewhat from those used generally in industrial surveys, it m a y be of some interest to refer to the available methods and to point out some of the advantages and disadvantages in their use. (1) A single critical inspection of operating conditions in a plant, made b y an experienced person, will provide a general idea of the opportunities for lead exposure and some knowledge of the location of the greatest hazards. Periodic in spections of this type will prove to be more useful than one for obvious reasons, and moreover they are a useful adjunct to any other method of study and control. (2) A single clinical survey of groups of workmen representative of various occupational activities in the plant will define the general levels of lead exposure in terms of clinical evidences of lead absorption and will tend to the most hazardous types of employment. () Maintained medical supervision, with periodic examinations of all employees and with carefully recorded information as to the character and incidence of illness, the amount of lost time and the extent of the labor turnover, will eventually show the hygienic significance of plant c o n ditions^as no other method can do, and if'^C h^aatar'are ctombined with detailed knowledge of plant procedures^ -2 't&P ' including changes in equipment and plant practice, a clear composite picture of the hygienic situation can be obtained. All elhe-r-moans 4 evaluating the hygienic significance of lead e xposure, a? con--- ' depend upon sound clinical data. Indeed the belief is well entrenched in the medical as well as the non-medical mind that individual susceptibility to lead intoxication is extremely variable and that even the smallest quantities of absorbed lead may, in time, result In lead poisoning in certain persons, while certain other persons ma y receive no injury from massive dosages. The complete acceptance of such a point of view, (which in our judgment is erroneous), implies that there is little or no value in any type of measurement of the quantity of lead absorbed or potentially available for absorption on the part of workmen. So long as such an opinion is applied with even partial effectiveness in medico-legal and trade- union phases of industrial practice, business management cannot afford to operate plants associated with any of the lead trades without com petent and adequate medical service. Fortunately, evidence has accumulated to demonstrate the existence of a relationship between quantity of lead absorption and the occurrence of lead intoxication. Various expressions have been given to this relationship, and it cannot be said that there is complete agreement among authorities as to the safe limits of occupational lead absorption, nevertheless It is now fairly generally accepted that there is a limit of lead exposure above which the.danger of lead poisoning becomes progressively greater among a plant population, and below which cases of poisoning will either not occur at all or will be of an essentially harmless type. Thus it becomes feasible to estimate the significance of lead exposure in quantitative terms. - 5- tuC&L t^-vJ (X^c^LalZZtO (4.) "vipo alire to p-aryfcFcixrktvr111e-a-d.compatmCr.1jU^nauai^ ^ ^.-..-j f rrri^f may bs estimated by the analysis of air samples taken from representative parts of the' jf'i C * 4.*,^43K4.V j Obviously the use of this method involves certain assumptions; - (1) that the inhalation of , lead compounds constitutes the only important source of lead absorption on the part of the plant population; (2) that the lead part-i-cl-os^ found in air samples may be breathed in and re tained within the lung to a more or less uniform extent by the workmen in the area. Various technical procedures have been em ployed to increase the practical reliability of this method. Fre quent sampling over prolonged periods tends to reduce sampling er rors. The manner of preparing samples for analysis also t ends to exclude particles of lead compounds which because of their size are incapable of inhalation or of retention in the lung. Moreover tre greater practical significance of inhaled lead in comparison with soseooo .ax ingested lead has been well demonstrated byexperience and experi ment, a n d is now almost universally recognized. On the other hand, lead poisoning can and does occur through ingestion of lead com pounds, and unless precautionary measures are effectively t aken ingestion c an occur to such an extent as to void conclusions ar rived at by the analysis of air samples. With certain reservations required by the preceding con siderations, it may be said that if the concentration of respirable lead compounds in the atmosphere of plant work-rooms is generally kept below the level of 1.5 mg. Pb per 10 cu.m, of air, and^permitted to exceed such a level for only fleeting periods of time, cases of plumbism in the plant population will rarely,if ever,occur. (5) It has been shown that the magnitude of the lead exposure in a plant can be determined by.the study of the lead content of the excreta of the employees. Briefly statea, the lead content of a single evacuation of the feces of a workman serves to show the magnitude of his lead exposure for the period of inwa twenty-four to seventy-two hours previous to the collection of the sample. A large proportion of all inhaled lead is collected in the nose and pharynx and eventually reaches the alimentary tract, through which it passes in large measure un&bsorbed. It becomes,- thereby, an indicator of a m a n 's gross lead intake for the period represented by the feces accumulated in the lower bowel - a period which experi ence has shown to be approximately twenty-four hours^ The concentra- -5- tion of lead in a large sample of urine (collected over a period of forty-eight or seventy-two hours) varies with the rate of daily lead absorption and with the lead content of the body. Therefore, it discloses the general magnitude of the lead absorption over a considerable period of time. More recently, it has been found that analyses of the blood of exposed'persons will also reveal the general magnitude of . Z\ a-sLcs their lead absorption ana exposure. The/blood, w l X F i " r ^ e - p o _ u-r' sva^.r.J 4i#^ & 3=&d .c oncea-t-ra-i-l o n d o %g-n.Qt,.atf4^g^-ci-ia*uy> <?n - ate*. 'g,-, proper- la!on i-.eiy.-'Lsaaa^ as the 'urine, in response to lead absorption, and therefore, blood analyses are not so sensitive a means of detecting lead exposure. Such analyses, however, are useful in the stu d y of /U.. . industrial workmen for a number of practical reasons which vssigsa: not be discussed here. ' The correlation of analytical data of the above types with 00:5507 the observed conditions in industrial plants, and with the clinical findings in plant emplpyees, has established a basis for the differen tiation of safe from dangerous occupational lead exposure in practi cal terms. Attention should be called here to the detailed data of . 3 ,, our various studies of the lead excretion of normal persons nr w o l l - -6- clearly that above a certain level of lead exposure, a s expressed by rateJof lead excretion of representative groups cf workmen, the occurrence of lead intoxication is progressively more fre- quent as the occupational exposure increases in They also show quite conclusively that 3 cases of lead intoxication etc U M occur below a certain level of lead intake and absorption. The precise poin t,(i f 1t-- b o a 1 pryrrrt^-of the--- e-ritic a! $ &. K Ji f' f si \ts&i i ** f v q j" n or ~h p r',-Pi^ n11 ^ nnri h?Y<ar>/iMVa ^ th e,,e term s, i-e-aert shajapJL^p-rt'e-gjjaad at present, but a range of values can be set up on the basis of present information with every assurance that they are substantially correct for all practical purposes. Reference to those ranges will be made subsequently. The Technique and cope of the Present Investirrat 1, A preliminary inspection of the plant - a brass foundry was made, on the basis of which a small group of .employees was se lected for study from what appeared to be the commonest ana. most hazardous occupations. Subjects with the longest recoins of con tinuous employment, and with the greatest expectation of continued /employment>were chosen, the fin/al choice having been made by the 8CSS-00 J3X ils detailed knowledge of the occupational and personal history of the employees. The large proportions of the 'workmen were employed in one large room, - i.e. the main part of the plant in which a // g operations .vere carried out. These opera- tions will not be described in detail. Suffice it to say that they were of the type that are common to such plants and that some of them involved little or no/* exposure to lead. ' `his fact, however, is quite unimportant, in relation to the actual lead exposure, since the handling of molten metal of high lead content in one part of this room resulted in the contamination of the air in all oarts of the room. a . considerable degree of control of the fumes was ac complished by means of general and locally a ppliod ventilation. However, on account of the mechanical difficulties of fume removal from rapidly moving pots or ladles, the chief effect of the venti lation was to dilute the lead fumes extensively but not uniformly in the large room. As a consequence of this condition, it was not possible to differentiate degrees of severity of exposure with any assurance of accuracy. hirtner discussion of this problem will 8- develop later. It is mentioned here only to snow that the general lea exposure of the plant had to be studied not in relation to specific AA *ttv ^ occupations, b u t I n roilutitw to the volume of lead vapors and fumes,and their dissemination through the plant. A large amount of molten metal, much of it of high lead 'q content was being handled at the time of the visit to the plant. ? ~Zt \glS' were seasonal variations in the productivity of the plant * At< Such variations i^a^a-liing in considerable change in the quantity of 44't4*f^. lead vapors and fumes. There were also^variations in the propor tion of high lead bearings in the plant production. These factors could be expected to influence greatly the severity of the lead expo sure of the men working in the large room of the founary. I n addi- t j_on is** ^ v entilation)during the warm month's of the yeaxnwhen doors and windows could be opened. This factor could hardly be expected to operate with strict uniformity in reducing the lead exposure, in that some persons would be benefitted more than others. The overall effect, however, would be to dilute the lead concentration in the air of the plant. No attempt has been made In this report to assemble the data on production as a whole or with 0005510 - 9- to correlate these data, If available, with the results obtained. Moreover, the information with respect to the number of persons em ployed in the different parts of the plant has not been obtained for this repox't. finally, there are no d a t a on the seasonal changes '{Sc.// in ventilation. .Krrenrlodge as to the influence of these changes upon *' the mean concentration of lead in the air of the plant, 'would hzji&J As*U*a*..'v'i`IrtAiM* -~~C`i X - tP great pracxnLdeJ-- impjaud^axuie */</ , />Y~" A 7% z.t w u W a* A*~&**&*v- n? ^ ` ^ ,/,TT i-T <h.. Twenty employees were selected fox* study over a period af C*-J {jtltMvi Ia &jJJAlliuJtitP jut"t /*-<- I time^ Samples of feces ana urine were obtained in December of 19 36 , and in May and September of 1937 by methods which experience had shown to be satisfactory^Tr<o:a-1,h<-T*irgi^wQ^.i.e*.Q.f a-vcrjdaaie-e^-- acrtHa-cL-iUL-- (^ nte%Hiwrrra-4Ti. Blood films from these men were studied at regular intervals for the determination of the numbers of stipolia M -J* v OLti ^ A^^-v C-vC^ erythrocytes#? ^Uvengugnmpl e te.ohoiJ^;^J.,~^xxuaipaat4an^^n^rn^ # *%"<SU|^ &&*Jj***< hhe ifiu^p epYPr>g . A fi..... "`"rS' --/>) ~ : .. ^^^'Vvcvu, Liei n^a . 1*4, th j p a A a xuuaoiaA.ha4""*^^ ; ^ AMM/xtJi rS-t*^v..-,D ~ta, M4i ew5#ttftCs Anuu^-Jt & J ^C/ ^plexe microscopic -.bln.od^xamixiat.io. r t * S-AAUCO 'juXJt^A^ Ua// carr.iAd - o u W "* "n il.-gfp^te^e *"'gt y y e r g "^ r>iriivRg,5 ,were * f?ns5th--tLs to '^who'le.. The composition of the group of selected workmen with respect KF 000551 - XU - to age is shown in Table 1. It may be seen that a wide range is 5,(f covered, although the total number of the group e-s net z&Llmv ade quate representation of various age groups, i'or tnis reason the clinical effects of lead absorption upon the occurrence and develop ment of the degenerative diseases of the middle and later years of life, as weal as upon disabilities in the eax'lier years coula not be studied here. Previous observations have shown that age does not influence lead excretion materially, and, therefore, there Is / no reason to s-u-spb-e-t tnat the analytical data are 11 ; ] ~ valid as an indication of the over-all lead exposure of the gi*oup. T-'iis small group is not necessarily representative of the ti"6 distri but!cn of Athe workmen in the slant, but ss-r'iubws tnat no age group iv itnin the *. period between early adult life and early old age is lack xng in the plant population. Table 2 j in waich t he subjects are grouped according to the c\2 duration of their continuous exposure in tae plant, merely snows that the group has been w e l l selected in t h ^ r egard. it should be possible to determine whether or not time is an important factor in the lead exposure and absorption of such a group unless t h e r ^ h o u l d HE 000551 11 0f occupation, `'he effect of the latter is open to doubt for re sons pointed out above. Table 3 presents the facts with reference to .4? the type of employment represented in the selected g roup, giving also the duration of employment of the representatives of each Hri.utJ occupation. ihe rudders atecrrc are sufficient in number to be adequately representative of their group. -I will be a - 'rd.pppct' , ~1 un q In April of 1937 'jHKt following the winter period of maximum lead exposure^twenty two workmen were examined, son in the ~rou; was subjected to detailed questioning. Lvery ef fort was made to .lain his confidence and to induce him to talk freely about any ailment, illness, or injury wnich, in his m i n d , might have been due to occupational conditions in the past, or might arise from present conditions. Leading questions were avoided at first so as not to color the employee's response, but were employed subsequently with respect to specific symptoms. in- ^ t -* formation as to gervgral plfaw t condit ior:s/'Tbheatti tuae of other tjCii UrrJeJ, _1 workmen toward the potential hazards o6f theh- e' - ,^'tne extent of CiOh^ the labor turnover because of1^>aisssaattiissifaaccctiionixiijs^i:stS the occurrence of illness amgng other fmtjhl y n `" "h i was sought dis- H 00:55 &0**\*^r from a number of the older employees, Tnese men appeared to respond with complete frankness, and gave useful statements of fact and opinion. a cai'eful physical examination was carried out, in the course of which-a special effort was made to observe and record any symptoms and signs of lead absorption. Thus; special care was given to the examination of the gums, and to nervous ana neuro muscular reactions, a complete microscopic examination of the blood of each .man was carried out at the time. and. a fresh sample of urine was examined for reaction, the presence or absence of albumin and sugar, and for sediments. The clinical data were studied carefully, both as to individual persons and for tne group as a whole, and in sc far as ! it was useful or feasible to do so, they were examined by stauisuical means. 0005515 The Results of the -investigation The initial inspection of the plant indicated that the , opportunities for exposure to lead fumes and vapors were wide spread. It was difficult, however, tc make an even reasonably intelligent estimate of the severity of this exposure. Lead fumes, manifestly, were given off from the pots while in transit to the molds, and during the pouring, but there -was so much smoke in the main foundry room that one could not judge the decree of contamina tion of the air with metal fumes. The ventilation, large in volume, was designed, so far as possible, to remove the fumes from furnaces W T a .-./a<>.cc-nm JJ' and pots, but it was e-bv-iou-s l y , and for reasons dual were quite apparent. Lead-bearing dusts were also distributed into the air at various points, and even the metal-washing process, wrich could have been free of dust^was not entirely so, by reason of some `-f laxity nn t-h-p pi'rt nf 'L-tvi ^ y ah . housekeeping, in foundries, is a difficult problem, a t best. One felt tnat while this source of lead exposure had not been ignored, it was not re- 'vnxU a# ceiving the continual attention that -wac e^a^ a.rl*cu*fijmflt; A* There was little or no separation of the functional areas of the plant on the basis of the lead exposures that characterized specific occupations. This, in sone respects, at least, was unfor tunate, since certain occupations could have been freed of lead ex posure through isolation. On the other hand the frank dependence /Jut***a upon ventilation as as means of controlling the lead hazard through out the plant, indicated the acceptance of responsibility by the management, and if the ventilation were t q -be-- found adequate, this C-tA' `if s&Cu*//' /44. hygienic problem could be regarded as solved to a large extent^. .Ge-q ) 'Li.t! ;vnr '//;;/ . 0-'Z>-_ >**t}i** *f Lo c44**?i t a .in a d d it i- cnfrl;' -ooii'in en t -s--orr^t l^ fS.p o iTit^ ^ l ^ ^ a p p e a r 1' amt?tlr!^trh ^-r^eom ae4>-'- ***}}'' A ' yr~ / h / p t\ Z **t**tt4,r*Qf i **w . jhc*._ t. h ); *** -hSt** -C` .'Tf" J '?/ .- ~' ; / The examination of the small group of workmen revealed several faces of importance. There was suggestive evidence, in re sponse to questioningjof the existence of dangerous lead exposure. The conditions In the plant, as revealed by the men, had been much worse with respect to the removal of fumes, prior to she installa tion of the present ventilating equipment, curing that period "brass chills" had not been uncommon among the workmen. Those nad been eliminated entirely, apparently, by the improved ventilation. On the other hand, there had been cases of lead ii.tox.icat.ion I:, bofch ..v^r .% I s-* y K k 0005517 > as judged by t he de scription of apparently characteristic episodes by certain workmen. Apparently, during the peri on in w.iich the bearings were generally ' low in lead content, the lead exposure was not very serious. Later, however, with the increased lead content of the bearings, the lead exposure from this source increased to such a degree as to be hazar- dons, in the dace of greatly Increased v e n t i l a t i o n fhere was no noteworthy anxiety among the nen concerning their health, and the reeling Was general, that the conditions In" the plant were not unduly hazardous. A number- oh the nen r-*f L'J that they had experienced -- i_paim e n t In health A s a consequence of their work. ,'d /?. r*'**afy-rs'\jore somewhat concerned about thex a,tst J s*&! *>(that gave rise to common colas. ihe physical signs of lead absorption, while considerably less prominent than one vv&s led to expect from observation and ques tioning, were sufficiently numerous to justify the conclusion that the lead exposure was not being held within entirely safe limits. fable 4. summarizes the purely clinical evidences of sign!- ficant lead absorption. h;3nme of the items 1 open to question, J-Y i 1 ly ^ i 'f-yTrffN^g the smallness of the group, `he frequencp'of ft :: occurrence of constipation, vague abdominal discomfort, and polyuria, as complaints, belong in this category, as well as such physical signs as' exaggerated reflexes and tremors. The occurrence of six persons with/jlead line# however, among twenty two men is highly significant in that . in general, does not appear except under condi' tions of fairly severe exposure. The degree of extensor weakness of the forearm is somewhat difficult to estimate, but two cases 'with a degree of weakness that seemed definite t o .the examiner, cannot be. ife-^o.beas3sxkhyihH0r!naTTtl'e*rS'TM,wn*e''-'re-^aa-.le.d,~-bbyy^o-i&ird:'d:ir!ary 'cTin i 1, a n s ] j o, i s t re^kj-reT- t-he-ae^-at'-a'-'were--rTO'fc---1abu----- ttfry - i ^ . he results of the leucocyte counts are shown on T a b l e*$. Only two of rti-nfl*,c were in the ranges commonly regarded as abnormal, and these were not of any specific significance. C5 10 i-O oC,.- o Table $ shows that most of the men examined had some degree of anemia, and in six instances this could be classified as fairly V severe. The significance of this situation, as to general health, L>ilkt XOkCi absorption nay well be a factor 1s offered by the relalively low incidence of definitely abnormal heno glob in concent rat ion in the blood. H E 0005520 ^ A* ',u*/ttt./ *u4~^.(' '-+.(cju*~r co UjUv'"yu*-- *y 1`he group here under study yielded a mean value.of almost ten tit.es the normal in December, with a gruuual falling off to such an extent that in September a number of the workmen showed no stip pling and the mean value for the group appro ache d/the normal level. -> it is of considerable practical importance to determine whether this change in the blooey-picture was associated with an ac '/ / tual and mere or less corresponding decrease in the lead exposure in the plant. Previous observations have shown that the mean ox* average levels of stippling of sufficiently large groups of perseon: vary with the severity of the lead exposure of the group, however, individual - w r l ..t within Aiwb grou;S and certain unknown V-. 4 /i/<:fi.I , *S factors ^''perhaps seasonal ox* nutritional^' induce aIgn if learnt fluctua tions. If so small a group as this i/ ,' Or o vp C: U T2 t o su ch striking degree, despite the extensive variations due to other factors, a very useful ana relatively si.-.pie method of re- co "nizinrr increases and decreases in the lean exposure ox a paant a: a whole would seem to be available. On this account the comparison of these observations with the data on 'mid"" c * * o t i g n o f ifTO is of great interest. The analytical findings are grouped in Tables 12, lp, and li;.. It is apparent that the lead in the Teces of these men is ab normal as comparec with, the mean normal levels of approximately mg. Pb per sample, and 0.0^*mb. b per gram of ash ir; the feces. On the whole, however, these results are not as high as might be expec ted in view of the'apparent severity of the occupational lead expo sure as indicated by the clinical observations. The reasons for this would, seem to be that the most hazardous exposure in this plant was to the vapors and fumes of lean, which in their finely divided form would not be entrapped to any large extent in the upper respira tory tract. dnj_y a small proportion of such lead would fine its way into the alimentary t r a c t . ^ ^ j r K-- There is, moreover, little evidence of change in the lead exposure and absorption, over the period of s tudy^sas evidenced by K J? 0005522 change in the fecal lead content. There is some slight diminution m the.lead concentration h A afit expresses in m i . n g r a i u .*. -he o.f` <,.& per gram of JSS3BS. ash, out -- 1-s--vn>t-- entirely 0 efivinoi.^. an-- '4, SiA Xas* 4^ X* 1Kt>vJ J-A'-S t Ql corny The mean urinary load concentration of the group shows a be tween December and March is not very striking, and, indeed, from a statistical viewpoint it could be a matter of pure chance. The same is true as between the March and September results. 'The change from December to September, on the other hand, is a significant one, statistically, and even more so physiologically, since the decrease in lead concentration.at such a time is opposed to the normal sea sonal increase, (based on decreased water output in the urine during warm weather). We may^ c o nclude^^aiZ^ therefore, that the lead ab sorption of the men decreased definitely i n c e p t e m a e r as compared ~~$u /**.<'* withj^Decem b e r . Granting the correctness of this conclusion, it seems probable that the trend throughout the period of study was in that direction, a s suggested by the individual steps, themselves insigni ficant. The absence of a corresponding trend in the results JqcAa J is not remarkable in view of the sources of leaa^ fauna uliwialir, and considering the diff icult y./of obtaining samples that bear a demonstrable relationship to alimentary function. In contrast, the 7Y F 0005523 factors which influence the urinary excretion of lead are few in number and fairly well defined as to their effects. The renal lead excretion, therefore,' is a~ sensitive, means of measuring lead absorp . ch 00055 1.nd rea-t -ii*>n~ in the food and n r e s p i r e d air of an individual for the somewhat indefinite period of time re presented by the sample." C The decrease in the lead absorption of the group as re vealed by the urinary lead analyses is of two-fold practical impor tance in this study,-- first, because it is associated with a corres ponding or even more striking decrease in the frequency of occurrence of stippling, among the men, ana second, because the occupational lea^ exposure as indicated by lead encretion was definitely hazardous in a Id cember approaching safe limits in September, gbit is apparent tiiat the frequency of occurrence of stippling in the group is a clear inuicaticn of tne relative severity of the exposure. Inis fact snoul be taken into account in considering the various procedures available for checking the lean exposure of the plant. at should not be for gotten, however, that the data of this study do net. make a clear distinction between dangerous and safe conditions of exposure in term of stippling, `they suggest that when the mean value of the stippling of the group of workmen approaches the value iri*dit>ata for uecember in Table 11, the conditions of exposure are unsafe and are likely to indicate that when, as in this instance, the lead exposure is largely of one type, the upper limit of safety, as expressed in terms of the mean frequency of stippling of a fairly large group of workmen^approximates 10 per fifty fields, with only occasional results in excess of 50 Per fifty fields. (These values are based upon a precise and uniform technique in preparing, staining and examining blood films They would be different if the methods were to be modified or carried out less uniformly.) The severity of the lead exposure ^as snown by the urinary lead concentration, can be compared with that observed in other industriayplants in which corresponding observations have been made. In our experience cases of lead poisoning either do not occur at all, or are of the mildest type, if the mean urinary lead concentra tion of representative groups of workmen does not exceed 0.10, mg. per liter. Cases are infrequent and comparatively mild^if the mean value is 0 . 15 mg. per liter or less, tfc* .jjbove tnis level severe and dis no a abling leau intoxication can occui', and does so with increasing fre quency Ti pi nl pmjrrrfar^^TTTr. The significance of the observations on this plant isC^therefore ^-gflyfrgQgqa and it is a matter of particu lar importane^ that the severe conditions of exposure noted in 00055 December aid not continue throughout the yeux-*. This factor, in all probability, w as responsible for the non-occurrence of plunbism MUr. V:-'n: ' the plunf during the perioa of study. nevertheless, the results demonstrate that the exposure was not so controlled at any time a-''u< Li,.u during these observutions as to b e ease. 1 ne s of control, therefore, should be strengthened and improved, and the factors v/nich caused the decrease tna t was rioted should be aeter- mined and augmented, if tin-t is feasible. In any case, ventilation which proba&Ly ..the fa-e-frer* - r o o should be >rcvea, either in the 1er of its application, or in cu-ntity An attempt wcu-.h, ....thde to. relate the level of trie lead ex crction of individual worn :en to their occuoation. a otu:.- jo was entirely fruitless, ano no tabulation of tne ^ no such r elationship coul~ a>e esCasiisusd ne lasion nas oeen h-ven. .n iaua oea previously, this was to so expected from the nature of one plant n.s k M 'the lack of any sejreg A .. r? p`h` -py-'i-v''' i n h" ';i * Table lp suov-s six results of the search for a correlation between the severity of the lead exposure, as indicated, by the urinary lead excretion of individuals in the group,and (1 ) the dura tion of the exposure, () blood pressure, (J) hemoglobin content of the blood, and (ij.) numbers of erythrocytes In the blood, and (?) the numbers of stippled erythrocytes in tne bloou. it should bo noted that there are lour entries unuer each pair of rubrics, and that those ure mutually exclusive, constituting thereby, a so-calis four-fold table. Correlation in any two items, whether positive or negative would be shown by asymmetry in the four-fold table, wnerea substantially e:;ual numbers in tne four corners of the L*aoxe s that there is no relationship between the itemj. The fact t nuu n e correlation appe.rs in anv instance nav be due to the mull sia tne -rou ;rc Lui dossibi f th a m a i i; o result is a u o`or c. .i. poinos,copec ;.)C! stippling. x'he frequency of stippling of ne ery lw.rocytes in tn group as a whole vac found to vary at diff rent times m ae cora ce with the level of urinary lead excretion. respite tnis fact.she is no correlation betunen h u inuiviun.C f :___ 1 ; . n un. lend H E 0005527 concentration and t he corresponding data on s tippling. ~re>. r.ne urinary lead excretion of individuals is known to be an adequate criterion of the lead absorption of the individual, t h e _lack of correlation can be due only to the lack of any precise relationship between lead absorption ana the extent of stippling in the individus lead absorption is uniform in type, but is highly variable in degree. The practical importance of this is obvious in that an absolute stan dard for a potentially dangerous level of stippling can hardly be set, except on tin basis of a: figure low enough to cover practically all cases. V 0>>priiri-thra-a^iraynmy 1p'>ri - re suit.-i-H-cliaii'ue "liT~'tlic-^imSeln^a4da%dqool^rd-^^Ylhrr&c^p-^-s-4rn-^^e^-e^l.^. pheral rrrl ffiti^n ^ but to..--vaujj^i-n^-de^re-e--s. g^In considering the individual case and not the absolute number ^ef- t,?gpl od *> Lhr uoy toe found. In general, experience has shown that the person who tends to have large numbers of stippled erythrocytes when there is little or no lead exposure Is subject to relatively large increases in stippling in response to lead exposure. . The lack of correlation between the urinary lead concentra- tlon and the length of continuous employment in the plant l _, ***"" n prvil ij 11IT'hj1 to the variability of the lead exposure and absorption from season to season, from d a y to day, and from place to place in the plant. The other items indicated in Table 15 need not be commented on at this time, since any attempts to explain them would be specula tive: in character. Summary and hecomnendations The discussion of the results which has accompanied the presentation of the data needs little amplification, however, it may be useful to summarize the salient facts as a basis for recom mendations. - The lead exposure associated with the operation of this plant during the period of these observations was of an order of magnitude that must be regarded as hazardous and capable of pr o ducing lead intoxication. This conclusion is justified both by cli nical findings on the men and by the results of analyses of their excreta. The lead exposure, while variable, was sufficiently general in tjie plant that all the employees that were examined, regardless of the nature of their worl^ were subjected to hazardous exposure with approximately equal frequency, so far as could be judged from the observations. The general lead exposure in the plant decreased in March as compared with December, and again in September as compared Iliarcli. inis aeci'o&se t m attributed tc. the increased -all ventilation Inciaent to changing weather conditions. It 1 ^'important to know vmether or not tnis is the correct explanation, for thi-'reason the plant records^ for this entire period^ on liaplo xmen t , to 11*1 p rodu ctr o n , ana p ^opos1 xoi-d,1 prod no tak^xi o1 b ecar ~ --. :;.; .. ? 1 Of high leaa content shoulu b e scrutinised carefully. It would be well also to look into the local weather reports of this period, of 1937-33 and to consider them in relations so the probaole nur.ber ina location of open windows ana doors. If ventilation aoove can pro duce a chaiige of tlie ma gnitude indicated by th e results of O.a!b Uti*" vey, one means of improving conditions is obviously available. KE 0005530 In general,the precautions taken against the dissemina tion of dusts is a number of procedures were sc: .ewnat inade quate. The men, themselves, were net sufficiently careful and t:>ere was not such supervision in matters of safety as would be desired. It is believed that there was a signifi cant amount of unnecessary exposure on this account. . The mean frequency of stippling of the erythrocytes of the group of workmen as a whole decreased sharply ana . significantly, during the period of the study, as the lead exposure of the group d ecreased. This fact demonstrates the usefulness .of observations on stippling when ail of the results obtained in a given period are grouped ana compared with corresponding sets of observations. wn the other hand, there was no correlation between the level of lea.: absorption of the individuals in the group ana the number of stippled erythrocytes founu in their blood at the same ti m e . Considerable caution is required, therefore, in the interpretation of counts of stippled erythrocytes in individuals. Comparison must be maae with previous results on the same person, in oraer to a veil, the important factor of large individual variation. Certain recommendations naturally follow from, the facts stated in the foregoing paragraphs. Others arise out of more general considerations. ome are offered in the full knowledge fcnut the neat: of carrying tnem out is not immediately at hano. All of them are believed to be worthy of careful consideration to the end that practicable ana servicable steps may be taken to eliminate the lead hazards in this plant. There are two general metnous of approach to the oroblem of eliminating these hazards. The one depends upon xe sso o o j ?/V the application of generalventilaiion to such an extent that the lead content of the air breathed by the woidcmen is r educed and main tained below the danger point. The other is concerned with the recognition of the specific points of origin of the hazards and with their elimination at their source. The latter is the better method if it is practicable. It seems probable that seme combination of the two will be required. Obviously, it will be necessary to determine the degree of success of any iterupts w h i c h are made to el Inina te lead exoosure. Several means of doing t .is have been referred to in this report. It is strongly recommended that some study of the ventilating equipment be nude with special reference to the removal of fumes at their point of origin. The amount of moveorrra-n of a ir necessary to do t is ]c- v:%'.:u,rc*n ec z:u s- *u U X*GOg.i r o d to dilute 4- g e n e r a l a tir.o sphere o r adequ hee aa tt iinn cc Oolla weather will be onrtlv solves b~r t,, 1 s m ean s h e r e a s i t vvil oe greatly Increaseu by a general in ci^e C 3 C ii nn ventti11lataiG-on* The difficulty of accomplisuing t h i s pur pose arise s f r, the mobile nature of m e sources o f fume. It IVoui se that the logical way of aealing v;it trais, if feasible, would be to localize the handling of molten metal, applying the ventilation at this point, aria to mo v a tne tc molten s cannot be done, even in part, under present conditions of urgency, KJT 0005532 it would be feasible ir. all probability to i .'.prove the aCTt sutl? H local ventilat ion the "pouring operations. further improvements in the ventilation might well consist in attempts to a v o i d dead air pockets and points of inadequate ventilt.ion Adequate balancing of' input of air at proper points against exhaust ventilation would < f. be desirable. Isolation of certain areas of the^lant in which non-hazar dous operation s are carried out is probably desirable and may come to be entirely necessary. This could be accomplished in large mea sure by localizing the more hazardous areas and applying ventilation to them, while at the same time maintinaang good housekeeping and in telligent avoidance of unnecessary exposure among the men in the relatively unexposed areas. There is no need for the molders, for example, to be exposed to lead fumes or to significant quantities of Adust. Af the over-all lead exposure, were insignificant this would be of little importance. Under present conditions it is a highly important ?'h:hr, fo-- if tier:; 'r- re tier. i.m-x- posed persons, there is no possibility of transferring men out of dangerous areas into safe ones^for either short or long periods. Hereover, the medical care and supervision required b y the men who need not be exposed, could be greatly reduced, thereby.freeing time CO and facilities for the men whose exposure is difficult to control. Kff 000553 Supervision of all the operations in the plant from the point of view of s afety is definitely needed. It is conceivable that th0can be done by operating supervisors, if the latter are sufficiently Interested or capable of b o i o w t ly""4n $ &&&$wrd in the maintenance of safety coincident with or in spite of the re quirements of production s chedules. 5Ti. *.-- * >$ Retailed supervision of the men is necessary to prevent acts of carelessness on their part, to maintain cleanliness in housekeeping and to see that cleaning is carried out by methods that do not disseminate dust. Training in the minutiae of procedures is necessary, and education in tho sources and significance of lead exposure is an absolute requirement in such supervision. lerhap a trained safety engineer, properly fitted into "A the hygienic and medical organization of the plant would be required, but in any case the person or persons responsible for hygienic natters must be completely versed in all the activities of the plant and must be in continuous touch with any a n d all changes in production and with all operations which influence lead exposure in any manner. The removal of fumes from the plant involves their distri bution into the outside atmosphere. The extent to whi c h these fumes en 10 m o return into the building, or settle in the immediate vicinity of the CD CD plant is of some consequence. The deposition of lead compounds on sur VU rounding surfaces from which they may be swept into the plant by winds and other air currents may c reate an additional factor of exposure in the plant. The re-entry of fumes into the plant through open wine or doors, under suitable conditions of wind ana weather may also be a factor. Furthermore, the lead exposure of persons who live in the vicinity of the plant merits some consiaeration especially in the / case of children who may swallow appre/icdble quantities of lead de rived from dust laden surfaces with which their hands are in fre quent and intimate contact. (Children sometir.es lick or chew window sills and similar surfaces, and a number of cases of lead poisoning <-L. in children have developed in this manner, chiefly of cwswrr,1'rom swallowing dislodged paint.) Considering the finely divided charac ter of the fumes, it is unlikely that there is a n y d anger of this type but information on this point would serve to establish facts which may turn out to be very useful. If there is actual from this source either in the plant or in the neighborhood, adequate means of handling the problem arc. aval375*03^ . It Is recommended that observations be carried out resn larly whereby the severity of the lead exposure can be followed. The clinical data needed to maintain an awareness of the condition of the men must be obtained. In any period in which there is reason to believe that the exposure is increasing or has been increased above HE 0005535 the usual level, the men should be examined more frequently and more critically. If dependence is to be put on the results of the exami nation of blood films** for the recognition of changes in lead exposure q -. among groups of persons, such films should be made and examined at intervals which are frequent enough to reveal the trends promptly. if they are employed to detect changes in the status of an individual work man, they should be repeated frequently whenever any significant in crease occurs in a man, so as to establish the trend in his case as promptly as possible. It would, be useful to be able to check the lead excretion of persons suspected of having prodromal symptoms of lead intoxication or of persons thought to be unduly exposed in their work. It is not 0005536 feasible to analyse samples of blood or urine in any laboratory which is situated within or near a plant in which lead compounds are han dled, unless the lead compounds can be excluded from the laboratory quantitatively. This roecrtss exceedingly efficient filtration of the t*.rhxii ' air of the laboratory, and the exclusion of dusts^on the person or clothing of individuals. On the whole the difficulty of accomplishing these results renders impractical the establishment of an analytical rying out such analyses elsewhere might well be provided, and it would be especially advantageous if a group of industries were to sponsor a local laboratory so equipped and manned as to provide un questionably accurate results. The advantages to the plant physi- clans in having an source of such information would be great indeed. It is not to be supposed that such a laboratory will prevent lead poisoning if the conditions of exposure are hazardous. The only remedy for that condition is the elimination of eXp O SU.170 y and if the latter can be done, expenditures fox'- analytical facilitie are probably unjustified. It is possible*, however, to recognize dangerous lead exposure in advance of its worst effects, and to differentiate prodromal plumbism from a variety of other illnesses. If lead hazards among workmen are unavoidalbe for a time for any one of several reasons, which may be operative, it is highly advisable to have available the mostprecise means for the early diagnosis of lead poisoning. 000553-7