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1. This pamphlet is confined princi-pally to a discussion of methods of de-tecting lead poisoning hazards throughchemical-physical tests and analyses,safeguarding lead processes throughproperly designed ventilation and ex-haust equipment, and selecting andtraining employees to work safely inlead exposures. While the effects of leadon systems of the body, manifestationsof poisoning, and avenues of lead ab-sorption into the body will be listed,such presentation is only for the pur-pose of indicating the importance ofadequate protective measures.

Properties of Lead and LeadCompounds

Z. Lead and its compounds areamong the most widely used materialsin industry. Metallic lead is silverygray, very soft, and has a very low ten-sile strength. The density of lead is11.34 (19.94"/4"C.), its melting pointis 327.4oC. (621.32oF.), and its boil ingpoint is 16Z0oC. (2948oF.) at atmos-pheric pressure. Lead is only veryslightly soluble in either cold or hotwater, while it is soluble in nitric acidand hot concentrated sulphuric acid. Itwithstands the action of most acids toa marked degree at ordinary tempera-tures. Molten lead gives off noxiousfumes of lead and lead oxide (in mea-surable quantities at 800oC.) and thequantity of fumes increases with thetemperature. The crystaline form oflead is monoclinic. (See paragraph 48and Figure 1.)

3. While lead is the softest of allbase metals used in the commercial arts,it is also the heaviest. It contracts con-siderably on cooling; hence, it is notadapted for casting in the unalloyedstate, if shrinkage is important. Leadis very malleable and may be beatenout to any desired shape, but it can beeasily torn since it lacks tenacity. Onexposure to air, lead oxidizes quickly,

Health Practices Pamphlet No.Published by National Safety Council, Inc.

20 North r$/acker Drive, Chicago

This pamphlet is one of more than 15OSafe Practices and Health Practices Pam-phlets. It is a compilation of expcriencein accident prevention from many sources.It should not be assumed, however, thatit includes every acceptable procedure inthe field covered. It must not be confusedwith American Standard safetv codes:federal laws; insurance req,rire-ents istate laws, rules and regulations; andmunicipal ordinances. Add.itioral copiesof tbis Pam|hlet are aaailable to membersof tbe National Safety Council, Price 25celtts per copy, less in qaantities.

and its oxide forms a protective coatingwhich limits, to some extent, furtheroxidation.

4. Galena, or lead sulphide, is themost widely distributed form of leadore. This is found principally in Eng-land (in Wales and Derbyshire), in theUnited States (principally in Missouri,Idaho, Utah, Montana and Arizona, andalso in Illinois, Oklahoma and someother states), and in Spain and Ger-many. This ore is usually found inquartz veins or limestone beds. Anotherlead ore found in the United States iswhite lead ore, or cerussite (lead car-bonate).

5. Lead has many compounds whichare used in industry, and where theseare encountered a lead hazard mayexist. Among the commoner compoundsare the following:

Lead acetate (srrgar lead)Lead arsenatcLead borateLead carbonateLead carbonate, basic ( rvhi te lead)Lead chlorateLead chlorideLead chron.rate (chrome yellorv)Lead chromate, basic (chrome rcd)Lead c1'anatcLead cyanideLead dioxideLead fluorideLead monoxide (rnassicotite)Lead monoxide, basic (litharge)Lead nitrateLead oleateLead, red (miniurn)

3

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Lead silicateLead stearateLead suboxideLead sulphateLead sulphide

6. There are many other compoundsof lead that may be used in industryand which may possibly set up a leadhazard. Among these are lead azide,lead bromate, lead bromide, Iead dichro-mate, lead dithionate, Iead formate,lead hydroxide, lead phosphate, leadselenide, lead thiosulphate, Iead tung-state, and others. While most of thesecompounds do not have wide applicationin general industrial operations, theymay, nevertheless, be used in quanti-ties for certain industrial and chemicaloperations. Where this is the case, pre-cautions should be taken against expos-ure of employees to lead hazards. (SeeFigure 2.)

7. Tetraethyl lead deserves separatediscussion. It is the only type of leadcompound that will be absorbed quicklythrough healthy, unbroken skin. It isan oily, liquid, organic compound oflead that is dangerously volatile at ordi-nary temperatures. For these reasons,it is a highly dangerous material andlhust be manufactured and handledwith great care against inhalation ofvapor and contact with the skin. Thechief use of tetraetiryl iead is an anti-knock for mo.{or gasoline. It has alsobeen used in small quantities in themanufacture of other chemicals. Regula-tions governing the use of tetraethylIead have been developed by the princi-pal manufacturers of the compound.These regulations are rigid and shouldbe closely followed. (See "Regulations

for Handling and Mixing Ethyl Fluid,"isued by the Medical Department, EthylGasoline Corporation.)

8. The presence of lead in com-mercial products is sometimes unknownto the management, the foreman, or theworkers because the label or descriptiongives no indication that lead is present.

(Copyrights 1929, 1942, National Salety Council, Inc. All r ights reseraed. Printed in U.S. A.)

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As a result, employees maY, throughignorance, be exposed to a serious leadhazard, or may even contract leadpoisoning before it is discovered thata lead compound is in use. SuP-pliers of lead-cpntaining materialsshould issue definite warning of the leadcontent by clearly worded labels; andpurchasers should insist on this practice.

Manifestations of Poisoning

9. Some knowledge regarding theaction of lead on the body and thesymptoms of lead poisoning is valuableto the industrial hygienist and otherpersonnel charged with functional re-sponsibility for results in safety work,notwithstanding the fact that these areprimarily the problems of the industrialphysician, For this reason, the discus-sion in this pamphlet is confined princi-pally to the prevention of lead poison-ing, but there is a brief treatment ofselected portions of the medical aspects.

10. In considering the effects of leadon the body, it is important to recognizethat there may be individual variationsin susceptibility. This and other fac-tors, such as length of exposure, havemade it diffrcult to establish a standardpoisonous dose of lead which wouldapply to all persons and conditions.There are, however, generally acceptedmaximum permissible limits for 8 hours'continuous exposure. (See Paragraph

HEALTH PRACTICES PAMPHLET NO. 3

Courtesy Eagle Pitcher Mining & Smelting Co.

Figure l. The uses of lead in industry. (See paragraph z.)

38.) The effects of the toxicity of leadmay be widespread. The followingsystems of the body may be concerned:

BloodGastro-intestinal systemNervous systemCardio-vascular system (heart-circula-

tion)Urinary systern (particularly the kid-

neys )Reproductive system

11. The first thing the layman mustrealize about lead poisoning is thatthere is no one subjective symptom orobjective clinical sign which is positivelyindicative of lead poisoning. In somecases so-called "chronic" lead poisoningmay be one of the most difficult of theoccupational diseases to diagnose. Aphysician must make the diagnosis inthe light of the history of lead exposure,occupational or otherwise; subjectivesymptoms; objective clinical signs; andinformation based on laboratory tests.

I2. There are, however, generalmanifestations of the poisonous effectof lead absorption. It should be remem-bered that whenever there is lead ex-posure there is potential danger fromabsorption of the lead. The degree ofdanger depends upon the extent andduration of exposure and the controlmeasures in effect. Some of the com-moner manifestations of lead absorptionare listed below. Where these mani-festations are noted. the individual

should,at once be referred to a physi-cian for thorough examination and anynecessary treatment.

a) Disturbances of the digestive system,in the form of lack of appetite, con-stipation, vague abdominal discomfort,and in more severe cases sevefe cramp-ing abdominal pains (colic).

b) Pain and stiffness in joints, bones,and muscles (particularly the musclesmost used.)

c) General weakness, loss of weight, andpallor.

d) Loss of strength in the fingers, hands,or forearms, and inability to use themin the performance of customarytasks. (See Figure 3.)

e) Damage to the blood, possibly caus-ing anemia.

13. In addition to the manifestationslisted above, there rnay be nervousness,muscular twitching and tremors, partic-ularly of the fingers. The incidence offever is rare, but there may occasionallybe a slight jaundice and sometimes in-creased blood pressure. Sometimes inlead encephalopathy (disorder of thebrain) irritability, excitement, delirium,convulsions, and ocular disturbancessuch as amblyopia or blindness occur.

14. Active lead poisoning cases mayfall into one of the definite types famil-iar to industrial physicians, but the co-existence of more than one type is alsorecogaized. This merely emphasizesthat the above recital of manifestationsof lead poisoning is for use in preven-tion of the occurence of disabling dis-eases and that there should be thoroughmedical supervision of all employees ex-posed to lead hazards. It is obvious thatwhere cases of lead absorption are de-tected during the initial stages, the in-dividual can be removed from thehazard and the onset of lead poisoningprevented. Even where individuals arethought to be exposed to only a minorlead absorption hazard and are referredto a physician, urine and blood testsmay indicate too much lead absorption.Here, again, when the victim can beremoved from the exposure and ade-quate treatment given, development oflead intoxication will be prevented. (Seeparagraphs 17 and 18.)

15. The second point which shouldbe clarified is the difference between"ingested lead," "lead absorption," and"lead poisoning." Lead found in thefeces is an evidence that some lead haspassed through the gastro-intestinaltract without being absorbed by thebody proper. (See paragraph 21.) Ab-

sorption of lead is indicated by leadfound in urine or blood examinations.Lead poisoning begins when the lead inthe blood and the body organs actuallybegins to exert harmful effects. Leadpoisoning is also refe-rred to as "plum-

bism" or lead intoxication. Absorptionof too much lead into the blood indi-cates that action must be taken to pre-vent further absorption by eliminatingthe source, and that medical treatmentmay be necessary to prevent the leadfrom causing systemic damage.

16. Lead absorption and poisoningmay be indicated on physical examina-tion by the finding of a typical leadline in the gums. The lead line undermagnification will stand out as a dis-tinct row of blue dots in the gum tissuenear the tooth margin. Absence of alead line does not necessarily indicatethat lead absorption has not taken placeand, too, according to one authority, ifa lead line is absent in a mouth wheremarked oral sepsis exists, it usually in-dicates that there is no serious amountof circulating lead in the body.

17. Lead absorption is also in-dicated by lead in the urine. Hereagain, the results of such eiaminationsmust be judged by physicians in thelight of clinical symptoms. In normalindividuals with no occupational expos-ure, lead in the urine may range from0.01 to 0.08 milligrams per liter, andoccasional values as high as 0.10 milli-grams per liter, the normal average be-ing about 0.035 milligrams per liter.Lead concentrations in the upper rangeof normal values, i.e., well above themean value, while not definitely indica-tive of occupational lead exposure,suggest the advisability of further inves-tigation to establish the facts with refer-ence to lead exposure. It is necessarythat the samples tested be obtained bythe most scrupulously careful meansunder the direction of an experiencedperson. Otherwise contamination of thesamples in the process of collection iscertain to occur. Depending upon thesize of the plant, this supervision mayfall to the industrial physician, chemistor laboratory technician. The source ofabnormal lead absorption must beclearly established, and here considera-tion must be given to the possibilitythat lead may be absorbed from otherthan an occupational exposure.

18. The amount of lead in the bloodas a criterion of lead poisoning is fre-

quently brought to the attention ofpersonnel and safety men in connectionwith employees who are being routinelyexamined for lead absorption. In thenormal individual, according to one au-thority, blood lead values will rangefrom 0.01 to 0.06 milligrams per 100grams of whole blood with an occasionalvalue as high as 0.07. The mean valuefor the normal individual is approxi-mately 0.03 per 100 grams of wholeblood. Here, again, the advice of aphysician is necessary since investiga-tors have found that even where 0.15to 0.2 milligrams of lead per 100 gramsof whole blood are present, the individ-ual is not necessarily suffering from leadpoisoning. But this is an indication ofa possible lead hazard and action isnecessary to discover and eliminate it.

Entrance of lead into the body

19. Lead and its compounds can betaken into the body by inhalation, in-gestion or absorption through the skin.Inhalation is now recognized as by farthe principal means of absorption. Theinhalation exposures, however, offergreatest possibilities for improvement orcontrol by engineering means. In spiteof the high amount of lead which mayenter the body by inhalation, as com-pared to either ingestion or absorptionthrough the skin, users of lead com-pounds should not assume that the dan-ger is negligible where only an inges'tion or absorption hazard. through theskin exists. Alsorption through theskin is important in the case of leadtetraethyl and other organic lead com-

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pounds. If sufficient lead is ingestedday after day because of improper per-sonal hygiene, lead poisoning will cer-tainly occur. Likewise, if lead tetraethylor possibly other lead compounds arehandled carelessly, absorption will takeplace through the skin in sufficientquantities to cause poisoning. (It hasbeen stated by one authority ttrat ab-sorption through the skin is a factorwhere actors paint the whole body.)Where the skin is scratched or irritated,it is possible to absorb considerablymore lead than if the skin is undam-aged. Where tetraethyl is used, thishazard is acute and must be guaqdedagainst. (See paragraph 7.)

Inhaled lead

20. When minute particles of leadand its compounds are inspired with air,much of it is carried into the mouthor throat and is either swallowed, ex-pectorated, or blown out with the ex-pired air. The remainder is drawn intothe lungs and deposited on .the lungtissues. Lead in the lungs is capableof rapid absorption and distributioninto body tissues, since here it is inintimate contact wilh the body fluids.Lead, after dissolving ih the lung fluid,is absorbed by the blo'od, and then cir-culated through the body. When thisoccurs, the lead is dangerous and iscapable, in sufficient quantities, of pro-ducing systemic damage.

Ingested lead

2L Where lead is swallowed, thegreater part of it passes unchanged into

Figure 2. Exhaust system and stationary soldering irons protect these workers fromlead fumes. (See paragraph 6.)

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Figure 3. Illustration of wrist drop. (SeePangraPh tz.)

the gastro-intestinal system and thusis eliminated in the feces. The greaterportion of the lead which is absorbedfrom the gastro-enteric tract is carriedto the liver. It eventually finds its wayinto other tissues of the body and alsoback into the intestines by way of thebile. Lead in the blood may be de-posited in the bones or body organs, orbe eliminated through the urine. Wherelead remains in the body, a high pro-portion of it is ultimately deposited inthe bones. Authorities differ as to howdamage to the body may take place sub-sequent to the deposition of lead in thebones. Some have suggested that theflow of lead may be reversed from thebones into the blood (where it may, ifpresent in sufficient quantities, causelead poisoning), because of acidosis,changes of diet, or respiratory illness.Other authorities doubt that the abovefactors are chiefly responsible for themobilization of lead from the skeleton.It is generally agreed, however, thatpersons 'lvho may have lead depasiteclin their bones, or who are exPosed tolead poisoning hazards, should bestrongly advised to refrain from over-indulgence (particularly in alcoholicbeverages), and faulty diet.

Dermatitis from lead comPounds

22. I\{etall ic lead itself has nevcrbeen reported to cause dermatitis, butsome of the lead compounds cause skinirritations among tvorkers handlingthem. Schwartz and Tulipan, in "Oc-

cupational Diseases of the Skin," statethat skin eruptions have been reportedfrom contact with preparations contain-ing lead acetate, and that lead arsenateand lead chromate may cause occupa-

HEALTH PRACTICES PAMPHLET NO. 3

tional dermatitis. Dermatitis has beenreported as occuring among munitionsworkers from lead azide and leadstyphnate. It is believed that the

. dermatitis caused by lead compoundsis due to the acid radical part of thecompound rather than to the lead.

' 23. According to Drs. Fairhall andSayers, who have conducted extensiveexperiments, all lead compounds do nothave the same relati,ve degree of toxic-ity. Some are highly toxic, while othersare toxic only after lirng exposure. Thesetwo authorities, in United States PublicHealth Bulletin No. 253, "Relative

Toxicity of Lead and Some of its Com-mon Compounds," have developed, asthe result of their experiments, a tableof the relative toxicities of certain leadcompounds based on their solubilities,which should be of particular interestto industrial hygienists and toxicologists.

24. Regardless of the relative toxic-ity of lead compounds to which an in-dividual is exposed, lead poisoning canand will occur if sufficient concentra-tions of lead compounds are breathed,or if the worker swallows sufficientquantities over a long enough period. Itshould not be considered that preven-tive measures can be neglected or evenminimized because the compound in useis allegedly less toxic than others.

25. According to some authorities,the comparative toxicity of lead com-pounds is based on a number of vari-ables, the most important of which istheir solubility in the body fluids.Among the other factors affecting thetoxicity are:

a) Porta l of entryb ) Quan t i t y p resen t i n t he c i r cu l a t i on

-.--jt ""r' *t":.,]'r;

c) Speed wi th which compound goesinto solut ion

d) Size and weight of par- t ic lese) Length of t ime in contact wi th body

f lu idsf) Quant i t l . inhaled ol swal lowedg) Degree of acid i ty of body f lu ids

Determination of Concentrationsof Lead in Air

26. Where lead or lead compoundsare used in industrial processes, it is im-portant to know whether the measuresof control in effect are adequate to pro-tect the men exposed. Then, too, it ishighly important at times to evaluatea possible hazard to determine whethercontrol measures are necessary. Con-centrations of lead in workroom air canbe determined by accepted methods ofcollection, and subsequent analysis.Two devices in use for air samplingwhere lead is, or is thought to be, pres-ent, are the impinger and the electro-static precipitator. The former is ingreater general use, but the latter isconsidered more efficient for fumes. (Forfurther information, see Littlefield, J.B., Feicht, P. L., and Schrenk, H. H.,"Efficiency of Impingers for CollectingLead Dusts and Fumes," Bulletin No.3401, published by the United StatesDepartment of the Interior, Bureau ofMines, May, i938.

Impinger

27. The impinger was originally de-signed by Greenburg, of the UnitedStates Public Health Service, and Smith,of the United States Bureau of Mines.There are now several varieties of theoriginal design, but all operate on thesame principle. An air sample is drawnthrough a collecting tube at a measnred

F, - l P , Z

Courtesy Illinois State Department of LaborFigure 4. Impinger for lead sampling.

rate of flow and is discharged undera liquid tlrough a taper-pointed tube,whicl impinges the air and its entrainedimpurities against a glass plate or thebottom'of the collecting flask. When arepresentative sample has been taken,the flask is disconnected from the ap-paratus and transported to the labora-tory for analysis. (See Figure 4.)

28. Irnpingers may be obtained inseVeral sizes, the one selected depend-ing upon the volume of air that mustbe drawn through the apparatus to geta iepresentative sample in a measuredtime. Two sizes are generally used, cali-brated for a maximum flow of one cubicfoot per minute, and 0.1 cubic foot perminute, respectively. The latter type isknown as the "midget" imPinger'

29. The sample of air to be testedmay be drawn through the impinger byone of several methods: a compressedair ejector, an electrically driven bloweror vacuum pumP, or a manuallY drivensuction pump. The hand-operated suc-tion device is of especial value for fieldwork where electrical power or com-prgssed air is not available, or wheresamples must be taken in a flammableor explosive atmosPhere.

Electrostatic preciPitator

30. The electrostatic precipitator isespecially adapted to the collection ofItiad fumes. As in the case of the im-pinger, there are variations of construc-tion and design of precipitators, but theprinciple of operation is the same foreach. One precipitator which has beenused in the field. and is available com-mercially, consists chiefly of a smallblower to pull in the.air sample, a pre-cipitation chamber, and a power supply.The precipitation unit is-essentially agrounded cyfi ndrical -qettTe tube whichacts as the collecting electrode and acentral electrode which acts as the ioniz-ing and precipitating electrode. Thecentral electrode has one end spun inthe shape of a bullet-nose and containsa small platinum wire extending fromthe spun end. Both electrodes are smallaluminum tubes. For sampling, the elec-trodes are placed in a head which issupported on a telescoping tube whichfunctions as an air connection to theblower. Particles collected are given anelectric charge as they enter the pre-cipitation chamber and are then forcedto the outer electrode in a much strongerelectrostatic field. Air flow is measured

LEAD

after passing through an orifice, by amanometer located near the head. Suc-tion is obtained by use of a vacuumtype motor and blower. Power supplyis obtained with a transformer. (SeeFigure 5.)

Technique in collecting samples

31. The collection of samPles witheither the impinger or the electrostaticprecipitator is a job for a highly trainedand skilled technician. Pfecise tech-nique and a thorough knowledge of thepitfalls to be avoided are an absolutenecessity for accurate sampling. Sam-ples must be truly representative .ofthe average conditions of exposuret(preferably taken in the breathingzone), not merely indications of highor low concentrations at certain times.For this reason, tle samples must betaken under normal operating condi-tions and over a period that will givethe average exposure (sometimes an en-tire shift must be covered) and' too,care must be taken that normal ventila-tion is'not disturbed by the samplingoperations. The concentration of leadpresent also is a factor in governing tlesampling time, for where not much leadis present, samples must be taken overa longer period to get measurable quan-tities for analysis. Great care must beexercised to prevent contamination ofsampling equipment before and afterthe sampling period if the results are tobe accurate. (For a complete descrip-tion of the technique in using an im-pinger and electrostatic precipitator, seeBrown, Carlton E., and Schrenk, H. H.,"A Technique for Use of the ImpingerMethod," Information CiralJar 7026,Bureau of Mines, 1938, and. Drinker,P.: "Alternating Current Precipitatorfor Sanitary Analysis. An inexpensiveprecipitator unit." Iournal ol IndustrialHygiene ond Toxicology, 14, 364,1932.)

Methods of lead analysis

32. There are a number of generalmethods by which collected lead may bequantitatively analyzed,; the followingfour of which are probably best known:the colorimetric (dithizone); the spec-trographic; the volumetric (Fairhall'schromate) ; and the dropping mercuryelectrode. Many of the generalmethods, including those just enumer-ated, are applicable for the analysis oflead in biological materials after suit-able preparation of such samples.

Courtesy Mine Safety Appliances Co.

Fieure 5. Electrostatic dust sampler out-fit-for lead fumes. (See paragriph 3o.)

33. Various investigators have estab-lished standard chemical procedures forthe separation of lead from othermetals, as the chromate, sulphide, orsulphate; and the subsequent determi-nation of tle lead by colorimetric, titra-metric, or turbidimetric techniques, in-cluding several modifications. Theseprocedures are successfully used onlyby skilled and careful analysts. Per-haps most widely used among thesemethods has been the dithizone(diphenylthiocarbazone) colorimetricmethod, of which there are more than50 variations. It is sensitive enough togive results even where the concentra-tion of lead is extremely low, involvesrelatively simple manipulations, and isspecific under controlied conditions.

34. The dropping mercury electrodemethod of analysis, utilizing the polara-graph, is coming into wider usage, es-pecially for routine urine analysis. Ithas in its favor a comparatively simpletechnique and greater speed in the finaldetermination of lead. However, thismethod, like others, necessitates timeand care in the preparation of samples.When capably employed this method issaid to yield results as accurate as thoseobtained by the dithizone and spectro-graphic method. (See Figure 6.)

35. Spectrographic analysis of ma-terials containing lead results in a highdegree of accuracy in the hands of a

ftp-s-o-\

Figure 6. Polarograph for determinationof lead. (See paragraph 34.)

capable technician. The equipment isirighly specialized and very sensitive.

36. Various modifications of theFischer-Leopoldi method (making useof dithizone as a means of extractinglead quantitatively from its aqueoussolutions to form a color complex), havebeen developed in recent years and havecome to occupy an important placeamong procedures. The method is suf-ficiently sensitive to be used to deter-mine minute quantities of lead in smallsamples of urine, blood, and tissues.When carried out with proper chemicaltechnique, it is specific for lead andquantitatively precise. Several of themodifications have been described instep-by-step detail and can be reliedupon when employed by careful andexperienced analysts.

37. Detailed information on thetechnique of the methods or modifica-tions mentioned above, as well as theseveral methods of analysis and recentmodifications of such methods, not men-tioned in this pamphlet, will be furnishedon request by the National SafetyCouncil.

Maximum permissible concentration

38. The maximum concentration oflead in workroom air should not bepermitted to exceed 0.15 mill igrams percubic meter (or 1.5 mill igrams per 10cubic meters) for continuous exposure.This standard is generally accepted inthe United States; among the severalregulating bodies that adhere to thisvalue are the United States PublicHealth Service, the Connecticut Depart-ment of Health, the Massachusetts De-partment of Labor, the California In-dustrial Accident Commission, the

HEALTH PRACTICES PAMPHLET No. 3

Illinois Department of Labor, the NewYork State Department of Labor, andthe Wisconsin Industrial Commission.

39. Where tests of workroom airshow a greater concentration than 0.15milligrams per cubic meter, check testsshould be made at once to determinewhether the excess of lead found isdue to a permanently existing condi-tion in the process or merely to sometemporary or unusual condition. Wherecheck tests show that the maximumpermissible limit is being exceeded,steps should be taken at once to lowerthe concentration to a safe limit. Aftersafeguards have been applied, routinetests should be made to determine ade-quacy. In determining whether themaximuin permissible limit is being ex-ceeded, it is important that tests bemade over an entire cycle of the opera-tion, and not merely some high or lowpoint.

Prevention

Control of environment

40. The most obvious method ofpreventing lead poisoning is to substitutefor lead and its compounds other ma-terials that are non-toxic. However, thisis rarely practicable, and recourse mustbe had to control of environment andtraining of employees, to prevent theabsorption of lead. .

4I. When new plants are to beerected for lead processes, they shouldbe designed to minimize lead exposure.AII floors should be of impervious ma-t-erial and easily cleaned. Ledges, win-dow sills, structural iron work or otherprojections on which dust might lodgeshould be filled in or angled off. TheIayout of machines anl equipmentshould be such that maintenance ismade easy. Arrangements should bemade, wherever possible, to isolateall lead operations so that the leastnumber of employees will be ex-posed. Vacuum cleaning systems, dis-charging the exhaust air in a safe place.should be built- in while the buildine i ibeing erected, and the wash, locker indlunch rooms should be separate fromthe general workroom. In existingplants where it is not possible to build-in permanent vacuum cleaning systems,portable vacuum cleaning apparatusshould be used. Such equipment notonly makes the cleaning of the planteasier, but in addition makes it possible

to remove dust from walls and ledgeswhich otherwise might not be cleaned.Care must be exercised in dumping orcleaning dross from the vacuum clean-ers, so that a further lead exposure willnot be created. The danger of dust onwalls and ledges, of course, is that somevibration or draft may cause it to beswept into the general workroorn air.

42. In designing locker rooms, it ispreferable that employees exposed tolead hazards be provided with doublelockers, one side for their clean clothesand one side for their work clothes. Aliberal supply of warm water and soapshould be provided, €rnd a sufficientnumber of shower baths and wash foun-tains should be installed so that em-ployees will not neglect cleaning up be-cause of possible overcrowding. (SeeFigure 7, and Safe Practices PamplaletNo. 27, "Industrial Sanitation [Drink-ing Water, Wash and Locker Rooms,and Toilet Facil it ies].")

Ventilation

43. The type of general ventilationand local exhaust equipment applied tolead hazards will depend in great meas-ure on the type of building, the par-ticular compounds used, and the methodof manufacture. There are certainfundamentals which should be consid-ered by the engineer designing the sys-tem. These are as follows:

a) Al l requirements of the state depart-ment of labor in which the olantis located should be careful ly fo l -lowed, and plans should be sub-mit ted for approval where th is isrequired or where the serv ice isavai lable.

b) Care should be taken when layingou t t he sys tem tha t t he a i r i n l e t i sin such a locat ion that only uncon-taminated ai r is drawn into the sys-tem. The in let volume should becommensurate wi th the exhaust vol-ume. Somet imes i t is necessary inco ld wea the r t o hea t t he i ncom inea i r so t l r a t t he exhaus t s1 ' s t em v r . i l lfunct ion proper ly.

c ) I t i s p re fe rab le no t t o r ec i r cu l a te t oother departrnents exhaust a i r f roma department wi th lead exposure.Where ai r is so reci rculated or ex-haus ted d i r ec t l y t o t he ou t s i de i t i shighly aclv isable to insta l l some sJ,s-tem for recover ing f rom exhausta i r t he l ead compound wh i ch i spicked up by the exhaust or vent i la-t ing system to prevent reci rculat iono r con tam ina t i on o f a i r i n t he v i -c in i ty of the plant .

d) The system should be la id out sothat i t is foolproof and so tamDer-

Courtesy E. H. Sargent & Co.

ing by. employees cannot take placewithout d iscovery.

e) On every job where lead dust orlead fumes are given of f , local ex-haust should be appl ied that wi l ll imi t the concentrat ion. of dust orfumes in the breathing zone ofworkers at or below the maximumpermissib le concentrat ion of 1.5mi l l igrams per l0 cubic meters of

. a i r for cont inuous exposure. (Seeparagraph 38.)

f ) Local exhaust systems, when ap-pl ied, should be so designed thatthey wi l l not inter fere wi th theoperat ing ef f ic iency of the generalven t i l a t i ng sys tem and v i ce ve rsa .Cross currents of a i r and dead airpockets should be avoided. I t issomet imes necessary to resort to a i rl ine respirators or masks for cut t ingor rvelc l ing operat ions, part icular l l .where large parts are involvecl . Suchrespiratory protect ive equipment issat is factory, but care should betaken not to expose ot l . rer employeesin the area, who are not protected.

g) Only exhaust and vent i lat ion sys-tems designed by experts in thatf ie ld should be instal led. Repairsto exist ing systems should never bemade by amateul 's . Where statelaws require i t , or where th is serv iceis avai lable, repairs should neverbe made wi thout f i rs t consul t ingthe state department of labor.

h) Al l vent i lat ing, local exhaust , anddust col lect ing systems designedfor contro l of lead exposures shouldbe checked per iodical ly for efhciencyby a qual i6ed engineer.

44. In many cases, exhaust equip-ment for specific operations will haveto be especially designed for the particu-lar job. For instance, Figure 8 illus-trates a ring-type exhauster which ef-fectively prevents lead carbonate dust

LEAD

from spreading into the surroundingworkroom air during loading of basiclead carbonate into metal drums orbarrels. (See also paragraph 53.)

Respiratory protecive equipment

45. For certain classes of exposure,such as general spray painting, spraypainting structural steel, lead burning,cutting and welding of lead-coated steel,and for use during emergency, respira-tors of a type approved by the U. S.Bureau of Mines should be used. Forcontinued protection against lead ex-posures, a properly desigaed, installedand maintained ventilation and exhaustsystem is highly advisable; however,where respirators offer the only prac-tical type of protection their use shouldbe insisted upon. Wherever respiratorsare in use, supervisory attention shouldbe given to making the employees ascomfortable in them as possible; and,particular care should be paid to thehygiene necessary in their maintenance.For lead dust, a lead dust respirator ap-proved by the U. S. Bureau of Minesmay be used. When exposure to leadfumes is involved, the U. S. Bureau ofMines approved respiratory protectiveequipment, such as air line respirators,or abrasive blasting helmets may beused. There is also the problem of mak-ing certain that air supplied to this typeof equipment is clean and free from thecompound against which protection issought. Approved mechanical filterrespirators may also be used for pro-tection against lead fumes. These filtersrequire renewal frequentlS', depending

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Courtesy John P. I.ewis & Bros. Co.Figure 8. Ring-shaped exhaust hoods foruse at top of barrels. (See paragraphs

44 and fi.\

upon the fume concentration. For addi-tional information on respiratory pro-tective equipment, see Safe PracticesPamphlet No. 64, "Respiratory Protec-tive Equipment," and Industrial DataSheet D-Gen. 16, "Cleaning and Steri-lizing Goggles and Respiratory Protec-tive Equipment."

46. A complete discussion on venti-lation and exhaust is not within thescope of this pamphlet. For additionalinformation on ventilation and exhaustsystems, see Safe Practices PamphletsNo. 32, "Exhaust Systems," and No, 37,"Industrial Ventilation."

Other control measures

47. Particular attention should begiven to the possibility of entirely en-closing lead processes so the chance offumes and dusts escaping in the work-room air is reduced to a minimum. Forexample, excellent work has been donein enclosing processes involving lead inthe gasoline and battery manufacturingindustries.

48. When it is necessary to meltlead, the temperature should be heldas close as possible to the melting point,since greater quantities of fumes aregiven off at elevated temperatures. (Seeparagraph 2.)

49. Wet methods of productionhave long been looked on with favor bysome industrial hygienists and indus-trial physicians for preventing the dis-charge of dust in the workroom air.Figure 7. Good wash facilities near lead operations. (See paragraph 42.)

Complaint

Habits

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Where wet methods of manufacture areapplicable, they should be applied, bear-ing in mind the danger of lead dust, ordust of compounds of lead, being throwninto the air upon drying. Examples ofwet methods are oil grinding of whitelead in the paint industry, the Englishand German method of separating whitelead powder (basic carbonate) fromlead buckles by immersing them in atrough of running water, and wet past-ing of lead plates in storage batterymanufacture.

Housekeeping

50. In addition to the installationof vacuum cleaning apparatus, it isnecessary that a regularly scheduledroutine for housekeeping be institutedand followed. Where there is no regularcleaning crew, definite periods shouldbe set aside each day and all men in thedepartment should be required to takepart in cleaning up. The practice of us-ing compressed air for blowing leaddust or lead compound dust from floors,

.HEALTH PRACTICES PAMPHLET NO. 3

walls and ledges should be strictly pro-hibited since this is one of the mostdangerous methods of cleaning, and it iscertain to leave a heavy concentrationof dust in the air. In some plants, suchas in glazing departments of potteries,the walls, floors, ledges, and ceilings areflushed off with a water hose, and allof the material is swept into a centraldrain. (See Safe Practices PamphletNo. 45. "Industrial Housekeeping.")

51. Covered trash cans should beprovided and employees should be in-structed to use them instead of droppingmaterial on the floor around machinesor benches. Dross, especially, should becovered immediately after removingfrom the kettle and should be trans-ported as soon as possible to suitablestorage rooms or reducing furnaces.

52. The practice of vigorouslysweeping up floors in departments inwhich lead or lead compounds are used,should be prohibited. If sweeping mustbe employed, soft push brooms shouldbe used, and the floor should be liber-

ally sprayed with water belore sweep-irg operations are started. Liberalquantities of oiled sawdust are usedin some plants instead of sprinklingwith water, to avoid dust being createdif the water dries before sweeping iscompleted. The men doing the sweep-ing should be provided with and re-quired to wear approved type respira-tors. and should, if possible, performtheir work at times when other em-ployees are not exposed. Vacuum clean-ing is preferable to sweeping.

53. All containers of lead com-pounds should be provided with covers,and should be kept closed at all timesexcept when actually in use. Wherepowdered material is transferred frombarrels to mixing or other process ma-chines, covered scoops should be usedfor the purpose or some mechanicalmeans of transferring should be em-ployed that will prevent contaminationof the workroom air. Ring-shaped ex-haust hoods that fit the top of barrelsmay also be used. (See Figure 8 andparagraph 44.)

Selection and Placement ofEmployees

Physical examinations

54. All employees, before being putto work on operations where there isexposure to a lead hazard, should begiven a thorough physical examinationby an industrial physician. The rec-ommendations of this physician shouldbe followed in assigning to employmentany man who is examined. (See Figure9 and Health Practices Pamphlet No. 2,"Physical Examinations in Industry.")

55. Possible reasons for rejectionfrom employment where a lead exposureexists include lead intoxication, indica-tion of an abnormal content of lead inthe blood or urine, kidney trouble,stomach ulcers, heart trouble, anemia,constipation, venereal disease, tubercu-losis, alcoholism, and &e use of drugs.Pregnant women and adolescent boysor girls should not be employed wherethere is a lead hazard. It should benoted that many of the reasons forpossible rejection from employmentgiven above would also prohibit anytype of employment.

56. Re-examination of employeesshould be made at regular intervals,the intervals to depend on the recom-

Fieure 9. One company has developed and used this special form for employment and" p.riodical examinations of lead workers. (See paragraphs 9-18.)

mendation of the industrial physicianmaking the examination, on the leadexposure that exists, or on state labordepartment requirements. In general,where lead or lead compounds are ex-tensively used in the plant, employeesshould be given complete physical ex-aminations at least once a year, pre-ferably more often, and they shouldbe examined monthly by the plantphysician to determine whether or notlead absorption has taken place. Micro-scopic blood examinations (basophilicaggregation tests, stippled cells) or uri-nalysis should be made and the generalhealth of the individual carefullystudied. Employees should have theprivilege of reporting to the plant physi-cian for a further check-up anytimethey do not feel well. One authoritysuggests that physical examinations begiven every six months where metalliclead is used, monthly where molten leador compounds are used, and everY twoweeks if white lead or red lead is used.(See Health Practices Pamphlet No. 5,"Health Service in Industry'") Wherethe question of frequency of examina-tions arises it should be answered bythe industrial physician, after the engi-neering details of the physical environ-ment have been carefully consideredand evaluated for or by him.

57. The medical department PlaYsan important part in plants where thereis a lead hazard. Hence, its activitiesshould be properly integrated with otherprevention work. The medical depart-ment should act as a check on theefficiency of the control measures in theplant. For this reason, reports of themedical department should be closelystudied and where, in spite of carefulcontrol measures in ef{ect, a high leadabsorption rate is shown by certain in-dividuals, careful inspection should bemade of their work locations for thepurpose of correcting hazards.

.Training of Employees

58. There are certain minimumstandards of education and adaptabilitythat should be fulfilled by the prospec-tive lead worker. These will vary con-siderably from industry to industry, butthe minimum test should be rvhether ornot the prospective worker is adaptableand can be trained to follow safetyrules. For example, inability to speakEnglish greatly complicates the train-ing problem. However, there is no ob-

LEAD

jection to employing non-English speak-ing workers if provision is made fortraining by supervisors or instructorswho can explain the hazards and theproper work methods in the languageof those employed.

59. Once it is decided that an in-dividual is physically and mentally ableto do work in lead processes, the generalhazards of lead work should be care-fully explained. At the same time, com-mon sense rules of personal sanitationand company policy on safety shouldbe presented. Before a man is finallyput to work, he should be examined asto his understanding of these rules bya personnel man or the safety engineer.

60. When individuals are being"broken in" on jobs, a definite pro-cedure should be followed that will in-sure their knowing exactly what is to bedone and how it is to be done. Thisis best achieved by first thoroughly ex-plaining the job and giving the reasonsfor the rules that are enforced. Theemployee should then be given a'chanceto state his idea of what he has beentold; this gives the instructor an oppor-tunity to correct any misunderstanding.The job should then be demonstratedby the instructors, several times ifnecessary, and the new employee shouldfinally be permitted to perform theoperation. Here again, an opportunityfor correction of unsafe practices or in-efflcient work is presented. After the in-structor is certain that the man under-stands and can do the operation safelyand effrciently, he may be permitted towork alone. but he should be checkedfrom time to time to make certain thatall safety and health rules are obeyed.The same procedure should be followedin transferring workers from one de-partment to another or from one opera-tion to another. (See Safe PracticesPamphlet No. 65, "Teaching Safety toNew Employees.")

Personal hygiene

61. Personal cleanliness of the ex-posed portions of the body, the finger-nails, mustaches and hair should be in-sisted upon. Employees should be urgedto take a shower each night beforeleaving the plant and to change fromtheir work clothing to street clothing.Where lead dust collects on the cloth-ing and hair of employees, it may getinto the workroom air lvhen the cloth-ing is brushed or shaken.

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62. The medical department may,from time to time, issue bulletins onthe subject of proper diets for workersexposed to lead and its compounds. Insome exposures this may include therecommendation to drink milk. Theworkers, too, should be urged to getplenty of sleep and as much sunshineas possible.

63. Employees should be forbiddento use tobacco (smoking, chewing orsnuff) while in the plant, except thatthis may be permitted in the regularplant lunchrooms or in other designatedareas during lunch hour, alter employeeshave thoroughly cleansed themselves.

64. Eating in a workroom wherelead is handled should be absolutelyprohibited. It will be difficult to en-force this rule unless a lunchroom isprovided where employees can eat incomfort. In many plants, lunchroomshave been provided in which employeescan purchase, at moderate cost, a nutri-tious and properly balanced meal.Lunchrooms should be isolated from anylead expcsure and employees should becompelled to wash their faces and handsthoroughly before eating. In some cases,it may be desirable to urge employeesto change clothing before eating.

First aid

65. There is no recognized first aidfor lead poisoning. AII cases of sus-pected lead absorption or acute attacksshould be immediately referred to aphysician. To delay proper treatmentmay lead to complications.

Supporting activities for naining

66. The personnel, medical andsafety engineering departments shoulduse every facility for stimulating andmaintaining the health and safety in-terest of employees exposed to leadhazards. For example, applicable postersshould be used on centrally locatedbulletin boards, and should be changedregularly to maintain interest.

67. Other media for maintaininsinterest and training employees (manyof them available through the NationalSafety Council) are:

a) Payrol l inserts containing healthhints. Wheru paying by check somecompanies cl ip the insert to thecheck.

b) Sound f i lm s t r ips o r mov ing p ic tu reson indus t r ia l hea l th and sa fe ty .

I

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c) Company publications.

d) Talks by outside engineers, plantengineer, plant medical officer, orIocal safety council iepresentatives.

68. It may be thought that toomuch effort directed toward trainingemployees through the use of meetings,literature, rule books and other mediawill focus attention upon an existingoccupational disease hazafi. This hasnot proved true in many large com-panies where hazards of the operationwere carefully explained and the meth-ods for avoiding them made clear.(See Safe Practices Pamphlets No. 67,"Maintaining Interest in Safety," No.77, "Safety Meetings," and No. 93."Topics for Safety Meetings.")

HEALTH PRACTICES PAMPHLET No.

ACKNOWLEDGMENT

Thi,s pamphlet has been reai.sed byErnest I. Doztni,ng and John M. Roche,IndustriaL Di.aision, National, SaletyCounci.l, lollowi.ng the work oJ a speci.alcommi,ttee ol whi.ch Harold Ohleheiserwas chairman. The origi.nal dralts werereai,ewed by members of the speci.alcommi.ttee. Thei.r aaluable assistanceand the original work ol th.e committeei.s gratelully acknouledged.

The first d.ralt ol the reaision uassubrni.tted Jor criti.ci.sm to the Sale Prac-ti,ces Conlerence Comm.ittee, the HealthPracti.ces Conlerence Committee, andauthori.ti,es on the suhiect of lead. Tlte

3

final draJt was approaed by the Erecu-tiae Committee ol tlte National SaletyCounci.l.

Liberal use has been made ol thepubli.shed material and personal com-ments ol Drs. Robert A. Kehoe, DaaidC. Strauss, Elston L. Belknap, S. F.Meek, Lawrence T. Fairhall, R. R.Sayers, Loui.s Schwartz, I. C. Aub,Leonard Greenburg, Alice Harni,lton,Carey P. McCord., Ludwi.g Teleky, A.G. Kammer, Mi,lton H. Kronenberg andH. A. Cranston and others. The sug-gestions and help given by these authori-ties were i.naaluable in the preparati.on

oJ the pamphlet.

Rvn. 7-42-3M