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FILE NAME: National Safety Council (NSC) DATE: 1937 DOC#: NSC135 DOCUMENT DESCRIPTION: NSC Health Practices Pamphlet - Silicosis ...... -...... M11COS1 Health Practices Pamphlet No. 20 Published by National Safety Council 20 North Wacker Drive, Chicago JL^K> 1. During the past few years so many conflicting statements have been made about silicosis that many persons have become confused. Alarmed work ers have filed claims against their em ployers, sometimes unjustly. In some cases apprehensive employers have es tablished labor policies that have re acted unfavorably against both them This pamphlet presents a sum mary of the outstanding facts and suggestions contained in the reports of the National Silicosis Conference, organized and con summated by the U. S. Depart ment of Labor, Washington, D. C. selves and the workers. A few incom petent attorneys and physicians, par dusts that are harmful to workers under ticularly in court cases, have further certain conditions, but the Conference complicated the situation. confined its deliberations to a discus 2. To aid in bringing order out of ^ chaos, the Secretary of U. S. Depart ment of Labor on April 14, 1936, called sion of silica dust. Thus this pamphlet, too, is limited to a discussion of silica dust. the First National Silicosis Conference. What Is Silicosis? It was attended by more than 300 per sons representing workers, employers, state and federal agencies, insurance companies and other interested groups. Four committees were organized: 1. Committee on Prevention of Sil icosis through Medical Control. 2. Committee on the Prevention of Silicosis through Engineering Con trol. 3. Committee on the Economic, Legal 4. Silicosis may be defined as "a chronic disease due to the breathing of air containing silica (Si02), character ized anatomically by generalized fibrotic changes and the development of miliary nodulation in both lungs, and clinically by shortness of breath, decreased chest expansion, lessened capacity for work, absence of fever, increased susceptibility to tuberculosis (some or all of which and Insurance Phases of the Sili may be prevented), and by character cosis Problem. istic roentgenological findings." 4. Committee on the Regulatory and Administrative Phases of the Sil 5. In other words, silicosis is a dis icosis Problem. ease of the lungs in which the normal 3. The reports of these committeleusng tissue is replaced by fibrous or were completed and considered by the scar tissue due to breathing air con Second National Silicosis Conference, taining high concentrations of silica February 3, 1937. This pamphlet pre dust. sents a summary of the outstanding 6. Unfortunately there is no known facts and suggestions contained in the cure for silicosis-- but silicosis can be reports, although much of the discussion prevented. concerning the insurance and legal phases of the subject has been ignored ^ because it is comparatively unimportant to engineering and medical technicians, How Many Workers Have Silicosis ? There are, of course, numerous other 7. No one knows how many work- C op yright, J9-17, N atio n al S afety C ouncil, Inc. ers have silicosis. Most of the surveys made in this and other countries have been confined to the mining industry. From these reports, and from other available data, a number of estimates have been advanced on which there is rather general agreement. 8. It is estimated that of the 49,000,000 workers in the United States, only 1,000,000 (2 per cent) are in any way exposed to the hazard of silicosis. Perhaps half of this number, 500.000 (1 per cent of the total), are exposed to a serious hazard. Approx imately 110,000 (2/10 of 1 per cent of the total) have silicosis in some degree. But it is likely that the number of per sons at work who suffer any disability from this disease is on the order of 4.000 to 5,000. This is approximately 1/100 of 1 per cent of the total. 9. From a purely statistical point of view, the problem of silicosis is not nearly so serious or so general as some other industrial problems, such as lead poisoning and industrial accidents. What About the Workers W ho Have Silicosis? 10. In answering this question, per haps it would be well to consider four groups of workers as already suggested: a. A percentage of the 4,000 to 5,000 workers who are completely or par tially disabled because of silicosis ant! whose difficulties are further com plicated with tuberculosis. b. The remainder of the 4,000 to 5,000 who have silicosis and some degree of disability, but no tuberculosis. c. The 105,000 who have silicosis, but no disability and no tuberculosis. (1. The 900,000 who are exposed to silica dust, but who do not have silicosis. PfcStiZl ^^PLA IN TIFFS h EXHIBIT Z HEALTH PRACTICES PAMPHLET NO. 20 11. Group A. From the standpoint of these men in Group A, the problem is a serious one, and there seems to be no doubt in anyone's, mind that these workers should be removed from em ployment and compensated for total disability just as if they had been in capacitated by accidental injury. 12. Group B. The remainder of the 4.000 to 5,000 workers who have sili cosis and disability in some degree, but have no tuberculosis, should in the ma jority of cases continue to work. While a few persons may be of the opinion that such workers are doomed to an early death, every study conducted thus far confirms the fact that the great majority of these men will not neces sarily progress from bad to worse. Per haps it may be wise to transfer some workers to other employment, but many may be continued at their regular occu pations ij known methods are applied to control the dust and if special care is employed to prevent the development of tuberculosis, pneumonia and other lung complications. 13. Group C. To the 105,000 work ers who have silicosis, but no disability and no tuberculosis, the problem is not particularly serious. Certainly such men should be permitted to continue work at their regular occupations but, as al ready suggested, known methods of controlling dust should be applied and care should be used to prevent the de velopment of tuberculosis, pneumonia, and other lung complications. 14. Group D. For the benefit of the 900.000 workers who are exposed to silica dust but who do not have silicosis, all emphasis again should be placed upon the application of known methods of controlling dust. Where D o Workers Contract Silicosis? 15. Silica dust is found in many in dustrial operations, but the hazard is acute only in such industries as metal mining; anthracite coal mining; quar rying, drilling, and tunneling in granite, ganister, and sandstone; smelting and refining of metals; foundries; potteries; glassworks; stone products; grinding; buffing; sandblasting. Under What Conditions Is Silica Dust Hazardous? 16. It should not be assumed, how ever, that all establishments in these in sputum. And' in addition to these data, dustries are hazardous. To tell whether ' the physician should also consider the or not a certain operation is hazardous, man's environment; th at is, he should it is necessary to determine at least know the number of years he has been three things: exposed to silica dust, as well as the dust count, composition, and particle a. The concentration of dust in the air-- size. number of dust particles per cu. ft. of b. The chemical composition of the dust --percentage of free silica. c. The size of the silica dust particles-- measured in microns. (A micron is approximately 1/25,000 of an inch.) 17. But even when these determina tions are made, it frequently is difficult to say that one operation is hazardous or that another is not hazardous. While it has been proved that particles larger than 10 microns in their greatest dimen sion are not hazardous, the factors of safety with respect to concentration and composition are not so definite. 18. In general, dust concentrations of less than 5 million particles per cu. ft. of air are at the present time consid ered safe even in cases where the dust contains a high percentage of free silica. To secure a more definite correlation of these two factors, it has been suggested that the dust count be multiplied by the percentage of free silica; then if the result is under 5 million, one can be almost sure that the conditions are safe. But the reverse is not so definite. If the result is more than 5 million, one can not say with assurance that the condi tions are unsafe. , 19. For example, 10 per cent (of free silica) times 30 million (particles per cu. ft. of air) equals 3 million-- safe. 20. But 30 per cent of free silica times a concentration of 50 million par ticles per cu. ft. of air is 15 million -- perhaps not as safe as the preceding example, but present knowledge does not warrant a statement branding this unqualifiedly as a hazardous condition. How Can You Tell Whether or N ot a Man Has Silicosis? 21. Physicians who .are most famil iar with the subject agree that this question can be answered only by tak ing into consideration the man's past occupational and medical history, his present complaints, a careful physical examination .and X-ray of his chest, and a laboratory examination of his How Long Does It Take to Develop Silicosis? 22. Contrary to popular belief, sili cosis is slow to develop. Usually it takes seven years or more of exposure to silica dust for a worker to contract the disease. It is said th at a few cases have been known to develop in as short a period as ly i years, but these were under extreme and unusual conditions. On the other hand, many workers have labored under ordinary conditions for more than 30 years without demonstrat ing any trouble that could be diagnosed as silicosis. Can Silicosis Be Prevented? 23. Although there is no known cure for silicosis, there no longer is any doubt that silicosis can be prevented. How Can Silicosis Be Prevented? 24. In general, there are three ways to prevent silicosis: first, by preventing the creation of silica dust; second, by preventing the dispersion of dust into the atmosphere of the working area; and third, if it is impracticable to apply the first two methods, by the use of approved personal protective equip ment, such as respirators, to prevent the inhalation of dust. W ho Can Prevent Silicosis? 25. There are many agencies that must cooperate if silicosis is to be pre vented. Certainly the employer is called on to do most of the work and to spend most of the money. But his work and money will never accomplish the max imum results unless the worker is will ing to cooperate and carry his share of the responsibility for helping to con trol dust and for using the personal protective equipment. 26. In addition, physicians can pla., a definite part in preventing silicosis, as can engineers, insurance companies, legislators, administrators and others. SILICOSIS 3 W hat Can the Employer D to Prevent Silicosis? 27. The reports of two Conference Committees on "Engineering Control" anti "Medical Control" discuss the an swers to this question in elaborate de tail and should of course be used for reference purposes. Nevertheless, this summary would be incomplete if it did not list at least a few things the em ployer should consider when formulat ing his silicosis-prevention program. 28. Survey the Working Conditions. Any employer who has reason to be lieve that his workers are exposed to the hazard of breathing silica dust should make a survey of the working conditions. This will enable him to de termine the severity of the hazard and will possibly indicate what, if anything, needs to be done to decrease the hazard. Assistance in making this survey, in making dust counts, and in handling some other details can be obtained from bureaus of industrial hygiene now es tablished in most industrial states, in surance companies, state labor depart ments, U. S. Bureau of Mines, U. S. Public Health Service, U. S. Depart ment of Labor, and other agencies. 29. Secure information on best procedure. Before formulating a pro gram for decreasing the silicosis hazard, the employer should secure the best in formation obtainable. Usually he can secure valuable data from the leaders in his industry, perhaps from the codes prepared by certain industries, and from other agencies such as those enumerated in Paragraph 28. It is surprising how often effective results can be secured at little cost through the installation of mechanical equipment. 30. Comply with laws, rules and regulations. It should be borne in mind, of course, that the employer must com ply with th laws, rules, and regulations that apply to his operations. Such re quirements, however, are "minimum not maximum requirements." 31. Design plant for dust control. Much can be accomplished through design when new buildings are contem plated or when old buildings are to be remodeled. For instance, structural projections and ledges may be min imized to prevent the accumulation of dust that might later be released into the atmosphere by air currents or by building""vibralionT'"'Buirding.. inteno'rs should be so constructed that they may be easily cleaned by washing, hosing, vacuum cleaning or brushing. In some cases operations may be located over gratings beneath which equipment is provided for removing the materials and dust that fall through. 32. Provide building ventilation. Special facilities for natural or median- ical ventilation are frequently provided and sometimes serve their purpose in helping to eliminate dust. Usually, however, such methods cannot be relied upon to provide complete protection industy operations. 33. Store dusty materials in dusttight bins. Dusty materials should be stored in dust-tight bins, tanks, or en closures, but each structure of this type should be provided with a breather or vent stack--perhaps with an exhaust fan in the stack -- to permit the air displaced during loading to be carried outside the building. Basements may be used for storage purposes but should not be used for dusty manufacturing operations. 34. Enclose material-handling equip ment. Excessive dust that is created by material - handling equipment can usu ally be confined by housing, and re moved by an exhaust system. Some materials can be kept in a moist condi tion while being handled, but when this is done, the material may dry out and be dispersed into the atmosphere as dust. 35. Isolate dusty processes. Where possible, several or all dusty processes may be isolated from the rest of the plant. This sometimes permits the in stallation of a more compact exhaust system resulting in more efficient opera tion and lower maintenance cost. 36. Provide wet methods of opera tion. Water, oil, and other liquids may be used to control dust: a. To suppress dust at the point or origin in such operations as rock drilling; handling, pulverizing,, and milling rock and ore; grinding metal on grindstones; abrasive-wheel cut ting of granite and sandstone. b. To prevent the re-dispersion of dust that has settled on the floors, walls, and other surfaces such as in the granite industry and in foundries. 37. Design equipment to control dust. When new machinery or other equipment is 'contemplated',' the' manu facturer can frequently be encouraged to include dust control features, such as exhaust hoods, as an integral part of the design and construction. 38. Provide exhaust systems. In some operations exhaust systems may be installed to remove dust at its point of origin. The technicalities of this sub ject are discussed in the Conference Committee reports which should be re ferred to for detailed data. (See also N. S. C. Safe Practices Pamphlet No. 32, "Exhaust Systems" as well as American Standards Association report, "Fundamentals Relating to the Design and Operation of Exhaust Systems." 39. Establish maintenance and good housekeeping procedure. Good house keeping is unquestionably the cheapest single method of controlling dust. Maintenance goes with it hand in hand. The best equipment in the world will not control dust if superintendents, foremen and workers are careless and' disorderly ip their wprk. Eight sugges tions are advanced by the Conference Committees: a. If dust-tight equipment is installed, it should be inspected -at regular and frequent intervals and all defects should be corrected as soon as they are detected. b. Operations should be performed in a manner that will create the minimum amount of dust, c. Use water under pressure where pos sible to clean building interiors. d. If practicable, combine water with air for cleaning purposes. e. Vacuum cleaning removes dust with out dispersing it elsewhere. f. Brushing is particularly adaptable for cleaning buildings of the older type of construction. g. Low-pressure steam can sometimes be used to advantage. h. A responsible person should be as signed the task of supervising main tenance and housekeeping activities. Among other things he should make tests from time to time to make sure that the program of dust control is achieving the desired 'results. 40. Provide respirators. The Con ference Committees agree unqualifiedly that dust elimination, must be given primary consideration in solving the silicosis problem. Nevertheless, when known methods of elimination are im practicable, there is still one more thing that can be done: that is, provide respirators so that the workers will not 4 HEALTH PRACTICES PAMPHLET NO. 20 breathe dust into their lungs" It"is Im portant to note that respirators are rec ommended only as a last resort and for occasional exposure only. Rotation of personnel under these conditions is advisable. 41. There are two general types of respirators that are suitable for protec tion against silica dust: a. Air-jnirjfying respirators that filter out the dust particles. b. Supplied-air respirators in which dustfree air breathed by the worker comes to him from an uncontaminated out side source. 42. Most respirator manufacturers have submitted their devices for testing and approval by the U. S. Bureau of Mines. Lists of such devices can be secured'By..writing'"15"'Bhe''Eife" at Washington, D. C. 43. To maintain their effectiveness, a regular procedure should be estab lished for cleaning, sterilizing, and re pairing all respirators. The Conference Committees also present numerous sug gestions for obtaining the cooperation of workers in wearing and maintaining respirators. 44. Instruct the workers. Giving the workers proper instructions is an other duty of the employer. A great deal can be accomplished through the use of posters; by distributing pam phlets, pay-envelope enclosures, and other literature. As in accident preven tion, the foreman is the key man--his full cooperation is essential. What Can the Worker Do? 45. There can be no disagreernenf~S|jita about the desirability and necessity the cooperation of workers if the hazard of silicosis is to be reduced to the min imum. The worker should realize that the safe practices recommended and the equipment provided are designed to prevent injury to himself and to his fellow workers. The equipment should be used as directed and every effort should be made to maintain it in good working order. Furthermore, the worker is frequently in a position to observe faulty equipment and unsafe practices, and he should make it a point to report all such conditions to his supervisor. , 6-37---M m