Document zoJvbZaGwEpQQeGjZG1BzdgN6

FILE NAME: National Safety Council (NSC) DATE: 1937 Oct DOC#: NSC063 DOCUMENT DESCRIPTION: Transactions of the NSC - 26th National Safety Congress Congress NATIONAL SAFETY COUNCIL, Inc. KANSAS CITY, MISSOURI OCTOBER 11 to OCTOBER 15, 1937 Municipal Auditorium HONORARY MEMBERS A ssociation of Iron and S teel E ngineers Robert W . C ampbell L ew R. P almer OFFICERS (1937-1938) D. D. F ennell, President . C. W. D empesy, Vice-President for Finance and Treasurer H arry Guilbert, Vice-President for Membership F rank H . H arrison, Vice-President for Industrial Safety H on. H arold G. H offman, Vice-President, for Public Safety ' W alter S. P aine, Vice-President for Engineering A. V. R ohweder, Vice-President for Local Safety Councils A. W. W hitney, Vice-President for Education W. H. Cameron, Secretary and Managing Director EXECUTIVE COMMITTEE (1937-1938) H. W. A nderson, General Motors Corporation J. I. B anash, Past President C. W . B ergquist, Past President H enry-W . Boggess, Petroleum Section C. B. B oulet, ASSE-Engineering Section H . W. Boulton, Automotive and Machine Shop Section H arold S. B uttenheim, The American City Magazine W . H . C ameron, National Safety Council, Inc Robert W. Campbell, Past President Robert L Ca t u n , Aetna Casualty & Surety Company R. A. Chaffin, Metals Section L ewis A. D eB lois, Past President C. W . D empesy, The Liquid Carbonic Corporation ^Marcus A. Dow, Past President D. D. F ennell, Consulting Engineer John B. Gibson, Western Electric Company H arry Guilbert, The Pullman Company F rank H . H arrison, International Harvester Company P. L. G. H asskarl, Lehigh Valley Safety Council H on. H arold G. H offman, Governor, State of New Jersey S. B. H orrell,. Food Section W alter G. K ing, P a st President OFFICERS A N D DIRECTORS, Continue Wit, C. Knoelx, Milwaukee Safety Commission John E. LoNC,Pa*tPresident -^ i'-C"'. ' Z!'-. '!S ' vfL T hos. H. M acD onald, U. S. Department of Agriculture W alter B. M artin, Peoria Association o f Commerce Safety Council I. W. M illard, Industrial Gloves Company 'J H H arold LVM iner, E . I. du Pont de Nemours & Co. ` P rof. R oger L. M orrison, Street & Highway Traffic Section E. J. O 'B iuen, Jai, Louisville Safety Council ' W alter S. P aine, A etn a L ife & Affiliated Cos. L ew R. P almer, P u t President ^ C. E, PernsoN'i, Past President A lbert S. Regula, Industrial 'Relations Counselors, Inc. '. ' Lt, CoiT H r a ^ ' ' R j i t ^ ;'; A . V. R ohweder, Duluth, Missabe & Iron Range Railway Co. George E. S anford, General Electric Co. Charles B. Scott, Past P r e s id e n t : Gen. J ohn H . S herburne, Massachusetts Safety Council J udce L ee E. S keel, Cleveland Safety Council . C W. S mith, Standard Oil Company (Ind.)' W alter D ent S mith, Delaware Safety Council; R. T. S olensten, Elliott Service Company C. P. T olman, Past President / * George G. T raver, Greater Chicago Safety Council, Inc. D r. C. H . W atson, Past President A . W . W hitney, National Conservation Bureau T . A. W ilson, Textile Section W . E. W orth, International Harvester Co. A rthur H. Y oung, Past President . DIRECTORS (1937-1938) G eorge J. A dams, Paper and Pulp Section \ H . W. A nderson, General Motors Corp. A. L. A rmstrong, Eastman Kodak Company H. K. B ailey, Chattanooga Safety Council J. I. B anash, Consulting Engineer Carl B arker, S t Louis Safety Council G. J. B arrett, Mining Section E rnest W. B eck, United States Rubber Products, Inc. C. W. B ergquist, Western Electric Co. E , F. B lank, Jones & Laughlin Steel Corp. H enry W. Bocgess, Petroleum Section 1 H . E Bolt, South Bend G vic Safety Council Iv i Tf. ' I' O FFIC ER S A N D D IR ECTO R S, Continud C. B. Boulet, ASSE-Engineering Section H. W. Boulton, Automotive & Machine Shop Section F. S. B rown, Standard Accident Insurance Co. W. A. B rown, Safety Department, Nashville Chamber of Commerce W. T. Buckeridge, Employees' Publication Section S. W. Burchiel, Safety Department, Automobile Club of Rhode Island H arold S. Buttenheim, The American City Magazine B. J. Callachan, Contra Costa County Safety Council W. H. Cameron, National Safety Council, Inc. Ray Carney, Kenosha Safety Council Robert I. C atu n , Aetna Casualty & Surety Co. R. A. Chaffin, Metals Section K enneth B. Colman, Seattle Traffic & Safety Council J. E. Culuney, Bethlehem Steel Co. L ewis A. D eBlois, Consulting Engineer . J ay E. D ecker, Mason City Safety Council C. W. D empesy, The Liquid Carbonic Corp. J ames B. Douglas, The Philadelphia Gas Works Co. D r. L ouis I. D ublin, Metropolitan Life Insurance Co. O. M. E dwards, J r., Safety Div., Syracuse Chamber of Commerce W. P. E lstun, Public Utilities Section D. D. F ennell, Consulting Engineer D. L. F ennell, Kansas City Safety Council D onald A. F inkbeiner, Toledo Safety Council Dr. H art E. F isher, Citicago Rapid Transit Co. Chester C. F isk, Berkeley Traffic Safety Commission H oward B. F onda, Burroughs Wellcome & Co. (U.S.A.) Inc. A lexander F oster, J r., Quarry Section J ohn B. Gibson, Western Electric Co. H oward F. Gilbert, Elizabeth Safety Council Otho M. G raves, The General Crushed Stone Co. W. A. Griffin, American Telephone & Telegraph Co. H arry Guilbf.rt, The Pullman Co. I saiah H ale, The Atchison, Topeka & Santa Fc Rv. Co. C. H. H arper, Refrigeration Section D. T. H arrington, U. S. Bureau'of Mines F rank H. H arrison, International Harvester Co. P. L. G. H asskarl, Lehigh Valley Safety Council R, C. H aven, Commercial Vehicle Section G. T. H ellmuth, Chicago, North Shore & Milwaukee RR. Co. Chas. E. H ill, New York Central Lines H on. H arold G. H offman, Governor, State of New Jersey E. C. H olden. Ik.. Marine Section 6 O FFICER S A N D D IRECTO RS, Continued E verett H ord, Madison County Safety Council S. B. H orreu, Food Section H. C. H owsam, Power Press Section F red B. H unt, Cement Section M ajor N orman A. I mrie, Columbus Safety Council R. D. J ewett, Springfield Safety Council T homas P. K earns, Industrial Commission of Ohio T hos. L. K e u .ey, Paterson Safety Council i J . M. K errigan, Rubber Section W m. C. K noelk, Milwaukee Safety Commission W m. S. K nudsen, Detroit Industrial Safety Council C. L, L aF ountaine, Great Northern Railway Co. M illard C. L efler, Child Education Section Barney L evy, J r., Rochester Safety Council A, A ugustus Low, Brooklyn Safety Council T hos. H. M acD onald, U. S. Department of Agriculture W alter B. M artin, Peoria Association of Commerce Safety Council F. W . M atson, Minnesota Safety Council [ R. A. M cA rthur, Transit Section j '. M iller M cC untock, H arvard University i I. W . M illard, Industrial Gloves Co. ' J ames K. M iller, Grand Rapids Safety Council j H arold L. M iner, E. I. du Pont de Nemours & Co. R. B. Morley, Industrial Accident Prevention Assns. P rof. Roger L. M orrison, Street & Highway Traffic Section E rnest M urphy, Albany Safety Council E. J. O 'B rien, J r., Louisville Safety Council George C. A. O pp, The Detroit Edison Co. W alter S. P aine, Aetna Life & Affiliated Cos. L ew R. P almer, The Equitable Life Assurance Society of the U. S. David A. P atton, Newark Safety Council Mrs. G. M. P ei.ton, Evanston Safety Council Charles W. P endock, Safety Div. Milwaukee Association of Com mcrce i ^ C. E. P ettibone, American Mutual Liability Insurance Co. Gen. George B. P illsbury, United States Engineer Office A rthur P otterton, Hudson County Safety Council A lbert S. R egula, Industrial Relations Counselors, Inc. Lt. Col. H enry A. R eninger, Lehigh Portland Cement Co. Bestor R obinson, Eastbav Safety Council A. V. Rohweder, Duluth, Missabe & Iron Range Ry. Co. W alter R osenbaum, Western. Pennsylvania Safety Council G. E. Sanford, General Electric Co. Industrial Dusts W EDNESDAY MORNING SESSION O ctober 13, 1937 The meeting was called to order by Chair- York Gty, and Vice-President for Engineerman A. S. Regula, Executive Secretary, In- _ ing, National Safety Council, who introdustrial Relations Counselors, Inc, New duced the speakers. What Industrial Dusts Are Harmful? Why? I BySENIOR SURGEON R. R. SAYERS .Chief, Division of Indnatrial Hygiene, U. S. Public Health Service While dusts exist everywhere in the at mosphere, it has been recognized for cen turies that workers in certain dusty occupations are less healthy than those not so exposed. The number o f persons e x posed in dusty occupations comprises one' of the largest industrial groups. The occu pational diseases o f workers in dusty at mospheres have been found to be due to entrance o f dust into the system by inhala tion, by ingestion, by direct absorption through the sldn, by irritation o f the skin, or by a combination o f the foregoing. The suspensions o f .particulate matter in air have been broadly termed dusts, fumes, and smokes. Such a classification is neces sarily arbitrary, since the line o f demarca tion Iretween them is not very sharp, and the cliief differentiation is based on the size of the particles. Investigations by the Pub lic Health Service in dusty industries' re vealed that about 70 per cent o f the dust particles examined were between 1 and 3 microns in size, only about 20 per cent were less than 1 micron, and the median size was 1.3 microns. Industrial dusts are mainly less than 10 microns in size. However, fibrous dusts in the air, such as asbestos, have been found to contain particles as large as 200400 mircons in the greatest diameter. While, generally speaking, according to Collis, dusts are more injurious as their chemical composition differs from that of the human body, or from the elements of which the body is normally composed,' it is difficult to establish a comprehensive definition for toxic dusts. Soilmaim,* after analysts o f various definitions for poison, felt that it is very difficult to give a definition which will not be ambiguous in some eases, but believed that the following covers most o f the points which must be considered in classing a substance as such: UA poison is .any substance which, act ing directly through its inherent chemic properties, and by its ordinary action, is capable of destroying life, or o f seriously endangering health, when it is applied to the body, externally, or in moderate doses (to 50 Gm.) internally." Some dusts are known to be poisonous, while others, in the concentrations usually encountered, are comparatively harmless. However, it may be stated that breathing dust in high concentration is not desirable. According to Fairhall, the damage arising from the inhalation o f toxic dust may be either local or remote, and depends upon whether the material is a protoplasmic poi son, whether it is caustic in reaction, or whether it is absorbed into the blood stream and carried to other centers which are in turn affected.* It is now well established that exposure to certain kinds o f dusts, such as those con taining considerable quantities o f free silica, has increased the morbidity and mortality rate from respiratory diseases; while me tallic dusts, such as lead and its compounds, 85 86 Twenty-sixth National Safety Congress have been associated with general systemic poisoning.* Dusts may be swallowed with saliva, water, or food, and direct poisoning has been traced to absorption by this method; other dusts may act as irritants and produce affections of the skin, irritate mu cous membranes of nose, eyes and throat, often causing inflammatory diseases of these organs.* Some inorganic dusts are able to pene trate the deep lung tissues and arc sufficiently insoluble to be retained there. Some of these may be active in the human tissues, causing definite and permanent in jury'. while others are inert and may be retained for years, apparently without seri ous damage; some are gradually absorbed without causing pathological changes.' All inhaled particles are soluble, at least .to a small extent. If harmless, cell activity is stimulated so that phagocytes remove the dust. If the solute is toxic, the viability of the phagocyte is affected and an ineffective accumulation results. At the same time, further solute may diffuse into neighboring tissues, setting up an irritation and subse quent fibrosis. The nature as well as the solubility of the solute is an important fac tor, hut of two substances of approximately equal toxicity, the more soluble form causes the greater damage. However, sub stances of such low solubility as silica may ultimately produce extensive injury.4 Kettle has stated that harmful dusts, if inhaled into the lungs, may activate a latent tuberculous infection; they may exaggerate an active tuberculous lesion or a coincident infection. If sufficient quantities of a harm less dust are inhaled, some of it remains in the lungs and causes a mild degree of fibro sis merely through mechanical irritation, hut such fibrosis is never sufficient to inter fere with the function of the lung.* Some writers state that while the influ ence of nonpoisonous dusts on health is a debatable subject, abnormally high death rates from bronchitis and pneumonia arc sometimes attributed to chronic exposure to nontoxic dusts. Large amounts of dust are occasionally found in supposedly normal lungs, at autopsy.' According to Drinker, there arc four dif ferent types of reaction produced in man by the inhalation of dust. The first and most important are the pneumoconioses, such as silicosis and asbestosis, which cause specific l':ng pathology and often are followed bv pulmonary tuberculosis. The second type of reaction is caused by toxic dusts like lead, cadmium, and radium. A. third type of mal ady follows the inhalation of finely divided metallic fume particles such as zinc oxide, and is known as metal fume fever. The fourth reaction, allergic in character, is caused by breathing organic dusts such as pollen and certain types of pulverized wood and flour. In all four cases the sole cause of the disability may be dust inhalation, but the reactions from toxic dusts result from swallowing as well as from inhalation* For various reasons it is difficult to set up an absolute classification fo r dusts. Opinion is rapidly changing regarding socalled inert or harmless dusts and further investigation may prove some o f them to be injurious. Some dusts may have both a toxic and an irritant action; while on the other hand, the poisoning resulting from ex posure to a dust may be the combined effect of more than one mode o f entrance into the body. However, the following classification of dusts, according to physical character istics and physiological effect, is used for convenience. I. Organic Dusts Organic dusts arc those which contain carbon, and were originally supposed to come from organized substances derived from animal or plant life. Living dusts come under this classification, and are thought to be of the same order of size as industrial dusts, with which they are fre quently associated. Bacteria are usually b e -' tween O.S and 3 microns, except jn a few cases, such as the anthrax bacillus, which ranges from 1 to 125 micron in breadth and 4.5 to 10 microns in length and 10 or 12 microns in diameter. However, it is possi ble that the larger and heavier varieties, like the larger and heavier dust particles, settle due to gravity, and do not remain suspended in the air. Many thousands of organic substances, carbon-containing, are made synthetically by chemical processes, such as dyestuffs, explosives, etc. 1. N O N L IV IN G ORGANIC D U STS. As the name implies, these are comprised of nonviablc particles, which may or may not b'c inherently toxic or irritant, but which nevertheless produce untoward effects in the human organism. "Allergic" dusts, or those to which only certain persons arc or may I ndustrial Dusts 87 become hypersensitive, with resulting asthma, rhinitis, or other disturbances, are included in this classification. a. Toxic and/or Irritant. Toxic or irritant dusts are all organic dusts which produce untoward symptoms, either systemic or local. Those producing local symptoms are usually described as irritant; those produc* ing general or systemic symptoms are termed toxic. A dust may be both toxic and irritant In reported cases of injury or death fol lowing inhalation of dust from organic com pounds, among the chief offenders are patanitraniline, the dinitrobenzenes, chlorodinitrobenzenes, trinitrophenol, and nitronaphthalene. Eye damage due to inflamma tion of the cornea has occurred among workers exposed to methyl violet dust. The dust from paraphenylene diamine derivatives is particularly irritating and dangerous, causing not only a severe form of derma titis where the dust comes in contact with the skin, but also producing acute inflamma tion of the mucous membrane of the respiratory passages.4 Toxic du`.ts may be generated during the handling of powdered dyes and in preliminary dyeing operations, particularly the hydro-extractor process, ".here particles are disseminated in all di rections.11 Coal tar and indigo dyes are substances most frequently used. Cases of amblyopia have been reported from exposure to inhalation of tobacco dust." It has been found that inhaled to bacco dust exerts a nicotine action oh the organism fifteen' times greater than that produced by the same quantity of smoked tobacco with an equal nicotine content.11 Severe dermatitis is experienced by many workers handling powder containing T.N.T., which is used in making high explosives. Picric acid, which is also used for this pur pose. requires drying, and in this latter state has been found to produce a dermatitis. Picric acid is. also the oldest synthetic or ganic dyestuff.14 Dermatitis occurs among handlers of silk with varying frequency. Sails determined that a rash occurring among workers in a silk factory was due to dust from silk cocoons imported from Africa." Persons engaged in the manufacture o f quinine and quinine preparations suffer from skin phenomena, which occur for the most part on exposed parts of the body, and may be caused by ingestion or by quinine dust, or powder form of the preparation, ex erting a direct irritating effect on the skin." Dermatitis due to other vegetable dusts such as vanilla, powdered arnica, pyrethrum, etc., lave been reported.14 Dental lesions, of occupational origin, have been reported among workers in sugar. The gingivitis caused by sugar dust is clas sified as purely mechanical, with later- developing caries. Digestive disorders, respiratory conditions, and cutaneous con ditions (especially of the face) were also found." I Dock workers, transporters of grain, workers in grain and flour mills, etc. are exposed to dusts during their work. Dusts from cereals may contain many impurities, which may cause an irritating action on the respiratory passages, as well as inflamma tion of the skin. Digestive disturbances, dental defects, diminution in hearing, and conjunctivitis have been observed among millers, and have been attributed to the dusts to which such workers are exposed." b. Alltrgic. Many apparently innocuous substances may produce reactions in per sons of peculiar personal susceptibility. The term "allergy" is used to describe this con dition of hypersensitiveness or susceptibility, and allergic phenomena most frequently manifest themselves in skin reactions. How ever, they may cause acute reactions else where in the body. When the respiratory tract is involved we hare such well known diseases as hay fever or asthma. These diseases may develop as a result of hyper sensitiveness to such.substances as pollens from plants, horsehair, rabbit's fur, furs, feathers, etc. For instance, furriers, workers in clothing industries who are exposed to wool dust, etc., may suffer from hay fever or asthma." It is unnecessary for the offending dust to reach the depths of the lungs--giant pollens for example are reported to produce their effect after being caught in the upper res piratory passages. Should such an offending substance be finely ground it could reach the alveoli and as a result probably all physiologic reactions would be accelerated." In a survey of a plant where resin is mixed, ground, and molded, it was found that 80 per cent of the occupational derma titis there was due to hypersensitivity to hexamethylenetetramine and formaldehyde contained in the dust to which the workers were exposed.11 During the first processes 88 Twenty-sixth, National Safety Congress of cotton spinning, cotton-strippers are ex trichum dermatodes), which is scattered posed to dust arising from cotton husks and when the bark is stripped off. This powder debris, which produces a typical form of is irritating to the skin and mucous mem asthma.' branes. Mycelia and spores of moulds are Ordinary wood dust has been of interest due to its purely mechanical action, but still greater care is required in handling certain kinds, especially woods coming from abroad, because of the essential oils impreg nating them, which when freed in the dust may affect the health of the workers con cerned. Some of the woods capable of causing skin lesions arc Brazil wood, satin- commonly found to cause rashes; for in stance, the black powder coming from macerated sugarcane stalks. Among basketmakers, the mycelium and spores, in the form of a white mould (hyphomycete) from the rhattan canes used, get shaken out when the canes arc split, hammered, and cut, causing painful fissures to develop on the skin where they alight.5* wood, teakwood, cumaru or tonka wood, A form of asthma or spasmodic cough, black ebony wood,' West Indian mahogany, suffered by cotton weavers and known as Japanese tagayasan, coccoloba, chestnutwood, aspergillosis, has been considered due to in olivewood. California sequoia, etc. All per halation of spores of a mildew which some sons who handle these woods are not in times occurs on the threads." In a study jured, only those particularly susceptible to of silicosis among miners, made by the the substances they contain becoming Public Health Service, a number of cases affected.* of typical miliary calcification were en countered. Unstained smears of those cases 2. L IV IN G ORGANIC D USTS. These examined were positive for fungus, two contain particles capable of exhibiting the types of Aspergillus fungi being identified. phenomena of life* (especially the property All of the subjects but one were farmers, of reproduction or multiplication), such as teamsters, feedmill workers, or residents of bacteria and fungi. They are usually found small agricultural towns where grain is in low concentrations and are associated marketed. Farmers are exposed to fungi in with nonliving dusts in the air. threshing wheat, baling hay, or handling a. Bacteria. One of the most important various small grains." among these is the anthrax bacillus, which Some other fungus diseases such as actino is contained in the dust from skins, furs, mycosis and blastomycosis are associated wool, and animal hair, horns, hoofs, bones, with occupational exposure to dust. The etc. This disease may occur in two forms: former occurs among workers handling cutaneous (in which the organism affects straw, hay, grass, vegetable debris contami the skin), and f>uimonary (when it is inhaled, nated with mould, etc. Actinomycosis is as in the form of anthrax known as wool- likely to affect people engaged in commercial sorters* disease).15 handling, storing, and cleansing of grain Cases of tetanus, reported in connection (grain distilleries, flour mills, grain crush with jute manufacture, were traced to the ing, breweries, and malting houses, etc.).* raw material, the bacillus having been found in the factory dust." Diphtheria, tubercu II. Inorganic Dusts losis, smallpox, typhoid, or other bacillus- produccd diseases, may result from exposure to infected dusts. Inorganic compounds are ot mineral origin, not requiring a living organism to produce them." A number of dusts not Bacterial sensitization can be the cause of usually classed as toxic may, under some any of the allergic diseases, namely, asthma, conditions, produce untoward effects on the perennial, hay fever, urticaria, angioneurotic human organism. Classified under inorganic edema, eczema, or migraine headaches.** are toxic and/or irritant, fibrosis-produc b. Fungi. Dusts containing the mycelia ing, and nonfibrosis-producing dusts. and spores of parasitic fungi give rise to a. Toxic and/or Irritant. Toxic dusts are annoyance and discomfort. "Maltster's" itch those which are inherently toxic when in from the dust alone has been reported. In haled, ingested, or otherwise absorbed. Provence, reeds used .for ceilings are stacked Among those which produce systemic poi while still wet and undergo fermentation; soning, some of which are also irritant, are they become covered with a white powder the dusts from heavy metals and their salts, (a dry fungus of the Mucor family: Sporo- such as lead, mercury, arsenic, cadmium, im htslfi&l Dusts ................" ~ 89 zinc, etc. Irritant dusts are injurious by reason of their strong irritative or corro sive properties. j As a rule, inhaled irritant substances im mediately cause a reaction in the upper respiratory tract of such severity that they are prevented from reaching the lungs, al though they may cause lung damage by extension of inflammation if the mucous membrane is corroded.' Lime, calcium oxide, and the di-chromates- are examples of irri tan t dusts. An inorganic dust may possess both toxic and irritant properties, and the poisoning produced may be the combined effect of more than one mode of entrance .into the body. Of the directly poisonous dusts, the most widely prevalent are those of certain lead compounds, particularly the oxide, carbon1ate and the chromate. The dust is readily i absorbed by the mucous membrane; some i dust passes into the stomach and is dissolved 1by the gastric juice.* j According to Fairhall, perforated nasal j septum is a common occurrence among j workers with bi-chromate dusts.* In a ; study made by iiie U. S. Public Health Service it was found that continuous daily exposure to concentrations of chromic acid mist greater than I milligram in 10 cubic meters is likely to cause definite injury to the nasal tissues." It is believed that a similar concentration of the dust would be equally toxic. In the case of poisoning from some heavy metals, exposure may be to both dust and vapor. For instance, investigations have shown the safe, limit of total exposure' to lead oxide dust and fumes to be less than 1.5 mg. per 10 cubic meters of air, except for prolonged exposure." In exposure to mercury dust and vapor, it was shown that the incidence of chronic mercurialism in creases rapidly with increasing mercury concentration, after such concentration ex ceeds 2.0 mg. per 10 cubic meters." Alkalis and metallic oxides are common causes of dermatoses. Lye, potash and lime are known to cause irritation to plas terers, cement-makers, bricklayers, masons, stonecutters, modellers, and metal platers." Ulceration and perforation of the nasal sep tum occur among workers exposed to the dust of soda ash; systemic poisoning also occurs from inhalation of calcium cyanimide dust." Cases of dermatitis, scleroderma and can cer are reported to have been caused by exposure to dust of arsenic compounds. Certain aluminum salts are skin irritants and aluminum dusts may contribute to the infection of skin and mucous membranes, through mechanical action." b. Fibrosis-Producing Dusts. The most important of these are the inorganic, slightly soluble dusts which cause fibrous changes in the lung tissues, some of which are seri ous, and some of which cause little or no disability.' So far as is known, no inorganic substances other than silicon derivatives cause more than a very moderate degree of fibrosis of the lung. Moreover, there seems to be no evidence that any other constituent of ordinary dusts can influence so unfavora bly a pulmonary infection.* Although other dusts, when inhaled in sufficient concentrations over a long period of time, have been shown capable of pro ducing a pulmonary fibrosis, nevertheless, the pneumoconiosis characterized by nodu lar fibrosis has to date been shown clini cally and experimentally to be associated only with the inhalation of dusts containing free silica. Since this dust, to exert its harmful action, must enter the finer divisions o f the lung, the particle size of the atmospheric dust may bear a definite relationship to the in jurious effect produced. The silica must be present in the air in particles small enough to enter the finer air -spaces and of such dimensions that the phagocytic cells may engulf them. The greater majority of par ticles found upon microscopic examination of the lung fall within the limits of from 1 to 3 microns." Examples of siliceous dusts are granite, quartz, sand, pumice, slate, etc. In a recent study among anthracite miners, the correlations between exposure to dust (which contained silica) and the evidence of constitutional changes left little doubt as to the etiological significance of the dust in the air breathed. Like correlations were found between the silica exposure and the extent of pulmonary changes." When the inhaled dust -consists of silica combined with bases, silicates, some degree of change in the pulmonary tissue may result. In this respect asbestos dust seems to be unique among silicates in the prevalence and se verity of the disease it causes." The chief distinction between silicosis and conditions due to simple reactions caused by other dusts is the active proliferative 90 7'tecnty-sixtJi Xational Safety Congress reaction in the tissues which results in progressive nodulation. Silicosis, when once established, strongly predisposes the lungs to infection, especially with the tubercle bacillus. Chronic interstitial pneumonia, chronic bronchitis, and emphysema arc fre quent complications of advanced degrees of silicosis. The relation of the acute respiratory in fections to the reaction due to dusts other than free silica has never been established, though a heightened incidence has often been shown statistically in workers in dusty trades. It is fairly certain that a dust dam aged lung, whatever the cause, fares much worse if an acute infection does supervene upon it.' In a study conducted by the U. S. Public Health Service among marble finishers in \ ermont, it was found that marble dust when inhaled in the concentrations found in the examined plants produced a mild, bi lateral, linear fibrosis in some cases, but no serious lung changes were noted and there was no disability. due to the dust, even after years of exposure.** c. Nonfibrosis-Producing Dusts. These are inert, that is, they do not cause fibrous tissue to be produced, but .may liecome encapsulated or lie free in the tissues; or they are absorbed without production of fibrous tissue. Included among them are alundum, coal, corundum, emery, limestone, magnesite, marble, plaster of paris (gyp sum). and polisher's rouge. Dust Control Engineering and medical control arc the two most important factors in combating the industrial dust hazard, and arc to a large extent complementary.' Engineering Control. ,\< Lanza" has Mated in a recent paper, "it is a basic principle in dealing with a dust hazard that the dust should be attacked at its point of origin and thus prevented from being dis seminated into the atmosphere." After the dust has been spread throughout the air it is difficult to deal with it, and reliance must be placed on individual protection, which is never wholly satisfactory. Lanza further cites various methods used in controlling dust. These will be reviewed but briefly, since a paper dealing with the subject of dust control.in detail, will follow on this program. Dust may be entrapped at its source by suction devices and thus removed and col lected. Familiar examples are exhaust hoods in grinding operations, arid the devices used in rock drilling. Generally speaking, the exhaust ventila tion method, where applicable, is to be pre ferred in controlling a dust hazard. Water may be used to entrap dust and prevent its dispersal, and under certain circumstances it may be of advantage to combine the use of water and the use of suction. Sometimes a dusty process can be completely enclosed in a sealed room or compartment. It must be remembered, however, that any mechani cal device of this kind offers adequate pro tection only if it is properly designed, installed, and maintained. A great deal of attention has been given the subject of individual protection from dust, and there are many types o f respira tory protective devices now- available. These are generally of two types; those which provide fresh air from an uncontaminated source and those which rely upon a filtering medium for removing dust from the air breathed. Where the use of such a device is indicated, only one of the types approved by the U. S. Bureau of Mines should be used. As a rule, it may be said that masks, respirators, or other such protective device should be used only where exposure to the dust is intermittent and brief, or where some unusual condition makes a more ade quate dust control impracticable." Where bacteria or other living dusts in the air are associated with a process, steri lization methods such as increased tempera ture, ultraviolet radiation, and chemicals like chlorine or other bactericidal substances, may be of use. Pasteurization temperature (about 140 F.) will kill most organisms except those bearing spores. Steam disin fection is used for horsehair, and proves to be practicable if the temperature does not exceed 230 F. Wool fibres, however, lose their elasticity by steam disinfection, and the "Duckering" process now used in Eng land includes soaking of the wool in a form aldehyde solution, and drying in a current of air at a temperature of 160 F." There are few occupations in which there would be a sufficient concentration of dead bac teria to cause untoward effects in man. In the case of dusts producing external irritation, auxiliary protective measures may include the use of protective clothing, Industrial Dusts ...._ TM .91 gloves, goggles and aprons; as well as pro tective salves, ointments, or other com pounds to delay or diminish the' irritant action. General rules for hygiene and good housekeeping should also be observed. Medical Control. Equally important, and closely interrelated with the engineering phase, is medical control of occupational hazards. In addition to directing the proper placement of new workers, and guarding the health of all employees, medical control is a check on the efficacy of the engineering control methods already instituted, or a measure of the need for new protective de vices. It has been stated that "Industry has found that the best way to treat industrial injuries and illness is to prevent them,"" and medical control, through preemploy ment and periodic physical examinations, is one of the most important factors in such prevention. The preemployment examination is made to determine the employee's physical and mental fitness for work. It serves to dis close the presence of any contagious dis ease, reveals any minor physical defects which might later become serious, or whether the examinee's condition precludes his em ployment in certain or in all types of work. It should be remembered that such preem ployment examinations are not to be made for the purpose of eliminating an employee, but rather for allocating him to the type of work for which he is physically suited. A worker should be given employment unless totally unfit, or unless his disability, even though slight, would cause him to be a haz ard to himself or his associates. Further more, the practice of preernployment examinations should be extended to include executives and officials of industrial organi zations. "The purpose of periodic physical examinations is to secure and maintain physical fitness and thereby lengthen work spans."" Reexamination of employees some times results in the discovery of defects and disabilities which were not observed at the time of employment. In such cases, an oc cupational adjustment should be made to provide continued employment, but remove the.risk of permanent injury. Reexamination of employees is required by law in certain occupations in which the handling of poisonous or otherwise deleteri ous substances mav result in the contraction of disease." Since some occupational dis eases tend to clear up and recur, records of previous occupations should be included in the physical examinations. The frequency of examinations should be determined by the medical director, unless otherwise speci fied by law. Those exposed to known occu pational disease hazards may have weekly or monthly examinations." "It should always be kept in mind that the basic principle of physical examinations in industry is to keep men on the job and not allow the physical examination to be merely a weeding out process."" R eferen ces 1Bloomfield, J. J. and DallaValle, J. M. ``Tlic Determination and Control of Industrial Dust." 17. S. Public Health Bulletin No. 217, April, 1935. >Collis, Edgar L. "Industrial Pneumoconioses, with special reference to Dust Phthisis." Milroy Lectures, 1915. H. M.S.O., London. * Sollmann, Torald. " A Manual of Pharma cology." W. B. Saunders & Co., Philadelphia, 1932. 4 Fairhall, Lawrence T. "Toxic Dusts and Fumes." Journal of Industrial Hygiene and Toxi cology, November, 1936. * Bloomfield, J. J. " The Sampling and Analysis of Industrial Dusts." American Public Health Asso ciation, Yearbook, 1935-36. 4 Gibbs, W. E. " Dust H atard in Industry." Ernest Benn, Ltd. London, 1925. I Air Hygiene Foundation of America, Inc. "Sili cosis and Allied Disorders." Medical Series, Bulle tin No. 1. Pittsburgh, Pa. April 15,1936. 4 Kettle. E. H. ``The Action of Harmful Dusts." Inst, of Mining and Metallurgy, London, June 14, 1934, * " Duals, Fumes, and Smokes." Occupation and Health Series, International Labour Office, Geneva. 1930. " Drinker, Philip. " Causation of Pneumoconi osis." Journal of Industrial Hygiene and Toxi cology, October, 1936. u "Dyeing." Occupation and Health Series, International Labour Office, Geneva, 1930. u Legge, Sir Thomas. "Industrial Maladies," Oxford University Press, London, 19341 u Burstein, A. " Nicotine Action from Inhaled Tobacco Dust." Journal of Industrial Hygiene, De cember, 1927. 14White, R. Prosser. " The permatergoses. or Occupational Affections of the Skin." H. K. Lewis & Co. Ltd., London, 1934. ** Schwarts, Louis. " Skin Hazards in American Industry." U. S. Public Health Bulletin No. 215, October, 1934. *4 Downing, J. G. " Industrial Dermatoses: Treat ment and Legal Aspects: Review of Recent Litera ture." Journal of Industrial Hygiene and Toxicology, July. 1935. II "Occupational Lesions in Workers in Sugar." Belgium Letter, Journal of American Medical Asso ciation, Sept. 10, 1927. Abst. Journal of Industrial Hygiene, February, 1928. 14"Flour Mills," Occupation and Health Series, International Labour Office, Geneva, 1930. '* Mayers, May R. " Susceptibility to Dermatitis," The industrial Bulletin, Albany, N. Y. Feb. 1937, vol. 16, no. 2. M Drinker, Philip, and Hatch, Theodore. "Indus trial Dust." McGraw-Hill Book Company, Inc., New York. 1936. 41Schwartz, Louis. " Skin Harards in American Industry. Part II." U. S. Public Health Bulletin No. 229, Sept. 1936. ** " Poisonous Woods." Occupation and Health Series, International Labour Office, Genera, 1930. 92 Twenty-sixth National Safety Congress _ ** E; W*i K tiu u , W., snd Stallybrsss, C. O. "Indtutrisl M edidnc and Hjrfiene." Brilliere, tln d l and Cox, London, 1923. Browo,_ C. T. "The Diagnosis o f Bacterial AjleriT- Southern Medical Journal, Vol. 27, No. 10. Oct. 1934. ** Sarcr, R, K. and Merewethcr, F. V. "Miliary Lunr Disease Doe to Unknown C atu e..U . S. Public Health Report*, Dec. 5, 1930. "Actinomycosis.'* Occupation and Health Series, International Labour Office. Genera, 1930. * Holland, J. W. "Textbook of Medical Chemistry and Toxicology." W. B. Saunders Company, Phila delphia, 1920. "Bloomfield, J. J. and Blum, Wm. "Health Has ards in Chromium Platin*." U. S. Public Health Smvice Reprint No. 1245, Washington, 1930. " Russel!,* -- * -- son. ____ U. S. Public v. AU3. i u u c , jyjj. Neal, , Jones, Bloomfield, Dallt v alle and Edwards. A Study o f Chrome Mercurialitm in the Hatters* Fur Cimine Industry. U. S. Public Health Bulletin No. 234, May, 1937. MSayers, R. R. and Jones, R.*R. "Silicosis and Similar Dust Diseases.'' National Silicosis Con ference, Washington, D. C , April 14, 1936. ** Sayers, Bloomfield, DallaValle, Jones, Dreessen, Brundaee and Britten. "Anthraco-Suicosii amon* Hard Coal Miners." U. S. Public Health Bulletin No. 221, December, 1935. " Middleton, E, L. "Industrial Pulmonary Dis ease due to the Inhalation of D u st" The Lancet, July 4 and 11, 1936. MDreessen, Waldemar C. "Effect o f Inhaled Marble Dust as Observed in Vermont Marble Finishers." U. S. Public Health Service Reprint No. 1630. * Lanza, A. J, "Control and Prevention o f Sili cosis." Symposium on Silicosis. California Tuber culosis Association, San Francisco, 1937. "N ew tm ist, M. N . " Medical Service in Industry and Workmen' Compensation Laws." American Collece of Surgeons, Chicago, 1934. _ ** "Medical Care of Industrial Workers." Nstional Industrial Conference Board. Inc. New York. 1926. The Engineer's Part in Eliminating Dust Hazards By A R TH U R S. JO H N SO N Assistant to Manager, Engineering Department, American Mutual Liability Insurance Co., Boston, Mass. W hen one realizes that control of the dust hazard depends upon the combined contribu tions of the physician and the engineer, he ap preciates that the solution requires scientific treatment. By scientific treatment I mean the technical analysis of the hazard to discover the causes which contribute to injury or ill health, and the development of control meth ods which obey physical law and physiology, and which will be directed at causes that admit of most immediate and economical treatment. That goes for handling the dust hazard in a given plant It goes double for acquiring knowledge to the end that the whole problem may reach ultimate solution. Right now our knowledge of the problem is in big chunks, loosely put together and largely empirical. There are estimates only to judge the mag nitude of the dust health problem, and it is so closely associated with other health problems that a clcan-cut estimate of it alone is imtxjssiblc. Wc do know that it is great in the aggregate, and for the individual plant it may be very bothersome and expensive. What actually makes quartz dust cause silicosis is not known. It does, so the air breathed by workmen must not contain harm ful quantities of respirable quartz dust. Inex pensive methods for making the air clean are still in the realm of dreams. Much work must be done to know more about silicosis and more how to make atmospheres safe inexpen sively. As an accident prevention job, dust control lies almost entirely within the admin istrative responsibility. The control measures are capital expenditures of considerable size. A plant with a dust hazard is sick, it needs an expert diagnosis and scientific treatment, which may include expensive major opera tions. Home remedies are seldom much good, and supervision and employee safety con-' sciousness alone cannot accomplish anything. There may be observed in countless shops installations for exhausting dust which are derisively called "tin knocker" jobs in which the horsepower dissipated is out of all pro portion to the air-borne dust moved. Tonnage efficiency of material moved may be the proper yardstick for pneumatic conveyors but if the material to be moved is air, contaminated with nearly weightless particles of dust, the entire health hazard can He in the half of one per cent of material not moved. I do not mean that unless a dust supression job was'engineered it can be no good. There are many good installations that were never figured at all but grew like Topsy. The re Industrial Dusts 93. suiting freedom from dustiness was so satis factory that efficiency held little interest to the owner. This is exceptional, however, and I offer the opinion that dust suppression jobs should be engineered. A dust-suppression installation is a safety device, designed and operated to provide pro tection against possible disease and provide a sense of security which must be absolute. Its safety is not rushing air and rattling chips but a minimal residual dustiness. There is no more pathetic defeat for a dust control job than to find faith in its effectiveness so low that workers must wear respirators to find the reasonable safety that was expected from the hoods, ducts and fans. Diagnosis and-Control Let us examine some of the features by which we recognize this dust hazard problem, leaving out the soao-legal aspects. In order to develop more fully the engi neer's place in this dust control program, it seems desirable to separate as sharply as wc can the diagnostic considerations from those which deal with control. In the first com partment wc can place all the analytical com ponents which describe the hazard and its exposure, the probability of its producing ill health and all the rest of the medical and industrial hygiene facts which make out a case against the existing dust. In the second compartment* place the knowledge of physics and engineering necessary to plan the dust control program and so design it that when installed its performance follows prediction that the probability of industrial disease is reduced to insignificance. The Industrial H ygienist Our first feature of interest would naturally be the specific and relative toxicity of silica, silica-bearing and other dusts which make up the dust health hazard. Much might be said to advantage about the quality and quantity of hazard in many dusts. The acquiring of this knowledge has been, and must remain a medical problem. It involves gross and micro scopic pathology and x-rays, and experimental animals. Engineers do not talk that language. Industrial hygienists do; they are a happy combination, half doctor and half engineer. Many of them are quite capable of handling the dust health hazard in all its phases of investigation and control. For the purpose of this discussion I throw their interest in with the doctors. I want to go so far in my opinion as to state that the engineer should not attempt to define the quality of health hazard-in a given plant or industry,.nor should he establish threshold limits of safe or permissible dusti ness. This may be debatable, but I shall con tend that the engineer who writes the speci fications of hazard and dust tolerance is really an industrial hygienist, and is using a very much broader knowledge than engineering alone. In the first case the quality of the health hazard is an opinion arrived at after studying all the environmental conditions including the general sanitation, occupational analysis and a scientific analysis of the- dust exposures. In the exploration of dust exposures, the nature of dusty operations must be viewed from physical, chemical and mechanical aspects, the determinations of dustiness must be not only counted and classified by particu late sizes,, but chemically and mineralogically analyzed. The plant layout must be studied with respect to dust production and distribu tion, and the housekeeping and existing dust control equipment evaluated. The presence of specific hazards, such as toxic gases, abnor mal temperature and humidity conditions, etc., must be explored for their complicating effect upon the whole picture. This is distinctly an industrial hygiene job, and some of the most critical data requires only medical viewpoint. This is absolute in the case of tuberculosis study and the qualifying of men for employ ment So far, not one atom of engineering to suppress dust is involved. It is entirely anal ysis of hazard. The diagnosis must be that the dustiness is hazardous to health or that it is safe. If it is hazardous, it must be brought down to a specified residue. If it isn't leave it alone. On the second point if the hygienists can not specify threshold limits graduated upward for relatively less hazardous dusts, let the engineer not worry about i t The diagnosis is dust which is harmful and too much of it. The remedy is control of the dust. The engineer designs controls which will produce the lowest practical residual dusti ness. H e should not attempt to write his own specifications of threshold limits or permis sible dustiness. This may be an important goal in the study of dust health hazards. Safe Limits At the present time the medical men and hygienists believe that quartz dust is safe 94 Twenty-sixth National Safety Congress l>clow five million particles. They seem will: trical phenomena which bear upon dust be mg to graduate upward to 20 million for havior. medium silica and 50 million for low silica Those are all principles of physics which l>ereentages. Five million particles is virtually explain the behavior of dust and upon which dust free, and is very difficult and expensive engineering practice must be based. They to achieve and maintain. The declaration of must be understood and be taken into account. safety of the installations must remain in the Dust control is not a matter only of general hands of the medical and hygiene groups in ventilation; the engineer must study the pro whose hands now lies the responsibility for duction as well as the dispersion. The problem determining the hazard. should be analyzed to determine the applica We-uow enter the chapter of our discussion bility of segregation, enclosure, wetting, local intended to demonstrate that dust control is exhaust and general ventilation. an engineering job, that it must be given In some instances, substitution of non-hazscentinc treatment, not guess work, applying ardous material, or non-dust-producing oper engineering methods which are based upon a ations may have specific application, and they knowledge of physical law, the behavior of should be explored first. This implies plant dust, the performance of air-moving machin engineering. I am convinced that many bad ery, etc. installations are bad because plant engineering Prerequisite Knowledge was not used. In the designing of exhaust systems installed to capture the dust at the Let me recite briefly, a few of the things which, in myi opinion, the engineer should know to do this job correctly. He must know how to make a survey. Surveys depend upon sampling, and sampling is not a catch-ascatch-can proposition. It involves the place, the time, the frequency, the amount in a sam ple, and the number of samples so that .maxi mum, minimum and average data mean some points of generation, the physical behavior of air proving toward hoods and in ducts must be known, and that knowledge used. Each system must consist of collection hoods, pip ing, air-cleaning plant and a source of suction. Before selecting a hood for a job the engineer must know dust'dispersion by dynamic pro jection as well as dust dispersion by air cur rents, and design the hood accordingly. thing, so that credibility can be given them. Knowledge Needed l*or the type of sample involved he must know how to weigh or count respirable dust, The aero-dynamic characteristics of suction as distinguished from large masses of non- hoods appear to be little known because little respirable dust which complicate the picture. thought was given to them in designing He must know how to observe the sources of thousands of hoods which can be found every dust floods as distinguished from conditions where in industry. All the possibility for of normal dustiness. He must know the entrapping dust and much of the efficiency of sources of dust and the principles involved the system lies in this factor. Air velocity, in the dispersion of dust. He must determine static suction, and rate of air flow are all how much dust enters the problem l>ecausc it . related, and they must be known. It is essen is part of the material, and what dust is tial to use high velocity of air in certain types created in. the process by the fracturing of the of exhaust systems to entrap dust projected material. at high velocities as in the case of a granite Any less survey cannot tell the engineer what his task of dust control is. To visualize that task intelligently he should know the physics of Brownian motion, laws of resist surfacing machine, and low velocities must be used in others, as in the case of cleaning asbestos fibre of dust to prevent wasting material. ance to the motion of particles moving in air, Quantity of air and its velocity must be l>oth when the air is in turbulence and for determined, then the piping should be de stream-line motion. He should know terminal signed to take into account the behavior of velocities, movements due to centrifugal mo air-flow through pipes at low and high veloc tion ; flocculation and the effects of air motion ities. Where the problem is complicated by and the effects of humidification on it. He the large sized particles which go along with must know all about the difficulties of wetting the fine dust, how these behave must be taken and what is known about overcoming these into account. Pressure losses are very impor difficulties. He should know the several elec tant j elements in the design of an exhaust / / ndustrial Dusts' ................... ........ 9a system. Loss at the hoods, loss at the bends, and loss in the ducts must not be guessed at. Pipe design must take into account the gage of the metal and reinforcing to withstand pressures and erosion. The selection of a fan and its motive power is a matter of calculation, not guess work. Power consumption in the system is calcula ble, fans follow certain laws, so the engineer must know the behavior of axial flow, pro peller type, radial flow, paddle wheel and other fan performance. More physics and engineering calculation goes into the air-cleaning apparatus. The selection 'of gravitation, inertial or filtration method depends upon what the dust is, the calculation for any methods requires knowl edge of discharge through stacks, the deter mination of sizes of settling chambers; the behavior of cyclones. The use or non-use of a filter, and if so, what type, how it should perform, how big it should be, what kind of resistance and how much each kind offers, to say nothing of their proper location with relation to cleaning, accessibility, etc., are all items for accurate engineering determination. Apparatus to check the behavior of installa tions must be known and used. Performance cannot be left to guess work. Supplying suffi cient air to be exhausted is part of the prob lem. The same may be said of heating. Do I give the problem too severe a build up ? I think not. Remember these two things: 1. You are dealing with hazardous mate rial so small in size and so little of it by weight that it is as invisible as the air that bears it. 2. Physical laws involved in the behavior of dust and air do not permit inexpensive methods of control. I am acquainted with budgets set up for this purpose which amount to more than a quarter of a million dollars, and I know of many where 60 to 80 thousand dollars is involved. The need for this much engineering is rec ognized by men who know. Already much has been done toward getting the knowledge into handbook shape. Perhaps the best job of tilts sort to date is "Fundamentals Relating to the Design and Operation of Exhaust Systems" developed under American Stand ards Association procedure. The Doctor's Part in Controlling Dust Hazards B y A. D. L A Z E N B Y , M.D., F.A.C.S. Chief Surgeon, Maryland Casualty Co., Baltim ore, Maryland Considerable confusion has existed in the past as to just what is the physician's func tion in the prevention of dust diseases, and just wh^t is the engineer's. It is very ob vious upon even casual thought that the two sciences must work hand in hand in their efforts to solve the problem, The physician through his special training must be able to tell the engineer what dusts are dangerous and what are not. He must know how those dusts enter the body and the manner in which they do their harm. He must be trained in the examination of per sons who are to be employed to work in dust, and to discover those who are already diseased, or are peculiarly susceptible to dust disease. He must be able to detect the first signs of disease in workers who are exposed to dust, and must be prepared to recognize the disease when it is fully de veloped. It is not necessarily the physician's func tion to analyze dust. That is a task for the chemist and the petrographer. It is not the physician's function to count the particles of dust in a given industrial atmosphere. That, in reality, is the function of the engineer. It is not the physician's function to devise ventilating equipment for the removal of dust, nor even to be more than an adviser as to the means that must be adopted to render the atmosphere safe. The physician nevertheless must correlate with his medical knowledge and with his studies of the industrial worker the findings of the engineer. A diagnosis of silicosis, for example, requires not merely characteristic occupational history and characteristic physi- % Txvcnty-sixth National Safety Congress cal fitidHigsrbut'ihc"fcnowlcdge"as' well thar the patient has been exposed to hazardous dusts in dangerous concentrations. All dusts when inhaled in excessive quantities may be considered as harmful, but only a few can be regarded as dangerous. From the standpoint of their dangerous properties, they may he divided into three general groups. 1. Those which are dangerous because of their poisonous action, such as lead, arsenic, mercury, and similar substances. 2. Those which cause only irritation in the respiratory tract, resulting in such condi tions as bronchitis or local inflammation; such substances as vegetable fibre, cork dust, flour, starch, and other relatively innocuous organic or inorganic materials. 3. Those which tend to produce fibrosis of the lungs, thereby predisposing to respira tory infections, especially tuberculosis, such dusts as asbestos, silica dioxide or mag nesium silicate. I shall confine my remarks chiefly to dusts occurring in the latter category. It has been generally believed that the harmful effects of dusts inhaled into the lungs depended more upon their physical structure than upon their chemical. It was believed, for example, that silica dioxide, or quartz, was particularly harmful because of its crystalline structure, and the hardness and sharpness of its particles. This concep tion is now known to be faulty. The dusts which cause their damage by mechanical in terference with function are the dusts which are relatively innocuous, whose symptoms are transitory, and which subside upon re moval from exposure to the dust. Chemical Effect la Harm ful The disease of particular interest to us today, silicosis, owes its harmful effects very largely to a harmful chemical reaction oc curring between silica dioxide and the body tissues. It. so happens that silica dioxide is decidedly a tissue irritant to the body, re gardless of the part of the body it invades, it causes local irritation, local destruction of tissue, and the replacement of that tissue by scars. Thus, given a dust containing silica diox ide in sufficient concentration, in sizes small enough to permit its entrance to the ultimate air spaces in the lungs, we have a situation which offers danger to the worker. -- We*1tKver 'a^s" W tTSe~ figures, but as a simple rule, we can adopt for practical purposes the thought that the human body can withstand successfully a concentration of dust containing ICO per cent silica dioxide in a particulate size less than 10 microns, in a concentration not in excess of 5,000,000 particles per cubic fo o t If we decrease the percentage o f silica dioxide present in the dust, we can correspondingly increase the concentration with comparative safety. We must, of course, take into ac count the portion of the worker's time spent in the dusty atmosphere. To arrive at a rough conception of a safe atmosphere, we multiply the percentage of free silica in a given dust by the total num ber of particles per cubic foot. If the result is under 5,000,000 the condition may be con sidered relatively safe. If the result is over 5,000,000 the condition must be regarded as unsafe. 'Bear in mind too that silicosis is essentially a disease of great chronicity. Except in a few exceptional instances it will require from seven to thirty years for a worker to develop advanced silicosis. It is evident too that coincident dusts may either retard the development of silicosis or hasten it. Recent research seems to indicate that the admix ture of aluminum dust to a silicious dust will greatly inhibit the reaction of the latter; whereas a silicious dust combined with some alkaline coincident dusts may hasten the de velopment of silicosis. Much research is now under way in prob lems such as this. We have never learned how to cure silicosis, but we are learning rapidly how to prevent it. Our knowledge in this respect seems to be limited to the removal of dust from the breathing zone of the worker. Later discoveries may show us how to modify existing dusts with contaminant dusts that will render silica dioxide innocu ous. Owing to its very great chronicity, it is only the rare case who actually develops disabling silicosis during his industrial life time. It is realized, of course, that excep tional instances take place, but the coincident ravages of age usually keep pace with the effects of dust, so that much n* the disability.usually attributed to silicosis is often, in fact, actually attributable to other dis eases or incapacities which advancing years bring in their wake. To me the great peril of silicosis, the peril not only to the industrial huiitftrial Dusts 97 worker himself, but his family, co-workers and the public generally, is the accompany ing susceptibility to tuberculosis. Complicated by Tuberculosis Silicosis per se does not kill. Tuberculosis as a complicating factor of silicosis rarely recovers, despite treatment, and the indi vidual so afflicted is not only totally dis abled himself, but a definite menace to all with whom he comes in contact, particularly the fellow worker who may have silicosis. So perhaps the most important places'in which the services of the physician in a dusty trade are necessary are--first, along lines of discovering and barring from exposure to a silicious dust those persons who may al ready have arrested tuberculosis; and sec ondly, discovering those persons already ex posed to dust, possibly already silicotic, in whom tuberculous infections may have de veloped. It is well recognized that no individual should be exposed to dust containing silica dioxide until he has undergone a thorough physical examination, including carefully made and interpreted x-ray films of his chest. It is likewise obvious to anyone fa miliar with silicosis that no person who is exposed to silicious dust should be denied the privilege of frequent physical examina tions and x-rays of the chest, not entirely to discover the existence of possible silicosis, but to discover a coincident tuberculosis if such exists. A man so diseased should, in protection to himself and to all with whom he comes in contact, be removed from industry. Let me emphasize the uselessness of a physical examination, unless it be accompanied by* properly taken x-ray films, except in cases of gross tuberculosis. It is the function of the physician, there fore, to conduct in a thorough and an intelli gent manner the pre-employment examina tion of all persons who are to be engaged in a dusty trade. The purpose of this ex amination should be threefold. First, to discover and bar from employment in dust, any person who is suffering from tuber culosis in an active, a quiescent or an ar rested state. A possible exception might be made in individuals suffering from a so called healed primary complex, or a healed childhood in fection. It is well known that exposure to silica dioxide is very likely to excite into activity a turbcrculous lesion which may be quiescent or arrested, and. once such a lesion is reactivated, the chances of recovery are remote. The second problem which confronts the physician at the pre-employment physical ex amination is whether a given individual is, by reason of secondary physical defects, more susceptible to the development of sili cosis than a normal. Is he suffering from diseases of the nose or upper respiratory tract, such as chronic sinusitis, disease of the lungs or air passages, or obstructions which produce mouth breathing? We must remember that silica dioxide is not dangerous until it reaches the lungs, and that the normal individual retains in the nose and the upper air passages a large quantity of the dust inhaled from the atmos phere. In instances where this nasal reten tion is disturbed, exposure to silica dioxide dust may be dangerous to that individual, Vshere it would not be to another. It is believed that certain diseases of the heart and circulation, of the kidneys, possi bly syphilis, chronic coincident diseases of the lungs, all may render a man more sus ceptible to silicosis than normal. The physi cian at his pre-employment examination must follow certain established criteria in this respect, and bar from exposure to dangerous dusts those persons who through existing disease may be more ready prey to silicosis or tuberculosis. Re-Examination Needed After the applicant for employment has successfully passed his physical examination and is engaged in a dusty trade, the duty of the physician is not yet ended. This work? man must be periodically re-examined, first to discover the early appearances of pul monary fibrosis, but what is even more im p o rta n t to detect the early evidences of complicating tuberculous infection. A man should not be dismissed from em ployment in a dusty trade merely because he has evidences of non-disabling silicosis. Workers in dusty trades, especially stone cutters, moulders, pottery workers, and similar craftsmen, are usually highly skilled, and it seems unfortunate from a social and economic point of view to deny them em ployment so long as they are physically able to carry on, especially since the actual dis abling qualities of silicosis are in doubt. ! ijfv 1 /' ' } tA K*'i' 98 Twenty-sixth National Safety Congress They should be denied employment in a dusty trade if that condition is found at <pre-employment examination, but they should not be barred from continuing an employment in which they are already en gaged. Of course, in such instances you, as engineers, must realize that yon have failed, because if you had kept the breathing zone of the worker free from dangerous dusts, silicosis would not be present on physical examination. In this work of preventing dust diseases in industry, it should be evident that the closest and most intelligent cooperation between the physician and the engineer is necessary. The physician must, through his knowledge and research, tell the engineer what dusts, or, for that matter, what other substances used in industry are harmful. He must tell the engineer how such dusts or other materials enter the body, how they leave the&ody and what they do in their passages through or their residence-in the body. Must Make Analyses The engineer must in turn tell the physi cian of the harmful dusts and other sub stances surrounding his .workers. He must make chemical and petrographic analyses of the dusts, and other indicated analyses of the atmosphere in the workshop. He must make dust counts and check his counts at regular intervals, conferring with the physician in an effort to discover whether, in the light of their joint knowledge, working conditions are dangerous. He must develop and install carefully designed ventilating equipment He must arrange for modification o f chemical and other industrial processes, where such modification is possible, and must (tend his efforts toward removing from the danger zone of the worker the offending substance, whatever it may be. Too many engineers construe this function loosely. They pass on to the physician as his responsibility certain functions which es sentially are theirs; such functions as dust analyses, dust counts, and similar technical duties. All too often it is considered ade quate merely to install a fan. Ventilating devices in dusty work rooms must be constructed only after careful en gineering study has given a knowledge of the physical properties of the air and of substances polluting it. It is possible to calculate to a very fine point the volume of air that must be removed from a given spot to remove the dust originating at that place, and the engineer must approach his task from just as scientific an angle as the physi cian approaches his. There is no room in industry for hap hazard methods on the part of either the physician or the engineer. ADJOURNMENT Public Utilities Section Officers 1936-37 General Chairman--J ohn J. Barada, The Laclede Gas Light Co., St. Louis, Mo. Vice-Chairman for Telephone and Telegraph Interests--W. P. E lstun, American Tele phone and Telegraph Co., New York, N. Y. Vice-Chairman for Gas Interests--E. P. D urfee, Consolidated Edison Co. of N. Y., Inc., New York, N. Y. Vice-Chairman fo r Electric Interests--Wit. H. B rown, Northern States Power Co., Min neapolis, Minn. Secretary--H. A. P tolemy, Public Service Co. of Northern Illinois, Chicago, 111. News Letter Committee-- D. C. D uncan, Chairman, Appalachian Electric Power Co., Bluefield, W. Va. P. L. G. H asskarl, Pennsylvania Power Co., Allentown, Pa. J akes D . H all, Atlantic City Electric Co., Atlantic City, N . J. E. R. K ropp, Union Electric Light and Power Co., St. Louis, Mo. E. S. L icht, New York State Electric & Gas Corp., Geneva, N. Y. D. E. W oods, Central Power & Light Co., Corpus Christi, Tex. Engineering Committee-- W. H. M ulligan, Chairman, Hydro-Electric Power Commission of Ontario, Toronto, Ont., Canada. A. A. K linge, Public Service Co. of Colorado, Denver, Colo. P aul R. K uhn, Penn Central Light & Power Co., Altoona, Pa. J ohn P. M cC ann, New England Power Assn., Boston, Mass. W. J. M cV ay, Consolidated Electric and Gas Co., New York, N. Y. , Health Committee Chairman--D r. H art E. F isher, Chicago Rapid Transit Co., Chicago, 111. Visual Education Committee Chairman--C. L. H ichtower, United Gas System, Houston, Texas. Publicity Committee Chairman--R. S. M etzger, The Toledo Edison Co., Toledo, Ohio. Membership Committee-- ' H. W. L ueck, (Chairman), Commonwealth Edison Co., Chicago, III. H arry B erman, Consolidated Gas & Electric Co., Baltimore, Md. M. T. Caster, Lincoln Telephone and Telegraph Co., Lincoln, Nebr. E. P. N oyes, Central Maine Power Co., Augusta, Maine. E. A. Rust, Erie County Electric Co., Erie, Pa. H. E. S hedd, Appalachian Electric Power Co., Bluefield, W. Va. R. Steele, Oklahoma Gas and Electric Company, Oklahoma City, Okla. P. K. Stiles, Compania Cubana de Electricidad, Habana, Cuba. Program Committee Chairman--C. H. Dinsmore, Wisconsin Power 8c Light Co., Madison, Wis. Statistics and Contest Committee Chairman-- Charles S. Bowden, Ohio Public Service Co., Alliance, Ohio. Special Representatives--W. A. B uchanan, Appalachian Electric Power Co., Welch, W. Va. (E. E. I.) Charles J. Gefvert, C hairm an, Accident Prevention Committee, American Gas Asso ciation. 537 J-fii li I lv || ili i*. it! it II! '[ i; 538 Twenty-sixth National S a fety Congress Councilors-- E. S. Beaumont, The Peoples Gas Light & Coke Co., Chicago, 111. C. B. Boulet, Wisconsin Public Service Corp., Milwaukee, Wis. G. A. D oeller, The Dayton Power & Light Co., Dayton, Ohio. J ames B. D ouglas, The Philadelphia Gas Works, Philadelphia, Pa. Roy M. Godwin, Philadelphia Electric Co., Philadelphia, Pa. E. J. K reh, Philadelphia Company, Pittsburgh, Pa. W ills M aclachlan, Electrical Engineer, Toronto, OnL, Canada. B, B. M cC ulloch, Bureau of Safety, Chicago, III. G eorge O pp, Detroit Edison Company, Detroit, Mich. ' F. M. P epper, Illinois Bell Telephone Co., Chicago, 111. C. J. R utland, Texas Power & Light Company, Dallas, Texas. C. B. S cott, Bureau of Safety, Chicago, 111. J. L. V andegrift, The Chesapeake and Potomac Telephone Co., Washington, D. C. H. F. W ebb, West Penn System, Pittsburgh, Pa. Officers Elected for 1937-38 General Chairman--W. P. E lstun, American Telephone & Telegraph Co., New York, N. Y. '- : Vice-Chairman--E. P. D urfee, Consolidated Edison Co. of N, Y., Inc., New York, N. Y. Secretary--H. A. P tolemy, Public Service Co. of Northern Illinois, Chicago, 111. Netvs Letter Committee-- D. C. D uncan, Chairman, Appalachian Electric Power Co., Bluefield, W. Va. H. H. B erman, Consolidated Gas, Electric Light & Power Co. of Baltimore, Balti more, Md. S. C. D ickinson, Pacific Gas & Electric Co., San Francisco, Calif. E. R. K ropp, Union Electric Company of Missouri, St. Louis, Mo. W. J. M cV ay, Stone & Webster Service Corp., New York, N. Y. P. K. Stiles, Compania Cubana de Jlectricidad, Maximo Gomez No. I Apartado 1715, Habana, Cuba. D. E. W oods, Central Power & Light Co., Corpus Christi, Texas. Program Committee Chairman--R. S. M etzger, Toledo Edison Co., Toledo, Ohio. . Publicity Committee Chairman--C. H. D insmore, Wisconsin Power & Light Co., Madison, Wis. Visual Education Committee-- H. W. L ueck, Chairman, Commonwealth Edison Co., Chicago, III. E. S. M iner, American Telephone & Telegraph Co., New York, N. Y. C. N. R akestraw, The Cleveland Electric Illuminating Co., Cleveland, Ohio. Engineering Committee-- , W. H. M ulligan, Chairman, Hydro-Electric Power Commission of Ontario, Toronto, 1 Ont, Canada. E. C. Bookman, Virginia Electric & Power Co., Richmond, Va. C. H.-D avis, Commonwealth Edison Co., Chicago, 111. J. D. H all, Atlantic City Electric Co., Atlantic City, N. J. P, L. G. H asskarl, Pennsylvania Power & Light Co., Allentown, Pa. P aul R. K uhn, Pennsylvania Edison Co., Altoona, Pa. Public Utilities Section S39 J. F. McCabe, Duquesne Light Co., Pittsburgh, Pa. John P. M cC ann, New England Power Service Co., Boston, M ass. ^1 1 1 ^ ^ omm^ lec ^ a*rmaM--D r, H art E. Fisher, Chicago Rapid Transit Co., Chicago, Membership Committee-- E. J. H anlon, Chairman, Peoples Gas Light & Coke Co., Chicago, 111. W. H. B rown, Northern States Power Co., Minneapolis, Minn. M. T. Caster, Lincoln Telephone and Tcelgraph Co., Lincoln, Nebr. R. A. E dwards, San Diego Consolidated Gas & Elec. Co., San Diego, Calif. A. A. Klinge, Public Service Co. of Colo., Denver, Colo. E S. Licht, New York State Electric & Gas Corp., Geneva, N. Y. C E M cB ride,' Northern Indiana Public Service Co., Fort Wayne, Ind. E. P. N oyes, Central Maine Power Co., Augusta, Maine. H. E. S hedd, Appalachian Electric Power Co., Bluefield, W . Va. J. R. S teele, Oklahoma Gas & Electric Co., Oklahoma City, Okla. Statistics and Contest Committee Chairman--Charles S. Bowden, Ohio Public Service Co., Alliance, Ohio. Councilors (Past General Chairmen)-- John J. B arada, The Laclede Gas Light O l , St. Louis, Mo. (1936-1937) E. S. B eaumont, The Peoples Gas Light & Coke Co., Chicago, 111. (1930-31) C. B. Boulet, Wisconsin Public Service Corp., Milwaukee, Wis, (1932-33) G. A. D oeller, Dayton Power & Light Co., Dayton, Ohio (1931-32) James B. D ouglas, The. Philadelphia Gas W orks Co., Philadelphia, Pa. (1916-17) Roy M. Godwin, Philadelphia Electric Co., Philadelphia, Pa. (1935-36) E J. K reh, Philadelphia Co., Pittsburgh, Pa. (1934-35) W ills M aclachan, Electrical Engineer, Toronto, O nt, Canada (1919-20) B. B. M cC ulloch, Bureau of Safety, 20 N. Wacker Drive., Chicago, III. (1925-26) George O pp, Detroit Edison Co., Detroit, Miph. (1926-27) F. M. P epper, Illinois Bell Telephone Co., Chicago, 111. (1933-34) C. J. R utland, Texas Power & Light Co., Dallas, Texas (1927-28) C. B. S cott, Bureau of Safety, 20 N. Wacher Drive, Chicago, 111. (1917-18) H. F. W ebb, West Penn System, Pittsburgh, Pa. (1928-29) Special Representatives-- i-3> C. J. Gefvert, Consolidated Edison Co. of N. Y., Inc., New York, N. Y. (A.G.A.) L. M. S hadgett, Georgia Power Co., Athens, Ga. (E.E.I.) TUESDAY AFTERNOON SESSION O ctober 12, 1937 The opening session was called to order St. Louis, Mo., who introduced the spekby John J. Barada, Laclede Gas Light Co., ers. iv.Hr 540 Twenty-sixth National Safety Congress What Are We Doing? By CHARLES B. SCOTT President, Bureau o f Safety, Chicago, 111. It would seem appropriate at this anni versary meeting of the National Safety Council to consider seriously what is being done in the work for which it stands and to measure the accomplishments of the past and look at the problems and objectives the future will bring. y No one can deny that the Council is largely responsible for initiating organized efforts for the prevention of public and industrial accidents and that it has been and is now recognized as the most effective agency in our country to stimulate iriterest, to correlate standards of procedure and to provide a forum of education so necessary in a cause which has .become of such im portance and of mutual interest to all citi zens. It has not been the privilege of many of those present to experience the conditions which brought about the safety movement nor to follow its successes and failures. Due to the nature of the cause fostered by the Council, its work has enlisted and has been dependent upon those who, without a selfish interest, were prompted to contribute to the welfare of society and to prevent a deplor able and useless waste of life and property. The Council has been kept alive and ac tive by the volunteer services of industry and citizenship, unselfish and earnest in their support. Whatever has been achieved has been made possible by such sincerity of purpose and freely given service. The com pensation has been accomplishment in a worthy cause, designed to help mankind. Pioneering at best is slow, difficult and with frequent discouragements, and the cause of safety during the past twenty-five years has proved to be no exception to the rule. It is particularly discouraging, after so many years of faithful work prompted by un selfish motives, to contemplate the toll of lives yet being sacrificed to carelessness. Unfortunately the measurement of suc cess in safety work is usually made by the comparisons of records of failures rather than by records of successful attainments. These become less dependable as a basis because they cannot take into account the constant materia! changes in hazards and risks brought about by the different condi tions which come into life and industry as a result of scientific advancement. Statistics of this year are of little value for compari son with the records of next year and cer tainly even less value ten years hence. As an example, if it were possible to compile automobile accident statistics on an accurate basis of the number of cars and passengers, mileage, conditions of roads and weather and numerous other factors including the provision for increased speed, then such records would serve as a comparison. How ever, .such accurate statistical information is impossible. Also, in the field of public utility, con struction, maintenance and operation, many changes are prevalent, making comparable records in accident prevention difficult and uncertain. If failures in prevention work cannot be accurately determined, how then can the successes be known without knowl edge of the lives saved or property sal vaged? If thoughtful consideration is given to the difference between the present life in public and in industry as compared with that of twenty-five years ago, and due weight is given to the hazards and exposure created within that period, then it is certain that the intensive efforts which have been made to conserve life and property and to prevent useless waste have not been in vain. From this logical point of view, the labors and expense of these years have more than been justified. The public utility industry has demon strated the value of safety work not only by the saving of life and limb but by the achievement of a more considerate manage ment, i an improved personnel, scientific application of safety measures to the im provement of equipment and mechanisms, improved employee relationships, and better and more courteous service to the public, i. Underlying the present day methods for the control of accidents are certain;essen tial fundamentals which have always been, and will continue to be, necessary of con sideration and whichj should constantly guide those who direct safety work. They are so well known that repetition would 542___ ____ Twenty-sixth National Safety Congress Such objectives should not only contcmpiatc the gradual improvement of records of accidents and the elimination o f tragic waste, but should also take into account the service being rendered to mankind for a ] better and happier life and for a citizenship 4 which will ultimately enjoy the fruits of present labors. Safety in Connection with Flood Emergencies as It Relates to Electric Operation By R. J. gALSBURY Superintendent of O perations, Duquesne L ight Co., P ittsb u rg h We ordinarily think of safety in the opera tion of an electric utility as a somewhat formal setup of rules and procedure to cover the operation of switches and the repair of machinery. We may begin to take it as a matter of course. Only when it is put to the test of a great emergency can we judge its real value. Such an opportunity was pre sented to the safety organization of the Duquesne Light Company, which serves the Greater Pittsburgh Area in Allegheny and Beaver Counties, Pennsylvania. The entire company met the greatest emergency in its history with no disabling injury during the anxious days and nights when its power plants and a number of its substations, trans mission and distribution lines were com pletely! out of commission and during the weeks of reconstruction which followed.. Pittsburgh experienced the most disas trous flood of its history on St. Patrick's Day, 1936. It came almost without warning and was four and one-half feet higher than the legendary flood of 1763. So far as the power system was concerned, we were pre pared for floods beyond any ever before ex perienced, but this one was so great that all of our power plants, one third of our sub stations, and many of our lines and cables were inundated, forcing us to shut down completely. For several hours we had no power whatever for a community of more than a million people. We had very little power for three days. Most of the city had no water. It had no street car or street lighting service. Food was stored in warehouses which, even when they were not flooded, had no elevator serv ice. Gasoline stations had plenty of gasoline in tanks under ground but they had no power to operate their pumps. Neighboring companies, even though seri ously crippled and with major problems of their own, extended such sources of power as werd still in operation. They curtailed the supply to some of their own customers so that as much as possible could be trans mitted to Pittsburgh. It was considered that the most essential service was communication, civic function such as water service, hospitals, dairies, and bakeries, followed by street services, news papers,' domestic lighting, commercial and industrial power. It is interesting to note that service was reestablished in the same order in the cities flooded along the Ohio River this year. The first available power was brought into the city in a novel manner. A 22 Kv inter connection was available at the southeast comer of the system. It was brought into the McKeesport Substation, then to Dravosburg Substation where it was stepped up to 66,000 volts. All the normal load switches along the way were opened so that no power was taken from the line, not even for lights at the substations. From Dravosburg it went to Woodville Substation, where it wa3 again stepped down to 22,000 volts to Chess Sub station, where it stepped down to 11,000 volts, to Grant Substation and then to the Main Telephone Building to be used for the batteries and the telephone system. Meanwhile from the westerly side of the system a 66 Kv line was available except that it had a tap to the Ambridge Substation where the oil breaker was under water. To open it, the operators had to cross a creek which was then 200 feet wide. When a boat was finally obtained, it was necessary to detour it in a truck for 15 miles over coun try roads. The men had to maneuver the boat around the switches, transformers, and steel structures, to get to the breaker. They