Document NDwpp0ykgRYYEg1odMy1pbjg

KSPORT OP AH INVESTIGATION OP OCCUPATIONAL LEAD BXPOSTOS From the Kettering Laboratory of Applied Physiology, University of Cincinnati, Cincinnati, Ohio. Particulate Lead Content of IXiat Deposits and Air in Garage of Consolidated Telagranh and Bleotrie.. Company, ork Cifcv purpose ojLJ&e.study The purpose of this study Is to determine the extent of the lead exposure hazard during a typical day in tho garage of the Consolidated Telegraph and Electric Subway Company, as represented by the lead contained in the air as dust or fusses which would be breathed by workmen in the garage. A special effort is made to determine the exposure in and near the stock room here some cases of lead poisoning have been reported. inscription of the building The garage is a single story building occupying a space approximately 200 ft. deep by 1$0 ft* wide. Light is admitted through windows at front and back and through fifteen skylights conveniently placed in the roof of the building, `inter ventilation Is practically limited to infiltration through cracks and walls and natural venting of warm air from the top of the room through small vent cracks which are always open in the skylights. At times when the paint shop is In operation a largo amount of air is exhausted through it by means of the exhaust fans In the paint spray hoods. The paint shop la against the north wall of the building and Is joined on the south side by tho stock room and on the west by the machine shop. These three rooms with the repair shop occupy a space 5 ft, wide by 110 ft. long -2 across the back of tbs building The remaining floor space is occupied by the garage in which trucks and other machinery are stored over night and by a locker ro o m 15 ft by 60 ft Two garage doors are at the front of the building* one feu* entrance and one for exit Inside the entrance door a gasoline pump is located at which all trucks are fueled as they enter the garage in the evening. Sampling, procedure two types of dust samples were taken* Scraplugs of settled dust wore collected from various places about the building which say bo expected to show sosse indication of the average lead content of atmospheric dusts over a considerable period of time previous to the sampling These samples were returned to the laboratory and analysed for percent lead and are given accordingly in the tabulated resulta (Appendix i>}* Samples of the dust in the air were obtained by means of electrostatic precipitation using the Mine Safety Appliance's electrostatic dust sampler* The dust was collected in aluminum tubes and after return to the laboratory were washed out in triple distilled water for analysis From the analysis the lead content of the air was calculated In milli grams per 10 cubic meters and Is given accordingly In the tabulated result* (Appendix A)* Locations of saw-pllng points were determined by a careful study of the building with a view toward locating, the possible sources of lead* Also spot samples wore taken all over tas building to determine the point of maximum load KF 0005470 - 3- concentration and thus to isolate the hazardous places* At two places a series of samples were taken over a period of several hours to determine the time variation of lead concen tration in the air* Simultaneously with operation of the electrostatic usfc sampler observations of concentration of carbon monoxide in the air were made and recorded for all samples. This was exneotod to give an indication of the extent of pollution of the garage air by exhaust gases from engines running in the garage* Kesuita Tabulated results from analysis of samples taken by the above procedure may be found appended to this report. By examination of those data certain significant facts are discovered and are listed as follows: 1 * At only one time during the day did the carbon monoxide concentration reach a significant figure. During the time of the morning when truck engines were being operated in tee garage a concentration of Q*G2$ GO In air was noted, 2* The highest concentration .of lead in the garage air was found at h $ Q sum* That concentration was 1*10 milligrams of lead per 10 cubic meters of air* 3 * Immediately after all operating trucks had been removed from the building,, the lead in the air dropped sharply In concentration* 4 * Samples taken on different days at tee same hour of the day show the concentration of lead in the air to K- 0005471 '.it 1)* 0 * 5 1 milligrams per 3.0 cubic meters of air in the garage Just outside the stock-room door and 0 * 0 6 millltrams per 10 cubic meters of air in the garage near the gasoline pump* '3. Analysis of dust deposits for lead shew 1*59 percent lead by weight in dust settled on stock-room cabinets next to the paint-shop wall as compared with 0.80 per emit on the cabinet on aisle away from the wall and O.lj.6 percent two aisles away from the v/all. 6 . The highest concentration of l e a d f o u n d in dust d e p o s i t s a s 7 V? p e r c e n t by weight in t h e dust scraped from outside U :a lass i n the paint-shop s k y l i g h t . This 1 c o m p a ra b le with 2 .0 2 p e r c e n t found-i n similar scrapings from the s t o c k - r o o m s k y l i g h t . Other d u s t d e p o s i t s such as garage f l o o r s w e e p in g s * d u s t c o l l e c t e d f ro m m a c h in e s I n the machine shop an d from th e c a b i n e t s near th e battery s ta n d ranged between 0 .1 1 a n d 0*55 percent l e a d content. discusslor? of results r e m the above statement of results It Is possible to draw reasonably definite conclusions regarding relative exposures to inhalation of lead particles and fumes in the garage of the Consolidated Telegraph and Electric Subway . Company* > 1 * The time of maximum lead exposure occurs at the time when there is the maximum of activity in the garage and is simultaneous with the maximum esposure to carbon monoxide ...as* At the time of this study the time of maximum activity -ms between 7?30 and 8*30 a.m* while trucks were w g 0005472 warming tip in the garage preparatory to leaving, At this time th sources of dust In the air were the engine exhausts and dust stirred frosa the garage floor by motion of the machines and men within the building Dust from both of these sources are known to contain small amounts of lead. 2 The place of maximum lead exposure by refer mace to analysis of both suspended and settled dusts Is centered near the paint shop Particularly, analysis of dust deposits give very definite Indication of the paint shop as the center of mximos lead concentration This conclusion Is apparently contradicted by the conclusion that the time of maximum concentration occurs at a time of maximum activity In another part of the garage* This apparent discrepancy ma y fe accounted for by the fact that all parti esulate load emitted by the exhaust of engines la of so small a sia .& to remain almost indefinitely suspended In the air and be carried out of the garage by exhausted air in the same manner as a gas would be* Thus the portion of atmospheric lead dust attributable to engine exhausts would not form on appreciable part of the lead contained in dust deposited In the garage# KG' 0005473 2, The Lead Content of the Blood and Urine of Two Employees in Garage of Consolidated.Telegraph "and Electric " Company - Hew York City Purpose of the observations Study of the lead content of air samples as described in another section of this report relates to conditions in the garage during the short period of the observations, while analytical data on dust samples from floors and other surfaces where deposition occurred, al though concerned with longer periods of time, are always questionable in their hygienic significance, by virtue of the fact that some or all of the lead in such dusts can be derived from sources which are in ho wise hazardous to workmen. For example, large particles of lead-contain ing material fall out of the air rapidly, cannot be inhaled and therefore are of relatively little importance. For the reasons above, and for others as well, the degree of lead absorption of workmen who have been exposed regularly to the conditions which are under exami nation, constitute the best possible measure of the magnitude and significance of that exposure over any prolonged period of time. In this case there was a special point in favor of examination of workmen, in that two cases of alleged lead poisoning had developed out of exposures that had occurred some months previously. The test of those exposures could be made only in terms of other 0005474 2- workmen who had been employed during that period and who presumably had been subject to the same occupational conditions* (The experimental and factual background for these statements has been given elsewhere and need not be discussed here.) Selection of workmen for study Careful consideration was given to the employ ment records of workmen, and although more extensive observations might have been made with profit, it was decided for various reasons to select two men on whom ddterminafcions of the lead content of blood and urine were to be made. S.Vif,, a night foreman, had been employed in the garage for 11 years, and had been exposed to any lead hazards which may have existed during that shift and that period of time* A**, had been employed as stock-keeper for a period longor than m y other person* If there had been any special conditions of lead exposure he should have experienced them* Any serious occupational exposure, sufficient to produce lead levels in the blood and urine such as had been reported in the men suspected as having lead Intoxi cation, would confidently be expected to leave some trace of their exist noe in the two workmen S.W. and A.W* who were presumably exposed to the same occupational conditions* K6 0005475 3 Procedure and Results ' Blood and urine samples were taken for analysis by physicians of Consolidated Telegraph and Electric Com pany, in containers supplied by this laboratory, and in accordance with the following instructions* INSTRUCTIONS FOR. COLi iUCTICtf OP BLOOD POR LEAD ANALYSIS Blood samples must be taken in a space which is free of dust. Despite this precaution it is necessary to use the most meticulous care against the contam nation of samples with surface or atmospheric dusts. The subject or patient must remove any dust laden clothing before entering the room in which the sample is to be taken, and must wash hands and face or any other parts of the body that may be dusty. The cork should be removed from the tube in which tne blood is to be drawn only during the withdrawal of the blood, and should not be permitted to come in contact with the table top or any other potential ly unclean surface but should be held by its toumost part or laid down within its filter paper wrapping, and replaced as soon as the blood has boon obtained. The filter paper cover should be replaced and secured around the neck of the tube by means of a rubber band. The sterile needle provided in a second tube should be used withdraw approximately 10 cc of blood directly into the blood tube. Under no eireums ancas may any anticoagulant or other substance ba added or any intermediate container be used, nor may the needle be sterilised by boiling in water. If the ' latter should be rendered non-sterile accidentally, it should be flamed gently before U 3 e . After use it may be rinsed out with cold water and returned to the tube. Cotton should bo placed at either end and around the hub to prevent breakage in trims!t. The blood sample should be labeled with the name of the patient and the date and hour at which the sample was taken, and packed with care to see that the cork is secure, and that breakage may notoccur in transit. The sample should be mailed to Dr. Bobert A. Kehoe, Kettering Labors ory of Applied Physiology, -k INSTRUCT! OHS FOR TUB COLLECTION C'F SPOT SAMPLES OP URINE FOR LLAD ANALYSIS Urine samples must be taken in a space which is free of dust The subject or patient must remove any dust laden clothing before entering the room In which the sample Is to be taken and must wash his hands *nd face or any other per tion of the body that may be dusty Approximately 100 cc of urine should be voided directly Into the samp lie bottle In the presence of the physician or attendant The stopper (and the protec tive cover of filter paper) should be removed and held by its tip in the hand of the attendant so that it may not be contaminated through contact with desk table or other object. It should be restored to the bottle as soon as the sample has been obtained, after which it should be covered with the filter paper shield Ho preservative or other material may be added to the sample The bottle should be labeled with the name of the patient and the date and hour at which the sample was taken, and packed with care against the possibllity of breakage in transit The sample should be mailed to Dr. Hobart A Kehoe, Kettering Laboratory of Applied Physiology, College of Medicine, Eden Avenue, Cincinnati, Ohio The results of the analyses are tabulated below: Concentration of Lead in Blood and Urine Identification Lead In Blood Lead In Urine Mgm/100 grams Mgm/ liter E.W. A.W. 0 .0J+5 O.OI4.5 0 .0^5 0 ,0 8 5 5 maousaion The lead concentration in the blood samples is quite within the range of values found in normal persons with no occupational load exposure, (normal rai go 0,01 mgm to 0 ,0 6 mgm. Mean 0 .0 3 mgm.) The lead concentration in the urine samples is likewise within normal limits In both instances, Ihe one Is higher than the other but this variation in the two is vml 1 within the limits of variation for normal persons, and .vIthin the limits of variation for the same individual at different times, if due allowance is made for the smallness of the samples. The range of normal values for spot samples normal individuals is from 0,02 mgm to 0,11 mgm per liter with a mean value of about O.olj., but with some slight seasonal /arialion in the mean, i.e. slightly higher in summer vhon the urinary volusue is reduced, Theactual level of urinary lead xcrotlon of these two men could best be determined by repeated observations on larger samples. However, experience has shown that the correlation of a blood sample with a single spot urine sample is generally adequate for the purpose of determining the "acts with respect to lead exposure, since the blood value varies little from hour to hour, and thereby serves to fix the significance of the urinary result. It is apparent from these results that neither of the men under examination has had any recent lead exposure orthy of consideration. In view of this fact it seems highly KT Q 0 0 5 4 7 8 6 improbable that any conditions of lead exposure sufficient to cause significant lead absorption, and capable of in ducing load poisoning, have existed In the garage in question ithln a period of the year preceding these observations* t-xp rimontal evidence is av? liable to indicate that the lapse of .. cr somewhat more is required for the reaisaption of normal levels of lead excretion after some months of hazardous ! a'I ox:>o3ure. ) fanor^i fc.-r.clual: ns m compared to garages in general, this garage vun in -xcall-mt condition with respect to cleanliness and "oil : :*,;n. ho paint-shop was quipped with special vontl- devices of a type which on inspection seemed adequate sner.il manner of handling the painting was such as *o 'i*a no occasion for anxiety as to load exposure* nothing *n r,ur rosuits would indicate the existence of significant ic d exposure from this source* vbsorvatl n indicated that exhaust gases from pr..ting automobiles were disposed of satisfactorily except for u short period during which a considerable number of cars a r m i n g up and going out at once* She analyses of the a*r ith reference to carbon monoxide and lead, verify these *-- *. `*"v r e a si_.na _ . demonstrate that the conditions in this garage ** 9 Vf*r" similar to those prevailing it: a very large number f '.ub.lialiments in all parts of this country and others* KH 0005479 T The prevailing load concentrations in the air or the garage are of a magnitude which has not boon associated with the occurrence of even, the milder symptoms of lead into*lest Ion, and can o q said to have no significance as occupational hazards. Literally thousands of garage mechanics are exposed daily co such conditions without evidence of clinical illness and without sigas of materially increased 2 ad absorption. Cur fifteen youra of study of this problem and of search for oases of significant human lead absorption under conditions of occupational lead exposure comparable to these, have failed to reveal the occurrence of a single case of load Intoxication among garage mechanics and other employees of garages. More over, our study of the lead excretion of such workmen has given negative results, in that no evidence of increased lead ab sorption or excretion, comparable to that readily found in workmen In the hazardous lead trades, has been discovered* The conclusion is justified, therefore, that the conditions of loud exposure existing in this garage at the time of these observations, and apparently for a con siderable period of time previously, were not suoh as to result in the cceurranca of lead poisoning among th men employed therein. July 13, 1940 Kf 00054SO Signedi Director Kettering Laboratory of Applied Physiology