Document KRnGwy3Zy0zvzK5nj3RbzdMmN

FILE NAME: National Safety Council (NSC) DATE: 1940 Oct DOC#: NSC068 DOCUMENT DESCRIPTION: Excerpt - Transactions of the NSC - 29th National Safety Congress I \ I \ P-N SC -9 TRANSACTIONS 29th c ^ -(' NATIONAL SAFETY -CONGRESS GENERAL AND INDUSTRIAL SESSIONS CHICAGO OCTOBER 7-11, 1940 - ^ 1 NATIONAL SAFETY COUNCIL, 20 North Wacker Drive, Chicago Copyright. 1?<0. Ntionl Softty Council. Inc. Print in s U. S, A. INC. al Safety Congress tv Council, October j . Volume I contains of the various la me II contains the icrcial Vehicle, the me Safety Sessions. all industrial mein' members who arc sessions it contains, mav obtain Volume dvantageous to disics to the individual their organizations, formation the vol ition programs. The dard reference mamay be obtained as. '2 each ; 11 or more ne II mav he had at ire the proceedddresses and many ) delete extraneous muons. and emphn in promoting eli'ee nt prevention mens what abridged ver ir value to the stu in achieving more Hie original nianucnee, if desire 1, h ,'ongresses. seeks to eh are not pertinent y be contrary to the ccept responsibility papers presented or JNCIL, Inc. j l c' < ^;G22 Contents Council Officers and D irectors...................................... 4 Council Purposes and Program...................................... 9 Annual M eeting of Members.......................................... 11 Annual Banquet ................................................................ 27. General Subject Sessions-- Agricultural S a f e t y .................................................. 29 Building Maintenance.............................................. 47 Eye Protection .......................................................... 63 Fire Control and Prevention.................................. 79 Fundamental Causes of Accidents........................ 91 Governmental Safety Service in Industry........... 107 Health Service in Industry.......................................119 Industrial N u r sin g .................. 129 Maintaining Interest in Safety............................... 151 Occupational Disease ...............................................165 Off-the-Job Accidents .............................................183 Plant Transportation ...............................................197 Psychology and Safety (Early Morning Classes) .................................................................209 Safety B e l t s ................................................................ 245 Safety Su p ervisors.....................................................253 Safety Training ........................................................ 261 Visual E d u c a tio n ........ ............................................. 277 Aeronautical S e c tio n ........................................................ 285 A.S.S.E.--Engineering Section .....................................301 Automotive and Machine Shop Section.......................305 Cement and Quarry Section.............................................319 Chemical Section ...............................................................327 Construction Section ...................................................... 353 Food Section ...................................................................... 375 Marine Section .................................................................. 397 Meat Packing, Tanning and Leather Industries Section .............................................................................427 Metals Section .................................................................. 445 Mining S e c tio n .................................................................. 497 Paper and Pulp Section.....................................................549 Petroleum Section ...................................... 591 Power Press Section...........................................................625 Public U tilities Section.................................................... 635 Refrigeration Section ...................................................... 659 Rubber Section .................................................................. 671 Steam Railroad Section.................................................... 697 sxtihe*SccwoH TV. m . . . - . .................................................723 Wood Products Section.................................................... 739 Safety Exposition E xhibitors.........................................743 Index .....................................................................................749 ' .v: o! prompt and continuous delivery of essen tial weapons of defense we must nor only train new workers and retrain older work er.. but we must restrain accident*, uj,;^ inner away our supply of skilled hands producing these weapons. Maximum Allowable Concentrations of Dangerous c Industrial Dusts and Gases A A By A L IC E H A M ILTO N , M.D. E> Medical Consultant to the U. S. Division of Labor Standards, W ashington, D. C. C 1 have been asked to make a brief sum and only rarely colic. This amount, you s, C mary of our present-day knowledge with re was not to be taken as safe, only as fret c gard to dangerous degrees of air pollution from serious danger. In 1933 our own Pub. c from gases, vapors, dusts and fumes, and he Health Service concluded that the the data which have been secured so far as amount of lead (lust or fumes in the ilr c to the maximum allowable concentration -hould be kept 0.15 mg. per cubic meter lor e which can be assumed to be within safe lim -afety. This was on the basis of ail invest, c ditas.ngbeerloouws dthuestsdaanngdervappooirnst.haAvefebweenofstuthde gsiactkionnessosftuadysotofra2g,3e03bmatetenryemppllaonyte,d atnhderej. F ied intensively enough to afford us fairly full For "prolonged exposure," the figure most, f- data on which to establish such standards, it seems, be still lower, for some cases were t bthuetmonoluyr aknofewwl,edagnedisevneont cwomithplerteeg, aarndd tiot fouI nbdelwiehviechthheadnedxetveimloppeodrtaenvtencoanttri1b2utmep L would be a great mistake to embody in legal in this field was made by tlic Benzol Conk C regulations the standards which we arc at mince of the National Safety Coundlf f present tentatively recommending, for it is which, as you all remember, established 100 f certain that, as our knowledge increases parts per million as the maximum allowable through investigations in this field, we shall concentration for benzol. That figure stl f have to change our figures, I believe that stands, though we have a good deal of ent ( the State departments of labor or of health dcncc that it is too high. You arc probably r wcohnicchenthraavtieonasdroepgtaerdd stthaenmdaardssadovfisaolrloywoanblyle, dfaumstirliiaalr bweintzholtwpooisreomnianrgkawbhleichrepapoprtesaroendin F and that is right. 1939; one from the Massachusetts State De The first attempt at the establishment of a maximum figure of air contamination by an industrial poison was made in England in 1910 by Duckering and Legge, who used '.he procedure since generally adopted; that they determined the amount of lead in the air of a workroom and matched it up with the record of lead poisoning in that room. In this way they were able to state that, if die amount of lead were kept under 0.3 mg. partment of Lalxir on benzol in the manu facture of shoes; the other from the St* York State Department, on benzol in roto gravure printing. In both studies cases os discovered that had developed after ex posure to concentrations below 100 ppm. d* a result, Dr. Francis Hunter of Boston or dared that, "It is doubtful whether any cc* ccmration of benzene greater than zero " sate over a long period of time." ;er cubic meter of air, there would be no The American Standards Association b> serious plumbism, no palsy or encephalopathy had for some years a committee on this American Standards Association Committee Parts per Million L&rajtfa of exposure. S u b sta n ce i IOO Carbon monoxide ! 400 Not over 6 hours daily Benzol ; 100 . .8- - Carbon disulphide ! zo Hydrogen sulphide ZO ........................... m mmn m Governmental S a fe ty Service in Industry 111 cstram accidents, w|,jr| supply of skilled hands .pons. Suggested Standards f o r Illinois and Massachusetts Parts per Million Milligrams SCpbicMetw Mass. Illinois Mass. Dangerous ix jb s r a o c e Ammonia 50 IOO Aniline 5 5 W ashington, D. C. Benzol 75 75 fo o d d*nwriwM) Carbon tetrachloride IOO 100 ic. This amount, you see, :cn as safe, only as free Chlorine 0.35 Chloronaphthalenes 1.0 5 1to5 er. In 1933 our own Pubce concluded that the ust or fumes in the air - mg. per cubic meter for Chlorpdiphenyls Chromic acid Gasoline 5 1.0 1.0 0.1 1000 1000 n the basis of an investi- Glycols 25 gc battery plant, and a .'.303 men employed there, posurc," the figure must, Hydrochloric acid 10 Hydrocyanic acid 10 10 wer, for some cases were Hydrofluoric acid 3 3 Icvclopcd even at 12 mf. \ t important contributioo nadc by the Benzol Com,'ational Safety Council vC- - Lead (Mercury (Methyl alcohol 1.5 1.5 15 1.5 100 200 remember, established 100 i the 'nximum allowable her, That figure still avc i good deal of evi- j high. You are probably ct- '( _ Nitrogen oxides Nitro benzol Ozone Phosgene 10 10 5. 1 1 remarkable reports on inisoning which appeared m Massachusetts State De- on huizol :u the mami- Phosphine Sulphur dioxide Tetrachlonethane 2 10 10 IOO 200 tiic other tram the Xe* unent. on b-.nzol in rote- 'ii lioth sluuic.' eases ut** md develops after ex- Tetrachlorethylene IOO 200 Trichlorethylene IOO 200 Toluol 75 200 *ntion* below 100 ppm* Turpentine 500 200 cis Hunter c: Boston de* Xylol IOO 200 loubiiul \vh:her any co0,'cnc greater than zero ** Zinc oxide 150 15 period of time." Standards Association ht a committee on this so. I?-1, tomposed o i industrial physicians, ven can be realized practically while a more tilation engineers, industrial insurance car- rigid standard would be rejected, and we nittee ners and toxicologists, who arc trying to set should be left with no standard a: all. My up standards for use in industry. self, I am always willing to accept half a vf exposerc irborsdiig-- a 'u ' ar V,G ^,ave dealt conclusively only with two gases and two volatile solvents. _ ^ y l9 L S c r2 x id i -and hydrogen sulphide, ,nzo' and carbon disulpliide. The limits Ptea for the present arc shown er. the accompanying chart. Benzol stands a; 100 cr:ieHy because of the insistence o: our durance uiemhers that this is an idea! that loaf rather than no bread, but Manfred Bowditch. of the Massachusetts Eurcau ot Occupational Hygiene, is unwilling to go higher than 73 ppm., and Yandcil Hender son. of Yale, enters an emphatic protest against 100 ppm., saying that if 20 ppm. is feasible for hydrogen sulphide and carbon disulphide, lie can see no reason why it is I9ih Xtitioiial S a fe ty Caiu/ress Tentative Standards Adopted Bcj Public Authorities Tbr Maximum Allowable Con centration Of Silica Containing Dusts 'Authority Millions 5^ Particles pwCaFt of Air Free Silica Content" j High M edium Low Matiooal Silicosis Confer aniline * group- W the other CCl-t, ab. more. At comes eli pharmacoi non-toxic fection wi dustrial po ence. 1936. Medical Com m ittee. .............................. - 5 ....... -10 to 2 0 - : -- .......... Ditto. Engineering Committee.......5 ....... U. S. Labor Department I93S Division of Labor Standards--------------- NeuiVork Department gf T - 1 ........ Labor. 1940...................... 'am-* -10 to 3 0 - , .................. t | i ......15-....... - ............--- -- 10....... -j-- -1 0 0 - Connecticut Department o f Public Health. 1936.----- " - - 5 ..... --- California Industrial Acci- , - . To pass field, silice fact, so ev: that there agreement amount of dons of fre a workshop ing from ga . not take lift silicosis may . from the ai affect the d L-dust. dent Commission. 1936. -- 5 ............ - -50 Wisconsin Industrial Com-' mission. 1932........ ........... -- 5-......... --- 15 ---- --------------- Massachusetts Department: : o f Labor 6' Industries 1940......5 --....... -- 10----- -- 1 0 0 -- , (g ra n ite ) 25 S5" foundry 'WNjr?f N uisance Dusts impossible ior benzol. Certainly :: is to be hoped that ventilation engineer-.? -ill pro gress to tile point where a lower figure than 100 ppm. may be reasonably demanded for benzol users. standard ior carbon monoxide does not need to be defended. This gat has been exhaustively studied by the Public Health Service, by State bodies, by industry and by toxicologists in many universities. Carlton disulphide and hydrogen sulphide arc the two dangerous gases which must be dealt with in the manufacture of viscose rayon, and the maximum allowable concentrations given in the chart were established through careful studies made by the American Vis cose Corporation, the dtt Pont Company and the Tubize-Chatillon Company. When it comes to the other toxic sub stances I have listed here, we can ;ay only that the figures given represent our best judgment at the present moment, but we ad mit that that judgment is often based on something not far from guess work. Take the one on which I happen to be engaged at the present time, tctracliloreiliane. We know it is the most dangerous of the chlo rinated hydrocarbons used in industry, and we have known since the first world W what its action is on the human body, for ii was used by both the Germans and tbr British in airplane dope, and in both coun tries gave rise to cases of acute yeilo' atrophy of the liver; but, in spite of i voluminous literature and an impressi'* number of clinical cases, we find no stance in which the amount of poison in th{ air was determined. Therefore, the-saandarf ten parts per million, is based on Zang?r; statement that this solvent belongs " lt:; j^U-Take four .Xrifllica, runnir ^dangerous g; r^yias^for centu ;jase" of stone 'foiindrv w j&of this panic t^'Hatch and Ml ?TtJon for the d. \ and other sii: \ shown tiie si! chiefly in the 1 particle size d till it may r microns, only fifth of the pe microns. This foundry du<t c chipping, jobs 1 the industry kr foundries are r more chipping i: If our knowl acquired to proc fying, this is sul *bat constitutes f'ons- Here the ) mK much valual |ntJ'tal investiga-. rnming, have car lnd, in cooperati Governm ental S a fe ty Service in l ndustrx 113 h of far .OW ,,iliac arai nitrobenzene in the most toxic -roup- Wc "avc ' ' ttlc ^'1U rc8arci t `'la; other chlorinatctl hydrocarbons, except ]4, about which we do know somewhat more' As to the other-, our knowledge comes ehieriy from the studies made by pharmacologists who sought a relatively non-toxic agent for cases of hookworm in fection which is not the same thing as in dustrial poisoning from fumes. IOO- 50- '5 uadrtj .U san ce Yu s t s represent our best moment, hut we ad- is often based on ; guess work. Take ppen to be engaged .trachloreihane. We tgerous oi the chlo-cd in industry', and the first world war human body, for it Germans and the . and in both coun* s ot acute yellow but. in spite of a and an impressive vs, we find no M" - -* of poisoa-ia-'1''* re fore, the standard, based on ZangSri vent belong? with To pass over to that very controversial field, silicosis, I need hardly emphasize tiic (act, so evident in the accompanying dtarts, that there is still much confusion and little agreement among the authorities as to the am ount o: dust containing varying propor tions of free silica that may be permitted in a workshop. This is to be expected. Poison ing from eases and fumes, even if slow, docs not take fifteen years in make itself evident: silicosis may. Moreover, other factors, aside ' i.from the actual proportion of free silica, "Caffect the dangerous character of a given .'dost i.T.Take ioundry dust. It may be rich in' fisilica, running as high as the notoriously srdangerous granite, yet. while consumption ?Yhas for centuries been the occupational disfease of stor.c cutters, this has not been true to f foundry workers. Recent brilliant studies yl'of this particular dust, notably the one by ;:-Hatch and Moke, have provided an explana tion for the difference between foundry dust and other silicious dusts, for it has been shown the silica content of the former is . chiefly in the large dust particles, and as the particle size decreases, the free silica falls, till it may reach, tor particles under 2 microns, cr.iy onc-fifth or even one twentyfifth ot the percentage in particles over 10 microns. This is, however, not true of the foundry dut caused by sandblasting and by chipping, jobs which everyone familiar with the industry knows to be dangerous. Steel foundries are the worst, probably because more chipping is needed on steel castings. If our knowledge of the minimum dose required to produce poisoning needs ampli fy?. this i; still truer of our knowledge of what constitutes dangerous dust concentra!10ns- Here the Public Health Service is do"t? much valuable work. Their two monu ~ f 's>Soi~rtivi*tigations. oi the Vermont granl,e. Industry and of Pennsylvania anthracite mining, h;/./carried us a long way forward, and, in cocperation with, rhe experts of the Saranac Laboratory, they have found it possible to establish certain fundamental facts. For instance, the Laboratory is able to state that the percentage of tuberculosis tn be expected among workers in an establish ment where there is no special dust hazard, is 479 per cent. If the rate is higher, there is something wrong; of course, not neces sarily dust in the air; perhaps low wages. Donald Cummings, of Saranac, urges the adoption of two limiting concentrations of free silica; first, the "primary threshold," a concentration of dust in which a health) man may be employed throughout his work ing life without a disabling injury; second, the "secondary threshold," a concentration in which a healthy man will "inevitably contract silicosis if regularly employed for several tears.'' General experience shows tiiat the first is at about five million par ticles less than ten microns in diameter; the second is proliably at a level not higher than 100 million. At the National Silicosis Conference held in Washington in 1938, this formula was suggested for determining the maximum permissible concentration of free silica in the air breathed. Multiply the percentage of free silica by the total small particle dust count by impingcr. If the result is under 3 million, the condition may be looked on as permissible. Ii it is over 5 million, the con dition is to be looked on as poor. For ex ample, 10 per cent free silica with an av erage total dust count of 30 million particles would mean 0.1 times 30 million, or 3 mil lion. good practice: while 30 per cent free silica ami 50 million particles would mean 13 million, too much. This formula cannot be applied to a dust with less than 5 per cent silica. Botli New York and Massachusetts have made fairly recent studies of the foundry industry and of work with granite, such as quarrying and stone cutting, tunnel and foundation excavating. New York recom mends for dust containing less than 10 per cent free silica, 100 million particles; for 10 to 70 per cent. 10 million; for 70 per cent and over. 5 million. Foundry dust, averaging 20 per cent free silica, should be kept down to 23 per cent; the dust from abrasive .blastcleaning. averaging 70 per cent down to 10 million. Massachusetts allows 25 million inr foundries, 10 miiiion for granite stone milland 3 million for pure silica dust. H OT 4iiB' 114 29th National Safety Congress Source o f Duaf |Percent of CLsr+z Suggested Sandart) (Free Silica) In Million A rticles (Below 10 Microosjper !Cubic Foot- o f -Air. Gold dines. South fifties------86 to 95------ 3 to 4.5 million Chief Metal Mines. BrokeaHillj Australia--------------- -10 to 17- 14 Tunneling, Sydney. Australia--------------- -90- Cinder G Gold M ines.Ontario- _i 255 ttoo 31050(*2 nin-es))!; ------S.5 Iron. Mines. Canada -- 50 ------- 5 Granite Cutting.Barre (Rock,25) Vermont Dust. Average 35 - 9 to 20 y. Metal Mines. Tri-State Area -90- Potteries. West Uirgieia. -2 0 to 30 A nthracite nMi*ne-s~. Pennsylvania. ;(RDQuCskr4930/%iCCcOaSll..2Q-4%Z | quartz) R o c k U Jo rh e -j dust average 55 Subway and Foundation] Drilling. (NewYork City Less iban lto64. -5 tolO -10 We must not forget that tile adoption of any of these standards docs not mean that there will be no silicosis among the work ers. In the South African gold mines, the free silica in the air was brought down to 3 to 4.6 million particles per cubic foot by 1933, but cases have continued to develop, taking 14 years now, on an average as against an earlier average of 9yi years. In Barre, Vermont, the Public Health Service found cases appearing after only ten years at 6-9 million particles and after 9 years, at 20 million. They have placed the maximum allowable number of particles at 9 to 20 million, which is certainly not extreme. I need not say anything more about the great need of careful studies of actual coo- I '-::ions under which damage from poison* j and dusts occurs in industry, it is in out ] country that these studies must be (Trade : he day is past when we could look to Ger many as the source of knowledge of indus trial toxicology.-'Now that authoritative, j ' '.sition has passed to us. And tin's partic"- I '.or method of determining safety limits means of a combination of experts in sev eral fields, chemists, ventilation engineer*' ;-..-.d physicians is peculiarly American. other country has made anything like contributions to this branch of industn* hygiene that we have. But we need a deal more. The ti been "D no other democra' ical fash State inc ine ever at one t; the role States a law" to year aftaccident: over and By oro mobile I method lawed th it a pri machine meeting 10,000 c ideas an Democra "Demc Justrial tional p: and ern before i. industry fit its p foot the use the , lion. There o uruic and res'ventions Governr ,exbc Am- taiemer uiacturc ciaiion all sir oced Gi already ctuiremc out whi methods .i have taken a ),. man's mind. 1 cessary lor me to rry certainly p|aj, accidents. 1 am my accidents those we had not tain difficulties. But l \ job for them but safety program u ting rid of tho Occupational Disease WEDNESDAY MORNING SESSION ' October 9, 1940 " The meeting on Occupational Disease. Vlanned as a Panel Discussion, was called to order by the Chairman, Walter S. Paine, Manager, Engineering Department, Aetna Casualty & Surety Company, Hartford, Conn., who presided. Vf * . union is almost & fetv program, "? Panel Discussion tali ration and sid- in about the sane n working in vot ate job, he is not money and has i nsibilities. His doc e going to have la out." The doctor1) be $25, $50 or p-Is going to have ceks, and there VriS ay . That is -i CHAIRMAN P A IN E : At every meeting bat I have attended in this Congress some one has raised the question of industrial dis- This is a subject which has been . -'`maligned in some cases and has been a fan- on the part of others. This, however, ild not in any way destroy the realities Ipta are back of the industrial disease proh- ^gjn/the discussion of this broad problem, fgn'.have asked the medical profession and- law to help us this morning. Each phase Considered as Industrial Injuries?" This will be handled by H. A. Nelson, Director of Workmen's Compensation Department. Wisconsin Industrial Commission of Mad ison. We all regret that severe illness keeps Dr. Paul Brchm, Supervisor of Industrial Hygiene Unit of Wisconsin State Board of Health at Madison, from being present. The panel will be opened on "Health Hazards in Spray Painting." Dr. Walsh. 3 ^ 'the problem will be discussed on an or- ring the time be h iierly basis. We liavc assigned as the firs; ;ivc a defintte side 'Speaker for each of these subjects one of the iws he is going k men on this platform. After he has finished benefit, he is * b bis preamble, we will ask the members on : to go ahead the floor to present any question they may out: and, again, u bvebn the subject. a favor ar.d yoo physical ccnditior- .We have the following subjects to Ik- ;licm do play a P*"*1 pused: "Health Hazards in Spray Paint- program. g." Dr. Eugene Walsh, Associate Surer- If : Ladies md Ckn- t'so' of Medical Service. International 1------ 1 mors- * harvester Companv, Chicago, will open this interest tr.~- rm" t mbject. ient satisfAacntiioonn i1`- - _ . . ' | ,i.,t (t-.t Ch**' 1 -. tll'gue and Its Relation lo Occupational Spray Painting DR. EUGENE W ALSH: Palming i< a topic that has received considerable atten tion. There lias been an increasing number of hazards imported into the trade. Mo-i of these have received wide attention, par ticularly In the past few years. It lias Uvn incident to the wide use of the -pray gun and of tiie lacquers, particularly. Many of the solvents and products used in the paint industry have known toxicitics. Others are in the experimental stage, so far as u-e and so far as their hazards to health arc con i,'in to turn to ti*1 t This subject will be taken up by cerned. chili of the P'1' ' TA Norbert Enzcr, Director oi Laboraire jgi.ajn tvh.a.t lbtB :1 ;_ ** Mo"TuInt mSinai Ho-spital, Milwaukee, iot more d icus' Ivi. le Toxic Limits of Common Solvent-.'' ibis pauei- . r t i '1 su^)*ut will be opened up bv Dr. In the old days of brush or dip or flow painting, -till widely used, solvents of rather low volatility were employed, and the haz ards associated therewith were not a- great. i good pa" ,f | . ' tDn Belknap, of Milwaukee. However, when we come to the spray gnu. ; will be I"bb- . ."Dad in. Industrial Processes." Dr. Bvi- particularly in its use in the recently devel also bandle this subject. oped lacquers, we come into a lio-t of ju-.w -r=~-- 'Affections." This will he handle'! -olvcnts. ! J,, ,.r' M. J. Reuter. Dermatologist i } . -WUologist. of Milwaukee. \Y k %l'i-c1 U. but one ui die most iinport::r'. Shrmid Oerojm.nonal Ihsea-e- ! The quantities used per year in lacquers and solvents in the paint indu.-tr;. .:i ihe United .Stales reach astronomical roimrlions. Many, inanv ion. are used. 166 29th National Safety Congress In the paints we have the following haz ards : first, the pigments. There has been a growing trend definitely away from leadbearing pigments toward non-lead pigments. Many of the non-lead pigments have their peculiar hazards. Many of them are rela tively innocuous and can be used with rela tive immunity. So far as the fluid constituents of paints are concerned, in the order of volatility in general, we have, first, the solvents which are, largely, for paints; the. paraffins; oils and varnish; varnish with some turpentine or some spirits of various and sundry types. The lower the volatility, of course, if it is a toxic product, the greater the toxicity. The ordinary paints and lacquers can be considered together because the problem of the solvents, largely, is what we wish to deal witJt. The solvents used are relatively low boiling products w hich volatilize rradily, such as acetone, ethyl acetate, butyl acetate, amyl acetate, and so forth. Next, the paint must have a diluent. In the ordinary paints--oils, turpentine or spirits may be used. In the lacquers--alcohol, toluol, xylol, mineral spirits have been used. In the past, benzol was used. We are glad to say that there is a growing trend away from the use of benzol, which has cumula tive actions in the human individual, result ing in the low grade chronic toxicities due to a depression of the blood-forming organs. There is a definite trend toward less toxic diluents. The next essential part of the lacquers in cludes the driers, such as ethyl lactate or cellusolve, monomethyl ethers and various other chemical products of known and un known toxicities. Also, there must be a flexilizer or a substance giving flow to the . plastic. These are relatively high-boiling lowvolatility products, triphenylphosphatc, cas tor oil, camphor and others, again of known and unknown toxicity. The toxicities of the various individual products are often known. It is not the toxicity of the pure product, however, that we are often concerned with. It is the prod uct which is used commercially. It is often the impurities in minute quantities that add to the toxicity'. For example, we may say there is, in the case of xylol, some question as to its inherent toxicity. However, since benzol is so frequently a contaminant, wc do have some benzol toxicity to be consid ered when xylol is used. Also, when have two substances which arc used to a paint or lacquer fluid, its toxicity, resi. ing from the combination of the two ^ stances is not usually that of a summaa, of the individual toxicities of (he two. T~j is, if we have two products (A and B), lie viewpoint of the panel 0n this subject, namely spray painting ? EDWARD SM ITH ilalleable Co., Buffalo, N. ,-as made about spraying one-plus toxicity, if we wish to use DR. W ALSH: Sprayin terminology, and B of one-plus toxicity, * is a common procedure, may get a resulting toxicity of three-#* , largely calcium, it is a rc or something of that nature--just to use* substance. It is irritating arbitrary form.----------- j f i tree and may be follow The methods of control are; First. 4 substitution of non-toxic products such a we mentioned in getting away from !<jp hearing pigments in paints. We are !oi to have alert chemists in the paint indzaj who are alive to this problem. They a constantly striving and working with the* dustrial hygienists and the physicians ia cough. Not infrequently ; aunts in whitewash whici products in them but, sashing is a matter that i; seek, and perhaps a mor done in most industries d exposure is relatively in hazards are not great. veloping non-toxic products, so far as id . Likewise, most of the 1 pigments and solvents arc concerned. "Jj dures are done in large, Another factor that has been consideri.! That isn't true of some t and is of importance today in redox}*;.".J1f itis .d,one in c-l-o--s-e-d- rc- toxicity is the mechanical d c v e l o p m e z t V f s poor oration, the spray gun. Many years ago, ;n its.- I the process is to consun fancy, no precautions were taken. The J1Jtime, to have the indivit gineers weren't particularly interested * S ' ibme manner. Just a simp A man would spray with one or aaoti] It mechanical dust type rt spreading the toxic substances about T oij ysmuld be usable if the cx however, with the development of loirer anylength of time. pressure spray guns, with the develop of engineering methods of control of vrp.'lV X-Ray Examir and fumes and dusts incident to the proetta. i DR. ROBERT M. BL we have less toxicity. . 'State Medical Assn., St. ) If an individual corporation is alert is (hire methods by x-ray serving and controlling the hazards P'rfk dtie to time or from yea: very little toxicity need be encounter! r 'tow progress of bronchi: most processes. This includes, of C0Ufiil?V n*to{ these paint inhalatk precautionary methods for the in d ij^ t'I; DR/W ALSH: There when I speak of the industrial liygic'.aj r f .would answer your quest: the engineer's phase of the problem- "f. live. Most roentgenologist individual is working in a place at the idea of mak: ginecring methods are not feasible to ,- "Oochlectasis by x-ray. T the vapors and toxic products, then dividual must have his respirator)' r a W**osoedt..i.n...t.h.e x-ray are la tion to ..prevent inhalation. Most ^ \essds and fibrous solvents which are uscd~TuTve J ; v . J lru. however, action, and their action is hv '*?' fra*! ik* _ * 1 did nwohticrhr. sorption through the respiratory ing away the fumes is the way 1 j t t f f >^haTrCC_la_m indus1 f have very briefly outlined some ip r.-j** a silic,sicanother ,p,rr' major points. Do you choose to Pu" cp i M^JAstic ch3n,,^ ^a,lr question? *fg ; O l i v e r , t ? CHAIRMAN PAINE: D is c u s ^ * 1 * ? *kirW d f rd be carried on from the floor and .< *ne*cs50in th -Lm. Occupational Disease 167 used. Also, when vhich arc used to m :id, its toxicity, rest atiort a t the two si . that of a suromat cities of the two. Tl .ducts (A and B), A we wish to use tl .t one-pius toxicity, toxicity of'three-pv nature--just to use V control are: First, .oxic products such a$ .ting away from lead, aims. We are fortunate -,s in the paint industry tis problem. They are td working with the in:d the physicians in dcroducts, so far as both is arc concerned. at has been considered anee today in reducing rhanical development of ny ----- s ago, in its in- s taken. The tn- :u.w ./ interested in it. ;y with one or another, substances about. Today, development of lower -. with the development ads of control of vapors s incident to the process, rporation is alert in obne the hazards present, need be encountered in ; includes, of course, the ods for the individual : industrial hygienist and e of the problem. If a ng in a place where cn:re not feasible to control ic products, then the in- his respiratory protec-.halation, Most at the : used have a narcotic ction is hy way of ahe respiratory- tract. Tabs is the way of control, fly outlined some of the ou choose to pursue this ! this subject, namely health hazards -spray pamtmg ? :%DWARD SM ITH (Jewell Alloy & i 'alleable Co., Buffalo, N. Y .): No mention made about spraying whitewash. -L-qR. WALSH: Spraying with whitewash j common procedure. As whitewash is '^largely calcium, it is a relatively innocuous Yfobstance. It is irritating to the respiratory ii* and may be followed by a chronic rerchugh- Not infrequently there are contam inants in whitewash which may have toxic fjroducts in them but, ordinarily, whitekyishing is a matter that is done today, next ^rcek, and perhaps a month hence. It isn't dtxie in most industries day after day. .The .{exposure is relatively infrequent and the ^lizards are not great ^Likewise, most of the whitewashing proi?JjiCfdures are done in large, open, airy rooms. pSThat isn't true of some tunnels, of course, iff it is done in closed rooms, tunnels and "places with poor aeration, it is advisable, if the process is to consume any length of time, to have the individual protected in Isome manner. Just a simple draft of air or .a mechanical dust type respirator probably would be usable if the exposure is to he of any length of time. X-Ray Examinations DR. ROBERT M. BURNS (Minnesota State Mr-iica! Assn., St. Paul, Minn.) : Arc there methods by x-ray examination from time to time or from year to year that will show prezress of bronchial trouble as a re sult of these paint inhalations ? DR. WALSH There are those that would answer your question in the affirma tive. Mot roentgenologists, however, rather scoff at :hc idea of making a diagnosis of bronchiectasis by x-ray. The shadows which we s the x-ray are largely those of the blood vessels and fibrous structures of the lung. It ;s true, however, if an individual is using seme paints which bear silica--and foe pair.: that I did not mention is that used m the porcelain industry, silica-bearing paint--that is another problem. I f you are using a silica-bearing paint, you will get the characteristic changes of silicosis. A1NE: Discussion "'ill the floor and also from ; However, for the ordinary pigment, so little It absorbed, so few of them produce Proeri-i.ivc changes in the lung, they rarely show on the x-ray. Most of them are stopped by the mechanical aids in the nose and upper respiratory tract, that is the hairs, the cilia on the lining of the respiratory tract and, as such, are coughed up, rather than persisting in the respiratory tract. However, it one is using paints over a long period of time, it is conceivable that a chronic bronchitis might result. However, here one is on thin ice. There are many other factors incident to the causation of chronic bronchitis that are equally as, or more, important than the products used in the paints, either the pigments or the sol vents. MR. CARR (Eastman-Kodak Company) i In spray painting in rooms, using lead-free gasoline as a solvent, we have noticed as much as 450 parts per million of aromatics, and we find that many lead-free gasolines now sold contain a large proportion of ben zol, xylol and toluol. I wonder if much at tention has been given to that fact? DR. W A LSH : That is a problem, it is true. Certain fields of oil, particularly those bearing the naphthionic acid oils do, in their cracking processes, result in benzol in con siderable portions, in some instances, in the gasoline. The straight paraffin oils may re sult in some benzol but not so much. It is a factor to be considered. It depends largely upon the amount of benzol present. In some instances it has been said to run as high as 10 per cent in certain gasolines. That is not usually true. There is one factor to be considered in gasolines, and that is the difference between benzol, which is the ring-structure and ben zene,- which is a straight hydrocarbon, and relatively innocuous. It has some toxic prop erties, but they are transitory, largely. Benzol has developed a chronic toxicity. This particular subject is receiving attention now, but very' little has been produced to indicate that benzol is a definite toxic agent in the gasolines produced. But if the aro matics were up to about 450 parts per mil lion, you certainly are on the borderline of toxicity. I think it should be reduced, if it is at all possible, by ordinary' methods. A t--least the men should be watched very care fully for blood changes, so far as benzol exposure is concerned. MR. CARR: In that connection, it has been necessary for us to go to a respira- w isz- i'*S i W T 4 '-^ ;S S '"** 8'rKiU.r w*'.. 3 II f Si 4i Biv?:' 16S 29/A A ational S a fe ly Congres tory protection o the supplied air type, sup plied also with a charcoal canister at the man's waist, so that when he breaks the connection temporarily to go back in the room, he still has the protection of the char coal canister. The connection, when broken, automatically shuts off both the air supply and also the air connection, so that he can not breathe the room air. MR. W ALSH: That certainly is a fine arrangement. DR. ALICE HAMILTON'" (DivisiofToY Labor Standards, U. S. Department of Labor, Washington, D. C .): In the Division of Labor Standards in Washington some two or three years ago, when I was visit ing automobile plants, I was told they were making a change in their coatings. I wonder whether that has proved to be true? They told me they were substituting synthetic resins for nitrocellulose and as a solvent were using hydrogenated petroleum prod ucts which had very low volatility. It seemed as if that were going to be a revo lution in coating in automobile factories. I should like very much to know whether that change has been made. CHAIRMAN PA IN E: Can anyone an swer the question of Dr. Hamilton? DR. W ALSH: I would like to say to Dr. Hamilton concerning the substitution of synthetic resins for nitrocellulose products in the automotive Industry particularly, most of us receive all of our information concerning the newer development of haz ards from no person other than Alice Ham ilton. If anyone in the room can answer the question, I am sure that she can. She beau tifully reviewed the entire literature in a publication that she produced in 1936 called "Recent Changes in the Painter's Trade" which is Bulletin No. 7 of the U. S. De partment of Labor. It is a beautiful presen tation, and it is worth while for any of you interested in the paint industry to read it. Concerning the question at hand, I know of no particular changes at the moment that have been instituted in the industries that I have been acquainted with. I do know that such things are in progress. As Dr. Ham ilton suggests, I think that they are changes in the right direction, in many instances. DR. A. L. BROOKS (Fisher Body Di vision. General Motors Corp.) : We do quite' a lot of spray painting. I believe there has been no radical change in the solvents and diluents used in the lacquers which we lrt now employing. The process is very much? the same. There has been some change in the lengthA of time required to dry these lacquers, but^i the constituents are the same as they -gr W. H. KRAUSE (AUis-Chalmers Company, West Allis, W is.): There h;vji been recent changes in regard to the diluent*?used in paint. Quite a few of the larger oi? ^companies are now-producing hydrogenate! naphtha. These do contain considerable quantities of benzol and toluol. I wonder if'S" there had been any experiments made with regard to the toxicities? \te are beginning aispicion. Dr. G. Company believes jan we have the ill. as the years accurate knowiedg perhaps encourage hat probably wot. boo. MR* "GlWiMAF touid like to orfe Commercial toluol oes not contain a beizol. Benzol Frowned Upon CHAIRMAN P pass on to the next Relation to Occups DR. W ALSH: I should have mention ect will be open when we were spveaMkilnlg oUfl toxicities goif JsoOhKj EfSr' "Duirvevcltuolr voif iL_naubco.r; vents, that the medical profession irowttfEf' ptal, Milwaukee, upon the use of benzol as a solvent or d^jj: lucnt in any proportion. We just don't II %^Fatigue and 0 benzol, regardless of its percentage, fceeai_^. it is so easy to get out of hand, and chronic effects of its poisoning come on i slowly and so innocuously, they creep"oj on you before you know it. It requires rathe close observation wherever there Is am benzol or toluol. -Si NORBER1 ; n the morning I 1Iftei. of activity ; I." is state , . transient character [''derstand it and So far as the hydrogenated naphthas axS; *s<d ^ut, so far concerned, it has been said that the hydroxy "ff 114 *s that st genation does not change the chemical sti ntk which makes turc of the naphtha, and it docs not inert perform what may particularly, Its toxicity. If it is in relativd_E roodoutput- large quantities, 400 to S00 parts per millio^gjt 'U is characteriz then there is the problem of the toxicii a characterized inherent to the hydrogenated naphtha itsijj . nestigation by c But we would much prefer not to see which 1 will elai.. i: zol at all. ;A .Ia the strictest ; CHAIRMAN PAINE: Dr. Hamilton. ^ 7fost an occupation: you wish to say anything else on the 9 Jcct ? ~-. .whiic'-h can be direr ' be S S lmSUnce ir DR. H A M IL T O N : I think not. M y'`' s : s the c of the subject is four years old. t 'ho i'iT* jO '* * Bu, our perhaps very important things had come! ft >ocpt of di5tase lighf smce*"ttien. Apparently benzol is sWfj 2 " '^ r e t the > lurking danger which arises in all sr(s unexpected ways, especially as we use irom he cracked gasoline than we did before. $ ^ agree that it is something that sliul4j avoided. 1 Rate B? V d in or (A 1 h4al<h TS.,* by circum We always advise the ub=titut*" ^ defi toluol, when possible, for benzol, but 1 -1* affj: lch' unr think any industrial physician would t* lug to give a clean bill of health to - ''Sf'i'z`jgS AdoL-tCnjU!tdhn.' * *TT, Occupational Dixcaac 169 'l' "t v . ,cri' much liic length. nucrj. by, they w et ncrs Mij. her h1Vt bcginnhiii !0 11l10,! '* " morc " .i ln |j r Gammon of the du Pont ^ v ' believes it is much morc harmful Compan- bought hitherto. I hope he ' " t|ic years go on. accumulate morc , ru ^rlic knowledge about it so that \vc may ' * ^ ! s encourage its disuse, also. I think --t probably would be in the right dircc- l'c diluents large oil '" 'UR- GUMMAR (Barrett Company) : I lrogenjij !d like to offer one minor observation. onsiderabk wonder ij made with :SmmerciaI toluol, as sold in this country, W<fces not contain any measurable amount of benzol. pvW' CHAlRMAN PA IX E : We will have to vim on to the next subject: "Fatigue and Its ''^Relation to Occupational Disease." This sub- mentioned, ties ot sol- on frowns V-iefl w;n be opened by Dr. Herbert Enzer, '--Director of Laboratories. Mount Sinai HosJjtil, Milwaukee. ent or 4 -, t don't lit t, because ' id, and the come on _ creep qp v_- Fatigue and Occupational Disease Am. ,' -'DR. NORBERT EXZER: At ten-thirty the morning I generally have a very low i'?lerel of activity and suffer from fatigue. tires rather jpaiigne is a state of bodily ill health, ot ere is' any' ^transient character. It is evanescent, as we y ed erstand it and as the term is commonly tapl art th- jroy nical strucnot increase, :n relatively >Bsed but, so far as industry is concerned, -.\jfuigue is that state of the individual at 'work which makes It impossible for him to perform what may lie considered an average (cod output. per million e toxicincs ditha itselfto see ben- It is characterized by certain symptom'. It n characterized under ideal conditions ot mvestigation by certain objective findings which I will elaborate in a moment. million, d'l in the subt My study I thought -ritution but I d' >uld be 'Sib il to tiuli la the strictest sense of the term, I sup use an occupational disease is that condition which can be directly traced to some agent circumstance in employment which can lateled as the causative factor of the disn s t But as our horizon widens and our concept of disease becomes broader, and as we interpret the word "disease" as it was onginally used in the Greek sense, a state of Ration from health, or dis-ease, then we ~--'t regard an occupational disease as any 01 'll health which lias been contribCal to bv circumstances of employment. L'nder that definition there is hardiv a c ? which, under some imaginable state ^affairs, couldn't be related to what the - is doing. Those arc the two extreme definitions of tiic term "occupational dis ease." .Vow, any disease will produce fatigue. It is almost synonymous that disease limits the output or the capacity for work of the in dividual who lias been affected. What we must recognize today is that fatigue may also constitute a state of disease. In other words, that we recognize fatigue as a func tional disorder which must be treated, which must be recognized and corrected, and its causes eliminated. Tile mechanism of fatigue is grounded in a very complex explanation which is not yet clear, and prohably won't be clarified until a great deal of investigative work has been done. But in tlte past few years a con siderable amount of investigation has been done, most notably at the Harvard School of Industrial Hygiene under Dr. D ill; and in Europe, up to recent times, a great deal of work has been done, particularly in Ger many and latterly in Russia; the object be ing, in the European investigations, to find out what circumstances of employment con tributed to fatigue, to correct those cir cumstances of employment to prevent fa tigue and, hence, to increase the output of the individual in terms of his occupation, without sacrificing any quality oi his health. How, the thing that we lack at present, so far as its applicability to the practice of industrial medicine is concerned, is a yard stick of fatigue. A number of investigations arc going on in that direction, and I think before long something will come of it. Broadly speaking, two main channels of investigation are being carried on. One is a state of fatigue relative to the muscular capacity of the individual. In other words, we relate muscle strength to the load. The other is a form ot_fatigue which I think is going to be more important as time goes on, and is related to the nervous system. That arises out of the fact that fatigue is pro duced by agencies Which impair the ability ot the brain to send impulses to the peripheral muscles so that work may he performed. Xow, monotony of work may he the greatest contributor to fatigue. I use that as an -lustration. For example, we found out, in one small investigation, that jnijj,viduals cmr.ioyed at work which called for dexterity and r.imblencss and a high degree of mental alertness fatigued in less than a twenty- + ,S ^ w -3 1 !`f -j) tth in 170 29th National Safety Congress four-hour period. In other words, if a cer tain standard of measurement was applied in the morning before work began, the same standard applied at the end of the day, we could demonstrate in almost all individuals so tested that they had experienced fatigue, and that that experience was definitely re lated to the ability of their nervous system to regulate their muscular activity in co ordination. Now, in jobs which call for a stationaryposition, manipulation of instruments, or monotony of exercise, that kind of fatigue must be recognized by the industrial physi cian. The occupational disease, conversely, may produce a fatigue which may not be recog nized unless the individuals are subjected to critical examination. For example, we have noted that individuals with a mild type of hypertension, increased blood pressure, have in many instances a lower fatigue threshold than individuals whose blood pressures are normal. Or an enlarged heart, due to valvu lar disease, a leaky valve, will produce the same phenomenon; or individuals with dia betes or individuals that have a low basal metabolic rate, because of a thyroid gland disturbance, or individuals who are ab normally obese will all show variations in their fatigue thresholds. The only way that aspect of the subject can properly be investigated is to approach it from the medical point of view first. E x amination of the individual becomes the im portant thing. It is important to apply crit ical standards of evaluation, then to attempt to correct them by medical program. The industrial factor of fatigue, which I mentioned first, calls for a recognition that certain kinds of work can produce fatigue, and then to apply methods which will relieve i t I want to illustrate just two: If we recognize that a certain occupation produces fatigue, we have discovered things which will relieve the fatigue. A man whose job calls for standing at a bench, in more or less one position, doing the same job over and over again, will have fatigue which can be relieved if he can periodically sit down, because his oxygen consumption in the sitting position is greatly reduced over the standing position, and he performs vir tually less work within himself. Conse quently he has available greater reserves of energy for his performance. It has been pointed out, and we have beg,'' able to show in some small investigation, that if it could be arranged that this could be done in the sitting position, the' output would be increased and the individ.. ual would suffer less fatigue. It has been shown that, in jobs which? call for a to-and-fro movement bet-cot`? more or less fixed positions, without much?' opportunity to rest, if the period is broke#!/ hourly o r-a t hour and' one-half intervals,' and simple freedom of motion allowed toi get out of the range of what he was doing,rest is instituted and fatigue is relieved. V-. We have been able to show that the appl3 cation of bathing, in certain kinds of indus-i;! tries, will produce a diminution of fatigue and raise the capacity of the individual, to' resist his industry or his job. Those art some of the features of the occupational/ aspects of disease, or the industrial aspect"-, of fatigue, rather. With that casual introqj duction we can go on and attempt to answer*; some questions. T ests of Fatigue "Sp CHAIRMAN PA IN E: Are there ayf. questions from the floor? This is an inter;; csting subject. DR. W A LSH : I should like to ask ar question in relation to various tests of fa- - tigue. The psychologists have all had peopk putting round pegs in square holes and an that sort of thing, rapidity of processThat is one method that is not my conapt of the way to measure fatigue, but it bring, up one point; namely, the relation of fatsf* ; to the mental status of the Individt Again, the psychological yardstick ma)' applied. What is the relationship of tni in telligence quotient of the individual to tigue? Does the person using his n"n . his work fatigue more readily than one ing physical activity in which no mental ^ iort is required? k- DR. EN Z E R : If I may restate the'I'g' ; tion, I think Dr. Walsh really watt* 0 # j out whether individuals of low I.Q-i s; ; speak, experience the same plienomen ^ j fatigue under the same circumstances ^ individual of high I.Q. 'Ti DR. W A L S H ; That is right. DR. EN ZER: I would say he io though that is not generally rccogm* ^ BEN JOHANEK (Conr \Vakefield, Mich.) : Do you this is caused through ir DR. ENZER: We are chat nutrition plays an in Krvous fatigue because we certain elements in food tit |pr the integrity of the cen'tco. But we have been able preliminary experiments anc . veys that, in a genera! way, apt in an extreme instance, but in acute instances it is. ; by that? An individual vl prived of food for longer mally accustomed, in othe meals are separated by too time, fatigue will be produ that on ourselves. We too' early morning until late at . able to show increasing fatic We were also able to si --well known, of course--tiia tain kinds of food which v porary relief from fatigue, , sugars, carbohydrates, and been done on the proteins o tense that I have tried to this morning, diet is a fact, cause it becomes a disease tase state induces fatigue, t a state of fatigue if we 1 disturbance in the habits of < F actor of No WSS MARY LOU S< .Sasram & Louisville ,0 now the effect of to iatiguo. DR. ENZER: Noise is a "e demonstrated that objc We way in a laboratory, ' tested individuals for *-mtnon rate which, as I it, "*** iine. Afterwards <ar with a sound of Z* rlhy,hm and rate, the w, /"'/h er we could fatig /am and in that way m-tjCj. center of the brain . Struct one center fr to H^[Und that this inve: ' ^l i td thrreae(,hCprer!hmaCprsC. S( 'institutionally, ,,div Occupalional /ULvu.iv 17! fO H A N E K (Connor Lumber Co., 0^ M !his ** "'n, tk "0 indivi '- u ; Wield, M idi.): Do you not think a lot s caused through improper food? - DR- ENZER: Wc are now recognizing nutrition plnys an important part in S ero u s la`uc because we know there are iobs whid m bet^ `ht mud d Is broke, !f interval, allows to ' W1s dolt, relieved. at tiie appi;. ds of indoj. n of fatigue individual to Those a*' occupational ustrial jjpej casual iptronpt to answer m %'wtaiii elements in food that are important iSSo?T" .uhe. :i,,ntevgritvy of the central nervous syvs'vLin- But we have been able to show in somi ^preliminary experiments and from some sur : 4 ji that, in a general way,-food intake, cx c - .( ^ an extreme instance, is not important, Ibat in acute instances it is. What do I mean .... w that? An individual who has been de- i food for longer than he is norrBaily accustomed, in other words, .if his ~WaJs ar* separated by too long a period of <45*- fati^ c Wl!! ^ produced. We showed .that on ourselves. We took no food from ^__Hy morning until late at- night and were ^ble"to show increasing fatigue. We were also able to show--and this is jSSell known, of course--that there are cer?Mla>n kinds of food which give some tern- relief from atigue most notably the f'i-jiiuvgma*r*s, carbohydrates, aarnt/d1 a-a cgrroo<vdl ademall hnnas , j y fibbeen done on the proteins of diet. But in tiie re th ere .ratafyv Sense that I have tried to lay the subject :s is a n inter*' jiis morning, diet is a factor in fatigue be- & a use it becomes a disease state, and a dis- .TgSse state induces fatigue. Diet will produce like to ask a Vsjfji'state of fatigue if we have some acute us of fa ^disturbance in the habits of diet. sh . people holes and all ' of processes, Factor of Noise lot my concept * $ M IS S MARY LOU SCOTT (Jos. E. e, but it brings 2 ..Seagram & Son, Louisville, K v .): I would stion of fatigue ..Eke to know the effect of factory noise in the individual ...regard to fatigue. rdstick may be iship of the in DR. EXZER: Noise is a factor in fatigue. dividual to Ja We demonstrated mat objectively in a sci ng his mind in i entific way in a laboratory, in this manner: iy than one do- We tested individuals for the flicker phe- n no mental ef- .- nomenon rate which, as I said, constitutes our base line. Afterwards, we stimulated -estate the quesliy wants to find low I.Q, so to phenomenon o! rumstances as an , :;;<beir ear with a sound of a -regular"intefi-' .V-.I" 3', rhythm and rate, the object being to . whether we could fatigue one center of the brain and in that way effect fatigue in ,, soother center of the brain, or whether we could distract one center from tiie other. right. say he does, aJ> recognized. We found that this investigation brought 10 light two rather interesting things, or I would say three, perhaps. One is that there *nt, constitutionally, individuals who arc sensitive to sound, because we could pickout from a group of individuals people whose dicker phenomenon was greatly de pressed when their ears were stimulated ; which suggests, perhaps, that such individ uals work best in a quiet atmosphere. That is a speculation. Another type of individual constitutionally wasn't affected at all. His flicker phenom enon was exactly the same rate. The third individual had his flicker phe nomenon raised ; in ofher words, he was stimulated by sound. I think casual exam ination amongst yourselves will probably bring to light illustrations of the individual who can concentrate on reading a book while tf,c radi0 s going on and understand both of thenj perfccllj. sattUisfa*ctorily. Now, when we fatigued these individuals by their routine work--in other words, we conducted the same test in the morning and got a certain base line value; then they did their day's work, and we tested them at the end of the day_ we {ound that fatigue ac. centuated the direction of their namra! con. sti.tut.ion. al tend,ency. I-n oth, er word.s, .th.e individual to whom stimulation of the ear depressed the flicker phenomenon found that depression increased at tiie end of a day's work. PAUL M. HARRIS (Western Austin Co., Aurora, 111.): Does the human system have the ability in any way to build re sistance to this monotony, so it doesn't affect fatigue other than the infusion of glucose or the increasing of the oxygenation ? DR. ENZER: That is a phenomenon known as adaptation in a physiological sense and, in the social sense, it is a question of getting used to your job; but the unfor tunate part about getting used to your job is you are not the same today as you were five years ago. In other words, the individ ual today can't get used to the things he was used to five years ago. Age is an important factor in that direction. The longer the in dividual is at a fatigue-producing job, sooner or later there will come a time when his fatigue becomes manifest. We have found that our so-called fatigue testing standards showed no important fac tors, so far as age was concerned; but the older individuals had a lower threshold to the thing that produced the fatigue than the younger individuals. In other words, it is :'U&.s' ;!$ :n'* '! tf wm rlilfJU r' f lit - iM# m i:v IP Z g& szm if : '' 'V.?'V;**'* iV am . m s  ; - j tm \/ 29th National S a fe ty Congress not entirely true that experience with a job is a guarantee against iatigue. CHAIRMAN PAINE: In order that you may not be fatigued. I am going to change the subject. I am asking Dr. Belknap to take the two next subjects, 3 and 4: "The Toxic Limits of Common Solvents" and "Lead in Industrial Processes." and dwell on those subjects as one. Toxic Limits of Solvents DR. ELSTON L. BELKNAP": Mr. Chairman, I know there may be several dis tinguished guests but I am sure that we in the medical profession always feel peculiarly honored when Dr. Hamilton is in the audi ence. If there has been anyone who has been responsible for bringing to the atten tion of American industry and the medical profession the importance of toxicology in industry, I think it is Dr. Hamilton. I will emphasize a few of the .toxic limits of the common solvents, so-called thresholds. While these limits have been more or less agreed upon by. authorities in this field, par ticularly such as Doctors Drinker, Haggard and Hamilton, there is no threshold that is arbitrarily perfect, and the actual decision of whether or not the solvent has been toxic is the observation of the patient who has been exposed to that solvent, by a physician who must determine whether or not there has been a temporary intoxication and whether or not there has been a residual. Dr. Walsh has really very ably covered the subject of the hazards of spray paint ing, and solvents which are the chief hazards of spray painting, but I will mention a few which I have grouped in increasing order of toxicity. As an example c: probably the least toxic solvent--I say lea;: toxic because no solvent is not potentially toxic; in fact, some go so far as to say that all good solvents are toxic --there is gasoline. It has been stated that 1,000 parts per million is a safe limit for continued exposure. The matter of contam ination hy other substances such as benzol in 5 to 10 per cent in certain gasolines, cer tainly would alter that safe threshold. 'The next group of solvents which arcslightly more toxic, are the amyl and butyl acetates and ether which are allowable in 100 parts per million. Some authorities still state that they belong in Ilie 1,000-part-pcr- million class.'The most recent report classes them as 400. -j. The third group of 200 parts per million, ^ include the following; Methanol or wood . alcohol which, as you know, may have a l- serious effect on vision and cause blindness;--? toluol and xylol, tetrachlorethylene, tri-N, chlorethylene and turpentine. The fourth group, which has dropped to^i 100 parts per million, include carbon teiraf^, chloride and.ethylene dichloride. Then the fifth group of 73 parts per mibiS lion, benzene and dichlorbenzene; and finally *' nitrobenzene, which we, fortunately, acts-';? I? ally use very per million. rarely as a solvent, is 5 parts jSg I think it is these solvents, iifmipnorstuafnfitciteontrecmonecmenbetrrattihoantj^S}' -' may kill. This is in contradiction to the.".-' anyone in the factory. \V profession have always fe! put our cards on the table, is a great deal simpler to i axiom and tell the truth, i for instance, the benzol cor on its barrels, the word "I n a position to know whet fes did that because they ! know they do it. I think there are many that should put the same lal acts. In this connection I -, of a case that I was asked young boy, in the middle working in a shop which m daily became very sick, had was dizzy, and had to stoworking with a substance u other subject that I have been given, whichi? as harmless. is lead, which very rarely kills. These soI~; vents kill, first of all, by simple suffocatioasw if they are used in an enclosed space, 'suafiSl as in a vat. But the sinister element of thSsi solvent, of tiie toxic solvent, is the fact When I first heard of tl: I would want to see the pre plant and get my iniotr rather than attempt to talk by telephone.- (The medical whole is learning that it ca ^responsibility by demamlir Ww all about the exposur of fatty tissue or lipoid tissue, so the neryj? tliat come into their hands.) ous system is very easily affected. We involvement, therefore, of the eye, one cbgl . When I went into the si: the most highly developed nervous duciyii this worker was using a la lures. Then we have central nervous systo^U dipping it into a large bowl involvement, paralysis, inability to waft^N he then slapped on the m Also, we must realize that some of these^ grease off. On this panic; solvents actually damage the liver and evolved the idea of settin kidney, causing an acute Bright's disease. ordinarily, perhaps, blew t is thought that some of them may from him, directly opposi cirrhosis of the liver. rMtj ... material and blew the fume Fortunately, one of the best ioiven'-S fx*. Hesgct cooled, and ti one of the most dangerouUs3 is 1not incTM . Qm'i*sI***a--<skied thev *fowrt efimliaalni wi in the list at all now, the tctracldoreth>k*^j. ^ he said he riidn group used in the airplane industry i-n t w*a*s stoock material, petit past. Tliat had the peculiar ability to z1.'2 , as he knew. I said, "Well, Cw' ^ w- 14 every part in the body, including the now what it is." So there muscle. That, too, is said to be a coma-Tif opening of routine. We iuant of some of our other solvents. L into a shed in the yard, c been mentioned that possibly the foitnjj^ *0 finally got a flashlight, contnmin.incc in tnchlorahylcne "~*s ^ stvel of benzol marked "1 tile reason why trichlorcthylcne had 0 Nov ,n ne in that shop titally had a rather bad name. I ?: e*n<**doi,lng. Then were a d< I think one o.f the most i m p o r:ttbWa *n t -y ib0l? cl\ _ same to rcmember in dealing with the a good solvent is that we arc dcalii'S ' f fan." had not ff0,,en t potentially dangerous substance make any effort to conceal t/iat ' .^wSThat a"oul y N v i^ i:v:yta t m "other i$ r , Ui i'U['lltitillili ! )l'.\VU.\Y ! 73 report classas rts per million, lanol or wood may have j ausc blindness' methylene, trh lias dropped to e carbon ttra de. 5 parts per milcne ; and finally .-ornately, actuvent, is 5 pans remember that t concentration, adiction to the en given, which tills. These solipie suffocation, ised space, such element of the is the fact that s system because, are ' ilvents, -rge. .ade up ,e, so the nenffectcd. We have the eye, one o: nervous strucnervous system biiity to wait some of these :c liver and the ight's disease. 1; hem may cause ,est solvents arJ is not included jtrachlorethyleoe industry in *fi ability to attack ludine the he^ to be a containsolvents. It hai ;bly the ion'' ylcne was rea ' ,ylcne had on?- important tlii?!' I, the control re dealing 'il stance and I that fact ' r'-" ,c j,, the factory. We of the medical .Profession have always felt that we like to - f ( our cards on the table. We know that it srtat deal simpler to follow the ancient ' -ttiom and tell the truth. So that I admire, for instance, the benzol company which puts li on its barrels, the word "Poison." I am not . j position to know whether they more o- y gs did that because they were told to, but ' I know they do it. more than thirty feet away, they were doing spray painting, and they were doing it prop erly. Instead of exhausting the spray over head and bringing it right back in the worker's nose, they had their suction under neath the objects to be sprayed and took advantage of draft as well as suction. They had good engineering equipment and staff, but they simply didn't know what they were using in this particular instance. iyul dunk there are many other companies i'vthat should put the same label on their prod- In this connection I would like to tell %[ a case that I was asked to sec, wltcre a i -joung boy, in the middle of the summer, 'Yrorkme in a shop which made motors, sudr-daily became very sick, had severe headache, -?*as dizzy, and had to stop work. He was .i&rorking with a substance which he regarded harmless. '.'^5When I first heard of the case I insisted 'tl would want to see the process and see the jiiphfflt and get my information firsthand ^lather than attempt to talk to some foreman .'*hjr telephone. (The medical profession as a .Vhole is learning that it can only fulfill its .^responsibility by demanding the right to ;!,know all about the exposure of die patients ...'fiat come into their hands.) When I went into the shop I found that this worker was using a large paint brush, : dipping it into a large bowl of liquid, which he then slapped on the motor to get the rease off. On this particular hot day lie evolved the idea of setting a fan,, whicli ordinarily, perhaps, blew the fumes away from him, directly opposite the bowl of ttaterial and blew the fumes directly in his ue. He got cooled, and then he got sick. .h i asked the foreman what was in that '..oaterial, and he said he didn't know exactly; stock material, perfectly safe, as far ' ** ^ knew. I said, "Well, I would like to *oow what it is." So there was considerable Psetting of routine. We finally went out #t0 a shed in the yard, completely dark; finally got a flashlight, and we found a *?rrel ot benzol marked "Poison." no one in that shop knew what they 'eve doing. There were a dozen other work- fortiuenaacthelyd,ohinagd tlic same not gotten thing but who. this brilliant idea of the fan' I had another experience with a man who was a so-called neurotic I think most of you can spot the neurotic if you have had any shop experience This man certainly was. He had been to half a dozen doctors. One told iiim he was going to die, and another one said there was nothing the matter with him. Again I demanded to sec the shop. We found he was spraying an aluminum paint with a harmless solvent, a diluent, with good suction and a good spray gun. How ever, on further talking with him and con firmation from the foreman, I found he was tlic one man in the shop who was delegated to clean the spray guns at tlic end of the working day. He would sit down and squirt material, which he called chloride, in and out of tlic spray guns, and lean over the vat he was working with. Finally, he noticed he began to get happy and whistle and sing, and he began to look forward to the experi ence at tlic end of every day. However, finally he noticed he was getting weak, he was dragging one leg, and his heart was going very fast. Well, this illustraics one other sample. This was a large corporation. Yes. they were using chloride. Finally, after great difficulty and having to go to the treasurer of the organization and going into the files we found that this was a material which they had bought from a supply house in another city, and they did not know what was in it. We finally found out it was ethylene dicnioride. The course of that individual is interest ing, in that we put him in the hospital. It eventually cost that company quite a lot of money. I was in this to find out all I could learn"aobuf "the" action*o'f that particular substance. I put the man in the hospital three or four weeks and did a number of delicate tests on him. nc curimi* tiling about this particular Welt, lie came through, and interestingly was that in another department, not v.c found that lie had an opportunity to dc- :|l m' i i l i -m K.-i 174 29lh Xational S a jc ty Congress velop a cold once or twice. Every time lie did, he developed jaundice. Then, of course, we did liver function tests and found reduc tion of that. We found he had a weakening of the heart muscle. We found a definite loss of tiie reflex in one ankie-joint, showing a definite involvement of the central nervous system. We were able to get all the physicians to agree that this man was considerably dis abled, that it was due to his occupation. You will understand, l was seeing him not for himself but for the company. I think a good many of them thought I had been a little generous to this malingerer. This man went ahead and got a large settlement. I don't know anything further about the case except that I did hear that the man died and that the death certificate said "cirrhosis of the liver and heart failure." L'nfortunately, we didn't have an autopsy to confirm it. In my opinion, the toxic solvent is one of the most dangerous substances and it may seriously disable and kill. Lead in Industry As a preface to the subject of lead in in dustry I would like to say that I am not specializing entirely in industrial medicine. I am one of that increasing group who feel that industrial medicine is not a specialty in itself but is merely a division of internal medicine or diagnosis, the large field of medicine which in private practice corre sponds to or is correlated with the field of general surgery. I am glad that a large pro portion of my practice is still private prac tice. I am also consulting medical director to one of our industrial concerns in Mil waukee. with branches over the country, so that I have an opportunity to see lead and other toxic materials. When you sec a man who has said, "I have lead poisoning," do not forget lie may have some other disabilities and diseases, such as acute appendicitis, gallbladder, kid ney colic and so forth. In my private prac tice my intcresfhas hce.'t'aiia'rpcmrd so-that I always make an effort take a very care ful occupational history eti a patient, even though he may come to me purely as a heart case, lung case or what-havc-vou. In this particular plartt in Milwaukee, which began by having and still has, as a large proportion of its w-.rk, storage battery plants, when I came there about tun ,.Wr ago wc were having an incidence of jboo24 lead cases per 100 employees per yQr' which corresponds pretty well with the pe7' centagc oi la to 10 reported by the Publie Health Service in work about that time. In five years, by cooperation with the medical department, the engineering department and management, we dropped that to an incidence of 2 per 100, and for the past five years we have had no cases of lead poisoning at all. Wc arc still handling and we are still handling it in large amounts. I think that in the storage battery indm- try, probably, men arc exposed potentially at least, to the greatest concentration of lead for absorption directly into their bodies thaa in any other industry. 1 am glad to repon that, having followed this particular group of workers of about SO for this period, it 111e end of ten years they are certainly just as healthy and, in many respects, I think: healthier than the general run ot the popu-1 lation. Of course, we have reduced their' lead absorption, but at times it will breaky down the physical resistance and respiratorrv protection. They occasionally have larger doses of lead, hinny of these workers were persons who had had lead poisoning or sen- ous lead absorption in the period of oirj servation. 'ij. Lead is one of the- most widely used socalled poisons in w-cll over 200 industries., I think there is no doubt but in the large' industry the hazard is well controlled. First of all, it is recognized and then every effort is given. N'o expense is spared to study the men and to reduce the continuance of ast_ exposure. However, in the -mall industry,., which is the major portion of industry this country, lead is continually cropping uf* and even silicosis, which got the cutltr^ the stage in recent years, certainly in y 1j cousin, has now taken a back -`tep, and *a has come back into its own. together w ^ the ever increasing use of solvents. I would like to stress again the datig^ here is one of non-recognition, that we > our trouble in the small plant, not in large plant. I will rapidly run tliroug . types of industry where I have >cefl poisoning occur and in which it is an portant factor. The most important is the storage h a ^ ( industry. Then the streamlining oi "f 0j mobiles and trucks where, after wcM courte. as first smoot ( cooled, grinder a: finely divii the fact t: iny lead i Remember more dan very rare through t! ception of organic ar It is ra smaller p give up rr 1 Here is a horse-and; Is hand fv ire heavy The prob by machir It has ; ing was i perience i :. it is very ' where lea - substance; forth, wb however, because i stand the Occupational Disease 175 ursc, as many of you know, they were at 1 about -r year, ll'e Per. Public lime. smoothed off by lead paste which, after "cooled, was then ground by machine Linder and produced a great amount of f^jy divided, inhalable dust. This brings up (j,e fact that the most important hazard in v lead industry is the point of inhalation. ith tiH. Remember that lead dust inhaled is much departth u tc, more dangerous than swallowed, and that " rtry rarely are lead compounds absorbed ihe Pli, of leai ' through the skin, perhaps with the one exj. ttptjon of tetrachloride fluid which is an mg lead, - organic and fat soluble substance. imounts, L It >s rather amusing that many plants, v indus- l.";smaller plants, particularly, have had to '.entially, v--giw up machine grinding of welded joints. t of lead fits* is a return of modem industry to the lies than ifeborse-and-buggy stage. They are going back o report *ito hand filing where, of course, the particles tr gTOup heavy and are too large to be inhaled. eriod, at "fThe problem can be licked, however, even inly just I thmi te popp ed their ill break ipiratory ,-e larp ers .wot' ; or sen- d of ob- 3 yiy machine grinding, if one uses respirators. W i t has always been said that lead poisonLg was very common in painting. My ex perience in ordinary painting nowadays is ^ i t is very rare, particularly on inside painting ^w here lead has been substituted by other lances, such as titanium, zinc and so forth, which are harmless. On the outside, iowever, lead is still used, in many instances, because it is the one substance that will USttl*"' \ -dus e U.,,. ..ed. Frit -ry eSort tudy the _ of any industry', lustry 1 .ping u?: enter of the weather. fere we come again to the question of ^-jiaidy divided, inhalable dust where men 3g/born off old paint in private homes; not in ^rijthe large installations, of course, or sand, 'i Mother by machine sanding or by hand sand- There we have the question of finely divided dust which is inhaled. You must .remember that dust when inhaled passes dikr, redly into the system and immediately cir.cnlaies throughout the entire body. in Vi>>' Intake a recommendation, therefore, that and lo iter -ith worker that has gotten his lead by bum* or sanding, be given a respirator for t purpose, even though he is an outside dang*' 'e-worker. we hs't it in die ought reen lead ; an in- to* wrecking of old buildings and old r L j ^ course, there is the constant pres-f** I lead absorption when the steel has ; - f S , coate<^ with several coats. It ideally lume which is so fine as to be al- invisible and is absorbed directly into e batirrf iur W . Min?. v <oinS5'S|!e m ' "^ ,c o n ^ ' v ,a ' t *i a t a v'' r k e r t Pcta?iontoa>ts ctaon urseeallaynpraoirt-elcint ehimressepliir,ationr.myI have seen a great many men in one particu lar type oi ship industry, cutting up old ships outdoors in mid-winter, and I have never seen men leaded up so rapidly. Of course, this is an old story. The Navy found this out twenty years ago when they scrapped many of the old ships. Unfortu nately, some people in industry, as well as doctors, arc not very good on keeping up on their own work, by reading, and experi ments have to be made again. In the smelting of lead or zinc ore and scrap metal, lead poisoning occurs. In pot tery making where a glazed mixer is used, one most usually is exposed to lead. In the printing industry we have heard a great deal of lead poisoning. I had an opportunity recently to make a survey of a group of printers with the W is consin Industrial Hygiene Unit They went into an analysis of the air, and I examined the men. To be sure, our list was not large, some 30 men in fourteen different printing establishments, but it was striking that all of these men were in excellent health and, as far as I could see, there had been no great deal of turnover. However, there are one or two spots in the printing industry that are danger spots: that is, of course, the man who remeits the old type metal or who saws it, if he uses a machine saw. I think it is interesting, going through our records of printers in the State of Wisconsin, for a great number of years past, we have had only three cases, one of which was really a serious case, and that man was one who rcmeltcd--he was the for gotten man, worked down in the basement on a kettle, where nobody paid any atten tion to him, and there was no protection. In passing, I will simply name soldering, and that occurs very frequently even in the evaporated milk industry out in the country; tempering of metals, brass foundries, ink making, insecticides. This potentially may occur in leaded steel when it is scrapped. Then I would class as the final one, the risk which says they have no lead hazard. That is the place you should look particu larly. As I said, the important portal of entry is through the nose. If we bear that in mind, the problem of control of lead poisoning is really not difficult. If, of course, your en.giacciS--reduce- ihe-exposure to 1.5 milli gram?, I don't think you will have a case of r:; f i*l fi !.,>.!: ' ! 17a -9lh Xational Safely Cant, lead pui-miing. H ow utr, ;k .1 matter of practica! interest. I think it if ven' difficult to eel ttere tit ordinary industry, and I would more or less formulate 3 as a safe level. I think it has also been found by other workers. However, if you jet over 3 you certainly have the possibility of serious lead absorption. 1 want to emphasize that mere lead ab sorption does not mean the man has lead poisoning. He may have a lead line, may have lead in the urine, .08 milligrams per liter, Imt that does not make lead poisonin':. That is merely evidence of absorption. He must have, in addition, clinical symptoms of one of the three types of lead absorption. As a lira! word in regard to the role of the medical profession in its cooperation in industry, it seems to me that the medical man should first of all be responsible to the highest man in authority in the plant, so that he can go direct to him with any prob lems that arise, and before any new pro cedure is used or any new chemical, have a conference with the physician to see whether there is any possible danger, whether there arc volatile solvents or lead, so that the danger to the men may he prevented before it happens. I am not making a pica for absolute sub stitution for and avoidance of the use of lead. I think industry cannot get along with out the use of lead, cannot get along without the use of a number of these solvents; but if industry is forewarned, and if the worker is infonned correctly so he will cooperate in the use of protective devices and. finally, the medical profession is allowed to see the pa tient as often as they see fit, perhaps every two or three weeks, then there need occur no occupational disease in industry. CHAIRMAN" PA IN E; Are there any questions on either one of these subjects that you would like to ask? MR. HUTTER: What is the effect of the smell of kerosene on the worker? Is that a permanent effect or just temporary? DR. BELKNAP: AS far as I know, there "is no ill effect ii-orn the*inhalation of kero sene. R. S, SKYRM (Employers Liability As surance Corporation, Boston): Would Dr. Belknap recommend the direct venting of lead pots on linotype machines where the pots are electrically heated and thermo- statically controlled so the temperature the lead doc- not exceed 300 degrees? ' DR. B ELK N A P: That is a good prj(. deal question. As we know, lead melts at much lower temperature when volatility In my experience, lead does not really volatilize until around 1,000 or 1,100 degrees In this group of workers that I am f0|. lowing, some s ears ago, large lead pots, tWo or three feet in diameter, were unhooded be. cause ot certain changes in technical pro. ccdure, anti tltc plant never got around to the hood. I disapproved of that and re- ' pcatcdlv said they would have cases of lead poisoning there if they didn't hood. They said they would just as soon as it was prac- tical. It has never been practicable, and I am here to say we have had no lead cases develop to the point of disability, and we 1 have bad very little lead absorption result from that. The same men have worked there . for ten years, dipping lead out of the pot,-' incidentally, at temperatures ranging usually k from 850 to 950 degrees. In this group of", linotype workers we found no evidence of'3 lead absorption in some of the shops where?, they had no suction. I would not say in 073 I tliiuk probably limits. MR. GUMMA! pletely the princip 0{ safety standarc should be based c toluene, there hav osed in the bet; painting came into air as fine mist, orates at a slowe inhale the mist, y is toxic, . [ have employer State, New fersc trho for the past any reported case; ing; yet Ohio in had over 69 castline in the petroiei As to the expe: no experimental < should be such a confusion arises : lingnish between v'.'tng. It is a fact t own experience that hooding is necessary at- 500 degrees. .Ajj MR. CARR: 1 wonder if there is any evidence to indicate the toxic limit for butyl alcohol could he raised above that given?, We had experience over .mne twenty yean jF with the same group of men, working concentrations from 200 to -100 parts per? million, and under careful examination they^ have shown no indication of trouble. * One other question is whether much work*has f>ccn done on toxic limits of dioxene? X rations, toluc ' toxic than benzol chamber where t million, you wou (torn toluene am ; with benzene, but . phenomenon iron mg. CHAIRMAN 'II he "Skin A landlcrf bv Dr. M DR. BELKNAP: I think Dr. HaimKoaJ will have ro state if site recalls whether we ^ have toxic limits established for dioxene. j: DR. HAMILTON: Dioxene is the trade'j- name for diethylcne chloride. No toxic litwj has been established for that. We considered _ it a fairly 'ate solvent until some very dm astrous cases occurred in England if0, over-expe-ure, causing five deaths. ->ii then we have looked upon it with a 2 . deal more suspicion. There has not enough work done on it to establish ^ maximum allowable concentrations. e DR. BELKNAP: In regard to butyl l1' cohoi, the butyl radical acetate is luch 1? 5 toxic than ethyl or methyl, particularly*^ 1 would be interested in your point ot if. J. 10 what exte " ?d to in mtants and t " not surprisi re a m Ll',(td States "*tw Pir di;ea I?,"'.OOOwo, * 5"r, that SUl1 of 'Ilei a"i^:nOirnys, I Occupational Disease 177 temperature 0i ' degrees? is a good prat, lead melts at a lien volatilized not really vola. 1,100 degrees, that I am fo|. ,'c lead pots, two re unhooded be lt technical pror got around to >f that and re ive cases of lead 1n't hood. They n as it was prac-acticablc, and I ad no lead cases inability, and we absorption result ave worked there i out of the pot, cs ranging usually In this group of d nr 'dcnce of f th <p$ where d tto, say in my isr is necessary at if there is any ic limit for butyl iiovo that given? >tnc twenty years men. working iz n -100 parts per examination the' . of trouble, tether much work tits of dioxene? nk Dr. Hamilton .calls whether we -d for dioxene. xciic is the trade vie. No toxic limn at. We considered nl some very d:v ti England irei ve deaths. Since n it with a good re lias not beer to establish an> atm tions. card lo hnty! *' late is much lieI. particularly, o' .ur '.'int of v:y"- I ihiuk probably it could be made at safe Soiits- MR. GUMMAR: I want to endorse comfletely the principle of maximum clearances ,,( safety standards in engineering, but they jjuld be based on factual data. As regards joluene, there have been enormous quantities i<ed in the lacquer industry since spray painting came into use. It is sprayed into the air as fine mist, and even though it evap orates at a slower rate than benzol, if you inhale the mist, you get severe effects, if it is loxic. I have employers in four states. New YorkState, New Jersey, Ohio and Connecticut, who for the past sixteen years have not had any reported cases of chronic toluene poison,'bg; yet Ohio in the past sixteen years has lad over 69 cases of poisoning from gaso,llne in the petroleum industry. TvAs to the experimental results, T can find 'no experimental data indicating the toxicity should be such a low value. Some of the ' confusion arises from the failure to dis tinguish between chronic and acute poisou"bg. It is a fact that in extremely high con centrations. toluene and xylene arc more loxic than hcnzol; that is. if you go into a chamber where there arc 20,000 parts per million, you would he unconscious quicker from toluene and xylene than you would, j 'th benzene, hut that i an entirely separate 1 phenomenon from the slow chronic poison ing. CHAIRMAN P A IN E : The next topic j will be "?kin Affections" and that will be j handled he Dr. M. I. Reuter. Skin Affections DR. M. I. R E U T E R : When we consider ,0 what extent the skin of the worker - faposed to Injuries, the action of chemical truants ar.d the various infectious agents. I: ls not surprising that occupational skin di;~ eases are a major problem in industry. The | United States Public Health Service c-1:- , mjlcs 69 per cent of occupational disease- ?r{ skin dh-cSSSS. Thev carried out a stud" ' m 100,000 worker? and found, in the cour*: ! * year, that one per cent of these worker* i " Cre affected with sc-mc skin disease as ?. i Jult of their work. This did not inclu'f; iu^ns, splashes nt acids and alkalis, and the Grdinary Infection* of scratches .: :il>'a>iOTv. The problem confronting the physician is to determine the relationship between the kin disease and the occupational environ ment, to discover the nature of the offending agent and to adopt measures designed to cure the condition and prevent its occur rence. There arc many predisposing causes of occupational dermatosis, such as unclcanliness of workrooms, of clothes and of per son. Previous skin diseases as, for example, eczema, are potent factors, because individ uals with eczema react seven times more frequently to external irritants than noneczematous individuals. The skin of the young and old is more susceptible to irrita tion and infection than the skin of persons in middle life. Dry skin is more vulnerable to irritants than oily skin. The skin of certain parts of the body is especially sensitive, for instance, that of the eyelids and genitalia. Anything which lowers the normal threshold of resistance of the skin may act as a predisposing factor in the production of dermatitis and of infectious lesions. These factors include bruises, marked sweating and maceration, prolonged ex posure of the skin to water and especially to alkalis and repeated scrubbing of the skin. These agents tend to remove tin: normal protective coats of the skin, that is the outer homy layer, and thus expose the sensitive epidermal cells directly to irritating material. A point fairly recently emphasized is that individuals with common athlete's foot arc much more prone to occupational dermatitis or the hands. Apparently ihi infection of the feet acts a? a sensitizing factor. The actual causes of occupational derma toses are mechanical, physical and biologic agents and chemical irritant*. Mechanical agents produce bruises ami laceration., as well as friction and pressure resulting in various inflammations and thickening* of ihe kin. The physical agents which may produce ;tn occupational dermatosis arc heat and void, either dry or wet. electricity, ultraviolet ray, cither from the sun or artificial, and x-rays or radium. The biologic agents are the common bac teria. fungi and parasites. Tor the most part, however, occupational affections of the skin are the result r.: con tact with irritant? of a chemical av.irc. /:>' irs J9tli Xutional S a /.:v Congress usually acids or alkalis producing simple in flammation of the skin. As a subject for discussion, I might say that probably cleansing agents used by the DR. REUTER: 1 have lud very |m, occasion to pass on a question of cancer the skin arising from alleged contact some carcinogenic agent. . ., 0i industry just as dea ^ddaital injury. There are v the problem. One, o Toothing about it and that workers are one of the most potent factors in the causation of occupational dermatitis. C. T. DENSMORE fKoppcrs Co., $, Paul. Minn.): I would like to hear a'littij eighteen states in the Union a jj, not compensating occupa CHAIRMAN P A IN E : This is a subject in which there are a number of men inter ested. Will you expedite your questions? DR. E N Z E R : I would like to ask Dr. Reuter to say a work about skin cancer in occupational exposures. Skin Cancer DR. R EU T ER : Ewing has set forth five postulates which must be fulfilled before accepting trauma as the cause of given can cer. Ewing states: "First, the authenticity about the effects of coal tar and creosote oiis in relation to cancer and what-iwand also the inhalation of the creosote ^ pors. DR. REU TER: Regarding the develop!1 m.ent of cancer from coal tar and creosote,1' I have had no experience. We do know that coal tar is the nearest to the skin and does' produce an inflammation about the hair"follicles called folliculitis. It is undoubtedly5 due to the plugging of the follicles with the' tar and perhaps some stimulation of epidermal layers of the skin from the tar 5 ( ill. Out of the other stat |Cir which are compensatin jeoiJ diseases, and some of peosaung by schedule. Xow, schedules are usual! dat there are a great many at named, but very generallj tbit they leave out the one oc ose which causes the most cample, silicosis is left out o ot the state laws which h. Therefore, silicosis, which is motional disease is not comi and adequacy of injury must be estab which sets up this inflammatory reach When we go back to the p lished." That is, the patient's statement re around the hair follicles. I think the sameii of workmen's compensation, v garding injury must be substantiated, and true with creosote. But, regarding the actual5 the compensation fathers dt there must be actual tissue damage. development of hypertrophic lesions of question at the time the com "Second, the previous integrity of the skin, particularly cancer, I have had no were passed. That was the wounded part before the injury must be periencc. Either through inadvertence established. DR. BELKNAP: As for creosote, I haw; ases, through design, occupa "Third, the cancer or tumor must arise at had no actual cases brought to ray atleg woe left out of the laws pr bat'accidental injuries were : the point of injury. non. As far as I know, the fumes would'Ky sued. I think that was large no more irritating, possibly, than causing*! "Fourth, there must be a reasonable time irritative cough. I know of no cases, rtii :therather violent split from tl limit between injury and the development of the tumor." That is, if the tumor develops c: acute chronic bronchitis or other'gj* cir.ogenic results. law system and leaving out oi the qnestion of negligence. It within two or three days after the injury, uoloit split, but it is surpris it isn't reasonable that in that short a time a CHAIRMAN PA IN E : We will kajj 1 these years occupational di :: tumor could have developed. ar.y other questions to the end of the 0^ . "tain uncompensated in so mn kon and hear Mr. H. A. Nelson, Indus!!-;. "Fifth, the positive diagnosis must estab Commission of Wisconsin, on the question-/ When we consider the natu phonal disease, which is it: lish that there is an actual tumor present 'Should occupational diseases be consider5' "jtdious process, over which and the nature of the particular tumor." industrial Injuries?" ; hie employee, has no cot CHAIRMAN PA IN E : Dr. Enzer, do you want to speak to the point? Disease Vs. Injury the employer, as the **** *W you this morning, . DR. E N Z E R : I thought Dr. Reuter might say a word about the increasing attention now being given to highly complex chemical agents which have the property of inducing cancer in the experimental animal. We know of certain agents which have that property in the human. The commonly known one is tar cancer. We know also of certain aniline products which would produce cancer of the --ItSn'.^of the" urinary bladder, and so on. I think that subject is highly complex, but I think it should be brought to your attention that in the dermatology of today we deal not only with dermatitis but also deal with tumors. H. A. N E L S O N : Mr. Chairman: question which I have been assigned is ceptible of treatment in several way*- ran treat it in a highly technical way ' -nibble about the court construction o word "injury" or we can treat it |n J W. eral way and ask whether occupation* ^ rases should be compensated. That i - real crux of the question today. -f^r It sometimes astonishes me ,as ; ears after the passage of compensat* ^ .ve arc still disputing this <,l,e* ,,jiti-. nether we shall compensate a ^ which may cause disability and "l"c JP'at of control, there seer *P"" td times more reason ITT who cannot protect h .e way should be compc: "phonal disease rather tliar W injury. Oppose there is no que T? "al crux of the matter a ? ,he employer, and t , d "le so stated-accrued an accrual of dosage S T ? ' in disease, and u" the mav co ^ the employer has a lar  ' Vi*S- Occupational Disease 179 e liad very li|,jt stion of cancer of eged contact wits Koppers Co., $(_ kc to hear a little i tar and creosote .or and what-not, f the creosote va- t 0f industry just as clearly as does an 'dental injury. There arc various ways of meeting the problem. One, of course, is to ,0 nothing about it and that is what about eighteen states in the Union arc doing. They ^ not compensating occupational diseases at all- Out of the other states there are a /ew which are compensating all occupaBonal diseases, and some of them are com- , pensating by schedule. rding the develop. .1 tar and creosote, . We do know that the skin and does n about the hair . It is undoubtedly ie follicles with the stimulation of the skin from the tar, i.t.Kow, schedules are usually designed so 'that there arc a great many diseases which are named, but very generally you will find that they leave out the one occupational dis1.rase which causes the most disability. For Iexample, silicosis is left out of a great many . iof the state laws which have schedules. ``'Therefore, silicosis, which is a serious octupational disease is not compensated. ammarory reach 'IgWhen we go back to the prime principles I think the same is sSS workmen's compensation, we wonder why regarding the actual compensation fathers didn't face the ophic lesions of the question at the time the compensation acts t h 'tad no ex- fCwere passed. That was the time to do it. 'Either through inadvertence or, in some for creosote, I ha ought to my attotthe fumes would be bly, than causing an of no cases, really, tltitis or other cu 'cases, through design, occupational diseases were left out of the laws pretty generally, but accidental injuries were to be compen sated. I think that was largely because of the rather violent split from the old common law system and leaving out of consideration the question of negligence. It was a rather violent split, but it is surprising that in all ll ; Wc will lea of these years occupational diseases still re the' end of the set- main uncompensated in so many states. \. Nelson. Industrial sin, on the question' senses be constderfi When we consider the nature of an occu pational disease, which is usually a slow, "tsidious process, over which the man liirn- ^ f , the employee, has no control, but over s. Injury which the employer, as these physicians have told you this morning, has the entire Mr. Chairman: Tl* been assigned is St)- :n several ways. "j iy technical way **/ t construction of " ran :he r treat it in a occupational Sd*ji"f" ) ensated. That is n today. :-hcs nte that t!''1'' of comronsatior. *', ;g this .-gestion,/ .tpuitsate cotwl|V^ Power of control, there seems to be one nundred times more reason why the em ployee who cannot protect himself in any Possible way should be compensated for oc cupational disease rather than tor aeciden- -U1i5iC-'. ,,___ ! suppose there is no question but that . e r?al crux of the m atter is lient of cx- / 1125 to the employer, and th at conics bc- L "5 of the so stated accrued liability. H ere , 1 '"en an accrual of dosage w hich finally '/mintes ip. <1: sense, ar.d this accrual is :-ch that tin ditsiceasc mav come at ''tient. ;'.;tv i which sr'~ " the cm-, iyer lias a large nanti.1 employees who have this accrual of dosage, it may be that in periods of depression the expense to him will be rather great for the time being, and that must be met in various ways. Employers are humanitarian. Most of them would like to do these things but they are also in competition with each other, and that means there must be laws and regula tions for the compensating of occupational disease if the job is to be done in a satis factory way. Another reason that is often given is that industrial commissions and accident boards are unable to decide the question of occu pational disease, as to causation, between tltc process and the final condition which re sults in disability. I think that is a rattier fatuous objection, in view of the develop ment which has been made in medical sci ence within the last few years. I think those questions arc no more diffi cult to decide than the questions of aggra vation of pre-existing conditions which are clearly under the law, if we may ascribe them to accidents, and also to the obscure conditions which are ascribed to accidents and as to which compensation hoards and commissions have to make decisions every day. Can Stamp Out Disease Eut the most glorious thing that has been accomplished by occupational disease laws is the fact that employers have become con scious of tlie fact that they can stamp out occupational disease. I am glad to say that in Wisconsin we have practically stamped out silicosis, that in a few years more it is going to be practically a negligible thing. Dr. Belknap has shown you how lead pois oning can be almost entirely eradicated. That is the glorious thing which we have achieved through the passage of occupa tional disease lav.-', I want to give a verifew figures showing the drop in siiieosis in the State of Wisconsin since 1933 to 939. These figures arc the percentage- of com pensation which v.erc paid in sinco-i-' ease' as compared with :he total. In 1933 the lig ure was 9.4; 1934. 4.8; 1935, 7.9: then 5 and 2 and .9 per cc-nt. and. in the year ln39. i.3 per cent which figure is getting about on a level. I think there :- no (ut-.stujn hi:: ::::u the imlilie i- ieiuar.v-v that ueeut'a.v :.ai di-- Ijlll f, i!D m I x>t i;'. 1 ixn 29th Xatwinii Safety Coitm I ease be compensated. Tile trend is coming on. I believe that industry and society will be gratified when the problem lias been solved by whatever methods may he adopted and suited to the different states. CHAIRMAN' P A IN E : Are there any questions you want to ask Mr. Nelson be fore we go into the general discussion ? ADOLF AMRAM (Hamlin & Co.. New York City) : We passed a compensation law in New York State some two or three years ago. Perhaps you recall that first ate passed a most illogical law, the all-inclusive act which acted most disastrously not only to in dustry itself but to the workmen. You arc familiar with the history and the recall of that act. I dare say in a number of states it is absolutely right and proper the compen sation act should include silicosis, but it should include silicosis on a schedule basis, as I think is the case in Illinois. MR. NELSON: All states are not as fortunate as some other states. I think we arc showing generally throughout all of the states that the problem can he solved. Protection for Welders CHAIRMAN P A IN E : We have a few minutes. Anyone in the audience has the privilege of asking this panel o( doctors any questions they want to raise on these main subjects. .1. 5 . GREEN (Edgcwatcr Steel Co.. Oakmont. P a.): I would like to ask to what extent an ordinary welder in a small plant should be protected? Once in a while there will he a hardening material which has poisonous results. Other times there will be flame cutting of paint on a product which will raise some noxious poison. To what ex tent would a welder or a cutter have to be protected ? CHAIRMAN P A IN E : The question is, how arc we going to protect, and what is tlie exposure to welders on new material or on old material that has been painted? I will a=k Dr, Walsh to answer that ques'-'''"I'ion. -- DR. WALSH: Within the past couple of years wc have had occasion to go over a group oi about 1,000 welders. Of that group some .100 have been welding for ten or more years. They were gone over from the clinical point of view. X-rays of the chest were taken. Disability due to sickness over .. ten-year period was calculated and seen f ' each individual man. There certainly wSs r marked difference In sickness rates and disability rates in the welders as eompj,^ to the general run of employees working lt their side in the same plant and in the sam{ economic situation. j, bo linen; ,-ovcr> rate irm .jjvidua! who lm per cent cornu , or the mdiviii ',,trust there. Now, "lien we c solvents, sa When you are considering welders who are cutting painted materials, lead-bearing paints, or who are welding in confined spaces, you have a different problem; but tor tlte ordinary welding group, working b, a large, airy room, with ordinary precau tions and ventilation, their health is just good as any other group of workers. If thev are cutting paint or toxic coatings of anv kind or lead-bearing steel, or if they are working in a confined space, then additional respiratory protection is necessary. jje limits oi an g that the pro dvtd by a bis jtoblem, but by ,,uJysis and stu. ,,ad to tiie indi ,,y that this cs Ssfry realize tit: a t forms the h bee problems. DR. B E L K X ? y what lias a So far as the question that was rampaM a few years ago, that is the development of so-called fibrosis of the lungs due to weld-, ing, we have not found this to be the cast' Dr. Enter and Dr. Sander at Milwaukee have had occasion to examine at postmortem" a few of these individuals who have been'* wclding for long periods of time in confined i spaces, usually. They did find there was an5 increase of iron in the lung but no fibrosis:, causing harm. jat is when a caterial that h. nth lead, lie, o gaire lead absoi out as quickly my other way. It is very sin tors we have arhenever he is ise such a respi series of cases Recently, wc also have examined another ~ group of wt-Mers. that is a variant of the. welding trace, scarfcrs, in the continuous production c: steel. These scarfcrs use a" long torch and blow out the defects in the billets rather than chiseling them out. This group also, v.hile it is an infant in the group oi welders, apparently have no health ho ards of any consequence in their trade la other words. I think if ordinary precau tions, so far as ventilation and so forth art concerned, we need not lie concerned other than if wc are using lead or chromium or some of tlte toxic materials. sorption was a pairing some uuount of lead. Also, I had s dozen cases op tanks in a steel tanks hat could not und jetting lead. '. with a torch ? ibsorbed lead i difficult ques "titter of bav: the work is :o CHAIRMAN' PA IX E: Or. Enzer will speak for a minute on the subject and th1 Dr. Belknap aill follow him ripht up. DR. EXZER: I want to seize tlte oPPr' tunity to make some comments relative tiie general attitude of this panel discussk^ft is most important that in any app*"011 to the proi/tm of industrial health wC member tha: a statistical analysis of is not a true criterion ot the health of individual, in other words, just like thc 5 MR. CARR have had "'ork on gain n`tnsus fume ^ coated electro Occul'azionai Discaso 1S1 sickness over the lated and seen for -e certainly was no ness rates and in Iders as compared ployees working at nt and in the same ring welders who trials, lead-bearing lding in confined rent problem; but group, working in : ordinary precan:r health is just aof workers. If they ic coatings of any el, or if they are tcc, then additional necessary. that was rampant the development oi iungs due to weldthis to be the case, oiler ` Milwaukee mil postmortem Is w.io have bee: of time In confined d find there was as 'ms hut no fibrosis examined another a variant of tht in tile continuous ,-e scartcrs use i the defects in the ng them out. Thu in taut in the grout ave no health Haz- in their trade. Iordinary precaan and so forth are i*c concerned other ul or chromium rl~. ' : Dr. Enzer w> c subject and iher idm richt up. 10 'eilc.thC-QSS!' mim-ms relative :s pniici discus10'; t in any approa:rial health we <' aoaly-is of gro'- the health oi > jn-t .ike the .-- j . , who might boast of a 99kj per cent ' ^seovery rate from a specific operation, the f vidual who happened to belong to that U per cent constitutes 100 per cent mortal ity for the individual. There is a very sharp ,,contrast there. Kow, when we talk about safe limits of toxic solvents, safe limits of toxic agents, afe limits of an industry, we must remem ber that the problem is not going to be solved by a blanket generalization oi a problem, but by a careful and meticulous analysis and study of the individuals ex posed to the industry. I know of no other , way that this can be done except that in dustry realize that the profession of medi- - cine forms the keystone to the solution of .' these problems. . j. , . .V; DR- BELK N A P: I simply wanted to am plify what has already been mentioned, and . that is when a welder or cutter works on '.'material that has been painted or coated 1vjwith lead, he, of course, probably will aclilquire lead absorption in a serious fashion about as quickly as, if not quicker than, in -lanyother way. .-1 It is very simple now, with the respira tors we have available, for a shop welder, whenever he is doing that type of work, to use such a respirator. In my own particular series of cases one of our cases of lead ab | sorption was a welder who had been re i pairing some ovens containing a large ' amount of lead. j Also, I had occasion recently to see half a dozen cases of cutters who were cutting j op tanks in a large chemical plant. These | steel tanks had been lined with lead. They oould not understand why the men were j getting lead. They went through the lead with a torch 3000 or -W00 degrees and they | absorbed lead exceedingly rapidly. It is not 1 difficult question to solve at all but it is a matter of having perfect confidence in what oo work is for and preparing for it. > "oMhRa.veCAhaRdR;insIntanccoensneocftioznincwicthhilwlseldfrionmg, "ork on galvanized iron. We have also had J.Uaa^itKntrT5bi soiling from the use c: ooated electrodes. j r ^ would also like to cail attention to r. 1 oative|y new development, that of the finn-.e oaning of metals before painting, by the `rrl special oxy-acetylcnc torch. T!:a: - r udes previously painted metals as w-i; as those which simply have mill scale on them. R. J. WOODHOUSE (Continental Cas ualty Company, New York City); I had a case a short time ago that I was called upon to investigate. The man worked in a small printing plant where he was assumed to have contracted lead poisoning. After mak ing impinger tests which proved negative, an award was given by the commission to the widow in the amount of $13,000. The lead was melted around 650 to 700 degrees and the experts proved that toxic fumes were not liberated. I wonder what yardstick the referees used to measure those cases, in the face of such expert testimony. MR. SKYRM : I would like to know the relation of hemlock poisoning and poison ivy to skin disease. DR. R EU TER ; Poison ivy, of course, is the most common plant that causes derma titis. Hemlock is occasionally the cause. Poison ivy is an intense irritant to most people's skin. It is a question of whether in itself it is not an irritant to ail people' skin. We used to think we knew the cause of poison ivy dermatitis, but more recent work has tended rather to disprove that we do know the actual cause of what it is in the plant that produces dermatitis. Appartilily it is a watcr-soiublc fraction rather than an oil. Its relation to occupational disease de pends on what the individual is doing, if lit is exposed to it in his occupation, for ex ample, as a farmer, W PA worker, lumber man or any occupation that keeps an indi vidual out-of-doors, and he contacts poison ivy, it certainly would be an occupaiinnui disease. Poison ivy dermatitis is apt io lie a mudi more violent dermatitis than that from hemlock. CHAIRMAN P A IN E : Mr. C,iimner, will you repeal your question? P. \V. GUMAER: The question was, what is ihc basis oi the comparatively low maxi mum concentration of toluol in the nlxcnce of any reported occupational di.-ca-e cn>e-. and arc there ar.y experimental data to war rant *uch a low concentration where -nei: -..sperimenta) data deals with chrome |*w.n- " and not wit:: acute poi<onittu: iiii? 1 W ili1 Mir:-;: TT-1'- 7'', 1 ;.vi .'9 /// Xuii i uhi, .Vn/V/v t'imi/ri'SJ this ventilating current be interrupted tor a period ut 24 hours and with the same amount oi methane being liberated, there would be 5,760.000 cu. it. of explosive mix ture. Should this be contained in an entry !0 ft. square, the length of the entry would lie approximately II miles. Methane detectors are now available which will automatically indicate and record percentages of methane. One type may be located in working sections on cutting and loading machines, in the last breakthrough and along haulage roads. This can be ad justed to give a warning by a signal light or other means at any predetermined meth ane concentration. For example, at 1 per cent or any specified percentage between .5 tier cent and 3 per cent, it will operate -pecial electrical circuits through suitable relays to cut olt the power in a section or give warnings in other parts of the mint to the outside. Methane recorders tor ^ linuotisly indicating and recording methyl in main returns particularly have been pj, fectcd recently and are designed to be ^ rated in fan houses or other con"v'rniect places. There is no relation between the vplUot of methane given off in a coal mine the chemical composition of the coal, as boti hltuminotis and anthracite mines prodoa methane, and methane has been found b metal and other mines when tunneliar through carbonaceous shales. The comma occurrence and cxplosibillty of methane ate responsible for numerous mine disasters ixti every precaution should be taken to keep it within safe limits. This can best be doce Iiy the use and guidance of methane detec tors. v Pulmonary Diseases in the Mining Industry By DR. R. R. SAYERS Director, United States Bureau of Mines, Washington, D. C. Although the attention of those interested in diseases peculiar to mining has been focused recently on one dust disease--sili cosis--other respiratory diseases may cause more suffering and economic loss. The in creased incidence of these diseases usually Is attributed to exposure to abnormal air conditions underground, such as sudden changes from high to low temperatures, ex cessive dust, and noxious gases. The prin cipal respiratory diseases to wltich the miner is subject are bronchitis, influenza and pneu monia, pulmonary tuberculosis, anthracosilicosis, and silicosis. Although the mor tality statistics in some of the tables in cluded in this paper are old they have been corroborated by later, less complete data. Bronchitis Bronchitis is an inflammation of the bronchial tubes due, among other causes, to the inhalation of irritants such as dusts (organic and inorganic). Occupations that entail exposure to atmospheres polluted by irritating gases carry with them the risk of bronchitis. According to Coliis,1 it cannot lie distinguished clinically from bronchitis occurring among the general population and its association with the inhalation of dust or gases usually is unrecognized. During middle life bronchitis causes mod' recurrent invalidity and incapacity. Mortal ity records compiled by Coliis' indicate- that it is of a chronic traumatic origin asso ciated with irritating atmospheric condi tions, rather than of an infectious origin.. Statistics for bronchitis for the gencr2 population and for workers exposed to doss in Great Britain1 for 1921-23 show the nde played by dusts in the increased incidence of tlte disease in certain industries. Tor comparative mortality per thousand (is 26 to 65) for those in occupations expose to siliceous dust was 214, for those expos to nonsiliceous dust 59.5, and for the Vs " eral population 49.6. {See Table 1.) In this connection it is interesting to tlte mortality statistics per thousand 26 to 65) for coal miners of countie ^ Wales (in which most of the coal nun ^ anthracite) compared with those f(r ^ other groups in England and figures for coal miners are-412 ^ derground workers and 139 for getters compared with 46 for mae*. same social class and 50 for all occtip retired males. (See Table 2.) Put** In a study by the United State* Health Service1 35 cases of chron Table 1.- pupations Siliceous d Nonsiliceoi Onerai pool iilis were f to anthracii in the stud Ifines and t fidier, Okla. ass or tube aong men v tis, pleurisy Title 2.--C ces for Bro Groups *eaj miners1. All undergo Hewers and hies in same "occupied a ht of rate hrsto rate I ' h three coui !*w 3.-- Inf among E Octobe nod !f k-45 rXh 523 .1/ iiiuitj Section 531 ;l,c ""et, ;s 'or 5 mthjr, P. I to b t ooi'oa, 1._M ortality per 1.000 from Bronchitis in D usty Occupations and in the Tbte General Population, by Age Groups Ages at Death Comparative Mortality Figure u'c voluo, i mint jaj al, is b, cs Prod\*j :t found a tuniKlinj !>o commas methane irt 'Sisters ir.d i to ketpit -st be d<e brute dure. causes much :iry. Morul as' It trig > eric coni:.us origin, the genenl -ted to dti ow the role ;d inridatcr stries. Tie tsand (a its exposeJ osc expstef or the { e 1.) ting to rote sand (-Sf; counties s' ial mired < -e for r*' .Vales.' for all hewer > calcs io ccup'.ed Xeupatioits cxPsetJ t0 Siliceous dust . ........... ' Koasiliceous <Just*'"' Ctoeral population. . .. 20-- 25-- 55-- 45-- 55-- 20--65 1.1 1.0 13.7 44.6 153.7 214.0 4.9 12.8 41.8 59.5 .5 1.7 5.4 13.3 28.8 49.6 tis were found among 344 employees of fdc anthracite mining companies examined. v]n the study conducted by the Bureau of nes and the Public Health Service at fidier, Okla.,' the highest incidence of siliosis or tuberculosis, or both, was found pong men who reported having had bronjfctis, pleurisy, and asthma. Table 2.--Comparative M ortality Figts.for B ronchitis per 1,000 of Certain 'Groups in England and W ales -SjMj- . JoaJ miners1................................. -vAJI underground workers......... ^Hewers and getters.................. lilies in same social class........... Alloccupied and retired males.. . litio of rate for hewers and get tersto rate for same social class. Bronchitis 112 139 4(> 50 302 ' In three counties in Wales. Title 3.--Influenza-Pneumonia Mortal*7 among Bituminous Coal Miners-- October to December 1918 Influenza and Pneumonia Figures of mortality available for 4,700 miners insured in the group department of the Metropolitan Life Insurance Company1 show that in the last quarter of 1918 during the influenza epidemic 64 of these miners died of influenza or pneumonia. This is equivalent to an annual death rate of 50 per 1,000. Among all occupied males aged IS years and over, the rate from influenzapneumonia in the same 3 months was 22 per 1,000 or less than half as high. In the age period 45 to 63 years the rate among bitu minous coal miners was about four times as high as among all occupied males in the same age group. (See Table 3.) Influenza and pneumonia, as reported, were responsible, in the years under study, tor 31 per cent of the mortality in the group of bituminous coal miners at ages 16 to 70 in Indiana, Missouri, and Wyoming com pared with 19 per cent among both farmers and "all other males" at these ages in the same counties. (See Table 4.) In 1918, the year of the great epidemic, influenza and pneumonia deaths constituted 55 per cent of total mortality exclusive of accidents among the bituminous miners in contrast with 27 per cent among the farmers and 34 per cent among all other males. These percentages were not as high as the figures for Wilkes-Barre. The fact that the soft-coal counties tinder consideration are largely rural areas may have made some difference. In the epidemic year 1920, the proportion of deaths from influenza and pneuiponia was smaller than in 1918, but, as was'found ior the anthracite miners, the bituminous croup showed a wider difference in the pro- ! i 1-: # 1 M:- :! ' ' i h r:F'`lfO- ' t.-vV , is/V-'-vtV ; ,vV- .... tv - v'-'.-' w v. fl i: M *A< ' 4 i 'i' ' jt.. iJ I lS|Hj r -1 'V r 4:; u' if Htifl : : mw M mm H h ) lS SiPulh ` f?:& S H itinU ' il?r;!;:V i-fpi i *.*-*i-.. Ut'U- ?'WKfJ| *. Pr-*:* - sjw'J ; i ; s?!r 532 29th X a i intuii Suf r y Cunqrcs.i Tablee 4.--Percentage of Deaths from Influenza and Pneumonia (A fter Deduct' l-jble Acci dents) Among Bituminous Coal Miners Compared with Farm ers, and y/f I Other Males in the Same A reas of Several Soft-Coal Producing S tates1 lUl j ^ = Male Groups Under Comparison 1 16-70 liituminous coal miners............ . J 31.1 Farmers....................................... 18.7 All other males............................ ..i 18.6 Ages 16-30 1 31-40 41-50 51-60 61-70 49.4 ! 44.7 25.1 ! 19.7 38.4 ! 32.4 19.7 ! 12.4 16 g 30.U ! 29.0 16.U 1 11.J 10.8 .'0. inclusive, S cnnl counties nf M issouri. 1917-21. inclusive, and tin* 6 principal cual-producing countiM ,,f Wyoming, 1919-22. inclusive. The record for farm ers and fur "all oilier males" was obtained from the ahove-m entionrd coal-mininc counties, and'aiao from 4 acricuitural counties of W yoming. 1919-ZJ * I ccupations Siliceous c Sonsilicec [.lenenti pop portion oi deaths from this cause compared with "all other males" than in 1918. The percentages in 1920 were 29 for the softcoal miners and 10 for "all other males." In this epidemic the bituminous miners at ages 40 to 60 suiTcred heavy excess mor tality from biflticnza-pncttmottin, bat the differential mortality was not quite so great as at ages 16 to 30. Among hewers and getters of soft coal in England and Wales, the death rate from in fluenza and pneumonia, 1921-23, was about 12 per cent greater than among males of comparable social status (social class 3). The difference was found to be 5.8 times the probable error of the difference which is certainly a significant variation..' Thus, an abnormal mortality from influenza and pneumonia is consistently indicated among miners rt coal--both anthracite and bitu minous--in England as well as in America. The pneumonia mortality figures in 192123 for occupations in Great Britain exposed to siliceous and nonsiliceous dust compared with those for the general population were given by Collis' as I34.J, 76.0, and 85.3, re spectively; similar figures for Influenza were 47,1, 49.6. and 36.5, respectively. (See Table 5.) According to Brtmdage,* an outstanding feature of the statistics of death for hardcoal miners in the United States is their extraordinary mortality from influenza and pneumonia not only during influenza epi demics hut at other times as well. In a" study hv the Public Health Service at Wilkes-Barre. Pa., in 1915-23 and 1906-25' it wa> found that influenza and pneumonia were responsible tor 40 per cent of the total deaths compared with 25. per cent among males at ages 15 to 65 who had heen en gaged in pursuits other than coal mining ,, Wilkes-Barre and vicinity. The percentage of deaths from influenza and pneumonia for these two groups by ages for the yean mentioned was 19.3 for anthracite miners compared with 13.3 or males in other o- dustrics. (See Table 6.) Tuberculosis out twice, X od for ages In 1925 Collis* said that tor coal miners lie rate fo; .generally the tuberculosis rate apparently a Tiehighest low although miners at the coal face suffer'' taberculosis from the disease more than other coal mk" ss (men w ers underground and workers above ground. Wing or r Results of more recent investigations seen'; , 3 years) to contradict the assumption that tubertu-"' ^tiich more losis tloes not occur among coal miners. Aa" wtk, 37 p investigation by the Welsh School of Med clmonary t icine, reported in 19.v.` indicates that this tompletcly c supposed exemption of coni miners frota trs, which r tuberculosis may he due Co a mis- or paruil d tubercule diagnosis. This invest cation revealed a high hr pulmou: incidence of tuberculosis (35 per cent if the vould appe: "probable" cases are included) among the Welsh Xatit imcumoconiotics of the South Wales coal fate that fields and supports the theory that coal dug tuberculosis modifies the tuberculosis, leading to failure 111 incorrect to recognize the disease or to the mistake's *t the ah- diagnosis of "bronchitis." Studies hy the United States PuW"j Health Service" revealed that 6 per cent o hard-coal miners examined had clu'1' _ pulmonary tuberculosis. The average P ^ alcnce in the adult male population ot Uffited States is about 2 per cent. The P^alcnce of pulmonary tuberculosis ff" bard-coal mining employees at ages j 35 was slightly less than that found th studies among male adults in^ the Se . population, fn the age group 35 to 4 . ever, the prevalence of tuberculosis Table 6._ ] Miners i',bnl,,l,a1rmaciottcl ms wmmmm Mining Section 33 A fte r D educi rm ers, and V/iT ing States' u bie 5.--Mortality per 1,000 from Pneumonia and Influenza in D usty Occupations ' and in the General Population Pneumonia 51-60 61-70 19.7 iT~ i 20- 1121..43 1100..88 OcSciluipceaotiuosnsduexstpo.s.e..d....t.o............... 3.3 oi i naiana, ifi^, Xonsiiiccous d u s t................... producinff couiui^s is obtained from it General population.................... 4.3 iminc. 1919-23, han coal mining a Occupations exposed to The percent^ ,rSNiloincesoiluicsedouuss td..u..s..t....................................... 5U.4 and pneumonia fa General population.................... 2.0 4cs for the yean anthracite minen mates in other b- Ages a t Death *5- 35- 45- j S3- 14.4 30.6 j 47.2 I 38.7 9.6 13.7 2S.7 I 23.9 11.5 19.6 I 24.2 ! 25.7 Influenza 7.7 11.3 1 8.7 1 18.3 4.8 13.7 I 10.6 : 14.9 5.2 7.7 j 0.7 ! 12.0 : 1 C om parative M ortality Figure 20-65 134.5 76.0 85.5 47.1 40. 0 56.5 :at fo r coal raiaen 's rate apparently it th e coal face suffer th a n other coal mis* irk ' bove ground in gations seen u io n that tubercu.in;z coal miners. Afi '-h School of Med- indicates that thu coal miners fro? to a mis- or partial t ion revealed a k:?1, C35 per cent if tee :lu d cd ) among ih S o u th Wales cal icory that coal d -' .. leading to ftuien nr to the mistal" jbout twice, at ages 45 to 54 about 5 times, and for ages aliove 55 it was about 10 times the rate found in the general population. Thehighest prevalence of clinical pulmonary tiberculosis occurred among the rock workin (men who had been employed in rock loading or rock extraction for more titan 2 * 3 years). After 20 years' service, of y.vhich more than 2 or 3 years were in rock trork, 37 per cent presented evidence of pulmonary tuberculosis. In a group of 135 completely disabled former anthracite work ers, which did not include any known cases of tuberculosis, 10 per cent proved positive for pulmonary tuberculosis. These findings ould appear to corroborate those of the Welsh National School ot Medicine that in dicate that the supposed exemption from tuberculosis of coal miners Is erroneous due 10 incorrect diagnosis. There is evidence fat the aliove increased incidence of tu berculosis is associated with exposure to silica dust. The incidence of tubcrcuiosis is much higher in metal mines than in coal mines, due no doubt to exposure to dust containing a higher concentration of silica. An investi gation in 1914 by the Bureau of Mines in cooperation with the Public Health Service of pulmonary disease among the zinc miners of the Joplin. Mo., district, revealed a high death rale from pulmonary tuberculosis. The mortality rate for tubcrcuiosis for Jas per Comity was 200.8 per 100.000 for 911 and 1912 ami 229.7 for 1913, according to statistics of the State Board of Health." Oil the other hand, according to the Jasper County Anti'.ubcrculosis Society, during the calendar year 1912 there were 720 deaths among miner- who had worked 2 years or more tmderer: und in Jasper County. Xot ail ted States Publfr ! that 6 per cert c; lined had chn.ra The average o population ot per cent. The f ri^ aiberculosis vees at ages tha: found ik-*': :ults in 'he . r o u p j a 10 ^ : tnbereuiosif * ' Table 6.--Percentage of Deaths from Influenza and Pneumonia among A nthracite Miners and among Males in Occupations Other Thar. Mining in W ilkes-B arre and Vicinity 1iroups l nder Comparison ^baracite miners........... *s *n other industries. 15-64 39.8 25.5 15-24 45.2 28.7 A-es 25-24 35-44 67.9 42.9 46.2 31.0 45-54 51.8 16.8 55-04 ](>..r 15.5 v t Mi mi* diilil te i! Ftpit-sJ V P i :a j j i ' -. VA. y \54 29th Aaliona! Safety Congress Table 7.-- M ortality per 1,000 from Pulmonary T uberculosis in Dusty Occupations Tibie 8,-- P and in the General Population Ages at Death 20- Occupations exposed to Siliceous d ust.............. .25,6 Nonsiceous dust....... 13.1) Ocncral population........ 211.6 ni tlu.se 720 deaths occurred in that county hut they had contracted the disease there and some of them had moved away. Of 93 miners in the Joplin District examined hv Lanza in 1914," 64 showed definite symp toms of pulmonary disease and 39 of the 64 had the classical symptoms of pulmonary tuberculosis. In a study by the Bureau of Mines and the Public Health Service" in Butte, Mont., during 1916 to 1920 the death records of the State Board of Health were examined. These showed that during 1915, 122, during 1916, 126, and during 1917, 169 Butte miners died of tuberculosis. The significance of the death from tuberculosis of 169 miners in 1917 is indicated by comparison with the rec ords of other regions. In 1917 approxi mately 14,000 men were employed under ground in Butte mines; with 169 deaths iront nitierculosis for the year, the rate per 160,600 was 1,207. The tuberculosis death rate of Michigan for the 10-ycar period 1910 to 1920 was 97.4 per 100,000; hence the tuberculosis death rate of Butte miners was nearly 13 times as great as that of Mich igan. The part played by dust, especially dust containing silica, in the production of pul monary tuberculosis is shown dearly by figures for Great Britain for 1921-23.' The death rate per 1,000 ior ages 20 to 65 was 592.2 for those exposed to siliceous dust, 172.4 for those exposed to nonsiliccous dust, and 63.5 for the general population; for ages 35 to 44 the figures were 141.0, 46.1, and 43.6, respectively; for ages 45-54 the figures were 211.6, 56.4, and 39.0, respec tively: and for ages 55 and over llic figures were 150.6, 29.9, and 22.7, respectively. (Sec Table 7.) According to Collin' the prevalence of bronchitis, pneumonia, and tnhcrcnlo-is is 2.4- : 3.5- 1 45' J 55- 20-64 putcoo r nnri ir jnrioor mduatr 63.4 14t.(l ; 211.6 26.3 j 46.1 j 56.4 37.6 j 43.6 j 39.0 150.6 29.9 22.7 592.2 172.4 163.5 (oil tr a d e ... . Alcohol trade . Feat ni fumepu<f or 1. Animal or l Vegetable high among those exposed to silica dust but materials j. >ilcn . . . Ihc incidence of these diseases is not always the same under other conditions such as exposure to other dusts, heat and fumes, or working indoors. (See Table 8.) iundrr of inst. wn probably A n thracosilicosis pby?:cai conditu rock `workers, a: Prom 1931 to 1937, 87 per cent of the able exposure total deaths in Great Britain due to silicosis adannes also occurred among the coal miners of Souti_ ra te r physical Wales; two-thirds of the deaths and dis-., a the control gre case occurred in the Swansea Division; and; ' Moderate o r n 89 per cent of the medical certifites--, from any cause . granted in the Swansea Division related W, ie control grot anthracite collieries." IS miners, i In the United States the chronic disease ; ^ rock workers. among miners due to breathing air contain TWe was a n ing dust generated in the various process :n the pro; involved in the mining and preparation o> Sirmetts with i anthracite is called anthracosilicosis. This i< JKrs of employ a descriptive title for the form of pneumo is man coniosis commonly called miners' asthma- *^rs disability 4 The disease was found in about 23 per cen pulmonary of 2,711 employees of three anthracite min * disability due ing companies studied by the United -tat Public Health Service in 1933. About per cent of those hav'ng nmhracosihco;, showed evidence of disability, compared less titan 10 per cent in the control TM." ^ the occ selves accord as fol. ? rtVu!ar miner * more than 100 Moderate and marked degrees of ",sa handicapped aproximatciy 21 per c' n those with anthracosilicosis compare ' ^ J ,c of a ir; tx.itpt rock a (` thology c less than 2 per cent of Ihc men `cr' in control-. a these cas c of coal dust 1 Wide differences were bound in tent of physical impairment in the ^ oi occupational groups. The highest - ( v /,n extensive ft ^Uj6 -th asso- .Usability from all causes found, in the group of men that Ha ^ `-xccss mo more than 5 years before the amination from very dusty to r e la ti' , lusty occupations the industry- whole t^,. ard<oal rnii * ** made by the Minili!/ Sedim i Dusty O ini. . * ^.prevalence o{ Bronchitis. Pneum onia and T uberculosis Under Certain UMU* Tbi.t Conditions of Exposure "'4 Z Exposure door and indoor life ijfoof industries.......... MSItlohto"l dtrcadJ e................................. Ijjat and fumes............ Bronchitis low low high moderate high Pneumonia low low high high high Tuberculosis low high low hi^h low >scd to silica dust but diseases is not alwjp conditions such u s, heat and fumes, Table 8.1 . - r S ilico s is - . 87 per cent oi tk j J r tain due to silicaiis^ coal miners of-Soctic the '~aths and dis-y iw i Division; tad metrical certifiato ` ,i Division related to s (lie chronic disea breathing air containthe various procs z and preparation o* iracosilico-'is. This ;Jie form c: pneurw lied miners' asthma in about 13 per cm three anthracite n*' hv the United Stair* in ion. About v . ne nmi:rnco?ilic^` ibilitv. compared if ;n the cr.r.rrol decrees or disabi1*^ telv 21 ;cr cent ' oosis cr.uv.'jred the mw serving 2 Inumi - the ty . -Hunt ::: :'::c n,c hVtr-t ratr- .uses c.r.:'H's'd "* .ivu that had chfs'" ore the -:.v.e 01 ^ -.v ,o rr-sv-vclj-.P 28? Animal origin.. . . low Vegetable husks and debris, certain inorganic ^materials high ; Silica high lOW low medium Jon high high ber of instances the change in occupaprobablv was made on account of [sital condition. Miners at the coal face, workers, and men who had had appre- ile exposure to harmful dusts in other 5dustries also showed evidence of much Ijreiter physical impairment than was found " ie control group. derate or marked physical impairment n any cause was found in 1.7 per cent of `J S 'control group, in 9.9 per cent of the miners, and among 12.6 per cent of die rock workers. There was a marked tendency toward in crease in the proportion having physical imfainnents with increase in the number of rears of employment in anthracite. This 'tendency is manifested whether one con ifers disability of any kind, disability in which pulmonary infection was contributory, ,r disability due largely to tuberculosis. In *jrh case the occupational groups arrayed tnemselves according to extent of physical wpainr.ent as follows: (1) Rock workers: p) reSular miners: (3) all others exposed " ore than 100 million dust particles per " oic ioot of air; and (4) men in haulage*ays except rock workers. Pathology of anthracosilicosis as obthese cases is essentially a deposi- , > coal dust in the lungs, accompanied ,*j* Extensive fibrosis, both diffuse and I/"u lr - with associated functional and de- ,tI?t''ve changes, (silicosis modified bv waidusii. T ^ t execs mortality from ;'.-tptratory ;d<,4Unsci s-; a '.hole is experience*5 by Ameri.j*^ard<rj,*; miners is clear irom the "`-adv r.y the Public Hot;:-. : Service.4 The anthracite miners' proportionate mortal ity from all respiratory diseases was about \'A times that of the other adult males in the same region. When proportionate mor tality was computed for ages 16 to 65 in Wales,4 it was found that respiratory dis eases accounted for 53 per cent of the deaths of anthracite miners compared with 38.2 per cent among males in the same social class. The proportion among hewers and getters of anthracite therefore was 1.4 times that of men of the same social status. Silicosis There arc various definitions of silicosis hut all agree that the cause of the disease is the inhalation of silica or quartz dust.14 Silicosis is a wcll-rccognizcd clinical and pathological entity at least as characteristic as that of am- cause of death known to epidemiologists." The definition oi silicosis, adopted at the International Silicosis Con ference in 1930 and reaffirmed at the 1939 Conference and generally accepted is: "Silicosis is a pathological condition of the lungs due to inhalation of silicon diox ide. It can he produced experimentally in animals." The first investigation of silicosis in the mining industry in the United States was made in 1914-15 by..the Federal.Eareau of Mines in cooperation with the United States Public Health Service in the Joplin (Mo.) mining district." As only a few men were examined at that time, it was decided to examine a larger number to gain a more accurate, idea oi the prevalence oi tt-.nsumptiott among the miners oi this distrl". From -i) 'X K i - y S t S i i ; 29ti: Xalional Safety Congress May 15 to December 31, 1915, "20 mintn were examined; 45.7 per cent had silico'Sl! and tuberculosis and 5.3 per cent had tu. berculosis." A later report (1917) of ih;s same investigation by Lanza and Childs included the results of the first detailed X-ray studies of silicosis made in the United States. Investigations of mining conditions by Harrington and Lanza" in Butte. Mont u 1921, revealed that 42.4 per cent of 1,01J miners examined showed definite signs of lung damage due to dust. From July 1, 1927, to June 30, 1932, the Metropolitan Life Insurance Co., the Tri- State Zinc & Lead Ore Producers Associa tion, and tire Federal Bureau of Mines op- ' crated a cooperative clinic at Piclier, Okla," to demonstrate to industry a workable method for diagnosis of silicosis, to educate workers in preventive measures, and to serve as a model to industries presenting a dust hazard. Of 27,553 individuals exam-! ined during this period 5,366 had silicosis,'! 742 silicosis plus tuberculosis, and 320 un-T complicated tuberculosis. .-Jag The chief cause of disability in silicosis is tubercle infection. The silicotic lung appears to be a more favorable medium for the growth of the tubercle bacillus than the,, normal lung, not because it is fibrotic, nor because its lymphatic drainage is interfered with, but because it contains silica." Ap- ; parcntly silica dust possesses this character istic of increasing the liability to pulmonary tuberculosis. That this is true is indicated by the statistics quoted in this paper which indicate also that silica dust increases the liability to other respiratory diseases. (See Table 9.) ;'! The results of virtually all studies are agreement regarding the high mortality ra from tuberculosis for industries " 11 4 large numbers of men are exposed to silica hazard. These rates arc so lug > they leave no room for doubt of the ca and-cffcct relationship between tiie 19 and the high mortality* Joint studies made by the Actuarial cicty of America and the Associa1 Life Insurance Medical Directors re ^ that there were 63 deaths where 6 " ^ura. pccted (about 11 times the experte ^ ber) from tuberculosis in 1925-193 ^ 0( a group of underground miners, ilio bercu t-'P ibe e-' and < imonco'-er rimes , id a An Saran of 5.C haiatii dust 5 lu b e r e of rea of mi in a p i fini s seconc third s Prev The is the m o rtal arced dust a silicosi prtven fir is centrai Ihe w o Proper: parity compo: itm osp Particle Althc breath Qted b 1 higher nsitlc 11 p0 'bit, n Proporr W irtz, 'be fin Enough U1 dc Jcont Mining Section 537 jer 31, 1915, 720 mintri v7 per cent had silicosi, nd 5.3 per cent had to. _-r report (1917) of this by Lanza and Childs" '.ts o the first detailtd licosis made in the United ,,liom were employed in metal mines. Tu. f(.ulo;is deaths were fourteen times the ^pected among copper miners, nine times ^expected among gold and silver miners, pi eight and a half times the expected 20101VC' icon miners. In an earlier study" (overing the years 1915-1926, there were 18 limes as many deaths as expected among d and zinc miners. -t mining conditions anza" in Butte, Monh, i t 42.4 per cent of UOiS showed definite signs o( 0 dust. An analysis by the field division of the Saranac Laboratory1' of the roentgenograms of 5,000 white miners exposed to the ini halation of harmful concentration of silica dust shows that the incidence of pulmonary J27, to June 30, 1932, the tuberculosis lesions increases as the degree Insurance Co., the Tri- i of reaction to dust progresses. In this group 1 Ore Producers Associi- of miners tuberculous lesions were found :ral Bureau of Mines op- m approximately one-fourth of those with .c clinic at Picltcr, Okla.,* first stage silicosis, one-half of those in the to industry a workable jtcond stage, and 65 per cent of those in the asis of silicosis, to educate iJhird stage." entive measures, and to to industries presenting t ,"Prevention o f D u st D ise a ses in M ining : 27,553 individuals exam- period 5,366 had silicosis,' vsThe data given in this paper point to dust s tuberculosis, and 320 im- is the greatest contributor to the excessive reul- -Mortality from pulmonary diseases experi- facti is the mining industry and to silica of usability in silicosis is , .dust as the immediate cause of the disease .. The silicotic lung appears I silicosis. Therefore, the principal method of `avorable medium for the ' preventing these diseases is to eliminate as tubercle bacillus than the h fir a? possible or reduce to harmless con- because it is fibrotic, nor ttatra-.icr. the dust in the breathing zone of antic drainage is interfered the workers. Experience has shown that the e it contains silica." Ap- propenies of a dust that determine its cait possesses this character- Wcity :o produce injurious effects arc its : the liability to pulmonary | tampo-ition. the quantity suspended in the it this is true is indicated - ^osf.-.ere breathed by the worker, and its looted in this paper which Particle size. t silica dust increases the respiratory diseases. (5 Although any dust may be harmful to "fcath under certain conditions, as indi- a jed by tiie data presented here that show virtually all studies are i" 1 nigher incidence of pulmonary diseases in ting the high mortality ra'r* Bnsil.cous dusty industries than in the gen- is for industries in A P-Ptalation, physiological studies reveal at men are exposed to T**if- raining the harmfulr.ess of a dust is iiese rates are so high lr-^ "Portxnal to its content of free silica or am for doubt of the J1!1- n particles small enough to enter mship between the hat* P spaces 0 j tp,e lungs, and in high tality." jq! conccntra:!on to overcome the. nor- 'I **0" uadc by the Actuarw* - 4-emes ot" the respiratory system. a and the Associatio" itiacti. ;reycmior- 0I" diseases is the 'fiCcdUilcCaall DU iiirewciitvo-"rs-" r5U-3t'N' i '- ot th^e iphysi`'cilualnl aa.n.VdI Hthite. iennsguinleienr.. >-o5 dtlecaiithhss where 6 "efeUI_B- \ ^0iicii:cr to determine the extent oif 1 times the expected v eulosis in 1925,1930 a p ; ergroundi mo-1 ^zani in industry nr.l method for The first step is to determine witat dusts arc harmful and in what concentrations. The procedure is somewhat as follows: It is ob served that respiratory diseases appear more frequently or with greater severity among workers in certain industries or in connec tion with certain operations within an in dustry. The physician attempts to determine the extent of the injury to the health of those exposed and the cause. If the cause appears to be exposure to excessive dust, the engineer samples the air to determine the kind, amount, and size of the dust pres ent. The physician and the engineer can correlate the results of their investigations to determine allowable concentrations of dust, exposure to which is not likely to cause harmful physiological reactions. The en gineer is then in a position to devise meas ures tor the reduction of the dust to a harmless concentration. The aim, of course, should be to eliminate the dust entirely or to reduce the dust to a concentration that will not cause disability during the working lifetime. Allowable Concentrations of Dust in Mining Investigations conducted over a period of years show that exposure to certain concen trations of harmful dusts for a certain time causes varying degrees of respiratory dis ability hut that below these concentrations disabling pulmonary diseases do not occur within a working lifetime. The classical ex ample of this is the experience in South Africa with the reduction in mortality from silicosis that has followed the reduction in air dustiness in the mines of that country. The reduction in the incidence of silicosis in the South African mines attests the ef fectiveness of the control measures em ployed and the practicability of using a defi nite dun concentration as a guide in setting allowable limits of air dustiness in the pre vention ot pneumoconiosis in dusty indus tries. The production rate of silicosis in the scheduled mines of South Africa" in 193235 was 9.59 per 1.000 compared with 21.95 in 1917^,5. fSee Table-10.) Tl:e incidence rates for silicosis uncom plicated hv active tuberculosis among South A frican m iners in 1936-1937 was between 8 and 9 -cr 1.000 per annum ." T he liability am one tile whole body of m iner- to con trae: Me disease in 1936-37 was less by 6a ' 1.! ink m T<;*Ji Table 10.-- Average N um ber of Miners Examined A nnually and Production Rs. for Silicosis in Each Triennial Period Since 1917-1S t! i 'cnexi t'l 17-20 1P2U-2S r>2.*.2o Average Number of Miners Examined Annually 14,070 13,260 12.523 Production Rate of Silicosis per .CKKI 21.95 t9.I(i .U.2S per cent than it was in 1920-23. Among the "new Rand miners" who entered the indus try by way of initial examination since 1916 and who have been exposed solely to the progressively improving occupation condi tions that have obtained since that date, the liability to contract silicosis was less by 87 per cent than the similar liability among all miners working for an equal period in 192023. These "new Rand miners" constituted 77 per cent of all working miners examined. The group of pre-1916 miners, who in 193536 constituted less than 17 per cent of the total number of working miners contributed nearly 78 per cent of the new cases of sili cosis. In the study by the Public Health Serv ice" of anthracosilicosis among bard coal miners silicosis was not found in a control group of mining employees whose dust ex posure averaged less than 5 million particles tier cubic foot of air. The prevalence of anthracosilicosis among the entire group of employees was found to be about 23 per cent. Among all except rock workers, less than 2 per cent of the men developed anthraco silicosis when the duration of employment was less than 15 years, regardless of the amount of dust in the air. Among men exposed 15 to 24 years to dust containing less than 5 per cent free silica, 14 per cent of those who had worked where the average dust count was 100 to 199 million particles per cubic foot, 29 per cent of thois_exposed, to 200 to 299 million, particles, and 58 per cent of the men who had worked for this period in more than 300 million particles per cubic foot, devel oped anthracosilicosis. Period Average Number of .Miners Examined Annually Product in Rate of Silicosis Per 1,000 IP2-29 14.624 21.11 1929-32 16.774 13.87 1932-15 20,139 9.59 Among men employed for more than 25 years in dust containing less than 5 per cot tree silica, the proportion of persons found with anthracosilicosis under different con centrations of dust was as follows: 5 to W million particles, 7 per cent; 100 to 199 mil lion particles, 54 per cent: 200 to 299 mtUtoa particles, 71 per cent; 300 or more million particles per cubic foot, 89 per cent. With the exception of miners, their help ers, and rock workers, about 25 per cent of all the men employed underground devd- oped anthracosilicosis after a working period of more than 25 years. This group was ex posed to dust having a quartz content of. about 13 per cent. ^ The prevalence of anthracosilicosis amongy persons who had been exposed for more than.' 2 or 3 years to dust of which about 35 per cent was free silica, varied from 10 per cent among those who had worked in concentra tions of less than 200 million particles per cubic foot for less than 15 years, to 92 per cent among those who had been employed for more than 25 years in dust concentra tions exceeding 300 million particles per cubic foot, more than 2 or 3 years of which time was spent in rock work. Age per se appeared to play a minor role in the development of anthracosilicosis. Analysis of the data for the purpose ctermining safe limits of dust exposure i icatcd that employment in an atmosp sntaining less than 50 million dust fW ` ^ er cubic foot would produce a neg 'S' utnbcr of cases of anthracosilicosis " ic quartz content of the dust was ies per cent. In the gangways where t intent I.o--f..th_e__d_uh,s-t was 10 to about 13 b null"" I* 09: Numoer Xumber Percent lb-24: Number - Number Percent 25-49: Number Number Percen t 50 and ove Number Number Percent particles p {ration for it 5 to 10 air. Sirail Public He: poeomocon vorkers. ( The rela (ration and Mage of coniosis \v: vorked in million pa: hr, 9 per years, 20 p 15 years, ; those who lion of 25 Pneumocon '5 pears, a those who " f t ration Kr cent ha 17 Per cent The data IrJ^es, an; ^ui'actu: f t" treate yhded sirr *p. Mining Section 559 Auction Rltt| , | e u . -- Pneumoconiosis Cases Occurring Among 798 W orkers Exposed to Mixed D u st, Classified by Average Dust C oncentration, Length of Employment, and Number of W orkers Exposed Production Rate o Silicosis Pr 1,000 Average Dust Concentration (Million Particles per Cubic Foot) Years in Industry 0-4.9 5-9.9 10-14.9 15-19.9 20 and Over 21.11 13.8; 9.59 more than 2 than 5 per eta persons tound different conollows: 5 to 99 100 to 199 mH0 to 299 million >r more million er cent .'.i. mers, their helpit 25 ner cent oi erg- ' dew!> wo. i period group was x* .tartz content of osilicosis amonj d for more this ch about 35 pn rom 10 per eta ,-d in concentnm particles P<s years, to 92 per been employedust concentnn particles F"1 years ot |u '0-9N: umber of pneumoconiosis cases............... Number of workers exposed........................ Percent with pneumoconiosis...................... . 10-24: . . * Number of pneumoconiosis cases............... Number of workers exposed........................ Percent with pneumoconiosis...................... 2>49: . . Number of pneumoconiosis cases............... Number of workers exposed....................... 5 Percent with pneumoconiosis...................... $0 and over: *. Number of pneumoconiosis cases............... T Number of workers exposed....................... -"'Percent with pneumoconiosis...................... 5 k _ ------------------------------------------------- W ' w * (particles per cubic foot. The limit of tol,,gefation for rock workers was set tentatively 5 to 10 million particles per cubic foot of air. Similar results were obtained by the Public Health Service in an investigation of pneomoconiosis among mica and permntite workers. (See Table 11.) The relation of the average dust concen tration and duration of exposure to the per centage of workers found to have pneumo coniosis was as follows: Of those who had worked in an average concentration o: 50 million particle? of dust per cubic foot of uri 9 per cent had pneumoconiosis in 5 years, 20 per cent in 10 years, 50 per cent in 15 years, and 66 per cent in 20 years. Of *jse who worked in an average concer.tra"n of 25 million particles 10 per cent had Pneumoconiosis in 10 years, 27 per cent In fears, and 33 per cent in 20 years. Of mose who had worked in an average ccmI ^"cation of 10 million particles of dust. 7 cent had pneumoconiosis in 15 year; and ! D tPec cent in 20 years. (See Fig. 1.) The data obtained in other studieS'oTSgsty ^Jjes, anthracite mining, asbestos textile y ulacttire. and the pottery industry have i -. Cceated in a similar fashion and have ,_e<le<i similar, although usually less regn- V'liltc The position of the ilircP- nM 0 81 0% 0 123 0% n 43 0% 0 45 0% 0 56 0% 0 94 0% 0 45 0% 4 44 9.1% 0 29 0% 0 66 0% 3 31 9.7 % 5 25 20.0^ 0 13 0 /c 2 29 6.9*;; 3 11 27.3;; 4 8 so.o'-; 0 8 o<; 4 23 17.4-; <\ IS 33.3'; 4 6 69.7 r,i. value below which no cases were found and the magnitude of the trends between per cent affected and both time and intensity of ex posure varies in different sets of data, de pending, to a large extent, on the chemical nature of the dust to which workers were exposed and possibly on the regularity of employment. It is tempting to seek to summarize the data of table 12 and figure 1 into a simple mathematical relation such as the follow ing: With each twofold increase in average dust concentration above 10 million particles per cubic foot, the probability of finding cases of silicosis (in men exposed for com parable lengths of time) is approximately doubled. Application of the standard meth ods of curve fitting would yield more re fined descriptions of these data. Neverthe less, it does not seem to he advisable to set up any mathematical treatment because, of all the men who entered the industry, only :hc survivors have been studied. There is no adequate wav of finding out whether or :fnt men who dropped out of the industry were in a better or worse state of health a- 'ar a< silicosis is concerned than men who .'.mained in tiic industry, and thn- there i- o way of introducing a correction for this -un-tit selection into a iua:i:emati'*al -r-V"-rit v2' :.; ~tv-yf^S h n ^K L 'tlIiXJ... ?!; & .J...vU-Ui*.~w. -.C i40 29(h Xuiiijiiai S'aiclv Cnnorcs.f ... ! ^ ,;y i S liili-J !-! f e : ! i"j ifivlvMi:' H iI mm ffe i1LMtl l i i j |i Ij-fe; iHS.<liVii3kit--4-l, ijfi mm ij f c m Shovcle men ) Sho^cie Drillers Trackm Roof tri Figure 1.--Relation of average dust concentration and duration of dust exposure to the percentage of workers found to have pneumoconiosis. Eased on data pre sented in Table 11. treatment, it seems to be preferable to pre sent the facts as simply as possible, to gether with the precautions to be kept in mind in studying them, and to emphasize that the principal use of these data is to show tile degree of improvement in health to be expected in the future if dust forma tion and dust dispersal are brought under control in these and in similar industries. Methods of Dust Control After the physician and engineer have learned by observation and experimentation what kinds of dust arc harmful and in what concentrations, it is the function of the en gineer to evaluate the hazard in a particular industry, plant, or mine and devise measures for its elimination. The first step is to be come thoroughly familiar with the industry being studied to determine the dusty occu pations, the number of persons in each, and the various activities and time devoted to each activity in any one occupation." The amount of harmful dust created by various activities can he determined by tak ing samples of the atmosphere in their vicin ity and counting and identifying the dust particles. Sampling of abris.aJ$o a means of checking the efficiency of any control meas ures that may be adopted. Several devices arc available for collect ing and counting dust samples. The irn- pingcr, however, is the instrument used most frequently in the United States. The Bureau of Mines and the Public Health Service have issued publications describing the. method of sampling dust by the impinger (as well as by other methods) and pro cedures for counting ar.d identifying the particles." . B Dust sampling is complicated by tiie fact that air dustiness fluctuates rapidly from moment to moment. A single dust count rep resents only the amount of dust in the at mosphere at the time and place of sampling and gives no indication o: the average ex posure of the worker over a period of years, especially if he lias not worked continuously at one job. The ultimate lung injury that he may suffer will depend upon the intej grated effect of the dust over a long period.' A proper measure of dust exposure re quires a picture of the variations in dusti ness. The best procedure is to determine the dustiness during different stages ot an operation and, with the aid of a time stud;. break down the worker's day according t the time spent in each step; from these da a the average dust exposure c: the worker ca be calculated. Drilling.--Experience m South with new methods of sampling have rc' <j`^||< that more dust is produced by rock <n than liar; Slating c tected !i> ot contrt the prev by the fa remained higher ai those wlu the execs has heen of time s; Until r> for blasu dust or ai other tha operated ? dust, hut mining po more cs'-ci producers especially jackhamnv compresset in coal or Blasting. dence of si the early p in South Gf the rod dust but to blasting, an varying am <*uced by b feting the quantities o !f e of wl *he mine aii ^entilatii Sh 01'dinf/ ^Ida., slurb rdationship (b mm ress Mutiny Section 541 Table 12.-- Period W orked at Face by F irst-S tag e Silicotics Average Number Job Number of of Years Men Shovelers' helpers (bruno 6.8 8 8.4 438 Drillers' helpers (dummies) 8.4 79 Trackmen.......................... 9.8 52 Roof trimmers................... 11.3 26 Average Number Job Number of of Years .Men Machinemen (drillers). . . 11.4 348 11 5 24 15 8 21 Ground bosses................. 19.0 54 rid duration of dust exposure oconiosis. Based on data pre- rev s the instrument used most m Jnitcd States. The Bureau and tile Public Health Service cd publications describing- the sampling dust by the impinger - by other methods) and pror counting and identifying the pling is complicated by'the fact istiness fluctuates rapidly from moment. A single dust count rep the amount of dust in the at- the time and place of sampling no indication of the average v ite worker over a period of years, f he lias not worked continuously . The ultimate lung injury that .tier will depend upon the me et of the dust over a long period.' measure of dust exposure recturc of the variations in dusti- best procedure is to determine ss during different stages of .ml, with the aid of a time study. :t the worker's day according 10 out in each step; from these da-1 : dust exposure of the worker ca-'. .d. --Experience ,,, _So_u_t_h A fri'--1. vthods o f sainpiing have revetde0 oust is '.reduced by rock dm ' than had been suspected, the difference con sisting entirely of dust too fine to be de tected by the older methods. The importance of control of drilling dust as a measure of the prevention of silicosis is demonstrated by the fact that the incidence of silicosis has .remained consistently and considerably `higher among machine drillers than among 'those who have never worked machines, and -the excess incidence among machine drillers has been in direct proportion to the amount of time spent upon rock drilling. Until relatively recently drilling of holes for blasting was a negligible producer of dust or air dustiness in coal mines especially other than anthracite mines. The handoperated auger drill produces very little fine dust, but with the extension of mechanized mining power drills are becoming more and more essential and some of them are heavy Producers of finely divided dust; this iespecially true of reciprocating drills of the jackhammer type drilling dry and using impressed air in the clearing of holes cither m coal or in roof or floor material. Blasting.--The exceptionally heavy inci dence of silicosis among rock drill miners in Jbe early period of the gold-mining industry m South Africa" was due to the exposure f the rock-drill miner not only to drilling dust but to high concentrations of dust from masting, and frequently to the inhalation oi ^O'ing amounts of the irritant fumes pronnced hy Masting, owing to the methods 0f . ^MitWr-tiien m-uyt.--fjlns-tTOg produces large quantities vcry fim. dust, the finest frac- hfms of winch tend to remain suspended in r* n' iuc air tor a long time, unless removed vcntilr.tinn. i M'Ofrif',., it M u * ' k i n o .-- in the Pichcr, study. " it wn> dii'fViiH to *ho\v the ^linn.i.jp the <Imics nt the men 1C silicosis because of frequent change of oc cupation. All examined were divided into two groups--those exposed to large amounts of dust (those employed at the face) and those exposed to relatively small amounts (those away from the face). In the order of exposure to the dust hazard, the men at the face included shovclers' helpers, shovclcrs, drill helpers, machinemen, trackmen, roof trimmers, powdermen, shove! bosses, and ground bosses. According to analysis of the occupations of face workers the hazard was greater for shovclcrs' helpers arid shovclcrs than for machinemen if length of time re quired to produce first-stage silicosis is a criterion. It is noted from table 13 that the average number of years worked by shovcl ers' helpers and shovclers was 6.S and 8.4 years, respectively, while that for machinemen was 11.4 years. l.oading and Hauling.--Under some con ditions hand loading of coal throws into the air of the working place considerable quan tities of dust, but the amount is about onctentlt that caused by some types of mechan ical loading. The greatly increased occur rence oi dust from mechanical loading is due not only to the stirring of the dust into the air by the loading machines themselves but also to the greater rapidity of breaking down and taking coal from the face regions which increases other dust-producing proc esses. especially blasting, cutting, and haul ing." Poorly constructed or poorly maintained pit cars or over-topping of coal in cars al lows fall off or fine material to sift through to the tracks to be ground under the wheels of rolling equipment or the hoofs of mules and then to he thrown into the air hy -peed- cars or shutfline nudes or men.-' 2i>tli .\uiioitai Saictv Congress W here conveyors (either the sinker or belt type) arc used they lorn: potential sources of dust clouds at the points where the coal is dropped or thrown which occurs at the discharge ends only. Also, where conveyors are used conditions at the face differ from those experienced with the older methods of working in that the miners are closer together, there is a tendency with the more systematic working for a larger number of the men to perform dust-raising operations at the same time, and the air speed at the faces is higher." These condi tions, if not controlled, tend to increase the dust exposure to the face workers. Machine coal cutting.--When coal-cutting machines came into the picture early In the present century to supersede in large part both hand cutting and blasting oft the solid, the really heavy producer of coal dust that the worker has had to endure was at hand, and this was especially true of the chain machines operated by electricity. Top cut ting is the worst offender in so far as im pregnating the air with dust is concerned, shearing occupies an intermediate position, and undercutting is the least offensive in this respect. However, undercutting ma chines under some conditions (such as cut ting dry in friable coal with dull bite in a confined place with little or no circulating air) may produce air dustiness so dense as to reduce visibility almost to zero with available types of mine lighting and to cause between 100,000,000 and 500,000,000 (or even more) dust particles to be carried per cubic foot of air of the face region." Methods of Control The principal measures for controlling dust in mining operations are ventilation, wet methods, proper blasting practice, the use of personal respiratory protection, and physical examination. Ventilation.--The more or less generallyaccepted conclusion that coal miners suffer less from miners' consumption than metal miners, who either die early in life or are incapacitated in middle age, is due almost entirely to the superior working conditions in coal mines as a result chiefly of ventila tion. Approximately in order of their impor- t a n c i the-main' features that affect air in metal mines are ( 1) movement, (2) tempera ture, (3) relative humidity, (4) gases, and I '.5) dusts, In coal mines the order of w I ...iigh tuc arm -tccl 1 portance woeid probably be fl) movement" ' a: tile ia (2) gases, (3) dusts, (4) relative ltumidhv' j ,'|;<d to die itrtll or and (5) temperature.'1 ',io the back tad of The matter of movement of air from the surface, through the working faces or places, and then back to the surface is by j]| means the most important consideration n effecting adequate ventilation of mines and in protecting the health and forwarding and maintaining the working efficiency of |f,e underground workers. If adequate quantities of pure air are directed to the places where men work, most of the requirements of health and many of the demands of safety will be well served." die operating ti' jjowii'k' position, and I gi (lie hole being driller ^roping is aliened rough tlie drill steel rough die drill steel {creases. Mining offic oxiduded that such a probably facilitating r< ji the cuttings irom t fble for entrapping fi K into the air durir joently they have devo Ventilation probably is the most effective csigning drills that ( dust-control measure although under some practical air leakage tl conditions it ranks second to wet methods. and have established rt Where ventilation can be applied effectively, ti such drills. Canada dust can be removed from the air or its con ork along this line, centration can be so diluted as to render it almost harmless." ate that such drills a face about one-fourth IVet methods.--As dry drilling is the dustiest operation in mining, wet drilling will tjoo of corresponding "dustless-hcau" icature keep air dustiness within safe limits if used The results of this with care and judgment in collaring wet, using plenty of clean, dirt-free water, and nators can reduce du siting from drilling keeping the drills in good repair with ade ter flow through tip quate regulation of the proportion of water increasing water press and compressed air flowing through the drill ,nter tubes of larger steel." .-< Tests also have her In tests by the Bureau of Mines* the dust } Bureau of Mines" on concentration in the air during actual drill graying water along t ing decreased as the water flow through the steel compared with t drill increased. The water flows for stopers drilling practice. The was 0 to 3 gallons per minute, and that for a? water along the ou drifters from 0 to 1.02 gallons per minute. should not take the The rate of decrease for stoper drills was drilling. However, if : greater for water flows from 0 to 1.3 gal by which the device i lons per minute than for higher water flows. of any inclination, it The rate of decrease for drifter drills was sMuable accessory to : similar to that for stoper drills at cor collaring and drilling responding water flows and rather constant bdt Tests show tha; for water flows' of 0 to 1.02 gal vis of dust is thrown into minute. ibee in drilling the fl The results of this study shows *1*** water flow through the drills was increas the dust concentrations in the air decreaS but they do not show whether the decree was caused directly by the increased wa flow, by some condition influenced by ,van , tion in water flow, or by a combination . Wet drilling standai * ^'cw York State i fosses of rock. The i i" Class 11 rock '"W 10 ptr cent fr *raJ, which include filiation, are quoted these factors. In most pneumatic rock drills air Pa}- : h "Wet drllhrig~5fi application of wa .1/ iniiuj Section 543 is-r the order of in,, be ( 1) movement, relative humidity, :it of air from the vorking faces or ::e surface is by all tt consideration io tion of nines and nd forwarding and efficiency of the adequate quantities 0 the places where : requirements of demands of safety the most effective .ough under some 1 to wet methods, applied effectively, n. the air or its conted as to render it y v...uinz is the r.g, wet drilling will safe limits if used in collaring wet. -t-free water, and i repair with adeoportion or water ; through the drill fiugh the drill steel with the water. Ordi- hole in the hollow drill steel to the bottom Sly some of the high-pressure air sup- of the drill hole. The central hole in the j to the drill for its operation escapes steel shall not be less than A* diameter. , |f T the back end of the drill steel, even2. "The water flow shall be maintained &beo the operating throttle is not in thceontinuously whenever the drill is in opera ^Sowing position, and travels up to the facetion, including the period of collaring or (he hole being drilled. The amount of air starting the drill hole. The valve in the `aping is affected by the water flow water line shall be of such design that it has. through the drill steel; as the water flow only two fixed positions, namely, dosed and -^trough the drill steel increases the air flow completely open. Six months after date of "decreases. Mining officials in South Africa approval, all wet drills shall be equipped `'concluded that such air leakage, although with a combination air throttle and water robably facilitating removal by the water valve of such design that the required rate i#f the cuttings from the hole, was respon of water flow through the drill steel will be sible for entrapping fine dust and blowing insured whenever the air throttle is in the 3 into the air during drilling." Conse- operating positions, half speed as well as ^qoently they have devoted much attention to full speed. 'designing drills that permit the minimum practical air leakage through the drill steel 3. "The water shall be clean and bacteria free and shall be delivered to the drills under and have established regulations on the use it such drills. Canada is also doing much pressure from an adequate source of supply. Portable water tanks for individual drills work along this line, and recent reports State that such drills are practical and pro- shall not be used unless approved by the In dustrial Commissioner. .duce about one-fourth the dust concentra tion of corresponding drills without the "Wet drilling in Class II rock in confined -"dustless-head" features." areas shall be used with mechanical ventila tion, or in confined areas under decking by- . The results of this study show that op natural ventilation, if approved by the Indus erators can reduce dust concentrations re trial Commissioner and subject to the fol sulting from drilling by increasing the lowing provisions: eater flow through the drill steel, either by i rasing water pressure or by the use of 1. "The rock surfaces for a distance of 30 feet from the heading or other drilling *ater tubes of larger inside diameter. area shall he maintained in a damp condi i Mines5 the du4 urine a::-;ai drill- flow through t flows ic: stopers nute, and that for aliens per minale stoper c:-ills w1* rom 0 lo 1.3 S'-igher ws:er floe'driiter i rills ' ' J` er drill: it cor,d rather ceniairi 1.02 i l Arts P ' Tests also have been conducted by the Bureau of Mines" on the effectiveness of praying water along the outside of the drill letl compared with that of standard wetdrilling practice. The tests show that spray ing water along the outside of the drill steel bould not take the place of regular wet dnlling. However, it a method is developed which the device may be used on holes 01 any inclination, it might prove to be a raluable accessory to regular wet drilling in " Haring and drilling the first 2 feet of a Tests show that the greatest amount `I dust is thrown into the air of a working 'iCr in drilling tile first 2 .f eet of a hole." tion. 2. "Hand-held drills (maximum piston bore, 3") minimum rate of water flow through drill steel, 0.75 gallon per minute; maximum rate of air flow through drill steel at full speed, 2.0 cubic feet per min ute: maximum rate of air flow through the drill steel at hali-speed operation, 1.0 cubicfoot per minute; minimum rate of general ventilation in the drilling area. 500 cubic feet per minute per drill and shall be in creased if found upon tests by the Industrial Commissioner that the dust concentration is not in accordance with the requirements of the Code. l y show:; that * '.Is way ricreale0 the air 2rcreaso.thcr the dec: C i `c : increa;id wa',: hucnccd varie; :v comb-ration >: drilling standards have been adopted C'Cw York State ior drilling in various u*'*' 0I" rock. The requirements for dritl,'J " Class M rock (rock containing more "an 10 per cent free silica) In confined '.S'.' "d'lci'. include the use oi mechanical --hlation. are quoted below." 3. "Drifter-mounted and wagon-mounted drills (maximum piston bore, 4") minimum rate of general ventilation per drill in the drilling area, as shown in the table 'Limita tions in Air and Water Flow Through Steel.' 4. "In the case of positive-prcs>ure v..n- ^ e t drilling shall mean the rnminu- tilatinn. the air must be well distributed aPnhcation of water through tin- central ovi-r tiie drilling and must n n create drafts 544 29th Xatianaf Safety Congress at the various drilling positions, in a man ner satis factory to the Industrial Commis sioner. The intake tor the ventilating sys tem must be located at a point free from contamination with dust or provided with an efficient filter. 5. "In the case of exhaust ventilation, the location of the intake pipe or pipes must be such as to insure the removal of air from the entire drilling area in a manner satis factory to the Industrial Commissioner. 6. "The required ventilation may be ob tained by means of a recirculating air-clean ing apparatus provided the dust concentra tion in the air at the breathing zone of the drill operators is maintained at a level below that required in Rule 33-2.3 and the appa ratus is otherwise acceptable to the Indus trial Commissioner. 7. "The above rates of ventilation shall he increased whenever necessary to reduce dust concentration to the amount permitted hv Rule .-2.3." Proper blasting practice.--Methods of controlling dust and fumes in mines by proper blasting practice have been deter mined by members of the Bureau of Mines staff by observation and experiment.*' * If at all feasible, blasting should be done at the end of the working shift or on an off shift, and the dust- and gas-laden air should be removed nr thoroughly diluted before the men return to work. Ventilation is an es sential agency in cleansing the air where blasting has been done. Results of investi gations by the Bureau ot Mines" show settling rate of dust a ftjr blasting under the following conditions: 1. The atmosphere was bratticed oft for 3 hours while the dust samples were being taken. In this period, under these conditions, the dust concentration dropped from ap proximately 5,000 million particles per cubic foot to 50 million particles per cubic foot. 2. The atmosphere was bratticed off until ~26 minutes after blasting when the ratticc was raised and natural ventilation (which was virtually negligible except for eddy currents was allowed to dilute the dustladen air. It required 2 hours and 20 min utes after blasting for the dust concentra tion to drop from approximately 5.000 mil lion particles per cubic foot to 50 million particles per cubic foot, and 2 hours and 50 minutes to drop to 15 million particles per cubic foot. 3. The atmosphere was bratticed off untl| jr ; 37 minutes after blasting, when the brattice was raised and 10-inch canvas tubing n. stalled to about 50 feet front the face \t In 46 minutes after blasting, about 1,000 cubic doi'' feet of air per minute was forced into the bMi face. It required 66 minutes after blasting -i!! mfoirlliothne padrutsictlecsopnecrencturabtiiconfootot, adnrdop70tomi5n0 ,:O,idl.'0 utes to drop to 15 million particles per cubic mctii' foot. m luc The accompanying tabic shows the time, in minutes, required for the dust concentra temr tion to drop from $25 million particles per now cubic foot to SO million and to 15 million the i particles per cubic foot under the three dif and ' ferent conditions: and . ns [ Time, in minutes, to knee drop from 825,000,000 lust Ventilating particles per cubic foot air. i Condition to-- :o in No ventilation........... 121 lSl know Natural ventilation.. . 105 135 brm Mechanical ventilation 20 24 ifcem: lam . In addition, the place (walls, floor, roof Ifiulf or top, and timbers) should be wetted $ ; thoroughly before blasting is done, and a hve water blast should be used during and after lave the blasting. The region should be wetted ns thoroughly when the men return to the face M region after blasting, and the muck pile irtu should be kept well wetted at all times liiKC while it is loaded out, as the water not only >!orir lays the dust but also either absorbs or |, otherwise aids in diluting or eliminating fv harmful or poisonous gases that folio? ethi blasting and that usually cling to the blasted 'fact material. Tests" on the effectiveness of a spray- of lost water mist in reducing the concentration o dust in the air after blasting and during 411, mucking of the blasted material were iiine ducted in three headings in medium bard r*or hard rock. The use of the spray appar^ - Tlu made it possible to reduce the c?,lCcnV? r of dust gcneraied and thrown >h during blasting more than 99 per cen ^ ^ the amount present when the spray " ? p used. Dust dissemination during n,j>cfoi* u*"L of material sprayed several hours '-'It; mduurcinkgingshwoavselinogeguonf wmasatemriualch 110c oUgfclf h sprinkled just before and during' ^ ^ 0f > and, of course, the dust present i** either the spray or the sprinkling m . M iilny ScctUm 545 ' than " the mucking hmi been done iV lc JrrIn general, the larger the quantity ol ex- . (jve n;ed. the more finely divided the nTjted material, the more heavily the air vjj *. impregnated with dust and smoke. *\j (),(. greater will be the quantity of Ssonotts gases left at the place; hence, Jnethods should be used that will tend to jfduce the quantity of explosives used and 0f rases ami dust produced. In this con- peetion it "ill be found that the use of jonmitt? or of some types of blasting plugs a, available will confine more definitely the explosive, hence, increase its efficiency d reduce the quantity of explosive used and also reduce the amount of poisonous ps produced and possibly reduce the vio- joict of the blast and its tendency to raise Just and disseminate it into the surrounding air. It would be well for users of explosives la investigate types of explosives that are known to give oft minimum quantities of .harmful gases on detonation and to use then; also, the discontinuance of the use of fuse and the substitution of electric blasting trould aid in reducing tltc amount of poison- utts gases from blasting. Explosives that have been held in storage too long or that are been stored under unfavorable condi- 10ns as to moisture, temperature, etc., are 5tcly to give off maximum quantities of (armful gases, if they detonate at all; fence, utmost care should lie taken in the goring of explosives to sec that they are mt held too long before being used. I'i'rxotttil rc\if'irti:.>r -- This nctltod of control of air dustiness is unsat isfactory in underground mining except tor temporary u.-e in emergencies. Although 'Ian respirators give adequate protection l Against dust, they afford the wearer essen- tally no protection against :cx:c or asphvx- a,mg gases, and are too cumbersome and ^comfortable for constant wear. The Bureau of Mines has established a diedule of minimum requirements for 'erhanical respirators, one type of which is or protection against dust generated by dis- '^gration as in drilling and blasting, bout 30 respirators have 1run approved `r-'lr this schedule. ,'.fijujiiiut:oii.r--,y.bough strictly h iking physical exam ination is r.ot a dust- -- trol measure, it is an im r;r:a n t m eans of < ernuijin:v :c c.ucacv methods cm- ploycd to reduce the dust hazard. If work ers exposed to dust are examined period ically increased Incidence of respiratory disease can be discovered and measures taken to reduce the amount of dust in the air or remove any affected workers to a less hazardous environment. _ In South Africa all white applicants for underground work arc examined and certi fied to be physically fit and free ut any dis ease of the respiratory organs and then re examined every 6 months to determine and report all cases of simple silicosis, tubercu losis with silicosis, and simple tuberculosis that may have developed. In this way com parable records can be obtained for measur ing the degree of pqpumoconiosis and tiie extent of impairment of working capacity among employees from year to year. Com parable records will not be obiained unless periodic examinations are conducted in a standardized way, preferably by a permanent medical board composed of physicians spe cially trained and having adequate experi ence in the diagnosis of rulmonary diseases. Summary 1. The principal pulmonary diseases to which the miner is subject arc bronchitis, influenza and pneumonia, pulmonary tuber culosis, amhracosilicosis, and silicosis. 2. Statistics indicate that much higher morbidity and death rates from pulmonary diseases arc experienced in dusty than in nondusty industries, especially where silica dust is used or produced. 3. Investigations by the Public Health Service reveal that hard-coal miners suffer a high mortality rate from influenza and pneumonia not only during influenza epi demics but at other times a- well. In 9)523 and 1906-25 influenza and pneumonia were responsible for 40 per cent of the total deaths among hard-coal miners compared with 25 per cent among malts at ages 15 to 65 who were engaged in purmits other than coal mining. Six per cent of hard-coal miners liad pulmonary tuberculosis com pared with 2 per cent in il-.c aduit male population of the* United Slates. The rate for metal miners is still higher. 4. Anthracosilicosis was r'ound in about 23 per cent of 2.711 employees of three anthracite mining companies studied hy the United States Public Health Service in 1035. tUl v M I?-*' ifs f l M 54o 29th National Safety Congress About 03 per cent of those having anthracosilicosis showed evidence of disability, compared with less than 10 per cent in the control group. Moderate and marked de grees of disability handicapped approxi mately 21 per cent of those with anthracosilicosis compared with less than 2 per cent of the men serving as controls. 5. The occupational groups in anthracite mining, arrayed by the Public Health Serv ice according to extent of physical impair ment, are ( 1) rock workers, (2) regular miners, (3) all others exposed to more than 100 million dust particles per cubic foot of air, and (4) men in haulageways except rock workers. 6. The principal pulmonary disease in metal mines is silicosis and the chief menace in silicosis is tubercle infection. Apparently silica dust alone increases the liability to pulmonary tuberculosis. Joint studies made by the Actuarial So ciety of America and the Association of Life Insurance Medical Directors" revealed that there were 65 deaths where 6 were expected (about 11 times the expected number) from tulterculosis in 1923-1936 among a group of underground miners, most of whom were employed in inctal mines. Tuberculosis deaths were fourteen times the expected among copper miners, nine times the ex pected among gold and silver miners, and eight and a half times the expected among iron miners. In an earlier study" covering the years 1913-1926, there were 18 times as many deaths as expected among lead and zinc miners. 7. As dust is the greatest contributor to the excessive mortality from pulmonary diseases in the raining industry, the prin cipal rhethod of preventing these diseases is to eliminate as far as possible or reduce to harmless concentrations the dust in the breathing zone of the worker. 8. The aim should be to eliminate the dust entirely from the air breathed. Where this is not always feasible it may be possible to reduce the dust to a concentration that will not cause disability during a working life time. 9. Analysis of data collected by the Pub lic Health Service to determine safe limits of dust exposure indicate that employment in an atmosphere containing less than 50 million dust particles per cubic foot pro duces a negligible number of cases of sili cosis when the quartz content of the hum ,. ies than 3 per cent; when the silica con l Coi>> tent is about 13 per cent 10 to 1? milli 8u particles appears to be a safe limit. J. Coll .1 ol 10. The amount of harmful dust creat by various activities in mining can I* de I0JJ-.M termined by sampling the atmosphere it their vicinity and counting and idemifyin: the dust particles. Sampling of air is also i means of checking the efficiency of dust con. trol measures. J. Colli j^cioni vt c Occur* oibi: *c tHi, i*i>- 11. The impinger is the dust-sampling ,,. Strumem used most frequently in the ITtiied States. i. Rrun /oiled I Office ?,< Heal ui-osure 12. The dustiest operations in mining arc i abtic He dry drilling, blasting of dry rock or ore. 4. Sayer shoveling or mucking, loading and haulage, j>. and A and machine coal cutting. kmonic M lana. Kat 13. The principal measures for controlling the ill effects of dust in mining operationare ventilation, wet methods, proper blast ing practice, the use of persona! respiratory protection, and physical examination of workers. 14. The efficiency of these measures In the reduction of the incidence of dust diseases is attested by the experience itt the mines of South Africa where among the whole body of miners the liability to contract silicosis in 1936-37 was less by 65 per cent than it wa* in 1920-3J. Among the "new Rand miners who entered the industry by way of initial examination since 1916 and who have bevf cxjiosed solely to the progressively improv ing occupational conditions that have ob tained since that date, the liability to con tract silicosis was less by 87 per -cent than the similar liability among all miners work 'yw JO. -'JJ, JO jr Dubli :ul Min. Decern; L 1919-20* L Coil' Health, f 'UiL Hj 1 Sen. W'i *:i<rculo> v " 5.257 10. fifficAbraco-.'* -ted St: 11. Unj nary L .\ - Ote Mil 15.18 p^ .12. H a rr /Cum pli -o il of ing for an equal period in 1920-23. The Roi*- "new Rand miners" constituted 77 per err. j/*****tn:c CR of all working miners examined. '-292. Conclusion flic mortality and morbidity iron: pcinonary diseases arc cxcessive-fo-the nn!i_ ndustry as a result of expo-tire to huT* tmounts of dust in the air breathed. There fore, control of the dust hazard is cecei^ l ;o prevent these diseases. No >incle sc*50* ; ji control is applicable to all du?i>* Lions and processes, therefore, all the ^ of prevention mu>t be practiced r #u* nroblet^ I Mining Section 54 7 >f i. i. -c * 'ls can- ;>S b- niieii ' K r on. ulat. roitiia raiiooi bU* iratotj on o' - in iW lisa* .incs oi Me ba!; icosis u n it nine.. . inits .ive Ixn imfn'-. nve of. 10 tie.m tii`- oiV- Tixper k : REFERENCES f Mij Edgar L. O ccupation! D ust Dis*.1* . g u||. 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