Document V3OrQr9QDYvLxmR6vMMrxO4Jj

r The Work Environment of Insulating Workers J. LeROV BA.LZER and W. CLARK COOPER, M.D. Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California 94736 fgf With the cooperation of the asbestos workers' union and insulating contractors, a study is being made of the environmental exposures and the health of insulating workers in the western United States. Surveys have been made in a number of work situations, including small commercial building, major industrial construction and marine operations. Major emphasis has been on exposures to asbestos-containing materials, fiber glass, cork, plastics, and adhesives. Trends in product usage are presented, as well as illustrative dust counts, based on membrane filter and impinger samples, for various components of the insulator's job, e.g., prefabrication, applica tion, finishing, mixing and tearing out of old insulation. Mag 11 2009 13125AM introduction V\7T ORKERS IN THE insulating trade W make up an occupational group known to have exposures to asbestos that are varied and difficult to control. Tn recent years, in vestigators have shown that the relationship between asbestos minerals and human disease extends beyond a disabling pneumoconiosis produced in some workers. Evidence has ac cumulated that asbestos workers have a high er incidence than average of malignancies of the lungs, pleura, and peritoneum. Asbestosis in insulating workers has been reported in England by Ellman1 in 1934 and by Leathart and Sanderson5 in 1963; in the United States by Fleischer et aU in 1946, Pendergrass1 in 1958, Marr4 in 1958, and by SeiikofT et al.n in 1964; in Sweden by Ahlmark et al.T in I960; and in Finland by Ahiraan* in 1966. Seiikoff0 reported lung cancer deaths in insulating workers in New YorkNew jersey to be over six times expected; Thin investigation was supported by Research Grant OH* 00204, from the Public Health Service, U. S. Department of Health, Education and Welfare and received preliminary support from General Research Support Grant I-SOi-FR05441, Public Health Service, U. S. Department of Health* Education and Welfare. Thi> report was presented at the American Industrial Hygiene Association Conference ill Chicago, Illinois, on May 5* 3967. Dunn and Weir9 in 1965 reported a higher than expected incidence of lung cancer in California; and Keane and Zavon10 in 1966 in their descriptive report of the insulating trade in Cincinnati also described an excess of lung cancer. Because asbestos may be a widespread en vironmental contaminant and the established threshold limit may need re-examination, there is need lor a thorough appraisal of the work environment of the insulating worker. We are now in the process of doing a study of San Francisco area insulating workers in order to determine the incidence of pneumoconiosis and malignancies and make observations and measurements on the work environment. This report summarizes our preliminary environ mental findings on the materials used, meth ods of application, and dust and fiber con centrations. Background Information on Union Membership This study was made possible by the whole hearted cooperation of the International As sociation of Heat and Frost Insulators and Asbestos Workers (both from their national headquarters and from the officers of their various locals), and by insulating contractors, individually and through the Western Asso- 222 American Industrial Hygiene Association Journal 223 ciation of Insulating Contractors. There are approximately 1,800 insulating workers in the Western States, but this report is limited to workers within the jurisdiction of the San Francisco Local (No. 16) which encompasses Northern California and Northern Nevada. This local at present has approximately 500 members, 70% of whom have been in the trade more than 10 years and 42% for more than 20 years. The union's health and wel fare fund has sponsored a program of volun tary chest films for the past 10 years, and 80% of those eligible have participated. Re view of these films has shown that about 25% of the members have roentgenographic chan ges strongly supporting a diagnosis of asbestosis with an equal percentage having sug gestive changes.31 Most of the local union members work for one of the 20 or so insulating contractors in the area and travel from job to job with a specific firm. There is considerable shifting from contractor to contractor so that many men have worked for all of the major con tractors at some time during the past 20 or 25 years. Nevertheless, the trade is a stable one, arising out of a high wage rate and a rigid apprentice testing and training program. Men who qualify and pass through the ap prentice school program tend to stay in the trade for their working life. Insulating workers learn to do all the major jobs in their trade and usually will work at any job assigned by their union dis patcher. Some prefer to work in heavy con struction or on the waterfront. The major types of work in which men are engaged can be classified as: (I) commercial building, which involves the insulation of pipe and duct systems in office buildings, apartments, shopping centers, etc.; (2) heavy industrial building, which involves the insulation of turbines, boilers, pipes, duct systems, and processing equipment in power plants, fac tories, etc.; and (3) marine construction and repair, which involves insulating turbines, boilers, pipes, and duct systems in ships in both naval and private vessels. Local 16 does not have jurisdiction in U. S. Navy ship yards in the Bay Area, which have their own local unions; but many of the members have in the past been employed in the naval ship yards. The following is a breakdown of employ ment by types of construction of the 401 ac tive members working as of March 31, 1967: 100 of the workers were employed in com mercial building; 236 of the workers were employed in heavy industrial building; and 65 of the workers were employed in marine construction and repair. The majority are employed in the building trades. When there is an increased demand for ship construction and repair, there must be a shift of the union population. For example, during World War II, more than 1,800 insulating workers were employed in Bay Area shipyards, even though the local's membership was only 500 mem bers. This was due to "travelers" from other locals and a large number of workers from other trades given temporary permits to do insulating work during this peak period. However, the general picture is that there are few travelers, and the Local 16 membership handles most of the jobs in this area. Rota tion between employers tends to keep the local member working in this area for the duration of his working lifetime. Insularing Materials Used Our analysis of the insulating worker's en vironment indicates that they are predomi nantly working with calcium silicate and magnesium carbonate insulating material con taining asbestos fibers, fibrous glass mate rials, plastics, foam glass, cork, and adhesives: l. Materials Containing Asbestos-- 100% Amosite blankets 95% Amosite--5% filler 10-15% Mixed amosite and chrysotile --85% magnesia 10-15% Amosite--85% calcium sili cates 10-15% Mixed amosite and chrysotile --85% calcium silicates 10-15% Mixed amosite and chrysotile 85% calcined diatomaceous si lica 100% Chrysotile asbestos shorts for finishing (mud) 50% Asbestos shorts and 50% ce ment for finishing (mud) 224 May-]une, 1968 2. Materials Containing Fibrous Glass-- Monoblock--compressed glass and resin binder Rolls Prefabricates--pipe and duct covering Mineral wool High temperature insulation Finishing materials (muds) Mineral wool and cement 3. Plastics-- Polystyrenes--prefabricated product, powdered Polyurethanes--foam in places, prefab ricated products 4. Cork 100% cork blocks 5. Glass Flakes-- Foam glass Table I Estimated Percentage of Volume and Application Time by Types of Insulation Material in Use in the San Francisco Bay Area Type of Insulation Material Volume % of total Total: Asbestos Fibrous glas>. Other (cork, rubber, loam glass. polystyrenes, polyurethanes) 100 45 45 50 Application % of time 100 55 40 5 Table II Estimated Percentage of Current Use of Fibrous Glass and Asbestos Containing Materials by Major Types of Construction Typos of Construction Fibrous Insulation Materials Used Total Fibrous Glass Asbestos Commercial building 100%. Heavy industrial building 100 Marine construction and repair iOQ 70% 30 20 30% 70 80 Table III Characteristic Properties of Chrysolite and Amosite Properties Crystal structure Color Approximate diameter of smallest fibers If) Specific gravity Index of refraction Chrysolite Sheet silicate White 0.006-0.015 2.55 1.567-1.639 Amosite Chain silicate Ash-Grey 0.05-0.1 3.45 1.639-1.708 6. Adhesives Epoxy and solvent; asphalt base and solvent Wheat paste Silicones Magnesia Portland Cement Table I is an estimate of the products used by volume and the approximate times spent in applying them. This information was ob tained from the contractors, men in the trade, and from personal observation during the past year. This table shows that fibrous asbes tos and glass materials account for 90% of the materials applied. Table II presents the percentage of fibrous insulation materials used by the contractors in our area by major types of work area. These fibrous materials were of paramount interest to us in reconstructing the work-a-day en vironment of insulating workers. Physical and Chemical Properties of Fibrous Materials Asbestos Asbestos is a commercial term applied to a group of fibrous silicates. They include chrysotile and the amphibole minerals--crocidolite, amosite, anthophyllite, tremolite and actinolite. Chrysotile (hydrous magnesium sili cates) is the most important commercial as bestos mineral, presently accounting for about 90% of the world's asbestos production. It occurs only in serpentine (hydrous magne sium silicate minerals) rock formations. Am phibole type asbestos is found in five commer cially useful forms: crocidolite, amosite, anthophyllite, tremolite and actinolite. In the United States insulation industry, chrysotile (Canadian) and amosite (South African) are most often used in manufacturing insulation materials (Table III). A unique physical characteristic of asbestos is its ability to longitudinally subdivide into fibrils of molecular diameter. The fibrils are too small to be counted with ordinary light microscopic techniques, making it difficult to assess the true fiber exposure. From the literature and from manufactur ers and their representatives, we ascertained American Industrial Hygiene Association Journal 225 the approximate amounts and types of asbes tos fibers which are used locally in 14 differ ent asbestos insulating products, manufac tured by seven major producers of insulating materials in the United States. This infor mation is summarized in Table IV. We con firmed the stated types of asbestos fibers in seven of the materials by x-ray diffraction analysis using a Norelco X-ray unit equipped with a copper target and x-ray diffraction tube. The manufacturers of asbestos insulating materials use varying amounts and types of asbestos fibers in their products and may re brand their product for distribution by anoth er manufacturer. Contractors will also order specific types of asbestos insulation because of their thermal properties and not because of the type of asbestos fibers they contain. These practices on the part of manufacturers and contractors make it impossible to reconstruct a working population that has had a "pure" exposure to one type of asbestos fiber. It has been our practice, in environmental sampling, to record all the insulating materials being used in order to determine product accepta bility by the insulators and to determine if any one type of insulation material produces more free fibers. Fibrous Glass Fibrous glass consists of a mixture of silicon dioxide, oxides of aluminum, calcium magne sium, boron and other additives. In general, the fibers of most commercial insulating prod ucts have a mean diameter of 4 microns or greater. Although this paper will not directly consider fibrous glass exposures, we have been obtaining environmental data and will an alyze it later. In our laboratory, we have optically de termined the diameter in microns of various samples of fibrous glass insulating materials used in our area. The acoustical materials have the iargest diameter: H to 14 microns; the building and duct insulation: 4 to 7 microns; pipe covering: 4 to 6 microns; and the special high temperature material: 1 to 2 microns. It is evident from this data that it is not difficult to find glass fibers in the worker's environment that are of a respirable size. With the increased use of high temperature insulation and special fibrous glass insulation materials, we are likely to see more and more fibrous glass insulation materials with a mean diameter of respirable size. Environmental Data As was described in the previous section, the insulating worker works with and is ex posed to a myriad of materials and condi tions. Many times the materials he is exposed to result from the activities of other trades in the area. Obtaining a true time-weighted exposure under these conditions is impos sible. It would require hours of observation and sampling of each worker in order to even attempt to estimate the integrated dose. Exposures in most other industries are fairly constant by comparison, in that workers con tinue at the same job in generally the same area. However, the insulating worker is al ways in a changing environment; the work locations, his position, materials, humidity, temperature, ventilation, and any number of other things are in a continual state of flux, In an attempt to reduce this to some order, we have classified all the jobs per formed by the insulation worker into six major categories: (1) Prefabrication: ma terials are precut and shaped using hand or power saws either on the job or at the con tractor's shop (10% of his time). (2) Ap plication: materials are fitted, hammered, or carved, and attached to the surface by wiring or gluing (40% of his time). (3) Finishing: materials are coated with asbestos containing cements, resins, asbestos or cotton cloth, or petroleum based sealers (30% of his time). (4) Tearing out: removal of old or un usable materials in the process of insulating or reinsulating (10% of his time). (5) Mix- Table TV Percentage and Type of Asbestos in Insulating Products in Current Use Type of Asbestos Aniosite Amosite Amosite-ChryjotRe Chrysotile Chrysotile Percent by Weight Number of Products 10-15% 95-100 20-35 10-15 85-100 3 3 3 2 3 226 May-June, 1968 Table V Dust Concentrations Based on Impinger Samples by Job Classification Table VI Fiber Concentration Based on Membrane Filter Samples by Job Classification Job Classification Prefabricatton Application finishing Tearing out Mixing Central Number of Samples Mean 15 6.5 1? 3.5 f9t 2.6 5.2 6 9.1 9 1.4 rappel Median 4.8 2,5 2.4 5.1 8.4 1.4 Range 0.8-28.8 0.8-8.2 i.2-6.2 2.5-8.6 2.8-16.0 0.6-1.8 job Classification Prefabrication Application Finishing Tearing out Mixing General ,, Samples Mean 22 8.5 45 6.4 31 2.7 17 8.9 S') 2.b Ifi 4.8 Fibers/cc Median 8.4 1.4 0.8 4.9 1.4 0.8 Range 0.1-24.3 0.1-61.6 0,1-24.4 0.2-26.3 0.2-10.7 0.1-22.9 trig: mineral wool, asbestos, fibrous giass, and cements or glues are mixed separately or in combination in buckets or troughs (5c/c of his time). (6) General: cleaning up of old insulation, transporting of materials (5% of his time). The percentage figures indicating the amounts of time spent at each of the job classifications are, of course, variable and are only intended as rough guidelines. For the purpose of this paper, we will limit our discussion to the environmental data obtained during insulating operations when only asbestos containing materials were used. To compare our sampling data with the present threshold limit value (TLV) of 5 million particles per cubic foot, we have taken a number of midget impinger samples along with our other methods of sampling. The results of the impinger samples arc summarized in Table V and are either breath ing zone or general air samples of a particular insulation operation. AH the samples were, counted in accordance with the standard procedures prescribed by the American Con ference of Governmental Industrial Hygien ists and include both grains and fibers. It will be observed from Table V that we have three distinct areas--prefabrication, tearing out, and mixing--where the present TLV is exceeded. Because of our interest in the role that fibers play in the pathogenesis of asbestosis, we placed the major emphasis of our en vironmental sampling on obtaining fiber con centrations under various working conditions. The personal and general samples were col lected on Millipore Type AA Filters mounted in field monitor cases. Most of the samples were breathing zone samples worn by the workers for periods ranging from 30 minutes to 3 hours. Since it was easy to overload the filter with fibers during heavy dust periods and negate the countability of the sample, it was necessary to replace the field monitor cases several times during the sampling period. The fibers were counted by clear ing a wedge-shaped segment of the filter using a modified technique of the Uni ted States Public Health Service12 and sized by the length and diameter at 430x magni fication using phase contrast illumination; we will only refer to the total fiber counts in this paper, A fiber is defined as having an aspect ratio of 3:1 length to diameter. If Timbrell's criteria13 for respirable fibers (diameter smaller than 3.5 microns) was used, 98% 2% of the fibers we have counted would fall into this category. The fiber counts per cubic centimeter are given in Table VI by job classification. Discussion Our environmental observation in the in sulation trade confirmed our initial impres sion that the varied job assignments, con struction methods, and materials used in current work practices make it extremely difficult to reconstruct a time-weighted aver age exposure for the major hazardous dusts and chemicals. Reconstruction of past ex posures is impossible. Although materials in use have changed over the past 20 or 30 years, with an increas ing use of fibrous glass and a decreasing use of cork, the construction industry continues to demand asbestos-containing insulation ma terials. The insulation worker's exposure to asbestos fibers is not disappearing. It is also evident that contrary to most other United American Industrial Hygiene Association Journal 227 States industries where asbestos exposures oc cur, chrysotile asbestos has not yet supplanted the use of amosite asbestos in the manufac turing of insulation materials. Amosite ex posures are the most significant in the in sulating trade. The breathing-zone dust levels found in the dustiest operations observed were not as high as the incidence of pneumoconiosis may have led us to expect. Some sample areas exceeded the present threshold limit value (TLV) recommended by the ACGIH; however, these samples were not for extended periods of time. Although we attempted to sample the dustiest operations, the timeweighted averages for dust samples contain ing asbestos would probably not exceed the TLV in most situations, even on ships. This conforms to findings by Fleischer el al.J by Marr5 and by Leathart and Sanderson2 and to recently reported findings by Ferris14 who last year reported studies in the same ship yards earlier appraised by Fleischer.11 The present TLV for asbestos was recom mended by Dreessen et at.1* in 1938, after epidemiologic studies in textile mills using chrysotile asbestos. It was not intended for extrapolation to all forms of asbestos use under all circumstances of exposure. The proven occurrence of pneumoconiosis in in sulating workers exposed intermittently as described in this paper and by the authors previously cited suggests that the TLV for asbestos is too high. Our studies are, how ever, not yet complete enough to warrant a final conclusion. We cannot eliminate the possibility that other components of the in sulating materials may be synergistic. The incidence of pneumoconiosis in these work ers, the need for better environmental con trol measures, and medical surveillance will be the subjects of more detailed later reports. References 1. Ellman, P.: Pneumoconiosis: Part III. Pulmonary Asbesiosis, Brit. J. Radiol. 7: 281 (1934). 2. L&athast, G. L., and J. T. Sanderson: Some Observa tions on Asbesiosis. Ann. Occup. Hyg. 6; 65 (1953). 3. Fuascwe*. W. E.. F. J. Vjles, R. J. Glams, and P. Drinker: A Health Survey of Pipe Covering Operations in Constructing Naval Vessels. /, Induit. Hyg. Of Tox. 28: 9 (1946). 4. Pe.ycmor.ass, E. Silicosis and a Few of the Other Pneumoconioses. Amur. J. Roentgenol. Radium Therapy Nud. Med. 80: 1 (1958). 3. Mara, W. T.: Asbestos Exposure During Navai Vessel Overhaul. Amtr. Indnst. Hyg. Assoc. ]. 25: 264 (1964). 6. Seukoff. I. J., J. Churb, and E. C. Hammond: Asbes tos Exposure and Neoplasia. J.A.M.A. 188: 21 (1964). 7. Ahlmark, Axel,, T. Bruce, and A. Nystrom: Silicosis and Other Pneumoconioses in Sweden, pp, 353-357, Scandinavian University Books, Stockholm, Sweden (I960). 8. Ahlman, K.: Asbe&tosu Among Insulating Workers in Finland. Proceedings of the 14th International Congress on Occupational Health, pp. 237-240, Vienna. Austria (Sept. 1966). 9. Dunn, J. E., and J. M. Wem: Cancer Experience of Several Occupational Groups Followed Prospectively. Amtr. }. Pttmc Health 55: 1367 (1965). 10. Krane, W. T., and M. R. Zavon: Occupational Haz ards of Pipe Insulators. AMA Arch. Environ. Health 13: 171 (1966). 11. Cooper, W. C-, and J. R. Tartrshaw; Unpublished Material (1966). 12. Edwards, G. H., and J. R. Lynch: The Method Used by the U. S. Public Health Service (or Enumeration of Asbestos Dust on Membrane Filters. Unpublished (1966). 13. TimbreJ-L, V.: The Inhalation of Fibrous Dusts. Ann. N. Y. Acad. Sci. 132: 255 (1965). 14. Fearns, B.: Personal Communication (1966). J5. Dheessen, W. C., J. M. Daua Valle, T. !. Edwards, .1. M. Miller, and R. R. Sayers: A Study o/ Asbesiosis in the Asbestos Textile Industry. Public Health Bulletin No. 241, U. S. Govt. Printing Office. Washington, D. C. (1938). Received June 20, f967 Errata In the article "The Assessment of the Work Place---A Prerequisite to the Diagnosis of Occupational Chest Disease" by Kenneth M. Morse (A.l.H.A. Journal 28; 135-143, March-April 1967) several errors unfortunately appeared on page 139. In the text table in right-hand column, the time percentage for item "3. Misc. (timbering, bit change, etc.)" should have read 4%. Im mediately following this table the calculation for the time-weighted average concentration (TVVAC) should have been: TWAC = [(38.5 X 4.68) + (6.5 X 1.64) + (4.3 X 0.32) + (3.50 X 0.48' + (4.5 X 0.88)] /8 = 197.9/8 = 24.7 mppcf