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TRANSACTIONS 29th NATIONAL SAFETY -CONGRESS T>d h ^4 t4i d'-s* GENERAL AND INDUSTRIAL SESSIONS CHICAGO OCTOBER 7-11 , 1940 -^ t NATIONAL SAFETY COUNCIL, INC 20 North Wacker Drive, Chicago Copyright. H40, National Safety Council, Inc. Printeo in the U. S. A. I* o< Contents :al Safety Congress iv Council, Octol)or . Volume I contains of the various In* me II contains the icrcial Vehicle, the me Safety Sessions. all industrial meni.) members who are 'essions it contains, may obtain Volume dvantageous to dis:os to the individual their organizations, iformation the vol:tion programs. The .iard reference matnav be obtained as. 2 each; 11 or more me II may be had at cord of the proeecdaddresscs and many > delete extraneous rtions. and empham promoting effee:U prevention measwhat abridged wr it- vaiue to the stu- in achieving more Phe original mamircnce. if desired, in ,'ongresses. >eeks to cli are not pertinent v be contrary to the ; ccept responsibility papers presented or JNC1L, Inc. Council Officers and Directors........................................ 4 Council Purposes and Program......................................... 9 Annual Meeting of Members............................................. 11- Annual Banquet.................................................................... 27 General Subject Sessions-- Agricultural Safety..................................................... 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 Nursing................... 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 Belts..................................................................... 245 Safety Supervisors........................................................ 253 Safety Training ............................................................ 261 Visual Education......................... 277 Aeronautical Section............................................................ 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 Section....................................................................... 497 Paper and Pulp Section........................................................ 549 Petroleum Section.................................................................591 Power Press Section...............................................................625 Public Utilities Section........................................................ 635 Refrigeration Section.......................................................... 659 Rubber Section....................................................................... 671 Steam Railroad Section........................................................ 697 ih^Sccticft T'..................................................... 723 Wood Products Section........................................................ 739 Safety Exposition Exhibitors........................................... 743 Index .... 749 ?<Zi v--- IT ,? .? ,? e S 'P 9 S S P i? g > i> w i no 29th SatiomU Safety Coiu/rcss of prompt and continuous delivery of essen tial weapons of defense we must not only train new workers and retrain older work ers. but we must restrain accidents, fritter away our supply of skilled hands producing these weapons. Maximum Allowable Concentrations of Dangerous Industrial Dusts and Gases By ALICE HAMILTON, M.D. Medical Consultant to the U. S. Division of Labor Standards, Washington, D. C. I have been asked to make a brief sum mary of our present-day knowledge with re gard to dangerous degrees of air pollution from gases, vapors, dusts and fumes, and the data which have been secured so tar as to the maximum allowable concentration winch can be assumed to be within safe lim its. below the danger point. A few of the dangerous dusts and vapors have been stud ied intensively enough to afford us fairly full data on which to establish sucii standards, but only a few, and even with regard to them our knowledge is not complete, and it would be a great mistake to embody in legal regulations the standards which we arc at present tentatively recommending, for it is certain that, as our knowledge increases through investigations in this field, wc shall have to change our figures. I believe that the State departments of labor or of health which have adopted standards of allowable concentrations regard them as advisory only, and that is right. 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 Lcgge, who used the procedure since generally adopted; that i, 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, it tite amount of lead were kept under 0.5 mg. ;cr cubic meter of air, there would be no serious plumbism, no palsy or encephalopathy and only rarely colic. This amount, you set; was not to be taken as safe, only as free from serious danger. In 1953 our own Pu^ lie Health Service concluded that the amount of lead dust or fumes in the air should be kept 0.15 mg. per cubic meter for safety. This was on the basis of an investi gation of a storage battery plant, and a sickness study of 2,303 men employed there. For "prolonged exposure," the figure mat; it seems, be still lower, for some cases were found which had developed even at 12 mg. I believe the next important contribution in this field was made by the Benzol Corot mittcc of the National Safety Council,* which, as you all remember, established KD parts per million as the maximum allowable concentration for benzol. That figure stfi stands, though wc have a good deal of *' dcncc that it is too high. You arc probably familiar with two remarkable reports on in dustrial benzol poisoning which appeared B 1939; one from the Massachusetts State De partment of Labor on benzol in the manu facture of shoes; the other from the York State Department, on benzol in roto gravure printing. In both studies cases were discovered that had developed after * posurc to concentrations below 100 ppm. 3* a result, Dr. Francis Hunter of Boston de clared that, "It is doubtful whether any 6centration of benzene greater than ro & safe over a long period of time." The American Standards Association ^ had tor some years a committee on this s Americaa Standards Association Committee 5ubstao.ee Carbon, monoxide Benzol Carbon disulphide Hydrogen sulphide s 1 ! , ! 00 400 100 20 20 Not over 8 hours daily -8- - ................................ Governmental Safety Service m Industry 111 -cstrain accidents, w!>ich supply of skilled hands :pon$. Dangerous Washington, D. C. :ic. This amount, you set, :cn as safe, only as fret or. In 1933 our own Pubce concluded that the ust or fumes in the air 5 mg. per cubic meter for :i the basis of an investi.cc battery plant, and a '.503 men employed there, .'tosurc," the figure must, .wcr. for some cases were developed even at 12 mg. xt important contribution rude by the Benzol ComNational Safety Council remember, established 100 a< the maximum allowable benzol. That figure stiD c have a good deal of evido high. You are probably i remarkable reports cmiiv isoning which appeared in Massachusetts State Dr- on benzol the manethe other :'f,m the Xtt v.r.cnt. on Ur.zol in rotou iioth studies cases were iad developed after exrations below i00 ppm. A* .cis Hunter c: Boston d<loubtfui whether any con vene greater than zero & period of time." Standards As-ociation b* a committee on this^u- mitfee ef exposure ir 8 hours dsiiti. t . >* Suggested Standards yfor Illinois and Massachusetts Parts per Million Milligrams Sr QjbicMefer Illinois Mass. Illinois Mass. Substance Ammonia 50 100 Aniline 55 Benzol feed 75 Carbon tetrachloride lOO ,, 75 100. Chlorine 0.35 1.0 Chloronaphfhalenes 5 1105 Chlorodipbenyls 5 1.0 Chromic acid 1.0 0.1 Gasoline IOOO 1000 Glycols 25 Hydrochloric acid 10 Hydrocyanic acid 10 10 Hydrq^looric acid 3 3 Lead 1.5 1.5 Mercury 1.5 1.5 Methyl alcohol 100 200 Nitrogen oxides 10 10 Nitrobenzol 5. Ozone 1 Phosgene 1 Phosphine 2 Sulphur dioxide 10 10 Tetfachloretfcane lOO 200 Tetrachlorethylene lOO 200 Tricblorefbylene 100 200 Toluol 75 200 Turpentine j 500 200 Xylol 100 200 Zinc oxide 150 15 Jct, composed of industrial physicians, ven tilation engineers, industrial insurance car eers and toxicologists, who arc trying to set UP standards for use in industrySo tar v.'c have dealt conclusively only with two gases and two volatile solvents. S&iQs^Slcrsxide - ar.d hydrogen sulphide. zoi and carbon disulphide. The limits adopted tor the present are shown cr. the Accompanying chart. Benzol stands at 100 PPm.. c.tiefiy because of the insistence of our usurar.ce members that this is an ideal that can be realized practically while a more rigid standard would be rejected, and we should be left with no standard a: all. My self, I am always willing to accept half a loai rather than no bread, but Manfred Bowditch. of the Massachusetts Eurcau of Occupational Hygiene, is unwilling to go higher than 73 ppm., and Yanacil Hender son. of Yale, enters an emphatic protest against 100 ppm., saying that it 20 ppm. is feasible for hydrogen sulphide and carbon disulphide, he can see no reason why it is \; 3 F Jra # 'm t -f! -,v 112 29ih National Safely Congress aniline and Tentsfiue Staodards Adopted By Public Authorities for Maximum Allowable Con centration Of Silica Containing Dusts Authority Millions of Particles perCuFt^fAir ______Free Silica Content : High ; Medium. (National Silicosis Coiner- | Low -roup- We the other c CC14, about more. As : comes chief pharmacolog non-toxic ag fection whic. dustria! poise erace. 1936. Medical Com mittee....... --.............. .............5 --r l0 to20~-j--------------- Difto.&^ioeeringConjmittee...... 5.......-10 to30--t--------------- U 5. Labor Department |- 1936 Division. of Labor j Standards............--.......... r--5------.........15------ r--------------- (NewYork Department^ Labor. 1940---------------------10----------------------------- j---rl00*-- Connecticut Department 1 j of Public Health. 1936.----------5.......... ------- ------------ ------------ California Industrial Acei- , | dent Commission. 1936. --5----------------------- p--50-....... . To pass o field, silicosis fact, so evide that there is agreement arr . amount of du v lions of free : v. a workshop. 1 ;. mg from gase; .. not take fittee; silicosis may. . . from the acu k'affect the dan L-rduSt. felake found: Wisconsin Industrial Com* ! mission. 1932. - -.......---*p--5........ :----- 15...... *--------------- Massachusetts Department: of Labor 6> Industries 1940..... 5--............. 10------ --100 -- (granite) ( 25 .. ' ; foundry ! : Nuisance _________ _______ ...... ____ ___________ Dusts impossible tor benzol. Certainly :: is lo be hoped that ventilation engineering will pro gress to the point where a lower figure than 100 ppm. may be reasonably ck-mamled tor benzol users. The standard for carbon monoxide does not need to be defended. This gas has been exhaustively studied by the Public Health Service, by State bodies, by industry and by loxicotogists in many universities Carbon 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 du Pont Cc--p.inyand the Tubize-Chatiilon Company. When it comes to the other vvoc suh"stnnces I have listed here, we car. :av only that the figures given represent our best judgment at the present moment, hut %ve 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, tetrachlorethane. We know it is the most dangerous of the chlo rinated hydrocarbons used in industry, and we have known since the first world war what its action is on the human body, for it was used by both the Germans and the British in airplane dope, and in both coun tries gave rise to cases of acute yellow atrophy of the liver; but, in spite of* voluminous literature and an impressive number of clinical cases, we nr.d no stance in which the amount of poison in the air was determined. Therefore, the-snandard, ten parts per million, is based on Zangger* statement that this solvent belong; "'iir< silica, running 8dangerous grai . JusJcr centuri JjSeasifof stone c yepf foundry wor ffioi this particul Hatch and Mok ?7tion for the dif? y and other silici ` shown the silic chiefly in the lar particle size dec till it may rer microns, only oi fifth of the per^ microns. This is foundry dust cai chipping, jobs w. the industry kne foundries are th more chipping is If our kno\vle< required to prodi [ tying, this is still what constitutes fins. Here the P: mS much valuabl ^tal investigate 'anS" c have carri and, jn cooperatio s Governmental Safely Service in Industry 113 rt offar r -OW 100- 50 100 25 OUQdrq aissace ->USTS represent our best moment, )mt we ail. is often based on i guess work. Take ppen to be engaged -trachlorethane. \Ve gerous of the chlo-ed in industry, and the first world war human body, for it Germans and the -. and in both couns of acute yellow but. in spite of a and an impressive s, we find no m* -'"t of poiso.vsp.-*^ refore. the standard, based on Zangger's .vent belongs .with atitlin*-' juh nitrobenzene in the most toxic roup. We l,avc little data with regard to the other chlorinated hydrocarbons, except CCU, about which we do know somewhat more. As to the others, our knowledge comes chiefly from the studies made by pharmacologists who sought a relatively jion-toxic agent for cases of hookworm in fection which is not the same thing as in dustrial poisoning from fumes. To pass over to that very controversial /3e!d, silicosis, I need hardly emphasize the fact, so evident in the accompanying charts, that there is still much confusion and little agreement among the authorities as to the amount of dust containing varying propor tions of free silica that may be permitted in a workshop. This is to be expected. Poison ing from gases and fumes, even if slow, docs not take fifteen years in make itself evident; silicosis may. Moreover, other factors, aside front the actual proportion of free silica, aJfect the dangerous character of a given dust. d--:.Take foundry dust, h may be rich in' Tgsllica, running as high as the notoriously .^dangerous granite, yet, while consumption l&has for centuries been the occupational dis please of stone cutters, this has not been true foundry workers. Recent brilliant studies '`of this particular dust, notably the one by ; :r 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, for particles under 2 microns, only one-fifth or even one twentyfifth of the percentage in particles over 10 microns. This is, however, not true of the foundry dun 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 if. towlcdgc of the minimum dose required to produce poisoning needs ainplifyir.g, this * still truer o: our knowledge of what conn rates dangerous dust concentrations. Here :kc Public Health Service is doing much sluablc work. Their two monu-' -^.j-rasHnve`srigations. of the Vermont granhe industry' and of Pennsylvania anthracite mining, h*. v carried us a long way forward, and, in coe rorarion with the 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 to be expected among workers in an establish ment wiicrc there is no special dust hazard, is 4.79 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 iu which a healthy 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 years." General experience shows that the first is at about five million par ticles less than ten microns in diameter; the second is probably at a level not higher than 100 million. At the National Silicosis Conference held iu 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 5 million, the condition may be looked on as permissible. If 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 ot 30 million particles would mean 0.1 times 30 million, or 3 mil lion, good practice: while 30 per cent free silica and 50 million particles would mean 15 million, too much. This formula cannot be applied to a dust with less than 5 per cent silica. Both New York and Massachusetts have made fairly recent studies of tiic foundry industry and oi 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 "0 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 25 per cent: the dust from abrasive -blastcleaning, averaging 70 per cent down to 10 million. Massachusetts allows 25 million for foundries. 10 million for granite stone mills and 5 million for pure silica dust. :"y V?A " 29th National Safety Congress Source of Dust ! Percent of Cuartz Suggested Standard CTree Silica) In Million fertides (Below 10 h)icrccs)per Cable Foot- of Air. Gold Mines, South (fries------ 8866 ttoo 9955-------- -5 to 4.5 million St Chief S The title I A. been "Dcr no other ; democracy ical fashk --90----------- -Under 6 State indu ine everyc at one tim _ 5 to 10 (2 ttioes)' I 2510 35C- - ) Q.5 the role t States an. law" to : year after accidents Granite Cutting, Barre. (Rock.2G5) j--9 to 20 Vermont Dust. Average 55 over and c By one mobile ha method o: Metal Mines. Tri-State Area tawed the it a pria machine, meeting 1 Potteries. West Virgioia.--20 to 50 10,000 ot! ideas and Anthracite Mines. Pennsylvania. ^W&A.I-lX I quartz) --5 to 10 Eock Worker? dust average 35 Subway and Foundation* Drilling. New York City j Less Itsn ito64. 10 Democrat "Democ dustrial s tional pre and error before in industry fit its pr foot the use the d We must not forget that the adoption of great need of careful studies of actual con tion. 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 ditions under which damage from poisons ar.d dusts occurs in industry. It is in out country that 'these studies must be made. The day is past when we could look to Gef manv as the source of knowledge of Indus ( There i f unifor and recu' 1933, but cases have continued to develop, rial' toxicology.- Now that authoritaM&, | - - the taking 14 years now, on an average as against an earlier average of 9J4 years. In ',*ition has passed to us. And this P3.r*,c?\ i method of determining safety limits > 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. -.eans of a combination of experts in se_ ral fields, chemists, ventilation engineer-^ r.d physicians is peculiarly American. * -.her country has made anything like ontributions to this branch of industn hygiene that we have. But we need a S1* all I need not say anything more about the deal more. :t have taken a man's mind. 4 cessary /or me rry certainly p]av, accidents. I am tat my accidents thoM we had not tat difficulties. But 1 . job for them b safety program at ting rid of tbdr Occupational Disease WEDNESDAY MORNING SESSION October 9, 1940 .' The meeting on Occupational Disease. planned as a Panel Discussion, was called ' jo order by the Chairman, Walter S. Paine, Manager, Engineering Department, Aetna Casualty & Surety Company, Hartford, Conn., who presided. union is almost as ,rtsv. fety program, Panel Discussion talization and sid- -"CHAIRMAN PAINE: At every meeting in about the sarur \ * that I have attended in this Congress some n working in vow one Has raised the question of industrial dis- -ale job, he is not This is a subject which has been money and has t .-^maligned in some cases and has been a tan mobilities. His doc* sy on the part of others. This, however, j going to have tt onld not in any way destroy the realities out" The doctor*} 3that are back of the industrial disease prob- be $25, $50 or pot- is going to have ** ' ceks, and there iriS lSj|la'the discussion of this broad problem. ay there. That is 5nPSJme asked the medical profession and rahclaw 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 Brehm, 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. uring the time he is eivc a definite sidi* >ws he is going benefit, he is a to Sftfthe problem will be discussed on an or*Mrly basis. We have assigned as the first -Speaker for each of these subjects one of the aenon this platform. After lie has finished bis preamble, we will ask the members on to go ahead out: and, again- ^ a favor ar.d yon * . the floor to present any question they may bveon the subject. physical ccaditior- r .MWve thiave the tfollowing subjects to Ik- <;- ih.em' do fptil-a.v aaptf ! nro^ram. 1 "Health Hazards in Spray Pairv.^u?ene Walslt. Associate Super* I' T adie< aadCm- [ ^ f Medical Service, International interest thb mom- j harvester Company. Chicago, will open this Spray Painting DR. EUGENE WALSH: Painting is a topic that has received considerable atten tion. There has been an increasing number of hazards imported into the trade. Mot of these have received wide attention, par ticularly in the past few years. It has been incident to the wide use of the spray gun and of liie lacquers, particularly. Many of the solvents and products used in the paint industry have known toxicides. Others are dent satisiaciwttj' s in the experimental stage, so far as u-e and ncl that the Chf j ~fatigue and Its Relation to Occupational so far as their hazards to health are con nan to turn to ^ I This subject will be taken up by ichali of the Pa'P \ ` ^orbert Enzcr, Director of Labors* lad that ti*^ Blount Sinai Hospital, Milwaukee. ^ `1 YThe Toxic Limits of Common Solvent." this pane*- . tj1* subject will be opened up by Dr. a good par: oi* * n E Belknap, of Milwaukee. will be Industrial Processes.'' Dr. Ed- ; Tf also handle this subject, c^kin Affections." This will be handled I $LPf', N- J- Reuter, Dermatologist ` -Philologist, of Milwaukee, Wis. 1 ' ,!l **Ia"nS. hbout,t!.!onCeh of the most importer.-. cupatioual Diseases ' cerned. In the old days of brush or dip <,r flow painting, .-till widely used, solvents of rather low volatility were employed, and the haz ards associated therewith were not as great. However, when we come to the spray gun. particularly in its use in the recently devel oped lacquers, wc come into a host_oEzic-\v solvents. The quantities used per year in lacquers and solvents in the paint indu.'try in the United Stales reach astronomical - r*mor;:ons. Mnnv, main- ton- an- used. 166 29th National Safety Congress 3t In the paints we have the following haz ards: first, the pigments. There has been a growing trend definitely away from lead bearing 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 with. The solvents used are relatively low boiling products which volatilize read ily, 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 oi the lacquers in cludes the driers, such as ethyl lactate or ceilusoive, monomethyl ethers and various other chemical products of known and un known toxicities. Also, there must lie a fiexiiizer 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, we do have some benzol toxicity to be consid ered when xylol is used. Also, when have two substances which are used to nab a paint or lacquer fluid, its toxicity, res^. ing from the combination of the two stances is not usually that of a suttnuti* of the individual toxicities of the tivo. is, if we have two products (A and B), die viewpoint of the panel on this subject, namely ! spray painting ? EDWARD SMITH ( Malleable Co., Buffalo, N. i$ made about spraying - one-plus toxicity, if we wish to use a* . DR. WALSH: Sprayim terminology, and B of one-plus toxicity, is a common procedure. may get a resulting toxicity of three-? largely calcium, it is a re: or something of that nature--just to use* substance. It is irritating : arbitrary form:---------- tree and may be follow, The methods of control are: First, cough. Not infrequently t: substitution of non-toxic products sudi^ aunts in whitewash which we mentioned in getting away from products in them but, c bearing pigments in paints. We are fome* cashing is a matter that is to have alert chemists in the paint indesq week, and perhaps a mon who are alive to this problem. They a done in most industries d: constantly striving and working with tee* ttposure is relatively in: dustrial hygienists and the physicians ia < iazards are not great. veloping non-toxic products, so far as & Likewise, most of the u pigments and solvents arc concerned. T tedures are done in large, Another factor that has been consi&n. That isn't true of some ti_ and is of importance today in redaaq .If.it.is done in closed ro' toxicity* is the mechanical dcvelopmct ^ places with poor aeration, the spray gun. Many years ago, in itj^ itfie process is to consum fancy, no precautions were taken. Tie ii vhme, to have the individ gineers weren't particularly interested manner. Just a simp! A man would spray with one or aacdxr. mechanical dust type re spreading the toxic substances about. Tb&j. / vould be usable if the cxr however, with the development of Bjtf ' "y.length of time. i V, . pressure spray guns, with the devdojoe* of engineering methods of control ofn^t* r y X-Ray Examin and fumes and dusts incident to the we have less toxicity. ROBERT- if. BU: ?Jte Medical Assn., St P If an individual corporation is alert 3* methods by x-ray t serving and controlling the hazards 10 ttme or from year very little toxicity need be encounter*, ojk ./'r5)2ress of bronchia: most processes. This includes, of cour<t*i ; Paint inhalatio: precautionary methods for the when I speak of the industrial hyg'^Jf Would anVALSH: There the engineer's phase of the problem. W m! vver },ur individual is working in a place gineering methods are not feasible t0'* v Ar.?t8enolStS. VqbcJM"* ,dea of makin -%^2`5ct"byx.ray. Th the vapors and toxic products, then th* x'ray are lar dividual must have his respiratory tion to..preven-t inhalation. Most `*J solvents which are use<d ThlmaveVaa ^j ' bt ?. . se*s a[id fibrous i4^etrue'.ho-- action, and their action is by w*>` sorption through the respiratory ing away the fumes is the way ot I have very briefly outlined Paint thJTWhiGh - the ,, * otd not me wnt~*thaPt orcelain industr s another pro! i ^'^-hearing'paim question ? & ; A^ver, for 1 * -- AIRMAN PAINE: Discus*^ .**i2,.4l>SOrt>ed, so carried on from the floor and - ; :.'Vc changes in the Occupational Disease 167 used. Also, >vhen *> > viewpoint 0f the panel. May we proceed show on the x-ray. Most of them are 8, hich are used to ^ s4 ,ts toxicity, r(lsul ation of the two sub. this subject, namely health hazards in Say painting? stopped by the mechanical aids in the nose and upper respiratory tract, that is the hairs, the cilia on the lining of the respiratory that of a summaU tract and, as such, are coughed up, rather cities of the two. feDWARD SMITH (Jewell Alloy & than persisting in the respiratory tract ducts (A and B), A0f ; Malleable Co., Buffalo, N. Y.): No mention we wish to use that .has made about spraying whitewash. However, if one is using paints over a t one-plus toxicity, toxicity of three-pta nature--just to usea^ ' N' control are: First, long period of time, it is conceivable that a ;%.pR. WALSH: Spraying with whitewash chronic bronchitis might result. However, wr'g'.-j common procedure. As whitewash is here one is on thin ice. There are many calcium, it is a ^ribstance. It is irritating relatively innocuous to the respiratory other factors incident to the causation chronic bronchitis that are equally as, of or ee and may be followed by a chronic more, important than the products used in :oxic products such as P^mugh. Not infrequently there are contam* the paints, either the pigments or the sol ting asvay from lead- jhts in whitewash which may have toxic vents. aints. We are fortunate 'products in them but, ordinarily, white* :s in the paint industry "joshing is a matter that is done today, next MR. CARR (Eastman-Kodak Company): ;is problem. They are' gsVeek, and perhaps a month hence. It isn't :d working with the in- |8bne in most industries day after day. The d the physicians mile- ^exposure is relatively infrequent and the In spray painting in rooms, using lead-free gasoline as a solvent, we have noticed as much as 450 parts per million of aromatics, roducts, so far as both ijlttzards are not great :s arc concerned. ^Likewise, most of the whitewashing pro- at has been considered ifttdures are done in large, open, airy rooms. cnee today in reducing r&That isn't true of some tunnels, of course. 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? chanical development of .j{ it is done in closed rooms, tunnels and DR. WALSH: That is a problem, it is ny years ago, in its in ^places with poor aeration, it is advisable, if true. Certain fields of oil, particularly those ns were taken. The en- the process is to consume any length of bearing the naphthionic acid oils do, in their ricularfv interested in it time, to have the individual protected in cracking processes, result in benzol in con cy with one or another, ^Votne manner. Just a simple draft of air or siderable portions, in some instances, in the substances about. Today, mechanical dust type respirator probably gasoline. The straight paraffin oils may re development of lower .would be usable if the exposure is to he of sult in some benzol but not so much. It is a with the development any length of time. factor to be considered. It depends largely .ids of control of vapors upon tlie amount of benzol present. In some incident to the process X-Ray Examinations instances it has been said to run as high as 10 per cent in certain gasolines. That is not 'rporation is alert in ob:ne the hazards present, need be encountered in s includes, of course, the ads for the individual r industrial hygienist and DR. ROBERT M. BURNS (Minnesota State Medical Assn., St. Paul, Minn.): Are there methods by x-ray examination from time to time or from year to year that will show progress of bronchial trouble as a re sult of these paint inhalations ? 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 e of the problem. If w DR. WALSH:" There are those that erties, but they are transitory, largely. rig in a place where en.re not feasible to control c products, then the if his respiratory' protecihalation. Most of the : used have a narcotit ction is by way of ahc lespi'ratory tract. Tals is the way of control dy outlined some of the ou choose to pursue thi? AIXE: Discussion w'^ the floor and also frotf would answer your question in the affirma tive. Most roentgenologists, however, rather scoff at the idea of making a diagnosis of bronchiectasis by x-ray. The shadows which sec in the x-ray are largely those of the blood vessels and fibrous structures of the `ung. I: :s true, however, if an individual is UsinS *-.me paints which bear silica--and ?ne pa.r.: that I did not mention is that used ln the porcelain industry, silica-bearing Pamt--?-ae js another problem. If you are using a silica-bearing paint, you will get the characteristic changes of silicosis. However, for the ordinary pigment, so mle : absorbed, so few of them produce Benzol has developed a chronic toxicity. This particular subject is receiving attention now, but -very little lias 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 possioie, by ordinary" methods. Atleast 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- Progrv-.ivc changes in the lung, they rarely 8 >-* <Zl. *.' * W i&K sfe * '* MzikSsvz mi: 168 29th National Safety Congress tory protection of 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 diluents used in the lacquers which ue atv now employing. The process is very nui^.? the same. \\e are beginning t suspicion. Dr. Ga Company believes There has been some change in the length than, we have thoi of time required to dry these lacquers, butt ' S* aTthe vears x< 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. the constituents are the same as they were^* ^cu_r_a*t-e knowledge W. H. KRAUSE (Allis-Chalmers Mfr? perhaps encourage Company, West Allis, Wis.): There have& _that probably woui been recent changes in regard to the diluent^ ' boo. MR. WALSH: That certainly is a fine arrangement. DR. ALICE HAMILTON1'(Dmsion"or Labor Standards, U. S. Department of Labor, Washington, D. C.): In the Division of Labor Standards in Washington some used in paint. Quite few of the larger oils companies are now-producing hydrogenated* naphtha. These do contain considerable* quantities of benzol and toluol. I wonder if$ ' there had been any experiments made with2** regard to the toxicities? MR GUMMAR vould like to offe: Commercial toluol *** n contain a: benzol. two or three years ago, when I was visit CHAIRMAN P ing automobile plants, I was told they were Benzol Frowned Upon pass on to the next l.-St making a change in their coatings. I wonder ' Relation to Occupa- whether that has proved to be true? They DR. WALSH: I should have mentiont ject will be opener' told me they were substituting synthetic when we were speaking of toxicities of sol^ ? Director of Labors resins tor nitrocellulose and as a solvent vents, that the medical profession from > pitab Milwaukee. were using hydrogenated petroleum prod upon the use of benzol as a solvent or i -3^,'-''' ucts which had very' low volatility. It luent in any proportion. We just don't til ..-^Fatigue and 0 seemed as if that were going to be a revo benzol, regardless of its percentage, fcecat _ *"<..>.*.*.'.* . lution in coating in automobile factories. I it is so easy to get out of hand, and tbi '?DR. NORBERT should like very much to know whether that change has been made. CHAIRMAN PAINE: Can anyone an swer the question of Dr. Hamilton? DR. WALSH: 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 irom 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 chronic effects of its poisoning come on.j slowly and so innocuously, they creep`o on you before you know it. It requires retftd close observation wherever there is benzol or toluol. \ b the morning I g If krel of activity a J Patigue fs a state \ transient character, -'oaderstand it and . So far as the hydrogenated naphthas are| toed .but, so far c concerned, it has been said that the hydra^5 f*bgue is that st venation does not change the chemical st ; *ork which makes turc of the naphthaj and it does not inct toform what may particularly, its toxicity. If it is in relatively ; tOOd Output large quantities, 400 to 500 parts per then there is the problem of the toxici inherent to the hydrogenated naphtha But we would much prefer not to see ; . I* is characteriz 7 ? characterized i-wrestigation by c r^.%} will dal*,, zol at all. ^ 'he strictest t CHAIRMAN PAINE: Dr. Hamihoa j *. C?,30 occupations you wish to say anything else on the sa $ * ^ * direc partment of Labor. It is a beautiful presen tation, and it is worth while tor any of you interested in the paint industry to read it. jeet? 'L.^'nsunce in DR. HAMILTON : I think not. My sl' of the subject is four years old. I thonpfc. ^ theca C*: But as our 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 arc changes in the right direction, in many instances. perhaps very important things had .conL<ii-'Sj ' lighf s1nce~ihcn. Apparently benzol is 5 5$ 2 Werpret the v lurking.. dja_n__ge_r which arises in all ssoortrsts . unexpected ways, especially as we use iw *toiatil0n from hea cracked gasoline than we did before. I/j eg an oc agree that it is something th at' *houJB ;.S^`11 health avoided. '< hy circum- DR. A. L. BROOKS (Fisher Body Di Wc always advise the substitution that defi.- vision, General Motors Corp.): We do quite toluol, when possible, for benzol, by h,ch> und a lot of spray painting. I believe there has think any industrial physician would . been no radical change in the solvents and mg to give a clean bill of health 10 , .couldn'i ?;*** The Occupational Disease 169 di ^ vcr>' ti,c length. `Huers, but lhy were. ' Mig. 'here hive lie dilue^ - larger oil drogenated onsideruble ' wonder if made with mentioned, ties ot sol- on frowns vent or <5- t don't-lie ge. because 5:d, and the " DR. NORBERT EXZER: At ten-thirty come .on so Jfc.the morning I generally have a very low y creep up .`Ykrtl of activity and suffer from fatigue. tiires rather -.'4^Fuigue is a state of bodily ill health, of icre is' any. ./transient character. It is evanescent, as wc '^'aoderstand it and as the term is commonly lanlithas' are* but, so far as industry is concerned. , the hydro- v-t%^ue 15 {bat statc * individual at 'mical struc-' V *work which makes it impossible for him to not increase, in relatively perform what may be considered an average good output. per million. ,c toxicid >htha itself, to see bo* It is characterized by certain symptom'. It n characterized under ideal conditions of nwtstigation by certain objective findings *hich I will elaborate in a moment. miiiton, did m the sub- t. My study i. I though .ad come & :o! is Still* all sorts o ve use mot* fore. I r should ** -titutic-n . but I deej >u!d be ",L, DlU<i In the strictest sense of the term, I supan occupational disease is that condition %Ech can be directly traced to some agent c circumstance in employment which can labeled as the causative factor of 'the diseast But as our horizon widens and our -ept of disease becomes broader, and as ** interpret the word "disease" as it was ^ginally used in the Greek sense, a statc of ]^at*on from health, or dis-ease, then we regard an occupational disease as any of ill health which lias been contribt0 by circumstances of employment. *'lat definition there is hardly a tt^which. under some imaginable statc ^^nairs, couldn't be related to what the is doing. Those arc the two extreme definitions of the term "occupational dis ease." Xow, any disease will produce fatigue. It is almost synonymous that disease limits the output or the capacity for work of the in dividual who iias been affected. What wc must recognize today is that fatigue may also constitute a state of disease. In other words, that wc recognize fatigue as a func tional disorder which must be treated, which must be recognized and corrected, and its causes eliminated. The mechanism of fatigue is grounded in a very complex explanation which is not yet clear, and probably won't be clarified untii a great deal of investigative work has been done. But in the past few years a con siderable amount of investigation has been done, most notably at the Harvard School of Industrial Hygiene under Dr. Dill; 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 hts occupation, without sacrificing any quality of his health. Xow, 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 channel' 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 of 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 of the brain to send impulses to the peripheral muscles so that work may be performed. Xow, monotony of work may he the greatest contributor to fatigue. I use tiiat as an illustration. For example, we found out, in one small investigation, that .jmUyiduals employed at work'which called for dexterity and nimbleness and a high degree of mental alertness fatigued in less than a twenty- vj'Stt*, 3 Wr^Wl 1 .<0* .N. HfiUf: i'ir r; '' ij !)'; i ] sftfcs-v ' If* ,;k ;-;%: &?;\ *&! Ifra :< ^j:? n i: 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 stationary, position, 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. Ex 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 it 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 been able to show in some small investigate* that if it could be arranged that this job could be done in the sitting position, output would be increased and the indivki. - ual would suffer less fatigue. . r*|. It has been shown that, in jobs which? call for a to-and-fro movement behveaf." more or less fixed positions, without mudj^ opportunity to rest, if the period is broken*' hourly or-at hour'and' one-half intervals,? and simple freedom of motion allowed to? get out of the range of what he was doing,rest is instituted and fatigue is relieved. We have been able to show that the appli cation of bathing, in certain kinds of indusi 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 introj. duction we can go on and attempt to answer^- some questions. ' Tests of Fatigue CHAIRMAN PAINE: Are there questions from the floor? This is an inter*?, citing subject. DR. WALSH: I should like to ask *? question in relation to various tests of &: tigue. The psychologists have all had peopk. putting round pegs in square holes and a that sort of thing, rapidity of process*- That is one method that is not my concept of the way to measure fatigue, but it bring*, up one point; namely, the relation of fatiSP* ; to the mental status of the individo^ Again, the psychological yardstick may applied. What is the relationship of the in telligence quotient of the individual to * tigue? Does the person using his n'tr"?^ his work fatigue more readily than one ing physical activity in which no menta ^ tort is .squired? DR. ENZER: If I may restate tion, I think Dr. Walsh really wants o ^ I out whether individuals of low I-Q-> | speak, experience the same phenomena ^ fatigue under the same circumstances individual of high I.Q. DR. WALSH: That is right. . DR. ENZER: I would say he **,.] though that is not generally rccogn'2 ^ BEN JOHANEK (Conno; Wakefield, Mich.): Do you i 0{ this is caused through imp DR. ENZER: We are nc that nutrition plays an imp nervous fatigue because we h certain elements in food that for the integrity of the ccntr: ; tern. But we have been able u preliminary experiments and i veys that, in a general way, f eept in an extreme instance, is but in acute instances it is. \\ . by that? An individual who prived of food for longer t mally accustomed, in other meals are separated by too 1c time; fatigue will be produce that on ourselves. We took early morning until late at i able to show increasing fattgu ...:_We .were also able to she Keirknown, of course--that .tain kinds of food which g - porary relief from fatigue, n' sugars, carbohydrates, and a been done on the proteins of sense that I have tried to 1 this morning, diet is a factor c*use it becomes a disease s' case state induces fatigue. D * state of fatigue if we h. disturbance in the habits of d Factor of Noi: MISS MARY LOU SC SeagTam & Son, Louisville, ** to know the effect of f rfS*rd to fatigue. ** ENZER: Noise is a f demonstrated that objee he way jn a laboratory, : * tested individuals for t r?-enon rate which, as I j ii*i ^Se ^ne> Afterwards, 'vith a sound of r jJ* Aythm and rate, the S J - er we could fatigi: jram and in that way < 5u>j 5.Centcr of the brain, a detract one center fr< to l^at this invest *e*i!d * 'V ra*hcr interest: ire, three, perhaps. 0 . ^btutionally, indivi ter--.- Occupational Disease 171 TOHAXEK (Connor Lumber Co., nav< bt*,' fefSiel'd, Mich.): Do you not think a lot at.thi* >3 this is caused through improper food? p'tion, ^ irR. ENZER: Wc are now recognizing l>e PSat nutrition plays an important part in ^yvous fatigue because we know there are j^s hij elements in food that are important the integrity' of the central nervous sys- *h?ut ** 4 '? broka' l ,nterva|t allowed to gu( We have been able to show in some ^Stninary experiments and from some sur- ArSrtt that, in a general way,-food intake, cxin ^ extreme instance, is not important, : 'y^s doin, ^but in acute instances it is. What do I mean relieved. Iby that? An individual who has been de#ptived of food for longer than he is nor- at the appii. r^mifly accustomed, in other words, if his ;ds of indtis- ^Soeals are separated by too long a period of ^ of fatig^ 4&tuae, fatigue will be produced. We showed individual lllithat on ourselves. We took' no food from ' Those an Nearly morning until late at- night and were occupations] jstrial aspect casual intro-' npt to answer 3&ble to show increasing fatigue. were also able to show--and this is l&t-el] known, of course--that there are cer- kinds of food which give some tera- !j; . Jzrpbcary relief from fatigue, most notably the it'Sidgars, carbohydrates, and a good deal has ;.been done on the proteins of diet. But in the .re there any ?feose that I have tried to lay the subject ;s is an inter-! morning, diet is a factor in fatigue be- ^ginse it becomes a disease state, and a dis- :Yjease state induces fatigue. Diet will produce like to ask'a p^iCstate of fatigue if we have some acute us tests of fa* turbance in the habits of diet. - all had people e holes and all of processes. Factor of Noise :ot my concept e. but 3t brings ation of fatigue the individual rdstick may be .ship of the in.dividual to fa ng his mind in iy than one doh no mental ef- 'V^MISS MARY LOU SCOTT (Jos. E. i , Seagram & Son, Louisville, Ky.j: I would Eke to know the effect of factory noise in regard to fatigue. DR. EXZER: Xoise is a factorin fatigue. We demonstrated that objectively in a sci entific way in a laboratory, in this manner: . We tested individuals for the flicker phe nomenon rate which, as I said, constitutes ..Our base line. Afterwards, we stimulated -estate the quesI Iy wants to find low I.Q., so ta phenomenon of rumstances as an ..:;;*heir ear with a sound of a Tegular`interf-' -.aity, rhytlim and rate, the object being to whether we could fatigue one center of _ the brain and in that way effect fatigue in ,, bother center of the brain, or whether we could distract one center fromi tlie other. ight. say he does, *1* recocnized. We found that this investigation brought light two rather interesting things, or I *ould say three, perhaps. One is that there are- constitutionally, individuals who are sensitive to sound, because we could pick out from a group of individuals people whose flicker phenomenon was greatly de pressed when their cars 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 other 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 the radio is going on and understand both of them perfectly satisfactorily. 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 found that fatigue ac centuated the direction of their natural con stitutional tendency. In other words, the in dividual to whom stimulation of the ear depressed the flicker phenomenon found that depression increased at the 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 vounccr individuals. In other words, it is ip I '\pt 1 i. [!! w * .T.5& i! :$ii im n ;;; vwr*'V1 SSK ;&'vis. V-T'.V JWtS r8 feikh. V'jy^'.*.y$ 3&.- ^i RC-AtM M mmtmmft-V.IJani 2Sa*Li? S"'^f--_.,A* $& ^L. ^^ ass*>.r-,%v -; a I:.- i'& $r''.' - i\ i'H '-' .<, ! ] ;.. i m i.*n P?.:vT. 172 2P//r .Vaf/unu/ Safely 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 tor 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 lias 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 ail 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 by other substances such as benzol in 5 to 10 per cent in certain gasolines, cer tainly would alter that sate threshold. vfhe next group of solvents which arc slightly more toxic, arc the amyl and butyl acetates anti ether which are allowable in -100 parts per million. Some authorities stilt state that they belong in the 1,000-part-per- million class.'The most recent report classes them as 400. ( The third group of 200 parts per million y include the following; Methanol or wood :- alcohol which, as you know, may have a serious effect on vision and cause blindness-^! toluol and xylol, tetrachJorethylene, tfv.^j chlorethylene and turpentine. ^ anyone in the factory. We profession have always felt put our cards on the table. \ is a great deal simpler to to axiom and tell the truth. S< for instance, the benzol com; oa its barrels, the word "Pc in a position to know whctln The fourth group, which has dropped to^.' 100 parts per million, include carbon tetra*$ chloride and_ethylene dichloride. 'rSf? Then the fifth group of 75 parts per mil lion, benzene and dichJorbenzene; and finally f nitrobenzene, which we, fortunately, acta-w ally use very rarely as a solvent, is 5 parts ir per million. less did that because they w I know they do it. I think there are many c that should put the same labe ucts. In this connection I w< of a case that I was asked young boy, in the middle c working in a shop which ma I think it is important to remember that?! denly became very sick, had s these solvents, if in sufficient concentration^ Has di2zy, and had to stop may kill. This is in contradiction to tbt?- working with a substance wh other subject that I have been given, whiefr^ is harmless. is lead, which very rarely kills. These When I first heard of the vents kill, first of all, by simple sunoeatioo,jeT I would want to see the proc if they are used in an enclosed space,'swag||r; plant and get my inform: as in a vat. But the sinister element of solvent, of the toxic solvent, is the fact rather than attempt to talk t< //; by telephone. (The medical it affects the central nervous system becauS& hole is learning that'it can as you know, these solvents are fat responsibility by demanding and our nervous system is largely made now all about the exposure of fatty tissue or lKipno/iiMd ttilscscuiies, Cso/i tthhe* nerv'^J "tthinattcome int. o t.he.ir ha*nds.) ous system is very easily affected. We hayet involvement, therefore, of the eye. one the most highly developed nervous stnic| tures. Then we have central nervous systes^l involvement, paralysis, inability to ivafch* When I went into the she tilnus iworker was using a lar dipppiing it into a large bowl < be then slapped on the mi Also, we must realize that some of thgfry^ grease off. On this particui solvents actually damage the liver and kidney, causing an acute Bright's disease.JG|I evolved the idea of setting otdinarily, perhaps, blew th >. front him, directly opposite is thought that some of them may catwg: cirrhosis of the liver. Bateria) and blew the tumes " fact. HeNgot cooled, and th< Fortunately, one of the best solvents one of the most dangerous is not iflcluft^. ' I asked the foreman wh: in the list at all now, the tctraci:lorethyf**^j , piaterial, and he said he didn't group used in the airplane industry m "ski / 4 was stock material, perfec past. That had the peculiar ability to a* ** he knew. I said, "Well, 1 know what it is." So there v. every part in the body, including the upvit; ........ .. muscle. That, too, is said to be a c0TnttW& i*o a.n? , routine. We fi- inant'of some of our other solvents- I* ' V finaP ^ 'n l^e yard, co been mentioned that possibly contammancc in tncnlorcthylcne was .* benzol marked Jthe reason why trichlorcthylene had i,,,,lly M . rattier M name. nQ nn. .L. . fi%*** The'" P I think one of the most imprt3nt - C- the same t to remember in dealing with the e A f the f- ' *lad not gotten tl: a good solvent is that we are dealing' ' potentially dangerous substance & zgEX-i curious tw,*. make any effort to conceal that t*e gjjffiy1' '?cP..*,*s that ^ ftbout 5 (7;v:r^sr':-Vv n ano( her <! Occupational Piscasc 173 ' report classy ns per million, ianoi or wood may have a ause blindness; >rcthyicne, tri lls dropped to c carbon tetradc. 5 parts per milcne; and finally rtunatcly, actuivent. is 5 parts remember that t concentration, adiction to the cn given, which <ill$. These sol* iple suffocation, >$ed space, such element of the is the fact that $ system because, are fat solvents, largely made up sue, so the nervffcctcd. We have the eye, one o: nervous strutnervous system .bility to walk. some of these :e liver and the ignt's disease, h hem may cause >cst solvents arJ - is not include^ jtrachlorethylf^ industry' in d* ability to attack ludine the to be a contact' solvents. It has ibly the fonr ylcne was ra.' '.ylene had one important tiling :h the control rc dealing - stance and ^ 1 that fact >r"' vonc in the factory. We of the medical tofession have always felt that we like to our cards on the table. We know that it ^.?j a great deal simpler to follow the ancient * ' axiom and tell the truth. So that I admire, {or instance, the benzol company which puts - its barrels, the word "Poison." I am not jn a position to know whether they more o' V less did that because they were told to, but 1 know they do it. think there are many other companies ?V*lb2t should put the same label on their prod ucts. In ^is connection I would like to tell r%f a case that I was asked to see, where a 1 "young boy, in the middle of the summer, fworking in a shop which made motors, sudr.doijy became very sick, had severe headache, -?was dizzy, and had to -stop work. He was .JkSrorking with a substance which he regarded harmless. .l^NVhen I first heard of the case I insisted V*1 would want to see the process and see the aslant and get my information firsthand ^father than attempt to talk to some foreman h-j'iy telephone. (The medical profession as a 'j/whble is learning that it can only fulfill its ^'responsibility by demanding the right to ;l;fciow all about the exposure of the patients .,;that come into their hands.) y 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 pease off. On this particular hot day he croived the idea of setting a fan, which ordinarily, perhaps, blew the fumes away from him, directly opposite the bowl of oaterial and blew the fumes directly jn his Jice. He got cooled, and then he got sick. r I asked the foreman what was in that ..oaterial, and he said he didn't know exactly; ai was stock material, perfectly safe, as far I said, "Well, I would like to w what it is." So there was considerable 'Upsetting of routine. We finally went out oto a shed in the yard, completely dark; ?e finally got a flashlight, and we found a . rre! of benzol marked "Poison." ^0w> no one in that shop knew what they . V** doing. There were a dozen other work, each doing the same thing but who, rtunatelv, had not gotten this brilliant idea of the fan. 4 nc curious thing about this particular 'P "'as that in another department, not 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. 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 him he was going to die, and another one said there was nothing the matter with - him. Again I demanded to sec the shop. Wc 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 the one man in the shop who was delegated to clean the spray guns at the end of the working day. He would sit down and squirt material, which he called chloride, in and out of the 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 the end of even' day. However, finally he noticed he was getting weak, he was dragging one leg, and his heart was going very fast. Well, this illustrates 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 wc found that this was a material which they had bought from a supply house in another city, and they did rot know what was in it. We finally found out it was ethylene dichloride. The course of that individual is interest ing, in that we put him in the hospital. It eventually cost th3t company quite a lot of money. I was in this to find out all I could learn" about '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. Well, he came through, and interestingly v c found that lie had an opportunity to dc- 174 29th National Safety Congress velop a cold once or twice. Every time iie did, he developed jaundice. Then, of course, we did liver function tests ar.d found reduc tion of that. We found he had a weakening of the heart muscle. We found a definite loss of the reflex in one ankle-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, I 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." Unfortunately, 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 'aid, "I have lead poisoning," do r.ot forget he may have some other disabilities and diseases, such as acute appcndici::*. gallbladder, kid ney colic and so forth. In my private prac tice my" intefesrhas bee":'Sharpened so that I always make an effort tt take a very care ful occupational history -,n a patient, even though he may come to rr.e purely as a heart case, lung case or what-hivc-you. In this particular plant 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 ten ytar$ course, as r ago we were having an incidence of abotr 2-i lead cases per 100 employees per year first smooth ^ cooled, which corresponds pretty well with the per! grinder ant. centagc of 15 to 16 reported by the Public Health Service in work about that time. In five years, by cooperation with the medical department, the engineering depart ment and management, we dropped that to an incidence of 2 per 100, and tor the past five years we have had no cases of lead poisoning at all. We are still handling lead, and we arc still handling it in large amounts. I think that in the storage battery indus try. probably, men are exposed potentially, at least, to the greatest concentration of lead for absorption directly into their bodies than in any other industry. I am glad to report that, having followed this particular group of workers of about SO for this period, at. the end of ten years they are certainly just as healthy and, in many respects. I think healthier than the general run of the popu* I lation. Of course, we have reduced their lead absorption, but at times it will breaks, down the physical resistance and respiratory^ protection. They occasionally have larger doses of lead. Many of these workers were-' persons who had had lead poisoning or seriy. ous lead absorption in the period of servation. ' "? Lead is one of the most widely used so* _ called poisons in wcil 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. Xo expense is spared to study the men and to reduce the continuance of any exposure. However, in the small industry,., which is the major portion of industry lfl.\ this country, lead is cominuaiiy cropping "? and even silicosis, which got the center o finely divide the tact the any lead int gentember more dange very rarely through the cepuon of organic and It is rat; smaller pla give up ma Here is a r borse-and-b to hand fi.Hr are heavy The proble: by machine It has ah tug was veperience in it is very* ra where lead substances, forth, whicl however, le. because it stand the w Here we fcely efivk bum off o! the large i either by rr ing. There divided du remember ; rectly into culates thre the stage in recent years, certainly in * J>` I make c cousin, has now taken a back step, and W worker has come back into its own. together "1>_- lnf off/ior the ever increasing use of solvents. '. I would like to stress again the here is one of non-recognition, that we our trouble in the small plant, not in large plant. I will rapidly run trough ^ purpo Worker. In the v. shiPS, of c mce of le: types of industry where I have seen poisoning occur and in which it >s `,n portant factor. Tire most important is the -torage ^ industry. Then the streamlining of onr ^ mobiles and trucks where, after wckii1=' coatt wtms a f< Invis J? system **"8 that opinion is Occupational Disease 175 course, as many of you know, they were at 'f* abotj; -r year. ilc t*,. ' Public lime. *rst smoothed off by lead paste which, after t cooled, was then ground by machine Linder and produced a great amount of fLjjv divided, inhalable dust. This brings up T5 {act that the most important hazard in Iead industry is the point of inhalation. 'Uh vr,c- Remember that lead dust inhaled is much dcpan. that to lUe of leajj "g lead, unounti. jjjore dangerous than swallowed, and that ' very rarely are lead compounds absorbed 'through the skin, perhaps with the one ex oeption of tetrachloride fluid which is an "/organic and fat soluble substance. It is rather amusing that many plants, y Indus- [./smaller plants, particularly, have had to -entiajjy. -Lve up machine grinding of welded joints. 5 of lead L-Here is a return of modem industry to the lies than ijjborse-and-buggy stage. They are going back 0 report t group eriod, at inly just f think le popued their :li break .piratory e large ers.-wae' ; or sen* 1 of ob- Vjto hand filing where, of course, the particles kpare heavy and are too large to be inhaled. /.The problem can be licked, however, even jSjjy machine grinding, if one uses respirators. >3`It has always been said that lead poisonfesing was very common in painting. My exIs&perience in ordinary painting nowadays is Jg^itis very rare, particularly on inside painting jbere lead has been substituted by other itances, such as titanium, zinc and so forth, which are harmless. On the outside, :ever, lead is still used, in many instances, ^because it is the one substance that will used so* ndustries. the large led. First -ry effort tudy the , of any industry'. lustry ^ping u?; enter d id the weather. ere we come again to the question of . y divided, inhalable dust where men re*Jmni off old paint in private homes; not in ;5*.'tbe large installations, of course, or sand, 'iittther by machine sanding or by hand sandp'There wc have the question of finely J:':".. divided dust which is inhaled. You must i .remember that dust when inhaled passes di[V,rect3y into the system and immediately cir;COlates throughout the entire body. in \\i* ~ I Make a recommendation, therefore, that and lead soy worker that has gotten his lead by burn- iicr off or sanding, be given a respirator for j-:-.laat purpose, even though he is an outside : dangef K worker. we hs't >t in the ough th< -cen It3'- i an '"t/J0 the wrecking of old buildings and old - *** f course, there is the constant pres; f had absorption when the steel has '-forr! coate<* "*ith several coats. It ideally ' jT5.1 fume which is so fine as to be al- 0 baiter? *ir at0: kling. '. invisible and is absorbed directly into '^inS^S|!em' ^1C only "-ay that a worker ? P.oipont.hast can to really use an protect himself, in my air-i.:ne respirator. I have seen a great many men in one particu lar type of 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 Wis 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 rcmclts 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, wc have had only three cases, one of which was really a serious case, and that man was one who rcmcltcd--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 portai 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.o,'negrS--reduce- the-exposure to 1.3 milli grams, I don't think you will have a case oi 176 29th Xatioual Safety Cunaress lead poisoning. However, as a matter of practical intcre.'t. I think it is very difficult to yet there in ordinary industry, and I would more or less formulate 3 as a sate level. I think it na< also been found by other workers. However, if you get over 3 you certainly have the possibility of serious lead absorption. I 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, but that does not make lead poisoning. That is merely evidence of absorption. He must have, in addition, clinical symptoms of one of the three types of lead absorption. As a final word in regard to the role of the medical profession in its cooperation in industry, it seems to me that the medical matt should first of ail 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 be 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 informed 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* PAINE: 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-fj ora 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 of the lead doc> not exceed 500 degrees? DR. BELKNAP: That is a good prac, tical question. As wc know, lead melts at a much lower temperature when volatilize In my experience, lead does not really voiai tilize until around 1,000 or 1,100 degrees. In this group of workers that I am fob lowing, some years ago, large lead pots, two or three feet in diameter, were unhooded be. cause of certain changes in technical pro. ' cedure, ami the plant never got around to the hood. I disapproved of that and re- ' peatediy 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 )>ecn practicable, and I am here to say we have had no lead cases develop to the point of disability, and we ( have had 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 from 850 to 950 degrees. In this group of^ linotype workers wc found no evidence ohf lead absorption in some of the shops w they had no suction. I would not say in m; own experience that hooding is necessary at 500 degrees. 'A MR. CARR: 1 wonder if there is any evidence to indicate the toxic limit for butyl alcohol could be raised above that given?^ We bad experience over some twenty years';? with the same group of men. working ifl't; concentrations from 200 to -100 part: million, and under careful examination they-i; have shown no indication of trouble. One other question is whether much woric<lias been done on toxic limits of dioxene? ^ DR. BELKNAP: I think Dr. Hamilton^ wiH have to state if she recalls whether we,;., have toxic limits established for dioxene. DR. HAMILTON: Dioxene is the trade j- name for diethylcnc chloride. No toxic liif'j has been established for that We considers it a fairly safe solvent until some very dis astrous cases occurred in England . ovcr-cxr*c-ure, causing five deaths, bio- then we have looked upon it with a 8" deal more suspicion. There has not . enough work done on it to establish maximum allowable concentrations. >| DR. BELKNAP: In regard to bitty1*]., cohol, the butyl radical acetate is much toxic than ethyl or methyl, particular I would be interested in vour point of { think probably it limits- MR. GL.MMAR: pkcely the principle of safety standards should be based on toluene, there have in the lacqc-. painting came into t air as fine mist, a: orates at a slower inhale the mist, vot is toxic. I have employers State, New Jersey, who for the past si any reported cases c inj; yet Ohio in thad over 69 cases line in the petroleur As to tlie experi: no experimental da should be such a confusion arises i tinguish between c. ,'aig. Jt is a fact tb. ` centrations, toluen .toxic than benzol; chamber where th million, you would from toluene and with benzene, but t . Phenomenon from mg. CHAIRMAN I be "Skin Aff handled by Dr. M. DR. if. ,0 what e ^Posed tc plants ar "ot surf are ; Uited St; "^tes 69 | ?r< sJn d, * 100.000 year, i affec: of t h"s- Skin Occupational Disease 177 temperature 0f ; degrees? I think probably it could he made at safe gouts. s a good prac. lead melts at a 'hen volatilize^ not really voU. 1,100 degrees. MR. GUMMAR: I want to endorse com pletely the principle of maximum clearances of safety standards in engineering, but they should be based on factual data. As regards toluene, there have been enormous quantities that I am f0I- B<fd in the lacquer industry since spray -c lead pots, two panting came into use. It is sprayed into the -re unhooded be. air as fine mist, and even though it evap a technical pf0. orates at a slower rate than benzol, if you r got around to inhale the mist, you get severe effects, if it >f that and re- atoxic. we cases of lead in't hood. They l as it was prac-acticable, and I ad no lead cases ^ability, and we absorption result ave worked there I have employers in four states, New York State, New Jersey, Ohio and Connecticut, icho for the past sixteen years have not had ay reported cases of chronic toluene poisonling; yet Ohio in the past sixteen years has had over 69 cases of poisoning from gasoN]jnein the petroleum industry. i out of the pot, 7" As to the experimental results, I can find is ranging usually 'no experimental data indicating the toxicity In ibis group of should be such a low value. Some of the d no evidence of -confusion arises from the failure to dis t the shops where tinguish between chronic and acute poison- uld not say in my fllg. It is a fact that in extremely high con ng is necessary at centrations. toluene and xylene arc more toxic than benzol; that is. if you go into a if there is any chamber where there arc 20,000 parts per ic limit for butyl million, you would be unconscious quicker nove that given? ' from toluene and xylene than von would nnc twenty years i with benzene, but that is an entirely separate iiH'ii. working is phenomenon from tlie slow chronic poison- o 400 parts per ; rig. examination they ' CHAIRMAN PAINE: The next topic or trouble. I will be ``Skin Affections'' and that will he ether much work 1 handled by Pr. M. I. Router. :its of dioxene? ' nk Dr. Hamilton Skin Affections ."calls n-hctljcr we -<i for dioxene. xcuc is the trade dc. No toxic limit at. We considered :il some very d:?* England ircm vc deaths. S:"ce n it with a good re has not beer ' to establish ; ".[rations. j DR. M. J. REUTER: When wc consider to what extent the skin of the worker exposed to injuries, the action of chemical irritants and the various infectious agents, i: 15 not surprising that occupational skin dis uses are a major problem in industry. The United States Public Health Service c-t:^ates 69 per cent o: occupational diseasefr$ skin cih-e.-fSTs. They carried out a study 'n 100,000 workers and found, in the cours;of a year, that one per cent of these worker? "ere affected with some skin disease as ?. card to hmyl ?'' ' result of their work. This did not include '.ate is much ^urn$. splashes of acids and alkalis, and the 1. particularly. :*r point of Oman- r::< infections of scratches 'l)rasionv The problem confronting the physician is to determine the relationship between the skin 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 uncleanli ness 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 the normal protective coats of the skin, that is the outer horny 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 are much more prone to occupational dermatitis of the hands. Apparently this infection of fixe feet act? as a sensitizing factor. The actual causes of occupational derma toses are mechanical, physical and biologic agents and chemical irritants. Mechanical agents produce bruises ami lacerations, as as friction and pressure resulting in various inflammations and thickening* of the skin. The physical agents which may produce an occupational dermatosis arc heat ami cold, 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. For the most part, however, occupational a sections of the skin are the result c,' con tact with irritants of a `homicnl ".attire. * it I'-liJ r-! fi-: m 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 workers are one of the most potent factors in the causation of occupational dermatitis. CHAIRMAN PAINE: This is a subject in which there are a number of men inter ested. Will you expedite your questions? DR. ENZER: I would like to ask Dr. Reuter to say a work about skin cancer in occupational exposures. Skin Cancer DR. REUTER: 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 and adequacy of injury must be estab lished.'' That is, the patient's statement re garding injury must be substantiated, and there must be actual tissue damage. "Second, the previous integrity of the wounded part before the injury must be established. "Third, the cancer or tumor must arise at the point of injury. "Fourth, there must be a reasonable time limit between injury and the development of the tumor." That is, if the tumor develops within two or three days after the injury, it isn't reasonable that in that short a time a tumor could have developed. "Fifth, the positive diagnosis must estab lish that there is an actual tumor present and the nature of the particular tumor." CHAIRMAN PAINE: Dr. Enzer, do you want to speak to the point? DR. ENZER: 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 aninjal; 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 'skin.' 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. L`R. REUTER: I have had very |jtli j occasion to pass on a question of cancer * the skin arising from alleged contact wja some carcinogenic agent. C. T. DENSMORE (Koppers Co. $, Paul. Minn.): I would like to hear a`littU about the effects of coal tar and creosot : oiis in relation to cancer and what-nor and also the inhalation of the creosote \\ Prs . ajgfc DR. REUTER: Regarding the develop ment of cancer from coal tar and creo$ou>' I have had no experience. Wc do know th^ coal tar is the nearest to the skin and doa' produce an inflammation about the hijr? follicles called folliculitis. It is undoubted}?? cue to the plugging of the follicles with the tar and perhaps some stimulation of epidermal layers of the skin from the tar ; which sets up this inflammatory readcaaround the hair follicles. I think the saraeip true with creosote. But, regarding the actual' development of hypertrophic lesions of skin, particularly cancer, I have had no perience. DR. BELKNAP: As for creosote, liuS had no actual cases brought to my Vtfe tion. As far as I know, the fumes would no more irritating, possibly, than causing*"* irritative cough. I know of no cases, c: acute chronic bronchitis or other35? cinogenic results. './cl CHAIRMAN PAINE: We will lswb any other questions to the end of the so rion and hear Mr. H. A. Nelson, IndasIWv. Commission of Wisconsin, on the questioak 'Should occupational diseases be consider^-- ?.s industrial injuries?" Disease Vs. Injury |||. H. A. NELSON: Mr. Chairman: Tt*-. question which I have been assigned is ceptible of treatment in several ways. ^ { :an treat it in a highly technical way quibble about the court construction ot - word "injury" or we can treat it in * 5 `rai way and ask whether occupations ^ -ises should be compensated. That > r-ral crux of the question today. ' It somet.imes astonish. es me ,Cil,9. thirty yiars after the passage of compensati ^ we are still disputing this <llies whether we shall compensate a 5? afits which may cause disability and w'hic ^ ,t of industry just as clear' ^dental injury. There 3re va feting the problem. One. o: Soothing about it and that i Jcbteen states in the Lnion ar. II not compensating occupar. \ ail. Out of the other state L, which are compensating ecual diseases, and some of ti peosating by schedule. Sow, schedules are usually tel there are a great many c are named, but very generally that they leave out the one occ ose which causes the most d example, silicosis is left out of of the state Jaws which.ha' Therefore, silicosis, which is ccpational disease is not compt When we go back to the pri of workmen's compensation, w< the compensation fathers did question at the time the comr were passed. That was the ti Either through inadvertence eases; through design, occupat. were left out of the laws pre bqt'accidental injuries were tc sted. I think that was largcl the rather violent split from the few system and leaving out of the question of negligence. It 'riolent split, but it is surprisir these years occupational dis1 "`am uncompensated in so mar. When we consider the natur Wwnal disease, which is u$nadious process, over which the employee, has no con the employer, as the: "**e told you this morning, i j^cr of control, there sccrr undred times more reason \ who cannot protect hi' . e way should be compcn ^Wional disease rather than injury. I suppose there is no ques; crux of the matter is cmPlyer* and th . `he so statcd-accrutfd 1 erj-rt, n an accrual of dosage > disease, and th "**aent. the disease may con H the employer has a larg ;i|?i ;H ' I m 29th Sationai Safety Cono>ws ease be compensated. The trend is coming: on. I believe that industry and society will be gratified when the problem has been solved by whatever methods may he adopted and suited to the different states. CHAIRMAN' PAINE: Are there any questions you want to ask Mr. Nelson be fore wc 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 wc passed a most illogical law, the all-inclusive act which acted most disastrously not only to in dustry itself but to the workmen. You are 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 wc arc showing generally throughout all of the states that the problem can he solved. Protection for Welders CHAIRMAN PAINE: 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. I. S. GREEN (Edgcwatcr Steel Co.. Oakmont. Pa.): I would like to ask to what extent an ordinary welder in a small plant should be protected? Otv:e in a while there will he a hardening materia! 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 PAINE: The question is, how arc we going to protect, and what is the exposure to welders on new material or on old material that has been painted? I will a^k Dr. Walsh to answer that ques*iion. DR. WALSH: Within the past couple of years wc have had occasion to go over a group of about 1,000 welders. Of that group some 300 have been welding for ten or more years. They were gone over from tiic clinical point of view. X-rays of the chest were taken. Disability due to sickness over ft ten-year period was calculated and seen fo' each individual man. There certainly was no marked difference in sickness rates and in disability rates in the welders as compared to the general run of employees working ^ ^ who might Very rate iron ^virtual who ha ; ptff cent const:: ' for the iudividVast there. their side in the same plant and in the same \'ow, when wc economic situation. V 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 for the ordinary welding group, working in a large, airy room, with ordinary precautions and ventilation, their health is just as good as any other group of workers. If they are cutting paint or toxic coatings of any kind or lead-bearing steel, or if they are jfe limits of an : 0 that the pro. alved by a bla rtblem. but by jsalysis and stuc :^ed to the indv `ay that this ca: jistry realize tha ie forms the k iese problems. working in a confined space, then additional DR. BELKNA respirator.- protection is necessary. jEfy what has al So far as the question that was rampant a few years ago, that is the development of so-called fibrosis of the lungs due to we!d-; ing, we have not found this to be the case.Dr. Enzer and Dr. Saucier at Milwaukee have had occasion to examine at postmortem'1 iat is when a \ aaterial that ha nth lead, he, oi quire lead absor ibout as quickly aoy other way. a few of these individuals who have been-'- It is very rim welding for long periods of time in confined..* tors we have av spaces, usually. They did find there was an~5 .whenever he is < increase of iron in the lung but no fibroshx use such a respi: causing harm. "faS series of cases c Recently, wc also have examined another:' sorption was a group of wcMers. that is a variant of the . pairing some welding trace, scarfcrs, in the continuous amount of lead. production c: steel. These scarfcrs use a long torch a::d blow out the defects in the billets rather than chiseling them out. This, group also, while it is an infant in the group of welders, apparently have no health haz ards of any consequence in their trade. In other words. I think if ordinary precau- tions, so far as ventilation and so forth are concerned, we need not be concerned other than if wc are using lead or chromium or Also, I had c a dozen cases c op tanks in a steel tanks had could not ur.di letting lead. T with a torch 3' absorbed lead < a difficult quest mauer of havir some of the toxic materials. the work is for CHAIRMAN PAINE: Dr. Enzer will speak for a minute on the subject and then Dr. Belknap will follow him right up. MR. CARR: Vl' have had i work on galva DR. ENZER: I want to seize the opP tunity to make some comments relative n`trous fume coated electrcd' the general attitude of this panel discussionIt is most important that in any appro3 to the problem of industrial health wc r member tha: a statistical analysis of 2rllj^ is not a true criterion of the health of individual. In other words, just like the su ` would ai-< relatively new dcanrui ng of u'e of a spec cellule; ; prev: tmz Occupational Disease 1S1 sickness over the lated and seen {or -e certainly was no 'mess rates and io iders as compared ployees working at :it and in the same cftccoonvewrvhoramteigfhrot mboaasst poecf ifiac 99^2 per cent operation, the individual who happened to belong to that ,, per Ccnt constitutes 100 per cent mortal- for the individual. There is a very sharp ;,Jcntrast there- j^osVi when we talk about safe limits of toxic solvents, safe limits of toxic agents, ring welders who trials, lead-bearing Iding in confined rent problem; bat group, working in : ordinary precaa* !r health is just as of workers. If they ic coatings of any 1, or if they are limits of an industry-, we must remem ber that the problem is not going to be "solved by a blanket generalization of 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 iniustry realize that the profession of medi* - cine forms the keystone to the solution of these problems. ice, then additional necessary, DR. BELKNAP: I simply wanted to am> plify what has already been mentioned, and that was rampant the development of lungs due to wddthis to be the cast .rider at Milwaukee .mine at postmortem that is when a welder or cutter works on '"material that has been painted or coated ^with lead, he, of course, probably will ac quire lead absorption in a serious fashion Aabout as quickly as, if not quicker than, in `^anyother way. rals who have bees - of time in confined d find there was az `mg hut no fibrosis 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 examined another sorption was a welder who had been rc a variant of the v pairing some ovens containing a large in the continuous 1 amount of lead. sc scarfcrs use * j the detects in the | ng tiicm out. Th'.f I infant in the grout ! ave no health haa- in their trade- i- j ordinary precaa- j n and so forth art I i>c concerned other id or chromium cr is. Also, I had occasion recently to see half a dozen cases of cutters who were cutting op tanks in a large chemical plant. These stee! tanks had been lined with lead. They could not understand why the men were Retting lead. They went through the lead with a torch 3000 or 4000 degrees and they absorbed lead exceedingly rapidly. It is not a difficult question to solve at all but it is a patter of having perfect confidence in what >he work is tor and preparing tor it. ' : Dr. Enzer wa:c subject and t-:iim richt up. to s,ji2e .thc-OUP0^ imiwntf relative .is panei di.-cussiC'-; ,t in ar.v appro5rrial h.eaith we ^ analysis of gr0`-; ; th.c i':.a!th ot 1 ju<t like the s- ' CARR: In connection with welding. *e have had instances of zinc chills from "ork on galvanized iron. VVc have also had -P.ik&u*-- ft?ymT"jfoisoning from the use c: coated electrodes. j would also like to cail attention to a r^atively new development, that of the flame ^carting of metals before painting, by the ;;e 0f a special oxy-acetyicne torch. That u'ies previously tainted metals as w Y. 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 unpinger 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 6S0 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. REUTER: 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 mot people's skin. It is a question of whether in itself it is not an irritant to all people's skin. Wc used to think we knew the cause of l>oison ivy dermatitis, but more recent work has tended rather to disprove that wc do know the actual cause of what it is in tinplant that produces dermatitis. Apparently it is a water-soiublc fraction rather titan 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, WPA worker, lumber man or any occupation that keeps an indi vidual out-of-doors, and he contacts poison ivy. it certainly would be an occupational disease. Poison ivy dermatitis is apt to he a much more violent dermatitis than ilia: from hemlock. CHAIRMAN* PAINE: Mr. Cnimavr, will you repeat your question? P. \V. GUMAER: The question was. what is the basis of the comparatively low maxi mum concentration of toluol in the al><.nce of any .reported occupational disea-e and arc there ar.v experimental data to war rant such a lew concentration where -ik-:: experimental cats deals with chronic poi-or.- and not with acute poi^oninir? i\< # 't,ii i lma rm\ )!S m 1*2 29th Satioual Sofeix Congress DR. BELKNAP: The question is, Tiie American Standards Association has whether toluol is really as toxic as 1 inti a committee at work in this field, with a mated it might be, being permissible in only small subcommittee. We have just finished 200 parts per million. Is that right, Mr. dealing with two gases and two volatile sol Gumaer? vents, carbon monoxide and benzol and car MR. GUMAER: Yes. DR. BELKXAP: As far as the official authority of that is concerned, it is taken from the code for safe concentrations of certain toxic substances used in industries, whose authors are Bowditch, Drinker, Hag gard and Alice Hamilton which appeared it? the June 1940 issue of the Journal of In dustrial Hygiene and Toxicology. 1 do not know whether there is any prac tical experimental work backing that up, hut inasmuch as toluol and xylol are very' closely related to benzol, I assume that the authors felt that it as yet could not be given an entirely safe record, for instance, com pared to gasoline. I will say, among a group of workers who have been working with adequate protection for several years with toluol solvents, I have seen no general reaction. DR. HAMILTON: May I speak to that for just a moment? That presentation to which Dr, Belknap refers was got out simply because a small group of us felt that we might as well let the public know what was our best guess at the present mo ment with regard to maximum allowable concentrations of the most commonly used solvents. Jt is founded very largely on guess work. The quantity of 1,000 parts per million for gasoline is guess, and so is 200 parts of toluene. Wc are hoping that wc shall be able to give more accurate figures presently. bon disulphide and hydrogen sulphide. There we have been able to get pretty accurate figures because we have data to go on. We are now trying to deal with twelve others which are going to be increasingly important in the munitions industry. We hope to be able to give out more accurate figures then. But it is a very difficult prob lem. You see the only way we can get any accurate figure is by having a combined inquiry made by the physicians, the chem- ists and the ventilation engineers, because we have to know how many cases developed in a given workroom at a given concentra tion, and also at what concentration done, cases come. Wc could do that with the four I harementioned, but it means, as you see, a great deal of careful study in tiie factory and in... the physicians' examining room. Bringing' those two together, we can do it with r*v gard to lead; wc can do it pretty well with* regard to mercury, and wc have pretty good*7 data with regard to zinc oxide fumes galvanizing iron and brass foundries aoiy. zinc smelting; but the rest of the substances* still are more or less in the realm of guess~ work. >. CHAIRMAN PAINE: May I, in yourj behalf and in behalf of the National Safety- Council, thank the gentlemen on the plat form who have so kindly led us in this dis cussion? Will you express that thanks by giving them a rising vote ? . . . The audience arose and applauded.. V Inc ranei jjiscuss ridents was called to -an, Julien H. Harvc :ar. The National C New York City, who CHAIRMAN HAR' :o welcome you here t: of introduction, I simp] just what the National in mind by the phrase dents." All too freque sions of this kind tiier that we were thinking enmity" safety work, dunking of safety wc basis, but in another c linking of a progra; vidual industry or co the problem of accidcn - employees during the i away from work. Thi inception some seven following several sur diat a very great pr< dents occurred to emp' kit the job, as comp occurred while they I recall one illustrat: a "ell known nation man>' thousands of er Sod job of safety wc ^P'te that fact, durjn; f their employees V 'VOrk, but during tk ADJOURNMENT jr employees had b whistle blew." JVe found that situa: '^tances. Proceeding '"dustry is closer to it b.Sm?!tions can he, : T . ahk to do a goo< the wa dirl iT{fTa* mfgh tr?Sh a special pro fc* T"do son . f safety beyond to M?Ur ProSram thi up certain : 5S<) 29th Xatiiniti. Sittclv C`ni(/rcss this ventilating current be interrupted for a period of 24 hours and with the same amount of methane being liberated, there would be 5.760.000 cu. ft. of explosive mix ture. Should this be contained in an entry 10 ft. square, the length of the entry would he approximately 11 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 sj>ccificd percentage between .5 per cent and 3 per cent, it will operate special electrical circuits through suitable relays to cut ott the power in a section or give warnings in other parts of the mine {T to the outside. Methane recorders for co? timtously indicating and recording methai* in main returns particularly have been fectcd recently and are designed to be lo. catcd in fan houses or other convenient places. There is no relation between the volmj* oi methane given off in a coal mine aid the chemical composition of the coal, as botb bituminous and anthracite mines product methane, and methane has been found q metal and other mines when tunneling through carbonaceous shales. The comm occurrence and cxplosibility of methane art responsible for numerous mine disasters and every precaution should be taken to keep it within safe limits. This can best be done hy the use and guidance of methane detec tors. Pulmonary Diseases in the Mining Industry By DR. R. R. SAYERS Table 1.-- pupations cx Siliceous dus Sonsiliceous ikneral popuia iitis were fo*. so anthracite In the study iflnes and the JWier, Okla.,* asis or tuben. aong men wh iitis, pleurisy, 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 which 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 byirritating gases carry with them the risk o: bronchitis. According to Collis,1 it cannot he 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 ra'na Table 2.--Co: recurrent invalidity and incapacity. Mortal trts for Bron ity records compiled by Collis1 indicate* Groups i: that it is of a chronic traumatic origin asso ciated with irritating atmospheric coniC* _ *caJ miners*. . tions, rather than of an infectious origin.^ All undergro Statistics for bronchitis for the general Hewers and population and for workers exposed to dusts in Great Britain1 for 1921-23 show the rok played by dusts in the increased incidence of the disease in certain industries. The jhles in same '"occupied at of rate f erstoratefe comparative mortality per thousand (38** * 1# three I 26 to 65) for those in occupations expos to siliceous dust was 214, for those expose* to tionsiliceous dust 59.5, and for the g*" era! population 49.6. (See Table 1-) Tble 3.--Infii In this connection it is interesting to ^ among Bi the mortality statistics per thousand October 26 to 65) for coal miners of counties Wales (in which most of the coal nn ^ anthracite) compared with those foe ^ other groups in England and Wales, figures for coal miners are 112 derground workers and 139 for & getters compared with 46 for Tna eS.!ja^ same social class and 50 for all occup' retired males. (See Table 2.) pul# In a study by the United States Health Service* 35 eases of chron* V.r? Mininy Section 531 .. j__Mortality per 1,000 from Bronchitis in Dusty Occupations and in the T* General Population, by Age Groups Ages at Death Comparative Mortality Figure 'f>c volu^ m*n6 aaj :>a), as boii 2S Produce i found q tunntliaj :>e coanjeo 'ethane arc masters ar.i| ' to keep it st be done hane 4%. causes much :itv. Mona!* iiss indicate origin asj> leric condi* ous origin, tiie genera! sed to dusts .ow the role ;d incidencr stries. Tte isand (ages ns exr*i osc expose! or the sc!,` c 1.) ling to rc<f osand counties o' >al n'ir-ed * for r*5 .Vales* T* for all is; liewers a*::aics it & .ccup'ed ^ ::ites pub;-' -onic trrr- pupations exposed to >Sflfceous ^us:........... Vtfonsiliceous dust.... Genera! population------- 20-- 1.1 0.5 25-- 1.0 1.7 35-- 13.7 4.9 5.4 45-- 44.6 12.8 13.3 55-- 153.7 41.8 28.8 20--65 214.0 59.5 49.6 fe litis were found among 344 employees of anthracite mining companies examined, t-jjj the study conducted by the Bureau of yhes and the Public Health Service at fidier, Okla.,* the highest incidence of sili- or tuberculosis, or both, was found ignng men who reported having had brontfeitis, pleurisy, and asthma. Lrt' .Table' 2.--Comparative Mortality Fig^es for Bronchitis per 1,000 of Certain Groups in England and Wales Jwl miners1. 'vAU underground workers........ `^Hewers and getters.................. Miles in same social class.......... Ml occupied and retired males.. fatio of rate for hewers and get ters to rate for same social class Bronchitis 112 1.39 46 50 302 1 In three counties in Wales. to 7 -S' Tible 3.--Influenza-Pneumonia Mortal*7 among Bituminous Coai Miners-- October to December 1918 Annual Death Rate per 1,000 Ml Agest Bituminous Voai Miners 50.1 15-25 29.5 r---- 62.1 44.4 All Industrial White Males 22.3 17.5 32.6 11.7 ,',cn vear and Influenza and Pneumonia Figures of mortality available for 4,700 miners insured in the group department o; 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 SO per 1,000. Among all occupied males aged 15 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 65 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, for 31 per cent of the mortality in the group ot 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 Tabic 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 under consideration are largely rural areas may have made some difference. In the epidemic year 1920. the proportion of deaths from influenza and pneumonia was smaller than in 1918, but, as was`found tor the anthracite miners, the bituminougroup showod a wider difference in the pro- r 5: fill j; w'. Twi ..... m li* i SII K- ARni 111 ! ::l' I'l'y:-. --3T -d.- . .. */-. : v >32 29th Xaiiona! Safety Congress Table 4.--Percentage of Deaths from Influenza and Pneumonia (After Deduct1 Accidents) Among Bituminous Coal Miners Compared with Farmers, and W* l Other Males in the Same Areas of Several Soft-Coal Producing States' ibis 5.-- - Comparison | 16-70 Bituminous coal miners............. 31.1 Farmers........................................... ..: 18.7 All other males............................ ..1 18.6 16-30 49.4 3S.4 30.0 Ages 31-40 41-50 44.7 25.1 32.4 19.7 29.0 16.0 51-60 19.7 12.4 11.3 61-70 |Qj 108 10.8 iountiw <{ Wyo.umc. 1919-23. inclusive. The record for farmers and for "all oilier males" was obtained from the above-mentioned coal-mintnc counties, and'also from 3 ayricuhurn! counties of Wyoininc. 1919-23. pupations Siliceous c Xonsiliceo ikneral popi portion of deaths from this cause compared with "nl! oilier males" than in 1918. The percentages in 1920 were 29 for the softcoal miners and 10 for "all other males." fn this epidemic the bituminous miners at ages 40 to 60 suffered heavy excess mor tality from influenza-pneumonia, but the differential mortality was not quite so great as at age-' 10 to 30. Antone 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 whicli is certainly a significant variation.'' Thus, an abnormal mortality from influenza and pneumonia is consistently indicated among snincr< of 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 nonsiliccous dust compared with those for the general population were given by Coliis1 as 134.3. 76.0, and 85.3, re spectively; similar figures for influenza were 47.1. 49.6. a?;d 36.5, respectively. (See Table 5.) According to Brundage,4 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 but at other times as well. In a" studv bv the Public Health Service at Wilkes-Barre. Pa., in 1915-23 and 1906-254 it wa- found that influenza and pneumonia were responsible for 40 per cent of the total deaths compared with 25 per cent among males at ages 15 to 65 who had been en gaged in pursuits other than coal mining ia Wilkes-Barre and vicinity. The percentage of deaths from influenza and pneumonia for ihesc two groups by ages tor the years mentioned was 19.3 for anthracite miners compared with 13.3 tor males in other in dustries. (Sec Table 6.) Tuberculosis Jn 1925 Coliis* said that for coal miners generally the tuberculosis rate apparently is" low although miners at the coal face suffer from the disease more titan other coal min-ers underground and workers above ground;. Results of more recent investigations seem, to contradict the assumption that tubercu losis does not occur among coal miners. An' investigation by the Welsh School of Med icine, reported in 1937.* indicates that this supposed exemption of coal miners from tuberculosis may be due to a mis- or partial diagnosis. This investigation revealed a high incidence of tuberculosis (35 per cent if "probable" cases are included) among the pncumoconiotics of the South Wales cw fields and supports the theory that coal du. modifies the tuberculosis, leading to failure to recognize the disease or to the mistake diagnosis of "bronchitis." Studies by the United States Health Service10 revealed that 6 percen_ ^ hard-coal miners examined had c ^ pulmonary tuberculosis. The average p alcnce in the adult male population o ^ United States is about 2 per cent. The r* alcnce of pulmonary tuberculosis hard-coal mining employees at ages . 35 was slightly less than that found t studies among male adults 'n,, ,? j-o"'* population. In the age group 35 to ever, the prevalence of tubereulosi Occupations Siliceous <: Xonsiliceo General pop. about and fc lie ra ffS I kadi cr 3 thic. rod Table 6._T Miners a l>2 Mining Section 533 After De<iucti rmers, and Wjjv ng States' ble 5---Mortality per 1,000 from Pneumonia and Influenza in Dusty Occupations 4 and in the General Population Pneumonia 51-60 61-70 19.7 ioT 12.4 10.8 11.3 10.8 : of Indiana. i9jj. -producing counties .5 obtained from tv* 1919-23, Occupations exposed to Siliceous dusc............... .N'onsiiiceous dust------ General population------- ban coal mining o y. The percentage and pneumonia fcr yes for the yon anthracite minen males in other i&- Occupations exposed to Siliceous dust............ rXonsiiiceous dust... . General population. ... 1203.3 4.3 l.l 5.4 2.0 Ages at Death 35- 45- 14.4 30.6 47.2 9.6 13.7 28.7 11.5 19.6 '4.2 In tluenza 7.7 11.3 8.7 4.8 13.7 10.6 5.2 7.7 4.7 Comparative Mortality Figure 55- 20-65 38.7 134.3 23.9 76.0 25.7 85.3 18.3 47.1 14.9 49.6 12.0 36.5 about twice, at ages 45 to 54 about 5 times, and for ages altove 55 it was about 10 times ,at for coal minen tic rate found in the general population. i> rate apparently .The highest prevalence of clinical pulmonary the coal face suffet tuberculosis occurred among the rock work :han other coal min- ers (men who had been employed in rock >rkcrs above grotrnd .jading or rock extraction for more than 2 . investigations sean r;3 years). After 20 years' service, of :iption that tubenru- 1 /which more tiian 2 or 3 years were in rock oust coal miners. Ar. work, 37 per cent presented evidence of Mi School of Med- pulmonary tuberculosis. In a group of 335 indicates that this completely* disabled former anthracite work coal miners fro5 ers, which did not include any known cases lo a mis- or partis! of tuberculosis, 10 per cent proved positive :i<m revealed a h;:v for pulmonary tuberculosis. These findings (35 per cent it b* would appear to corroborate those of the iuded) among d- IVelsh National School of Medicine that in South Wales c; dicate that the supposed exemption from icorv that co3l tuberculosis of coal miners is erroneous due -. leading to failed 10 incorrect diagnosis. There is evidence or to the mists*55 ttat the above increased incidence of tu berculosis is associated with exposure to silica dust. The incidence of tuberculosis 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 deatli rate from pulmonary tuberculosis. The mortality rate for tuberculosis for Jas per County v. ns 200.8 per 100.000 tor 1911 and 1912 and 229.7 for 1913, according jo statistics of the State Board of Health." On the oilier hand, according to the Jasper County Antif.-.berculosis Society, during the calendar year 1912 there were 720 deaths among miner- who had worked 2 years or more undergreund in Jasper County. Sot ail ted States PW5;! .! that 6 per cent c'; nined had cl'.a.cs Table 6.--Percentage of Deaths from Influenza and Pneumonia among Anthracite Miners and among Males in Occupations Other Than Mining in Wilkes-Barre The average and Vicinity e population o: per cent. The Pre'_ tuberculosis tune- j vees at ages : that found d'.ro-^ 1 ____ >rouys l nder Comparison | 15-64 15-24 Ages 25-34 35-44 45-54 55-64 iults in die Mn\har^cke miners................... ...; 39.5 45.2 67/; 42.9 31.8 I'M ,,roup 35 to 4A h<! ( 4M in other industries. . . . ...) 25.5 28.7 46.2 31.0 16.8 13.4 t!ibn-eiil*'r *"* i 1. .] 'Mi fi M .Ji r!:!*Mj I t m -' : ; a* .Ji*. . . ; . W*;v\ '.U J9(h .Wttioiial Safety Congress Table 7.--Mortality per 1,000 from Pulmonary Tuberculosis in Dusty Occupations Table 8.--Preand in the General Population Ages at Death Occupations exposed to Siliceous dust............. . Nonsiiiceous dust___ < kmerai population........................... 20- 25.6 15.6 20.6 of these 720 deaths occurred in that county 'nut they had contracted the disease there and some of them had moved away, Of 93 tinners in the Joplin District examined by Lanza in 1914," 64 showed definite symp toms of pulmonary disease and 39 of the 64 iiad the classical symptoms of pulmonary tuberculosis. In a study by the Bureau of Mines and the Public Health Service1* in Butte, Mont., during 3916 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 from tuberculosis for the year, the rate per 100.000 was 1,207. The tuberculosis death rate of Michigan for the 10-year 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 clearly by figures for Great Britain for 1921-23.' The death rate per 1,000 for ages 20 to 65 was 592.2 for those exposed to siliceous dust, 172.4 for those exposed to nonsiiiceous dust, and 163.5 for the general population; for ages 35 to 44 the figures were 141.0, 46.1, ami 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- the figures were 150.6, 29.9, and 22.7, respectively. (Sec Table 7.) According to Collin1 the prevalence of bronchitis, pneumonia, and tuberculosis i* 25- 35- 1 45' 55- 20-65 63.4 141.0 ! 211.6 150.6 592.' 26.3 46.1 j 56.4 29.9 172.4 37.6 43.6 i 39.0 1 22.7 163.5 high among those exposed to silica dust but the incidence of these diseases is not always Outdoor and ind< indoor industries Coal trade.......... Alcohol trade. . . He3t and fumes. Dust of 1. Animal orig 2. Vegetable h materials. . 3. Silica......... the same under other conditions such as exposure to other dusts, heat and fumes, or working indoors. (See Table 8.) airnUrn of instar, wn probably w Anthracosilicosis physical condition rock workers, ant: From 1931 to 1937, 87 per cent of the table exposure t total deaths in Great Britain due to silicosis industries also si occurred among the coal miners of Sontlr jrtater physical it: Wales; two-thirds of the deaths and dis*V the control grot: case occurred in the Swansea Division; and; Moderate or mr. 89 per cent of the medical certificates;-; from any cause w: granted in the Swansea Division related to he control group anthracite collieries.1* !*Sukr miners, an In the L'nitcd States the chronic disease he rock workers. among miners due to breathing air contain There was a mr. ing dust generated in the various processes &^se :n the propc involved in the mining and preparation o* *irnttn:s with in anthracite is called anthracosilicosis. This t* Iters of employn a descriptive title for the form of pneumo 5cy is manit coniosis commonly called miners' asthma. Tiie disease was found in about 23 per cent of 2,711 employees of three anthracite mut disability o: T"icb pulmonary i: * disability due Ic ing companies studied by the United states Public Health Service in 1933. About ^ per cent of those hav:tig anthraoo>ihf^' ^ ^ the occt .^selves accordi: Jfeinr.tnt as folk showed evidence of disability, compared 'u less than 10 per cent in the control gj? Moderate and marked degrees of d|Sa ` y handicapped aproximatcly 21 per c*n ^ those with anthracosilicosis compared " ^ less than 2 per cent of the men sersmg . rt?a'ar miners I.0* than 100 r *>t of air; ; *s except rock w. pathology of f ea :a these case controls. ~~ t f coal dust in Wide differences were torn id i the **: several tent of physical impairmmecnti i"n t--he- occupational groups. The highest rate disability from all causes combm*- ^uTar':-ten.sive fil <F.;'-',thh assoc changcs' found in tiie group of men that had `-xccss nior more than 5 years before the daw animation from very dusty to reiati |n dusty occupations in the industry. ttu *> a whole : ard-cal min tf-adc by the Dusty 0ccilpju Mining Section 535 g__Prevalence of Bronchitis, Pneumonia and Tuberculosis Under Certain Conditions of Exposure Exposure Bronchitis Pneumonia Tuberculosis and indoor life............................................. fyfabr industries.......................................................... Coal trade..................................................................... Alcohol trade................................................................ Jot and fumes............................................................ low low high moderate high low low high high high low high low high low cd to silica dost bn [just of . aj; Ammal origin........................ .................. ............. .. |2;: Vegetable husks and debris, certain inorganic S&tmaterials. Jti' Silica. low high high low medium high low low high diseases is not alTyj.: ' conditions such a .s, heat and rtimes, Table 8.1 . .sjjhber of instances the change in occupaCjjj probably was made on account of The anthracite miners' proportionate mortal ity from all respiratory diseases was about silicosis -MM] tv- :`cal condition. Miners at the coal face, 1 Yz times that of the other adult males in gcck ww(orkers, and men who had bad appre- the same region. When proportionate mor 87 per cent '<>{*&? Sfofo exposure to harmful dusts in other Jritain due to salicms'v"t 3sjl.u,*s*t*r*ies also showed evidence of much coal miners of-SoatiJ-, greater physical impairment than was found ' the deaths and dis-? sfflie control group. tality was computed for ages 16 to 65 in Wales/ it was found that respiratory dis eases accounted for 53 per cent of the deaths of anthracite miners compared with Swansea Division; and - Moderate or marked physical impairment 38,2 per cent among males in the same social fmedical certificate i ca Division related to om any cause was found in 1.7 per cent of class. The proportion among hewers and Ikt control group, in 9.9 per cent of the getters of anthracite therefore was 1.4 times gtguiar miners, and among 12.6 per cent of that of men of the same social status. s the chronic diseax breathing air contain- --the rock workers. There was a marked tendency toward in Silicosis the various processes c and preparation o'i iracosiiicc'is. This ts :ne form c: pneumoHod miners' asthma in about 23 per ctrt throe anthracite tr.in hy the United State- in 10.:5. About 61 Am: artitrr.cosilico^' bilitv. compared w'1'1 crease in the proportion having physical im pairments with increase in the number of )*ars of employment in anthracite. This tendency is manifested whether one con siders disability of any kind, disability in which pulmonary infection was contributory, or disability due largely to tuberculosis. In ca^e the occupational groups arrayed r'omselves according to extent of physical otpainr.ent as follows: (1) Rock workers; w) regular miners: (3) all others exposed There are various definitions of silicosis hut ali agree that the cause of the disease is the inhalation of silica or quart' dust.14 Silicosis is a well-rccognizcd clinical and pathological entity at least as characteristic as that of any cause of death known to epidemiologists.1* The definition of silicosis, adopted at the International Silicosis Con ference in 1930 and reaffirmed at the 1939 Conference and generally accepted is: m the r.t'ol grotf more than lOO million dust particles per "Silicosis is a pathological condition of degrees ot disability ^bic foot 0{ ajr; an(j (4) nicn j_ }iaujage- tiie lungs due to inhalation of silicon diox .rely 2\ per cent ' nj's except rock workers. ide. It can he produced experimentally in 'oosis compared ,;- The pathology of anthracosilicosis as ob- animals." ' the m-.m n-rvine * re found rt die ': rnn-nt ::t cover1 Tiie Incite raw * uises e.-mt-med that red cha^ - rved in these cases is essentially a deposiof coal dust in the Jungs, accompanied A*0 extensive fibrosis, both diffuse and - Uar- "'!th associated functional and de nature changes, (silicosis modified bv Oaldust,. ^;'Teai 'at ex'CcS5 mortality from -e-piratory The first investigation ot silicosis in the mining industry in the United States was made in 1914-15 by,.the Federal. Bureau of Mines in cooperation with the United States Public Health Service in the Jop-in (Mo.) mining district." As only a few men were examined at that time, it was decided to ore tr.t ir.te ot eS -'v to r. voh' r`" i'Jn 55 a v-'^le experience--: by Amcrst, .. J-a"d-coa; miners is clear from the l?5 :r-adi- by the Public He:.!::: Service.* examine a larger number to gain a more .uvurn:e idea of the prevalence of consump tion among the miners of this distri". Prom . J*:X' s8 -\ V 11 WO ( vS 11 -- V.. j, 1 : 1 j! - z o u r3 ml* N 3 -- */o> 6 2 to 'o,,* \ro> <N , I? wvOo o t/" in, J1 o A = 1 ,25 55 20 55 20 25 29th Xational Safety Congress <N cCWOs |--S. o' *c -- -r -s o--o *r ~--ri r*s -o oi t r* {h -s, IW 50 rsoj CfsM* oo' 4-- I'svj Zl O1/s -o' to -d -ooo* <N (N, so C> 12 1C -- -- t--/J* nc' -T < *o-wr' N. 9C cc >o Cs| --fo* X -t+Oy ts* -S -o' -- wS o, * * KTi ** - - A -- t/i 5 **" US4> 175 yr. =__i <z 5 2 May 15 to December 31, 1915. 720 miners were examined: 45.7 per cent had silicosis whom " j*reulosi and tuberculosis and 5.3 per cent had tu expected berculosis.1* A later report (1917) of this ihe expc same investigation by Lanza and Childs2 jfid eigl included the results of the first detailed jmong X-ray studies of silicosis made in the United covering States. times as Investigations of mining conditions by Harrington and Lanza" in Butte. Mont, a 1921, revealed that 42.4 per cent of 1,018 miners examined showed definite signs of lung damage due to dust. From July 1, 1927, to June 30, 1932, the , ad and An an. Saranac of 5,000 halation dust shov tuberculo Metropolitan Life Insurance Co., the Tri- of reacti< Statc Zinc & Lead Ore Producers Associa of miner tion, and the Federal Bureau of Mines op*' in appro.' crated a cooperative clinic at Picher, Ok3i,a first stag- to demonstrate to industry a workable second st. method for diagnosis of silicosis, to educate . third stag workers in preventive measures, and to serve as a model to industries presenting a . Prevent dust hazard. Of 27,553 individuals exam*.'j ined during this period 5,366 had silicosis^ The da- 742 silicosis plus tuberculosis, and 320 tin-t a the gr complicated tuberculosis. .; mortality' meed in The chief cause of disability in silicosis it . dust as li tubercle infection. The silicotic lung appears silicosis, to be a more favorable medium for the / preventin: growth of the tubercle bacillus than the^' far as pc norma! lung, not because it is fibrotic, not (tntrai'or, because its lymphatic drainage is interfered the work, with, but because it contains silica.'* Ap- propertie- parentiy silica dust possesses this character pacity to istic of increasing tiie liability to pulmonary composit: tuberculosis. That this is true is indicated tmosphc by the statistics quoted in this paper which Particle si indicate also that silica dust increases the liability to other respiratory diseases. Table 9.) Althou-. breath li sted by The results of virtually all studies are jo J higher agreement regarding the high mortality r* msi!icco from tuberculosis for industries in 'vl'a ral p0pu large numbers of men are exposed 10 in tr silica hazard. These rates arc so high they leave no room for doubt of the ca"`f(j and-cffcct relationship between the 3 and the high mortality." Joint studies made by the Actuarial - j Proportio: luartz, 'be finer tnough c. ** defe, cicty of America and the Associa 10 Life Insurance Medical Directors re' ` that there were 65 deaths where 6 "e . pccteda (taobout 1it1 times tmhe expccte ,,mane her) from tuberculosis in 1925-1936 ^ 0{ \ . The pr ;,!nftion . pricing Host, :ts 'Ontro: a group of underground miners, 1 Mining Section 537 her 31, 1915, 720 mintrs '\7 per cent had silicosis nd 5.3 per cent had tu;r report (1917) of this by Lanza and Childs ,ts of the first detailed iicosis made in the United I -hom were employed in metal mines. Tu* tei, deaths were fourteen times the ^oected among copper miners, nine times Ae expected among gold and silver miners, d ei?ht and a half times the expected ^one iron miners. In an earlier study*0 verine the years 1915-1926, there were 18 times as many deaths as expected among i mining conditions bv anzau in Butte. Mont., b X 42.4 per cent of 1.01S showed definite signs oi 0 dust. )27, to June 30, 1932, the Insurance Co., the Tri- 1 Ore Producers Associa;ral Bureau of Mines opvc clinic at Picher, Okla.,1 to industry a workable jsis of silicosis, to educate entive measures, and to to industries presenting a : 27,553 individuals examperiod 5,366 had silicosis, s tuberculosis, and 320 un* rculosis. ;e of disability in silicosis is i. The silicotic lung appears "avorable medium for the tubercle bacillus than the because it is fibrotic, nor atic drainage is interfered _* it contains silica." Ap se possesses this character* ; the liability to pulmonary it this is true is indicated luoted in this paper which x silica dust increases the respiratory' diseases. '^d and zinc miners. , An analysis by the field division of the Saranac Laboratory" of the roentgenograms of 5,000 white miners exposed to the in halation of harmful concentration of silica dust shows that the incidence of pulmonary tuberculosis lesions increases as the degree of reaction to dust progresses. In this group of miners tuberculous lesions were found jn approximately one-fourth of those with first stage silicosis, onc-half of those in the second stage, and 65 per cent of those in the jbird stage." /Prevention of Dust Diseases in Mining C..The data given in this paper point to dust Ss'the greatest contributor to the excessive itortality from pulmonary diseases experi enced in the mining industry and to silica dust as the immediate cause of the disease silicosis. Therefore, the principal method of preventing these diseases is to eliminate as far a? possible or reduce to harmless con centration the dust in the breathing zone of the workers. Experience has shown that the properties of a dust that determine its caPKitv to produce injurious effects are its composition, the quantity suspended in the Jtmospnere breathed by the worker, and its Particle size. Although any dust may be harmful to breath under certain conditions, as indi cted by the data presented here that show virtually all studies are" J higher incidence of pulmonary diseases in ling the high mortality :.s for industries in "uj if men arc exposed ^ r-onsibccous dusty industries than in the genral Population, physiological studies reveal jkt, ir. mining the harmfulness of a dust is iicse rates arc so high ->i7i for doubt of the ca. Lj inship between the ha ^Pornonal to its content of free silica or tfc13^2' in part*c-es small enough to enter * -y-r spaces of the lungs, and in high tality.** concentration to overcome the. nor- node bv the Actuaria:a and the Association Medical Directors re'^ o deaths where 6 'r 1 times the expeej^^ T:en'cs of the respiratory system. The :ur,c;;. prevention of dust diseases is the * oi the physician and the engineer. dm? together to determine the extent of - azard in industry and method* for cubs:? in 1925-1,..*; erground miners, The first step is to determine what 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 for 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 but 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 silicons 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 (he practicability of using a defi nite dun concentration as a guide in setting allowable limits of air dustiness in the pre vention of 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 -ui l9lM.M3.(See Table 10.) Ti:e incidence rates for silicosis uncom plicated by active tuberculosis among South African miners in 1936-1937 was between 8 and *cr 1,000 per annum." The liability among the whole body of miner* to con tract :.:c disease in 1936-37 was loss by 65 29th Xatioiml Nj/y.'v Conorcss Table 10.---Average Number of Miners Examined Annually and Production Rat for Silicosis in Each Triennial Period Since 1917-18 4 Table H Mixed Dt Period Average Number of Miners Examined Annually Production Rate of Silicosis per 1.000 Period Average Number of Miners Examined Annually Production Rate of Silicosis per 1,000 Ay, Mini I917-2U 1920-25 l`"3-2o 14,070 13,260 12.523 21.95 19. H> 53.28 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 1935-36 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 hard coal miners silicosis was not found in a control group of mining employees whose dust ex posure averaged less than 5 million particles per cubic foot of air. The prevalence of anthracosilicosis among the entire group of employees was found to he 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 S 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 tho_S,,cxposed..to 200 to. 299 millionparticles, and 53 per cent of the men who had worked for this period in more than 300 million particles per cubic foot, devel oped anthracosilicosis. 1926-29 1929*32 1932-35 14.624 16.774 20.139 21.11 U.87 9.59 Among men employed for more than 25 years in dust containing less than 5 per cent free silica, the proportion of persons ioiaul with anthracosilicosis under different coneentrations of dust was as follows: 5 to 99 million particles, 7 per cent; 100 to 199 mil lion particles, 54 per cent; 20Q to 299 million particles, 71 per cent; 300 or more million particles per cubic foot, 89 per cent. 0-9: Number < Number < Percent 10-24: Number t Number c Percent * 25-49: Number c Number c Percent w 50 and over Number c Number o Percent w With the exception of miners, their help ers, and rock workers, about 25 per cent of all the men employed underground devel 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 amongpersons 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 ot determining safe limits of dust exposure in* | dicated that employment in an atmosp. containing less than 50 million dust Par.tl,.|e per cubic foot would produce a HfShS1. number of cases of anthracosilicosis '' the quartz content of the dust was 1 5 per cent. In the gangways where the si ^ j content of the dust was about 13 Per..,-rt, a safe limit appeared to be 10 to 1,51 particles per nation for r it 5 to 10 m air. Similar Public Heal; pwomoconic workers. (S- The relati< irnion and c ceitage of v eoniosis wa? worked in million par: 9 per years, 20 per IS years, an those who v t{on of 25 rr Pneumoconio pears, am those who h eentration of 17 cent had Per cent i: The data o Irs<1cs, anthr manufacture, *(T1 treated folded simil: :ir. Mining Section 539 action Rate, ble ii.--Pneumoconiosis Cases Occurring Among 798 Workers Exposed to \r*ed Dust, Classified by Average Dust Concentration, Length of Employment. * 1 and Number of Workers Exposed Production Rate of Silicosis per 1,000 Average Dust Concentration (Million Particles per Cubic Foot) 0-4.9 Years in Industry 5-9.9 10-14.9 15-19.9 20 and Over 21.11 13.87 9.39 '0-9: . .. Number of pneumoconiosis cases. Number of workers exposed......... Percent with pneumocontosis-- .10-24: .. Number of pneumoconiosis cases. V Number of workers exposed........... more than 25 than 5 per cm persons found different conollows: 5 to 99 100 to 199 mil. Percent with pneumoconiosis......... 25-49: Number of pneumoconiosis cases. Number of workers exposed........... >9 Percent with pneumoconiosis......... 50 and over: '.Number of pneumoconiosis cases. 0 to 299 million 'n'Number of workers exposed............ >r more inillia ^-Percent with pneumoconiosis......... or cent. .v.v- , '.4. tiers, their hdpit 25 per cent of g- erground devd- .^particles per cubic foot. The limit of toi- a working period jVeration for rock workers was set tentatively s group was * *at'S to 10 million particles per cubic foot of .lartz content of Vair. Similar results were obtained by the iPublic Health Service in an investigation of osilicosis amonj d for more tha* ch about 35 prt rom 10 per cert :d in concentra- "pneomoconiosis among mica and permatitc 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 a\ particles p years, to 92 been empkjTi coniosis was as follows: Of those who had worked in an average concentration of oO ntiliion particles of dust per cubic foot of dust concent?* n particles IP ; years of "'t"0 a,r. 9 per cent had pneumoconiosis in 5 years, 20 per cent in 10 years, 50 per cent in 1$ years, and 66 per cent in 20 years. Of those who worked in an average coticer.tra* "on of 25 million particles 10 per cent had Pneumoconiosis in 10 years, 27 per cent in a Pears, and 33 per cent in 20 years. Of wse who had worked in an average con- ( ^entration of 10 million particles of dust. 7 ^rcent had pneumoconiosis in 13 years and I cent in 20 years. (See Fig. i.) f The data obtained in other studieVoTcfusty "cs. anthracite mining, asbestos textile -.^ctnre. and the pottery industry have . treated in a similar fashion and have V,- ^ similar, although usually less rs-gu- rC'iiit. Tim position of the ihn--: '!! 0 SI 0% 0 123 0% 0 43 0% 0 45 0% 0 56 0% 0 94 0% 0 45 0% 4 44 9.17c 0 29 o% 0 66 0% 3 31 9.7% 5 25 20.07 0 13 0% 2 29 6.97 3 11 27.37 4 S 50.07 0 s 07 4 23 17.47 6 IS 33.37 4 6 66.77 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 tlie regularity ot 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 be advisable to set up any mathematical treatment because, of all the men who entered the industry, only -.he survivors have been studied. There is no adequate wav of finding out whether or not men who dropped out of the industry v.ere in a better or worse state of health a:'ar as silicosis is concerned than men who remained in the industry, and thu< there i5 .o way of introducing a correction for thi nn-ni <<i selection into a mamemati'-s! :*''*'*'- *>?r%*5A-- 'V<. ..i-*.*. ^a**c-?s% 'V.'v &i -iwtAlifr., -- jLb '. n.-^.<-r iLA &*STi A5-i *; . j>SAfe-|St*iS?VfcAVSt >-.!;. if IfriMaifei iA fell ti&k 4 i:;j n-vir Mm jiiL If! Iflpeiii.; 1$Si}ytf* fcfflli tah IPIf)-!'-' i its JIl 540 .?9//i Xational Safety Congress Shovelers men).. Shovelers Drillers' 1; Trackmen Roof trim Figure 1,--Relation of average dust concentration and duration of dust exposure to the percentage of workers found to have pneumoconiosis. Based 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 tiiat the principal use of these data is to show the 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 occupatioits, the number of persons in each, and the various activities and time devoted to each acti-. ity in any one occupation.2* The amount of harmful dust created by various activities can be determined by tak ing samples of the atmosphere in their vicin ity and counting and identifying the dust particles. Sampling of air Is.also a means of checking thcTifflciency o'f any control meas ures that may be adopted. Several devices are available for collect ing and counting dust samples. The im- pingcr, however, is the instrument used most frequently in the United States. The Bureau of Mines and tiic 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 and identifying the particles." B Dust sampling is complicated by the 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 of the average ex posure of the worker over a period of years, especially if he has not worked continuously at one job. The ultimate lung injury dial he may suffer will depend upon the inte 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 of an operation and, with the aid of a time study, break down the worker's day according to the time spent in each step; from these data the average dust exposure c: the worker can be calculated. Drilling.--Experience in South Jl*"r'c.a. with new methods of sampling have revoa that more dust is produced by rock dn than had i listing cm tected by t of control the prcvci by the fac: remained higher ann those who the excess has been ir of time spi Until rel for blastin. dust or air other than operated au dust, hut \\ mining pow more cssent producers > especially ti jackhammer compressed in coal or i: Blasting.dence of siii the early pc: South A of the rockdust but to I blasting, and drying amo duced by bis Masting then Quantities of lions of wltii jhe mine air ventilation Shoveling 0lda., study.' rdationsliip < t'.'r Mining Section Table 12.--Period Worked at Face by First-Stage Silicotics Average Number Average Number Job Number of Job Number of of Years Men of Years Men Shovelers' helpers (bruno Drillers' helpers (dummies) Trackmen............................. Roof trimmers..................... 6.8 8.4 S.4 9.8 11.3 Machirtemen (drillers)... 11.4 8 11.5 428 15.8 79 Ground bosses................... 19.0 52 1 26 1 348 24 21 54 nd duration of dust exposure oconiosis. Based on data pre- ever, is the instrument used most in the United States. The Bureau 3nd the Public Health Sendee .d publications describing the sampling dust by the impinger - by other methods) and pror counting and identifying the pling is complicated by'tbe fact tstmess fluctuates rapidly from moment. A single dust count rep- tiic amount of dust in the at t the time and place of sampling no indication of the average e.v;:c worker Over a period of years. : he lias not worked continuously The ultimate lung injury that :f7er will depend upon the inte nt of the dust over a long period.' measure of dust exposure cturc of the variations in dustt- best procedure is to determine ss during different stages ot an .nd, with the aid of a time studyu the worker's day according 10 cm in cacii step; from these da*a .* dust exposure of the worker --Experience in South .Africa, vthods of sampling have revealed Pi't is produced by rock dr;--' 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 Ahose 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 compressed air in the clearing of holes either io coal or in roof or floor material. Blasting.--The exceptionally heavy incifence of silicosis among rock drill miners in {he early period of the gold-mining industry m South Africa5' was due to the exposure of the rock-drill miner not only to drilling bm to high concentrations of dust from lasting, and frequently to the inhalation of frying amounts of the irritant fumes pro duced hv blasting, owing to the method* of oUstin^m,... in-vt-rt. --I4!rsstmg produces large Quantities of very fine dust, the finest frachons of which tend to remain suspended in !"* mine air for a lone time, unless remove-! ventilation. ,'j- M'.u'k'inn.--In the Picher. ' study." it was diitVuh to show the -atioi-cj'ip .|1C duties of the men to 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 shovclers1 helpers, shovciers, drill helpers, machincmcn, trackmen, roof trimmers, powdermen, shovel bosses, and ground bosses. According to analysis of the occupations of face workers the hazard was greater for shovclers' helpers and shovelcrs than for machincmcn if length of time re quired to produce first-stage silicosis is a criterion. It is noted from table io that the average number of years worked by shovel crs' helpers and shovclers was 6.S and 8.4 years, respectively, while that for machinemen was 11.4 years. Loading and Hauling.--Under some con ditions hand loading ot coal throws into the air of the working place considerable quan tities of dust, but the amount is about onetenth that caused by some types of mechan ical loading. The greatly increased occur rence of dust from mechanical loading is cine not only to the stirring of tltc 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 o; rolling equipment or the hoofs of- mules ar.d then to he thrown into the air by *pced::vc cars or shuffiin? nudes or men.5' i- Kim 29th Sationai Safety Congress Where conveyors (cither the shaker 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 off 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, sitcaring 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 generally accepted 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 tance, the^main' features that affect air in metal mines are (1) movement, (2) tempera ture, (3) relative humidity, (4) gases, and (5; dusts. Jn coal mines the order of ponance would probably be (1) movement (2) gases. (3) dusts, (4) relative humiditv' and (5) temperature.11 The matter of movement of air from the surface, through the working faces or places, and then back to the surface is by ajj means the most important consideration in effecting adequate ventilation of mines and in protecting the health and forwarding and maintaining the working efficiency of the 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.** Ventilation probably is the most effective dust-control measure although under some conditions it ranks second to wet methods. Where ventilation can be applied effectively, dust can be removed from the air or its con centration can be so diluted as to render it almost harmless." IVet methods.--As dry drilling is the dustiest operation in mining, wet drilling will keep air dustiness within safe limits if used with care and judgment in collaring wet using plenty of dean, dirt-free water, and keeping the drills in good repair with ade quate regulation of the proportion of water', and compressed air flowing through the drill steel. In tests by the Bureau of Mines* the dust concentration in the air during actual drill ing decreased as the water flow through the drill increased. The water flows for stopers was 0 to 3 gallons per minute, and that for drifters from 0 to 1.02 gallons per minute. The rate of decrease for stoper drills was greater for water flows from 0 to 1.3 gal* Ions per minute than for higher water flows. The rate of decrease for drifter drills was similar to that for stoper drills at cor responding water flows and rather constant for water flows* of 0 to 1.02 gallons per minute. j .-fiH'.id1 tin <.:r:I- .-iccl wi: ' .,filv some o: the high ."ftj fi> the for i<\- :ll0 the back cud ot th -*hen operating thre jawing position, and tra- 0t the hole being drilled, piping is affected b> trough the drill steel; trough the drill steel im ^creases. Mining officia (oncluded that such air probably facilitating retr of the cuttings from the jjble tor entrapping fine it into the air during Quently they have devote designing drills that pc practical air leakage thr md have established reg of such drills. Canada Kork along this line, ittte that such drills arc duce about one-fourth : don of corresponding Mustless-hcad" features.1 The results of this s' crators can reduce dus' suiting from drilling rater flow through the increasing water pressu; .rater tubes of larger in ; Tests also have bea Bureau of Mines" on spraying water along th< steel compared with th drilling practice. The U water along the out: should not take the p' drilling. However, if a V which the device m 1 any inclination, it i valuable accessory to r< glaring and drilling ; We. Tests show that dust is thrown into &kce in drilling the fir The results of this study shows that as water flow through the drills was 'ncreas*f the dust concentrations in the air decreased, hut they do not show whether the ^ccreV was caused directly by the increased %va. flow, by some condition influenced.by van tion in water flow, or by a combination , Wet drilling standarc ![> Mew York State fe 'asses of rock. The r. in Class H rock ( 'an 10 per cent frelrs, which include t ventilation, are quoted ' these factors. In most pneumatic rock drills air Pa*-e h "Wet drill'irtg--5fia Us application of wat- *2* Mininy Section 543 the order of be (1) movement,, relative humidity :\t of air from the 'orking faces or e surface is by all it consideration in :ion of nines and id forwarding and efficiency of the adequate quantities a the places where requirements of iemands of safety the most effective .ough under some 1 to wet methods, applied effectively, n the air or its con* ted as to render it -y drilling is the r.g, wet drilling will safe limits it used in collaring wet. -t-free water, and 1 repair with adeoportion ct water g through the drill i Mine;2 me dust uring actual drill flow through the flows ter stosxr* nute, and trat fof allons per minute. stoper drills v** rom 0 to 1-3 S2'' igher water drifter drill-1 "'i` er driils at cor' ,d rather ccr.sur- 1.02 gahons [<' ly shows that a* iils was ir.crea^ the air Ji-crea^ .ther the c*a > a increased "'a!4' :;ucnccd v2r"`. a combir.atto" 1 : drill- Is*4 jWul, the drill steel with the water. Ordisome of the high-pressure air sup- zM to the drill for its operation escapes Sato the back en<* * steel, even 5ten the operating throttle is not in the -Rowing position, and travels up to the face Sy the hole being drilled. The amount of air 'ecap'n lS a^ectet^ by the water flow through the drill steel; as the water flow -iirough the drill steel increases the air flow decreases. Mining officials in South Africa ''bcncluded that such air leakage, although probably facilitating removal by the water >f the cuttings from the hole, was respon se for entrapping fine dust and blowing 31 into the air during drilling." Consci^eentiy they have devoted much attention to 'designing drills that permit the minimum practical air leakage through the drill steel and have established regulations on the use ${ such drills. Canada is also doing much work along this line, and recent reports state that such drills are practical and pro- -duce about one-fourth the dust concentra tion of corresponding drills without the "dustless-head" features." . The results of this study show that op'tntors can reduce dust concentrations re sulting from drilling by increasing the water flow through the drill steel, either by increasing water pressure or by the use of water tubes of larger inside diameter. Tests also have been conducted by the Bureau of Mines" on the effectiveness of spraying water along the outside of the drill steel compared with that of standard wet drilling practice. The tests show that spray- water along the outside of the drill steel *hould not take the place of regular wet drilling. However, if a method is developed ky which the device may be used on holes ot any inclination, it might prove to be a salable accessory to regular wet drilling in ^faring and drilling the first 2 feet of a Ti;$ts show that the greatest amount : dust is thrown into the air of a working "2fe 'n drilling..die first 2,feet of a hole." drilling standards have been adopted acw York State for drilling in various v.3''45 ot" rock. The requirements for drili'4 m Class 11 rock (rock containing more iT!? ^ f'cr ce,u rrc< s'hca) >n confined V'bich include the use of mechanical '"hlation. are quoted below." ,J` Wet drilling shall mean the cv.minu- aaplioatinn of water through t!u- central hole in the hollow drill steel to the bottom of the drill hole- The central hole in the steel shall not be less than A" diameter. 2. "The water flow shall be maintained continuously whenever the drill is in opera tion, including the period of collaring orstarting the drill hole. The valve in the water line shall be of such design that it has. only two fixed positions, namely, dosed and compfetely open. Six months after date of approval, all wet drills shall be equipped with a combination air throttle and water valve of such design that the required rate of water flow through the drill steel will be insured whenever the air throttle is in the operating positions, half speed as well as full speed. 3. "The water shall be dean and bacteria free and shall be delivered to the drills under pressure from an adequate source of supply. Portable water tanks for individual drills shall not be used unless approved by the In dustrial Commissioner. "Wet drilling in Class II rock in confined areas shall be used with mechanical ventila tion, or in confined areas under decking by natural ventilation, if approved by the Indus trial Commissioner and subject to the fol lowing provisions: 1. "The rock surfaces for a distance of 30 feet from the heading or other drilling area shall be maintained in a damp condi 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 half-speed operation. 1.0 cubic foot 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. 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 Tlrr-.u-c!' Steel.' 4 4. "In the case of poitive-pre$ure ven tilation. the air must be w;|] distributed i.wr tin- drilling and mu-t n<>t create drafts. *if*ft;V^':'--w-vprv--.- 544 29th Xoticwal Safety Congress at the various drilling positions, in a man ner satisfactory to the Industrial Commis sioner. The intake for 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 2one 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 by Rule 33-2.3." Proper blasting practice.--Methods of controlling dust and fumes in mines by proper blasting practice have been deter mined hv 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 or 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 of Mines** show settling rate of dust af^r blasting under the following conditions: 1. The atmosphere was bratticcd off 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 SO million particles per cubic foot. 2. The atmosphere was bratticed off until '26 minutes after blasting when the practice was raised and natural ventilation (which was virtually negligible except for eddy currents was allowed to dilute the dust laden air. Tt 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 until 37 minutes after blasting, when the brattice was raised and 10-inch canvas tubing installed to about 50 feet from the face. At 46 minutes after blasting, about 1,000 cubic feet of air per minute was forced into the face. It required 66 minutes after blasting tor the dust concentration to drop to ?Q million particles per cubic foot, and 70 minutes to drop to 15 million particles per cubic foot. The accompanying table shows the time, in minutes, required for the dust concentra tion to drop from S25 million particles per cubic foot to 50 million and to 15 million particles per cubic foot under the three differem conditions: ,!ry. In y itoiv daste-' will b:nd t! johonmetho reduce oi ga- necciw -icmm now a :he c\ ind rand a' Time, in minutes, to drop from 825,000,000 Ventilating particles per cubic foot Condition No ventilation........... 121 1S1 Natural ventilation.. . 105 135 Mechanical ventilation 20 24 In addition, the place (walls, floor, roof :>r top, and timbers) should be wetted thoroughly before blasting is done, and a .vater blast should be used during and after the blasting. The region should be wetted thoroughly when the men return to the face region after blasting, and the muck pile should be kept well wetted at all times while it is loaded out, as the water not only lays the dust but also either absorbs of otherwise aids in diluting or eliminating harmful or poisonous gases that fo``* blasting and that usually cling to the blasted natcrial. Tests*1 on die effectiveness of a spray of water mist in reducing the concentration o dust in the air after blasting and dunng mucking of the blasted material "ercJw0 ducted in three headings in medium hart hard rock. The use of the spray aPPare""i made it possible to reduce the concentra ^ of dust generated and thrown into-l during blasting more than 99 per ccn ^ the amount present when the spray " used. Dust dissemination during of material sprayed several hours mucking was begun was much eSoUgfa|r during shoveling of material 1 lor . sprinkled just before and during and, of course, the dust present at e either the spray or the sprinkling m . Mining Sccli<nt 545 1C tV i*-s iba*i it the muckinu had been done Jtf- In general, the larger the quantity ot c.xJ Ye used, the more finely divided the material, the more heavily the air impregnated with dust and smoke. *\ the greater will be the quantity of jSonous gases left at the place; hence, B^thods should be used that will tend to iuCe the quantity of explosives used and ya<c> and dust produced. In this con- n^tion *t "-ill be found that the use of gemming or of some types of blasting plugs available will confine more definitely jbe explosive, hence, increase its efficiency ind reduce the quantity of explosive, used and also reduce the amount of poisonous ps produced and possibly reduce the vio lence of the blast and its tendency to raise du.q and dbseminate it into the surrounding ,ir. It would be well for users of explosives b investigate types of explosives that are Vnown to give oft minimum quantities of .brmfu! gases on detonation, and to use them; also, the discontinuance of the use of fuse and the substitution of electric blasting vould aid in reducing the amount of poison ous gases from blasting. Explosives that have been held in Aorage too long or that have been stored under unfavorable condi tions as to moisture, temperature, etc., are 5kc!y to give off maximum quantities of harmful gases, it they detonate at all; hence, utmost care should he taken in 'the storing of explosives to see that they are not held too long before beinu used. I'irsoiiii! r\s/'frit:.r fr.wvfmu. -- This method of control of air dustm.ess is unsat isfactory in underground minir.c except for temporary u.-e in cmcrgcncis-. Although fa<t respirators give adequate protection against dust, they afford the wearer essenually no protection against :ex:c or asphyxuting gases. and are too cumbersome and ^comfortable for constant wear. The Bureau of Mines has established a c-iedule oi minimum requirements for ycchanical respirators, one tyre oi which is jr Protection against dust generated by dis-Jcgration as in drilling ar.d blasting. 30 re-piratc-rs have 'een approved 'rAi: tfM-s <ci-.cduk-. Pkv*ic<i! ,'.v,iu3inii::oji --A'.t.hough _ strictly dicing physical exammat:: r. :? not a dust- .'trol measure, it is an i;n:',r:ant means of '^stninc- the crffcacv <: methods em- ployed 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 are examined and certi fied to be physically fit and free of 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 pneumoconiosis and the extent of impairment of working capacity among employees from year to year. Com parable records will not be obtained unless periodic examinations are conducted in a standardized way, preferably by a permanent medical hoard composed of physicians spe cially trained and having adequate experi ence in the diagnosis ot pulmonary diseases. Summary 1. The principal pulmonary diseases to which the miner is subject are bronchitis, influenza and pneumonia, pulmonary tuber culosis, anthracosilicosis, and silicosis. 2. Statistics indicate that much higher morbidity and death rates fr<m pulmonary diseases arc experienced in dusty than in nondustv industries, especial;;.- where silica dust is used or produced. 2. Investigations by the Public Health Service reveal that hard-coai miners suffer a high mortality rate iron: influenza and pneumonia not only during influenza epi demics but at other times as well. In 191523 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 mates at ages 15 to 65 who were engaged in pursuits other titan coal mining. Six per cent of hard-coal miners had pulmonary tuberculosis com pared with 2 per cent in the adult male population of the United States. The rate for metal miners is still higher. 4. Anthracosilicosis was found in about 23 per cent of 2.711 employees -of three anthracite mining companies studied by the United .Stare* Public Health 5erviee in lOAv tm M: Ah-t : .aif cSk."Vi T'fcfi Mi Mil if -fipn m `iM m 33:' lll|33 Sfi*fe* m 54b 29th National Safety Congress About 63 per cent of those having anthra- cosis when the quartz content of the duM cosiiicosis showed evidence of disability, ;e>s than 5 per cent; when the silica COn' 1. Co'.liv compared with less than 10 per cent in the tent is about 13 per cent 10 to 15 mimj ;J<`: Bull. control group. Moderate and marked de particles appears to be a safe limit. >. Coliii. crees of disability handicapped approximatcly 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 (l) rock workers, (2) regular miners, (3) all others exposed to more than 10. The amount of harmful dust create by various activities in mining can j termined by sampling the atmosphere jr their vicinity and counting and identityinthe dust particles. Sampling of air is also! means of checking the efficiency of dust con! trol measures. 11. The impinger is the dust-sampling ;(l. ;;i-< ol Bt ie.(in:orY .. [033-24. 3. Coliii lied with i- Occupatk Jniiti: Silic S13. P|>. 39 = 1, Bruntja; ,'a'tied Stair 100 million dust particles per cubic foot of -trumem used most frequently in the I'uiieri Office c air, and (4) men in haulagewav? except States. i Health 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. jjosure to 12. The dustiest operations in mining arf 'abiic Heali dry drilling, blasting of dry rock or ort. i Sayers. shoveling or mucking, loading 3tid haulage, nd Adai and machine coal cutting. llaoftK Mine :*U. Kansa far 30. 19.' )3. The principal measures for controllim* >JJ. 30 pp. Joint studies made by the Actuarial So tiie ill effects of dust in mining operation, /. Dublin, ciety of America and the Association of Life are ventilation, wet methods, proper blast .sal Miner* Insurance Medical Directors'0 revealed that there were 65 deaths where 6 were expected (about 11 times the expected number) from tul>erculosis in 1925-1936 among a group oi underground miners, most of whom were employed in metal mines. Tuberculosis deaths were fourteen times the expected among copper miners, nine times the ex pected atnong gold and silver miners, and eight and a half times the expected among iron miners. In an earlier study" covering the years 1915-1926. 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 mining industry, the prin ing practice, the use of personal respiratory j-* December protection, and physical examination of IL 1919-20- p. workers. t Colli-., iealth, Di- 14. The efficiency of these measures in the *!usl Hvp reduction of the incidence of dust diseases 9. Sen. 1- xsth Wale- is attested by the experience in the mines of 5bercuig>is: South Africa where among the whole body * -Vs-237. of miners the liability to contract silicosis in 10. Office - 1936-37 was less by 65 per cent than it was vibrato-Sib in 1920-33. Among the "new Rand miners State who entered the industry- by way of initial h. 1-anza. examination since 1916 and who have Ixxr :n*ey Di- exposed solely to the progressively improv ''net. Mi- ing occupational conditions that have ob tained since tiiat date, the liability to con tract silicosis was less by 87 per -cent than the similar liability among all miners work ' Miiie'b 48 pp, W Harrin "'-sumption :ru of .V cipal method of preventing these diseases is to eliminate as far as possible or reduce toharmless concentrations the dust in the breathing zone of the worker. ing tor an equal period in 1920-23. The* "new Rand miners" constituted 77 per cert of all working miners examined- .'3- Robert " 'nine Re, ;;; Col '*2. *' t-anza. 8. The aim should be to eliminate the dust entirely from the air breathed. Where this Conclusion ,;is: Oti J5'C.,Ui>, is not always feasible it may be possible to reduce the dust to a concentration that will not cause disability during a working life The mortality and morbidity from.pid monarv diseases arc cxcessive-i^-the industry as a result of expo-mre to la of tndu.i. time. amounts of dust in the air breathed. ^ 9. Analysis of data collected by the Pub fore, control of the dust hazard i:e^c^ lic Health Service to determine safe limits ot 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 to prevent these diseases. N'o single of control is applicable to all dti>t} tions and processes, therefore, all the of prevention must be practiced to ifl- . success in the solution of the problem. If ) Mining Section 547 REFERENCES Edgar L. Occupational Dust DtsvV.*- 7gull. Hygiene, vol. 6, 1931. pp. 663-670. r<j|is. The General and Occupational Prevai * - Bronchitis, and Its Relation to Other 'fc**. ,-fv Diseases: Jour. Indust. Hygiene, vol. : J'&SVpp. 264-276. i Con1a1'i The Mortality Croup Exposed Experience of an Octo Silica Dust, Com- t!!!j,V*-ith that of the Ceneral Population and ^Ortupational Croup Exposed to Dust Not Con- ** . Silica: Jour. Indust. Hygiene, vol. IS, Bnandage. Dean K. Mortality of Coal Miners: Stated States Public Health Bull. 230, 1933, 17 pp. ' office of Industrial Hygiene and Sanitation, fte Health of Worker* in Dusty Trades. Ill entire to Dust in Coal Mining: United States Health Bull. 208. 1933, p. 10. -ASayefS. R- R * Meriwether, F. V., Lanza, A. t and Adams, W. W. Silicosis and Tuberculosis Miners of the Tri-State District of OklaKansas and Missouri--I, for the Year Ended hot 30. 192S: Bureau of Mines Tech. Paper S4S, H33, 30 pp. T. DuWi. Louis 1. The Mortality of Bituminous Miners from Influenza-Pneumonia, October December, 1918: Jour. Indust. Hygiene, vol. (. 1919*20- p. 4S3. in ll* g. Collis. Edgar L. The Coal Miner: His Keihh, Diseases, and Ceneral Welfare: Jour, (odut. Hygiene, vol. 7, 1925, pp. 221-243. ..Sen. Prafulla Kumar. Pneumoconiosis in Soei Wiles Coal Miners and Its Relation to Tuberculosis: Jour. Indust. Hygiene, vol. 19, 1937. iev 225-237. - 10. Office of Industrial Hygiene and Sanitation. Aainco-SiiicO'i'. Among Hard Coal .Miners: Ceiled States Public Health Bull. 221. 1933, 114 t* ` 11. t-anza. A. J., and Higgins, Edwin. PulScr-ary Disca-e Among Miners in the Joplin IbV.nct. Miouri and Its Relation to Rock Dust a tie Mines: Bureau of Mines Tech. Paper 105. I'd:, 43 pp. 12. Harrington, D.. and Lanza. A. J. Miners' fesvistpnon in the Mines of Butte. Montana: tattau of Mines Tech. Paper 260, 1921, 19 pp. : 12. Roberts. John. Silicosis: A Review is Given j *1 Recent Researches on the Cause of the I *'*: Collierv Guardian, vol. 147, 1938. pp. 23*r-2. D. Lanza. A. J. (Editor). Silicosis and A*w':c-:: Oxford University Press. 1933. 439 pp. L. Colli-, Edgar L. ' The Statistical Cbaracof Dust Phthisis (Pulmonary Silicosisi: Ithlut. Hygiene, vol. 5, 1926. pp. 457-465. Hiccu-.s, E.. Lanza. A. J., L.iney. F. 13.. and -w' *' siliceous Dus: in Relation to Pul- D:ea,e Among Miners in the Joplin Dis- 3Iisouri: Bureau of Mine-* Bull. 132, 1937. V." A. J-. and Child*. Samuel B. I. Consumption: A Study of the Disease 1 :j Zinc Miners in Southwestern Missouri, | 0..'>?*nJ*n,Ray Findings in Miners' Consume- r' .U n`ted States Public Health Bull. Si, 1917, IS. Menwether, F. V., Sayers, R. K., and i-anza. A. J. Silicosis and Tuberculosis Among Miners of the Tri-State District of Oklahoma. Kansas, and Missouri. II. For the Year Ended June 30. 1929: Bureau of Mines Tech. Paper 553, 1933, 2S pp- 19. Kettle, E. H. Experimental Silicosis: Jour. Indust. Hygiene, vol. 8, 1926, p. 491. 20. Ijnza, A. J., and Vane, R. J. Industrial Dusts ami the Mortality from Pulmonary Dis ease: Am. Rev. Tuberc., vol. 39, 1939, pp. 419-436. 21. Cumminus, Donald E., Downs, Robert N.. and Berg, Melvin. Tuberculous Lesions in Male Industrial Workers: Am. Rev. Tuberc., vol. 39, 1939. |p. 439-455. 22. Union of South Africa. Report Upon the Work of the Miners' Phthisis Medical Bureau for the Three Years Ended 3ist July, 1935: Pub lished bv the Government Printer, Pretoria. S. A.. 1936. 76 pp. 23. The South African Mining and Engineering Journal. The Incidence of Silicosis: A statistical Examination of the Position--Progressive and Noteworthy Reduction--Mining Industry's Indialive in Investigating the Dust Problem: Vol. 49, 1938. p. 717. 24. Bloomfield. J. J., and DaUaValle. J. M. The Determination and Control of Industrial Dust: United States Public Health Bull. 217, 1933, 167 pp. 25. Brown. Carlton E-. and Schrenk. H. II. A Technique for Use of the Impinger Method: Bu reau of Mines Inf. Cire. 7026, 1938, 20 pp. Schrenk. H. H., and Fetcht. Florence C. Bu reau of Mines Midget Impinger; Bureau of Mines Inf. Circ. 7076. 1939, 7 pp. Ko*ter. Wilder D-, and Schrenk. H. H. Petro graphic Imlentification of Atmospheric Dust Partides: Bureau of -Mines Rept. of Investigation336S. 193$. 10 pp. 26. Drinker. Philip, and Hatch, Theodore: In dustrial Dust. 1936, 316 pp. 27. South African Mining and Engineering Jour- ;il. Miner'' Phthisis and Working Conditions: Vol. 49. 1938. pp. 521-523. 2tt. S.A.M.E. Journal. Future of the Miners' Phthisis Problem: Vol. 49, 1938, p. 13. 29. Harrington. D. Formation, Collection, and Treatment of Coal Dust in Mines: Bureau of Mines Inf. Circ. 7039, 1939, II pp. 30. Davies. A. L. Airborne Coal Dust: Abate ment c: tiie Nuisance in Intensive Conveyor Min ing: Coii. Guard., vol. 153, 1936, pp. 7?5-758- 31. Harrington, D. Mine Ventilation: Bureau of Mines Inf. Circ. 7047, J939, 16 pp. 32. Brown. Carlton E., and Schrenk. H. H. Relation of Dust Dissemination to VVaier Flow Through Hock Drills: Bureau of Mines Rept. d Ir.ve-tigations 3393. 1938, 6 pp. 33. Johnson. John A., and Acnew. Wing G. Dust Produced by Drilling When Water is Sprayed on the Outside of the Drill Steel: Bureau of Mine* Kept, of Investigations 3473, 1939, 6 pp. 54. Industrial Bulletin. Standards for the Test ing of "We:" Drilling Equipment and "'Wet Meth od'" o: Du't Control: New York State Dept, of Labor, vol. 17. 1938. pp. 63-6*. , ii ?;!& i-nm : ?<] m -# Aa ilp . .Viflsd ,;]p ' 3fpj