Document Exb8w0rgeoN6BjVED4zZo44Qn

(Page 1 of 12)j DUP 0825056 Health Practices Pamphlet Net. 4 Published by National Safety Council, Inc. 20 North Wacfcec Drive, Chicago 6 Industrial Dust 1. The literature on hazardous ef fects of dust is so extensive that no at tempt has been made here tc cover the subject ir. all of its ramifications, but to assemble only the- outstanding data oa several of its aspects. This pam phlet is intended for employers, plant safety engineers, personnel managers, and supervisors generally, The subject has been approached from the prevention angle, giving general information on oc cupational diseases caused by dust and on methods of control. Mo reference is made to the economic and legal aspects of dust diseases in industry and none of the uncommon dusts as, for instance, might be found in the pharmaceutical industry, are discussed. There is a short section on dust explosibility. ' Physiological Effects of Dus 2. The inhalation of dust may pro duce different types of reactions' in hu man beings; ' a. Pneumoconioses (silicosis end as&estosis) which result in specific lung pathologic 2a.Silicosis increases susceptibility to tuberculosis. b. The systemic reaction caused' by such toxic dusts as lead, radium,, man ganese, cadmium and mercury com pounds, when either breathed or swallowed or possibly absorbed through the skin. c. A transient disorder known as metal fume fever, from the inhalation of finely divided metallic dust or fume particles such as zinc oxide. ' <L A reaction, allergic in nature, caused by breathing organic dusts such as pollen, dour, certain pulverized woods. e. An, increase in bronchitis and. cither acute respiratory infections by breath ing inert, nan-fibrosis-prtxhtcmg dost such as coal, emery, limestone, marble. 3. In each of the above cases, the inhalation of dust can be the sole cause This pamphlet is otto of mote than ISO Sato Practices atid Health Practices Pamphlets. It is a compilation of experi ence in accident prevention rom maay sources. It should not be assumed* how* evtc, that it includes every acceptable procedure the field covered. It must not be confused with American Standard safety codes; federal laws; insurance re quirements; state laws, rules and regular cicoi; and municipal ordinances. Addi tional copies of ibis pamphlet are avail able. Member price, 35 cents each. Quan tify end nun-memhe? prices on request. `lung/' "dust" and "abnormal condi tion.'' The present generally accepted meaning of the word involves the con cept merely of "dusted lung." The kind of dust inhaled determines the type of injury noted in the lungs, However, there is one pathological process which underlies lung disease caused by dust, This consists of & fibrosis or a replace ment of the elastic tissue of the SUrtgs by an impervious scar tissue. of disability. With tie toxic dusts, trouble may result from swallowing or more rarely from skin absorption, as well as from inhalation. Inhalation, how ever, is by far the most important means of absorption of industrial dusts. 4. Irritation and ulceration of skin and mucous membranes may be caused by such dusts as lime arid chromium compounds. Pneumoconiosis 5. Zenker applied the name "pneumcaoconlosis" to the various changes in the lungs caused' by the inhalation of dust. The term has now been shortened to "pneumoconiosis." It represents three words from the Greek, which mean 6. Research tat pneumoconioses has been carried on in the'Nortb Americas continent more actively in the past decade than in any other period. The hysteria with regard to silicosis and other occupational diseases has now ' largely subsided, and the subject is be ing more carefully considered and more soberly judged. "Hie Problem 7. Modern manufacturing methods are, m many instances, creating consid erable dust. Much of this-dust is often released ra the immediate area where men or women are working, and this fact compels a practical solution of the problem. 8. The first step is the prevention of injury to health by dust is the control of Its concentration so that workers will not be exposed to injurious amounts, In order to obtain wide spread control of dust throughout industry, it h necessary that information be developed and dis seminated on the effect of various kinds and amounts of dust to which workers are exposed. Origin and Properties Physical 9. Dust is formed by reducing solid ' materials to small sizes. Processes like (Copyright, 1929,1929, tfatitnot Safety Council, he, Alt rig/sis-mten/ed. Printed its V. S. A.) DUP 0825057 Z--HJP.P.-4 WEALTH PRACTICES PAMPHLET NO. 4 Figure 2. Left: Operator in monumeoi shed using pneumatic banker, Neither dust tsayrol nor respirator h*s been pro vided. Right: The same operation with goggles and dust-control hood in use. grinding, crushing, blasting and drilling produce dust particles of sizes from the microscopic to the visible, their composi tion being the same as that of the patent materials if not altered chemically dur ing the subdivision. Frequently the percentage of some hard mineral such as quarts in the fine dust may be less than that in the parent material. Common examples are the mineral or inorganic dusts derived from the disintegration of rock and the organic dusts like wheal and Sour. L0. Smoke from burning carbonace ous fuels--coal, oil, wood, etc.--contabs droplets as well as dry particles, Tobacco, for instance, produces a wet smoke composed of minute tarry drop lets. The particle size of tobacco smoke is about 0.2 S microns, n. When a solid is broken into fineiy divided particles and released in the air, one of the important changes that take place is that the apace occupied by the broken materia! and also the sur face areas are increased many times from that of the original mass. For ex ample, if one cc. (.061 cu. in.) of quartz is crashed' into particles one cubic micron in size, there will be If?2 (1,000, 000,000,000 or one trillion) particles with total surface areas of six square meters (9300 sq. in.) as compared with six square centimeters (.930 sq. in.) for the original block. If we assume a dust concentration of 100 million particles to each cubic foot of air, the one cc. of material will occupy an air space of 10,000 cubic feet. thousandth of an inch) in their longest dimensions :a order to enter the inner recesses oi the lungs where the damage is caused. It was formerly believed that the hardness and sharpness of quartz particles were deciding factors in the injurious properties of dust, but this view has been generally disproved. (See paragraphs 20 and 29). Hay fever and other allergic types of disease from or ganic dusts or larger particle sizes can be caused by breathing particles into the nose and not having them reach the Sungs at all. Ragweed pollen is from 18 to 2S microns in diameter. IS. By comparison a healthy red blood cell is about 7.8 inches, asd a white ce3) up to about 16 microns. A person with normal eyes can 3ee an ob ject SC microns in diameter. However, the reflection of light from a shirty par ticle of quartz may be seen when the particle is as small as 20 microns is di ameter. It is to be realized, therefore, that individual dust particles small enough to reach lung tissue are essen tially invisible to the naked eye. 14. Fumes may result from any of several chemical 'or physico-chemical changes such as zinc oxide, formed -whan burning zinc vapors arise from molten brass, or lead occurring in the exhaust of a motor car burning gasoline contain ing tetra-ethyl lead. Chemical 15. The chemical and mineralogies! make-up of the dust arc the deciding factors m determining its Injurious properties.. It has bepn shown that sili con dioxide (free silica) in the form of quartz my produce a disabling fibrosis, whereas little or no fibrosis is produced by the equally hard and sharp cornered aluminum oxide (emery). . Classification of Dusts 16. The following classification of dusts, according to their physical char acteristics and physiological effects has been arranged by Dr. R. R. Sayers: ORCANIC DUSTS A. Non-Living Organic Dusts As liie name implies, these are com prised of non-viabk. particles which msy or may not be cither toxic or irritant, bet nevertheless have effect on the human organism. 1. Toxic or Irritant Duttf. These are organic dusts which produce un toward symptoms either systemic or lo cal Those producing local symptoms are described as irritants, while these producing general symptoms are termed toxic. A dust may be both toxic and Irri tant. " 2, Allergic. __ (See paragraph 59.) B. Living- Organic Dusts These dusts contain particles capable of reproduction or multiplication, such as bacteria and fungi. They are usually fonnd in low concentrations and asso ciated with non-living dusts in the air. 1, Bacteria. One of the most .im portant is the anthrax bacillus, which is found in the dusts from skins, furs, wool and grime! hrir, horns, hoofs, bones, etc. Diphtheria, tuberculosis, typhoid andother bacillus-produced diseases may result from exposure to infected dusts. Bacteriai-sensidzed dust can also be the causa of allergic diseases, as asthma, hay fever, eczema, migraine Headaches, etc. 2. fhtnjjv. Dusts containing parasitic fungi may cause annoyance and discom fort. Mould on straw, fray, grass, vege table debris i typical of this type of dnst. C. Inorganic Dusts These are of mineral origin not rerjniring- a living organism to produce Asm. Mirny dusts not classed as toxic come under this classification. Classified under inorganic are toxic and/or irritant, fibroris-produring end non-fibrosis-pr&ductag dusts- i, Toxii (hid/at Irritant. These are iuherer,tiy toxic when inhaled, ingested or otherwise absorbed. Among them arc the dusts from, heavy metals and their compounds, such as lead, mercury, arsenic, cadmium, zatc. 12. With, fche exception of such fi brous materia! as asbestos, the dust partides must be smaller than 10 microns (one micron equals' one twenty-fifth INDUSTRIAL DUST K.lMh-4--3 2. Fibrosis - Producing Dusts. The most important of these are the inor ganic, slightly soluble dusts, which cause fibrosis in the iungs, of which quarts is the outstanding example. ,2 Non-Fibrosis Producing Dusts. These are inert, and by themselves sel dom if ever cause fibrous tissue, but may he free in the tissues or be absorbed. Included are aluminum oxide, coal, corundum, emery, limestone, magnesite, marble, plaster psm, polish of rouge, etc. The Respiratory System Retention of Dust 17. In'the human respiratory sys tem, there are complicated moist pass ages, on the wails of which dust partides will stick. Also, the-nose contains hairs -which catch some dust. However, the respiratory system can become over loaded with dust, and when this hap pens, the dust catching mechanism functions poorly. 18. . C. E. Brown has estimated the average amount of dust a normal man will retain. Breathing at the rate of 20 respirations a minute, for example, he will inhale about 10 liters a minute and retain 60 per cent of the inspired dust t \ It is estimated xongMy that the retea- v. ? tion of common silica dust is about 50 per cent, but the way this dust may be divided between the upper and lower respiratory passages has not been clear ly defined. Drinker has observed in the case of metal fume fever that slow, deep breathmg,"po55ibly five or aft. breaths a minute, is much more likely to produce a fever than the normal rate of about 15 breaths a minute. This is supposed ly due to the higher retention of dust re sulting from, deep breathing. However, we cannot select by any known exami nation. the men best suited to dust ex posure, although some men show them selves obviously unfitted for dusty at mospheres- 19. The way in which dust particles are removed from the respiratory tract has been described by Dr. A. E. Barclay, British' specialist on X-ray. The bronchi or respiratory passages, are covered with a number of tiny, hairlike cilia or roi. crascopic whip lashes. These cilia make a last stroke in one direction and a slower return stroke, They cover the passages leading to the lungs, and all i \ keep in rime with .each other. This tends V--' to push any foreign particles of dust up ward in the direction in which the diia bend, so that the particles may be ex pectorated. Drat particles which reach the Inner recesses of the lungs are also removed by means of dust valves (phagocytes) which ingest the dust partides and carry them to a system of fine drainage canals called the lymphatics. Both the cells and their contents are transported through these canals to sed imentary reservoirs known as lymph nodes. Sizes of Panicles- 20. Microscopic dust particles are, of course, attracted by gravity, but be cause of the high resistance* of the air, the smaller dust particles settle out more slowly. The settling morion, cf a dust Figure 4. Ground silica dumped osta the aptoa of a conveyor. Note die en closed conveyor exhaust hood ana the use of *a approved respirator by the operator. particle through. st31 air wBl vary with the size and shape of the particle. 21. In order that dust particles be inhaled, they must be small enough to float about is the air or be carried by air currents. It has been .shown by research that dust particles must be smaller than 3 microns in diameter to cause silicosis. However, since all at mospheric dusts indude a majority of particles smaller than this size, the partide size distribution of dust ia the sir is of little significance. McCrae showed that ?G per cent of' the partides in sili fibers are the cause of the physical irri tation resulting in asbestosis. IS. The finer partides cf dust re main suspended m a still atmosphere for relatively tong periods of time. Their chances of being inhaled are, therefore, greatly increased. The smaller dust par ticles also travel farther away from their point of origin, and inasmuch as the larger partides settle out very quickly, the farther away from the dust source, ibe greater will be the percentage of smaller particles. cotic lungs were found to be less than 24. Neither upper nor lower size one micron and that the largest partides limits have been suggested for toxic sub did not exceed 10.5 microns in their stances, as lead, etc, It is the opinion greatest dimensions. Results since ob of Drinker and Hatch that so physio tained by other investigators have logical size limits exist fori these sub served to substantiate this comparative stances. ly early statement. ' 22. - Ixt silicotic lungs, dust particles Silicosis under 3 microns greatly outnumber those 25. Undoubtedly the most important of larger dimensions. Some- have be kind of lung disease caused by the in lieved that the human respiratory halation of dust is that which has been mechanism is responsible for this size named "silicosis." grading. It must be realized, however, that considerable sirs griding is done la Definition the air before the dust comes into con 26. Dr. Gardner's definition of sili tact with the respiratory organs. An cosis is as follows; "Silicosis is a chronic excess of snail partides may be found disease of the lungs resulting from pro in the lungs simply because smaller par- longed inhalation of fine particulate sil tides remain suspended longer and In ica. If is manifested anatomically by greater amounts, Partides above five formation of sharply defined fibrous microns will not remain floating to the nodules not over four to six mm, ha di air for any great length of time.' The ameter, which in most cases are uniform air cells of the lungs are large enough to ly distributed throughout ail portions of admit particles possibly up to 200 mi both lungs; and dinicaBy by a paucity crons in length. However, according to of symptoms and physical signs that Clark and Drinker, the most represen usually appear only in the late stages tative particle sire in the lungs of men, of the disease and by a tendency to be who have died of silicosis is one micron. come complicated by tuberculosis. In 22a, Fine asbestos dust particles have been shown to produce only the inert reaction on the tongs characteris some cases, nodulatkm is concentrated in certain parts of the lungs, in which cases symptoms may be marked." tics of other silicate dusts. It is, con 27. Toe International Silicosis Con sequently, bdteved that the asbestos ference is 1930 defined silicosis as a ssoszs&cina 4-~H.F-P.-4 Health practices pamphlet no. 4 "pathological condition of the lungs due to the inhalation of free silica (Si02)." Other authorities have given various definitions. That given by the American Public Health Association includes the statement that silicosis is "`a disease due to breathing air containing silica." Say ers and Jones at the Saranac Symposium on Silicosis in 1935 -stated that, "From the viewpoint of etiology, the harmfulaess 0/ a given dust containing free sil ica is directly influenced by the number of particles of free silica less than 10 microns in diameter that si contains." Factors of Influence 28. Silicosis becomes noticeable after widely differing periods of exposure to silica dust, apparently depending on; a. The amount of dust inhaled, h. The percentage of free silica con tained therein. t. The size frequency, or fineness of the particles inhaled. <i. The nature and source of such other substances (including! vapors and gases} as may be inhaled simultane ously or otherwise. c, The powers of resistance of She indivtdus.! concerned. f. The presence or absence of a compli cation. by an infective process, g. Tits prasiiice o complicating condi tions such as high temperatures or humidity, and unfavorable postures. Physiological Effects 29. In earlier years it was believed that the physiological action of quartz on the lungs was caused by the hardness of the material. In fact, ft was claimed that men who worked on sandstone were harmed, not only by the silica particles, but also by sharp bits of steel. These ideas were contradicted By Dr. L. U, Gardner, of Saranac Laboratory, who showed that silicon carbide and fused aluminum oxide, both of which are harder than quartz, had practically neg ative physiological effects whoa inhaled. Dr. Gardner also showed that dust from the diamond, the hardest substance known, was practically Inert when in haled. 30. Silicosis is considered in three separate stages by medical authorities: First Stage: The dsse&ss here pro duces no disability and does no apprecia ble harm. The affected man can carry on' 15? operations as well as ever. Second Stage: Respiration is affected. The victim may be bothered by labored breathing. Third Stage! Tills stage may develop foltowing the second stage ever, if the riciim has been removed from the dusty itr.'.osplicre. Here labored breathing be comes severe and the injured person is susceptible to pulmonary tuberculosis, frequently with fatal results. The work er is now far below normal, and a possi ble victim to respiratory diseases. 31. Silicosis may be detected by 30ray in each of the three stages. How ever, X-ray appearances alone are not sufficient for a diagnosis of silicosis. The complete 'occupational sad medical his tory cf the employee should be care fully evaluated and related to the X-ray findings before a conclusion is reached. Figure 5. Ac automatic bag loader han dling finely powdered silica, dose As effective iocaf exhaust syscem is in opec- stioc. 32. From most industrial experience the development of silicosis may not be anticipated short of five years. A few cases have been claimed to develop in as short a period as one and one-half years, but these ware under extreme and un usual conditions. There has been evi dence that alkaline materials, such as soap powder, accelerate the develop ment of silicosis, but this has not been substantiated in recent experience. 33. Silicosis Is a disease of which the victim may be unaware h the early stages. Its development is usually slow and unperceived. Inasmuch as silicosis cannot' be cured by any means yet known and si Its advanced stages is frequently complicated by tuberculosis or other infections, the importance of prevention is-apparent. Also, ha many industries, new developments have greatly increased the' dust output. In granite stone cutting, for instance, aad in rock drilling, dust production in creased tremendously with the introduc tion. of pneumatic tools. 34. Men with, early -first stage sili cosis, in the opinion of the Saranac Sili cosis Symposium, are not disabled and are not a menace to their fellow em ployees. The fact that barely percepti ble. X-ray change is visible is not grounds for assuming disability, since most persons over 40 show soma chest changes regardless of dust inhalation. Action o Silica on the lungs 35. The theory of the action of silica on the lungs is as follows: Where quartz dust is inhaled and is passed through the upper respiratory tract, It readies the terminal dr sacs of the lungs where the exchange of gases between the blood and air takes place. At this point, as the dust is a foreign matter, It is ingested by what are known as "scavenger" cells which cany It through the walls of the air sacs to the lymph drainage canals located outside the air sacs. This re sults In a rapid increase of tissue cells which narrows the lymphatic channel, hampering elimination, as it is along these canals that foreign substances are removed. Abo, when silica is being re moved, the particle may kill the scaven ger cell by which It is being transported, with the result that all dust particles are not removed from the lung- Instead, they may remain along the course of the drainage canal Apparently, these small particles of silica dust are toxic in this location and the tissue cells in the im mediate vicinity are altered and re placed by what is "known as1 sca r or fibrous tissue. The ultimate result is large- areas of tissue or King volumes in which capillary actios, is definitely re duced -- through which a normal ex change of gases between the blood and inhaled air cannot take place. 26. As the inhalation of silica con tinues, the amount of fibrous tissue will, of course, increase, with the ultimate re sult that the lungs wifi not readily oxy genate . sufficient blood for the body need. This produces a shortness of breads in the affected individual In pro portion to die amount of scar tissue in his lungs. Free Silica vs. Silicates , 37. With the exception of asbestosia, the silicate dusts have not been shown to cause a disabling lung condition such as is produced by free silica.. Experi ments conducted both'by causing ani mals to inhale dust over a long period of time and by injecting dust hi their peritoneal tissues have shown chat silt- U o CO 10 atXs G> O industrial dust H.t3 P -4---' cate duits are inert and do not cause the characteristic noduiation produced by silica, la addition. ta the experimentation, men who are exposed to silicate dusts containing no free silka have been x-rayed, and in a number of cases there has been opportunity for examination of their lungs. The nodular appearance an the x-ray and the actual nodules on the lungs, both of which are characteristic of silicosis, have not been found when exposure has been limited to si&^tes. Gardner has stated that evidence so far available indicate that, where & disabling lung condition is alleged to result from exposures to sili cate dusts (other than asbestos), theta is either an unsuspected presence of free silks in the dust, the victim has had a previous undisclosed exposure to free siica dust, or there has been inadequate interpretation of the x-ray. On the other hand, Dreeson et ai. have reported pneumoconiosis in workers exposed to high concentrations (150 million par ticles per cubic foot oi air) of clean washed mica. Greenbutg sad his eoworkers found fibrosis associated with such symptoms as dyspnea and chronic cough in 14.5% of 111 iremolite Me miners and millers. These men -were all employees of 10 gt more years -ex posure and the reported dust concentra tions are as high as 1500 million par ticles pa? cable foot of ait. In two mines in this area, Gardner had found quarts ranging from 12 to 20 per cent, hot in the mills, where all rock is mixed and crushed, the dust showed low quartz percentages both rift Gardner's studies and those of Orenburg. This subject of the passible action of silicate dust on the long tissue is.being further in vestigated, and any indications that certain silicate dusts may ht causing a disabling lung condition should be given thorough study before conclusions are reached. Mixed Puses . 3?a. Where free silica, is mixed with other dust, the greater the percentage of free silica, the less the dust exposure required to cause silicosis. Since some dusts such as gypsum lave an. inhibit ing effect, there is an increasing tend ency to evaluate the extent of the hazard presented by mixed dust on the basis of the individual dust exposure. Mote data are constantly being ac cumulated on the actual effects of vari ous types of mixed dusts. Askestosis 38. Asbestos is the only silicate at present recognized as causing pathology,- and even its reaction is definitely differ ent from that due to silica alone (Drink s'). Itsibebavio? is the exception to the rule that silicates are inert, at least in uninfected tissues. Asbestos, when in haled, produces fibrous tissues in the togs of .both men and animals. As bestos is made p of hydrated silicates of magnesium with variable amounts of iron. calcium, sodium, potassium, and aluminum replacing portions of the mag nesium, The property common to' fill of. this group is the fibrous structure. It has been shown that the presence of fibers of asbestos are necessary for the production of asbestosls and this fact, coupled with, the observation, that fine asbestos-dust is analogous la its inert reaction on the lungs to-that of other silicate dusts leads to the conclusion that asbestosfs is the result of physical irritation of the lung tissue and not of chemical action as in the case of sili cons. ' 30. Following a study by The United States Public Health Service of the asbestos textile.Industry, it has been recommended that the dust concentra tion be kept at less than S million par ticles per cubic foot of air if asbestosis Is to be avoided. Tire use of a standard based on the number of fine particles result from the use of dust determina tion technique developed for the study of silica dust exposures. Although fu ture research wiS undoubtedly setups standard based oa toe number of as bestos fibers in air, keeping the fine dust at less than the suggested standard will keep the concentration of injurious fibers wfthin safe limits. ' Infection 40, ' la the opinion of most investi gators, the factor of infection is most important, It has been observed in guinea pigs with chronic pneumonia that in an Infected area which developed before exposure to dust, the local branches of the lymphatic system were not so efficient as those in the rest of the lung. Silica inhaled Into tissue thus . damaged appeared to accumulate in un usual amounts. 41, Sine* men with silicosis are more susceptible to tuberculosis than are normal men, there is often an excessive Incidence of tuberculosis among such workers. Usually disability and death of a silicotic, when duo to pulmonary conditions, results from the complteating tubemslosis. For this reason, it Is especially important to have a re-ern- _ TJ g ^ g a> 6--K.P.P.-4 HEALTH PRACTICES PAMPHLET NO. pbyment and periodic x-ray program ried from IQ to 72 per cent depending monia, bronchitis and similar physical among workers exposed to silica dust. <m length of exposure and dust concen ailments. 42. Gardner states as follows: "At the present time the treatment of tubercofosij in siUcatlc sublets Is comparable to that for ordinary consumption SO years ago. 'Hie prospects are far from hopeless. Silicosis is gradually being brought under control The time is cot far distant when dangerous concentra tions of silica dust will no longer be per mitted in American industries. Periodic examinations of those already employed will detect new infections in persons now silicotic. Prompt institution of tration--the higher percentages of in cidence being found among workers ex posed more than 25 years to concentra tions greater than 300 trillion particles per cubic foot of air. 46. According to A. E. Russell,, the disability rate among zmthntits miners from respiratory tuberculosis Is about 49. Also, Dr. Greenburg reminds us that there is an important factor other than the one of environment, which is that of individual susceptibility. In vestigators have noticed that men work ing m the same plant, at the same task and to the same work place, frequently do not develop silicosis to the same de gree. It is passible Sot one worker o be an early victim, while the man work ing beside him remains comparatively free. This angle of the problem Indi cates a need for further research. treatment will eliminate most of the hopeless cases of stoco-rabercolosto. Preempleymant examinations will insure placement of men to positions that they esn fill without damage to their health." 50. It is well, nevertheless, to con sider all coal mining as involving a risk to some degree, depending upon the type of rock being drilled. While the hazard may not be as severe as to most metal Coal Mining mining operations, it is of importance at least because oi the number of work 43. Antbraco-silicosts is a tom used men concerned. for a form of pneumoconiosis commonly called "miners' asthma." According to Public Health Bulletin No. 221, "An- thtaco-Silkiosis Among Hard Coal Min ers,'' it is a chronic disease due to breatbiag air containing dust generated in the various processes involved to tuuxtog and preparing anthracite coal It is characterized anatomically by gen eralized fsbiolic changes throughout both lungs and with the presence of ex cessive amounts of carbonaceous and siliceous materials. "* figure 7. A method of receiving dust into trucks and auxiliary collecting equip ment 4*4 times the rate for general manufac turing-, Thepneumonia rate is Jess than one-third of general- manufacturing. Bronchitis, however, is a ratftert common complaint 4?, S. L. Cummins and S. F. Sj-atfdeu 51. The hazard of silicosis seems to bs practically absent to fee manufacture of cement. A recently completed survey of 2000 cement plant employees to all sections of the country by Dr. LeRoy U. Gardner and staff of the Saranac Laboratory for the Study of Tuberci losis, has failed to demonstrate that the inhalation of cement plant or quarry dust has a sigroficant 'effect on fee res piratory tract. Neither did it appear that men who had spent fear industrial lives in such atmospheres were unusu _ ' 44. Symptoms found in early stages conducted an examination- of a large ally susceptible to respiratory infection. are shortness of breath, cough, pain in number of coal miners' lungs to South The Incidence of influenza, disabling the chest, and possibly physical weak Wales. As a result, they made the aids and pneumoafa'was not high. No ness. In the advanced stages of the statement--"Coal Is retained to large cases of clinical tuberculosis were dis disease there is loss of weight and de amounts only when there is a really high covered, and the incidence of beafed or creased capacity for work, due partly to silica- content,1* They added, 'We be latent foci as revealed to the roentgeno pulmonary infection. lieve that to the absence of fee silica grams Is the same as that found to tbs 45. In studies conducted by the United States Public Health Service to Pennsylvania, no cases of anthracosflicosis were found to the controlled group of hard coal mining employees whose dust exposure averaged less than five million particles per cubic foot- of air. However, the prevalence of anrhraca-fflEcosis among the entire group of employees was found to be about 23 per cent. Among all except rock work ers, less than two per cent of the men were affected when the duration of em ployment was less than 15 years, regard less of the amount of dust to the air. Among rock wa-ktr?,, who were exposed to dust averaging 35 per cent free silica the prevalence of mthraco-silicosis va faefor, there would be, under modem mining conditions, no serious degree of anthracosi,?." . L. Collins ami J, C. Gilchrist have claimed that workers who have bad considerable exposure to trim ming coal stops where there Is practi cally no silica- exposure, but nevertheless a very heavy dust condition, showed some fibrosis -which, however, was not considered disabling. ' 48. A study of 2500 post-mortem examinations made to Pittsburgh hos pitals shows that city air which may contain an unusually large amount or coal dust may cause lungs to become darkly pigmented but yet produce no pathology of importance other than per haps a predisposition to colds, pneu genera! adult population; namely, 4.5 to 5 per cent. Dr. Gardner has stated: "Although tfa medics! examinuPom re veal no evidence of respiratory injury front cement plant dust, even after pe riods of long exposure, maximum con centrations in dusty areas should be re duced to 100 million particles per cubic foot (light field count, mpvsger techniqtte) as rapidly as economically feasi ble. High concentrations may not be dangerous, but they are not compatible with good housekeeping standards. *An exception to the general rule is 2 inilcsted by ike discovery of two cases g of non-c'micat dust reaction in this group of 2.0QO persons. These men had been exposed to quartz dust (usu- 5sj ally in the form of sandstone) used in g the manufacture of special cement. While possibly Inhibitory effects of isj INDUSTRIAL DUST H.F.PM--' other components of cement mill dust seem to have protected all other per sons similarly exposed, these isolated individuals apparently reacrcd because of abnormalities peculiar (o themselves. Although it is known that protective action becomes less effective 3s the relative amounts of silica In the dust increase, the limits of toleration have not been defined. Therefore, the limit tor silica particles lass than 10 microns in diameter at the breathing zona was arbitrarily set at five million particles per cubic foot of arras determined by the United States Public Keahh Serv ice standard light field count.'1 Toxic Duses Breathing vs. Swallowing 52. Generally, workers may be poi soned by toxic dusts much more quickly through inhaling them than by swallow ing them. Bust swallowed with food goes Into the stomach from which the major part 1 it is directly eliminated. Setae may be picked up in the blood cir culation and then moved on to the liver. The liver, however, is an effective filter and detoxifier, and it is only the poison that gets beyond this point that enters general circulation. On the other hand, dusts that reach the lungs can pass di rectly into the blood stream, to the heart and then to all parts of the body. 53. Alice Hamilton, in "Industrial Toxicology" (Macmillan Company) points out the distinction between the two wajrs in which poisonous dust can be taken into the body in the following paragraph---"A great deal of money has been wasted by well-meaning em ployers who sought to protect lead fur- Figure 8, Vjew m an iroo foundry show ing fastwh gittidcts wiifi exhaust hoods. nacemen, white lead grinders, etc., against poisoning, by providing hath and lunch rooms, clean overalls, mouth washes, and such, instead cf preventing the escape of lead into the air the men were obliged to breathe. Unfortunately this has sometimes been done under a physician's advice. It must never be forgotten that the great majority of in dustrial poisons eater die body with the inspired air and that while a workman eats only three times a day, he breathes 16 times a-minute during the eight or ten hours of the working day." 54. Numerous authorities give evi dence that there is far more danger of being poisoned by inhaling toxic dusts thap by eating them with food or taking them in liquids. But all precautions should be taken to prevent toxie dusts from entering or even coming into direct contact with the body. lead 55. The practical problem in con nection with lead poisoning Is the pre vention of serious lead exposure. The problem consists 0? two phases: one, the determination of the limits of safe ex posure, (see paragraph 68} and, two, the reduction of lead exposure below these limits. ' 56. We must recognize however that lead is a normal constituent of a living animal and that there is a level o( lead absorption which fa safe, Lead Intoxi cation and lead absorption can be pre vented by engineering methods. (See Health Practices Pamphlet No. 3 and Safety Instruction Card No, 116 oa this subject.) : Metal-Fume Fever 57. Metal-fume fever may be- one of the results of breathing dust from metal sources. This malady usually follows contact with a heavy concentration of magnesium oxide, copper oxide, load, zinc oxide, and possibly lead oxide and manganese dioxide. _S8. The symptoms arc chills fol lowed by a malaria-like fever which usu ally passes off within 24- hours, allowing the worker to return to Ms job on the following day. The Erst attack usually immunizes the victim so that attacks are not experienced consecutively. How ever, after a lay-off or an absence from contact with the dust, a further attack Is likely. Slow, deep breathing, accord ing to Drinker and Hatch, seems, to bring about the symptoms more quickly. FTgura 9. Dust <x>Ucctae units mounted 00 rhe roof. Allergic Diseases 59. Conditions arising from allergic disturbances of as occupational origin are coming more into prominence, from the compensation point of view. 60. Persons said to be allergic are those who are particularly susceptible to certain substances with which they come fit contact These substances may in clude foods, drugs, and vapors and dusts sf various kinds. A. wide variety of substances may, therefore, fee responsi ble for allergic reactions in. various In dividuals, which substances may haven effect on others or, Lu some cases, may even be of positive benefit. The types of reactions experienced by affected in dividuals to given substances may also vary greatly both in nature and In de gree. A single substance may, in one case,--cause intestinal disturbances, in another case develop asthmatic attacks, and in a thirdcase cause a skin eruption. Still another person may be affected in ah three ways. 6L Dusts of various kinds sometimes cause attacks of asthma. Asthma, may he suffered by stableman from exposure to horse dander and by furriers from exposure to fur dust. Other. persons cannot work nearanimals or, in fact, keep pets or sleep on feather pillows without suffering acute attacks. Hay fever is another type of reaction to dust on the part sf certain Individuals. These dusts are frequently in the nature of pollen, as from plants. Hay fever, it is claimed, however, may also be caused by- other types of dust. In any event, the q precise manner in which an allergic in- C dividual may react to a substance to 13 wfalbh he has become sensitized cannot be predicted. ' to .o 62. Many believe that allergic la- cn (Uvidcsh are boro with their particular w 8--H.P.P.-4 HEALTH PRACTICES PAMPHLET NO. 4 be told that the maintenance of certain degrees of air cleanliness represents the best known practice. Moreover, while such standards would undoubtedly be of value for a single industry, under differ ent conditions and in other industries there would be a question of their Appli cability. 65. As the result of many years of practical experience in dust control in the South African gold mines, a concert oration of one mg. of dust per cubic meter of air was accepted as standard and is now know commonly as "the South African standard," In 1534, L. G. Irvine stated that no. miner who had entered the industry since this low con centration had been maintained had, as yet, contracted silicosis, 65. It was stated by D. E. Cum mings in a paper presentee! at the Second Symposium on Silicosis at Sar anac Lake-- . ", . . Information from field studies made in many parts of the world indi cated that a norma! man might work in pure crystalline silica dust for many years without Impairing Ids health it the concentration did not exceed five million particles per cubic foot of air.1' Kgwre 10. Portable industrial vacuum cleaner. types of hyper-sensitivity. While this b probably so, according to'Dr. May ti Mayors, individuals do not become sen sitive to substances which later cause tire trouble until they have had sufficient contact to become sensitized. When a person who Is hypersensitive first comas in contact with the substance, he is oat aware of fab condition. An "incubation period'' is required,'during which time repeated contacts perhaps sensitize him to a point where subsequent contacts may result in immediate allergic reac tion. TMs waiting period may vary from a week or two to several months or even years, However, the allergic tendency must have been in tits indi vidual to, begin with, and then there must be continuous or intermittent con- iact with the substance in question in order-tfaat the latent allergic tendency can be brought out. , 63. It bas been claimed that once a, person has become sensitized to a given substance, be may, more readily than before, become sensitive to other sub stances. Occasiooally, too, it has been suggested certain individuals are capable of developing a certain degree of im munity as time goes on. However, from the viewpoint of prevention, it seems logical that workingmen who have be come allergic to certain substances in the course of tier occupations should be encouraged to go into other lines of work, for in most cases the tendency is to become more sensitive as exposure continues. Permissible Dustiness 64. Generally, we lack, data for de fining rigidly permissible dustiness. The point has not been reached where a man ufacturer can be told the exact concen trations at which, for instance, bis men will start developing cases of silicosis, asbestosis, or lead poisoning. Ho can only 67. Dr. L, U. Gardner states, con cerning the permissible dustiness where silica is present: 'The evidence now available makes it seem improbable that a silica hazard is defined solely by the number and size ST the silica particles in industrial atmospheres. The other components of a dust-modify its action. Some may . inhibit, others retard, and perhaps some wilt be found to prevent its .in jurious effect. Because there possibil ities are recognized, it becomes diffi cult to set up definite standards of per missible dustiness in industrial atmos pheres. . . ` Dr. Gardner costumes further: "Mot enough 5$ known about the ac tion ofprctector substances to warrant the recommendation that they be em ployed to prevent silicosis hi industry. Our aim should be to reduce existing dust concentrations rather than to in crease them by adding more dust. I would very strongly oppose the recom mendation tbat protector dust be used to attempt fa prevent silicosis at the present tune. Bet I do believe that \vc should attempt to discover more about their action. Some, like gypsum, seem to combine with silica in the atmos phere, forming clumps which are too Heavy to remain suspended hi air and loo large to pass the barriers of Che nose and upper respiratory tracts. With sach. information at band, it may be (Page 10 of 12) INDUSTRIAL DUST H.P.P.-4~.y possible to apply the knowledffc in a practical manner" Manganese: 50 me- per cubic meter is safe (Drinker & Hitch). 68. Other threshold limits for spe cific dusts have been stated as follows: Asbestos--(Dreessen, et af. United States Public Health Service) 5ve mil lion particles per eu. ft.' Coal dust--(R. ft. Sayers* ah) 50,* OOO.OCX) particles per cubic fool for coal dust containing not over S% quartz, 10,000,000 to IS,000,000 panicles for dust with' 1.1% quarts, and 5,000,000 to 10, 000,000 particles tor hard rock. workers exposed to dust containing- .15% free siftes. Lead--(Legge and Puckering) more than ,S fng. pci- cubic meter is hazar dous anti (A. E. Russell et ah), less than .15 mg, per cubic meter is safe. Zinc oxtdc--CP. Drinker, at ah) 24 mgs. of ainc oxide per cubic meter for 8 hours of exposure or 45 mgs. for short exposures. 69. Of the metals, the following suggestions have been made: The American Public Health Associa tion Committee on Lead Poisoning state in their comprehensive 1945 Report that "when ihn iMr of workrooms regularly contains more than 1.5 milligrams of lead per 10 cubic meters of air, cases of dis abling (tad intoxication do not occur among men whe work regularly in such workrooms, and cases of questionable or minor intoxication are rare, lit practice the attempt is madtt to maintain the lead content of rite air within such limits as will yield an average of not more than l.S milligrams of lead per 10 cubic meters throughout the working day, while pre venting the 'occurrence of materially higher concentrations (5 miUigrs.tr.* per 10 cubit meters or more) " Zmc Oxide: To avoid metal fume fever the concentration should be kept below 14 mg. per cubic meter for 8 hours' Exposure or 48 mg for short ex posures (P. Drinker et at ). CMouarrtceUsfys,eCEulrittnegaCnodmBplaunmy Figure 11, Exhaust system for removal of lead dust and fumes. Control of Dustiness 70. There are various ways in which dust diseases and annoyances nay be avoided*: 1. The avoidance of exposure furnishes {he first and most important defense against industrial disease. fobs should be performed in clean asr as far as possible. It is not necessary, however, to prohibit all exposure to a toxic substance, as the human sys tem. cart protect and clear, ae vtseff to a certain degree. 2. Exposure can be limited by reduc ing working hours where dust con centrations cannot be sufficiently re duced to constitute an otherwise safe condition. 3. Safe processes may sometimes be substituted for those of an unsafe nature. An example o_ this is the substitution of abrasive wheels made from synthetic abrasives con taining ito quartz, for wheels made from natural sandstone, which Is about 95 per cent quarto. . 4. The substitution of wet methods for original dry methods has ex erted considerable control over dusty atmospheres. Dry drilling' is the cause of considerable dustiness in mining, which may be greatly re duced. by wet drilling. This is also true in many construction and quarry jobs, 5. An effective method for preventing the escape of undesirable dust into the working atmosphere la the local exhaust hood ft should be placed close to the source of pollution, to be most effective. The air should be discharged through a dust col lector to prevent contamination of neighboring areas or return of the dust through open windows into the plant. 6. The routine recording of dusty con centrations is a v&hsable check on the existing exposure. Periodical counts of air samples are a great help io shewing whether or not , there is need for further control. 7. In some cases, the application of genera! rather than focal exhaust ventilation is desirable. There are instances where 'the source of pol luting,materials ts constantly chang ing position and local exhaust be comes difficult and impracticable. Here a general ventilating system may he the only answer. -The eight methods of nreveotton given here asrinee"UstrtyedCilaerkthsisadorDdreicr klaw,"ptotfWiutsstsffeias.ibMyetahLe National Medical Book Cotppauy, Inc., New ?ork, 2f. T. Figure 12, Courtesy. Kirk and Bhjsn Manufacturing Company Adjustable exhaust hoods for polishing wheels. 8. A final method of protection is the wearing of special protective equip ment by workers. This step is fre quently the last resort and is used only in an emergency or for jobs of short duration, bat it is never theless of considerable importance. (See American Standard Safety Code for the Protection of Heads, Eyes and Respiratory Organs.) 71. In many localities codes or or dinances for the control of dustiness are in effect tvhich should be investigated and followed fay employers seeking to improve working conditions. Local Exhaust Systems 11. Loral exhaust ventilation for the control of industrial dusts and fumes consists of four principal parts: a. Exhaust hoods b. Piping or ducts c. Air cleaning plant d. Source of suction , 73. While each of these parts should be designed and installed to perform its required function with respect to the system as a whole, the exhaust hood probably demands the most careful , de sign, inasmuch as the degree of control secured depends to a larger extent upon the shape and location of the hood--and the rate of air flew to it--than upon any other single factor. _ ?4. Hoods have to a considerable ex tent followed the design first employed in such industries as woodworking and metal grinding. However, as noted by Theodore Hatch, in recent years the in dustrial dust problem has assumed by* O gienic and economic aspects entirely be- C yond the limitations of those industries j* in. which (he production of dust has been ^ August 29, 2008 Making our World Safer Waters & Kraus 3219 McKinney Ave. Dallas, TX 75204 To Whom It May Concern: The attached records are kept and maintained in the regular course of business of the National Safety Council, and it is the regular course of business of the National Safety Council to keep and maintain the attached records. The attached photocopied material is an authentic reproduction of an original file copy of: industrial Dusts, Health Practices Pamphlet No.4, National Safety Council, 1929, 1939. Respectfully, Robert J. Marecek Manager, Library 1121 Spring Lake Drive Itasca, IL 60143-3201 630.285.1121 630.285.1315 fax www.nsc.org