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P-NSC-9 TRANSACTIONS 29 th ds NATIONAL SAFETY-GONGRtSS GENERAL AND INDUSTRIAL SESSIONS CHICAGO OCTOBER 7-11, 1940 - j NATIONAL SAFETY COUNCIL, INC 20 North Wacker Drive, Chicago Copyright, l?*0. National Safety Council. Inc. Printeo in !*e U. S. A. ; , ciOOOO Contents ai Safety Congress ;y Council, October . Volume I contains of the various In:ne II contains the icrcial Vehicle, the me Safety Sessions. all industrial mem) members who are sessions it contains, may obtain Volume lvaniagcous to dis c's to the individual their organizations, lformation the voltion programs. The lard reference ma ma}- be obtained as. 2 each ; 11 or more ne II may be had at mrd of the pmceedaddresscs and many > delete extraneous rtions. and emphain promoting el'feent prevention metiswhat abridged verir vaiue If) the stu- in achieving more "he original municnee, if desired, in -digresses. seeks to eh are not pertinent " be contrary to the ecept 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 Interestin 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 MachineShop 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 SsxtiiciCiCwGli TV .............................................. 723 Wood Products Section.......................................................739 Safety Exposition Exhibitors.......................................... 743 Index ........................................................................................ 749 v-''' ' i'. -.-Aw r- .-...- : r :fx.' -. <s^>* * ` ;*r>V:-' . .'- i;.;-. ,'-:- -V-::W*-' s-v&sr fl 110 -Wt Xationa! Sa;,-!x Cor.arcss of prompt ami continuous delivery of essen tial weapons of defense %ve must not only train new workers and retrain older work ers. but we must restrain accidents, ni.;^ fritter away our suppiy of skilled handj 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, 1 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 iar a? to the maximum allowable concentration which 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 such 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 they determined the amount of lead in the air of a workroom and matched it up with the record of lead poisoning in that room. In this way they were able to state that, if the 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 s, was not to be taken as safe, only as fret from serious danger. In 1933 our own Puis lie Health Service concluded that tilt amount of lead dust or fumes in the jir 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 must, it seems, be s;ill lower, for some cases were found which had developed even at 12 ag. I believe the next important contribute* in this field was made by the Benzol Cans mittce of the National Safety Coundb which, as you all remember, established 105 parts per million as the maximum allowable concentration for benzol. That figure sdf stands, though we have a good deal of evs1' dcncc that it is too high. You arc probably familiar with two remarkable reporis on in dustrial benzol poisoning which appeared a 1939; one from the Massachusetts State De partment of Labor on benzol in the manu facture of shoes; the other from the Xe* York State Department, on benzol in roto gravure printing. In both studies cases were discovered that had developed after ex posure to concentrations below 100 ppm. A* a result. Dr. Francis Hunter of Boston de clared that, "It is doubtful whether anyc*\ cent ration of benzene greater than zero n sate over a long period of time." The American Standards Association hj* .'ad for some vears a committee on this s American Standards Association Committee Substance Carbon monoxide Parts per Million Length of exposure, IOO ( 400 iNotouerSboura daily Benzol Carbon disulphide Hydrogen sulphide I ! 100 20 20 - .8 .................................. jpet, composed dation engine ritr; and toxic UP standards f u !'h two gas rbon monoknzel and e atJrjF.cd for ; a`companying f>Pm - chiefly l ,n France me. '-T2><T. c-ls.'. Vr-ie; Governmental Safety Service in Industry 111 estraiii accident?, supply of skilled h.nk ..pons. Dangerous Suggested Standards for liliaois and flasssefcosefts Parts per Million Milligrams CubicMeter Substance Illinois Mass. Illinois Mass. Ammonia 50 100 Aniline 55 Benzol .75 .75 , Washington, D. C. Carbon tetrachloride IOO 100 ic. This amount, you stt, ;n as safe, only as frtt .t. In 1933 our own Pub;c concluded that tbt ust or fumes in the aif ' nig. per cubic meter to; n the basis of an investietc battery plant, and i -".303 men employed there. posurc," the figure mutt, wcr. for some cases were .cvclopcd even at 12 mg. xt important contributice lade by the Benzol Com.'ational Safety Counal remember, established 100 the maximum allowable benzol. That figure stfB . have a good deal of evio high. You are probably ` .M l'v_ 'zy Chlorine Chlononaphthalenes Chlorodiphenyls Chromic acid Gasoline Glycols Hydrochloric acid Hydrocyanic acid Hydrofluoric acid Lead Mercury Methyl alcohol Nitrogen oxides (Nitrobenzol Ozone Phosgene 0.35 1000 25 10 3 100 10 1.0 1000 10 10 3 200 10 5, 1 1 5 1 to5 5 1.0 10 0.1 1.5 1.5 1.5 1.5 rcmarkoblc reports on in. zoning which appeared in : Mnssachusetts State De- on lu-iuo! it: the manethe other frsm the Xt" unent, on benzol in roteu botii studies cases were j :ad developed after ex-1 -ations below 100 ppm. 3-- j cis Hunter ct Boston do j doubtful whether any con- j r.enc greater than zero i Phosphine Sulphur dioxide Tetrachlorethane Tetrachlorefhy1 ene Trichlorethylene Toluol Turpentine Xylol Zinc oxide 10 IOO IOO IOO 75 500 IOO 150 2 10 200 200 200 200 200 200 15 -eriorl of time." I Mnnrlards A**ociation s a committs-t on this sz.- )t, composed of industrial physicians, ven tilation engineers, industrial insurance car- ni+tee ners and toxicologists, who arc trying to set I UP standards for use in industry. cf exocsur* bo tar wc have dealt conclusively only wuh two gases and two volatile solvents. r 8 boon 8- - --^.^S^Q^ujcrcxide - and hydrogen sulphide, nzo: and carbon disulphide. The limits a opted tor tlie present are shown cn the accompanying chart. Benzol stands a: 100 ins*71" C-'icny because of the insistence of our sur,,nce members that this is an id'.ai that can be realized practically while a more rigid standard would be rejected, ar.d we should be left with no standard at all. My self. I am always willing to accept half a loaf rather titan no bread, but Manfred Cowditch. of the Massachusetts Eurcau of Occupational Hygiene, is unwilling to go higher than 75 ppm., and Yandcii Hender son. of Yale, enters an emphatic protest against 100 ppm., saying that if 21 ppm. is feasible for hydrogen sulphide a.-.c carbon disulphide, he can see no reason v. hy it is 112 29th Xutional Safely Coiii/res.t Tentative Staadamis Adopted By Public Authorities Tor Maximum Allowable Con centration Of Silica Containing Deists Authority Millions of Particles pwCu.Ft of Air Free Silica Content High National Silicosis Confer I Medium Low aniline and group. We i thc oilier ch CCl-l, aboil! more. A? comes chiefly pharmacologr non-toNic sec fection which (Justrial poisor ence. 1936. Medical Com mittee........---------------------------- 5 ---10 to20--j................... Ditto. Engineering Committee.......5............ 10 to 30--!--------------- U. S. Labor Department | 1936 Division of Labor j Standards.........--.............r--5-------------- 15------ ------------------ NewYork Department gf ____ Labor. 1940................. --'' 10.......j"H00 - Connecticut Department of Public Health. 1936.----- " ---5 ---.............. - Cali/brnia Industrial Acci- , j dent Cbmmission. 1936.---------- 5------------------------- ---50........ . To pass ov, field, silicosis, fact, so eviden that there is s: agreement amc amount of dus V tiotts of free si a workshop. T1 ; ing from gases -! not take fifteen silicosis may. M from the actus affect the dang i>dust. (7 ^f.Take foundty Wisconsin Industrial Coro- j Lt'silica, running : mission. 1932.----.............. 5-..................;------15.......------- --------Massachusetts Department; 2dangerous gran: ,-yhas for centurie: ;ivc*ot jiwuw v.u> II of Labor 6' Industries 1940..... 5.................. 10----- ; --100 -- (granite) _ 25 hffpf'foundry work &of this particula j foundry rf Hatch and Moke, i nuisance rrtion for the dine' Dusts s and other silicio ' .-shown the silica chiefly in the larg impossible tor benzol. Certainly is to be Imped that ventilation engineering will pro gress to tlie point where a lower figure than 100 ppm. may be reasonably demanded fur benzol users. T!:e standard for carbun 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 toxicologists 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 Company.and the Tubize-Chatiilon Company, When it comes to the other :v<:c suh"star.ces i have listed here, we car. ,-iv onlv that the figures given represent our best judgment at the present moment, hut we ad mit that that judgment is oiten based on something not far from guess work. Take tltc one on which I happen to be engaged at the present time, tetracldorcthane. We know it is the most dangerous of the chlo rinated hydrocarbons used in industry'. *** we have known since the first world waf what its action is on the human body, font was used by both the Germans and the British in airplane slope, and in both coun tries gave rise to cases of acute veilo"' atrophy of the liver; but, ir. spite oi 1 voluminous literature and an impressive number of clinical cases, we fir.d no if stance in which the amount of poison in the air was determined. Therefore, .the-star-da5" ten parts per million, is based on Zang?ef; statement that this solvent belongs '-v:ts> particle size deer till it may reac microns, only one fifth of the perce microns. This is, foundry dust caus chipping, jobs whi the industry know foundries are the more chipping is n If our knowled; required to produc ^ng. this is still t what constitutes d: hons. Here the Pu! mS much valuable jnental investigate: -JlEcJwhttsrrranS" S7 "'`"mg, hive carrie. an<i. in cooperation Governmental Safety Service in Industry 113 "t gf Air 100 50- represent our best :110111cm, but we ad. is oi'tcri based on . truest work. Take ppeu to be engaged ctrachlorcthane. We igerous of the chlo-ed in industry, and the first world war human body, for it Germans and the . and in both court 's of acute ycllo,v but, in spite oE a and an impressive -s, wc find no in* a: poisc.-s-ir. re tore, the standard, based on Zangger's vent hclonc? wiU* aniline Hitd nitrobenzene in the most toxic group- We have little data with regard to the other chlorinated hydrocarbons, except 04, about which we do know somewhat more.' As to the other-, our knowledge comes chiefly from the studies made by pharmacologists wito souglit a relatively non-toxic agent for cases of hookworm in fection winch is not the same thing as in dustrial poisoning from fumes. To pass over to that very controversial field, 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 tree silica that may be permitted in i workshop. This is to be expected. Poison ing from gases and fumes, even if slow, docs not take fifteen years to make itself evident; -silicosis may. Moreover, other factors, aside 'i-.'from the actual proportion of free silica, '> affect the dangerous character of a given t : Must. v,-:"-Take foundry dust, h may be rich in' ff'stlica, running as high as the notoriously ^dangerous granite, yet. while consumption |;khas for centuries been the occupational disA.-iase of stone cutters, this has not been true 1*3of foundry workers. Recent brilliant studies yfof this particular dust, notably the one by Hatch and Moke, have provided an explana tion for the difference between foundry dust and other silicions dusts, for it has been shown the silica content of the former is . chiefly in the large dust particles, and as the particle size decreases, the free silica falls, till it may reach, tor particles under 2 microns, cr.iy one-fifth or even one twentyfifth of the percentage in particles over 10 ( microns. This is, however, not true of the I foundry du't caused by sandblasting and by dipping, jobs which everyone familiar with the industry knows to be dangerous. Steel foundries are the worst, probably because more chipping is needed on steel castings. If our knowledge of the minimum dose required to produce poisoning needs ampli fying, this is still truer of our knowledge of . at constitutes dangerous dust coiicentra!`ns- Here the Public Health Service is do n's much valuable work. Their two monu- ihvs'srigations. of the Vermont gran1 f. tndustry and of Pennsylvania anthracite mming, hat carried us a long way forward, and, m cctreration with, the experts of the Saranac Laboratory, they have found it possible to establish certain fundamental tacts. For instance, the Laboratory is able to state that the percentage of tuberculosis to be expected among workers in an establish ment where 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 in 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 (lie first is at about five million par ticles less than ten microns ill diameter; the second is probably at a level not higher than 100 million. At the National Silicosis Conference held in Washington in 1938, this formula was suggested for determining the maximum permissible concentration of free silica in the air breathed. Multiply the percentage of free silica by the total small particle dust count by impingcr. If the result is under 5 million, (lie 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 of 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 13 million,, too much. This formula cannot lie applied to a dust with less than 5 per cent silica. Both Xcw York and Massachusetts have made fairly recent studies of the foundry industry and of work with granite, such as quarrying and stone cutting, tunnel and foundation excavating. New York recom mends for dust containing less than 10 per cent free silica. 100 million particles; for 10 to 70 per cent. 10 million; for 70 per ecu: and over. 5 million. Foundry dust, averaging 20 per cent free silica, should be kept down to 25 per cent; the dust from abrasive b>a-'t-- cleaning, avcracing 70 per cent down to 10 million. Massachusetts allows 25 million inr foundries, 10 million for granite stone ir.diand 5 million for pure -ilica dust. "M'si i4 )'A?i I >/ irjll: 114 29th National Safety Congress Source of Dust I Percent of Quartz Suggested SiatxSard J (Tree Silica) In Million Particles (Below 10 Micronsjper Cabic Foot of Air, Gold Mines, South (yrica1----- 66 to 95------- -3 to 4.5 million. St Chief S Metal Mines.Broken.Hill.1. Australia--------------------------- 10 to 17-------- 14 The titK been "Dcr no other ; democracy Tunneling. Sydney. Australia------------------------------- 90------------ Cinder G ical fashic State indu ine even-c at one tim Gold Mines.Ontario--J2 nioes]! | oto 35 f- * Jj -------8.5 the role c States an! Iron Mines. Canada --;----------50----------- ! -------- 5 law" to t year aiteT | accidents Granite Cutting.Barrej (Rock,2G5) Vermont I Dust. Average 35 t--9 to 20 - over ar.d c By one mobile ha Metal Mines. Tri-State Area - 90 5 method o: I lawed the it a prist machine, meeting 1 Potteries, West Virginia. 1--20 to 30 10,000 otl ideas and Anthracite Mines. Pennsylvania. (Rock 43% Coal. 6% I Dust 90 % quartz) Ccal.2-4X -----5 tolO Rock Work e-7 dust average 55 Democrat: "Democ dustrlai s. lional pro Subway and Foundation'. Drilling. (New York City | Less than I to64. 10 and error het'ore in: industry ' fit its prt foot the We must not forget that the adoption of any of these standards docs not mean that there will be no silicosis among the work ers. In the South African gold mines, the free silica in the air was brought down to 3 to 4.6 million particles per cubic foot by 1933, but cases have continued to develop, taking 14 years now, on an average as against an earlier average of 9j4 years. In Earre, Vermont, the Public Health Service use the d- great need of careful studies of actual con- | don. etttons under which damage from poisons J ar.d dusts occurs in industry. It is in our | c:untry that these studies must be made. There i of unifor and regui - --.c day is past when we could look to Ger ventions < many as the source of knowledge of indus Governmi trial toxicology.- Now that authoritau'l. j -- - the Amer y.sition has passed to us. And this particu- ) statement ir method of determining safety limits > 's facturcr means of a combination of experts in scv` ciation a iound cases appearing after only ten years trai fields, chemists, ventilation engineer--, at 6-9 million particles and after 9 years, at r.r.d physicians is peculiarly American. 0 all stress need for : 20 million. They have placed the maximum other country has made anything like already < allowable number of particles at 9 to 20 contributions to this branch of industry million, which is certainly not extreme. hygiene that we have. But sve need a E1*3 duirerr.cn: ut what I need not say anything more about the deal more. methods : liavc taken a br :r,tin's mind. s tessarv for me to rry certainly piJ}, accidents. 1 am a* .ny accidents tho* \ce had not take difficulties. But I . job for them b safety program a tins rid oi iho Occupational Disease WEDNESDAY MORNIN'G SESSION October 9, 1940 5-Tile meeting on Occupational Disease, planned as a Panel Discussion, was called to order by the Chairman, Walter S. Paine, Manager, Engineering Department. Aetna Casualty S: Surety Company, Hartford, Conn., who presided. union is almost a civ program. Panel Discussion mlization and sid- * CHAIRMAN PAINE: At every meeting Considered as Industrial Injuries;-" This about the am n. working in veer itc job, he is Dot money and has i '.hibiliucs. His doe* going to have w out." The doctort be $25, $50 or po* ^ j j,ave attended in this Congress some one has raised the question of industrial dislfTo This is a subject whiclt has been -'^aligned in some cases and has been a l'an- ry on the part of others. This, however, gould not in any way destroy the realities are back of the industrial disease prob i going to have a :eks, and there *5' v there. That is i ^Jljt^the rSqre'have discussion asked the of this medical broad problem. profession ami tv* Kthelaw to help us this morning. Each pha-e r^.the problem will be discussed on an or- aring the time be is :vc a defin:te side* .vs he is going cnefit, he is a to ; to go ahead ,ut : and, again, l* a favor ar.d yon * sderly basis. We have assigned as the fir-; speaker for each of these subjects one of the : men on this platform. After he has finished bis preamble, we will ask the members on the floor to present any question they may have bn the subject. physical cendittw- We have the following subjects to he di-- lem do play a H-' cussed: "Health Hazards in Spray Paint- program. : *JS" Dr. Eugene Walsh. Associate Super- y : Ladies and C' 74 4r of Medical Service, International ,-imcnetresesaftttisstirzmaent'Ciroa*no1r^.u* t*, otHabiabj`rje,vvceats-.,ter Companv, Chicago, will open this :;cl that the Chat-" * ^ catigue and Its Relation to Occupational m turn to ^ > ^"se." This subject will be taken up in. e3haH ot yhe P"" 1 Norbert- E---n-z--e--r,. -D.riector of Labora- ,rc gUd ... **> Mount Sinai Hospital, Milwaukee. ot more d:.-cu- . N^Tbe Toxic Limits of Common Solvent- " this P*"?;- } *jls subject will be opened up by Dr. a good pa:- 0 be 'VPlv 1 jn L. Eelknap, of Milwaukee. ,a' industrial Processes." Dr. B-.l. P will also |iancj]e [hij subject. will be handled by H. A. Nelson, Director of Workmen's Compensation Department. Wisconsin Industrial Commission of Mad ison. We all regret that severe illnes- keeps Dr. Paul Brchm, Supervisor of Industrial Hygiene Unit of Wisconsin State Board of Health at Madison, from being present. The panel will be opened on "Health Hazards in Spray Painting." Dr. Walsh. Spray Painting DR. EUGENE WALSH: Painting i- :t topic that has received considerable atten tion. There has been an increasing number of hazards imported into the trade. Mn-t of these have received wide attention, par ticularly in the past few years. It ha- ln-vn incident to the wide use ot the -pray gun and of tiie lacquers, particularly. Many oi the solvents and products used in the paint industry have known toxicides. Others are in tile experimental stage, so far a? u-e and so far a- their hazards to health are con cerned. In the old days of brush or dip or flow painting, -till widely used, solvent- of rather low volatility were employed, and the haz ards associated therewith were not a- great. However, when we come to the spray gun. particularly in its use in the recently devel oped lacquer-, we come into a ho-; -i an *Tnln AffonS." This will he han't'.--'. -olvenl.-. J-- L..r- M. J. Reuter. Dermatologist i ,-Htilolr,gisti of Milwaukee. i.vk !'*ne ja.t , i-T] . t '*wt one ! :jjc mo't !m|*on:.r*. * "Shornd ,,nal Ih-ra-c- 1 The quantities used per year m Ijctpurand solvents in the paint indu.-tr. .: the United Stall- reach a-tronomicn: ii-i-rtionv M.u-.v. mane Me- art- u-cd. 166 29th National Safety Congress In the paints we have the following haz ards : first, the pigments. There has been a growing trend definitely away from 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 of the lacquers in cludes the driers, such as ethyl lactate or cellusolve, monomethyl ethers and various other chemical products of known and un known toxicities. Also, there must he a fiexilizer or a substance giving flow to the plastic. These are relatively high-boiling lowvolatility products, triphenylphosphate, cas tor oil, camphor and others, again of known and unknown toxicity. The toxicities of the various individual products are often known. It is not the toxicity of the pure product, however, that we are often concerned with. It is the prod uct which is used commercially. It is often the impurities in minute quantities that add to the toxicity. For example, we may say there is. in the case of xylol, some question as to its inherent toxicity. However, since benzol is so frequently a contaminant, wc do have <emc benzol toxicity to be consid ered when xylol is used. Also, when have two substances which are used to rzjj, a paint or lacquer fluid, its-toxicity, res^. ing from the combination of the two stances is not usually that of a summit^ of the individual toxicities of the two. Tjj is, if we have two products (A and B), A#- lie viewpoint of the paneL on (his subject, namely he spray painting? EDWARD SMITH (J Malleable Co., Buffalo, N. 'i is made about spraying w one-plus toxicity, if we wish to use dj DR. WALSH: Spraying terminology, and B of one-plus toxicity is a common procedure, d may get a resulting toxicity of three-pi* - largely calcium, it is a rela or something of that nature--just to use* substance. It is irritating tc arbitrary form:------------- jff tree and may be follower The methods of control are: First,4 substitution of non-toxic products suci i we mentioned in getting away from ioi hearing pigments in paints. We are fora to have alert chemists in the paint incaaj who are alive to this problem. They a constantly striving and working with lie* dustrial hygienists and the physicians bid? cough. Not infrequently th hunts in whitewash which products in them but, or cashing is a matter that is ' week, and perhaps a mom! done in most industries day eiposure is relatively infr hazards are not great. veloptng non-toxic products, so far as hoi .Likewise, most of the wl pigments and solvents are concerned eedures are done in large, c Another and is factor that has been con'Idea li..ITfh'jat.t isn't true of some is done in closed tu: roc importance today in places with poor aeration, i toxicity the mechanical dcvelopmctff^ `pr0Cess is to consume the spray fancy, no gun. Many precautions years ago, in itsd were taken. Ttejifl .''time, to have the individi gineers weren't particularly interested bet] 'tome manner. Just a simple A man would spray with one or aaotber. spreading the toxic substances about Today, however, with the development of l mechanical dust vould be usable if -anv length of time. type res the cxp< pressure spray guns, with the devdopoad of engineering methods of control of X-Ray Examina and fumes and dusts incident to the pmssjj DR. ROBERT M. BUF we have less toxicity. . ^jjj V Stale Medical Assn., St. P: If an individual corporation is alert aj there methods by x-ray c: serving and controlling the hazards Fe*f, "time to time or from year very little toxicity need be encounter*; .'W progress of bronchial most processes. This includes, of county- of these paint inhalation precautionary methods for the DfC'WVALSH: There when I speak of the industrial hygiersj/r* .^ould answer your questio the engineer's phase of the problem. "S Ihtt Most roentgenologists, individual is working in a place ginecrir.g methods are not feasible 10'' at the idea of makin. *ohiectasis by x-ray. Th the vapors and toxic product5, theca t*e in the x-ray are lar; dividual must have his respiratory *. vessels and fibrous ; tion tO-.prevent inhalation. Most It is true, however, assinoocgtlrvipoeatninwo,tsnaayntwhdtrhhoeituchhgefhuirmatrehaesectiuriosesnsetpdhiiersaHtwobayrvasey'"wlo'33i--v._"aJAti^.zrrjlit.->:...***<en*..tigPabCaae<lihh--,,^t_T;ubracstPc}--!3aalnnid"ot'sdtheniwnrodhtupnicmrsrOhoteril: I ha ve very briefly outlined son.^:(M:"tiaroetCr,^a`bear'ng paint, major points. Do you choose to P*1 : e>Vve`\ChangCS 01 SI question? CHAIRMAN PAINE: IDiscus: f ^'is ah ' fr the ordir : Assist Abed' s few , he carried on from the floor and 1 V.: e changes in the Occupational Disease 167 used. Also, when v vhich arc used to ^ :id, its toxicity, Tesul' ation of the two that of a summation cities of the two. ThJ( ducts (A and B), a 0f I viewpoint of the panel. May wc proceed this subject, namely health hazards in liaray painting ? ,%eD\VARD SMITH (Jewell Alloy & 'Malleable Co.. Buffalo, N. Y.) : No mention -^Hras made about spraying whitewash. we wish to use thj, &DR- WALSH: Spraying with whitewash t one-plus toxicity, K{ fej-a common procedure. As whitewash is toxicity of' three-pim. calcium, it is a relatively innocuous nature--just to u^ ^ Yfobstance. It is irritating to the respiratory Jttree and may be followed by a chronic rontrol are: N' First, fht Keough. Not infrequently there are contam- toxic products such as ' iffaants in whitewash which may have toxic tting away from leadaints. We are fortunate .s in the paint industry .products in them but, ordinarily, whiteH|.rrashing is a matter that js done today, next %-eek, and perhaps a month hence. It isn't -.is' problem. They arV ^done in most industries day after day. The -.d working with the in- exposure is relatively infrequent and the :d the physicians in de- ^hazards are not great roducts, so far as both ^Likewise. most of the whitewashing pro- :s arc concerned. fcj'ctdures are done in large, open, airy rooms. at has been considered f^tThat isn't true of some tunnels, of course, -nee today in reducing iff it is done in closed rooms, tunnels and thanical development oi '"places with poor aeration, it is advisable, if ny years ago, in its in - the process is to consume any length of ns were taken. The en- .-.time, to have the individual protected in ticularlv interested in it -some manner. Just a simple draft of air or -v with one or another, J.a mechanical dust type respirator prohabiy substances about. Today, would be usable if the exposure is to be of development of lower any length of time. ;. with the development sds of control of vapors X-Ray Examinations - incident to the process DR. ROBERT M. BURN'S (Minnesota rporation is alert in obthe hazards present, .-teed be encountered in ; includes, of course, the ads for the individual. industrial hygienist and e of the problem. If an -.g in a place where en.re not feasible to control :.c products, then the in.- his respiratory protec-halation. Most of tr.t : used have a narcotic ction is hy way of *!> e itsprratory tract. Tats is the way of control- ay outlined some of the ou choose to pursue thi` State Medical Assn., St. Paul, Minn.) : Arc 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 ? DR. WALSH t"There are those that would answer your question in the affirmabve. Most roentgenologists, however, rather .scoff a: the idea of making a diagnosis of bronchiectasis by x-ray. The shadows which we see the x-ray are largely those of the Wood vessels and fibrous structures of the long. I: true, however, if an individual is Using svi-.e paints which bear silica--and pne pa-.r.t that I did not mention is that used ln the porcelain industry, silica-bearing Paint--that is another problem. If you are using a silica-bearing paint, you will get the characteristic changes of silicosis. AIXE: Discussion "'ill the floor and also from However, for the ordinary pigment, so mle ;; absorbed, so few of them produce Proen i.,Vc changes in the lung, they rarely show on tl-.e x-ray. Most of them are stopped by the mechanical aids in the nose and upper respiratory tract, that is the hairs, the cilia on the lining of the respiratorytract and, as such, are coughed up, rather than persisting in the respiratory tract. However, if one is using paints over a long period oi time, it is conceivable that a chronic bronchitis might result. However, here one is on thin ice. There are manyother factors incident to the causation of chronic bronchitis that are equally as, or more, important than the products used in the paints, either the pigments or the sol vents. MR. CARR (Eastman-Kodak Company): In spray painting in rooms, using lead-free gasoline as a solvent, we have noticed as much as 450 parts per million of aromatics, and we find that many lead-free gasolines now sold contain a large proportion of ben zol, xylol and toluol. I wonder if much at tention has been given to that fact? DR. WALSH: That is a problem, it is true. Certain fields of oil, particularly those bearing the naphthionic add oils do, in their cracking processes, result in benzol in con siderable portions, in some instances, in the gasoline. The straight paraffin oils may re sult in some benzol but not so much. It is a factor to be considered. It depends largely upon the amount of benzol present. In some instances it has been said to run as high as 10 per cent in certain gasolines. That is not usually true. There is one factor to be considered in gasolines, ar.d that is the difference between benzol, which is the ring-structure and ben zene, which is a straight hydrocarbon, and relatively innocuous. It has some toxic prop erties, but they are transitory, largely. Benzol has developed a chronic toxicity. This particular subject is receiving attention now, but very- little has been produced to indicate that benzol is a definite toxic agent in the gasolines produced. But if the aro matics were up to about 450 parts per mil lion, you certainly are on the borderline of toxicity. I think it should be reduced, if it is at all possible, by oroinur, 'methods. At---least tlte men should be watched very care fully for blood changes, so far as benzoi exposure is concerned. MR. CARR: In that connection, it has been necessary for us to go to a respira- ill a ;t i-i? iki i.;if5La hjipj ill jl?fWi! KljH . ir' ;. J/:i\-,~ -if-4S y-y.s. jSfefr m=<s m$g& "VkSr,?/" * ggwii >> 8.SS.S :;w; 2 :'; ?'; 16S 29th National Safety Congress tory protection o the supplied air type, sup plied also with a charcoal canister at the man's waist, so that when he breaks the connection temporarily to go back in the room, he still has the protection of the char coal canister. The connection, when broken, automatically shuts off both the air supply and also the air connection, so that he can not breathe the room air. MR. WALSH: That certainly is a fine arrangement. DR. ALICE HAMILTON'" (Division'of' Labor Standards, U. S. Department of Labor, Washington, D. C.): In the Division of Labor Standards in Washington some two or three years ago, when I was visit ing automobile plants, I was told they were making a change in their coatings. I wonder whether that has proved to be true? They told me they were substituting synthetic resins for nitrocellulose and as a solvent diluents used in the lacquers which w.e are> now employing. The process is very muci^ the same. sg \Ve are beginning t, iuspicion. Dr. Gat Company believes it There has been some change in the length^ [tin we have thou of time required to dry these lacquers, butf ' rfj," as the years the constituents are the same as they wertjg : accurate knowledge W. H. KRAUSE (Allis-Chaltners Mf..' perhaps encourage Company, West Allis, Wis.) : There havej ; [jut probably woul been recent changes in regard to the diluents?? tkn. used in paint. Quite a few of the larger companies are now-producing hydrogenatetff- MR. GUMMA R iouId like to offer naphtha. These do contain considerable: Commercial toluol. q,uantit.ies, o. f benzol and toluol. I wo.nder,Kifs'*i ! Joes not contain a,r. there had been any experiments marie with* SquoI regard to the toxicities? IS - CHAIRMAN P. Benzol Frowned Upon pass on to the next Relation to Occupa: DR. WALSH: I should have mentioned;: ject will be opened when we were speaking of toxicities of sold Director of Labors- vents, that the medical profession frowrf pital, Milwaukee. were using hydrogenated petroleum prod upon the use of benzol as a solvent or ucts which had very low volatility. It seemed as if that were going to be a revo lution in coating in automobile factories. I luent in any proportion. We just don't li] "Fatigue and O. benzol, regardless of its percentage, becari_^_ . it is so easy to get out of hand, and tl>?| DR. NORBEKT 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 from no person other than Alice Ham ilton. It anyone in the room can answer the question, I am sure that she can. She beau tifully reviewed the entire literature in a publication that she produced in 1936 called "Recent Changes in the Painter's Trade" which is Bulletin No. 7 of the U. S. De partment of Labor. It is a beautiful presen tation, and it is worth while tor any of you interested in the paint industry to read it. Concerning the question at hand, I know of no particular changes at the moment that have been instituted in the industries that I have been acquainted with. I do know that such things are in progress. As Dr. Ham chronic effects of its poisoning come on.st slowly and so innocuously, they creep uj on you before you know it. It requires ratba close observation wherever there is anj benzol or toluol. srS morning I g. 7 Irrel of activity a Fatigue is a state \ transient character. Understand it and ; So far as the hydrogenated naphthas arg **Out, so far -z concerned, it has been said that the hydfffig that sta genation does not change the chemical st : V>rk which makes lure of the naphtha,- and it does not inert Perform what may particularly, its toxicity. If it is in relative?^ output. large quantities, 400 to 500 parts per then there is the problem of the toxicitir inherent to the hydrogenated naphtha its^ But we would much prefer not to see zol at all. CHAIRMAN' PAINE: Dr. Hamilton, you wish to say anything else on the s jeet ? DR. HAMILTON: I think not. My s<' of the subject is four years old. I ! perhaps very important tilings had lighf -Ince'then. Apparently benzol is 5 lurking danger which arises in all 50f unexpected ways, especially as we us* ^ cracked gasoline than we did before, . Jtiis charactem ? characterized mitigation by c I will elai.iir 'he strictest s ** *n occupation* k direc cssr?in .aj, s ai the a to7tPBt ut adiisease interpret the v, used in t: s`IOn from !,ca r'^3rd an oc. ilton suggests, I think that they arc changes agree that it is something thnt * ^ cheal"' in the right direction, in many instances. avoided. -3 orcum- DR. A. L. BROOKS (Fisher Body Di Wc always advise the subrthut'O^jSj vision, General Motors Corp.) : We do quite toluol, when possible, for benzol, bu* hlch' und a lot of spray painting. I believe there has think any industrial physician won! |( been no radical change in the solvents and ing to edvc a clean bill of health t 'V *-VV oows. Thr pS ' teO - .,'jr Occupational Disease 169 l'h t If; . beginning to look upon it with more cr>' much .- "__e_TM3_c-iLon. |jr Gammon of believes it is much the du Pont more harmful ,1,e lenpi, 'dwrs, bvt l!le>' wert .|: _Ccflipan. thought hitherto. I hope lie pan rdl as< the vears go on, accumulate more knowledge about it so that we may "ers JJig. here have encourage its disuse, also. I think flfat probably would be in the right direc- lie diluents '"sen- larger o3 '-MR- GUMMAR (Barrett Company): I drogenaied onsidenable wonder ii made with -- -ould like to offer one minor observation. ^Commercial toluol, as sold in tills country, ^i-does r.ot contain any measurable amount of [-benzol. 'S?-CHAIRMAN PAINE: We will have to on to the next subject: "Fatigue and Its 'ifkhtion to Occupational Disease." This sub- mentioned, tits oi solon frowns vent or 4-. : don't-like jerl will be opened by Dr. Norbert Enzer, -Director of Laboratories, Mount Sinai Hosl-ji'sil Milwaukee. *j a.V- Fatigue and Occupational Disease ge, because :d, and the ;ome on so ; creep op tires rather '^GDR. NORBERT ENZER: At ten-thirty :vjn the morning I generally have a very low .?fcar! of activity and suffer from fatigue. -'.fFaligue is a state of bodily ill health, of ere is' any '^transient character. It is evanescent, as we 'J abderstand it and as the term is commonly .aphtha! art - the hydro-.mical struc-,ot increase, hi relatively ""Bed but, so far as industry is concerned, d.ffadgue is that state of the individual at "!?brk which makes it impossible for him to perform what may he considered an average rood output. per million, c toxicides litha itselfto see ben- It is characterized by certain symptom'. It n characterized under ideal conditions of mvxstigation by certain objective findings *oich I will elaborate in a moment. nnilton. did m the sab- t. My $tu<h , I though1 ,ad come :ol is still > all sorts O' -. e use mote ore. I should 1* -titution o but I dc ( niki be h to tolu* la the strictest sense of the term, I supVp* an occupational disease is that condition *aich can be directly traced to some agent j* circumstance in employment which can bo labeled as the causative factor of the disnse- But as our horizon widens and our Xc^Pt of disease becomes broader, and as *o interpret the word "disease" as it was 'mginallv used in the Greek sense, a state of ^ation from health, or dis-ease, then we i^7` reard an occupational disease as any f ill healtli which has been contrib!o by circumstances of employment. ^Ende- tha; definition there is hardlv a ."bich, under some imaginable state rs, couldn't be related to what the s doing. Tho'c arc the two extreme definitions of Lite term "occupational dis ease.'' Now, any disease will produce fatigue. It is almost synonymous that disease limits the output or the capacity for work of the in dividual who has been affected. What wc must recognize today is that fatigue may also constitute a state or 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 until 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 rind out what circumstances of employment con tributed to fatigue, to correct those cir cumstances of employment to prevent fa tigue and, hence, to increase the output of the individual in terms of his occupation, without sacrificing any quality of his health. Now, 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 thinkbefore 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 strengtii 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. Now, monotony of work may be the greatest contributor to fatigue. I use that as an illustration. For example, we found out. in one small investigation, that individuals employed at work which called for dexterity and nimbleness and a high degree of mental alertness fatigued in les' than a twenty- 170 29th National Safety Congress four-hour period. In ocher 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. Xow, 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 beej' able to show in some small investigation, ' that if it could be arranged that this job BEN JOHANEK (Conno: \Vakefield, Mich.) : Do you i ,,{ this is caused through imr could be done in the sitting position, the.' DR. ENZER: We are nc output would be increased and the individ- - ^at nutrition plays an imp ual would suffer less fatigue. . fjj nervous fatigue because we k It has been shown that, in jobs which? certain elements in food that call for a to-and-fro movement betweof' [or the integrity of the centra more or less fixed positions, without much?' iera. But we have been able tc opportunity to rest, if the period is broken?, preliminary experiments and f hourly or-at hour'and one-half intervals, ' ys that, in a general way, f, and simple freedom of motion allowed to;- cept in an extreme instance, is get out of the range of what he was doing, - but in acute instances it is. U rest is instituted and fatigue is relieved, '.'re bv that? An individual who We have been able to show that the app|R cation of bathing, in certain kinds of indus-?/ tries, will produce a diminution of fatigue ~ and raise the capacity of the individual to'! prived of food for longer t: mally accustomed, in other meals are separated by too Ic rime, fatigue will be produce that on ourselves. We took resist his industry or his job. Those are': early morning until late at i some of the features of the occupational ` able to show increasing fatigu aspects of disease, or the industrial aspect", of fatigue, rather. With that casual mtrbqj : We were also able to sho duction we can go on and attempt to answer*' well known, of course--that some questions. tain kinds of food which g Tests of Fatigue -sdfsk -v porary relief from fatigue, sugars, carbohydrates, and n: a .'-been done on the proteins of CHAIRMAN PAINE: Are there acy; questions from the floor? This is an intcrj csting subject. DR. WALSH: I should like to asks: question in relation to various tests of fa- 1 tigue. The psychologists have all had peopk, sense that I have tried to 1 this morning, diet is a factor . cause it becomes a disease st . ease state induces fatigue. Di l state of fatigue if we hr. disturbance in the habits of di putting round pegs in square holes and ail that sort of thing, rapidity of processe- . Factor of Noi: That is one method that is not my concept of the way to measure fatigue, but it brins>. up one point; namely, the relation of fahP* . to the mental status of the individual Again, the psychological yardstick ma/ applied. What is the relationship of P? telligcnce quotient of the individual to tigue? Does the person using his min(1 his work fatigue more readily than one . ing physical activity in which no menta fort is .equi.ed ? DR. ENZER: If I may restate the <1^ tion, I think Dr. Walsh really wants ^ MISS MARY LOU SC .veagram & Son, Louisville, "** 10 know the effect of f rtgsrd to fatigue. ** ENZER: Noise is a f. * demonstrated that objee St "c way if a laboratory, i e tested individuals for l . Ir'tf0n rate which, as I : TX base line. Afterwards, w>th a sound of a and rate, the . ,r Whether we could fatigu out whether individuals of low I.Q-, sn speak, experience the same phenomeno^ fatigue under the same circumstances anoilT1"1 ar,d >n that way c molH j.centcr f the brain, . a d,s,ra one center fro individual of high I.Q. 's'. to^-d that this invest DR. WALSH: That is right. DR. ENZER: I would say he ^ though that is not generally rccogn*2 ' ts rat^?r intcrcsti' lx* _ y three, perhaps. 0 . COn?titutionally, Imlivi. t'v : Occupalioiinl Disi'dac 171 qHANEK (Connor Lumber Co., sensitivc to sound, because we could pick. tav? W- '^Lkefivl'd, Midi-) : Do >'ou not think 3 lot out from a group of individuals people `hl* * ltl0n. tit !C 'n<iiVKj. jobs "hicj, n:,n!o. ubtetrwa-'uitrcnt d *? i'fok,, 1 tntervji, allowed t was doinp elicved. '3t !,ie appij" :ds of indus, a of fatigm individual to Those '"'''ff*thhisisi^s caused through improper food? e>JZER: Wc are now recognizing ^"fcat* nutrition apl1a-ivycs nnnn iimmpnonrrttaanntf-' npnarrftr iIn ib-rVouj fatigue because we know there are elements in food that are important the integrity of the central nervous sysvv in But we have been able to show in some Preliminary experiments and from some sur- that, in a general way,-food intake, ex- <:'cepb in an extreme instance, is not important, '7but in acute instances it is. What do I mean 'Vi by that? An individual who has been de- j:'Drived of food for longer titan he is nor.'.ft'razmily a. ccustom.erwd4, *inn Aotthhoeer twuoftrrdnsc, iiff nhiisc ^Steals 2Je separated by too long a period of if.time, fatigue will be produced. We showed vsTjbat on ourselves. We took no food from Nearly morning until late at- night and were whose flicker phenomenon was greatly de pressed when their ears were stimulated; which suggests, perhaps, that such individ uals work best in a quiet atmosphere. That is a speculation. Another type of individual constitutionally wasn't affected at all. His flicker phenom enon was exactly the same rate. The third individual had his flicker phe nomenon raised; in ofher words, he was stimulated by sound. I think casual exam _in_a_t_i_o_n _a_m_o__n^gst ^yo__u_rselves 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 occupational -stria] aspect casual intro. ~pt to answer y*ble"to show increasing fatigue. ^.igWe were also able to show--and this is Bareli known, of course--that there are eer- ?;SV__lpa_oi_nrarkyinrdelieof f"frfoomodfawtighuiceh, give most some temnotably the 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 th^e day--w^e found that 1fa0tiilgBUuSe accentuated the direction of their natural con ' -i"- pf.cAs^.bgeaenrsd,oncearobnohthyedraptreoste,inasndofadgieoto. dBudet aml has the VfV re there any Ajqise that I have tried to lay the subject :s is an inter- -shjliis morning, diet is a factor in fatigue be- mlike to ask a us tests of fa: all had people e holes and all Ir'cinse it becomes a disease state, and a dis- ijrase state induces fatigue. Diet will produce hyTV'state of fatigue if we have some acute tjf'&tnrbance in the habits of diet. -j.lw' ' Factor of Noise ' of processes, lot my concept e. but it brings ction of fatigue the individual, rdstick may be A^MISS MARY LOU SCOTT (Jos. E. i ..Seagram & Son, Louisville, Kv.): I would .Eke to know the effect of factory noise in ...regard to fatigue. .ship of the in.dividual to fa ng his mind in iy than one do- DR. EXZER; Noise is a factor in fatigue. We demonstrated that objectively in a sci entific way in a laboratory, in this manner; We tested individuals for the flicker phe- h no mental ef- nomenon rate which, as I said, constitutes ur base line. Afterwards, we stimulated sS[;ttiututitaionnaall tteennddeennccvy.. iInn ootthheerr wwoorrddss, tthhee 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 oi 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 tbe 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 y. ears ago. Age is an important restate the quesliy wants to find low I.Q., so M phenomenon o! sumstances as an ight. ear with a sound of a`regular'intert-' "factor in that direction. The longer the in- '.aty, rhythm and rate, the object being to dividual is at a fatigue-producing job, ,-.:*e whether we could fatigue one center of sooner or later there will come a time when ... "K brain and in that way effect fatigue in his fatigue becomes manifest. ... .aether center of the brain, or whether we could distract or.e center from the other. We found that this investigation brought We have found that our so-called fatigue testing standards showed no important fac tors, so far as age was concerned; but the light two rather interesting things, or I older individuals had a lower threshold to say he does, al- would say three, perhaps. One is that there the thing that produced the fatigue than the recognized. lr*. constitutionailv, individuals who arc Younger individuals. In other words, it is !7H, iiil Jkwij :i'fl i| i mism .. fit !W Wp'V-' itiiiiji m c- .. .oJwl!**-* , iXV :,r .-if m. - A i -^vf'r/>., 172 29tli National Safety Congress not entirely true that experience with a Job is a guarantee against fatigue. CHAIRMAN PAINE: In order that you may not be fatigued. I am going to change the subject. I am asking Dr. Belknap to take the two next subjects, 3 and 4: "The Toxic Limits of Common Solvents" and "Lead in Industrial Processes," and dwell on those subjects as one. Toxic Limits of Solvents DR. ELSTON L. BELKNAP: Mr. Chairman, I know there may be several dis tinguished guests but I am sure that we in the medical profession always feel peculiarly honored when Dr. Hamilton is in the audi ence. If there has been anyone who has been responsible for bringing to the atten tion 'of American industry and the medical profession the importance of toxicology in industry, I think it is Dr. Hamilton. I will emphasize a few of the toxic limits of the common solvents, so-called thresholds. While these limits have been more or less agreed upon by. authorities in this field, par ticularly such as Doctors Drinker, Haggard and Hamilton, there is no threshold that is arbitrarily perfect, and the actual decision of whether or not the solvent has been toxic is the observation of the patient who has been exposed to that solvent, by a physician who must determine whether or not there has been a temporary intoxication and whether or not there has been a residual. Dr. Walsh has really very ably covered the subject of the hazards of spray paint ing, and solvents which are the chief hazards of spray painting, but I will mention a few which I have grouped in increasing order of toxicity. As an example c: probably the least toxic solvent--I say lea:: toxic because no solvent is not potentially toxic; in fact, some go so far as to say that 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 iubstances such as benzol in 5 to 10 per cent in certain gasolines, cer tainly would alter that safe threshold. vrhc next group of solvents which arc- slightly more toxic, are the amyl ami butyl acetates and ether which arc allowable in -100 parts per miiiion. Some authorities still state that they belong in the 1.000-part-pcr- million ciass.'The most recent report classes " them as 400. The third group of 200 parts "per million, * include the following; Methanol or wood alcohol which, as you know, may have a 1serious effect on vision and cause blindness---^ toluol and xylol, tetracltloretliylene, in--', chlorethvlene and turpentine. anyone in the factory. We profession have always felt put our cards on the table. V is a great deal simpler to foi axiom and tell the truth. 5o for instance, the benzol comp on its barrels, the word "Poi in a position to know whctlu The fourth group, which has dropped to-fcl/ . less did that because they w, 100 parts per million, include carbon tetrjfSJ I know they do it. chloride and etliylene dichloride. '^fij Then the fifth group of 75 parts per milvf; lion, benzene and dichlorbenzene; and finally nitrobenzene, which we, fortunately, acre-`I? ally use very rarely as a solvent, is 5 parts % per miiiion. I think there are many o; that should put the same label ucts. In this connection I wc of a case that I was asked t young boy, in the middle o working in a shop w hich mai I thick it is important to remember that* these solvents, if in sufficient concentration^ may kill. This is in contradiction to tbey other subject that I have been given, which'J denly became very sick, had Ss was dizzy, and had to stop working with a substance wh: as harmless. is lead, which very rarely kills. These soft;: When I first heard of the vents kill, first of all, bv simple surfocationjii! > I would want to see the proc if they are used in an enclosed space, 'suebud x plant and get my inform as in a vat. But the sinister element of lht5j,1 rather than attempt to talk to solvent, of the toxic solvent, is the fact by telephone. (The medical t it affects the central nervous system because,; & whole is learning that it can as you know, these solvents are fat solvent^ty responsibility by demanding and our nervous system is largely made ro\ ff fatty ttiicscstuiAe /ow rr lliinpnoiirdt ttiicscsiulPe, sno the netr'riyvj?TJ ous system is very easily affected. We involvement, therefore, of the eye, one ofrgr the most highly developed nervous struc-rm* tures. Then we have central nervous systems involvement, paralysis, inability to waBgS." Also, we must realize that some of the*v solvents actually damage the liver and thepj kidney, causing an acute Bright's disease. 1^1 is thought that some of them may causjfb cirrhosis of the liver. know all about the exposure that come into their hands.) - When I went into the sho; tills worker was using a larr dipping it into a large bowl o he then slapped on the mo: grease off. On this particub evolved the idea of setting ordinarily, perhaps, blew the from him, directly opposite jaterial and blew the fumes fact Hevgot cooled, and the Fortunately, one of the best solvents one of the most dangerous is not inclinkr.;in the list at all now, the tctrachlorethylfl*?! group used in the airplane industry' tX^J post. That bad the peculiar ability to 3'^^ every part in the body, including the he* ' _ muscle. That, too, is said to be a c0.ntS?r inant ot somV of our other solvents. ^ been mentioned that possibly the . I asked the foreman wha Joaterial,.a__n_d_he saaaiiud hnee dniindnn'tt t was stock material, perfect as he knew. I said, "Well, I konpros*wetwtir'th->a--t'-l* * IS" ' ,llerc 'v into m2 of *' shed routine. We in the yard, fir cor We finally got a flashlight, a: trrel of benzol marked "Pf contnminancc in tricblorethylcne was the reason why trichlorethylene t'-3 innlly had a rather bad name. -5s I think one of the most important to remember in dealing with the coni - Now,-, no one in that shop 1- *ere doing. There were a doz -=ere^oert.iv'0; ^ t),c ?ri,r.e tl. l,ad not gotten tin a good solvent is that v.c arc dealing'' ( potentially dangerous substance an - ^be curious thing about make any effort to conceal that fact ^ was that in another d- m-?.; Oicttptitioim! Pi.u'usi l/.i '- report clas^ rti per niiilion. anol or wood '. may have a ause blindnessrcthylcne, trj{ has dropped to e carbon tetrade. 5 parts per miler.e; and finally rtunatcly, actuvent, is 5 parts remember that : concentration, adiction to the en given, which rills. These sol:ple suffocation, .sed space, such element of the . is the fact that ; system because, are fat solvents, largely made up sue, so the nervfleeted. We have the eye, one o: nervous strutnervous system .bility to wait some of these -,e liver and the ight's disease. 1: item may ca*j;f est solvents ar.f is not included .tracliloretliylene industry' 'n '*7 ability to attach ludine the hexto be a contxm solvents. It ^ ibly the fonr.fr ylcne was restylcne had on?' important th'- e. h the control^' re dealing stance and ^ : that fact tf 'anyone in the factory. We of the medical 'C'rotCssin *'ave alwa)'s ^c,t tfial "c like t0 t our cards on the table. We know that it h? a great deal simpler to follow the ancient 1 vciont and tel! the truth. So that I admire, for instance, the benzol company which puts ' j|S barrels, the word "Poison." I am not . j position to know whether they more O' less did that because they were told to, but A j know they do it. tltink there are many other companies vvlhat should put the same label on their prodl^icts. In this connection I would like to tell .:%{ a case that I was asked to see, where a t --j-oung bov, in the middle of the summer, "working in a shop which made motors, sud''-doily became very sick, had severe headache, -?wis dizzy, and had to stop work. He was ,.*Wking with a substance which he regarded '-frit harmless. gfoWhen I first heard of the case I insisted 'Vl would want to see the process and see the -,j-cplant and get my information firsthand ^rather than attempt to talk to some foreman .jly telephone. (The medical profession as a yvhole is learning that it can only fulfill its ^'responsibility by demanding the right to '{.know all about the exposure of the patients . .that come into their hands.) When 1 went into the shop 1 found that -this worker was using a large paint brush, dipping it into a large bowl of liquid, which fcc then slapped on the motor to get the grease off. On this particular hot day he evolved the idea ot setting a fan, which ordinarily, perhaps, blew the fumes away from him, directly opposite the bowl of , tutorial ar.d blew the fumes directly in his i ..face. He got cooled, and then he got sick. "r * *sked the foreman what was in that ..material, and he said he didn't know exactly; _# was stock material, perfectly safe, as far 'Jjke knew. I said, "Well, I would like to TMw "'Hat it is." So there was considerable "Psetting of routine. We finally went out 1010 a shed in the yard, completely dark; 7s ^ally got a flashlight, and we found a rrel oi benzol marked "Poison." ! S'-"', no one in that shop knew what they doing. There were a dozen other worn7s "oh doing the same thing but who, /^nateiv, had not gotten this brilliant idea cf (t>e fan. ,Th<t curinu thing about this particular *"r'P "a 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 the)1 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 see 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 dean 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 legan to get happy and whistle and sing, and he began to look forward to the experi ence at the end oi every 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 materia! which they had bought from a supply house in another city, and they did r.ot know what was in it. We finally found out it was ethylene di chloride. The course of that individual is interest ing, in that we put him in the hospital. It eventually cost that company quite a lot of money. I was in this to find out all I could learn `about' "the" action o"i that particular substance. I put the man in the hospital three cr four weeks and cid a number of delicate tests on him. Well, he came through, and interestingly v. c found that he had an opportunity to dc- M M 1 ;?lis a >% "Irif h.M' ill -i*i Ilf -.ir 1 - , iAf'O 29`lt Xationai Safely Congress velop a cold once or twice. Every time lie did, he developed jaundice. Then, ot course, we did liver function tests and found reduc tion of that. We found he had a weakening of the heart muscle. We found a definite loss of 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 mcdicin'c 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 see a man who has said, "I have lead poisoning," do not forget he may have some other disa'oil riles and diseases. such as acute appendici'.i ;. gallbladder, kidnev colic and so forth. Jri my private praclice mv intefesfha's been ~M-,arpcmrd so that I always make an effort t : take a very careful occupational history sn a patient, even though he may come to m a purely as a heart rase, lung case or whnt-ha ve-vou. In this particular plant in Milwaukee, which began by having and still has, as a large proportion ot its iv-.rk, storage battery plants, when f came there about tei _\Wri ago wc were having an incidence oi about 24 lead cases per 100 employees per which corresponds pretty well with the f*r.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 departmem and management, we dropped that to an incidence of 2 per 103, and for the past five years we have had no cases of ]ead poisoning at all. Wc arc still handling lead, and we are still handling it in large amounts. I think that in the storage battery indus try. probably, men arc exposed potentially, at least, to the greatest concentration of lead for absorption directly into tiicir bodies this in any other industry. I am giad to report that, having followed this particular group of workers of about SO for this period, it the end of ten years they are certainly just as healthy and, in many respects, I think: healthier than the general run ot the popu-I lotion. Of course, we have reduced their 1 lead absorption, but at times it will break^ down the physical resistance and respiratoiy^ protection. They occasionally have largtj doses of lead. Many of these workers weree persons who had had lead poisoning or seri-^r ous lead absorption in the period of ofci servation. ijf- Lead is one of the most widely used so-_ called poisons in well over 200 Industrie,; I think there is no doubt but in the large' industry the hazard is well controlled. First of all, it is recognized and then every effort is given. N'o expense is spared to study the men and to reduce the continuance of 3-Tf exposure. However, in the small industry,., which is the major portion of industry mthis country, lead is continually cropping and even silicosis, which got the center the stage in recent years, certainly >n y1 j cousin, has now taken a back step, and w has come back into its own, together 'nt the ever increasing use of solvents. I would like to stress again the dang** here is one of non-recognition, that "e 1 our trouble in the small plant, not in large plant. I will rapidly run throng ^ types of industry where I have seen poisoning occur and in winch it is t"1 portent factor. ^ The most important is the storage industry. Then the streamlining or ol,r " j mobiles and trucks where, after course, as r first smooth, jt cooled, grinder and finely divide the fact tha jay lead inc Remember : nore dange very rarely through the ception of i organic and It is rati smaller pla give up ma Here is a r horse-and-b to hand filir ire heavy : The proble by machine It has ah iag was ve perience in it is very ro where lead substances, forth, whic. however, le because it stand the w Here wc finely divi bum off ol the large : either by r ing. There divided du ternember : fectly into eelates thr. 1 make : ?ny workemg o-or ^ Purpc wrker. In the i sf,iPs, of c f'e of le Te*n coat' fo:mis a f niost invis syster do!n5 tha! "Pinion, Occupational Disease 175 11 >ca:t " abou; -r year, ;,'c j*,. Public time. ursc, as many of you know, they were at ?Lt smoothed off by lead paste which, after fcooled, was then ground by machine lender and produced a great amount of . fjv divided, inhalable dust. Tliis brings up Ti act (hat the most important hazard in v lead industry is the point of inhalation. jjynember that load dust inhaled is much more dangerous than swallowed, and that *' Ttrj. rarely are lead compounds absorbed - 'through the skin, perhaps with the one ex' cepdon of tetrachloride fluid which is an -. organic and fat soluble substance. ..i.i ' It is rather amusing that many plants, /-vsmaller plants, particularly, have had to | ..igive UP machine grinding of welded joints, t ,'^jjere is a return of modem industry to the ifcborse-and-buggy stage. They are going back 'tji.jo hand filing where, of course, the particles heavy and are too large to be inhaled. "r,Tke problem can be licked, however, even _|psy machine grinding, if one uses respirators. ,-yVlt has always been said that lead poison- ''*njg was very common in painting. My ex- perience in ordinary painting nowadays is Sights very rare, particularly on inside painting ^here lead has been substituted by other ers .wot V: ; or Seri-.] ri of ob- ' Ayr-;-' .tances, such as titanium, zinc and so iorth, which are harmless. On the outside, - ever, lead is still used, in many instances, .because it is the one substance that will id the weather. used so*; -dustries...; [Here we come again to the question of the largt divided, inhalable dust where men led. First -ry eSort Vyicra off old paint in private homes; not in ^j'tbe arge installations, of course, or sand, tiidy the blether by machine sanding or by hand sand 2 of any s' ' mg. There we have tlie question of finely industry', :V divided dust which is inhaled. You must iustry in .remember that dust when inhaled passes di- ping nr. V. rraly into the system and immediately cir- enter ft .culates throughout the entire body. in Wif ' - I make a recommendation, therefore, that and her wiin dang*' worker that has gotten his lead by burn- 0r sand'nST* be given a respirator for i*: that purpose, even though he is an outside ,y worker. we hs H in ti* ougtr >* cen 'f31' an ^ * yU?0 the wrecking of old buildings and old .f** t course, there is the constant pres- L** 0I" absorption v. hen tile steel has 'form coatec* 'vitii several coats. It ideally 'aoa5-1 *u.me v*'bich is so fine as to be ai- . tjj^ mvisible and is absorbed directly into .. batted system. The oniy way that a worker iur an'*0-. t OpinSionthatst can to really protect himself, in my use an air-i.nc 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 Navyfound 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 Slate of Wisconsin, for a great number of years past, we have had oniy three cases, one of which was really a serious case, and that man was one who rcmeltcd--lie 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 stce! when it is scrapped. Then I would class as the fina! 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-vmeets_reduce lire'exposure to 1.3 milligram', I don't think you wiil have a case of t >; I m & : LY 3 29th Xat'wr.al Safety Caaa lead |*Hemever, as a matter of practical intcrr.-i. I think it is very difficult to vet there in ordinary industry, and I would more or less formulate 3 as a sate level. I think it has also been found by other workers. However, if you pet over 3 you certainly have the possibility of serious lead absorption. 1 want to emphasize that mere kail 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, hut 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 lend 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 man should first of all be responsible to the highest man in authority in the plant, so that lie can po 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 danper, whether there arc volatile solvents or lead, so that the danper to the men may he prevented before it happens. I am not making a plea for absolute sub stitution for and avoidance of the use of lead. I think industry cannot pet 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 rio ill effect ;Yom 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 thernio- staticnllv controlled 0 the temperature of the lead doc- not exceed 300 degrees? DR. BELKNAP; That is a good prsc. tical question. As we know, lead melts at a much lower temperature when volatilized In my experience, lead does not really volatilize until around 1,000 or 1,100 degrees. In this group of workers that I am fob low ing, some years ago, large lead pots, two or three feet in diameter, were unhooded be cause of certain changes in technical pro- ' cedurc, and the plant never got around i0 the hood. T disapproved of that and re- '' pcatcdly 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 hecn 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 y 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 :(f. linotype workers we found no evidence afa lead absorption in some of the shops wheret they had no suction. I would not say in mjf? own experience that hooding is necessary ah 500 degrees. ' MR. CARR: 1 wonder if there is any evidence to indicate the toxic limit for butylg alcohol could he raised above that given We had experience over some twenty yean);' with the same group of men, working UM; concentrations from 200 to -100 parts p*fxf million, ar.d under careful examination theyg; have shown no indication of trouble. -t_ One other question is whether much work,, has been done on toxic limits of dioxene. ^ DR. BELKNAP: I think Dr. Hamilton^ will have to state if she recalls whether wee; have toxic limits established for dioxene. ^ DR. HAMILTON: Dioxene is the trade - name for diethylcnc chloride. No toxic hind has been established for that. We consider ^ it a fairly *ate solvent until some very "is astrous cases occurred in England f[ over-exf*c-ure, causing five deaths- ... then we have looked upon it with a 2^ deal more suspicion. There has not . enough work done on it to establis maximum allowable concentrations. ,* DR. BELKNAP: In regard to bl,th^ cohol, the butyl radical acetate is h'uCKi ^ toxic than ethyl or methyl, particular [ would be interested in your point o [ think probably i: limits. MR. GLMMAR pletely the principle 0f safety' standards should be based on toluene, there have used in the lacqu: painting came into t iir as fine mist, a: orates at a slower inhale the mist, vc Is toxic. I have employers State, New Jersey nho for the past si any reported cases < ing; yet Ohio in i.: had over 69 cases line in the petroleur As to the experi: no experimental dr. should be such a confusion arises i ; tinguish between c `.'ing. It is a fact th V. ceatrations, toiuen `.toxic than benzol; ' chamber where th ; million, you wouk from toluene and with benzene, but : . phenomenon from ing. CHAIRMAN 1 "dl be "Skin All handled by Dr. M. Skin , DR- M. J. REV 0 what extent t! posed to injurk !rnt*nts and the v ** no* surprising t S*?1 are a major `;m*'d States Pu 69 per .^ln diseases " >00.000 worker . J year, that oH rPV'i alTec,ed wit their v, orl"'. spiashes o; a I"ary J" in r*sions. Occupational Disease 177 temperature of I think probably it could be made at safe ' degrees ? Emits- s a good praclead melts at a \IR. GUMMAR: I want to endorse com pletely the principle of maximum clearances iien volatilized. not really volj. 1,100 degrees, ,,[ safety standards in engineering, but they thouid be based on factual data. As regards toluene- there have been enormous quantities that I am f0|. jsfd in the lacquer industry- since spray- -c lead pots, two painting came into use. It is sprayed into the tc unhooded be. 1 technical pro- dr a; fine mist, and even though it evap orates at a slower rate than benzol, if you r got around to inhale the mist, you get severe effects, if it i that and re- is toxic. \vc cases of lead in't hood. Tbev ' : as it was prac-acticablc, and 1 ad nn lead cases 'ability, and we absorption result ave worked there : out of the pot :s ranging usually I have employers in four states, New YorkState. New Jersey, Ohio and Connecticut,who for the past sixteen years have not had iny reported cases of chronic toluene poison ing: yet Ohio in the past sixteen years has had over 69 cases of poisoning from gaso,Hne in the petroleum industry. ~ As to the experimental results, 1 can find no experimental data indicating the toxicity In this group of <1 no evidence of f the shops where uhi not say in my no is necessary at should be such a low value. Some of the 1 contusion arises from the failure to dis tinguish between chronic and acnlc poison"mg. It is a fact that in extremely high con centrations. toluene and xylene arc more toxic than benzol; that is. if you go into n if there is any ic limit for bun! 'ovr that given? tr.e twenty years men. working is o 400 parts per j : chamber where there arc 20,000 parts per million, you would be unconscious quicker from toittcr.c and xylene than yon would with benzene, but that is an entirely separate phenomenon from the slow chronic pnisoning. examination the1 : CHAIRMAN PAINE: The next topic . of trouble. j w;i! he "Skin Affections" and that will he tether much work | handled hv Dr. M. J. Reuter. its of dioxene? \ uk Dr. Hamihca ' Skin Affections ecails whether we d for dioxene. xcr.c is the trade le. Xo toxic limit at. \Vc considerec ::i some very da- England f ro rr. 'e deaths Sie.cr i it with a goo: re has not beer to establish a".' `.irations. . i j card to hmyi a ` ' DR. M. J. REUTER: When we console1 what extent the skin of the worker exposed to injuries, the action of chcniica |r~:ants ar.d the various infectious agents. ls cot surprising that occupational skin di; 'Vss are a major problem in industry. Th Ux:red States Public Health Service e-t: r-:iej 69 per cent or occupational disease "T- skin df.-xtcs'in. They carried out n said: n 100,000 workers and found, in the cottr- J year, that one per cent of these worker '\t:e affected with some skin disease as t 0: ,:-ejr work. This did not includ splashes oi acids and alkali-. and '. particularly. C - -.nary '-c.lsir,-; infectious of "cratches -. 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 unclcanliness of workrooms, of clothes and of per son. Previous skin diseases as, for example, eczema, are. potent factors, because individ uals with eczema react seven times more frequently to external irritants than noneczcmatous individuals. The skin of the young and old is more susceptible to irrita tion and infection than the skin of persons in middle life. Dry skin is more vulnerable to irritants than oily skin. The skin of certain parts of the body is especially sensitive, for instance, that of the eyelids and genitalia. Anything which lowers the normal threshold of resistance of the skin may act as a predisposing factor in the production of dermatitis and of infectious lesions. These factors include bruises, marked sweating and maceration, prolonged ex posure of the skin to water and especially to alkalis and repeated scrubbing of the skin. These agents tend to remove tin: normal protective coats nf the skin, that is the outer lmrny layer, and thus expose the sensitive epidermal cells directly to irritating material. A point fairly recently emphasized is that individuals with common athlete's font arc much more prone to occupational dermatitis nr the hands. Apparently this infection of the feet acts as a sensitizing inctor. The actual causes of occupational derma toses are mechanical, physical and biologic agents and chemical irritants. Mechanical agents produce bruises and lacerations, as well ns friction and pressure resulting in various inflammations anti thickenings of the shin. The physical agents which may produce an occupational dermatosis arc heat and cold, either dry or wet. electricity, tdrmviolet rays, either from the 'nn or artificial, and \-ray s or radium. The biologic agents are the common bac teria. itingi and parasites. For the most part, however, occurnt-.on.d affections of the skin are the -esuit o- con tact with irritants of a b.cinical -,:arc. I t. ;- i WJ1" 17S 29th Suite mi! Safety Congress usuaiiy acids or alkalis producing simpie 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 animat. 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 "skTnV 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 hud very |n|| i occasion to pass on a question of cancer *' the skin arising from alleged contact ju some carcinogenic agent. C. T. DENSMORE (Hoppers Co. $, Paul, Minn.): I would like to hear a'lit|U about the effects of coal tar and creosote oiis in relation to cancer and what-noiand also the inhalation of the creosote *!'pors. ., 0i industry just as dearie flcjental injury. There are var the problem. One. of J, nothing about it and that is \bteen states in the Union arc ^not compensating occupatic *1 ill. Out of the other states which arc compensating jajil diseases, and some of thi josating by schedule. . DR. REUTER: Regarding the develop!!' ment of cancer from coal tar and creosote,-' I have had no experience. We do know that coal tar is the nearest to the skin and does' produce an inflammation about the hair! fciiicles called folliculitis. It is undoubtedly! cue to the plugging of the follicles with the' tar and perhaps some stimulation of if epidermal layers of the skin from the tar " Kow, schedules are usually ^t there are a great many di= m named, but very generally y [iat they leave out the one occu me which causes the most di txample, silicosis is left out of :. of the state laws which .hav therefore, silicosis, which is a mpational disease is r.ot compc: which sets up this inflammatory reaction-' When we go back to the prir around the hair follicles. I think the saraetiv of workmen's compensation, we true with creosote. But, regarding the actual I the compensation fathers didr. development of hypertrophic lesions of l question at the time the compc skin, particularly cancer, I have had no t itrt passed. That was the tin perience. Ether through inadvertence c DR. BELKNAP : As for creosote, I hajv cases, through design, occupatic had no actual cases brought to my atteS-l ::on. As far as I know,' the fumes would EC p r.o more irritating, possibly, than causing53*" irritative cough. I know of no cases, re c: acute chronic bronchitis or other' clnogenic results. '. '] were left out of the laws pret: lot accidental injuries were to Wed. I think that was largely theiather violent split from the h* system and leaving out of c lb* question of negligence. It t fioleit split, but it is surprisin CHAIRMAN PAINE: We will IcavE ef these years occupational disc ar.v other questions to the end of the & "ain uncompensated in so many ?:on and hear Mr. H. A. Nelson, IndusltW; Commission of Wisconsin, on the questioji!. "Should occupational diseases be corisidertw ?. industrial injuries?" When we consider the nature Phonal disease, which is usu: nsidious process, over which t; ld'. the employee, has no cont: Disease Vs. Injury 'If emPlyeri as these told you this morning, hr H. A. NELSON: Mr. Chairman: cuestion which I have been assigned is s|ceptible of treatment in several ways. ran treat it in a highly technical ruibble about the court construction of J*er of control, there seem: padred times more reason u "*10 cannot protect hir. c V e "`ay should be compcn= -rational disease rather than " mjury. vord injury or we can treat it in E; eral way and ask whether occupations ^ rases should be compensated. That is rral crux of the question today. ; , . , ,i,,i thirty it sometimes astonishes me ln. j;g mppose there is no quest, ^eal crux of the matter is to the employer, and the has b-. lhe 50 stated-accrued li tn ln accrual of dosage years after the passage of compensate ^ . ve are Still disputing this <III(SUnjjtia } in disease, and thi at the (Jjseise mav conl hetlicr we shall compensate jr^d i which mav cause disability and whic' ^ j employer has a large fit! A m- Occupational Disease 179 - had very |jt,ie stion of cancer of ;sed contact %vjL'l 'Coppers Co., St. <c to hear a little tar and creosote or and what-not, ; the creosote vt- j oi industry just as clearly as does an accidental injury. There arc various ways of peeling the problem. One, of course, is to Jo nothing about it and that is what about eighteen states in the Union arc doing. They jre not compensating occupational diseases it all. Out of the other states there are a few which are compensating all occupa tional diseases, and some of them are com- , pensating by schedule. ding the develop.. i . Now, schedules are usually designed so .1 tar and creosote. ' tiat there are a great many diseases which . We do know that art named, but very generally you will find the skin and does i that they leave out the one occupational dis- Vn about the hair t . 'rase which causes the most disability. For . It is undoubtedly -.'.example, silicosis is left out of a great many .e follicles with tie : s'oi the state laws which have schedules. stimulation of tie " i.Therefore, silicosis, which is a serious oc- skin from the tar, >Ecopational disease is not compensated. ammatory reaction 'jfrfWhen we go back to the prime principles I think the same is -'of workmen's compensation, we wonder why regarding the actiol N*-the' compensation fathers didn't face the tphic lesions of tie ^question at the time the compensation acts I have had no ywere passed. That was the time to do it. tjTEther through inadvertence or, in some for creosote, I bait ought to my attes;he fumes would te j!y, than causing is of no cases, really, .hitis or other 'cases, through design, occupational diseases were left out of the laws pretty generally, but accidental injuries were to be compen sated. I think that was largely because of the rather violent split from the old common law system and leaving out of consideration the question of negligence. It was a rather violent split, but it is surprising that in all E: We will Usit oi these years occupational diseases still rc- the end of the ste "lam uncompensated in so many states. Kelson, Industrie bn, on the questioot scascs he constdertt When we consider the nature of an occu pational disease, which is usually a slow, "tsidious process, over which the man him- the employee, has no control, but over -:. Injury which the employer, as these physicians h*'e t0'd you this morning, has the entire Mr. Chairman: 11* been assigned is r. several ways, W technical way a-': construction ot '-r' S Power of control, there seems to be one undred times more reason why the emPyee who cannot protect himself in any ossible way should be compensated tor oc^ ,Pational disease rather than for acciden tal lniujty. an treat it in 2 g'-y J her occupational c-_ t -.tiiaicu. That ' ; rat } <r. [:or. * cc" T- I suppose there is no question, but that V4 real crux of the matter is that or exto the cemm;ployer, and that catties beot the <' stated accrued liability. Here 's been an ; ccrua! of dosage '.vhich nnally "rntuates ir disease, and this accrual is ^'-h that the ,1 .sense may coir.c at a uiven ''tier,;. i M v': 1 r'r has employees who have this accrual of dosage, it may be that in periods of depression the expense to him will be rather great for the time being, and that must be met in various ways. Employers are humanitarian. Most of them would like to do these things but they are also in competition with each other, and that means there must be laws and regula tions for the compensating of occupational disease if the job is to be done in a satis factory way. Another reason that is often given is that industrial commissions and accident boards are unable to decide the question of occu pational disease, as to causation, between the process and the final condition which re sults in disability'. I think that is a rather fatuous objection, in view of the develop ment which has been made in medical sci ence within the last tew years. I think those questions arc no more diffi cult to decide than the questions of aggra vation of pre-existing conditions which are clearly under the law, if we may ascribe them to accidents, and also to the obscure conditions which are ascribed to. accidents, and as to which compensation hoards and commissions have to make decision' every day. Can Stamp Out Disease Rut the most glorious thing that has been accomplished by occupational di'Ca'e laws is the fact that employers have become con scious of the fact that they can stamp out occupational disease, i am glad to say that in Wisconsin we have practically stamped out silicosis, that in a few years more it is going to be practically a negligible thing. Dr. Belknap has si-.own you how lead pois oning can be almost entirely eradicated. That is the glorious thing which we have achieved through, the passage of occupa tional disease laws. I want to give a very few figures show; r.'j the drop in 'ijicohi- in the Stale of Wis consin since 1933 to 1939 These figures are the percentage*1 of cant- pensaticn which vverc paid in siiicO'i5 caw* a< compared wit:: the total. In 1933 the I've- nre was 9.4; 193- IS; 1935. 7 9: 2 and .9 per cent. and. in the yea ]Oto_ per cent - figur getting ni-out oil a Ie-.'i 1. 1 thin:-: puhh,- ! jp wi 1 1 .. !M hit; vie v{fa! f ' . Jgpjj? : r'l Czr-t, t. irS?1" ^---^V '-, ; ' i^'a/a..-' iT.'^f v'-'V 'J\:; saaSg-?.*&;*citfrsf $&*&*&**,t&::.F^ r^rc-ov-fczi-A^^.vsb^'-v tgg|3g&qgg^^^aagaKaAtS^^^ If KJ foil sSgS35t:| I r-r ]) ?9//i Xatimiai Safely Coiia'W casc be compensated. The trend is coming on. I believe that industry and society viil be gratified when the problem ha? 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 we go into the general discussion? ADOLF AMRAM (Hamlin & Co.. New York City) : We passed a compensation law in New York State some two or three years ago. Perhaps you recall that first we passed a most illogical law, the all-inclusive act which acted most disastrously not only to in dustry itself but to the workmen. You arc familiar with the history and the recall of that act. I dare say in a number of states it is absolutely right and proper the compen sation act should include silicosis, but it should include silicosis on a schedule basis, as I think is the case in Illinois. MR. NELSON: All states are not as fortunate as some other states. I think we arc showing generally throughout all of the states that the problem can he solved. Protection for Welders CHAIRMAN 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 subj ects. I. S. GREEN (Edgewater Steel Co., Oaktnont, Pa.): I would like to ask to what extent an ordinary welder in a small plant should be protected? Once in a while there will he a hardening material which has poisonous results. .Other times there will be flame cutting of paint on a product which will raise some noxious poison. To what ex tent would a welder or a cutter have to be protected ? CHAIRMAN PAINE: The question is, how arc wc 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. Wal'li to answer that ques-iion. -- DR. WALSH: Within the past couple of years wc hare 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 the clinical point of v'cw. X-rays of the chest were taken. Disability due to sickness over ju, ten-year perioo was calculated and seen fj each individual man. There certainly was nQ marked difference in sickness rates and jn disability rates in the weiders as comparej to the general run of employees working al ^ |:o might A* .bovcry rate from a ijividual "ho happi ptr cent con-gum ' jot me individual I'jtrast tiicrc. their side in the same plant and in the sanit \'ow, when c ;a economic situation. [j^ic solvents, sate When you are considering welders wh0 are cutting painted materials, lead-bearing paints, or who are welding in confined spaces, you have a different problem; bul ior the ordinary welding group, working in a large, airy room, with ordinary precau tions and ventilation, their health is just is good as any other group of workers. If thev are cutting paint or toxic coatings of my kind or lead-bearing steel, or if they ire limits of an md that the probie jved by a blar.ki Ijoblem, but by a jjjlvsis and study ijjtd to the industiny that this can 1 1 jitry realize that j* forms the key ese problems. working in a confined space, then additional DR. BELKNAP: respiratory protection is necessary. Ufy what has aire 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 weld ing, we have r.ot found this to be the case Dr. Enzer and Dr. Sander at Milwaukee have had occasion to examine at postmortem ' tit is when a wc Bterial that has with lead, he, of t pire lead absorpt ibout as quickly a my other way. a few of these individuals who have beenl- It is very simp! wclding for long periods of time in confined.) tors we have aval spaces, usually. They did find there was an?: whenever he is do increase of iron in the lung hut no fibrosivc sse such a respira causing harm. series of cases om Recently, wc also have examined another T sorption was a v group of wel lers, that is a variant of the' pairing some o' welding trace, scarfcrs, in the continuous imoum of lead. production c: steel. These scarfcrs use a long torch and blow out the defects in the billets rather than chiseling them out. This, group also, while it is an infant in the group of welders, apparently have no health haz- ards of any consequence in their trade. h> other words. I think if ordinary precau tions, so far as ventilation and so forth art concerned, we need not he concerned other than if wc are using lead or chromium or some of the toxic materials. | Also, I had oc> dozen cases of op tanks in a la steel tanks had 1 Could not under jetting lead. Th *ith a torch 300 absorbed lead c.\ 1 difficult quesiir matter of bavbne the work is for CHAIRMAN* PAIXE: Or. Enzer | speak for a minute on the subject and then Dr. Belknap, will follow him right up. MR. CARR: have had in work on gaivam DR. ENZER: I want to seize the oppor nilrous fume f tunity to make some comments relative W coated electrode* the generai attitude of this panel discussion- 1 would also It is most Important that in any apPro;l ; `'datively new d to the problem of industrial health we member that a statistical analysis of Sr,oll{ is not a true criterion of the health ot individual. In other words, just like the 5 cleaning of me U:t of a epem. includes prev.o mm W: fiz&v*-': .; / Occupational Disease iickncii over tf,e ia'.ed and seen for e certainly was no mess rates and ia iders as compared piovees 'forking at :it and in the same ring welders who .-rials, lead-bearinr -Iding in confined rent problem; bn; group, working Li : ordinary precaur health is just as if workers. If they :c coatings of any -or if they art tee, then additional necessary, that was rampaa; die development of iungs due to weldtliis to be the case. :dcr at Milwaukee mine at postmortem nls who have been of time in confined : find there was am .ng hut no fibrosis examined anothr - a variant of the in the continuous -c scarfcrs use ! the defects in ti: ,:g them out. Th:s infant in the grout ave no health bas in their trade, iordinary precaan and so forth are c concerned othd or chrninium rr i-. ' : Dr. Er.zer : riiuject and tree inn: rieht up. ;o reice .rhc-oupo" ament' relative ' :i panei discussit : :any appr3' rial r.eaith we ' a:;.-.:;.-;: of gro the health nt ,p who might boast of a 99</3 per cent Vnvery rate from a specific operation, the individual who happened to belong to that li per cent constitutes 100 per cent mortalji'v for the individual. There is a very sharp ; contrast there. ' Vow, when we talk about safe limits of toxic solvents, safe limits of toxic agents, 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 lalysis and study of the individuals ex posed to the industry. I know of no other , -way that this can be done except that in dustry realize that the profession of medi- cut: forms the keystone to the solution of these problems. DR. BELKNAP: I simply wanted to am-yplifv what has already been mentioned, and . that is when a welder or cutter works on Vcaterial that has been painted or coated R'with lead, he, of course, probably will ac'figeire lead absorption in a serious fashion P-about as quickly as, if not quicker than, in fir.y other way. .-f 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 tue such a respirator. In my own particular series of cases one of our cases of lead ab sorption was a welder who had been re pairing some ovens containing a large amount of lead. Also, I had occasion recently to sec half a cozen eases of cutters who were cutting c? tanks in a large chemical plant. These steei tanks had been lined with lead. They aculd not understand why the men were getting lead. They went through the lead "yth a torch 3000 or 4000 degrees and they aosorbed lead exceedingly rapidly. It is not a Cimcult question to solve at all but it is a lV`:ter f having perfect confidence in what work is for and preparing for it. -`R. CARR: 111 connection with welding. ' ;,ave had instances of zinc chills from V on galvanized iron. Wc have also had 1`iiCiuv-- turmrT'bisoning from tile use c: electrodes. . ;'0,1id al-o like to cail attention to a `-ively new r.eveinpment, that of the flame ^ 'iig or metals iieiorc paimma 0! a special oxlYy-ancecett''llene torch. That 'tdcs pret ions fainted metal - as those which simply have mill scale on them. R. J. WOODHOUSE (Continental Cas ualty Company, New York City) : I had a case a short time ago that I was called upon to investigate. The man worked in a small printing plant where he was assumed to have contracted lead poisoning. After mak ing impinger tests which proved negative, an award was given by the commission to the widow in the amount of $13,000. Tiie lead was melted around 650 to 700 degrees and the experts proved that toxic fumes were not liberated. I wonder what yardstick the referees, used to measure those cases, in the face of such expert testimony. MR. SKYRM; I would like to know the relation of hemlock poisoning and poison ivy to skin disease. DR. REUTER: Poison ivy, of course, ithc most common plant that causes derma titis. Hemlock is occasionally the cause. Poison ivy is an intense irritant to iv.ost people's skin. It is a question of wlicihcr in itself it is not an irritant to all pcoplc'skin. We used to think wc knew the c:m-c of poison ivy dermatitis, but more recent work has tended rather to disprove that we do know the actual cause of what it is ia tinplant that produces dermatitis. Apparently it is a waler-soiublc fraction rather than an oil. Its relation to occupational di-case de pends on what the individual is doing. If lie is exposed to it in his occupation, lor ex ample, as a farmer, WPA worker, lumber man or any occupation that keep- an indi vidual out-of-doors, and he contacts poison ivy, it certainly would be an ocaipaiimiai disease. Poison ivy. dermatitis is api to l.e a much more violent dermatitis than that from hemlock. CHAIRMAN PAINE: Mr Gumner, 'ill you repeal your question? P. W. GUMAER: Tiie question u ay v. ha: is the basis of the comparatively low maxi mum concentrator; of toluol in tiie ab-e.nce of any reported occupational eli-ea-e and are there arty experimental data to ar rant such a lew concentration a in n- f .xpcriinental data denis uiih chronic ; o -..n;--.g ami not v. rtf: acute poisoning"- HE Malls .alls? if m t;r hi- yr.L sia&s ' sCvv.- r L-; ,r .! 1*2 29th National So fat v Couorcss DR. BELKNAP: The question is. whether toiuol is realiy as toxic as ! inti mated it might be, being permissible in only 200 parts per million. Is that right, Mr. Gumaer ? MR. GUMAER: Yes. DR. BELKNAP: As tar 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 in the June 1940 issue of the Journal of In dustrial Hygiene and Toxicology. I do not know whether there is any prac tical experimental work backing that up, but inasmuch as toluol and xylol are very cioscly 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 liecn 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. It is founded very largely ntt guess work. The quantity of 1,000 parts per million for gasoline is guess, and so is 200 parts of toluene. We are hoping that \vc shall be able to give more accurate figures presently. The American Standards Association a committee at work in this field, wiih j small subcommittee. We have just finished dealing with two gases and two volatile sol vents, carbon monoxide and benzol and car 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. \Ve 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 do no cases come. Wc could do that with the four I havementioned, but it means, as you see, a great deal of careful study in the iactory and in the physicians' examining room. Bringing' those two together, we can do it with re^ gard to lead; we can do it pretty well with', regard to mercury, and wc have pretty gootL" data with regard to zinc oxide fumes.in , ^ galvanizing iron and brass foundries and2 zinc smelling; but the rest of the substances"1 still arc more or less in the realm of guess-" work. CHAIRMAN PAINE: May I, in yourbehalf 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.. ADJOURNMENT Off- w:- The Panel Discussion cidents was called to o: -an, Julicn H. Harvey tor, The National Co New York Citv, who CHAIR-MAN HARVf to welcome you here th: of introduction, I simply just what the National in mind by the phrase dents." All too frequerr dons of this kind there that we were thinking munity" safety work. Itiinking of safety wor basis, but in another d thinking of a progranvidual industry or cor the problem of accident employees during the 1; away from work. This inception some seven i following several sun d'at a very great pre dents occurred to crop!kit the job, as compr. occurred while they f recall one illustrate J well known nation;. nany thousands o f em Jood job of safety wo ~,le ^at fact, during of their employees i at work, but during th "tor empl0yees had b '^tleblew/- , e lound that situa: wflnCes- Proceeding odustry is cIoser t0t rSan,zations can bei . Tem- t0 d a gOOf ., ST"'?} it miglr cnnl*8' 3 special Pro I^P'oyees and do son trs safety bevond 'a1 Ouurr program thi 10 take "P certain r'trtf-Tr 10 tins ventilating current be interrupted tor a period ui 24 hours and with the same amount of methane being liberated, there would be 5.760.000 cu. it. of explosive mix ture. Should this be contained in an entry 10 ft. square, the length of the entry mould 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 specified percentage between .5 per cent and 3 per cent, it will operate -pccial electrical circuits through suitable relays in cut off the power in a section or give warnings in other parts oi the mine Cr to the outside. Methane recorders tor COr linuously indicating and recording methane in main returns particularly have been p^. tectcd recently and are designed to be locatcd in tan 'houses or other convenmiei at places. There is no relation between the volun* ui methane given ott in a coal mine and the chemical composition of tile coal, as boti bituminous and anthracite mines product methane, and methane has been found n metal and other mines when tunneling through carbonaceous shales. The comma occurrence and explosibility of methane am responsible tor numerous mine disasters aai every precaution should be taken to keep a within sate limits. This can best be done by the iim: and guidance oi methane detre- tors. <r Pulmonary Diseases in the Mining Industry By DR. R. R. SAYERS Table 1.-- ftvpatioiis c.\ Siliceous dus .Vonsiliccous i<neral popuiz ids were foi no anthracite In the study fines and thi Sr.er, Okla.,* ssis or tuber, song men wh ids, pleurisy, Director, United States Bureau oi f 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 by irritating gases carry with them the risk of bronchitis. According to Collis,1 it cannot be 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 nr Table 2.--Co. recurrent invalidity and incapacity. Mortafc trts for Bron itv records compiled by Collis' indicate Groups i: that it is of a chronic traumatic origin asso- ciatcd with irritating atmospheric condi ll miners'. .. tions, r..a..t..h..e..r....t.h.--an -of -a-n---i-n--f-e-c--t-i-o-u--s----o-r-i-g-in.i.V-.Tsl jW undergrou Statistics for bronchitis for the general population and for workers exposed to dusts in Great Britain' for 1921-23 show the role played by dusts in the increased incidence of the disease in certain industries. ^Tbc Hewers and g jhles in same < " occupied am htio of rate fo krsto rate for comparative mortality per thousand US* 26 to 65) for those in occupations to siliceous dust was 214, for those expose* 1's three < to nonsiliceous dust 59.5, and for the 8*" oral population 49.6. (See Table 1.) T'ble 3--Infl: lit this connection it is interesting 10 ^ *niong Bi the mortality statistics per thousand October 26 to 65) for coal miners of cunt." , ,, Wales (in which most of the coal nun ^ anthracite) compared with those W ^ Period ~ other groups in England and let, figures for coal miners are-112 fo^ f~r ~ - derground workers and 139 for be" ^ j ^ 8esl getters compared with 46 for ma es ^ j same social class and 50 for all occupi retired males. (See Table 2.) ^ In a study by the United Spates Health Service' 35 cases of chrom Minimj Section 531 ;i,c - for yj j.--Mortality per 1,000 from Bronchitis in Dusty Occupations and in the Ti General Population, by Age Groups ? be& ten 1 >0 be t - Ages nt Denth Compa rat i \ o Mortality Figure 20-- 25-- 35-- 45-- 55-- 20--65 ; 'nine saj <vbunations exposed to cal, as boti :s Produt, found b aSiliceous dust ........................ Vjionsiliceous oust.................. General population................... 1.1 ' o.i 1.0 1 \.i 13.7 4.9 5.4 44.6 12.8 13.3 153.7 41.8 28.8 214.0 59.5 49.6 luaaelitj coorsto :';'-thant art -.5^1 . masters lr.,| ' to Veep ij -`it be iiirt V-snt deter. ^ilii were found among 344 employees of anthracite mining companies examined, rfo the study conducted by the Bureau of yEnts and the Public Health Service at picher, Okla.,* the highest incidence of siligju or tuberculosis, or both, was found eiong men who reported having had bron-'Sitis, pleurisy, and asthma, Influenza and Pneumonia Figures of mortality available for 4,700 miners insured in the group department of the Metropolitan Life Insurance Company' show that in the last quarter of 1918 during the influenza epidemic 64 of these miner; died of influenza or pneumonia. This i; equivalent to an annual death rate of 0 it per 1,000. Among all occupied males aged 15 years and over, the rate from influenza- pneumonia in the same 3 months was 22 per causes rauci :tv. Mortal* is! indicate .Table 2.--Comparative Mortality Figes_for Bronchitis per 1,000 of Certain Groups in England and Wales origin asso-. eric coidi-i Jflal miners1.................................... Bronchitis us origin *AI1 underground workers.......... 112 the gc.tnl ' ^Hewers and getters.................... 139 =ed to dusts j\v tie role :d ir.cidencr stries. Tie lilies in same social class............ V!occupied and retired males.. . "tio of rate for hewers and getters to rate for same social class. 46 50 302 .-.ar.d (ten ns expo*-1 'tn three coun::es in Wales. c enjoiri :r the &?* - l.) Tibie 3--Influenza-Pneumonia Mortal- :ir.g to r.ctc sand '*ount!fi ei "7 among Bituminous Coal Miners-- October to December 1918 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 of bituminous coal miners at ages 16 to 70 in Indiana, Missouri, and Wyoming com pared with 19 per cent among both farmers and "all other males" at these ages in the same counties. (See Table 4.) In 1918, the year of the great epidemic, influenza and pneumonia deaths constituted 55 per cent of total mortality exclusive of accidents among the bituminous miners in contrast with 27 per cent among the farmers and 34 per cent among all other males. These percentages were not as high as the figures for Wilkes-Earre. The fact that thc soft-coal counties under consideration are largely rural areas may have made some difference. 1 i car* n d over. In the epidemic year 1920, the proportion of deaths from influenza and pneumonia was smaller than in 19IS, but. as was'found tor the anthracite miners, the bituminou'vroup showed a wider difference in the pro- lfeife;:u str, ten!<|!?W * Y* \ ;i ; i S_t;| trifijiij! p;'!1'1 Pk-ijb*M' H? mmJSjir hmm mW':? m n - -* n j iK'-Vrl' pkKI: n-M' .4M' -.ipR Ste'U-U '"/: i! 7t?*V;x .; -\y 29th Xainnal Safctv Congress Table 4.--Percentage of Deaths from Influenza and Pneumonia (After Deduction rjble 5.- -M Accidents) Among Bituminous Coal Miners Compared with Farmers, and VV;^ Other Males in the Same Areas of Several Soft-Coal Producing States' uaie groups L.nacr Comparison | 16-70 16-30 - Apes 31-40 41-50 51-60 61-70 bituminous coai miners............... .-! 31.1 49.4 44.7 25.1 19.7 10 4 Farmers........................................... ..i 18.7 3S.4 32.4 19.7 12.4 log All other males............................... . .i 18.6 30.0 29.0 16.0 11.3 10.8 1 The death n-enrdi for soft-coal miners were obtained from 15 cnal-prnducinc counties of Indiana. 1916. 20. inclusive. S coal counties of Missouri. 1917-21, inclusive, and thr 6 principal cual-producing counties ,.f Wvnminc. 1919*25. inclusive. The record for farmers and for "all oilier males' was obtained from the above-mentionrd coal-mininc counties, and'al.so from 5 agricultural counties of Wyoming. 1919-25. pupations ei Siliceous dus y'onsiliceou; ikneral popui. portion of death? from this cause compared with "ail other males" than in 191S. The percentages in 1920 were 29 for the softcoal miner; and 10 for "all other males." gaged in pursuits other than coal mining ia Wilkes-Barre and. vicinity. The percentage of deaths from influenza and pneumonia for these two groups by ages for the yean Occupations e: Siliceous du: Monsiliceous ikneral popui. In this epidemic the bituminous miners at mentioned was 19.3 for anthracite minen ages go to 60 suffered heavy excess mor compared with 13.3 ior males in other b- tality from influenza-pneumonia, but the . (lustrics. (Fee Table 6.) (lifTcrcmial mortality was not finite so great as at ages 16 to 30. Tuberculosis ibout twice, a -g aid for ages : Among hewers and getters of soft coal in England and Wales, the death rate from in fluenza and pneumonia, 1921-23, was about 12 per cent greater than among males of comparable social status (social class 3). The difference was found to he 5.8 times the probable error oi the difference which is certainly a significant variation.- Thus, an abnormal mortality from influenza and pneumonia is consistently indicated among mincr-t of coal--both anthracite and bitu minous--in Engiand 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 Collis' as 134.3, 76.0, and S3.3, re spectively; similar figures for influenza were 47.1. 49.6. and 36.5, respectivelv. (See Table 5.) In 1925 Collis1 said that for coal minen the rate fou: generally the tuberculosis rate apparently!!' low although miners at the coal face sulfa' lie highest r: tuberculosis o-. from the disease ers underground Results of more more than other coal min--! and workers above ground recent investigations seen.' tn (men whr loading or rcc u 3 years). to contradict losis does not the assumption that tubeitti-' occur among coal miners. An' Vhich rork, more t'. 37 per Investigation by the Welsh School of Med jolmonary tui icine, reported in 1937.' indicates that this supposed exemption of coal miners from tuberculosis may be due to a mis- or partial tompietciy cits tn, which rile: d tubercuiosi diagnosis. This investigation revealed a high hr pulmonar; incidence oi tuhercuicsis (35 per cent if ould appear "probable1' cases are included) among the "elsh Xaticn pncumoconiotics of the South Wales coal fate that i' fields and supports the theory that coal dust tuberculosis o modifies the tuberculosis, leading to failure to recognize the disease or to the mistake0 t* incorrect "it the aiiov diagnosis of `'bronchitis." According to Brundage,* an outstanding feature of the statistics of death for hardcoal miners in the United States is their Studies by the United States PuH'j Health Service'* revealed that 6 per cent hard-coal miners examined had clime ^ Tble 6.--Pv Miners ar extraordinary mortality irom influenza and pneumonia not only during influenza epi pulmonary tubercuicsis. The average pre^ alcnce in the adult male population oaff th demics hut at other times as well. In a~ United States is about 2 per cent. The P-c' study bv the Public Health Service at alcnce of pulmonary tuberculosis ante-* Wilkes-Barre, Pa., in 1915-23 and 1906-25* hard-coal mining employees at ages belo* it tu- found that influenza and pneumonia were responsible for 40 per cent of the total deaths compared with 25. per cent among 35 was slightly less than that found throuy; --. studies among male adults in the I Ufaracite r population. In the age group 35 to 44, no>^ ^ fa jn o(^- males at ages 15 to 05 who had been en ever, the prevalence of tuberculosis * i/. V^t -r 4;.V.`A' rk?'^ - . ?r if* ** Mining Section After DedUcti rmers, and Ing States' 14 bl 5.--Mortality per 1,000 from Pneumonia and Influenza in Dusty Occupations 1 and in the General Population 51-60 61-70 19.7 ioT 12.4 10.8 11.3 10.S ui maiana, I9ie. .-producing countio .r obtained (tom -online. 1919-23. (pupations exposed to Siliceous dust............. Konsiliceous dust.... General population. . . . han coal mining b The percenuft and pneumonia fer res for the yean anthracite mines males in other in- Occupations exposed to - Siliceous dust............ .t Nonsiiiceous dust General population. . .. Ages at Death Comparative Mortality Figure 120- V- 35- 45- 55- 20-65 3.3 14.4 30.6 47.2 38.7 9.6 13.7 2S.7 23.9 4.3 11.5 19.6 24.2 25.7 134.5 76.0 S5..i Influenza 1.1 7.7 11.3 S.7 18.3 .5.4 4.8 13.7 HI.6 14.9 2.0 5.2 /./ 12.0 47.1 49.6 36.3 at for coal mintn rate apparently is the coal face suer :hnn other coal mis- rktrrs above groead investigations seen .plion that tuberoiong coal miners A: '-h School of Medindicates that this coal miners free to a mis- or partis; non revealed a h.\rv (33 per cent i: t riuded) among ih; South Wales era ;cory that coal drr leading to failure or to the mistake about twice, at ages 45 to 54 about 5 times, ind for ages aliove 55 it was about 10 times the rate found in the general population. (The highest prevalence of clinical pulmonary tuberculosis occurred among the rock work ers (men who had been employed in rock -foading or rock extraction for more than 2 .*.3 years). After 20 years' service, of .which more than 2 or 3 years were in rock work, 37 per cent presented evidence of pulmonary tuberculosis. In a group of 133 completely disabled former anthracite work ers, which did not include any known cases of tuberculosis, 10 per cent proved positive for pulmonary tuberculosis. These findings would appear to corroborate those of the Welsh Xational School of Medicine that in state that the supposed exemption from tuberculosis oi coal miners is erroneous due 10 incorrect diagnosis. There is evidence that the above increased incidence of til bcrculosis 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 death rate from pulmonary tuberculosis. The mortality rate for tuberculosis for Jas per County was 200.8 per iOO.OOO for i911 and 1912 and 229.7 for 1913. according to statistics of the State Board of Health." On the other hand, according to the Jasper Comm AntmtLerculosis Society, during the calendar year 1912 there were 720 deaths among miner- who had worked 2 years or more underground in Jasper County. Not ail ted States PuM- ; that 6 per cent c' uined had cl-.aai lable 6.--Percentage of Deaths from Influenza and Pneumonia among Anthracite Miners and among Males in Occupations Other Thar. Mining in Wilkes-Barre The average r^' and Vicinity e population o: t`; per cent. The rrtv tuberculosis a vees at ages b<:J' j that found throve 1 -rcieus I hitler C omonrison halts in the grr.rr; j \]nV,ar.Jcite miners . rc-up 35 to 44. hr-' - es in other mtiu; ' tnbcreiilosn Tv" ! ! 15-64 39. S 25.3 15-24 45.2 25 7 67. 46. 33*44 42.9 31.0 45-54 51. S 10 8 - ._rV.-. *.!- t .- 5.5 4 29lh .Wiiional Sii/Yir Congress i Table 7.--Mortality per 1,000 from Pulmonary Tuberculosis in Dusty Occupations Table 8.--Pre and in the General Population Ages at Death Occupations exposed to Siliceous dust.................. Nonsiliceous dust........... {`general population............ _>u- J.VO 13.6 20. ft of these 720 deaths occurred in that coumv hut they had contracted the disease there and some of them had moved away. Of 93 miners in the Joplin District examined by Lanza in 1914," 64 showed definite symp toms of pulmonary disease and 39 of the 64 had the classical symptoms of pulmonary tuberculosis. In a study by the Bureau of Mines and the Public Health Service" in Butte, Mom., during 1916 to 1920 the death records of the State Board of Health were examined. These showed that during 1915, 122, during 1916, 126, and during 1917, 169 Butte miners died of tuberculosis. The significance of the death from tuberculosis of 169 miners in 1917 is indicated by comparison with the rec ords of other regions. In 1917 approxi mately 14,000 men were employed under ground in Butte mines; with 169 Heaths irom tuberculosis for the year, the rate per 100,000 was 1,207. The tuberculosis death rate of Michigan for the 10-ycar period 1910 to 1920 was 97.4 per 100,000; hence the tuberculosis death rate of Butte miners was nearly 13 times as great as that of Mich igan. The part played by dust, especially dust containing silica, in the production of pul monary tuberculosis is shown clearly by figures for Great Britain for 1921-23.' The death rate per 1,000 tor ages 20 to 65 was 592.2 for those exposed to siliceous dust, 172.4 for those exposed to nonsiliceous dust, and 163.5 for the general population; for ages 35 to 44 the figures were 141.0, 46.1, ami 43.6, respectively; ior ages 45-54 the figures were 211.6, 56.4, and 39.0. respec tively; and for ages 55 and over die figures were 150.6, 29.9, and 22.7, respective!!. fSec Table 7.) According to Collin' the prevalence of bronchitis, pneumonia, anil luhcrculri-i- i- 25- 63.4 26.3 37.6 ! 35- ! 141.0 1 46.1 | 43.6 I +5' 211.6 j 56.4 j 39.0 55* 130.6 29.9 22.7 20-65 592.2 172.4 163.3 Outdoor and ind. indoor industries Coal trade.......... Alcohol trade. . . Heat and fumes. Dust of 1. Animal orig high among those exposed to silica dust but 2. V egetable h materials. . 3. Silica......... the incidence of these diseases is not always the same under other conditions such as exposure to other dusts, heat and fumes, or working indoors. (See Table 8.) . rantlcr of instar tion 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 silicons adostries also si occurred among the coal miners of South_ Prater physical it Wales; two-thirds of the deaths and dis-'.. ithecontrol grot: case occurred in the Swansea Division; and;; ' Moderate or ma 39 per cent of the medical certificates-, from any cause w.- granted in the Swansea Division related lo d* control group anthracite collieries." itptlar miners, an In the United States the chronic disease & rock workers. among miners due to breathing air contain There was a ma ing dust generated in the various processes involved in the mining and preparation o< Sirmerts with inc anthracite is called anthracosilicosis. This u .rotrs of emplovrr a descriptive title for the form of pneumo ^cy is manif coniosis commonly called miners' asthma The disease was found in about 23 per cm of 2,711 employees of three anthracite min ing companies studied by the United - *~rs disability oi '"itb pulmonary ir * disability due la ? the occu Public Health Service in 1933. Abo?* *se!ves accordir. per cent of those havbig anthracoMhcnf I'ferat as folic showed evidence of disability, compare! l fti-ular miners: less than 10 per cent in the control S'?.. than 100 n Moderate and marked degrees of disa^i ^ r'11' '*>t of air; handicapped aproximately 21 Pr c' except rock wc those with anthracosilicosis comparc( ^ ^e Pathology of less than 2 per cent of the men ser\i <y'd :n these case control-. t f coal dust in Wide difference# were found in tent of physical impairment 1 'e 0i occupational groups. The highest ^ disability from all causes cotnbinV| ^ extensive fib - U ar. 11h associ. pJj,,:ve changes, ^duii.i. found in the group of men that hat 1 excess mort more than 5 years before the date J *** as a whole i: animation from very dusty to relati' . ^ j k. hard-coal mine dil'ty occupations in the industry ** ir-ade by the . mi -mu Miniiu/ Section Dusty up,u# . ' g__Prevalence of Bronchitis. Pneumonia and Tuberculosis Under Certain 1*?}.. Conditions of Exposure Exposure Bronchitis Pneumonia Tuberculosis 55- 20-65 "wIT 172.1 163J -sed to silica dost bet S?doof and indoor life.............................................. iladoor industries.......................................................... fol trade .................................................................. [tUcohol trade................................................................ ' jleatand fumes............................................................ i-:Oust of .. S)?-:.Aninial origin..................................................... hs j- Vegetable husks and debris, certain inorganic: r^-.materials Silica low low high moderate high low high high low low high high high low medium high low high low high low low low high iiseases is not a]-^, r conditions such u =. heat and fumes,* Table 8.1 . . timber of instances the change in occupa- The anthracite miners' proportionate mortal probably was made on account of ity from all respiratory diseases was about SIUCOS1S -:j'- -Svsical condition. Miners at the coal face, :^v>lrfJJ ---Jc workers, and men who had had appre- S7 per cent 'of .the^ ble exposure to harmful dusts in other _ritain due to silicoa ; iistries also showed evidence of much :oal miners of-Soetlr greater physical impairment than was found the deaths and dis- j Satie control group. wansca Division; and .-; >Jfoderate or marked physical impairment medical certificata ! 'Sim any cause was found in 1.7 per cent of -a Division related to Tie control group, in 9.9 per cent of the rjigular miners, and among 12.6 per cent of l'/i times that of the other adult males in the same region. When proportionate mor 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 38.2 per cent among males in the same social class. The proportion among hewers and getters of anthracite therefore was 1.4 times that of men of the same social status. the chronic di'mt welt workers. mcathing air contain-' ] 'There was a marked tendency toward in :hc various procesio crease in the proportion having physical im - and preparation or pairments with increase in the number of iracosiiico-i.-. This is Jtars of employment in anthracite. This 'he form c: pneuoro- tendency is manifested whether one con Icd miner;' asthma siders disability of any kind, disability in m ahoui 25 per cm *hich pulmonary infection was contributory, hree anthracite min ,r disability due largely to tuberculosis. In by the United State case the occupational groups arrayed in lb.';-. About U wmselves according to extent of physical ng nmiirnrosilico*' roility, compared uin rlic central group degrees o disability -!y 21 cr cent cl rosis cm a red "id- the nte: serving wpairtr.ent as follows: (1) Rock workers; ") regular miners: (3) all others exposed 10 more than 100 million dust particles per Gmic foot of air; and (4) men in haulnge- n>'s except rock workers. The pathology of anthracosilicosis as ob- ^'ed in these cases is essentially a deposi- n of coal dust in the lungs, accompanied the iS\ ::e severi' c 1::C ;; rale c> cvrr.-*-*-tCJ :ii ilia: vi chan-1* ,:c -e oi <v ;y in r extensive fibrosis. both diffuse and "duiar. w;ih associated functional and de- ",cra;:ve changes, (silicosis modified bv dust i. ,,Tht eexxcetc-ss; rr.ortniitv iron re-piratory '"'eases a; a who I is ex; enence-: y Arncr- Cwi; hard-cr.t: es .... ac, miners is clear the Public He:. :rom the we Silicosis There arc various definitions of silicosis hut all agree that the cause of the disease is the inhalation of silica or quam dust." Silicosis is a wcll-rccogniicd clinical and pathological entity at least as characteristic as that of any cause of death kr.awn to epidemiologists." The definition of silicosis, adopted at the International Silicosis Con ference in 1930 and reaffirmed at the 1939 Conference and generally accepted is; "Silicosis is a pathological condition of the lungs due to inhalation of silicon diox ide. It can he produced experimentally in animais." The first investigation of silicosis thc mining industry in the United States was made in 1914-15 by the .Federal .Eureau of Mines in cooperation with the Unity; States Public Health Service in the Jopur. (Mo.) mining district.11 As oniy a few mc-r. were examined at that time, it was >! -cided to exaur. a larger number to gam. .idea of the prevalence of mm. one O e miners of t:11< rli;;r:'\ 5? I :. it fin .'H. fits ' ; A ;,2 'Miiij ! IliijS #! r-Hi .. ; d;i. UA t tJHSKf 5I L N O _ , -M ii " 25 55- 20-65 29ti; Xational Safety Congress 11.3 18.3 rs --- rsi -- so *r 20 -r to o' C'i t-** r20 Cb r-- X. C'I o -- --c rvi" *o -r t: u 7 .7 May 13 to December 31, 1915. 720 mintr, were examined: 45.7 per cent had silicosis and tuberculosis and 5.3 per cent had tu. berculosis.'.1 A later report (1917) of this same investigation by Lanza and Childs' included the results of the first detailed X-ray studies of silicosis made in the United States. Investigations of mining conditions by Harrington and Lanza" in Eutte, Mont., in 1921, revealed that 42.4 per cent of 1,0|J miners examined showed definite signs of lung damage due to dust. From July 1, 1927, to June 30, 1932, the Metropolitan Life Insurance Co., the TriState Zinc & Lead Ore Producers Associa tion, and the Federal Bureau of Mines op-' crated a cooperative clinic at Picher, Okla* to demonstrate to industry a workable method for diagnosis of silicosis, to educate '. workers in preventive measures, and to serve as a model to industries presenting i . dust hazard. Of 27,553 individuals exam-A ined during this period 5,366 had silicosis,'! 742 silicosis plus tuberculosis, and 320 un;T complicated tuberculosis. The chief cause of disability in silicosis is; tubercle infection. The silicotic lung appears to be a more favorable medium for the growth of the tubercle bacillus than the normal lung, not because it is fibrotic, nor because its lymphatic drainage is interfered with, but because it contains silica." Ap- . parcntly silica dust possesses this character istic of increasing the liability to pulmonary tuberculosis. That this is true is indicated by the statistics quoted in this paper which indicate also that silica dust increases the liability to other respiratory diseases. (See Table 9.) .;>5 The results of virtually all studies are if agreement regarding the high mortality ra*e* from tuberculosis for industries in win large numbers of men arc exposed to silica hazard. These rates are so high 1 they leave r.o room for doubt of the .caU;1'r(i and-cfTcct relationship between the and the high mortality." Joint studies made by the Actuarial cicty of America and the Assocta 10 Life Insurance Medical Directors re' that there were 65 deaths where 6 '\f num. pected (about 11 times the cxPe[5 her) from tuberculosis in 1925-193 ^ 0[ a group ot underground miners, idiom v teredo; expected the expc ;nd eigl jmong t covering times a; , ad and An an Saranac ot 5,009 halation dust sl-.rv luberculc of reactii of miner in appro first stag second st third star Prevent The da as the gr mortality need in dust as l silicosis, preventin far as pi centration the work; properties Pacitv to compositi' tmosphe: Particle si Althour breath u- ated by a higher nnsiliccc ttal Pope ^at, in rr Proportio: Wartz, i; tfce finer "tough c "',l defe: . Tl;c Pr :"nction `ih'Oe rdk:iu:insSt t 1 4a cntr0; S'w Mining Section 537 jcr 31, 1915, 720 niintrs '.7 per cent had siHCOsis r.d 5.3 per cent had ta. r report (1917) of this by Lanza and Childs* ;s of the first detailed iicosis made in the United ,|,on1 were employed in metal mines. TuJjrcutosis deaths were fourteen times the ^peeled among copper miners, nine times [ht expected among gold and silver miners, d eieht and a half times the expected jjiiong iron miners. In an earlier study1" covering the years 1915-1926, there were 18 times as many deaths as expected among 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 worker; in certain industries or in connec tion with certain operations within an in dustry. The physician attempts to determine and zinc miners. the extent of the injury to the health of : mining conditions. bv anza11 in Butte, Mont, i ,t 42.4 per cent of 1,01S showed definite signs oi > dust. 127, to June 30, 1932, the Insurance Co, the Tri- i Ore Producers Associatral Bureau of Mines opre clinic at Picher, Okla,* to industry a workable osis of silicosis, to educate entive measures, and to to industries presenting a : 27,553 individuals examperiod 5,366 had silicosis, An analysis by the field division of the Saranac Laboratory"1 of the roentgenograms of 5,000 white miners exposed to the in halation of harmful concentration of silica just 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 in approximately one-fourth of those with first stage silicosis, one-half of those in the second stage, and 65 per cent of those in the 'third stage." `Prevention of Dust Diseases in Mining y-c.. i .The data given in this paper point to dust 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 dt-vi.-e 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. : tuberculosis, and 320 un- is the greatest contributor to the excessive -culosis. -inortalicy from pulmonary diseases experi mented in the mining industry and to silica e of disability in silicosis is dust as the immediate cause of the disease -.. The silicotic lung appears silicosis. Therefore, the principal method of `avorablc medium for the preventing these diseases is to eliminate as tubercle bacillus than the' far a? possible or reduce to harmless con- because it is fibrotig nor centrauen the dust in the breathing zone of :atic drainage is interfered the workers. Experience has shown that the : it contains silica.1' Ap- properties of a dust that determine its cast possesses this character- Paoty to produce injurious ciTccts are its ; the liability to pulmonary tomposttton. the quantity suspended in the .t this is true is indicated atmospnere breathed bv the worker, and its yjoted in this paper Particle size. t silica dust increases the Allowable Concentrations of Dust in Mining Investigations conducted over a period of years show that exposure to certain ennrentrations of harmful dusts for a certain time causes varying degrees of respirator)- dis ability hut that below these concentrations disabling pulmonary diseases do not occur .within a working lifetime. The classical ex ample or this is the experience in Smith Africa with the reduction in mortality from -silicosis that has followed the reduction in air dustiness in the mines of that country. respiratory diseases. (-tt Although any dust may be harmful to hreatb under certain conditions, as indi- virtually all studies are ling the high mortality rWj s for industries in if men are exposed 'jL, ..cse rates arc so high iin for doubt of the insliip between the ha!" -:ality.= 1 Co- ttade bv the Actuary- - . a and the Associat'd; Qted by the data presented here that show 1 "`g-.er incidence of pulmonary diseases in "onsikceous dusty industries than in the gen3* Ptpuiation, physiological studies reveal 2l' ""- mining the harmfulttess of a dust is "Porttenal to its content of free silica or ^ rl2- ^ particles small enough to enter owu--'er !l,aces 01 ,`-'c lungs, and in high s- concentration to overcome the nord"Arses of the respiratory system The - ledical Directors" re'1 ,5 deaths where 6 were * j Hrk:r. ,h,, cv!ic.;ted r.-a* 1 .-eH,. eulisis in 1925-1''-* wrgroumj mine.' i-lO't 01 the pr.ysician and the engineer, together to determine the extent of -iracd -,-t l-.-.dustry tv,! methods for The reduction in the incidence of silicosis in the South African mines attests the ef fectiveness of the control measures em ployed and the practicability of using a defi nite dust concentration as a guide in setting allow able 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 193233 was 9.39 per 1.000 compared with 21.9? ..iii 19ir,,15. (See Table-10.) The incidence rates for silicosis uncom plicated by active tuberculosis among South African miners in 1936-1937 was between 8 and 9 -cr 1.000 per annum.11 The liability among the whole body o: miner- to con tract c di'ease in 1936-37 was less hv 65 : r i -? i M iBl ill, vijp 4R -1 -4 m?y s: i ;r:r\- . [!i< lifi I iSsri;; $i MW fifth'5 j: iheI |S=:X:i:! m:n 0:^\i 29lh Wititiiuil Csnarcss Table 10.--Average Number of Miners Examined Annually and Production Ratts Ti^e for Silicosis in Each Triennial Period Since 1917-18 j yjscd Period Average Number of Miners Examined Annually Production Rate of Siiicosis per 1.00(1 Period Average Number of M iners Examined Annually Production Rate of Silicosis per 1.000 I'll 7-211 1920-25 1<p.*-2o 14,070 13.260 12.523 1 1 MS 19.IP 53.28 pur cunt 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 hv 87 per cent than the similar liability among all miners working for an equal period in 192023. These "new Rand miners" constituted 77 per cent of all working miners examined. The group of pre-1916 miners, who in 193536 constituted less than 17 per cent of the total number of working miners contributed nearly 78 per cent of the new cases of sili cosis. In the study by the Public Health Serv ice'" of anthracosilicosis among hard coal miners silicosis was not found in a control group of mining employees whose dust ex posure averaged less than S 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 anthracosilicosis when the duration of employment was less than IS years, regardless of the amount of dust in the air. Among men exposed 15 to 24 years to dust containing less than 5 per cent free silica, 14 per cent of those who had worked where the average dust count was 100 to 199 million particles per cubic foot, 29 per cent of thoje_exposed to 200 to 299 million, particles, and 58 per cent of the men who had worked for this period in more than 300 million particles per cubic foot, devel oped anthracosilicosis. 1926-29 1929-32 W2-,*5 14.624 16.774 20,159 21.11 13.87 0.59 Among men employed for more than 23 years in dust containing less than 5 per cot free silica, the proportion of persons found with anthracosilicosis under different con centrations of dust was as follows: 5 to 99 million particles, 7 per cent; 100 to 199 mil lion particles, 54 per cent; 200 to 299 million particles, 71 per cent; 300 or more million particles per cubic foot, 89 per cent. 0-9. .Number o: Number o: j'ercent wi 10-24: Number ot Number or Percent w: 25-49: Number or Number oi Percent wi it) and over: Number o: Number oi Percent wi 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 among'persons who had been exposed for more than: 2 or 3 years to dust of which about 35 per cent was free silica, varied from 10 per cent among those who had worked in concentra tions of less than 200 million particles per cubic foot for less than 15 years, to 92 per cent among those who had been employed tor more than 25 years in dust concentra tions exceeding 300 million particles P*r 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 of determining safe limits of dust exposure im dicatcd that employment in an atmcspfierw containing less than 50 million dust par 1 ^ per cubic foot would produce a neShS' number of cases of anthracosilicosis ^ the quartz content of the dust was 5 per cent. In the gangways where t c content of the dust was about ,i'erji|:0n a -nt'c limit appeared to he 10 to l-1 I particles per eration for r it 5 to 10 m: air. Similar Public Healt pneomoconio workers. (S' The relath tration and c cer.tage of >. coniosis was forked in a million parti l'f, 9 per < 1'oars, 20 per 15 years, an those w ho w !'on of 25 m Pneumoconic '5 pears, ar. ^ose who h eentration of cent had 17 Per cent r. Tl,e data c ,rar|cs. anth: fl"uiacturc. ft" treated :,(:|dcd simji rr-ttlts. -. t':' 3<- JCt'on Rate, Mininr/ Section ,|e it.--Pneumoconiosis Cases Occurring Among 798 Workers Exposed to xTxed Dust, Classified by Average Dust Concentration, Length of Employment. Production Rate of Silicosis Per 1,000 Average Dust Concentration (Million Particles per Cubic Foot) 0-4.9 Years in Industrv 5-9.9 10-14.9 15-19.9 20 and Over 21.11 13.87 9.39 more than 25 than 5 per cos persons iouni different conallows: 5 to 99 100 to 199 m30 to 299 million >r more million cr cent. 0-9: . . dumber of pneumoconiosis cases. Number of workers exposed.......... Percent with pneumoconiosis........ -10-24: .. Number of pneumoconiosis cases. v Number of workers exposed.......... 1 Percent with pneumoconiosis........ 25-19: .. N'umher of pneumoconiosis cases. ; Number of workers exposed.. Percent with pneumoconiosis. 50 and over: Number of pneumoconiosis cases. '" Number of workers exposed.. ^Percent with pneumoconiosis. M :ncrs, their help:t 25 per cent oi erground devda working period s group was aartz content ot W) ' (particles per cubic foot. The limit of tol.'eration for rock workers was set tentatively "*at 5 to 10 million particles per cubic foot oi 'yah. Similar results were obtained by the ; Public Health Service in an investigation of osilicosis amon? d for more this ch about 33 prr rom 10 per ces :d in concentra>n particles per years, to 92 per been employed dust concentrtn particles P 1 years oi whio ' pneomoconiosis among mica and permatite workers. (See Table 11.) The relation of the average dust concen tration and duration of exposure to the per centage of workers found to have pneumo coniosis was as follows: Of those who had worked in an average concentration of 50 million particle? of dust per cubic foot of **r> 9 per cent had pneumoconiosis in 5 I'pra, 20 per cent in 10 years, 50 per cent in 13 years, and 66 per cent in 20 years. Oi dtose who worked in an average concenira- iav a minor n* icosiUcos:S- the purpose o' ust exposure & an atmospoo; on dust pari^'; uce a re*!*.cosiheosrs :-t was les = _^ "n of 25 million particles 10 per cent had Pneumoconiosis in 10 years, 27 per cent in 9Pears, and 33 per cent in 20 years. Of nose who had worked in an average con^entration of 10 million particles of dust. 7 jCf cent had pneumoconiosis in 13 venr; and Per cent in 20 years. (See Fie. i.) ^a!a obtained in other studiesTsTausty L cs' anthracite mining, asbestos textile aCt':rc' 'ln^ '"e RolterS industry rave ; |, 'mated in a similar fashion ami have similar, although usually less r'-eu-s-n.t; The -0citjr,n nf tht* thri--' o!,| 0 Si 0 123 0% 0 43 0% 0 45 0% 0 56 0% 0 940% 0 450% 4 404.1% 0 %29 0 0 66 0% 3 301.17c 5 25 20.0^ 0 13 0% 2 29 6.07,; 3 2111.3% 4 SO8.0% 0 8 oc; 4 23 17.4-; 6 3I3S..VC 4 6 66.7 r,l value below which no cases were found and the magnitude of the trends between per cent affected and both time and intensity of ex posure varies in different sets of data, de pending, to a large extent, on the chemical nature of the dust to which workers were exposed and possibly on the regularity of employment. It is tempting to seek to summarize the data oi 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 lie advisable to set up any mathematical treatment because, of all tlie men wiio entered the industry, oaiy :hc survivors have been studied. There :s no adequate way of finding out uhether or "ot men who dropped out of the imiustr;. -..ere in a better or worse state of health a: 'ar as silicosis is concerned than men who T'. mained ill the industry, and thn- there no way of introducing a correction for th:- "Mient -viectioii into a e-nmemati'-s! in -ij.'-M 1 f':: fj ...M " / life .v V * rm 540 29th .\atiunai Safely Cnnarcss Shovelers men). Shoi clers Drillers' h Trackmen Roof trim Figure l,--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 that 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 occu pations, the number of persons in each, and the various activities and time devoted to each acti-. ity in any one occupation. 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 ajrjs ajso a .means of checking thc"efficiency of any control meas ures that may be adopted. Several devices arc available for collect ing and counting dust samples. The im- pinger, however, is the instrument used most frequently in the United States. The Bureau of Mines and the Public Health Service have issued publications describing the method of sampling dust by the impinger (as well as by other methods) and pro cedures for counting and identifying the particles.'*' B Dust sampling is complicated by tiie fact that air dustiness fluctuates rapidly from moment to moment. A single dust count rep resents only the amount oi dust in the at mosphere at the time and place oi sampling and gives no indication o: the average ex posure of the worker over a period of years., especially if he lias not worked continuously at one job. The ultimate lung injury that lie may suffer will depend upon the inte grated effect of the dust over a long period.TM 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 dun exposure of the worker can be calculated. . . ?T Drilling.--Experience m South with new methods of sampling have rc'<t`\.|. that more dust is produced by rnck t`" than had 1 sibling cm leered bv t of control the preset, by the fact remained higher ami those who the excess has been it: of time spe Until re! for blastin: dust or air other than operated au dust, hut ss mining pou more cssent producers especially tr jackhammer compressed . in coal or ii Bhsling.-- dence oE silk [he early pet 'it South A: f the rockdust but to I lasting, and varying amo duced by hi a Hasting then quantities oi lions of whi, d;e mine air -v ventilation Bhnvrling ^Ala.. study,' 'Hatiottship i ress Mininy Section Table 12.--Period Worked at Face by First-Stage Silicotics 541 Average Number Average Number Joh Number of Job Number of of Years Men of Vears Men Shovelers' helpers (bruno Machinemen (drillers). .. 11.4 348 men).................................. 6.8 s Powdermen........................ 11.5 24 Shovelers................................ 8.4 428 Shovel bosses..................... 15.8 21 Drillers' helpers (dummies) 8.4 79 Ground bosses................... 19.0 54 Trackmen............................. 9.8 52 . Roof trimmers...................... 11.3 26 ' nd duration of dust exposure oconiosis. Based on data pre- vcvcr, is the instrument used most in the United States. The Bureau and the Public Health Service etl publications describing the sampling dust by the impinger - liv other methods) and pror counting and identifying the pling is complicated by'the fact istincss fluctuates rapidly from moment. A single dust count rep' the amount of dust in the at- the time and place of sampling no indication of the average exkc worker over a period of n ears, he lias not worked continuously The ultimate lung injury' 'bat .tier will depend upon the in'e:: of the dust over a long period; measure of dust exposure recturc of the variations in dustibest procedure is to determine ss during different stages of an nd. with the aid of a time study. ". the worker's day according to cm in each step; from these da*a : dust exposure of tfie worker can --Exn .'tt'.CU ce in South A trie". of sampling have res calcs i -;:'' than had been suspected, the difference con sisting entirely of dust too fine to be dctected 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 tchigher among machine drillers than among rthose 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 hand- operated auger drill produces very little fine dust, hut with the extension of merhanized mining power drills are becoming more ami more essential and some of them are heavy producers of finely divided dust; this i- especially true of reciprocating drills <u" the jackhammer type drilling dry and using rotnpressed air in the clearing of holes cither "> coal or in roof or floor material. Blasting.--The exceptionally heavy inci dence of silicosis among rock drill miners in he early period of the gold-mining industry ui South Africa1' was due tn the exposure f the rock-drill miner not only to drilling dust but to high concentrations of dust from blasting, and frcriucnrly to the inhalation of drying amount- of the irritant fume- pro duced hy blasting, owing to the methods of blasting in-w.-e:-Rlns-rm-.: produces large luantitios of scry fine dust, the finest frac|ons of which tend to remain su-pended in l!e nune air for a lone time, unie-- removed vein-la; ,,,. Marking--f n the Picher. j . ' -;::ds." it was .litpeuh tn -how the 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 shovelers' helpers, shovelers, 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 shovelers' helpers and shovelers than for machincmcn if length of time re quired to produce first-stage silirosis is a criterion. It is noted from tabic 13 that the average number of years worked by shovclers' helpers and shovelers was 6.S and 8.4 'ears, respectively, while that for machinemen was 11.4 years. Loading and I lavUnit.--Under some con ditions hand loading of coal throws into the air of the working place considerable quan tities of dust, but the amount is about onctenth that caused by some types of mechan ical loading. The greatly increased occur rence of dust from mechanical loading is (Inc not only to the stirring of the du-t 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/0 Poorly constructed nr poorly maintained pit cars or over-topping of coal in cars al lows fall off or fine material to sift through to the track? to be ground under the wheelof roiling eouipment or the liooi- of mules and then he thrown into the air by -peed- s2 2Vth Xuiiouai Xuicly Congress \i Where conveyors {either the shaker or belt type) arc used they form potential sources of dust clouds at the points where the coal is dropped or thrown which occurs `,5) dusts, in ccal mines the order ot in, portance woeid probably be (!) movement (2) gases, (3) dusts, (4) relative liumiditv' and (5) temperature." I tin. dr.-:- .-led v.'t: -r,n"-' of the high ."jifd to the drill ior it; 10 'he back end oi t: 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 culling.--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, shearing occupies an intermediate position, The matter ot movement of air from thf surface, through the working faces 0r places, and then back to the surface is by all means the most important consideration fn 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 or 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 'hea the operating ihrc Rowing position, and Ira,- the hole being drilled, gaping is atfectcd by .jrongli the drill steel; trough the driil steel ini greases. Mining officia concluded that such air probably facilitating retr. Jf (he cuttings from the sble ior entrapping fine it into the air during ^gently they have devote< teigwing drills that pe practical air leakage tlirgui have established reg 0i such drills. Canada i tork along this line, : jate that such drills arc luce about cne-fourtb : don of corresponding `dustless-hcau" features.5 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. keep air dustiness within safe limits if used with care and judgment in collaring wet, using plenty of clean, dirt-free water, and keeping the drills in good repair with ade quate regulation of the proportion of waterand 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 The results oi this st trators can reduce dust silting from drilling ter flow through the increasing water pressur liter tubes of larger ir. -Tests also have bee: 8ureau of Mines" on spraying wa:cr along the steel compared with th: drilling practice. The tc Methods of Control was 0 to 3 gallons per minute, and that for drifters from 0 to 1.02 gallons per minute. ing water along the outs should not take the p The principal measures for controlling The rate of decrease for stoper drills was drilling. However, i a dust in mining operations are ventilation, greater for water flows from 0 to 1.3 gal hy which the device nt: wet methods, proper blasting practice, the lons per minute than for higher water flows. use of personal respiratory protection, and The rate of decrease for drifter drills was of any inclination, it r tituable accessory to rc physical examination. similar to that for stoper drills at cor collaring and drilling t Ventilation.--The more or less generallyaccepted conclusion that coal miners suffer less from miners' consumption than metal responding water flows and rather constant for water flows' of 0 to 1.02 gal'-ns per minute. hole. Tests show that of dust is thrown into t Place in drilling the fir miners, who either die early in life or are The results of this study shows that . Wet drilling standard incapacitated in middle age, is due almost entirely to the superior working conditions in coal mines as a result chiefly of ventila tion. water flow through the drills was increase the dust concentrations in the air decreased, but they do not show whether the decrease was caused directly by the increased water ft Mew York State fc fhsses of rock. The re in Class II rock (t llati 10 per cent fret Approximately in order of their impor tance", the-main features that affect air in metal mines are (1) movement, (2) tempera flow, by some condition influenced by van* tion in water flow, or by a combination o these factors. lreas, which include ti 'Wtilation, are quoted l , b ''Wet driltirtg'"5tia ture, (3) relative humidity, (4) gases, and In most pneumatic rock drills air pas-e I application of wati Mining Section 543 the order oi be (1) movement, relative humidity, jflfc gj, the drill steel with the water. OrdiiSfly' some of the high-pressure air sup- to the drill for its operation escapes the back end of the drill steel, even fiben the operating throttle is not in the "t of air from the .^Sowing position, and travels up to the face corking iaces or .e surface is by all tt consideration ic tion of mines and id forwarding and efficiency of the adequate quantities 0 the places where . requirements o( iemands of safety fy ,f,e hole being drilled. The amount of air 'esapin? is affected by the water flow ; through the drill steel; as the water flow -'through the drill steel increases the air flow 'decreases. Mining officials in South Africa '{cncluded that such air leakage, although probably facilitating removal by the water iof the cuttings from the hole, was respon se for entrapping fine dust and blowing jt into the air during drilling." Consc- Iqnently they have devoted much attention to the most effective 'deigning drills that permit the minimum ough under some practical air leakage through the drill steel 1 to wet methods, md have established regulations on the use applied effectively, at such drills. Canada is also doing much a. the air or its con- work along this line,, and recent reports ted as to render it ; state that such drills are practical and pro- . duct about one-fourth the dust concentra -y drilling is the -.g, wet drilling will tion of corresponding drills without the "dustless-head" features." safe limits if used . The results of this study show that op in collaring wet erators can reduce dust concentrations re rt-tree water, and taking from drilling by increasing the i repair with ade- I. rater flow through the drill steel, either by oportion ct water . increasing water pressure or by the use of g through the drill rater tubes of larger inside diameter. f Miner the du.t uring actual drill flow through the flows for s toper? rtute, anc that for ttilons per minute stoper crtlii "'* rom 0 to 1-3 gogher water flows drifter drills er drills - cord rather consum' 1.02 gallons W ly shov-'i /\ IIS \\*3r tr.e air de-tre^ *r.cr tr.c oc*,vJ ; increased **;*, fl.ucnccd by a coma.r.af.C" Tests also have been conducted bv the Bureau oi Mines" on the effectiveness of 'praying water along the outside of the drill steel compared with that of standard wetdrilling practice. The tests show that spray"g water along the outside of the drill steel 'hould not take the place of regular wet drolling. However, if a method is developed d' "hirli the device mav be used on holes oi any inclination, it might prove to be a 'Suable accessory to regular wet drilling in rollaring and drilling the first 2 feet of a 4e. Tests show that the greatest amount dust is thrown into the air of a working ,,iCe in drilling the first 2.feet of a hcle." : '\t! <truling standards have been adopted V -eiv York State for drilling in various 0, rock. The requirements for drill Cla-s II rock (rock containing more 10 per cent free silical in confined 'which include the use of mechanical -U-ation. are quoted below." ^ et drilling shall mean the rnu'inu*r'P!u'r,-ion of water through tin- cimra! 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 or starting the drill hole. The valve in the water line shall be of such design that it has only two fixed positions, namely, closed and completely 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 clean 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 bynatural 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 pi-ton bore, 3") minimum rate of water flow through drill steel, 0.73 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 througi; 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 he in creased if found upon tests by the Industr-.a! Commissioner that the dust concentration is not in accordance with the requirements of tiie Code. 3. "Drifter-mounted and wagon-mourned drills (maximum piston bore. 4") minimum rate of general ventilation per drill in the drilling area, as shown in the table 'Limita tions in ,-\ir and Water Flow Througi; Sictl.' * 4. "In the case oi positive-pressure .;:liiniion. the air must he well distributed ..v,-r tiu drilling ami mu<i nm create drafts ?44 29th Xalional 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 zone of the drill operators is maintained at a level below that required in Rule 33-2.3 and the appa ratus is otherwise acceptable to the Indus trial Commissioner. 7. "The above rates of ventilation shall he increased whenever necessary to reduce dust concentration to the amount permitted hy 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'4 show settling rate of dust aftpr 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 50 million particles per cubic foot. 2. The atmosphere was bratticed off until '26 minutes after blasting when the ^ratticc was raised and natural ventilation (which was virtually negligible except for eddy currents was allowed to dilute . the dustladen air. It required 2 hours and 20 min utes after blasting for the dust concentra tion to drop from approximately 5.000 mil lion particles per cubic foot to 50 million particles per cubic foot, and 2 hours and 50 minutes to drop to 15 million particles per cubic fcot. 3. The atmosphere was bratticed off until 37 minutes after blasting, when the brattice was raised and 10-inch canvas tubing in. stalled 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 for the dust concentration to drop to 50 million particles per cubic foot, and 70 min utes 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 825 million particles per cubic foot to 50 million and to 15 million particles per cubic foot under the three dif ferent conditions: Time, in minutes, to drop from 825,000,000 Ventilating particles per cubic foot Condition No ventilation............ 121 181 Natural ventilation.. . 105 135 Mechanical ventilation 20 24 In addition, the place (walls, floor, roof or top, and timbers) should be wetted thoroughly before blasting is done, and a water blast should be used (luring 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 or otherwise aids in diluting or eliminating harmful or poisonous gases that follow blasting and that usually cling to the blasted material. Tests" on the effectiveness of a spray of water mist in reducing the concentration of dust in the air after blasting and during mucking of the blasted material "ere ducted in three headings in medium hard hard rock. The use of the spray apparen made it possible to reduce the concentra ^ of dust generated and thrown into.4 during blasting more than 99 per ccn^ ^ the amount present when the spray " . tt-ed. Dust dissemination during nllj' (ore of material sprayed several hours mucking was begun was much es j,]y during shoveling of material t,orcynj; sprinkled just before and during 111 u;e0I. and, of course, the dust present 3`ler ' cither the spray or the sprinkling m In ilosiv' -.lasted .ill l aid i joi.-on iielho .educe of ?anectio: itemn: now a the cv ind r. ind a' ns ri race i lust alir. It :o inv know r. iarmf: Atm; (me ,r *nuld US g; iave I kave I ions lely harm:: 'nee, `taring In (V, artho' `tlCtfj onpur fast i , siing The ^iii ;-*ha Pr. ^<ut >Jkr K Hir >o: 'tarn Minim/ St'diiin 545 jc4S ihail it the mucking had been done ployed to reduce the dust hazard. If work ers exposed to dust are examined period In geneTM1- tllt; lart'er <he tiuar.nt.v of cx, ,-,-r used. the more finclv divided the fid material. the more Itcaviiv the air be impregnated with dust and smoke, j,,d the greater ill be the quantity of isonous gases left at the [dace: hence, ically increased incidence of respiratory disease can be discovered and measures taken to reduce the amount oi dust in the air or remove any affected workers to a less hazardous environment. _ In South Africa all white applicants for Methods should be used that will tend to underground work arc examined and certi --jttee the quantity of explosives used and fied to be physically fit and free of any dis j gases and dust produced. In this Con ease of the respiratory organs and then re xion it will be found that the use of examined every 6 montits to determine and stemming or of some types of blasting plugs report all cases of simple silicosis, tubercu now available will confine more definitely losis with silicosis, and simple tuberculosis Ihe explosive, hence, increase its efficiency that may have developed. In this way com jnd reduce the quantity of explosive used parable records can be obtained for measur anil also reduce the amount of poisonous ing the degree of ptytutnoconiosis and the pj produced and possibly reduce the vio extent of impairment of working capacity lence of the blast and its tendency to raise among employees from wear to year. Com Just and disseminate it into the surrounding parable records will nor be obtained unless jir. It would be well for users of explosives periodic examinations arc. conducted in a ta investigate types of explosives that are standardized way. preferably by a permanent known to give off minimum quantities of medical hoard composed oi physicians spe (armful gases on detonation and to u>e cially trained and having adequate experi them; also, the discontinuance of tlie use of ence in the diagnosis of pulmonary diseases. fuse and the substitution of electric blasting vould aid in reducing the amount of poison Summary ous gases from blasting. Explosives that have been held in storage too long or that kite been stored under unfavorable condi tions as to moisture, temperature, etc., are Holy to give oft", maximum quantities of 1. The principal pulmonary diseases to which the miner is subject are bronchitis, influenza and pneumonia, pulmonary tuber culosis, nnthracosilicosis, and silicosis. harmful gases, if they detonate at all; hence, utmost care should he taken in the goring of explosives to see that they are mt held too long before being used. 2. Statistics indicate that much higher morbidity and death rates trout pulmonary diseases are experienced in dusty than in nondusty industries, especial:;/ where silica . /Vr.voutt/ respire.',.r pr.'.v.gum. -- This dust is used or produced. method of control of air riusttnvss is unsat isfactory in underground mining except for temporary u>e in emergencies Although lust respirators give adequate protection j lI*inst dust, they afford the wearer essen"illy no protection against :cx:c or asphyxanng gases, and are too cumbersome and wcomtortahle for constant wear. 3. Investigations by the Public Health Service reveal that hard-coal miners suffer a high mortality rate iron-, influenza and pneumonia not only during influenza epi demics but at other limes as well. In 191523 and 1906-25 influenza and pneumonia were responsible for 40 per cent oi the total deaths among hard-coal miners compared The Bureau of Mines has established a with 25 per cent among tnait; at ages 15 to xheduie of minimum requirements for 65 who were engaged in pursuits other than -echanica! respirators, one tyre of which is jr protection agamy, dust generated by dis- I -'rgration as in drilling ar.d blasting, 'bout 30 re-piraters h.v evn approved >his schedule. coal mining. Six per cen: of hard-coal miners had pulmonary tuberculosis com pared with 2 per cent in t.nc aduit male population of the United States. The rate for metal miners is still higher. -.'.though _ strictly Rising physical exam:no:. :: is not a dust'^trl measure, it Is an ittv tr'.ant means ox 'c'tt:irir.g the cf-rav. r-f : methods em 4. Anihrncosilicosis was found in about 23 per cent of 2.711 employees of three anthracite mining companies studied by the United States Public Health Service in 195.'-. s M: t- r:Ml II II h wZSfi&Ji *5*3;: '-to 29th A'ationa! Safety Congress About 63 per cent of those having antliracosiiicosis showed evidence of disability, compared with less than 10 per cent in the control group. Moderate and marked de grees of disability handicapped approxi mately 21 per cent of those with anthracosilicosis compared with less than 2 per cent of the men serving as controls. 5. The occupational groups in anthracite mining, arrayed by the Public Health Serv ice according to extent of physical impair ment, are (1) rock workers, (2) regular miners, (3) all others exposed to more than 100 million dust particles per cubic ioot of air, and (4) men in haulageways except rock workers. 6. The principal pulmonary disease in metal mines is silicosis and the chief menace in silicosis is tubercle infection. Apparently silica dust alone increases the liability to pulmonary tuberculosis. Joint studies made by the Actuarial So ciety of America and the Association of Life Insurance Medical Directors" revealed that there were 65 deaths where 6 were expected (about 11 times the expected number) from tuberculosis in 1925-1936 among a group of 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 among 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 cipal method of preventing these diseases is to eliminate as far as possible or reduce to harmless concentrations the dust in the breathing zone of the worker. 8. The aim should be to eliminate the dust entirely from the air breathed. Where this is not always feasible it may be possible to reduce the dust to a concentration that will not cause disability during a working life time. 9. Analysis of data collected by the Pub lic Health Service to determine safe limits of dust exposure indicate that employment in an atmosphere containing less than 50 million dust particles per cubic foot pro duces a negligible number of cases of sili cosis when the quartz content of the (iu-; ic-s than 5 per cent; when the silica cor. tent is about 13 per cent 10 to 15 n'.iil,(l; particles appears to be a sate limit. 10. The amount of harmful dust creattc by various activities in mining can be 4. 1 Coili-. Bull. i Collis. 0/ Br ;,.,.ira:ory , Pt termined by sampling the atmosphere ir their vicinity and counting and itlentifving the dust particles. Sampling of air is also; means of checking the efficiency of dust con trol measures. 1. Colli-. e-jnonaJ t. atrd with g Occupatio ^liine Si tic riH. IN'- M3- 11. The impinger is the dust-sampling in-trument used most frequently in the United States. 12. The dustiest operations in mining arc 1. Brundar .'sited Slate- Office o lie Health iiio-ure to bblic Heait: dry drilling, blasting of dry rock or ore. shoveling or mucking, loading ami Itaulaec. and machine coal cutting. 13. The principal measures for controllinr the ill effects of dust in mining operationare ventilation, wet methods, proper blam ing practice, the use of personal respirator} protection, and physical examination o' workers. 14. The efficiency of these measures in the reduction of the incidence oi dust diseases is attested by the experience in the mines oi South Africa where among the whole both i Sayers, *. and Adae IsonK Stine .xli Kaos*- tae JO. !').' -1JJ. JO pp. -. Dublin, id Miners a December I919-J0- p. t Colli-, iealth, Di-s 'gust. Hyp- 1. Sen. P: s:th Walebierculo.-i-: 2.>S7. of miners the liability to contract silicosis in U Office . 1936-37 was less by 65 per cent than it va VAraco-Stli in 1920-33. Among the "new Rand miners 'vied State who entered the industry by way oi initial examination since 1916 and who have besr exposed solely to the progressively impri"" ing occupational conditions that have ob tained since that date, the liability to fn' tract silicosis was less by 87 per -cent than, ettumj the similar liability among all miners work '-eau ing ior an equal period in 1920-23. These it. R, "new Rand miners" constituted 7/ per eer.. Am, sase: of all working miners examined. V'M2. A La Conclusion The mortality and morbidity 1 rc'rr`. inonary diseases arc excessive-iir-tne "" -^C-, industry as a result of exposure 10 amounts of dust in the air breathed. fore, control oi the dust hazard i- to prevent these diseases. N'o single oi control is applicable to all tions and processes, therefore, all 1 e of prevention must be practiced to success in the solution of the prob.e"1. I' Minina Sectior. 54 7 REFERENCES o lit *Edgar L. Occupational Dust Dis**>1* . gu|i. 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Experimental Silicosi*: Jour. Indust. H>piene, vol. 8, 1926, p. 491. 20. l-anza, A. J., and Vane. R. J. Industrial Dust* ami the Mortality from Pulmonary Dis ease : Am. Rev. Tuberc., vol. 39, 1939, pp. 419-436. 21. Cummings, Donald E., Downs. Robert N.. and Berg. Melvin. Tuberculous Lesions in Male Industrial Workers: Am. Rev. Tuberc.. vol. 39. 1939. pp. 439-455. 22. Union of South Africa. Report Upon the Work of the Miners' Phthisis Medical Bureau for the Three Years Ended 31st July. 1935: Pub lished by 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 Initia tive in Investigating the Dust Problem: Vol. 49. 1938. p. 717. 24. Bloomfield, J. J., and DallaValle. J. M. The Determination and Control of Industrial Dust: United Crates Public Health Bull. 217, 1933. 167 pp. 25. Brown, Carlton E.. and Schrenk. 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