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9099IM Inland Stasi Company CO 30 CO "O o o Vu company of Dr. K m n m and various members of the technical and ' production staff of the plant provided a fairly ooiaprtensive . grasp of the prohibas under consideration* Dotal led study of . . the data obtained by the analysis o f the air of workrooms and lawhere over the period of the past year has served to fill out the picture further* For the purpose of making the present interpretation of the situation these analytical results have been accepted at their face value* It m e t be pointed out, hoverr, that since these are the only cuantitativo data available* and since conclusions of far-reaching importance must b based upon then, it is neither vis nor safe to accept their accuracy without proof. For this reason I shall eabae- ' .' quently suggest the means of testing their validity* " ; Certain, donerai Oonatderatlona " The Significance of the Analysis of M r for Lead Content ' The -estimation of the- significance of occupa- tlonal load exposure by dotorhining the load content of the air . is b & s M on the' generally accepted principle that load poisoning ., ,/; in industry occurs largely:'-as the result of the inhalation of:. .' ' :,. dangerous quantities of particulate load which are present' in . , the atmosphere o f workrooms* It has boon -observed'.'that if the . concentration of lead particles in the atmosphere does not exceed certain levels* cases of poisoning either do not occur or are so \ mild as to be of little or nor consequence. By roseo of variations KE 0013381 . to&per&turoa lenir of tha working day.*, and steadiness of onployment* th threshold value for dangerous lead exposure have borni set at different level. by different, hygienic workera* At present it can bo said -that the general concensus of opinion, as vli at contain official, and seal-official agencies,favor a ptmiaalblo concentration between 1 milligram and 2 . milligram of finely particulate lead per 10 cubic metara of air Ky exporienee .has indicated, that the higher figure* l.o. 3 2 mg/10 M - 8 a safe one* regardless of the type and subdivision of the lead compound* provided general hygienic conditiona are maintained In a satisfactory atat in Induetrial pianta* and provided medical supervision serves to eliminate the. definitely unfit worker frost the plant population. ' gl - 4^--.^.iyg.l.a ap..a . Mods or Sstlgfotlft& the Ol.fmifioanoe of head axpocure. fb provisional character of the statement .above suggests that air analyse as the solo method of evaluating occupational load leave something to b desired. Such* unfortunately, is-the case. She difficili ties of sampling the - air of workroom arc oensMerable* in that variability and . periodicity in the operations.*' change in, plant equipment and ventilation* and Shifting weather conditions introduce many factors which must be checked? the methods of analysis of ample m o t b of the utmost, precision*'and such precision is not easily obtained around industrial plants with contaminated atmosphere* 'The rate of pulmonary ventilation Varie from 5. liters per minute to 25 liters per minut* i,e* from 0 , 4 cubic' metore to 12 cubic ... motors per g hour working day# dependent upon tine degree of exertion required by the occupation, % d 'the additional variable that ' relatively coarse particles never roach the lung tissue but are :trapped in t he upper- respiratory.tract and are subsequently swallowed (and partly absorbed, in the alimentary tract), while ' .:-. finely divided particles may be so. small as to behave like a gas and so be breathed m t Ih large part after once having been 'inhaled, Thus the problem can bo seen to become a complex one, with not wholly predictable results. In addition to these considerations, which can be covered by introducing a largo factor of safety into the level accepted m permissible (as soma ,. :have don by urging the adoption of the concentration of X mg/l -VL9 /.as the 'safe level.}, there is the problem of organic disease among;-. . ;.the workmen as- a factor in. susceptibility-tc. lead-'exposure, Xt in' . 8welX known that general vascular disease* 'sad especially liver '. ' disease are Important factors I n susceptibility to- lead poisoning, .; .while certain other types of illness are so difficult to differen tiate clinically from the effects of lead absorption as to provide oases which must be handled, a though they were lead poisoning* if once- th .possibility-of load intcxioatlon-be recognised or believed to be present, 'There is always the problem of deciding which condition ia responsible for illness or disability, and additional measure of hygienic control' m a t be exorcised, not only to avoid ha sardn lead exposure, but to obtain more or ' leas continual proof that such exposure is being currently avoided* This can bo don in the opinion of the writer only by mean of regular -and adequate medical supervision of workman* ' Such supervision m a t (1) exclude the physically unfit, Ic. those to idiom the lead exposure of the occupation. will probably be hasardotm (2) m h e such observation on the exposed a to determine whether or not they are actually absorbing significant quantities of load; (3) maintain such record a will prove the . adequacy of the supervision! (%) check carefully every case of ' illness so as to exclude lead as a factor when it la not, by arriving at an acceptable diagnosis of the actual nature of the . illness* !?0t to go Into the details of procedure. to accomplish, the above purposes, suffice it to say here that preemployaoat and periodio physical examinations of & fairly comprehensive type are required, at that blood examinations of a standard type must be made and recorded* I n addition, the urinary and fecal lead excretion of at least, a t m representative workmen should be determined at intervals, and,In caaes Simulating piunbtes* study of the lead excretion should he mad- promptly 2he above recomend blona are predicated, of course, upon the existence of hazardous lead exposure* or upon the existonce of lead exposure which ha not been proved to be Plant Conditions as Observed and Otherwise Demonstrated. On the basis of the observations made, the lead hasarda of the plant procedures sees to range themselves In order of decreasing importance as follows; (l) lead exposure during the pouring and cooling of lead heats: (2 ) lead exposure at the rolling mills, which apparently la at its worst at the blooming mill, and Is leas but probably significant at other mills: {5) welding and *scarflag* procedures are both associated with a dangerouft production of fume. (It is apparent that the hazards of this type of steel do not end at the site of manufacture but extend into the general field of use* In 00 far 03 welding- and/ or other hlgh-temper -ture processes are Involved.) Hi lead exposure associated with the pouring . of ingots is being handled to & very large extent by local '. ventilation and by the use of "hot tops'* and "hot topping" materials, The. analytical data Indicate, however, that the control Is not . * . wholly adequate, in -that dangerous concentrations of load can be found at times, althoughperhaps not for long, in the immediate vicinity of the ingots,, 'Unfortunately, there are no :data on the CO extent of the voli tallstation -'of.lead during the removal of the "hot tops" and molds and for some time, afterward. CO , o The exposure associated with the various rolling Ui procedures, and especially that at the blooming mill, is not under control, in my opinion, and is likely to give considerable diffi pouring the Ingots, which can readily be controlled by the im provement of present ventilating facilities, the other operations offer opportunities for exposure that will be difficult to control and that in my opinion will produce lead poisoning among workmen, and would in fact, have done so, except for the Irregularity and' Infrequency of th operations. It would be -surprising to me if : workmen who have had the longest and most frequent expo mire in the several types of occupation did not show'a distinct elevation in their load excretion,. Hecomendat Ions So far as plant operations are concerned, the writer believes that the lead exposure can be controlled and kept within safe limits, (AS to the significance of that beyond the confines of the plant* only time and investigation will cerve to determine* but the outcome should probably not be left to chance,) Control* within the plant* is an engineering problem, involving the removal of lead from the plant atmosphere to the extent re quired for safety, j la general it would be advisable to remove the lead by collecting it, rather than by merely diluting it. This may or m ay not be feasible in terms of production costa* but. it may well be found that the colleotlon of the lead fume would reclaim enough metal to pay in considerable part or in whole,, for the equipment required to collect it. HE 0013392 should be subjected to rigid Chech, so as to eliminate any question as to their precision, This can be done in a variety of ways, and In order to mates a start In that direction, it la suggested that a serisa of samples of known lead content be prepared In this laboratory and cent to the plant analyst for examination a n d 'report to us* On the basis of the results obtained further Chech may be made no needed* In recognition of the fact that whatever oapoourc has existed over the past year will have loft its record in the form of lead absorbed by exposed workmen, it is recommended that a group of workmen be examined aa to their lead oxerstIon./ -Thera are several ways by which this could be dona, each involving a somewhat different amount of work and cost, (1 ) One means of approach would be to select two or more men whoso-lead exposure has been maximal, sending them to mo in Cincinnati for -complete examination and de termination of the extent of their occupational lead absorption. It would require from Z to % days, dependent upon the initial analytical results, to obtain the desired information* the cost involved in such a study would be the traveling expohee, moderate hotel expense, a nominal examination fee of 10,00 per person to cover the cost of blood examinations etc., and the expense of analyses on the blood, the urine and the feces at $$,00 pier- analysis (the actual proportional cost of operation of our analytical, labora tory). ( 2 ) A second and better method involves the selection of a the examination to Include making duplicate blood smears* one set of which is sent to me for examination* one sot being studied at the plant laboratory by the present methods employed there. At least 10 employees (the moat severely exposed) should collect samples of their feces on the day following their exposure, and samples of their urine over a period sufficient to obtain at least 2 liters of the latter* (Containers for these samples, and instruc tions for their collection will bo provided by me, and in each case the samples must be collected at the homes of the employees rather than at the plant, A successful technique for this type of sampling has been developed in this laboratory.) This method of procedure would serve to determine the general order of magnitude of the actual exposure in the jobs carried out by the men so examined, The coat* here*, would be the express charges on the shipped con tainers and the samples* the expense of examining the blood smears (determined by the actual coat of a technician's time), and the . . expense of the analyses at #5 * 0 0 per analysis, (3) A third method- would be valuable as a measure of the comparative magnitude of the total lead exposure which, has occurred up to the present in the plant operations, It* .therefore, would be. an attempt to determine how much load absorption has taken place among the most severely exposed men. It would be less valuable than method $2 as a measure of the actual exposure associated with a typical day's work. It . consists in carrying out exactly the same procedures listed above present opportunities for exposure, studying them systematically ' ; and perhaps repeatedly by clinical and analytical methods both in relation to a. day of exposure and between exposures, so as to obtain comprehensive information m to the extent of their exposure and ' their absorption* Such data once collected could be used In com- parlson with subsequent observations to determine the extent of the hazard arising from changes in plant operations or from increases in production* and to check the adequacy of Improved measures of control. The cost of this typo of study would depend upon the means of doing the clinical work, i.e. whether done by plant physicians or by our staff, - the number of blood smears to be examined, and the nuraberof analyses to bo carried out at the rate indicated above. '. Obviously the us of any of the methods mentioned above, some combination of them* or a choice among them, may well depend upon a number of.factors, such as cost, convenience, or the- . .. i * urgency of obtaining information. Moreover, it would not be possible at this time to divert the efforts of the clinical or technical staff of this laboratory into the immediate accomplishment of such a pro- . O C' gras* as is contemplated iu Method 1 4 In view of the apparent , CO 'O significance of this hygienic- problem, however, and in view of our rTM< O keen professional interest In the significance of various types and, O magnitudes of occupational lead exposures, wo should fool constrained Ut X to carry out such early observations as might bo mutually agreed upon as essential. In this connection It would seem to be the better part of wisdom, pending careful check of the adequacy of the air analyses, In the present situation, almost any type of .' illness among the plant personnel'might be called lead poisoning. . by physicians. In that case, granting that such a diagnosis might . " be incorrect, proof of Its Incorrectness uould be required to absolve the industry from rceponslbility./For this- reason it is . believed that cases of Illness o f any type among the exposed per nonoel should be given complete and'careful clinical study, and , that analyses of blood and excreta should be carried out as an aid \ . to differential diagnosis and as proof of the significance or in significance of the load exposure._ Arrangement can bo made to carry out the analyses involved in this recommendation if it seems desirable that they be done in this laboratory. . : Signed! ' iicbert X."ICfthoeV h,D. . : Director, lettering Laboratory of Applied Physiology * College of Medicine University of Cincinnati ' n r 0013396