PLAINTIFF’S EXHIBIT ;'4 <> . £ - v ' ci o { t i D P M C 01496.1 ( o 't p <* I lam 008012 V-C t LAM 008013 •ejjJ'sS*®' I This report was prepared under Contract NO-1-55176 by the Stanford Research Institute International, Menlo Park, California, for the Division of Cancer Control and Rehabilitation, National Cancer Institute, as an informational and educational resource. Acceptance of the report does not signify that the contents necessarily reflect the official views or policies of the National Cancer Institute, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. DPMC-01498 — LAM 008014 K L..ELL OIL COMPANY library services deer park ■; I •! asbestos: An Information Resource Prevention Branch Division of Cancer Control and Rehabilitation Richard J. Levine, M.D. Editor National Cancer Institute Bethesda, Maryland U.S. Department of Health, Education, and Welfare Public Health Service National Institutes of Health DHEW Publication Number (NIH) 78-1681 ' :j!3 - May 1978 DPMC-01499 LAM 008015 l' ACKNOWLEDGMENTS SRI International (formerly Stanford Research Institute) acknowledges the invaluable advice and assistance of the following individuals during the preparation of this monograph on asbestos: Henry Anderson, M.D. Department of Environmental Medicine Mount Sinai School of Medicine New York, New York Robert E. Baumann, Ph.D. Professor of Engineering Iowa State University Ames, Iowa Arnold Brown, M.D., Chairman Department of Pathology and Anatomy The Mayo Clinic Rochester, Minnesota Jean Spencer Felton, M.D. Long Beach Naval Shipyard Long Beach, California Graham W. Gibbs, Ph.D., Director Occupational Health and Safety Unit Institute for Mineral Industry Research McGill University Montreal, Quebec, Canada Philippe Shubik, M.D., Director Eppley Institute for Research in Cancer Omaha, Nebraska Acknowledged also are the many contributions from the staffs of SRI's Center for Occupational and Environmental Safety and Health, Center for Resource and Environmental Systems Studies, Biorganic Chemical Department, Minerals and Metals Center, and Center for Research on Stress and Health. DPMC-01500 LAM 008016 CONTENTS LIST OF ILLUSTRATIONS LIST OF TABLES . . . FOREWORD................................................................................................................................... xi ACKNOWLEDGMENTS .................................................................................................................... xiii i-. I INTRODUCTION ................................................................................................................ ' 1 l\ II PRODUCTION AND USE OF ASBESTOS FIBERS AND PRODUCTS .................... 9 !* 4i U.S. Consumption of Asbestos Fibers .................................................... U.S. Production and Producers of Asbestos Fibers ......................... End Uses of Asbestos............................................................................................ Handling of Fiber and Products During Their Production ... 9 11 13 15 Mining................................................................................................................ Milling ............................................................................................................... Transportation..................................................... Manufacture of Asbestos-Containing Products ......................... 15 17 18 19 III BIOLOGICAL EFFECTS OF ASBESTOS FIBERS ................................................ 21 Disposition of Fibers in the Body.......................................................... 21 Inhaled Asbestos Ingested Asbestos Injected Asbestos "Asbestos Bodies" ....................................................................................... ....................................................................................... ... ......................................................................... ....................................................................................... Carcinogenic Effects--Human Studies 3> I 21 22 23 23 ..................................................... 23 Evidence of Lung Cancer......................................................................... Evidence of Mesothelioma......................................................... Laryngeal Cancer ..... ............................................................... Digestive System Cancer ......................................................................... Other Cancers...................................... Association of Effects with Fiber Type.................................. Dose-Response Relationship ............................................................... The Cancer Latency Period .................................................................... Incidence of Cancer and Age at First Exposure to Asbestos................................................................................................. Smoking and Asbestos-Related Cancer ............................................ Cancer from Incidental Occupational Exposure .................... Disease in Workers’ Households ..................................................... Cancer in the Neighborhood of AsbestosFacilities ... .24 25 25 26 .26 26 27 29 29 30 31 32 32 iii LAM 008017 ?! ii'-l li Ill IV BIOLOGICAL EFFECTS OF ASBESTOS FIBERS (Continued) Carcinogenic Effects--Animal Studies ...................................................... Noncarcinogenic Effects of Asbestos ...................................................... 32 34 Asbestosis ....................................... ..... ................................... Asbestos Pleural Effusion .................................................................... Pleural Calcification, Diffuse Fibrosis, and Plaques ............................................................... ....... Asbestos Warts ............................................................................................ Animal Studies--Evidence of Noncarcinogenic Effects . . 34 37 37 38 38 OCCUPATIONAL EXPOSURES ....................................................................................... 41 Exposures in Mining and Milling ............................................................... Exposures in the Asbestos Products Industries .............................. 42 42 Friction Products...................................... Asbestos Paper ............................................................................................ Asbestos-Reinforced Plastics ........................................................... Asbestos-Cement Pipe and Sheet .............................. ..... Floor Tile...................................................................................................... Asbestos Textiles ........................................................................................ 4-3 45 45 45 46 46 Exposures in the Utilization of Asbestos-Containing Products 47 Insulation Trades ........................................................................................ Brake and Clutch Repair......................................................................... Installation of Floor Tile, Roofing, and Siding .... Use of Spackling, Patching, and TapingCompounds ... Wearing Asbestos Garments .................................................................... 47 48 48 49 49 V NONOCCUPATIONAL EMISSIONS AND EXPOSURES ................................................ 51 Asbestos Emissions from Natural Sources .................... ..... Asbestos Emissions from Human-Created Sources .............................. Redistribution and Fate of Asbestos in the Environment ... 51 51 52 Redistribution by Air.............................................................................. Redistribution by Water ......................................................................... The Ultimate Fate of Asbestos Fibers....................................... 52 54 54 Exposure to Airborne Asbestos ............................................ ..... 55 Exposure from Ambient Air .................................................................... Exposures from Asbestos Mining, Milling, and Product Manufacture .................................................................... Exposure from Transportation of Materials Containing Asbestos .............................................................................. Exposure from Asbestos Manufactured Products .................... Exposures from Disposal of Asbestos Products and Wastes.................................................................................................. Exposures of Asbestos Workers' Families ................................... 55 Exposure to Asbestos in Drinking Water ................................................. Exposure to Asbestos in Foods and Drugs ............................................ 56 57 58 61 62 62 64 iv DPMC-01502 LAM 008018 VI CONTROL OP THE ASBESTOS HAZARD—PHYSICAL CONTROL ..................... 67 Engineering Measures ........................................................................................ 67 Enclosure...................................................................................................... Exhaust Ventilation .............................................................................. Isolation...................................................................................................... Plant Design............................................................................................ Treatment of Asbestos ......................................................................... Substitution ............................................................................................. 68 68 69 70 72 72 ! Administrative Measures .............................................................................. 75 Limiting the Number of Employees Exposed ......................... Limiting the Duration of Exposure for Any Given Person...................................................................................................... Restrictions on Smoking and Eating ....................................... Smoking Cessation Programs ........................................................... 75 Work Practices, Including Housekeeping and Use of Personal Protective Equipment ................................................................................... 75 76 77 - 77 Housekeeping ............................................................................................ Personal Protective Equipment ...................................................... 78 78 Control in Specific Manufacturing and Consuming Indus­ tries ..................................................................................................................... 80 Asbestos Textile Production ........................................................... Asbestos Paper ........................................................................................ Asbestos-Cement Pipe and Sheet................................................. Automotive Brake and Clutch Repair ....................................... Construction ............................................................................................. Demolition and Rip-out of Asbestos-Containing Insulation................................................ Control of Emissions to the General Environment 80 81 81 81 81 82 .................... 83 Air Pollution Control ......................................................................... Water Pollution Control .................................................................... Waste Water Treatment Processes ................................................. Control of Asbestos Fibers in Potable Water Supplies................................................................................................. Waste Disposal........................................................................................ Identification ........................................................................................ Separation................................................................................................. Secure Transport ................................................................................... Secure Ultimate Disposal ............................................................... 83 83 84 Control During Transportation ............................................................... 85 86 86 87 87 87 87 DPMC-01503 LAM 008019 i VII VIII CONTROL OF THE ASBESTOS HAZARD—MEDICAL MANAGEMENT . 89 . Composition of the Workforce.................................................................... 89 Lung Cancer................................................................................................. Mesothelioma ............................................................................................ Asbestos is................................................................................................. 90 90 92 Early Detection and Treatment of Asbestos-Related Diseases............................................................................................................... 92 Lung Cancer................................................................................................. Laryngeal Cancer ................................................................................... Mesothelioma......................................................'.................................. Cancers of the Alimentary Tract ................................................. Asbestosis................................................................................................. 92 96 96 96 97 CONTROL OF THE ASBESTOS HAZARD—EDUCATION .................................. 99 Goals of Education............................................................................................ Modes of Education—The Written and the Spoken Word . . . The Educators...................................................................................................... 99 100 101 Physicians................................................................................................. Nurses........................................................................................................... Health Educators (Communication Specialists) .... Industrial Hygienists ......................................................................... Union Health and Safety Specialists ....................................... Industrial Safety and Other Training Specialists . . Science/Medical Writers .................................................................... 101 101 102 102 102 ' 102 103 Target Groups for Education .................................................................... 103 Managerial and Supervisory Personnel .................................. Workers in the Asbestos, as Well as Other, Trades . . Retirees and Other Former Workers ............................................ Workers' Families .............................................................................. Occupational Health Professionals ......................... .... 103 104 104 104 104 Assessment of Education's Value .......................................................... 105 APPENDICES A ASBESTOS-RELATED AND -ASSOCIATED MINERALS ........................................ A-l B FEDERAL REGULATIONS OF OCCUPATIONAL EXPOSURE ............................... B-l C MONITORING AND MEASURING ASBESTOS CONTAMINATION .......................... C-l D ANIMAL STUDIES RELATED TO CARCINOGENIC EFFECTS OF FIBERS................................................................................................................ D-l AIR AND DRINKING WATER ASBESTOS CONCENTRATIONS FROM SOME PUBLISHED SOURCES.................................................................... E-l E vi LAM 008020 F SMOKING CESSATION PROGRAMS . . G SOURCES OF EDUCATIONAL MATERIALS H REFERENCES . . . ...................................................... !l! it : :!!' i •k-k i ! C: ii!V f | f' ’T !|| r|! SI i * vii f DPMC-01505 LAM 008021 ILLUSTRATIONS 1 2 3 Distribution of Ultrabasic and Metamorphic Rock Formations in the United States ............................................................... 4 Disposals and Emissions of Asbestos from Asbestos Production, Manufacturing, and Consumption in the United States ........................................................................................................... 53 Locker Room, Shower Arrangement ............................................................... 71 •> f TABLES : .11 Apparent U.S. Consumption of Asbestos Fiber .................................. 10 2 Operating and Nonoperating Asbestos Mines and Mills in the United States....................................................................................... 12 3 Selected Asbestos Products and Their End Uses ............................. 14 4 Major U.S. End Uses of Asbestos Fiber, By Type& Grade . 16 5 Deaths from Respiratory Cancer by Cumulative Dust Exposure.................................................................................................................... 28 Exposure to Airborne Asbestos in Selected Asbestos Product Manufacturing Industries .......................................................... 44 Medical Examinations for Asbestos-Exposed Workers .................... 93 6 . I- ■■ 7 !.jt; ■ii. ij IX DPMC-01506 LAIM 008022 FOREWORD There is increasing realization that asbestos may be present across the entire spectrum of human exposure--in our air, water, food, drugs, cosmetics; in our homes and, most importantly, in our workplaces. There is also developing awareness that several types of cancer may be the con­ sequence of exposure to this material, especially for certain segments of the population. i Recognizing our responsibility to transfer information to the scien­ tific community and the public, the Division of Cancer Control and Rehabil­ itation, National Cancer Institute, is making available this document on asbestos and cancer. Several of the more important objectives of the document are to: (1) present both current and historical evidence of the carcinogenic potential of asbestos; (2) examine potential exposure of the public; (3) describe current intervention and control technology; and (4) discuss the possible prevention roles of various individuals and groups in the community. Dissemination of information is a fundamental prerequisite to the formulation and implementation of action programs for effective cancer control and prevention at the federal, state, and local levels. This document represents work of individuals in many different research fields, and the contributions of all these individuals are acknowledged. The comments of many scientists in the federal government and private sector are greatly appreciated. Particular thanks must be given to Dr. Herman Kraybill and the Interagency Collaborative Group on Environmental Carcinogenesis for their comments and to Drs. Irving Selikoff, Mearl Stanton, Paul Kotin, Elizabeth K. Weisburger, and Kenneth Bridbord for their review and suggestions. Dr. Winfred F. Cancer Institute. Malone served as Project Officer for the National Ima V rh<^/lip Diane J. Fink, M.D. , Director Division of Cancer Control and Rehabilitation National Cancer Institute I xi *• - ••V**'-'- ' 'V DPMC-01507 LAM 008023 ACKNOWLEDGMENTS SRI International (formerly Stanford Research Institute) acknowledges the invaluable advice and assistance of the following individuals during the preparation of this monograph on asbestos: Henry Anderson, M.D. Department of Environmental Medicine Mount Sinai School of Medicine New York, New York Robert E. Baumann, Ph.D. Professor of Engineering Iowa State University Ames, Iowa Arnold Brown, M.D., Chairman Department of Pathology and Anatomy The Mayo Clinic Rochester, Minnesota Jean Spencer Felton, M.D. Long Beach Naval Shipyard Long Beach, California Graham W. Gibbs, Ph.D., Director Occupational Health and Safety Unit Institute for Mineral Industry Research McGill University Montreal, Quebec, Canada Philippe Shubik, M.D., Director Eppley Institute for Research in Cancer Omaha, Nebraska Acknowledged also are the many contributions from the staffs of SRI's Center for Occupational and Environmental Safety and Health, Center for Resource and Environmental Systems Studies, Biorganic Chemical Department, Minerals and Metals Center, and Center for Research on Stress and Health. xiii LAM 008024 Chapter I INTRODUCTION Because of their unique combination of resistance to heat and chem­ ical attack, high tensile strength, and flexibility, fibrous asbestos minerals have long been used by man. The early Greek geographer, Pausanias, speaks of golden lamps made about 430 B.C. with incombust­ ible wicks of "Carpathian flax." The Romans used asbestos as cremation clothes to conserve the ashes of deceased persons of rank. The French emperor, Charlemagne, had a tablecloth of asbestos and is reputed to have impressed his enemies by passing it through fire to clean it. Today, asbestos is found in thousands of commercial products including heat-resistant textiles, reinforced cement, special filters for industrial chemicals, thermal insulation, floor tiles, gaskets, and brake linings. More than 725,000 metric tons (800,000 short tons) of asbestos have been consumed in the United States alone in producing these products in each of several recent years. As a consequence of man's utilization of asbestos, coupled with the natural occurrence of the min­ eral, asbestos fibers are found in the air we breathe, the food we eat, and the water we drink. A Hazard to Human Health ! The fact that asbestos is a hazard to man's health was recognized quite early. In the first century, both Pliny the Elder, the Roman naturalist, and Strabo, the Greek geographer, wrote of a sickness of the lungs in slaves whose occupation was the weaving of asbestos into cloth. However, the association of asbestos with chronic respiratory disease had to be rediscovered in the modern era. A series of case reports was followed by an epidemiologic study published in London in 1930,1 52 years after large-scale mining of asbestos had begun with the opening of a mine at Thetford, Quebec, Canada. The cancer-producing potential of asbestos was not established until 1949, when a report was published describing an excess of cancer of the lung and pleura among individuals dying from asbestosis.^ !j ; | :i j | ;| h |. ! ' ■ j. {[ 1 ; | ?11 It is now clear that among asbestos workers, there is, in addition to the risk of asbestosis, a greatly increased risk of death from lung cancer and from pleural and peritoneal mesothelioma, malignancies that are seldom found in the general population.^Moreover, asbestos has been linked with gastro-intestinal, oropharyngeal, and laryngeal cancer. According to the U.S. Public Health Service, one million persons now living in the United States either work or have worked in the 1 LAM 008025 jj j: : !' J ; i J j asbestos product manufacturing industry. This figure does not include those employed in mining and milling asbestos; those whose work may involve installation, modification, or repair of asbestos products; persons exposed indirectly to asbestos in the course of their work such as at shipyards or in the construction industry; persons living in the neighborhood of an asbestos product factory; or consumer users of asbestos materials. What is "Asbestos?" To the mineralogist, asbestos is the generic name for a group of naturally occurring hydrated mineral silicates of the amphibole or serpentine series that are characterized by fibers or bundles of fine single crystal fibrils. Naturally occurring asbestos fibers typically have length-to-width ratios of the order of 100 and higher. Included in this definition are the following minerals: • Chrysotile • Crocidolite • Amosite, and • The fibrous varieties of anthophyllite, tremolite, and actinolite.* All of these minerals may occur in a nonfibrous form, in which case they are not classified as asbestos. Commercially, chrysotile is the form of asbestos used most. Crocidolite, amosite, and anthophyllite also have some commercial significance. It is important to note that identification of asbestos fibers is relatively simple with macroscopic samples that clearly show the fibrous nature and other unique characteristics of these minerals. Positive identification is based on morphology, crystallographic structure, color, hardness, optical properties, and appearance. However, in the case of microscopic samples, positive identification becomes increasingly difficult, even when special microanalytical techniques are used. The identification of asbestos is complex because many of the min­ erals that are chemically almost identical to different varieties of asbestos (e.g., grunerite to amosite, serpentine to chrysotile) exhibit Crocidolite, amosite, anthophyllite, tremolite, and actinolite are derived from the amphibole series and may be referred to as "amphiboles." 2 DPMC-01510 LAM 008026 perfect prismatic cleavage (the ability to break along well-defined crystallographic planes), so that physical degradation often leads to the formation of minute cleavage fragments that are chemically as well as physically indistinguishable from asbestos fibers. Recent compre­ hensive studies at the U.S. Bureau of Mines have concluded that there is currently no absolute way to distinguish between finely divided asbestos and certain other minerals of similar composition.6 Some minerals other than asbestos that may exhibit fibrous structure are listed in Appen­ dix A. On the other hand, recent biological studies suggest that, in terms of carcinogenic activity, mineral shape and size may be more important -.than chemical nature. ^ ■ The question of asbestos carcino­ genicity can,-therefore, be viewed as part of a broader issue—i.e., tissue modification caused by mineral fibers. Occurrence of Asbestos ; All forms of asbestos develop through several stages of geologic processes (paragenesis) from parent rocks that are transformed into asbestos. Parent rocks of asbestos minerals include basic constituents normally found in ultramafic, dolomitic, or limestone rocks. Transformation may occur under localized conditions of temperature and pressure which lead to recrystallization of other in-situ minerals (metamorphism). It may occur as a result of the action of hot mineral solutions that can dissolve or otherwise alter some minerals to form others (hydrothermal processes). ; i j i;jj |.:j j jj ■, , ; In all of the commercial asbestos deposits, the geologic conditions have been favorable to the development of fibers of sufficient quality and concentration to warrant their extraction. (The same conditions may operate in other mineral deposits but yield asbestos fibers that are too disseminated or scarce to be of commercial interest.) I 1 Minerals and rocks that can contain asbestos are listed in Appen­ dix A. A favorable mineral association is not a sufficient condition for the formation of asbestos—it will form only if special structural and other geologic conditions are met. If asbestos presence is, in fact, established, the minerals and rocks listed in Appendix A would be significant sources of contamination for humans, since they include important raw materials for industry and are mined in commercial quan­ tities, worldwide. j l ; The areas of the United Stated having basic geologic constituents associated with the formation of asbestos are shown in Figure 1. Again, this graphic does not necessarily depict actual asbestos occurrence but. 3 DPMC-01511 LAM 008027 i. i 'f* > j LAM 008028 rather, is an overview of the areas that are more likely than others to provide the geologic setting associated with formation of asbestos. Although deposits of asbestos may be found throughout the United States, asbestos is commercially mined and milled at only five loca­ tions, in the states of California, Arizona, and Vermont. (Most of the asbestos consumed in the United States is imported, nearly all of it from Canada.) In addition to commercial mining and milling of asbestos, human-created occurrences of asbestos fiber may result from the mining and milling of mineral ores associated with asbestos; from the inadver­ tent disturbance of asbestos deposits by activities such as farming and road building; from the transportation of asbestos ore, milled fiber, products, and wastes; from the manufacture, use, repair, and demolition of asbestos-containing products; and from the disposal of asbestos wastes. All are discussed in succeeding chapters of this monograph. Regulation of Asbestos-Fiber Emissions A recommendation for limiting exposure to asbestos in U.S. industry was made in 1938 by the U.S. Public Health Service.® The recommended limit, an airborne concentration of less than 5 million particles per cubic foot, was formally recognized in 1964—as a guideline issued by the Bureau of Labor Standards. No legal regulations were established until passage of the Occupational Safety and Health Act of 1970 and establishment of the Occupational Safety and Health Administration (OSHA). I; !,l ! Occupational Exposure OSHA regulations apply directly to all private employers, including federal’government contractors, but not to federal, state, or local government agencies. Federal agencies are required to establish their own occupational safety and health programs consistent with the stand­ ards of the Act and subsequent OSHA regulations. States are encouraged by the Act to develop programs and regulations, for private employers, that are at least as effective as OSHA regulations and can, under these conditions, assume responsibility for enforcing standards—at the timeof this writing, 24 states have programs of their own.9 The current OSHA limit on occupational exposure to asbestos fibers is an 8-hour time-weighted average of 2 fibers per milliliter, no longer than 5 micrometers, with a length-to-width ratio of at least 3:1, detected by a method using phase-contrast (optical) microscopy. ,1 ii i The permissible levels of occupational exposure to asbestos con­ tained in all federal regulations (and one proposal) are summarized in tabular form in Appendix B. Also, the provisions of these regula­ tions for method of compliance, monitoring, medical surveillance, edu­ cation, and the keeping of records are summarized there. i. (' 5 DPMC-01513 LAM 008029 J Emissions to Air and Water, Disposal of Solid Waste, Transportation A national air emission standard for asbestos, first published in 1973,^0 requires either the institution of specified air-cleaning meth­ ods or else no visible emissions (except water) to be released to the outside air. The standard applies to the milling of asbestos (but not to adjacent storage depots); manufacturing or processing of specified products; renovating or demolishing certain buildings (but not ships) containing more than a specified amount of friable asbestos insulation; and to wastes containing commercial asbestos or products of asbestos mining and milling. Friable or spray-on insulating materials, except when applied to equipment or machinery, must contain no commercial asbestos; however, spray-on paints, decorative materials, and weather­ proofing are not regulated. Under the terms of guidelines and standards promulgated in 1974 and 1975, certain asbestos-manufacturing operations were to achieve, by July 1, 1977, wastewater effluent limitations requiring application of the best practicable control technology currently available; and by July 1, 1983, except for operations involving solvent recovery, there is to be no discharge of wastewater pollutants to navigable waters.H Federal agencies are directed by two Executive Orders to monitor, evaluate, and control their activities so as to protect and enhance the quality of the environment and to conform to air and water quality standards of the Clean Air Act and the Federal Water Pollution Control Act. Food, Drugs, Consumer Products The Food and Drug Administration (FDA) has reviewed several com­ mercial practices that may result in asbestos contamination of food and drugs and, in January of 1976, revoked approval for use in foods of sodium chloride (salt) produced by the electrolytic diaphragm process. In the absence of more-reliable data on background concentrations of asbestos in water and the contribution of asbestos filters to levels of asbestos found in ingestible products, the FDA has not regulated the use of asbestos filters for filtering edible foods, beverages, and nonparenteral drugs.13 The agency has, however, enacted regulations to limit asbestos and other fibrous materials in parenteral drugs.^ The FDA has approved (1) the use of asbestos as a component of various types of food-contact articles in which contamination of food is not 6 DPMC-01514 LAM 008030 likely to occur, and (2) the use of talc, in which asbestos is a possible impurity, in cosmetics.* The Consumer Product Safety Commission has banned general-use garments containing asbestos. The use of asbestos in special garments such as fire-fighting suits is permitted, but only if they are con­ structed so that asbestos fibers will not become airborne under normal conditions of use.l^t i Constraints on Monitoring and Measuring Asbestos Levels As will be brought out later in this monograph, it is simply not known what attributes of asbestos it is that constitute a health hazard—size, shape, mass, type etc.—nor is it known what amount is hazardous or over what period of time. The U.S. federal occupational standards are, perforce, an attempt to optimize what is known about the health hazard with the technical and economic practicalities of measuring the substance. For example, by using phase-contrast optical microscopy, rather than the higher resolution electron microscopy, it is not possible to count all the fibers and not always possible to even distinguish between asbestos and other fibers (as noted previously); electron microscopy, on the other hand, is time-consuming and expen­ sive. The difficulties of measuring and identifying are of such pro­ portions that there are extreme variations in the measurement of a sample, both within a laboratory and among laboratories. i I t As a consequence, the reader should always bear in mind the pos­ sible grossness of measurements referred to throughout this document, even when they are expressed in terms that bespeak of precision—e.g., the decimal point. At the same time, the fact remains that asbestos is a human carcinogen and that, as such, is a suitable subject for treat­ ment in this document, the prime purpose of which is helping man control cancer. The constraint on monitoring and measuring asbestos is such, nevertheless, that it is the subject of more extensive treatment in Appendix C of this document. Talc is listed as a "generally recognized as safe" (GRAS) substance for use in paper, paperboard, and cotton food packaging materials; as an anticaking agent for forms used in molding various food shapes and in chewing gum base; and to coat polished nonenriched rice, as a free­ flow agent, and as a vehicle for enrichment formulas.15 An FDA ruling on talc as a direct food or drug additive has been deferred until an acceptable analytic method can be developed.1^ ^Full attainment of the desired result of regulation inevitably requires adequate means of enforcement. Legal powers of enforcement as well as de facto enforcement practices differ widely among the various govern­ ment agencies having statutory authority. See Reference 17 for an ex­ ample of divergence of enforcement practice in just one regulatory agency from what is required by law. J DPMC-01515 LAM 008031 ***** Summarized in the next four chapters are: production and uses of asbestos fiber and fiber-containing products; the biological effects, carcinogenic and noncarcinogenic, of exposure to asbestos; occupational and nonoccupational exposures and exposure levels. In the final three chapters, strategies and programs for the control of the health hazard represented by human exposure to asbestos are set forth. 8 LAM 008032 Chapter II PRODUCTION AND USE OF ASBESTOS FIBERS AND PRODUCTS Although some exposure of humans to asbestos fibers in air and water is always possible as a result of the weathering of asbestoscontaining rock, it is man's large-scale commercialization of the mineral that has engendered greater health risk. In this chapter, the major facets of such commercialization in the United States are reviewed— consumption and production volumes; categories of manufactured goods; and processes for mining, milling, transporting, and manufacturing asbestos and asbestos-containing products.* U.S. Consumption of Asbestos Fibers During the five years ending in 1975 the amount of asbestos fiber apparently consumed^ in the United States averaged some 800,000 tons annually, although between 1974 and 1975 apparent consumption declined 27% from 856,000 to 629,000 tons.t It is expected that consumption will have recovered to about 820,000 tons in 1976. The sharp decline between 1974 and 1975 reflects not only a market affected by a sharp recession, but also a substantial interruption of supply associated with work stoppages, a landslide at a major mine, and a serious fire at an asbestos mill in Quebec, Canada. The estimated U.S. apparent consumption of asbestos fiber for the 1971-75 period is shown in Table 1. It can be seen in Table 1 that most of the asbestos fiber used in the United States is imported (about 90%). Nearly all of this imported asbestos is chrysotile fiber that comes from Canada (96.5% in 1974). The This chapter includes information obtained through a special survey of industry carried out in the Fall of 1976 by the Mineral and Metals Center, SRI International. t "Apparent" consumption—i.e., production plus imports, plus net ship­ ments from government stockpiles if any, less exports. Apparent consumption figures do not take into account any changes in inventory levels of manufacturers and therefore differ from "actual" consumption figures (an example of which is found in Table 4 in this chapter). ^Volumes in this chapter are expressed in short tons (2,000 pounds) in accordance with industry practice. 9 LAM 008033 : !| :' ’j ; ^ ,<( j I Table 1 APPARENT U.S. CONSUMPTION OF ASBESTOS FIBER (Thousands of Short Tons) 1971 1972 1973 1974 1975 Production 131 132 150 113 100 Imports 681 736 792 776 575 Stockpile releases 10 13 7 29 4 Exports 54 59 66 62 50 768 822 883 856 629 Apparent consumption Source: U.S. Bureau of Mines, Commodity Data Summaries, 1976. Republic of South Africa accounted for some 3% of the U.S. imports in 1974 (crocidolite and amosite fibers), and a number of countries sup­ plied the remainder. A substantial portion of Canadian output is pro­ duced there by U.S. companies that manufacture asbestos products. It should be noted that in addition to importing both crude and milled fibers, the United States imports products manufactured from asbestos. In 1974, for example, the value of products exported from Canada to the United States was as shown below:^ Canadian Dollars (millions) Brake linings and clutch facings $0.9 Building materials 3.7 Other products 3.2 Total $7.8 However, the value of imported products is not large compared with U.S. domestic shipments, which, for example, totalled $742.6 million in 1972.2 The U.S. Bureau of Mines has estimated that U.S. demand for asbes­ tos in the year 2000 will range between 1.0 million and 1.8 million tons.^ It is also possible, however, that substitution of other 10 DPMC-01518 008034 materials for asbestos could result in a lower level of demand. substitution could occur for a number of reasons such as: • More rapid price increases for asbestos than for its competitive products. • Health and safety considerations. • Lack of availability (an industry expert has estimated that by 1980 supply could fall short of potential world demand by about 500,000 tons, or about 10% of world demand). This ! I U.S. Production and Producers of Asbestos Fibers The volume and value at the mines of asbestos fiber production in the United States during recent years is shown in the tabulation that follows: I Production (Thousands of Short Tons) Value Per Ton Total Value (Millions of Dollars) 1971 131 $ 93 $12.2 1972 132 102 13.5 1973 150 121 18.2 1974 113 158 17.9 1975 100 182 18.2 r The decline in production volume from the all-time peak of 150,000 tons in 1973 resulted primarily from the closing or reduction in output of several mines such as GAF Corporation's Lowell Vermont mine (acquired by the Vermont Asbestos Group), Pacific Asbestos Corporation's mine near Copperopolis, California (later reopened by Calaveras Asbestos Limited), and the Christie mine of'Coalinga Asbestos Company, Inc., at Coalinga, California (a 15,000-ton-per-year mine that has remained closed). The average domestic production of only 125,000 tons annually during the 1971-75 period is a relatively small fraction of the nearly 800,000 tons consumed annually in the United States during those years. As a result of an increase in the production volume and average value per ton in 1976, the value of U.S. asbestos fiber production could be in the range of $25-30 million in 1976 (11-13% of the mine/mill value of all asbestos likely to be consumed during the year). U.S. asbestos mines and mills, their locations, output, and employ­ ment are shown in Table 2. The current total mill capacity is on the 11 DPMC-01519 LAM 008035 LAM 008036 SRI— In d u s try c o n ta c ts and tra d e jo u rn a ls . OPERATING AND NONOPERATING ASBESTOS MINES AND MILLS IN THE UNITED STATES order of 143,000 tons per year (all in the form of chrysotile fibers). California mines and mills account for about 70% of total U.S. output. It is difficult to predict changes in U.S. asbestos output because such changes will be a function of costs, including environmental costs, in the United States as compared with costs in Canada and other sources of supply. Neither current nor projected costs are published. End Uses of Asbestos The high tensile strength, flexibility, heat and chemical resis­ tance, and favorable frictional properties of asbestos fiber make it adaptable to a large number of uses. Depending on the length of fibers and other characteristics, asbestos can be: Carded, spun, or woven Used as structural reinforcement of materials such as cement, plastic and asphalt Laid and pressed to form paper. Some authorities, such as the U.S. Bureau of Mines, state that there are more than 2,000 discrete uses of asbestos; others, such as the Asbestos Information Association and Canada's Department of Energy, Mines and Resources, suggest that there are upwards of 3,000 uses. A selected few of the many applications are shown in Table 3. The properties of asbestos fibers determine the uses to which the fibers are put. Properties of major importance are length distribution, bundle diameter distribution, harshness, tensile strength, and surface activity. Other considerations include color and content of iron and dust. The relative-strength standard developed for chrysotile asbestos by the mining industry in Quebec is a convenient basis for delineating some major uses. For example: * • Long fibers (Groups 1 and 2 and 3) are used in textiles, electrical insulation filtration media, and maximumstrength asbestos cement products. • Medium length fibers (Groups 4, 5, 6) are used as rein­ forcing fillers in asbestos cement products, in friction materials such as brake linings and clutch facings, in paper, and in pipe covering. No. 1 crude is 3/4 inch staple and longer (to nearly 6 inches). No. 2 crude is 3/8 to 3/4 inch staple. Other groups are milled fibers. 13 DPMC-01521 LAM 008037 3 OO 3 3 •H 4J 4J 3 3 3 O •H CJ 3 3 » CO 3 4-> T5 3 3 ♦H 3 3 04 tn 00 >, 3 rH O an a lh CL CL O tH ■H 3 3 «H 3 CL 3 00 4J D O 3 *H 4J 3 •H 3 U *H 3 a 3 B 3 3 CL *3 3 Li 3 3 4-1 •H 3 tH •H X. 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C 0) H T3 4J *H O C V4 c o e cl o 3 *h li a. 3 cn g auN 3 ‘Em U O E <0 at ♦H tH 4J o 00 O0 O *H 3 4J 3 tH Uh X iH 3 •H 3 -x-^ O Hi Hi LH g 4-1 4-1 0 3 O g 3 3 3 3 O 0 3 tH CJ CL O CJ •H Li 4J CJ 3 tH W L> Li 3 3 4-1 CL 3 3 3 Li X •o H A s b e s to s In fo r m a tio n A s s o c ia tio n /N o r th A m e ric a . SELECTED ASBESTOS PRODUCTS AND THEIR END USES *3 at (0 u o h •H o 4-1 LH 0) 3 3 •H rH at Cl, a- 1 a o S o u rc e : at a 0) •H O CL 4J 3 4-1 at 3 X at 3 E < at CJ 14 DPMC-01522 LAM 008038 • Short fibers (Groups 7, 8) are used as reinforcing filters in plastics, floor tile, and asphalt and in paints and oil-well drilling muds. The consumption pattern for asbestos fiber in the United States is shown in Table 4. The construction industry—including new building, renova­ tion, and maintenance—accounts for an estimated 70%-80% of total U.S. consumption. The first four uses shown in Table 4, which are constructionindustry related, account for only 65% of the total use, but a portion of some of the other uses is associated in various ways with the con­ struction industry. Several other aspects of Table 4 are noteworthy: • Chrysotile fiber accounts for a very high proportion of total asbestos use (94% in 1974). • About 98% of the crocidolite is used in the production of asbestos cement pipe, because of (1) its hardness, brittleness, and high tensile strength, which add to the rigidity of the end product, and (2) its superior fil­ tration qualities, which enhance the drainage of water, permitting the cement to dry more rapidly. • Asbestos cement pipe and sheets account for a large pro­ portion of total use (38% in 1974). • A very large proportion of total asbestos use is accounted for by the shorter-length fibers (Quebec Grade 7 chrysotile alone accounted for nearly 40% of the total use in 1974). The transportation industry uses about 14% of all the asbestos con­ sumed. The applicance industry uses some 5%-6% of the total.5 Handling of Fiber and Products During Their Production Producing the many asbestos-containing products that are used involves mining asbestos ore; milling, or hand-separating, the fibers from the ore and from each other; transporting both ore and fiber; and manufacturing the products themselves. These four general processes are reviewed briefly in the sections that follow. Mining Most asbestos ore is mined in surface operations. Of the five U.S. mines in operation, four are surface mines and one is underground.* Each operating mine is associated with a mill that processes the ore. For a description of each mine and a discussion of the mining, milling, and dust-control procedures, see National Environmental Research Center, Characterization and Control of Asbestos Emissions from Open Sources, North Carolina, September, 1974. 15 DPMC-01523 LAM 008039 LAM 008040 S o u rc e : U .S . Bureau o f M in e s : FIBER, BY TYPE AND GRADE (S h o rt Tons) 1974 END USES OF ASBESTOS M in e ra l Y earbook ( p r e p r in t) , 1974. MAJOR U .S . In three cases, the mine and mills are at the same location, but two mines send their ore by truck to mills 32 and 55 miles away. (See Table 2.) The methods used to mine asbestos ore in the United States are described below. Area strip mining, as practiced in the California operations, entails removal of the ore by earth-moving equipment from shallow deposits—in one instance without even the need for blasting. Generally, a shallow overburden with low concentrations of asbestos fiber must be removed. Open pit mining, as practiced in the Vermont operation, is similar to area strip mining operations except that to follow the fiber veins, the workings are much deeper. Blasting and removal of ore occur primarily on the sides of the pit along terraces that spiral down around the sides of the pit toward the bottom. Underground mining, as practiced in the Arizona operation, entails following the veins of ore with shafts, galleries, and drifts, using blasting and earth-moving equipment. This operation is followed" by transporting ore to the surface, where it is processed further. At the typical asbestos mine, coarse ore is crushed by a jaw or gyratory crusher to a size that can be accommodated by the mill. Oversize rock is separated by rotating cylindrical trommel screens and is crushed in a secondary crusher, usually of a conical type. The ore streams are conveyed to driers—rotary kilns in larger installations— where moisture in the ore (up to 30% by weight) is removed. The dried ore is then stored, with large amounts being held to allow for varia­ tions in fiber demand and mine production over time. Prior to milling, dried ore is conveyed to an additional crushing step. Milling Milling, done primarily by hammer mills (fiberizers) or crushers, serves to free the fibers from the rock and separate the fibers from each other. In general, longer-length fibers in the final mix bring higher prices. Hence, it is desirable to hold the mechanical working or fibers to a minimum since, although the fibers have very high ten­ sile strength, they are so fine that they are easily broken. The most expensive grades of fiber are not mechanically milled at all; rather, they are hand-separated ("cobbed") from the surrounding rock into bundles of relatively long fibers with lengths of 3/4" or more. Such fiber is valued for manufacturing asbestos textiles. The solution to the problem of maximizing the recovery of fibers other than hand-cobbed, in all but one of the asbestos mills in the United States, is to use mechanical means to free the fiber bundles from the rock, but to use air aspiration systems to separate and convey the 17 J DPMC-01525 LAM 008041 fibers. In these systems, the ore is shaken on progressively finer screens through which small rocks and fiber bundles pass for further treatment while larger rocks are retained for further crushing or for conveyance to tailing dumps. The fibers freed are removed by the flow of air through powerful suction hoods. Separated fibers are caught in dry cyclones and conveyed to screens that separate them according to size. After sizing, the fibers are sent to bins for storage. Subse­ quent operations include removing the fibers from the storage bins, blending in fibers of different sizes to produce the desired final shipping specification, and bagging for shipment. The one exception to the air-aspiration milling system is found in a California mill that processes the loose fiber ore by a wetseparation system. Transportation Conveyors and trucks are used at mine and mill sites to move ore from mines to mills. Asbestos fibers typically are shipped from the mills in 100-pound, multiwall, paper or plastic bags.* (One producer reports the use of a stronger, woven, polyvinyl bag for some shipments.) Bags are pressurepacked to reduce bulk, damage, and dust. It is customary to tape rip­ ped or punctured bags when the damage is discovered; yet the fact that the fibers are tightly packed may often prevent them from escaping even if the damaged area is not repaired. The technology is now available to pack asbestos even more tightly—i.e., to form blocks with twice the density of fiber shipped in conventional bags, a 100-pound block having a volume of about one cubic foot. Palletizing is used almost universally, with the bags glue-locked to each other or shrink-wrapped to the pallet (wrapped with a film of plastic which is then shrunk) to stabilize the load. Much of the asbes­ tos shipped is further unitized by being loaded into sealed railroad boxcars or shipping containers. Sometimes the asbestos is made into pellets, which, rather than being packed in bags, are loaded on and off railroad boxcars by gravity flow through pipes. The majority of Canadian chrysotile fiber is shipped into the United States in conventional sealed railroad boxcars in which the con­ tents are protected by inflated-rubber bags. The modern damage-free bulkhead cars are being used as they become available. The cars are routed directly from the Canadian mills to the U.S. manufacturing plants. Smaller proportions of chrysotile imports from Canada are received in containers, either by rail or by ship via the Atlantic * Some manufacturers can add the bags, along with the fibers, to their product mix without even opening them. 18 LAM 008042 I Ocean. All fiber from South Africa, the source of all U.S. imports of crocidolite, arrives by ship in containerized bags at Gulf Coast ports. U.S. exports of fiber, virtually all of which are from California and destined for Mexico, Central America, and the Far East, leave the mills by both rail and truck. Containerized ocean shipments leave from ports such as Stockton, Sacramento, Oakland, and San Francisco. Although 100-pound bags are by far the most widely used in the industry, one of the California mills, for the convenience of its customers, ships all of its fibers in bags weighing from 10 to 50 pounds. One company plans to shrink-wrap each paper bag individually, for added protection, since some users buy in less-than-pallet lots. A representative of one of the world’s largest shippers of asbestos reports that about 2% of the bags shipped sustain some damage. Manufacture of Asbestos-Containing Products Production processes used in the consumption of asbestos are high­ lighted below for selected products. Asbestos cement products use the largest amount of asbestos of any product category (about 317,000 tons, or 38% in 1974). Specific products include wallboard, pipe, shingles, and blocks. Advantages of the products over their nonasbestos counterparts are better tensile strength, strength-to-weight ratio, strength under heat stress, resis­ tance to acid, and smoothness of finished surface (critical to ensure laminar flow in pipe used for transport of liquids). Asbestos fiber (primarily chrysotile, but also others to a limited extent) is mixed, either wet or dry, with portland cement and silica in proportions ranging from 10% to 70% of the total material. If the mixing is done dry, the mixture is generally metered in a flat layer onto an open surface, where the requisite water is applied by over­ head spray. The resulting layer, much thinner than the final product, is then wound onto mandrels in a spiral mat (for pipe) until the requi­ site thickness is built up, or is layered flat (for wallboard or shingle forms). The same winding or layering process may be used for wet-mixed products, or the mixture may be cast. Finishing processes for the dried cement products vary with performance requirements and type, and may include grinding, drilling, sawing, or cutting. Asbestos can be made into the full range of textile products— from nonwoven lap and felt, through yarn and cord, to woven cloth, rope, and tube. The asbestos fibers required for textiles are significantly different from those used for other asbestos products; they must be quite For a more detailed discussion of the manufacture of asbestos-containing products, see U.S. Environmental Protection Agency, "Development Docu­ ment for Effluent Limitations, Guidelines and Standards of Performance: Asbestos Manufacturing," Washington, D.C., 1973. 19 DPMC-01527 LAM 008043 long to be spinnable. Spinnable fiber is sometimes obtained by textile producers in hand-cobbed, "crude," form—i.e., as unopened, rock-free fiber blocks or bundles—since, as noted previously, it is difficult to protect fiber length during milling operations. | I If the fibers are received as crude, they are opened in edge (knife) mills into small bundles and then milled into extremely fine flexible fibers. The resultant fibers, as well as being more delicate and breakable, are also more "floatable,11 leading to a greater emission potential per unit weight. Once the fibers have been adequately opened and fluffed, they may be blended with up to 20% of a cellulosic fiber such as cotton, the specific material chosen depending upon the appli­ cation of the final product. The subsequent processes, such as carding, lapping, roving, spinning, and weaving or braiding (as required) are all performed on equipment essentially identical to standard textile machinery. Asbestos is used in vinyl and asphalt floor tiles as a filler and reinforcement to provide strength and stability without reducing flexibility and compressibility. Very short fibers are used, compris­ ing 8-30% of the total weight. In the case of vinyl tile, for example, polyvinyl chloride resin serves as the binder, limestone and other materials are used as fillers, and pigments and chemical stabilizers make up the rest of the typical mix. The manufacturing process is typically a 24-hour operation that includes weighing, mixing, heating to about 150°C, decorating, calendering, cooling, waxing, stamping, inspec­ ting and packaging. Friction products and gaskets typically contain 30-80% asbes­ tos, generally in some sort of organic binder. In friction products, the asbestos is used for its unique combination of strength, compaction characteristics, friction properties, and stability at high temperatures. Asbestos is used in these products in two different ways: (1) the asbestos, as loose fiber, is mixed with the binder; or (2) the asbestos, as either matted or woven textile, is impregnated with the binder. The low total volume of the latter process is because it is used only in special situations, generally in gaskets, where dimensional stability and elasticity are of significance. | Asbestos paper has essentially the same properties as ^he usual cellulose-based paper, except that it has superior thermal insula­ tion properties and fire resistance. It is used primarily as building paper (roofing and flooring) although it has been reported that the above-mentioned qualities also find use in high-quality-bond document papers. Asbestos paper is made using the same processes as those used for standard woodpulp papers, but the raw materials mix, by weight, might be 70-90% asbestos fibers (typically short in length), china clay and starch (or sodium silicate) as the binders, plus other constituents that provide special properties. I i 20 vj DPMC-01528 LAM 008044 | Chapter III BIOLOGICAL EFFECTS OF ASBESTOS FIBERS As noted in the Introduction to this monograph, asbestos fibers are known to cause cancer. In this chapter, (1) a summary of what is known about the disposition of these fibers in the body is followed by (2) a description of the carcinogenic effects of the fibers, based on human studies as well as animal experimentation; also included is (3) a dis­ cussion of the noncarcinogenic effects of asbestos fibers. Disposition of Fibers in the Body Technical difficulties associated with the assay of biological tissues for asbestos have limited the amount of information available about the disposition of asbestos. Almost all data have come from animal experiments in which asbestos was monitored by electron micro­ scopy or radiotracers. Asbestos fibers typically enter the body by inhalation or ingestion. - Inhaled Asbestos The disposition of asbestos fibers entering the respiratory tract is not fully understood. Certainly some fibers are ultimately deposited in the airways and lung tissue. Some could also be expectorated or con­ veyed to the gastrointestinal tract by airway clearance mechanisms and possibly some to the pleural and peritoneal cavities via lymphatic drainage. Of asbestos fibers found at autopsy in human lungs, a majority are less than 5 pm in length;seldom do they exceed lengths of 200 pm or diameters of 3.3 pm.3 One autopsy study of persons with occupational exposure demonstrated that all asbestos fibers examined in the lung were less than 0.5 pm in diameter.^ This preponderance of small fibers in part reflects their ability to remain suspended in air for longer per­ iods than larger fibers, but it is also a function of their deposition and clearance characteristics once they enter the respiratory tract. It is also possible that some fibers may be fragmented as the result of biological activity within pulmonary tissues. Longer fibers are screened more effectively by the nasal hairs. Inside the upper respiratory tract, fibers are deposited through the forces of gravitational sedimentation and impaction at points where the air stream changes direction; and these depositions depend largely on 21 DPMC-01529 LAM 008045 fiber diameters.3,4 jn the small airways, especially at airway branch points, the collision cross-sectional area, which is a function of fiber length, is of greater importance.3 As a result of these obstacles, a greater proportion of fibers reaching the gas-exchange surface of the alveoli may be small, compared with fibers entering the upper respira­ tory tract. Studies with mammalian cells in culture indicate that these shorter fibers (usually less than 5 pm) may be engulfed by alveolar macrophages and transported to lymphatic channels or the mucociliary blanket for excretion. Longer fibers may be only partially engulfed or may be engulfed by several macrophages at once.*7 Data from autopsies of humans have suggested that some fibers may enter alveolar lymphatic channels and be carried to hilar and mediastinal lymph nodes.® Numerous fibers can be found in the pleura, a serous membrane which covers the surface of the lungs, thoracic diaphragm, and . chest wall; how they gain access to the pleura is not known. Generally, the concentration of fibers in the pleura is less than in the lung it­ self, but in some areas of the pleura, fiber concentrations similar to those within the lung tissue have been observed.9 Ingested Asbestos Most asbestos fibers entering the gastrointestinal tract are prob­ ably excreted with the feces. Although it has been reported in one study that there is little evidence of asbestos fibers^ penetrating the walls of the gastrointestinal tract, there have been animal studies showing such penetration. In a study reported in 1965, chrysotile fibers were found in the lining of the colon in rats fed a diet contain­ ing a massive amount (6%) of chrysotile asbestos.^ In another study, fibers of amosite asbestos suspended in saline, when placed into an isolated segment of rat jejunum in vivo, were found penetrating and within the jejunal wall.f^ One recent study of rats fed 250-300 mg of asbestos per week for a year did indicate that if penetration of the gastrointestinal tract lining does indeed occur, the number of In an experiment with rats, about one-third of inhaled asbestos (crocidolite) was deposited on the surface of the respiratory tract. Half the amount deposited at inhalation was found immediately afterward in the gastrointestinal tract, nose, pharynx, and larynx; clearance from these latter respiratory tissues to the gastrointestinal tract was practically complete within an hour. Of the remaining crocidolite deposited in the lungs, one-quarter had been evacuated at the end of the month.5 In another-study of rats exposed to amphibole asbestos for six months, 41%-74% of the asbestos found in the lungs immediately after exposure had been removed within 18 months.® 22 DPMC-01530 LAM 008046 I penetrating fibers would be very small (90% probability of less than 1500 fibers). Injected Asbestos Asbestos injected into the bloodstream is rapidly removed and deposited in various tissues, with highest concentrations observed in lungs, liver, and spleen.14,15 Limited evidence suggests that asbestos in the blood may be transported across the placenta of rats.16 In mice, asbestos injected subcutaneously migrates along lymphatic pathways from the injection sites. Fibers accumulate in lymphoid tis­ sues, particularly in regional lymph nodes, and are usually contained within macrophages. Small numbers of fibers may be found in the spleen, pleura, liver, kidneys, and brain.1? "Asbestos Bodies" Approximately 10% to 30% of the fibers retained by human lungs (usually longer than 5 pm) become coated with mucopolysaccharide and hemosiderin to form yellow-to-brown rod-shaped structures with clubbed ends, often beaded along their length.1® These structures were first called "asbestos bodies," but now they are frequently referred to by the more general term, "ferruginous bodies," since identical structures may result from the coating of fibers other than asbestos. It has been hypothesized that this coating, laid down by engulfing macrophages, renders the fibers biologically less active. It is thought that a certain balance is achieved between the forma­ tion of asbestos bodies and their dissolution or excretion.19,20 Asbestos bodies found in the sputum are strong presumptive evidence of asbestos exposure. Occupational exposure as brief as one day and as long ago as ten years has been shown to produce sputa containing asbes­ tos bodies.20 Asbestos bodies in lung smears or tissue (unlike those in sputum) are commonly found among residents of urban areas who may never have been exposed to asbestos in the workplace.21-23 Asbestos bodies or fibers have been detected in extra-pulmonary tissues of persons occupationally exposed to asbestos: in tonsils, thoracic and abdominal lymph nodes, pleura, peritoneum, liver, spleen, pancreas, kidney, adrenals, and small intestine. The numbers found appear to be far fewer than in the lung.8>24 Carcinogenic Effects—Human Studies The many observations, both case reports and epidemiologic studies, of cancerous effects among humans exposed to asbestos fibers could be 23 DPMC-01531 LAM 008047 looked at from a number of points of view, but the ones used here are: types of cancer; fiber type; dose-response relationship; latency; age at first exposure; smoking; indirect occupational exposure; household expo­ sure; and residential exposure. The section on human carcinogenic effects is followed by a summary discussion of animal experiments and asbestosrelated cancer. High rates of lung cancer have been observed in asbestos workers exposed to all commercial asbestos types. Among some groups of asbestos workers, approximately 20% of all deaths are caused by lung cancer where the proportion of deaths expected from this cause would be only about 5%.25 Pleural and peritoneal mesotheliomas* are a frequent occurrence among occupational groups exposed to chrysotile, crocidolite, and amosite. Estimates for certain occupational groups suggest that as many as 8%-ll% of deaths may be due to mesothelioma, a relatively rare cause of death in the general population.26 Some occupational groups exposed to asbestos have, furthermore, demonstrated an excess of other cancers, especially of the larynx and gastrointestinal tract. Asbestos exposure leading to an excess of cancer may occur among groups exposed indirectly, as in shipyard workers or in groups mining other minerals that may contain asbestos as a contaminant. Mesothelioma also has occurred among persons living in the homes of asbestos workers or in the vicinity of asbestos facilities. Both cigarette smoking and occupational asbestos exposure individ­ ually increase the risk of lung cancer but, together, they act to pro­ duce a risk of lung cancer that exceeds the sum of their separate risks. Evidence of Lung Cancer The evidence that asbestos is a cause of lung cancer is over­ whelming. Lung cancer was first linked with exposure to asbestos in 1935, when three cases of asbestos is and carcinoma of the lungs were found at autopsy in asbestos textile workers.27>28 Other case reports followed. In 1949 the Chief Inspector of Factories of England and Wales examined 225 deaths from asbestosis or in which asbestosis had been proved at autopsy. Cancer of the lung or pleura was found in 31, or 13.2%. This was not characteristic of other pneumoconioses; among 6,884 deaths with silicosis at autopsy, for example, only 91, or 1.32% had cancer of the lung or pleura.29 Further evidence implicating asbestos in the etiology of lung can­ cer came from a matched-pair case-control study published in 1954. Upon classifying by 5 years or more employment in occupations Mesothelioma is a term used to refer to a tumor made up of cells from the pleura or peritoneum. 24 LAM 008048 involving asbestos exposure (steam fitters, boilermakers and asbestos workers), 10 patients with lung cancer but only one control had been so employed.30 In a study reported one year later, 11 of 113 workers employed in an asbestos textile factory in the United Kingdom for at least 20 years were found to have died from lung cancer. By applying to this group age-specific mortality rates for lung cancer in the general population, 0.8 deaths would have been expected. The ratio of observed to expected deaths, therefore, was greater than 13.31 Continued study of workers at this factory has shown a reduced risk of lung cancer, although still two- to three-fold in excess, among workers first employed after 1933, when regulations for control of asbestos exposure in the United Kingdom had gone into effect.32,33 Numerous other studies have independently confirmed an increased risk of lung cancer in various occupational groups exposed to asbestos.25,34-39 Evidence of Mesothelioma There is also overwhelming evidence that asbestos is a cause of pleural and peritoneal mesothelioma. Cases have been described in per­ sons with occupational and nonoccupational exposures. The first case report of a pleural neoplasm related to asbestos exposure appeared in 1933.40 Additional cases were noted in the 1940s,41-43 ancj ^954 a peritoneal tumor was reported.44 However, it was not until 1960, with the publication of a series of cases from South Africa, that the asso­ ciation between mesothelioma and asbestos exposure was generally recog­ nized. Of 33 South African patients with mesothelioma, 32 gave a history of occupational exposure to asbestos or residence in a crocidolite min­ ing area.^5 Subsequently, a plethora of individual case reports, case series, case-control studies, and studies of the mortality of occupa­ tional groups have related the occurrence of mesothelioma to a history of exposure to asbestos.25»39,46-53 The ratio of pleural to peritoneal tumors varies considerably in different studies, but peritoneal tumors seem to be associated with heavier exposures and with asbestosis.54-56 Laryngeal Cancer The evidence casually linking asbestos and laryngeal cancer is highly suggestive. In a study of 119 patients with squamous carcinoma of the larynx and age- and sex-matched controls, 33 with laryngeal can­ cer, but only 3 controls, gave a history of occupational exposure to asbestos.32,58 This difference was striking, and the suggested increased risk has since been confirmed by similar case-control studies,59 and studies of occupational cohorts.60,61 25 DPMC-01533 LAM 008049 Digestive System Cancer An excess risk of cancers of the digestive system attributable to occupational asbestos exposure has been suggested by a number of epide­ miological studies.25,34,35,60,62-69 ^ major problem with these studies has been the inclusion of peritoneal mesothelioma cases among all observed cases, making it difficult to document an increased risk of any one digestive system cancer independent of that for mesothelioma. In occupational cohort mortality studies where peritoneal mesothe­ liomas were separated from other cancers of the digestive system, excess cancers of some sites have been observed. Among 933 amosite asbestos factory workers who were first employed between 1941 and 1945, there were 11 deaths from stomach cancer by 1971 (vs. 4.58 expected); 15 deaths from cancer of the colon or rectum (vs. 7.05 expected), and none from cancer of the esophagus (vs. only 1.23 expected).25 of 1.779 deaths through 1974 among a cohort of 17,800 insulation workers there were observed 15 deaths from oropharyngeal cancer (vs. 7.87 expected); 14 deaths from cancer of the esophagus (vs. 5.35 expected); 18 from stomach cancer (vs. 11.23 expected), and 47 from cancer of the colon or rectum (vs. 28.63 expected).25,60 other studies of groups exposed to asbestos examining the risk of these specific cancers after excluding mesotheliomas are needed to further elucidate the role of asbestos in cancers of the digestive system. Other Cancers Studies of women asbestos workers have suggested possible increases in cancers of the ovary and uterine cervix. Among a group of female English asbestos worker, 4 and possibly 6 deaths from ovarian cancer were observed while only 2.1 had been expected.55 Investigators from the Soviet Union have reported significantly increased rates of cervical cancer among older female asbestos workers; however, the numbers of per­ sons in the study populations were not indicated.55 Findings in these reports need confirmation elsewhere. Association of Effects with Fiber Type There are few studies of persons exposed to a single type of asbestos, and the studies that are available often lack information on potential confounding factors such as cumulative exposure, smoking history, and physical characteristics of airborne fibers. It is there­ fore exceedingly difficult to assign a scale of relative pathogenicity to different types of asbestos. For example: • Crocidolite mined in the Northern Cape Province of South Africa and in Western Australia is frequently associated with pleural mesotheliomas, whereas fewer cases have been reported for crocidolite from the South African Transvaal. 26 LAM 008050 It has been proposed that this apparent difference in risk may relate to a difference in physical characteristics of fibers from these areas—crocidolite fibers from the Transvaal are thicker and longer.^ • As asbestos proceeds from mine to mill to manufacturing plant, it can become subdivided (and fractured), pro­ ducing fibers of smaller diameter and length, with pos­ sibly greater or smaller attendant biological risk. • Asbestos thought to be of one type may be "contaminated" with asbestos of another type. Lung tissue from men employed in Canadian chrysotile mining has been observed to contain tremolite and other amphiboles, often more than the amount of chrysotile. All types of commercial asbestos have been related to high rates of lung cancer in asbestos workers, and in occupational groups exposed to chrysotile, crocidolite, and amosite, pleural and peritoneal mesothe­ liomas have been observed.?2 Studies of anthophyllite miners in Finland have shown a slight excess of lung cancer, but no mesotheliomas.^6,37 The lack of mesotheliomas may be due to the small size of the cohort studied; however, none has been reported from the communities in the mining area.^ There is some information suggesting that chrysotile may not be as hazardous as other types of asbestos . 38,47,74-78 The mortality experi­ ence of a cohort of workers employed at an asbestos paper and millboard manufacturing plant that used only chrysotile asbestos would seem to bear this out.^9 Pleural and peritoneal tumors, as well as excess lung cancer, have been found in the mortality experience of workers who had mined and milled New York State talc.80,81 This talc may contain large quanti­ ties of tremolite asbestos as well as smaller amounts of anthophyllite and chrysotile. In Italy, where the talc is reportedly uncontaminated, mining and milling has not been associated with mesothelioma or excess lung cancer.82 Dose-Response Relationship Evidence that the risk of developing cancer is related to the degree of exposure to asbestos by some quantitative estimate strengthens the basis for assuming asbestos to be of causal importance. A precise dose-response relationship is difficult to establish for any environ­ mental exposure and no less so for asbestos. However, attempts have been made for asbestos and there is some evidence suggesting that dose 27 DPMC-01535 LAM 008051 as measured by severity of exposure and duration of employment relates to rates of cancer in groups occupationally exposed to asbestos. One study concluded that within an age cohort for which data were most accurate there was an increasing mortality due to lung cancer with increasing duration of employment.63 However, rates for individuals employed the longest were lower than those in the category of next greatest duration of employment; persons employed longest might more likely be those whose occupational exposure to asbestos was less intense or who were themselves less susceptible to cancer and respiratory dis­ eases (for example, persons who do not smoke). An investigation of mortality among workers at an asbestos textile factory in England found markedly reduced mortality from lung cancer, and from other diseases in the presence of asbestosis, with reduction in length of exposure before 1933.32 Moreover, the risk of lung cancer and mesothelioma among workers at a Londom asbestos textile and insulat­ ing materials factory was independently found to be related to the severity and duration of exposure.39,55,83 The respiratory cancer mortality (includes deaths due to pleural mesothelioma in addition to cancers of the lung and larynx) of a group of retired asbestos workers was categorized according to cumulative dust exposure. "Exposure" was the product of job-characteristic dust levels in millions of particles per cubic foot (mppcf) and number of years on the job, summed across all jobs held (thus giving cumulative exposure in mppcf-years). The result is shown in Table 5. It can be seen that there is a clear gradient of increasing Standard Mortality Ratio (SMR), or ratio of observed to expected deaths x 100, with increasing cumula­ tive dust exposure.^® Table 5 DEATHS FROM RESPIRATORY CANCER BY CUMULATIVE DUST EXPOSURE Total Dust Exposure (mppcf-yr) Number of Men Respiratory Cancer Deaths Expected SMR Observed Under 125 533 15 9.0 166.7 125-249 305 12 4.8 250.0 250-499 328 17 5.2 326.9 500-749 126 9 1.8 500.0 750 and over 56 5 0.9 535.6 Source: Chapter Reference 78. 28 DPMC-01536 LAM 008052 The Cancer Latency Period From all available evidence, the period between first exposure to asbestos and death from lung cancer appears to be related to intensity of exposure.84 Among workers at an English asbestos textile and insu­ lating materials factory, an excess mortality from lung cancer was demonstrated following a latency of 15 years for those with heavier exposures, whereas an excess did not appear until 25 years from onset of exposure for those whose exposures were less intense.39,61,83 Fifteen years is probably the minimum latency period for asbestosrelated lung cancer. An excess of lung cancer deaths first appeared among a group of heavily exposed amosite asbestos workers 15 years after onset of exposure,85 and in a large cohort of insulation workers fol­ lowed from 1967 through 1974 (135,000 person-years of observation), no applicable increase in mortality from lung cancer was observed before 15 years had elapsed from onset of exposure. The peak increase occurred about 30-35 years after onset of exposure.25 In 85% of one series of mesothelioma cases, death occurred more than 25 years after first exposure to asbestos, with a range of 3.5 to 53 years.86 Another investigator reported a mean latency period of 37 years,87 and among a large cohort of asbestos workers, most deaths from pleural and peritoneal mesotheliomas occurred 30-35 years after first exposure.25 Incidence of Cancer and Age at First Exposure to Asbestos A characteristic of many cancers is a marked increase in incidence with advancing age. It is generally acknowledged that the higher inci­ dence of cancer in older persons is not necessarily because their tis­ sues are more predisposed to cancer, but because of the usually long period between initial exposure and the appearance of diagnosable tum­ ors. 88 xn fact, with regard to susceptibility of body tissue to cancer, it has been hypothesized, from experimental animal evidence, that the tissues of younger people may be more susceptible to carcinogens but that, conversely, older people may be more susceptible to cancer because of a less efficient immune surveillance system.89 In a study of the relative incidence of lung cancer according to age at first exposure to asbestos, data were obtained on 117 men who were exposed for more than 20 years and who were followed for an average of 13 additional years. A greater incidence of lung cancer was observed among men first exposed at older ages. For those first exposed under age 25, the annual lung cancer incidence was 26% of the rate for all ages; for first exposure between ages 25 and 29 it was 165%; at age 30+ it was 195%. These incidence rates were corrected to account for varia­ tion in the duration of exposure, duration of survival after first exposure, and for the fact that some lung cancers may have been due to 29 DPMC-01537 LAM 008053 nonoccupational causes more common among older men. The data suggested that susceptibility to asbestos-related cancer may increase with age.88,89 It seems unlikely, however, that age per se is a principal factor in determining frequency of cancer, and it is not clear whether age itself plays a part that is independent of exposure duration and time elapsed since first exposure. Smoking and Asbestos-Related Cancer* • There is strong evidence that cigarette smoking alone is sufficient to cause lung cancer. Many studies attempting to examine the effect of cigarette smoking on the increased risk of lung cancer observed in groups exposed to asbestos have been deficient in one or more of these respects: • Follow-up periods have been too short to allow accurate computation of risk after the necessary 15-20 year latency. • Nonsmoking asbestos-exposed groups have been very small. • Smoking habits have not been completely ascertained. • Smoking-adjusted mortality rates from the general population have not been used for comparison. A few studies have found that cigarette smoking was insufficient to account for the increased risk of lung cancer among asbestos workers. This has been generally accepted as evidence that asbestos can act independently to cause lung cancer, a view that has been corroborated by animal experiments and by some evidence suggesting an increased risk among nonsmoking asbestos workers.82 An investigation of two groups of asbestos workers—one with a high dust exposure and a high respiratory cancer mortality, the other with a lower dust exposure and a lower respiratory cancer mortality—found that their smoking habits were similar.This implies that high doses of asbestos can account for higher mortality among smokers. Another inves­ tigation, a case-control study of lung cancer patients, revealed an enhanced risk of lung cancer with asbestos exposure, whatever the number of cigarettes smoked.82 In a study of the combined effects of asbestos exposure and smoking, the smoking habits of 1,334 male and 482 female asbestos factory workers were examined in relation to mortality from lung cancer over a 10-year period. Among 955 smokers with severe asbestos exposure, 41 lung cancer deaths were observed, while only 11.3 were expected for smokers from the general population. Among 161 never-smoking asbestos workers with 30 DPMC-01538 LAM 008054 ■jll severe asbestos exposure, 1.7 lung cancers deaths were observed, while only 0.2 were expected for nonsmokers in the general population. There were approximately five times as many person-years of observation in the smoking group compared with the nonsmoking group, but about 24 times as many lung cancer deaths among the smokers.90 In another study, smoking histories were obtained from 11,657 of a cohort of 17,800 insulators. In 9,591 workers with a history of ciga­ rette smoking, 248 lung cancer deaths were observed, compared with 59.5 expected. Among 609 workers who had smoked pipes and/or cigars, two lung cancer deaths were observed and 1.24 were expected. Of 1,457 workers who never smoked regularly, four lung cancer deaths were observed, while 1.08 were expected.25 Expected deaths were based on approximate smoking-specific U.S. death rates. Further analyses of group data have been performed to examine how cigarette smoking and asbestos might be acting together.91,92 on a statistical basis it appears that these two independent causes of lung cancer interact positively. In the general population, cigarette smokers have a 10-15-fold excess risk of lung cancer. One study observed an 8-fold excess of lung cancer among smoking asbestos workers compared with smokers in the general population, but the excess was 92-fold when com­ pared to the general population of nonsmokers.92 This suggests that the combined effect of smoking and asbestos exposure is greater than the simple sum of their separate effects. The relation of this statistical interaction to the pathogenesis of lung cancer is uncertain. However, it seems clear that, due to the important enchancement of risk by one cause complementing the other, the increased risk of lung cancer in groups exposed to asbestos may be concentrated among those who also smoke. There is very little evidence that cigarette smoking increases the frequency of developing pleural mesothelioma after asbestos exposure, and no evidence exists that smoking increases the risk of peritoneal mesothelioma. Of 9,951 insulation workers with a history of cigarette smoking, there were 23 deaths from pleural mesothelioma and 47 deaths from peritoneal mesothelioma, with none expected. Among 1,457 workers who never smoked regularly, there'were two deaths from pleural meso­ thelioma, eight deaths from peritoneal mesothelioma, and none expected.25 Cancer from Incidental Occupational Exposure Persons who do not work with asbestos directly, but who may be incidentally exposed to asbestos while working, may suffer excesses of cancer. A 10% random sample of shipyard workers, widely distributed *This is an adjusted figure to compensate for missing smoking infor­ mation for the deceased. 31 DPMC-01539 LAM 008055 throughout the various trades, revealed that some had pleural plaques and some had pulmonary fibrosis, and retrospective and prospective cohort mortality studies have revealed a 2.5-fold excess risk of lung cancer as well as a number of mesotheliomas among workers with pleural plaques. Even those without X-ray evidence of exposure to asbestos had a slightly increased risk of lung cancer and a few mesotheliomas. A study of sheetmetal workers also revealed a small excess of lung cancer and one mesothelioma.93-95 Disease in Workers' Households There are presently 37 reported cases of mesothelioma in persons whose presumed exposure to asbestos was limited to living in the homes of asbestos workers.96 However, no comprehensive studies of the dis­ tribution of mesothelioma by age and sex among contacts of asbestos workers in their homes have been conducted. The majority of reported mesotheliomas related to household exposure have been in women, perhaps because they are more likely to be exposed to asbestos by washing the garments of asbestos workers.96,97 Thirty-five percent of examined family contacts of asbestos workers were found to have radiological abnormalities characteristic of asbestotic disease.72,96 Cancer in the Neighborhood of Asbestos Facilities On the basis of numerous anecdotal reports, indirect assessments, and case-control studies, there seems little doubt that both pleural and peritoneal mesotheliomas may result from some types of residental expo­ sure to asbestos.45,48-50,74,86,98-103 However, there have been no adequate population-based studies, and an accurate estimate of risk, where occupational and household exposure are definitely excluded, cannot be made. On the basis of one case-control study of mesothelioma patients, relative risk of mesothelioma was estimated at 2.1 for residentially exposed, and 4.3 for occupational exposed, persons.^9 Two studies have been made of the possible effects of increased asbestos contamination of drinking water in Duluth, Minnesota, due to the disposal of taconite tailings into Lake Superior. No carcinogenic effects have been noted, but the period of observation was short rela­ tive to the probable latency period of environmentally-induced can­ cer. 104, 105 Carcinogenic Effects—Animal Studies All commercial types of asbestos—chrysotile, crocidolite, amosite, anthophyllite—have been found to be carcinogenic when tested in mice, rats, hamsters, and rabbits. A brief review of evidence derived from 32 LAM 008056 experimental observations is presented below for its value in corrobo­ rating known human cancer risks, predicting other effects, and increas­ ing the plausibility of certain hypotheses on causal mechanisms. A more detailed treatment of these and other relevant studies in animals can be found in Appendix D. Intrapleural or intraperitoneal injection of asbestos has produced sarcomas* and mesotheliomas. Laboratory animals have not been known to develop mesotheliomas spontaneously, so that finding even a single such tumor in an experiment may be significant. Rats and rabbits receiving intrapleural injections of crocidolite developed pleural mesotheliomas, as did rats receiving chrysotile.106 por both these fiber types the carcinogenic response appeared to be dose-related in another study with rats.10? Mesotheliomas have also been induced in rats by Russian chrysotile-LO^ and in hamsters by various types of asbestos fibers.109 Peritoneal mesotheliomas were observed in rats following intra­ peritoneal injections of chrysotile and crocidolite but not amosite.106 Rats that received intraperitoneally chrysotile milled to 99% <3 pm also_ developed peritoneal tumors.HO Mesotheliomas were induced in rats inoculated with crocidoliteHl and in mice inoculated with chrysotile, crocidolite, or glass fiber. H2 ' Lung carcinomas and pleural mesotheliomas have followed from the inhalation of asbestos. Rats exposed to various doses of chrysotile, crocidolite, and amosite have developed malignant tumors of the lung and of the mesothelium.106>H3-115 Among these studies, adenocarcinoma, squamous cell carcinoma, and fibrosarcoma were reported. Among groups of rats that were exposed with varying durations to five different types of asbestos fibers, all of which produce asbestosis, a dose-response relationship for malignancies was suggested.6 In this study it was observed that as little as one-day exposure was sufficient to produce tumors. | Few data exist about the effects of asbestos administered orally. One study found that oral administration of asbestos filter material to rats led to an increased incidence of malignant tumors.H6 Car­ cinomas of the lung, kidney, and liver, as well as reticulum-cell sarcomas, were found. [ } The available evidence from animal studies relating asbestos type to differences in carcinogenic potency is limited and inconsistent. This may be due to the predominant influence of size and shape of fibers, which may vary from one study to another for each asbestos type. Min­ eral fibers other than asbestos, but of similar size, can produce mesotheliomas in rats after intrapleural or intraperitoneal injection.107> 117,118 Although the carcinogenic mechanism involving fibers has not 1 ' j ' * i A sarcoma is a malignant tumor derived from mesodermal tissue. 33 DPMC-01541 LAM 008057 i been entirely elucidated, a reasonable hypothesis is that it may be related to morphologic characteristics. There are few studies in which fiber size alone has been varied and adequately recorded (diameter as well as length). Furthermore, the preparation of fibers for experimental purposes may alter mineral properties.H9* However, smaller fibers are thought to be more active in producing tumors. Noncarcinogenic Effects of Asbestos Noncarcinogenic effects of asbestos exposure were noted several decades before the association between asbestos and cancer was recog­ nized. In 1906, deaths among asbestos textile workers from penumoconiosis were reported in England and France.121,122 These were the first reports in modern times of the diffuse interstitial fibrosis of the lung associated with asbestos exposure—"asbestosis." Asbestosis Asbestosis, which is characterized by a diffuse interstitial fibro­ sis of the lung, is one of the many dust-related lung diseases that are terminal pneumoconioses. However, unlike some of the other pneumo­ conioses, asbestosis does not predispose to the development of pulmon­ ary tuberculosis, nor does evidence suggest that it is causally related to emphysema and chronic bronchitis.123 Clinical Findings The signs and symptoms of asbestosis, listed below, are no different from those for other forms of diffuse interstitial fibrosis; there are no pathognomonic features. Symptoms: • Breathlessness on exertion • Cough, usually dry, but may be productive • Chest tightness or pain * Ball milling of chrysotile, for example, can result in decreased crystallinity and changes in interlayer branching and surface hydroxyl configuration. These alterations have been accompanied by decreased hemolytic activity.120 34 LAM 008058 Signs: • Decrements in lung function (decrease in lung volume and flows) • Radiographic abnormalities (chest) • Rales, basilar • Restricted chest motion • Clubbing of fingers • Cyanosis • Cor pulmonale (right ventricle hypertrophy) • Pleural effusion. The earliest and most prominent clinical finding—breathless­ ness on exertion—rarely becomes apparent until after at least a decade of exposure. Thus, by the time this "early" clinical finding appears, the underlying disease process is well under way. As the disease pro-gresses, breathlessness may be present even at rest. The most characteristic physical sign exhibited by the patient with asbestosis is the presence of dry, crackling sounds (rales), heard on auscultation at the lung bases and in the axillae during inspiration. As fibrosis progresses, rales become more widespread and occupy a greater part of the inspiratory cycle. Clubbing of the fingers is usually a late feature of asbes­ tosis and is not found consistently. Cyanosis of the skin and mucous membranes of the mouth and tongue may also occur in the later stages of the disease. Radiographic Abnormalities Radiographic features of asbestosis are similar to those of other forms of diffuse interstitial fibrosis of the lung, except for the frequency of pleural changes, expecially pleural plaques (which should ' always signal the possibility of asbestos exposure). Radiographic diagnosis of asbestosis is based on the presence of small, irregular, or round opacities distributed prominently in the lower lung fields. The earliest changes often occur bilaterally in the cosophrenic angles. Short, horizontal, linear septal lines (Kerley B-lines), which are believed to represent lymphatic obstruction,^ may also be present. With time, the abnormal shadows gradually spread upward into the middle and upper zones of the lung fields and become increasingly coarse and blotchy. In more advanced cases, a "honeycomb" pattern may be present. 35 DPMC-01543 LAM 008059 and the outline of the diaphragm and heart may become blurred and "shaggy." Pleural changes are likely to be present as well, perhaps in as many as 50% of the cases. Pulmonary Function Changes The interstitial fibrosis associated with asbestos exposure is accompanied by changes in pulmonary function characteristically observed with interstitial fibrosis from other causes as well. Thus, while these changes are not unique to pulmonary asbestosis, they provide useful diagnostic information when interpreted together with other evidence such as exposure history, signs and symptoms, and chest radiographic findings. Changes in pulmonary function considered most characteristic of asbestosis are: • General reduction of lung volume, especially of vital capacity (VC) • Decrease in pulmonary flow rates such as indicated by forced expiratory volume in one second (FEV^ q) • Impaired alveolar-capillary diffusing capacity, reflected by reduced oxygenation of the arterial blood and increased alveolar-arterial PO2 gradient (alveolar-capillary block syndrome). Although it is usually claimed that airway obstruction is rarely a major feature of asbestosis,123-125 one investigator has pointed out that epidemiologic studies of lung function have been unable to clarify the relationship between obstructive airway disease and asbestos exposure. She advised that, until further evidence becomes available, "an open mind should be kept in this regard."54 Asbestosis and Cancer On the basis of case reports, an association between asbes­ tosis and lung cancer was suspected as early as the 1930s. re than a decade later, two authors!26,127 reported that, among British asbestos workers, carcinoma of the lung and pleura had been found in about 15% of deaths either caused by asbestosis or in which asbestosis had been proved present at autopsy.* By the period 1961-1963, figures from the British Ministry of Labour showed that approximately 50% of patients certified as suffering from asbestosis (in contrast to exposed to It remained for another investigator to show that the actual risk of dying from lung cancer was increased on the order of 10-fold over the general population for male asbestos workers employed for 20 years or more between 1922 and 1953. 36 DPMC-01544 LAM 008060 asbestos) died of (or with) lung cancer. Although carcinoma of the lung is often found in the presence of asbestosis, there appears to be no scientific evidence that the two lesions are interrelated, except that they both may be classified as diseases that are causally associ­ ated with exposure to asbestos. With regard to another asbestos-related cancer, two reviewers of the subject have noted that mesothelioma of the pleura and peritoneum has often been associated with even low levels of asbestos exposure for brief periods in the remote past.54,123 There appears to be no regular correlation between severity of asbestosis and occurrence of mesothe­ lioma. In fact, it is unusual to find significant pulmonary interstitial fibrosis (asbestosis) with pleural mesothelioma. However, prominent asbestosis is frequently observed in association with tumors of the peritoneum,54,123 and peritoneal tumors generally appear to be associ­ ated with heavier asbestos exposure.45,130 One reviewer noted that this appears to support the notion of retrograde lymphatic spread of asbestos fibers from the lung to the abdominal lymphatics resulting from thoracic lymphatic obstruction due to advanced pulmonary fibrosis.54 Asbestos Pleural Effusion Benign pleural effusion, which usually occurs in the presence of some degree of parenchymal asbestosis, is another clinical manifesta­ tion of disease due to asbestos exposure. Among a series of 57 patients with asbestosis or asbestos exposure, 12, or 21%, were found to have "asbestos pleural effusion"—i.e., a pleural effusion in an individual with a history of occupational exposure to asbestos in the absence of any other disease known to cause pleural effusion.151 a number of individuals diagnosed as having had asbestos pleural effusion have sub­ sequently developed mesothelioma.132,133 Pleural Calcification, Diffuse Fibrosis, and Plaques Asbestos-related plaques occur as discrete, elevated, grey-white lesions on the inner surface of the rib cage and on the diaphragm. ■k The reason for this apparent increase in the percentage of deaths in which asbestosis and lung cancer were found on autopsy is not clear. One explanation may be that the cases described by earlier authorsl26,127 received much of their asbestos exposure in the early quarter of the centruy, when it was likely that airborne concentra­ tions of asbestos were high. As a result, many of these cases may have succumbed to asbestosis at an early age—before lung cancer, with its long latent period, could develop.128,129 37 DPMC-01545 LAM 008061 Microscopically, the plaques consist primarily of connective tissue, often containing deposits of calcium. They do not interfere with pulmonary function to any significant extent, nor do they necessarily indicate the presence of pulmonary fibrosis. An association between pleural abnormalities and exposure to asbestos—both occupational and nonoccupational—has been clearly demon­ strated. 54,123,134-139 Accordingly, their presence should always alert the examiner to the possibility of asbestos exposure. In this regard, it may be 20 to 40 years after exposure to asbestos that pleural calcifications appear radiographically.335 Although pleural plaques do not, themselves, appear to be precur­ sors of malignant disease, a retrospective death-certificate study of 408 shipyard workers with pleural plaques showed that the risk of developing bronchial carcinomas was increased by a factor of 2.4.95 Three cases of mesothelioma also occurred in this series. In a pro­ spective study from the same shipyard, 235 men with radiographic evi­ dence of pleural plaques were found to have a 2.4-fold increased risk of bronchial carcinoma. Among 70 deaths, 13 were due to mesothelioma, an excess of obvious significance.94 Asbestos Warts Asbestos warts, or corns, are of minor health significance, but they are an indication of exposure to asbestos. They are caused when asbestos fibers penetrate the skin and are most often found on the hands and forearms.140 The warts may have a pinpoint, black center and are often tender to pressure. Unless removed by excision, they may persist for years. Animal Studies—Evidence of Noncarcinogenic Effects Exposure by inhalation to any>of the four commercial asbestos types may result in fibrosis of the lungs in animals as well as in humans.bl­ under experimental conditions a fibrogenic response to inhaled asbestos has been reported in rats, hamsters, guinea pigs, rabbits, and mon­ keys. 142-144 Outside the laboratory, pulmonary fibrosis in the presence of fibers and asbestos bodies has been demonstrated in baboons, donkeys, and wild rodents living in the vicinity of crocidolite mines or mills.145 Pulmonary asbestosis has also been reported in a dog kept as a rat catcher in a London asbestos factory.146 There are marked interspecies differences in susceptibility to asbestosis. Tissue reaction in rats, rabbits, and monkeys is typically less severe than in hamsters and guinea pigs.342,14/ 38 DPMC-01546 LAM 008062 I Subcutaneous injection of asbestos or injection into the pleural or peritoneal cavities produces a fibrotic reaction. Thickening of the pleural, pericardial, and peritoneal membranes has been reported, with formation of adhesions and granulomas as well as pulmonary and media­ stinal abscesses. Neither shape nor chemical composition is sufficient to explain the fibrosing effects of asbestos. Fibrosis has been induced with a variety of fibrosis as well as nonfibrosis mineral dusts. Some investigators feel that fibers are more fibrogenic than nonfibrous particulates and that fibrogenic reaction increases with increasing fiber length. How­ ever, the role of fiber length is difficult to evaluate without simul­ taneously taking into account possible effects of diameter and aspect ratio (length/diameter). On injection, chrysotile heated to 400°C caused fibrotic reaction in the pleura of mice equivalent to that of unheated chrysotile, but fibrosis production diminished as temperatures increased above 400°C (at 600°C, 800°C, 1000°C). Asbestos in dust from automobile brake linings, which are subjected both to high temperature and mechanical grinding, resembled chrysotile that had been heated to 800°C or more and then ground.^ Effects of asbestos that may be related to fibrogenesis have been observed iai vivo in mammalian tissues as well as in cell culture. Bio­ chemical changes, including stimulation of anaerobic metabolism, and physical effects such as damage to cell membranes and chromosomes have been noted.*150-158 k Such observations may shed light on the mechanisms by which asbestos induces fibrosis. For example, it has been postulated that during phagocytosis, asbestos causes damage to the membranes of macrophage lysosomes, which are cell organelles that contain lytic enzymes. Sub­ sequent intracellular release of these enzymes may injure or kill the macrophages, resulting in release of a fibrogenesis-stimulating factor.159 39 DPMC-01547 LAM 008063 Chapter IV OCCUPATIONAL EXPOSURES There is little recent data in the published literature on expo­ sures to asbestos, and it is difficult to assess whether what has been published is typical. Furthermore: • Occupational asbestos concentrations are commonly reported as optical-microscope-visible fibers per milliliter greater than 5 im long, and these may account for only a small fraction of the total electron-microscope-visible fibers • It is not known whether small differences in fiber counts actually reflect differences in fiber levels or, if they do, whether they indicate a change in the risk of incurring asbestos-related diseases (see Appendix C). Nevertheless, quantitative air sampling data from representative occupa­ tions is provided in this chapter in an attempt to indicate the range of exposures found in three workplace situations: asbestos mining and milling, production and processing of asbestos products, and utiliza­ tion of asbestos-containing products. Fewer than 600 persons in the United States are employed in mining and milling asbestos.* However, industries that manufacture asbestos products or that make use of them provide jobs for millions. These industries may be categorized as primary, secondary, or consumer accord­ ing to whether they produce manufactured goods from raw asbestos fiber, process asbestos manufactured products to make other products, or utilize a finished product containing asbestos without additional modi­ fication. Over 37,000 persons are employed in the manufacture of primary asbestos products; 300,000 are employed in secondary asbestos industries; and millions more work in the asbestos consumer industries—over 185,000 Many more may be exposed to asbestos as a contaminant during the mining and milling of other minerals. 41 DPMC-01548 LAM 008064 of them in shipyards and almost 2 million in automotive sales, service, and repair.1 Exposures in Mining and Milling Sources of asbestos exposure in mining and milling include blast­ ing, crushing, transporting, and drying ore; air-aspiration milling; and disposing of waste. Time-weighted-average (TWA) levels of fiber in mining reported in 1973 ranged from 0.5 to 2.8optical-microscope-visible (o-m-v)* fibers per milliliter, with an average of 0.9. Much higher concentrations were found in milling, where exposures ranged from 6.0 to 12.1 fibers per milliliter.2 In addition to mining and milling of asbestos, the mining and mill­ ing of other mineral ores that may contain asbestos as an impurity is a potential source of asbestos exposure. For example, concentrations of asbestiform fiber in one hard-rock gold mine were reported in 1976 to average 0.25 o-m-v fibers per milliliter, ranging up to 2.8,3 ancj fiber counts of 8 to 260 per milliliter were recorded in a talc mining and milling operation, according to a 1973 report.^1 Exposures in the Asbestos Products Industries For all segmerits of the primary industry, manufacturing begins with fiber receiving and warehousing. Levels of airborne fiber in these areas have ranged from 0.2 to 2.5 o-m-v fibers per milliliter and are typically about 1.0.+ Levels at the upper limit of the range reflect damaged shipments, careless unloading or ineffective housekeeping. The most important factor influencing asbestos exposure at this step of production is the condition of the bags in which asbestos is shipped. Next, asbestos fibers are introduced into the process. Bags of asbestos are usually cut open and dumped manually, either into open hoppers or into bag opening enclosures. This activity can result in relatively high exposures if hooding is inadequate or lacking. Disposal of the emptied bags may also add to airborne fiber levels. In four of the seven major primary industries, highest TWA exposures occur in fiber introduction and have ranged from 0.3 to 10.0 o-m-v fibers per milli­ liter, typically somewhat above 2 fibers. Exposures in mixing and blending depend upon how dry the materials are that are being mixed, the intensity of agitation, and the effective­ ness of ventilation. Typical TWA values in the past have been Greater than 5 micrometers in length. "*Data in this section are from Chapter Reference 1 (published in March 1976) . 42 LAM 008065 approximately 2.2 fibers per milliliter, with a range of 0.2 to 10.0 fibers per milliliter. Sometimes asbestos is dumped directly from the bags into mixing or blending tanks, augmenting the usual exposures found at this step. Once the asbestos fibers are engulfed by a medium that prevents them from becoming airborne, exposures drop. This may occur at the step of mixing and blending—as in the production of floor tile, paper, and cement pipe—or in a subsequent step. Exposure levels in formulation operations have ranged from 0.2 to 22.0 fibers per milliliter, with an average level of 1.8 fibers per milliliter. This wide variety of exposures is due to the number of different processes represented by that stage. Finishing operations vary significantly from one type of industry to another, but usually include machining (i.e., cutting, drilling, grinding) the rough product to specification. The mechanical energy imparted 'during machining causes asbestos fibers to break loose and become airborne. Average TWA levels of exposure in these operations have ranged from 0.1 to 8.0 fibers per milliliter, with a mean of 1.6. In the last two production steps—inspection, and storage and shipping—asbestos exposures are usually the result of airborne dust generated by other operations, which may drift through the plant to these areas or adhere to the products themselves,- becoming airborne during handling. Exposures are typically less than 1 fiber per milli­ liter. Exposure levels in the major asbestos industries are summarized in Table 6 and are discussed below.^ Friction Products Friction products may contain 30% to 80% asbestos, and TWA exposures in the industry vary widely (0.1 to 15.0 o-m-v fibers per milliliter), averaging 2 fibers per milliliter for most operations. Greater concen-_ trations may occur in preforming operations, ranging from 0.5 to 22.0 fibers per milliliter and typically about 4 fibers per milliliter. The elevated exposure levels found in these operations result from manual handling of the dry preform mix (asbestos fibers and metal reinforcing materials in an organic matrix), which is conveyed in open carts, scooped by hand, weighed, and poured into a block mold for mechanical pressing into the shape of the finished product. Other operations that may yield high asbestos levels include fiber introduction, mixing of the dry preform, and finishing. During finish­ ing, the products are trimmed, drilled, sanded, ground, and sawed to specification. Exposures vary with work practices and equipment. For example, exposures at ventilated radial grinders are below 2 fibers per 43 DPMC-01550 LAM 008066 Table 6 EXPOSURE TO AIRBORNE ASBESTOS IN SELECTED ASBESTOS PRODUCT MANUFACTURING INDUSTRIES Asbestos Concentrations (Time-Weighted Average In Flbers/ml)a Operations with Highest Levels Most Operations Name of Typical Range Typical Range Operation(s) Number of Employees Production Workers Total Friction Products Primary 2 Secondary 0.1-15.0 4 0.5-22. 0 2.5-6.5 Forming or Rolling 4,900 Fiber Introduction 1,100 Fiber Introduction 900 7,300 34,500 Asbestos Paper Primary Secondary AsbestosReinforced Plastics Primary 1 2 0.3-2.8 1.0-3.5 1 Secondary Cement Pipe 0.75-2.7 0.2-2.5 2 0.5-3.0 0.5-2.0 4,500 198,000 2,600 11,000 1.5 0.25-3.5 2 0.6-4.5 Finishing 1,600 2 0.3-8.7 3 0.9-8.4 Dry Mixing, Sanding 600 2,400 Cement Sheet Primary Secondary Floor Tile 1.0-6.0 1,300 24,000 1 0.5-4.3 4 0.9-4.3 Fiber Intro­ duction 2,900 6,700 4 0.25-10 4 2.0-10 Carding 2,400 3,700 Textile Primary Secondary Paints, Coatings and Sealants 2.0-6.0 1 1.0-2.5 7,500 2.5 1.5-8.0 Fiber Introduction 350 3,000 a0p tica1-microscope-visible fibers, 5 um long or longer. Sources: Daley AR, Zupko AJ, Hebb JL: Technological feasibility and economic impact of OSHA proposed revision to the asbestos standard. Roy F. Weston Environmental Consultants-Designers, March 1976 (prepared for: Asbestos Information Association of North America). 44 DPMC-01551 LAM 008067 milliliter, but chamfers and backgrinders may cause exposures of 5-8 fibers per milliliter.5 If the finished products have not been cleaned of adherent particulates, exposures may be high during inspection (4-7 fibers per milliliter). Asbestos Paper Exposure levels in the asbestos paper industry vary with the asbestos content of the manufactured product, which can range from 5% to virtually 100%. Typical TWA concentrations in the primary industry average 1 o-m-v fiber per milliliter (range 1-3 fibers per milliliter) except in fiber introduction and stock preparation (wet blending), where concentrations typically average 1-3 fibers per milliliter and range up to 10. The lower concentrations are achieved in plants which use disintegrating, pulpable bags, thus obviating bag opening, dumping, and disposal. Since papermaking is a wet process, little asbestos dust exposure is realized after fiber introduction until the product is dried. Expo­ sure concentrations may then be elevated somewhat by the manual handling and mechanical modification (slitting, calendering, converting, etc.) needed to prepare paper sheet according to specifications. Asbestos-Reinforced Plastics The asbestos content of reinforced plastic is relatively small,^ and reported exposures in both primary and secondary industries are lower than in most other segments of the asbestos industry. TWA concen­ trations during most operations range from 1.0 to 2.5 o-m-v fibers per milliliter. Fiber introduction, dry blending, and handling of the blended mixture and preform are sources of moderate levels of exposure. After the preform has been remelted, the asbestos is bound tightly in the polymer matrix, reducing the potential for airborne release. Fibers may still break free, however, during finishing. Asbestos-Cement Pipe and Sheet Asbestos-cement products may contain 10% to 70% asbestos. Although more asbestos is used in manufacturing asbestos-cement pipe and sheet than any other primary asbestos products, relatively few workers are employed in these branches of the industry (3,600 total, 2,200 in pro­ duction) . 1 In asbestos-cement pipe factories, TWA fiber levels range from 0.5 to 4.5 o-m-v fibers per milliliter, averaging about 1.5. In the 45 DPMC-01552 LAM 008068 manufacture of asbestos-cement sheet, some fiber-introduction and dry­ mixing operations may yield higher exposure levels (0.3 to 8.7 fibers per milliliter) than in the manufacture of asbestos-cement pipe, because fiber may be introduced directly into the dry mixer. Once fibers are engulfed by the cement mortar during wet mixing, there is little oppor­ tunity for them to become airborne until finishing. Higher levels (averaging above 2 fibers per milliliter) may be found during cutting and machining in cement pipe factories; and sheet trimming and sanding present the highest levels of exposure in the asbestos-cement-sheet process, generally about 2.5 and 3.0 fibers per milliliter, respectively. Floor Tile Asphalt or vinyl asbestos floor tile contains 8% to 30% asbestos. Airborne TWA asbestos concentration ranges from 0.5 to 5 o-m-v fibers per milliliter. Typical concentrations are approximately 1 fiber per milliliter, except for fiber introduction, where concentrations of 4 fibers per milliliter are common. Once the asbestos is engulfed by the agglomerated plastic during the later phases of mixing, the potential for exposure is reduced significantly. Asbestos Textiles Levels of exposure in primary and secondary production of asbestos textiles vary directly with the asbestos content of the manufactured products but generally are higher than in any other asbestos industry besides milling. A typical TWA concentration of airborne fiber—i.e., for most operations—in the primary textile industry is 4 o-m-v fibers per milliliter (range 0,1 to 22.3 fibers per milliliter) except in the carding operation, where the typical concentration exceeds 5 fibers per milliliter (range 6.1 to 27.3). High asbestos exposures in the asbestos textile industry result from the processing of dry—or, at best, par­ tially damp—fibers, which are easily dispersed into the atmosphere. During carding, the vigorous manipulation of the dry fibers to separate and align them accounts for the particularly high concentrations observed at this step—even in the face of intensive efforts to achieve effective ventilation. The liquid dispersion method of asbestos textile manufacture, in which asbestos fibers are mixed in water with chemical dispersing agents, results in much lower exposure levels (less than 1 fiber per milliliter) than in conventional plants.6 Moreover, the use of asbestos textiles 46 DPMC-01553 LAM 008069 made from dispersed yarns results in significantly lower asbestos exposures to the user than from conventionally manufactured products.^ Exposures in the Utilization of Asbestos-Containing Products With two notable exceptions, the insulation trades and clutch and brake installation and repair, levels of exposures to workers in the consumer industries are generally very low. But although exposure levels are low, the vast majority of workers in the asbestos consumer industries, it is surmised, are less aware of the health hazards of asbestos than are workers in the production industries and may not utilize basic control methods to minimize risk. Insulation Trades* • Exposures in the insulation trades vary widely, but they include the highest occupational exposures and control is difficult. In the early 1970's, there were approximately 36,000 insulation installers® _ employed largely in insulating industrial equipment, commercial buildings, and ships. It is difficult to obtain characteristic exposure levels for these workers due to the many different insulating materials and condi­ tions of work. The asbestos content of materials in use ranges from 10% to almost 100%. Asbestos substitutes are gaining in use as regulations over the use of asbestos become increasingly more restrictive. Jobs performed by insulation workers can be classified into six categories: • Prefabrication: materials are precut and shaped using hand or power saws either on the job or at the con­ tractor's shop (10% of time). • Application: Materials are fitted, hammered, or carved and attached to surfaces by wiring or gluing (40% of time). Some materials used to be sprayed applied, but this practice has been virtually eliminated in recent years. • Finishing: Materials are coated with asbestos-containing cement, resin, asbestos or cotton cloth, or petroleum based sealer (30% of time). • "Rip-out": Removal of old or unusable materials in the process of reinsulating (10% of time). • Mixing: Mineral wool, asbestos, fiber glass, and cement or glue are mixed in buckets or troughs separately or in combination (5% of time). • Miscellaneous: (5% if time). Cleaning up, transporting materials 47 DPMC-01554 LAM 008070 Percent of time at each task is highly variable, of course, and intended only as a rough guide.9 Highest concentrations encountered by insulation workers have occurred during "rip-out" or removal of old asbestos insulations. In a 1968 report on air samples collected on a ship during removal of sprayed asbestos coatings, removal of 100%-asbestos lagging, and subse­ quent cleanup were said to average 248 o-m-v fibers per milliliter, 62-159 fibers per milliliter, and 353 fibers per milliliter, respec­ tively; in comparison, the application of pipe lagging containing 15% asbestos resulted in exposures of 5-60 fibers per milliliter, and cut­ ting and drilling incombustible board prior to installation yielded exposures of 0.7-4.5 fibers per milliliter.10 Levels of 30-100 o-m-v fibers per milliliter have been reported ruing application of spray asbestos insulation.H Nearby workers may be exposed to elevated levels of asbestos as the result of the activities of insulators— especially in shipbuilding, where work often goes on in enclosed poorly ventilated spaces. Brake and Clutch Repair There are almost 2 million persons employed in automotive sales, service and repair, of whom 900,000 are said to be frequently exposed to asbestos from automotive brake and clutch repair.1 (Note that this figure does not include persons who repair other kinds of brakes and clutches.) Asbestos exposures were determined for specific brake servicing operations including blowing-out automobile brake drum assemblies, grinding used truck brake linings, and bevelling new truck brake linings. Average peak o-m-v asbestos air concentrations for these activities based on sampling within 10 feet of the operator were 10.5, 3.75, and 37.3 fibers per milliliter, respectively.12 In a similar study, mean concentrations found 3-5 feet, 5-10 feet, and 10-20 feet from an operator blowing dust out of brake drums were 16.0, 3.3, and 2.6 fibers per milliliter. Grinding truck brake shoes gave average concentrations of 4 fibers per milliter, and bevelling produced an average count of 37 fibers per milliliter. Measurable con­ centrations (0.1 fibers per milliliter) were found at distances up to 75 feet from the blowing-out operation (14 minutes after), 60 feet from grinding, and 30 feet from bevelling, indicating that other garage employees besides those directly involved in brake and clutch repair are at risk.13 Another study estimated the time-weighted average exposure for brake mechanics to be 0.8 o-m-v fibers per milliliter.14 Installation of Floor Tile, Roofing, and Siding There is limited information relating to levels of exposure during installation of asphalt or vinyl asbestos floor tile. Because asbestos 48 DPMC-01555 LAM 008071 fibers are firmly imbedded in the tiles, installation per se is unlikely to be a source of important asbestos exposure. It is accepted practice, however, to sand old asphalt or vinyl tile floors before installing new covering. Conventional belt sanders with coarse grit are used to sand the tiles, and, normally, 240 to 250 square feet of tile can be sanded per hour. One report states that levels of 1.2 and 1.3 o-m-v fibers occurred during a simulation of normal sanding activities over a short­ term sampling period. It is likely that fiber levels fluctuate significantly depending on the age and condition of the tile being sanded, grade of sandpaper, speed of the sander, size of the workspace, ambient humidity, and quality of ventilation. Installing asbestos roofing and siding should result in exposures of lesser magnitude since these operations are performed outside. Use of Spackling, Patching, and Taping Compounds Asbestos may be a primary component of spackling, patching, and taping compounds used in wallboard construction to finish joints and repair damage, or it may be a contaminant of talc, limestone, or other rock used as raw material. Used mostly in the construction industry, the compounds are also used by persons doing their own construction and repair, and intermittent exposure to asbestos may occur during mixing, application, and sanding (finishing). f To determine possible exposure during application, air samples were collected at various jobs and sites. Peak airborne asbestos concen­ trations measured during such operations as hand sanding, pole sanding, mixing of dry spackle with water, and sweeping-up averaged 2.3 to 47.2 optical-microscope-visible fibers per milliliter.16 All exceed the current OSHA occupational standard for an 8-hour time-weighted-average (2 fibers per milliliter), and many exceed the permissible ceiling (10 fibers per milliliter). Wearing Asbestos Garments Tests of wearing asbestos garments have indicated that breathing zone concentration can exceed 2 o-m-v fibers per milliliter. At one plant where hoods, coats, mittens, and leggings were worn, concentra­ tions of airborne asbestos fibers ranged from 9.9-26.2 fibers per milli­ liter, and the 8-hour time-weighted-average concentration was 4.7 fibers per milliliter.1? Exposures from wearing fire-fighting helmets also have been mea­ sured. A new helmet with an unlined asbestos cover, an identical older helmet, and a helmet covered with aluminized asbestos cloth produced breathing zone concentrations of 2.3, 1.4 and 0.0 o-m-v fibers per milliliter, respectively.-'-® 49 DPMC-01556 lam 008072 Chapter V NONOCCUPATIONAL EMISSIONS AND EXPOSURES Persons not employed in asbestos-related occupations are exposed to asbestos fibers that originate from natural sources or from mancreated sources such as the manufacture and use of asbestos products. Such asbestos may be inhaled—as, for example, in an office building in which the air is contaminated by asbestos insulation—or it may be ingested with water, food, and drugs. As would be expected, the further one gets from the occupational environment, the fewer data there are on such exposures—termed "nonoccupational" exposures. However, the avail­ able data are reviewed here to provide at least some indication of ppssible general environmental contamination. (See Appendix C for a discussion of the difficulties in measuring asbestos contamination.) Asbestos Emissions from Natural Sources Rock that contains asbestos can be disturbed by natural means, such as weathering or landslides, or inadvertently by such human interven­ tions as road building, construction, and tilling of the soil. In such cases, free asbestos fiber may be deposited onto soil or enter air and water,-'- thereby contributing to levels of contamination in the ambient air and in water as discussed in this chapter. The occurrence of rock formations that could possibly contain asbestos was discussed in Chapter I of this monograph, and the geograph­ ical distribution of such rock formations in the United Stated is shown in Figure 1. If the primary areas of source rock are looked at in conjunction with high population density, the most critical areas for emissions from natural sources appear to be eastern Pennsylvania, south­ eastern New York, southwestern Connecticut, and greater Los Angeles and San Francisco. Asbestos Emissions from Human-Created Sources Human-created sources of nonoccupational exposures to asbestos include the mining and milling of asbestos; the transportation of asbes­ tos materials and products; the manufacture, installation, use, and demolition of asbestos products; and the disposal of wastes. Some gross estimates of annual emissions in the United States from asbestos mining and milling, manufacturing, use of asbestos 51 DPMC-01557 LAM 008073 products, and disposal of wastes have been made and are shown in Fig­ ure 2. Although these estimates are uncertain, by at least an order of magnitude, several important conclusions are indicated: • Asbestos is preponderantly disposed to land, least to water. • Most of the asbestos disposed to land is consumer waste, which is more likely to be disposed to uncontrolled waste dumps and handled by persons unaware of the hazards. • Disposal to land is an important source of atmospheric asbestos and, because of proximity to urban popula­ tions, may be even more significant to health than the emissions to air that come from mining and milling. Redistribution and Fate of Asbestos in the Environment Because asbestos is exceptionally resistant to thermal and chemical degradation, it persists in the environment and can be widely redis­ tributed by both natural forces and human means. The magnitude of this redistribution is governed by an extraordinarily complex set of factors which include the height of the emission source, the rates of air and water flow, fiber diameter, rain, thermal air inversions,, electrostatic forces, agglomeration of particles, and the density of vehicular traffic on asbestos-containing landfill, to name only a few. Redistribution by Air If, for example, asbestos is emitted to air as part of a "large" agglomerated particle, it will settle to earth relatively quickly and thereby have a limited potential for environmental contamination; thus, concern over the relatively large quantities of asbestos emitted to air from mines is somewhat attenuated by knowledge that the mining processes tend to produce relatively large particles. At the same time, however, an appreciable fraction of the large mass of asbestos dis­ charged by mills is in the form of free fibers that may remain in the atmosphere for long periods of time, travel great distances, and expose many people. Studies of atmospheric pollution in the area surrounding asbestos mines and mills in Finland showed small amounts of asbestos dust as far away as 27 kilometers.2 A simplified calculation of "drift distance" for two sizes of ^ asbestos fibers was made for this monograph using the method of Cowherd and a terminal settling velocity as determined according to Harris.^ Fibers were presumed to be injected at a height of 50 feet (15.2 meters) 52 DPMC-01558 LAM 008074 J i i i M ii i . - g "I s K 5 9 8 S r S 2 : ; i R i i i Rj S : f * 1 ft * " R• 5 S * ~ I i • l 2 S I $ S 8 5 % u II ? ? f. = g 8 s ? 3 5 ? 51 i E S I 2 * £ ? i g ; S IJ 8 i i i i i i si 8 8 * 5 5 * a ■’ R * S " " 8 ft 2 2 ? R SIMs* 5 s ■a • s 8 s " " 2s. s? n= R «i 5* 8 n, U! 8ft ! S $S 44 X> 4—1447 li i I l f I hi *ii* %£ ‘8 i If i 1 Ml III i 18-! S til | -ij|f. 15 ll-^i I ?8 A ■is -iiE- "S! R I'k .Is. [I -* all |8 9* 5 ■| FIGURE 2 ■ IS. f5 *ism ^ - 4| •I t |g 8 15 .He. jj: : x• ~'l| -*S- :x ii l I I 5* * i <8 I * -li! -fis­ ts. NOIlOAOOtM DISPOSALS AND EMISSIONS OF ASBESTOS FROM ASBESTOS PRODUCTION, MANUFACTURING, AND CONSUMPTION IN THE UNITED STATES* {Metric Tons) 5 r * i i *f < ! 5 i III! 3 5 I | M0«i.«wnsN03 0N15 Exposure to Asbestos *It is to asbestos. one of mines per -'•’bic meter the possible routes by which humans Contamination of known that occupants elevated rates 70 nanograms in Drinking Water Drinking water is exposed to of households of asbestosis and are drinking water may be due partly of asbestos workers have mesothelioma.36 62 DPMC-01568 LAM 008084 to erosion from natural deposits containing materials viously in this Environment"). found chapter of serpentine and other asbestos- throughout the United States, as noted pre­ ("Redistribution and Fate of Asbestos Substantial contamination may also result disposal of asbestos wastes. These wastes directly discharged into water systems, atmosphere or disposed of on land may be effluents or in that are they may be released and subsequently join the from improper to the the water system. Another potential contaminator of drinking water is and pumping of municipal water distribution systems. miles of asbestos-cement and the pipes provide erosion.'>38 Gaskets pipes are used to the piping About carry water 200,000 to U.S. consumers, a source of asbestos fibers from leaching and and insulation used in treatment and in pumps are other possible contaminators.*6 The major difficulties are discussed in determining the asbestos in Appendix C. Furthermore, available are for "grab" samples—samples are taken from one source at one ples represent supply over receive location and their water cal variations time. the characteristics of content of water the analyses a few liters The degree that of water to which are that grab sam­ of an entire municipality's water time could be questioned—some municipalities from several sources, can change For this monograph, most of the asbestos data on and seasonal and content climatologi­ of water.+ the concentration of asbestos in drink­ ing water were extracted from 9 different published studies, represent­ ing 105 water supplies in the United States.6>7>39-45 (See also Appen­ dix E.) An effort was A study of asbestos made to select data only concentrations for finished drinking in two water systems using asbestos- cement pipes revealed average increases of 0.074 and 0.004 micrograms of asbestos respectively per liter of water at the tap.7 Laboratory tests conducted by the EPA37 and Johns-Manville7 on sections of asbestos-cement pipe also have shown increased in water. However, a rei cat (February cant release of chrysotile asbestos to the action of "moderately In San Francisco, water from a reservoir that also high located lished in flows 1974 in found that in rainfalls followed by are resulting fiber supplemented by water the amount during periods Further, a study and mineralogical nature of the Duluth water supply an increase in from river runoff (Recall that showed higher asbestos the surrounding regions.) pended solids solids is in a chrysotile rock area. in Philadelphia and Atlanta water supplies river of from asbestos-cement pipe exposed from other sources is concentrations report showed no signifi­ agressive" water.38 the study mentioned previously counts 1978) is most of pub­ sus­ evident when heavy the amount and shore fiber of suspended erosion.39 63 DPMC-01569 lam 008085 water—some of the samples were taken from taps in the water supply system; others were studies in which electron-microscope measurements were made are included. The cities cities; in taken at municipal water stations. in the studies were not selected indeed, to be Also, only representative of U.S. some were selected because asbestos was suspected to be their drinking water. Chrysotile fibers, present in 56 of amphibole fibers, the 105 water supplies. vidual samples varied between the lower lion electron-microscope-visible fibers did Mass the samples range over 40). or both were found to be Fiber concentrations in indi­ limit of detection and 130 mil­ per liter asbestos (for only two cities concentrations in indi­ vidual samples varied between below-detectable and 800 micrograms liter (for only three cities did the samples range over 60).* Exposure to Asbestos Asbestos in Foods and Drugs contents to date, and asbestos in foods per of food and drugs have not been well-established the FDA has no regulations concerning the content of and nonparenteral drugs. Foods may be contaminated during their agricultural phase from asbestos in air and soil and a pesticide vehicle. well as from asbestos Uptake of impurities deposition of contaminated water directly by sprinkler irrigation, ture has been found contamination of mented. 46 Processed are possibilities, to substantiate them. food in the course of foods adhesives, rubber, talc used as onto and resins roots, as leafy surfaces but no published litera­ One instance of accidental transportation has been docu­ may become contaminated with asbestos water used in their preparation or which asbestos juices, sugar, in contaminated water by plant from the use of either asbestos from filters, in processing and packaging.47 Foods for filters are used may include beer, wine, liquors, fruit lard, and vegetable oil.48 Asbestos filters have also been employed to process cider, condiments, washes, syrups, tonics, and vinegar.49 The authors of one study electron-microscope-visible drinking water, mouth­ found between 1.1 and 6.6 million fibers and between 1.7 and 12.2 million per liter in U.S. fibers per and Canadian beer, liter in Canadian soft drinks. They also reported between 1.8 and 11.7 million fibers per liter in wines from various parts of the world.50 in another study, between 13.1 and 24.0 million fibers per liter were found in one * Some authors micrograms reported per liter, their data as and some fibers per liter, some reported reported both. 64 DPMC-01570 LAM 008086 manufacturer's gin; the water used between 3.3 and 8.7 million Any estimate of in fibers the processing of per the quantity of gin contained consumed with food must liter.51 asbestos be purely speculative since virtually no concentration data have been reported. The FDA has certain foods Asbestos filters and blood plasma. less disapproved logies. Asbestos under ppb their use 1975, and which may their in as contain asbestos or as a the processing of noted in Chapter however, in I, drugs the and bio­ the manufacture of ingredients. capsules either directly as form release agent conditions in preparing parenteral drugs as an and in medicine and dentistry.53-55 foods, test and market asbestos.52 also have been used the manufacture of medicinal processed 10 filters may be used, nonparenteral drugs other uses that than But since April FDA has Talc, reported contained impurity, tablets Also, in found various talc may be added an ingredient or constituent has been used and has indirectly as to a of packaging materials.56-66 65 DPMC-01571 LAM 008087 Chapter VI CONTROL OF THE ASBESTOS HAZARDPHYSICAL CONTROL Three program approaches of asbestos following • fibers in man's two chapters. These the reducing approaches the the adverse health are presented in this effects and the are: Physical control of human exposure fibers—i.e., • for controlling environment to asbestos contact between man and fibers Medical surveillance—measures taken by and other health-care personnel physicians in behalf of asbestos- exposed persons • Education—ultimately, to asbestos fibers so of course, of persons exposed that physical and medical con­ trol measures will be of maximum effectiveness, but also to education of motivate responsibilities Reducing (1) actions practices; and other persons with contact between asbestos discussed engineering of for utilizing asbestos relate to are in a position for asbestos-control measures. the extent of be accomplished by include: persons who those who are exposed, in this the materials, commercially; (2) (4) control of emissions chapter includes processes, (3) facilities that improvement of work raw materials a section on the application of several specific manufacturing and and and asbestos wastes; asbestos and man can Such actions administrative measures the persons who might be exposed; trol during transportation of fibers chapter. and (5) con­ and products. control measures The in consumer industries. Engineering Measures* • Control of airborne asbestos greatly different having a similar technologies from the control aerodynamic size, may be involved. • Enclosure • Exhaust ventilation • Isolation fiber by of engineering methods is not other solid particulate matter though some special problems Engineering control methods and include: 67 DPMC-01572 LAM 008088 Plant design Treatment of asbestos Substitution of alternative materials. Enclosure Unless borne by wind, dust extremely high velocities, inches at fibers, of the most. due to the short particles, travel only This behavior their low mass is travel distance, a good start that the machine may there must be a continual ficient velocity operations, to prevent of asbestos characteristics. toward Because control of asbestos enclosure or hooding. otherwise inflow of the escape of an intake velocity an enclosure is operations is in air—a few true However, must often have openings, to permit manual operation of a machine or so Hence, particularly and aerodynamic dust generated by machine operations enclosures even when impelled at a short distance of 200 adequate. Enclosures involving very large parts carry air out into asbestos its function. the unit at suf­ dust. For many feet per minute at the face of for high-velocity wheels or require special care in design. Exhaust Ventilation Adequate exhaust ventilation, vided for enclosed areas with negative pressure, to remove airborne proper exhaust system is to for asbestos 5,500 operation feet per minute. relatively small concentrations such as of air movement and other carry air at velocities The are used where space material must be carried, shape brake shoes as lower velocities of well-divided in the dust-control systems velocities is at important to 4,500 All parts fibers or asbestos-cement pipe. The higher larger pieces for machines Most systems, that of cut and including low- function well at velocities of feet per minute. of asbestos negative pressure control systems to prevent joints and open seams, faces. Another major should be maintained under leakage of dust as well as to into the plant exceed consideration in a plant's the amount of from loose ensure adequate collection at hood ventilation system is the provision of make-up air—the amount of make-up should slightly must be carried, textile plants. in dust systems ranging from are used where restricted and where pressure penumatic conveying systems, 4.000 a of ventilation-system design. Dusts 3.000 must be pro­ The design of critical and should be accomplished by persons who are experienced in the principles aspects fibers. air exhausted. air introduced A mechanical air 68 DPMC-01573 LAM 008089 suPPly system, and, in most rather cases, than "natural" necessary room ventilation, to achieve the necessary is preferred ventilation per­ formance . Many specifications for duct Industrial Ventilation issued by contruction design may be found in the American Conference of Governmental Industrial Hygienists.1 Even with a ventilation system to good engineering determine ing that principles, the system is to design. Static pressure • Air • Supply, • Fan performance. designed and built according to performing accord­ include: flow capture, Frequent measurements variations is adequately balanced and Such measurement • that periodic measurements must be made and conveying velocities are essential, in the balance and, since plugging and wear can cause hence, efficiency of the system. Isolation "Dirty" operations in the asbestos to minimize human exposure to asbestos particularly vibrating screens engineering measures as thereby In addition other advantages tices not so if he is operations (2) levels frequently isolated asbestos mills, two-fiber such not been able necessitating isolation. there are and to to time-weighted- isolating asbestos-fiber-emitting operations likely them: (1) that present through a plant, an employee working at a dusty opera­ to relax his separated reduce costs below the to reducing fiber levels in restricting access tion is and bagging at are For some operations, ventilation and enclosure have reduce airborne asbestos average limit, industry fibers. adherence to restrictive work prac­ from fellow employees who are working freely at no exposure hazard; for local exhaust also, ventilation, isolation can and (3) make for more efficient housekeeping. Unloading and storage of because of dust shifting or asbestos from bags careless that loading. asbestos is another candidate for are inevitably perforated by Such bags should be rebagged—and vacuum-cleaned within isolation in-transit repaired—or the the boxcar before being 69 DPMC-01574 LAM 008090 transferred required to the warehouse. Also, of course, Bag-opening stations, as well as being enclosed and ventilated, should be isolated from other operations area. The emptied bags up within clean, careful unloading is to minimize bag breakage. in the mixing or should be "isolated" a shredder, enclosed, mately disposed of or a tube that central collection point in sealed containers. conveys compounding by being rolled the opening station's ventilation hood and put sealed bag, isolated, themselves into either a emptied bags from which (In some industries, be mixed with other material and submersed into to an they are ulti­ bags can the manufacturing pro­ cess.) Plant Design Not often is industry afforded constructing a plant measures as As a rule, isolation and dust process But product quality, flict with design for health that place such hazard control at flow efficiency, receive higher priority. efficiency, the opportunity of designing and to specifications the quality forefront control, enlightened management and cost savings can be made only locker rooms, control priority. and cost is aware factors that do not necessarily con­ and safety. An ideal design for isolating a dusty work area is entry of through locker one in which and clothes-change rooms. Two separated by a shower room should be provided—one for street clothes, the other for work clothes and protective equipment. Interposing a shower bath between the two locker rooms makes shower at the end of a shift more likely. (See Figure taking a 3.) The contaminated change room should be under negative pressure, with the exhaust air directed to a suitable collecting system. between the two locker rooms should be connecting doors between change rooms well sealed, it may be possible to use toward Air flow the contaminated room. If and shower are self-closing and the separating shower room as an air lock. Some other important considerations in designing for asbestos fiber control are: • • Engineering a dusty operation so by as as few employees that it can be handled possible. Including a protected observation area next work area so visitors that to an isolated entry of supervisory personnel and can be kept to a minimum. 70 DPMC-01575 LAM 008091 r o O <5 a UJ ^ DO □?a 2 a 5 c is CONTAM ­ INATED ESPIRATOR V,) < < o z a: 5 ° o 3 o -J □ □ NOTHING HOLDING AREA) 1“ O & ■ROTECTIVE □ □ Dia a H Z UJ 5 UJ > cc C3 Q Z Z < a: < D CC -i CC UJ 5 < 3 O o o x cc 5 o X co CC g eS W b . u O O < h < E z a: cc cc a. r o « Ji- ] t 0 D 0 D D D D urn D a: 2 w UJ j o o _i cc o S -J uj o 3 13 □i Jl nnn J 71 DPMC-01576 LAM 008092 • Planning the enclosures, by drafts with layout so and other from fans, indirect, that equipment windows, and doors. right-angle entries and diffuse incoming air • airflow into hoods, exhaust help is not disturbed Off-set doors to deflect currents. Constructing interiors such ledges areas where airborne asbestos do not serve as that beams, pipes, and can settle. Treatment of Asbestos There fiber are various methods emissions. applicable One of to operations manufacture of friction of the most present products, there is rock through or it is Use of has fibers, The and fiber as loose which length of A recent method of fibrous It fibers the yarn.2 Such a coating, face characteristics the fibers is finished require fibers agents are viscous less of products. fibers polymer is not useful where in the to asbestos the inherent sur­ required, particularly when in a matrix with other materials. Treatment of asbestos with These lengths. should present asbestos are to be bound into its long unusable, to reduce airborne are product. pneumatically however, of form, Dust friction products into shorter, the application of that then col­ release at These products pelletized asbestos is material. gravity the manufacture of treatment textile industry the from in pellet a problem in the manufacture of other asbestos-containing asbestos not as States separated can be pumped through little success. but pelletizing breaks shorter is flotation devices. unloaded been tried in such in mining and the United and extruded and dried pelletized asbestos, textiles but with in asbestos for pelletizing and bagging enclosed railroad cars destination, can be used reduce industry. fluff-dried and packaged control is needed only and wetting of filters to Although tolerate moisture, At this mill, a series lected between pillow is wetting. one asbestos mill utilizes wet processing. heavier loose asbestos that will not milling and in the construction At treating effective anti-dusting agents may be helpful. liquids that are applied to dry asbestos by spraying or mixing. The fibers are then dried at room temperature. This procedure retains the performance criteria of untreated asbestos.^ Substitution Although applications, role the use of it in reducing is asbestos likely that is well entrenched in many substitution will play the health hazards from asbestos. For some important future example, one of 72 DPMC-01577 LAM 008093 the largest asbestos that asbestos users, not be used the U.S. in Navy, has construction, issued an overhaul, "Instruction" repair, and mainte­ nance where suitable alternative materials have been designated. Materials asbestos that have been investigated as Fibrous glass to Steel wool Rock wool Kaolin wool Slag wool Exfoliated vermiculite Silica Cellulose Potassium titanate Ceramics Sintered metals Carbon fibers Few alternative materials lack of possible alternatives include: strength, heat of cost. Moreover, that inhaled fibers essential that have proved resistance, as satisfactory as flexibility, asbestos or durability, due to or because since attention has been drawn to the possibility other than asbestos may be carcinogenic,4 it is the toxicity of proposed asbestos substitutes be evalu­ ated. In certain industrial processes where less asbestos toxic materials have been substituted with quality of the product. rubber, plastics, is used as a binder, little effect on the This has been the case in the manufacture of and various adhesives asbestos might be used in paints, and cements. coatings, caulks, Similarly, sealants, less and joint fillers. Satisfactory of asbestos reinforced plastics substitutes have been developed and resins and critical insulating applications, resistance of asbestos for however, in which cannot be duplicated economically. the heat resistance, and insulating properties as and mill board, and thread have ing underlayments, tos fibers of but pipe in paper pro­ and electrical are highly valued—products coverings, fine quality and asbestos-latex flooring felts. found in limited Glass application in roofing and the majority of such electrical these paper products, cloth, floor­ asbes­ are still used. Two of the more successful asbestos and high silica glass fibers, Soda-lime-silica involving glass the use of substitutes, soda-lime-silica are viewed briefly below. Soda-Lime-Silica Glass processes chemical inertness, asbestos roofing felts, insulating papers, felt, For the strength and heat Not many replacements have been found for asbestos ducts for a variety insulating materials. Fibers filaments, platinum dies, made by highly refined are of high quality and 73 DPMC-01578 LAM 008094 uniform size. adaptable Some are Glass at less than one-half micron in diameter and are to highly specialized uses, such as weaving fibers will not burn, but temperatures which vary according to into fabrics. they will soften and coalesce the composition of the Their heat and moisture resistance is limited by applied to them during manufacture improve processing and to the organic breakage during subsequent plying and weaving operations. such a coating, the are impaired to some extent, withstand up temperatures to Exposure of very the effects reduce but High- the fibers will 1,200°F. fine glass relatively rapid deterioration, to to (Without fibers are more brittle and self-abrasive.) temperature properties asbestos glass. film fibers making to water vapor results them less of steam and moisture. Attempts resistant to use in than asbestos them in place of in asbestos-cement products have been unsuccessful because of chemical reaction, between the glass and cement, that decomposes a the fibers. Glass ment, such as Their high fibers are efficient stoves tensile strength, organic fibers, and thermal and refrigerators, greater electrical insulators in types where conditions are not thermal stability resistance make of equip corrosi\ compared with them suitable for elec­ trical insulation. Glass fiber is used in conjunction with asbestos, or as an optical alternative material in Navy shipboard cable.^ A glass-asbestos the supply of asbestos cloth designed during World War textile fibers has on thermal insulation applied with a plied yarn, Glass stronger, but fabrics and As fireproof less fibers fabrics have some they are to and colors is woven and asbestos. lighter and flexure, interwoven glass for asbestos in abrasion, and asbestos for use as theater friction equipment, glass fiber given unsatisfactory results, High-Silica Glass Glass resistant It to extend a covering draperies. poor abrasive characteristics are superior glass glass-asbestos Fabrics made of a substitute in general, each of textile products because are being made in many weights curtains has, or combined they are generally and chemical action. yarns to piping on naval vessels. having one strand advantage over asbestos II continued in use as of chiefly because of the glass. Fibers approximating vitreous to soda-lime-silica glass fibers silica in composition in resistance to the 74 DPMC-01579 LAM 008095 A action of water vapor and high facture, however, melting point temperature. because fused silica is They are difficult extremely viscous at to manu­ its. (1,725°F). Administrative Measures Administrative measures the hazard (a) of in limiting exposure the number for any the workplace, Limiting are a complement the workplace. and of employees given person, (d) the Number of of asbestos may be • and • involve limiting include the duration restricting smoking and eating Employees exposed to in Exposed to excessive airborne concentra­ contaminated areas engineering "Plant Design" Reducing (c) (b) limited by: Restricting access also exposed, smoking cessation programs.* The number of employees tions to engineering control of Possible administrative measures design; further on in to a minimum hence, this the number of (this also measure can see "Isolation" chapter) persons handling asbestos • Conducting where particularly the number of Smaller numbers and effectively that is only of and and occasionally the Duration of As previously, the plant exposed controlled, Limiting noted in continuously trained, casually dusty operations persons Exposure at a minimum. employees protected are more easily than a larger group exposed. for Any the OSHA standard time-weighted average of no more during shifts is than 2 Given Person for asbestos fibers, greater is an 8-hour than 5 Another administrative measure, which has been used in the British dye­ stuffs industry in connection with cancer control,^ would be to give preference to job applicants who are of previously been occupationally exposed is that ployees' the lifetimes will be somewhat reduced. The reasoning here in theory with regard However, to lung the em­ while this meas­ cancer, it does take into account other asbestos-related diseases or even the pos­ sible aggravation of adverse health conditions to be asbestos-related. considerations Moreover, that would need smoke (because of to the same not normally considered there are other ethical and economic to be explored. administrative measure—giving preference ject age and who have not risk of developing asbestos-related cancer during ure may have some basis not an advanced to asbestos. the greater risk to job Still another possible applicants who do not to smokers)—would appear to be sub­ considerations. 75 DPMC-01580 LAM 008096 / micrometers 10 fibers per milliliter. shift, employees may be exposed fibers per milliliter so equivalent reductions exposure exceed As 10 an example: equivalent are subject employees asbestos Or, of Control of for example, exposures, and sufficient work force is that economics Restrictions For any only is assumed (2) the for 4 hours as long as they the day. the first half for 1 hour, The employees of exposed the 8- to an air­ as long as he fiber per milliliter deficient that: (1) in a number of exposure the worker receives levels will no asbestos than those associated with his work; greater than 5 microns there available is in length is counted are Other assumptions are for required alternation of (increased payroll) is that zero physiological present but not standpoint. not a that a person­ factor. on Smoking and Eating a strong eating, should be restricted corporate stand should be estab­ drinking, or smoking on to a designated, and frankly a change in policy, explained as the job. clean location after established decontamination procedures If such action represents should be clearly for by can the shift. other the practice of These activities followed. it toxic materials, lished against 8 hours, than 1 the submicron fibers unimportant form a toxicity and for during for practical purposes, (4) instance the remainder of a worker could be of fluctuate; per milliliter level at which, response; hours on or off shift, 2 fibers in no can be exposed fibers per milliliter in effect, not above 2 compensated the shift would be covered by zero exposure 7 levels are fibers per milliliter, which exposure using averaging is since, remain constant, visited for exposed to a level of no more respects that on a shift level of 4 zero exposure for the remaining nel, except to a 2-fiber exposure to borne level of 9 (3) excursions per milliliter. remaining four hours was such in exposure, who had received hour day. This means that during any single to airborne asbestos long as fibers to an airborne is also concentrations must in length per milliliter of air; never exceed a step being have been the change taken to pro­ vide a safe work environment. It is noted in a recent publication that asbestos 5 pm having a length-to-diameter ratio greater than contrast light microscopy) account fibers present in industrial greater count of than 5 fibers 3 for approximately settings and pm in length corresponds that, roughly than 2X_ of all asbestos hence, to longer (using 430x phase- every fiber an actual fiber 50.7 76 '.*n. DPMC-01581 LAM 008097 I Smoking Cessation Programs Because of asbestos the interaction of in producing lung in its own right, cancer control measure. that have been cessation, tobacco smoking cancer, a smoking and working around and since smoking is a health hazard cessation program might be undertaken as Unfortunately, however, the various tried have rarely brought about significant although smoking rates have been reduced. It a programs long-term is possible that recent moves of federal and state governments to restrict smoking in public places* and public-service media campaigns to educate the pub­ lic on the hazards of smoking could improve the efficacy of cessation programs. Various of approaches to smoking this monograph with a view available options. If should be undertaken, care worker it is cessation are discussed to providing a broad decided in Appendix E perspective of the that a smoking cessation program the discussion should be of help to the health­ in selecting an appropriate program. Work Practices, Including Housekeeping and Use of Personal Protective Equipment Changes of in work practices often may be reducing occupational exposure the most to asbestos. cost-effective way Some of the ways in which work practices may be modified include: • Mixing asbestos mortar in closed polyethylene bags rather than in mortar boxes or buckets. • Maintaining central fabrication shops material the on-site is sent Permitting power • Using • field for tools to be used only single-point cutting and or from which insulation installation with minimal cutting or sawing. • saws to in central shops. chipping tools, rather than cutting equipment using abrasion. Jettisoning polyethylene bags into the product mix when possible. • Substituting vacuuming for equipment with compressed • Good housekeeping • Use of personal protective equipment Since 1976, that the blowing off 19 (as discussed facilities, and in more detail below). states have passed a total of restrict smoking in public places health of machines air. of (also discussed below). 23 antismoking ordinances recreation, waiting rooms of and restaurants. 77 DPMC-01582 LAM 008098 Housekeeping Good housekeeping asbestos. is essential Waste materials such debris should be picked up shift, these bags tained therein, activity, it, should be levels scrap, of taped shut, airborne shavings, in plastic bags. labeled as At to or other the end of a the hazard ledges, equipment, overheads, con­ and other can become airborne when disturbed by drafts because the removed. fine deposited on remote ledges, Sweeping fibers pipes, the dust around. is not are entrained and Nor is wet mopping a satisfactory way to spread reducing and disposed of. and it should be however, to rejects, and placed Asbestos dust on floors, plant surfaces as or work the way into to remove the air and other inaccessible surfaces. of cleaning, Vacuum cleaning is since it tends only the recommended method— preferably a central vacuum system. Personal Protective Equipment The control measures previously nificantly reduce exposure first. If, however, pected event creates permitted, ate, discussed in this to asbestos these measures a potential fibers, and chapter are not sufficient, for exposure greater or if an unex­ than the maximum personal protective equipment will be necessary. respirators and protective they should never serve as can sig­ they must be employed To reiter­ clothing must always be available, a replacement but for engineering control mea­ sures . Respirators Respirators may always be necessary during the cleaning or repair of exhaust ductwork or during manual shakedown of in baghouses. Also, this form of protection may be method of controlling asbestos insulation or exposures during the application of The use of respirators Since he is assigned to do. mination include: the is not task, present the to be taken lightly, respiration of hair, Factors that must be considered is and glasses; type of that in such a deter­ physiologic/physical ones such as oxygen needs beards, toward wearing The however. to whether an and perform whatever work it medical conditions such as pulmonary or cardiovascular disease; disposition thermal the wearer—and, are a nuisance—a determination must be made as individual can use the equipment feasible the removal of some asbestos products. the devices place a burden on at best, collection bags the only for that may be and psychological a respirator. respirator needed—for example, man-powered—will be dictated by the preceding factors powered versus as well as by the 78 DPMC-01583 LAM 008099 Jl concentration of airborne asbestos fiber.® should always be rechecked whenever process, control, worksite, fitting, maintenance, concentration of fiber there are significant changes or climate.) and cleaning (The Respirators in require proper to be effective. The elements of an acceptable respirator program are set by the American National Standards Z88.2-1969 "American National Institute Standards (New York) Practices in ANSI forth Standard for Respiratory Protection." Protective Clothing Special clothing, not to be worn outside be worn by all asbestos workers—not only to the workplace, protect them, but should to curtail exposure of other persons. The most satisfactory basic protection is afforded by coveralls, preferably made of cotton-polyester material—cotton alone cannot be used, because tenaciously. tively static build-up inexpensive and laundry workers, cal action, piece, sures they eliminate or sparks. Moreover, without pockets, some clothes. cuffs, for necessary openings. or is in the hair, should be worn under Street clothes in a and, in the room, a filtered to heat should be one- clean each day and and lightweight paper where do not prevent the accu­ the hats are required, a paper Either form is rubber galoshes, satisfactory as long from the plant. and personal effects and work clothes "contaminated locker" and room. clinging asbestos exhaust chemi­ are hard- and with adequate clo­ should be Hard hats system. should be kept protective equipment (See Figure VII-1.) leave a restricted work area they should room and remove they can lead coverall garment form of canvas booties, are also needed. they are not worn away kept for exposure of them. coverings, or safety shoes, and also required, mulation of conditions" the cloth of paper suits rolled edges, Coveralls are satisfactory. as to they are compara­ from the plant. A head covering fibers types The surgical-type caps Foot to adhere although the potential almost airtight, if worn over street must never be worn away cap fibers coveralls, are easily torn or perforated by body movement, finished and nonporous, stress causes Disposable paper enter in a "clean should be When personnel the "contaminated locker" fibers by using a vacuum equipped with Protective equipment should be removed 79 DPMC-01584 LAM 008100 (respirators last) The worker should and deposited the "clean conditions" If in rather in writing of "contaminated on his locker" personal outer room lockerj clothing in room. laundering of work clothing service, than in the plant, is and clearly marked done by an outside the the asbestos hazard. clothing should be vacuum-cleaned, sealed, the then shower and put laundering laundry service should be advised When collected for laundering, dampened, "Asbestos packed the in plastic bags, Contaminated Clothing—Wet Before Handling." Control in Specific Manufacturing and Consuming Following are some observations specifically tries to several major and to demolition and rip-out. exposure outside of mining, tries difficult—persons at is proper work practices, on exposure control as asbestos asbestos and, Industries manufacturing Generally it relates and using speaking, indus­ control of milling and manufacturing risk are moreover, less aware of indus­ the hazard and of engineering controls and personal protective equipment may be lacking. Asbestos Textile Production Control of asbestos has exposure during production of presented a greater problem asbestos products. In part, that was originally designed than during asbestos textiles the manufacture of other this may be due to the use of machiner for processing other, less toxic, fibrous materials. Fiber preparation—which involves fluffing, combing and which generates heavy concentrations by the mixing of Dust grading, beating, of dust—is asbestos with another material such as and followed cotton or rayon. from these operations must be controlled by enclosures and venti­ lation. Carding, twisting,' spinning, dry proc >ses which, weaving, and braiding by their physical arrangement, to enclose and ventilate, and it appears that current eliminate excessive exposure from these operations. ture and humidity and exposures. It is and since fibers to keep technology air change cannot tempera­ to reduce the ventilated room at a to help maintain proper the rate of are difficult Control of general room ventilation have been used usual practice slightly positive pressure humidity, of are very is temperature and often as frequent as 80 k. LAM 008101 one complete change every 6 minutes, it is necessary to recycle the air before cleaning. Asbestos Paper Since much of little dust wet sheet is the paper-making created. Drying process which gradually high-exhaust-volume hoods the water vapor and to transport serve to remove any asbestos it dust involves wet materials, usually accomplished by passing over steamheated rollers, The low-pressure, ing is away that from remove are used the the moisture. to collect the drying paper also that may be released during the dry­ operation. Bulk packaging of paper products or beams is a dry operation, but are effective dust-control measures In general, by winding local exhausts for this them on spools, operation. the use of hydropulpers with pulpable bags; ventilation rates; and the serve to maintain asbestos reels, and vented area hoods proper control measures mentioned previously will exposure in paper making at acceptable levels. Asbestos-Cement Pipe and Sheet The prime point for application of manufacture of asbestos-cement into which dry asbestos agitated and at machined, cement the buffed, is introduced and exposure in which the the asbestos interim stages.) enclosures in the the mixing vat (The addition of water, in ventilation with carefully designed dust control at are at final stage where the finished product and packaged. curtails dust control procedures pipe and sheet is is cut, sand, and Local exhaust are essential for proper the critical exposure points. Automotive Brake and Clutch Repair The greatest brakes exposure to asbestos during and clutches occurs when brake drums with compressed air and when brake Brake drums beveling should be vacuumed operations will have linings instead repair of automotive are cleaned by blowing them are ground and beveled. of blown out. Grinding and to be controlled by enclosure and exhaust ventilation. Construction Control of difficult since exposure to asbestos few operators fibers in building are sufficiently localized construction is to permit the 81 DPMC-01586 LAM 008102 use of enclosures or exhaust ventilation. coupled with respiratory protection are excessive exposure to fibers sawing or shaping of asbestos application of Generally, products the application of A vacuum device ate dust and in the installed on such taping, spackling, does not require extraordinary are securely embedded tape, fibers into as or spackling or floor preventing from compounds; roofing, low and and siding since asbestos little or no dust the periphery of on-site mixing and tile. procedures, product and the air insulation; floor tile, control fibers would help maintain recharging of of that may occur during necessary asbestos patching, sanding and finishing of General room ventilation the only means is a sanding wheel to levels of fibers created. evacu­ exposure and the work area can be controlled by careful housekeeping. Much of the exposure substitituions in the building on using alternative materials hazard of industry has been reduced by for asbestos-containing materials, asbestos fibers is anticipated as and further emphasis awareness Demolition and Rip-out of Asbestos-Containing The potential for exposure ships and buildings is high. and less already years in recent years but, to asbestos rip-out of that Insulation fibers during demolition of asbestos thermal insulation there is less so much asbestos material control during demolition and rip-out these operations will remain potentially hazardous for The following measures will help Airborne dust the health contain asbestos have been used because in place and because dust to come. • and during Insulating materials is difficult, of increases. can be reduced to reduce the hazard: considerably by soaking the insulation—nonabsorbent surfaces punctured to permit water to be introduced, • surfaces soaked by a fine, the impingement of the water upon the surface. Insulation should be rather than by Materials Slurries that dust does not arise removed, if possible, fitted with dust from by sawing or collecting devices tearing away. removed should not be allowed ground but • absorbent spray so cutting with tools • and low-pressure water to should instead be placed in bags of waste that fall must not be fall to the for disposal. allowed to dry— they should be removed while still wet. • If possible, employed at • a high-capacity exhaust system should be the work site. Where wetting and exhaust ventilation are not possible, control efforts hazardous should be directed toward isolating the operations. 82 DPMC-01587 LAM 008103 1 Control of Emissions to the General Environment Air Pollution Control Methods similar to for controlling variations due ations asbestos those for controlling to the special characteristics that generate asbestos tive pressure, emissions to community air are any particulate matter, fibers careful cleaning of the air in the ventilating However, air-cleaning methods mentioned below may be adequate rip-out. they are not practical for use Control of general air use of water Since oper­ are usually conducted under nega­ will adequately control general air pollution. related activities, with some of asbestos. pollution in this system while the for many asbestos- in demolition or case is limited to sprays. The most useful control method is fabric filtration, and design parameters for successful systems have been published.9-12 The effi­ ciency of fabric filter units from 95% to 99.9% removing the filters operation, Wet range on requiring used to collect asbestos the basis of weight. and packaging collectors—wet dynamic scrubbers and Venturi-type collectors— to 90%. The fibers collected are fibers disposed of Mechanical collectors efficiency range as wet the size, are dry, design, many of and (cyclones) scrubbers, energy when they are removed out other from power other Usually, in a the slurry is in a suitable container. generally operate with the same the actual efficiency depending on expended. them are fractured, Because the fibers are dry, require no and them for disposal can be a dusty slurry and may pose a water pollution problem. the wet operate dry, the use of personal protective equipment. in efficiency from 50% filtered and fibers ranges These units Although the fibers thereby limiting their collected further use. personal protective equipment may be required the collectors than for disposal. to move air and than the collector Because they they have no parts to wear shell,2 mechanical collectors are econom­ ical to operate and maintain. Electrostatic precipitation has proved other air-pollution-control means the best, 70% for to be less asbestos effective than fibers—yielding, at efficiency. Water Pollution Control Until waters recently, little attention was no published information on such waters. large, and more: a significant amount is directed associated with asbestos manufacturing, the volumes recirculated, many plants most and toward the waste there is virtually The number of plants of wastes have been relatively small. of process water plants have some are situated where they is not Further­ in manufacturing operations form of waste can discharge treatment, and the process waste 83 DPMC-01588 LAM 008104 waters to municipal sewers. asbestos fibers processes Recently, in the air has into wet ones and mining and from piles of however, resulted (2) in (1) increased use of water sprays tailings or gob concern over conversion of some dry to control dust (low-grade ore), from thereby increasing the potential for water pollution. Waste Water Treatment Processes The standard processes water have been • found for removing suspended-solid wastes from to be satisfactory Pretreatment—removal of aggregates • Primary • of for removing asbestos oil, grease, and the • larger solid matter. treatment—sedimentation and chlorination Secondary treatment—biological processes aerated fibers: such as lagoons Tertiary treatment 13 Tertiary treatment—sometimes referred to as "advanced waste water treatment" or "physical-chemical treatment"—is required if the effluent from secondary treatment is not considered satisfactory.^ The several means treatment of removing suspended solids including microstraining, chemical clarification, and In microstraining, diatomaceous deep-bed, earth granular media filtration. the waste water is strained mesh screen on the surface of a rotary drum that zontal axis. water and As the drum rotates, to a position Diatomaceous tion that utilizes is built up The fibers from which earth the solids filtration is a on a a are in with the on its hori­ strained out of the from the drum. form of mechanical separa­ finely powdered supporting medium, removed are mixed through a woven revolves they are removed diatomaceous earch, (coated) in tertiary filtration, to trap filter-aid that solid material. filter medium, and both must be disposed of. In aluminum, the chemical clarification process, iron, or calcium oxides fine solids. Coagulation particulates are aggregated process if previously While followed by is followed by a into larger sedimentation, formed are allowed some of are added to chemicals the water dumps to that will floes the bottom of the solid material will have been the material remaining must be removed by such as coagulate flocculation phase, in which the to settle to in which settle. This that have been a settling tank. removed by sedimentation, filtration, usually carried 84 LAM 008105 out in beds of a porous medium such as media such as sand and coal, or Control of Asbestos The extent Fibers of asbestos been established conclusively, extent ingested sand, in and sand or coal, coal, and in Potable Water the nation's water supplies has not asbestos might be harmful One method of reducing asbestos involves minor modification of standard that in most water-treatment the number of asbestos below-detectable limits fibers (<20,000 tion systems have been shown useful as tion.^ a low-cost to humans. of filters. used in the majority of as well.16 During 1974, is fiber 0.06 FTU source. per in potable water techniques consistently reduced liter). in areas show to Even simple filtra­ of high could prove fiber concentra­ indicate that both alum and polyelec­ removal and filtration plants that they can be since sand in North America, two diatomite-filter pilot The asbestos Preliminary results a definite advantage, gallons per minute removed over drinking water plants. fibers one study This intake of concentrations to what the meantime, to be partially effective and trolyte coagulation optimize with sand In coagulation/filtration could be interim measure The results Supplies it has not been established it is the opinion of some researchers that oral should be reduced as much as possible.^ as practiced or a combination of garnet. plants turbidity of the fiber finished water was with over 95% of are and Europe operating at 80% of amphibole asbestos (Formazin Turbidity Units), used filters the 10 from a 0.05 or fiber removed. Removal of amphibole fiber seemed to be significantly better than that of chrysotile fiber.^ The pilot plant study suggests the following conclusions applicable to the filtration of Lake Superior Water at Duluth: • Several to 98% filter operating conditions removal of viding the best can result asbestiform fibers. filtered water would involve of either alum-coated Hyflow Super Cel grade) • as body feed and precoat, filter aid (or continuous coagulant the influent water. filter equivalent The operating data filters grade) as precoat plus B polymer filtered water and very difficult to a to that vacuum diatomite are significantly more expensive as of producing the use (or equivalent or alum-coated C-512 feed of Cat-Floe indicate in 95% Conditions pro­ operate under that a means they would be conditions of high turbidity. 85 DPMC-01590 LAM 008106 • A least-cost-design analysis plants suggests life and for a ceeded only gallons gal. turbidity of 5% of of water It is the tection against price for a in if water turbidity of about 30,000,000 a cost of 5.56q per the study increases occur 20-year 1.9 FTU equalled or ex­ time could produce per day at suggested the of several alternative that a plant designed that for 1000 the best pro­ filter-aid would filtration plant were designed for a 2.5-3.5 FTU. Waste Disposal The greatest hazard associated with asbestos potential improper for air emissions final disposal. At waste material—whether posed of, reused, may arise. Hence, each step the waste is or otherwise in the handling of to be concentrated, treated—hazards to products and reducing the the from the solid isolated, dis­ treated with the their production. The most desirable general waste management priority, are;18 Waste reduction—by is the waste handlers asbestos-containing wastes must be same respect accorded asbestos • solid waste arising from improper handling and options, amount of substituting less-hazardous material, in order of asbestos used, and making the process more efficient. • Waste separation and concentration—segregating hazardous and nonhazardous wastes. • Waste recovery—reusing • Secure ultimate disposal—disposal that precludes The most discussed in aration, (c) important future of that secure transport, to landfill in a way reentrainment. aspects the paragraphs the material. controlling asbestos follow: and (d) (a) solid waste are identification, (b) sep­ secure ultimate disposal. Identification Obviously, solid waste there can be no if asbestos has waste stream issuing not been control measures directed at asbestos identified as part of from a plant—identification and asbestos-containing materials then the solid tracking as necessary. 86 LAIW 008107 Separation* The that waste prevent source of asbestos-containing waste having been should be separated exposures to workers during separation. tities of dry asbestos wastes, are heavy-gauge, of as a slurry, from nonhazardous wastes, impervious provided the most containers Asbestos may also be slurry does not to For holding small quan­ generally satisfactory plastic bags. the identified, taking care disposed dry between collection and disposal. Secure Transport Waste must be transported to out producing emissions. In practice, or private) aware of disposal services this means cannot be that community relied upon unless the hazard and of proper handling procedures, can provide closed is the ultimate disposal site with­ disposed of will likely be must be The on to and unless the ultimate disposal site. the premises of a plant, employees of the they If waste facility familiar with handling precautions. integrity of taken not containers conveyance (public they are to rip such as cans the waste or container must be maintained. tear plastic bags, or bins must have Care and more-permanent waste tight-fitting lids that will not come off during transit. Secure Ultimate Disposal The only disposal of asbestos waste "secure ultimate disposal" with a 15 layer that is covered that is at and maintained, cover. a resinous (2) or Emissions 60 it can be considered of nonasbestos-containing waste or earth if depositing that in a site centimeters deep is an adequate vegetative cover centimeters deep if from waste may also be there is no such vegetative controlled by (1) or petroleum-based dust-suppression cover at by wetting the waste with water and sealing least is also established it maintaining the site, in an or impermeable container before disposal. Covering waste with soil and planting vegetation does not require as much care as dust-suppression in most agents; is needed hence, for maintaining a disposal site with it is the more desirable control method cases. Control During Transportation The not transportation of a significant asbestos ore from mine source of airborne asbestos to mill fibers, is generally although private A See Chapter IV, Occupational Exposure, for additional details and applications. 87 DPMC-01592 LAM 008108 mine-mill roads may be paved with liberated when by tarring, chemicals. trucks pass by. sprinkling, or tailings Some of treating EPA regulations permit the from which these fibers can be emissions can be reduced roads with dust-suppressing no visible emissions from mine or mill roadbeds. Manufactured asbestos products not firmly embedded in a matrix,* such as asbestos textiles or spray asbestos materials, should be either: • Transported and stored in enclosed, impermeable, sealed areas • Wetted and covered with tarpaulin or similar material to prevent drying • Appropriately packaged—packaging durable enough normal handling, and that warn persons Areas used to is that bears about leakproof easily visible labels the same time to not appropriately transport Before the areas ulations of asbestos are used to thoroughly, with a vacuum cleaner having a high-efficiency Personnel working in or near areas regulated asbestos that is the protective procedures used not appropriately outlined the asbestos transport or store goods, fiber should be removed earlier in pack­ or store other Such areas should be posted with signs warning of hazard. and the hazard. transport or store asbestos aged should not be used at goods. that to withstand abrasion or puncture during accum­ preferably filter. to transport or store packaged should this chapter. firmly embedded follow I Manufactured products asbestos cement, expected to containing asbestos asphalt, result plastics, in asbestos air and in a matrix— the like—may not reasonably be concentrations that are high enough to warrant packaging. 88 I V DPMC-01593 lam 008109 ! Chapter VII CONTROL OF THE ASBESTOS HAZARD- MEDICAL MANAGEMENT A means of limiting, can be somehow related ment in to the industrial population, asbestos to be hired exposed other attributes for jobs to involving asbestos In this way, they possess asbestos these diseases, tos exposure can be detected early to these diseases by recommend exposure. and conditions likely enough so intervention may successfully less, asbestosis may progress sure, and screening programs lung cancer have not yet that they not Those workers necessarily even after for proved disorders predispos­ to be aggravated by asbes­ that limit removal their from exposure course. Neverthe­ removal from asbestos the early detection and to be more expo­ treatment of than marginally beneficial. the Workforce The extent persons risk for and asbestos-related diseases, to Composition of that should be enrolled in a medical monitoring program. hopefully, ing or medical diseases recognize during a preemploy­ examination persons who have increased virtue of any is for jobs to which discovering involving asbestos and not hiring particular situation will be limited, political considerations. Each own program for dealing with certain high-risk exposure can be put inevitably, into effect in by social and industrial physician must develop his these matters in relation to preemployment examination policy. The desired net effect of the employment screening approach assemble and maintain a workforce whose combined average oping disease, were it to tional asbestos expected with exposure to asbestos, include persons whose exposure, is are relatively higher. to be most effective in relation to evidence of less a causal role of than what individual risks, asbestos greatest—lung cancer, tosis. Summarized below are some considerations it would be The approach would-be is most convincing and the problem is to even without occupa­ those diseases tude of is risk of devel­ mesothelioma, for which the magni­ and asbes­ for applying control 89 DPMC-01594 LAM 008110 over the certain industrially individuals exposed population by excluding from employment on medical grounds. Lung Cancer Lung cancer exposure and is today related disease. the most exacts Several frequent of cancers related the heaviest mortality of risk factors for lung any to asbestos asbestos- cancer have been identified: • Cigarette smoking cancer, tant • and, greatly the mortality from lung it is the most impor­ single risk factor. A history of siblings, offspring—has been lung cancer magnitude of risk of cigarette smoking, • increases based on present knowledge, in a first-degree relative—parents, lung and, cancer to products; creosote; Nonmalignant confer almost both factors to are coal tar, mustard gas; affecting the respiratory disease may radium; increase lung lung include arsenic; petroleum, nickel; as synergistic enhance the risk of Such carcinogens chromium; the same the general population carcinogens expected in an asbestos worker. chloromethyl ethers; for together, Prior occupational exposure also may reasonably be shown to cancer and by- and uranium. the risk of lung cancer. Pulmonary fibrosis has been noted in association with lung cancer in persons with scleroderma^*^ and certain rare hereditary diseases of the lung such as fibrocystic pulmonary dysplasia5>6 and congenital cystic disease of the lung.'7 Several reports have associated an excess chronic bronchitis, smoking habits.®-^ risk of lung cancer with after taking into account differences in However, such studies have often employed broad smoking categories and have neglected such important vari­ ables as duration of smoking and extent of inhalation.^ Perhaps most convincing was attributed blood relatives case the finding of a substantial excess mortality to nonmalignant respiratory diseases of lung cancer spouses.And cases among nonsmoking that was not present significantly higher rates of among impaired forced expiration have recently been found among never-smoking relatives of patients with lung cancer or chronic obstructive pulmonary disease when compared with neighborhood controls.^ Experiments with animals indicate that individuals with asbes- tosis may be at increased risk of lung cancer, level and duration of asbestos exposure.^ Possible levels cells of laboratory measures of lung-cancer risk include aryl hydrocarbon hydroxylase and the in sputum. regardless of Aryl hydrocarbon hydroxylase condition of (AHH) is inducible exfoliated an inducible 90 DPMC-01595 LAIM 008111 enzyme such thought as to be are found investigators has human tissues in responsible reported appear for tobacco smoke that converting hydrocarbon carcinogens to an active form. levels of to be genetically One team of inducible AHH activity regulated and in that patients with bronchogenic carcinoma have higher levels of inducible activity than controls.,17 Inducible enzyme levels, therefore, might indicate among cigarette smokers ing lung cancer. those At present, individuals however, at greatest risk of develop­ there are numerous difficulties with the assay technique even in the most experienced laboratories, and the method is not ready for general use.l® Furthermore, the associa­ tion between levels of inducible AHH activity and cancer has not yet been firmly established.^ Examination of exfoliated cells assess the state of observed ring the human to develop after a series over several years. found in sputum has been used tracheobronchial of tree. Cancer has gradual cytological changes These changes have been categorized to been occur­ into stages of regular squamous cell metaplasia, various degrees of a typical squamous cell metaplasia, carcinoma in situ, and invasive carcinoma.20 The more severe the cellular changes, the greater is the likelihood of developing lung cancer.21 Cytological examination of sputum can be used to complement time, the use of the condition of effects tation of all operating to risk factors exfoliated risk factors, the widespread use of of laboratories samples.22 capable of Persons with any of this age, the at any one interrelated and latency. A great technique at present is limi­ the paucity accurate cytologic interpretation of sputum the risk factors sputum examination reveals cytopathology than moderate atypical squamous for jobs listed above since, cells must reflect involving asbestos for lung cancer or whose of severity equal to or greater cell metaplasia would best not be hired exposure.* Mesothelioma Little is known about susceptibility to mesothelioma, cause of mortality The evidence in asbestos workers. that asbestos highly suggestive, mesothelioma. with other ficial. It is but not as Therefore, risk factors causally related to overwhelming as it identified this for for lung that except individuals less bene­ for family history, cancer generally apply of the larynx. Risk of laryngeal cancer has, in addition, lated with alcohol consumption.225 This cancer is rare, to cancer been corre­ and most susceptible persons will have been screened from employment to exclude persons with elevated risk of is lung cancer and disease would probably be however, important laryngeal cancer is the exclusion from employment of for should be noted, the risk factors an Persons who have had an in efforts lung cancer. 91 DPMC-01596 LAM 008112 asbestos-related pleural effusion may be at great risk, asbestos and further exposure should be prevented. Asbestosis Exclusion from employment of those persons most susceptible to disease would likely prove more efficient exposure to asbestos is a necessary mesothelioma, for which of cigarette smoking,27 antigens,30 and questioning for asbestosis to date no method have not been established,31 for identifying from medical those individuals who are more susceptible Because of disability the potential adverse effects from asbestosis piratory disease, of testing or to asbestosis. further respiratory in individuals with existing chronic it would be prudent not involving asbestos for which than for lung cancer or it is not. However, despite suggested effects immunological response,28,29 and specific HL-A risk factors there is for asbestosis, factor, to hire such persons res­ for jobs exposure. Early Detection and Treatment of Asbestos-Related Diseases In general, detected early, oftentimes efforts. treatment is far of asbestos-related diseases, from satisfactory. death or severe disability Furthermore, programs supervenes even when rarely possible, despite for early detection and the risk of instilling a false sense of from more primary efforts Cure is and the best of treatment run security, which may detract to prevent disease by controlling exposures. This must be kept in mind during the subsequent discussion. A suggested protocol for preemployment and follow-up medical examinations tos workers is given in Table of asbes­ 7. Lung Cancer Screening programs, which rely on roetgenograms and symptom ques­ tionnaires at improving intervals of the changes of six months have been notably unsuccessful survival from lung cancer.32, delphia Pulmonary Neoplasm Research Project reported a rate of months only 12% of individuals whose of a negative roentgenogram, were detected more than 6 months as 33 5-year survival tumors were detected within 6 against 4% in those whose tumors afterward. A semiannual screening program conducted among residents Veterans Administration domiciliaries films, questionnaires, and operative survival of only in The Phila­ and consisting of of stereoroentgen sputum cytology slides reported a 3-year post­ 12%.21 This study documented a considerable 92 LAM 008113 Table 7 MEDICAL EXAMINATIONS FOR ASBESTOS-EXPOSED WORKERS Preemployment Questionnaire: medical history, family'history, history of smoking* and consumption of alcoholic beverages, occupational history Physical Examination: concentrating on the oral cavity, chest, and abdomen and Including a digital examination of the rectum Spirometry: including measurements of vital capacity, forced vital capacity, and forced expiratory volume at one second Chest X-ray: posteroanterior and lateral views (14 x 17 inches) Sputum Cytology Follow Up Nonsmokers, Ex-Smokers, and Smokers Who do not Inhale • No More Than Mild Atypical Sputum Cytopathology: ometry, chest X-ray, and sputum cytology a yearly questionnaire, spir­ • More Than Mild Atypical Sputum Cytopathology: a yearly questionnaire and spir­ ometry; chest X-ray and sputum cytology every 4 months • 40 Years Old and Older, At Least 20 Years from Onset of Asbestos Exposure: add fecal occult-blood testing and an examination of the oral cavity every 6 months Smokers Who Inhale • Less than 15 years from Onset of Asbestos Exposure: -No more than mild atypical sputum cytopathology—a yearly questionnaire, spir­ ometry, chest X-ray, and sputum cytology -More thqn mild atypical sputum cytopathology—a yearly questionnaire and spir­ ometry, chest X-ray and sputum cytology every 4 months • 15-20 Years from Onset of Asbestos Exposure: -No more than mild atypical sputum cytopathology—a yearly questionnaire and spirometry; chest X-ray and sputum cytology every 6 months -More than mild atypical sputum cytopathology—a yearly questionnaire and spir­ ometry; chest X-ray and sputum cytology every 4 months • More Than 20 Years from Onset of Asbestos Exposure: -Less than 40 years old—a yearly questionnaire and spirometry; chest X-ray and sputum cytology every 4 months -40 years old and older—add fecal occult-blood testing and an examination of the oral cavity every 6 months. Since smoking is such an important risk factor, breath should be sniffed for tobacco odor; and in situations where the reliability of smoking histories is in doubt, levels of expired air carbon monoxide or serum thiocyanate may be used to distinguish cigarette smokers from nonsmokers. Sources: Protocol modified from the Mt. Sinai School of Medicine, Environmental Sciences Laboratory Pulmonary Surveillance Program for Asbestos Exposed Workers. 93 DPMC-01598 LAM 008114 amount of inter- and intra-observer variability in the of sputum smears and chest X-ray films, but noted positive and suspect sputum cytopathology the screening method by its specificity.21,34,35 Currently, Johns Kettering Cancer Center months. At physicians (PA) each at and frankly cancerous isotope studies are undertaken, tion rule out to localization is cells or if consists tumors, which are likely and had a better cancers detected after an Whatever • to radio­ tract. If investigation succeeded if necessary by that no more cancer may be expected more observation is of survival. were detectable by the result of lung to sur­ needed in order Roentgenographically occult postoperative prognosis. (64%) and endoscopic to be centrally placed, cancers grams, of However, to determine actual rates from procedures from the Mayo Lung Project suggest or more. to if a single sputum specirepeated specimens the upper respiratory a meticulous third of detected cases vive five years opposed and a thorough otolaryngologic examina­ cancer of not achieved, Initial results of posteras Detailed radiologic follows utilizing fiberoptic bronchoscopy, bronchographic studies.26 than a three films.36>37 tumor are set into motion. is made four for patients having the same individual contain markedly atypical cells, localize a every reviewed by 350-kV PA views, In the presence of normal chest X-rays, ment contains administered chest X-ray is the Mayo Clinic itself conventional PA and lateral are under way at and Memorial Sloan- and check roentgenography stereoroentgenograms compromising the efficacy of sputum cytologic and questionnaires the Mayo Lung Project follow-up examinations oanterior University, to evaluate individually; the addition of the sensitivity of follow-up programs Hopkins chest X-rays, increased 50% without significantly large detection and the Mayo Foundation, examinations, about interpretation that were generally smaller Most newly diagnosed chest X-ray alone, and only initially negative screen were lung 13% of first noted as symptoms.26,37 clinical the outcome of the current detection and follow-up pro­ certain limitations will apply: Some individuals of inability to should be to undergo operation if such persons ultimately ticipants not contribute in a necessary.38-40 to lowering of is, a screening participant was to be operated on, failure of To screen but also might the morale of the screening program—that the death as it becomes not only would be wasteful, or unwillingness others ineligible for screening because tolerate pulmonary resection or unwillingness other par­ whether or due to inability it might be regarded by the program. 94 J DPMC-01599 LAM 008115 • A considerable number in of persons may discontinue participation the screening program because employment, or other reasgijis. of retirement, Since the termination of incidence of lung cancer increases with age and has been found in one study to be higher among screening dropouts,38 there is reason to believe that persons who gram may in discontinue fact be at participation greater in a screening pro­ risk. • A certain proportion of screening examinations will be found be incomplete or technically unsatisfactory.^ • Once a cancer has been detected, there will until localization and operative resection. delay, the screening • less the potential benefit centers to The greater can accrue extrapolate from results of medical care industry program. able of inevitably be a delay this from the program. It will be difficult premier that to to likely obtained at results (The difficulty in finding in an average laboratories cap­ accurate sputum cytologic diagnosis has already been mentioned.) • The considerable financial expense of a screening program and the drain on available time of medical care personnel should not be overlooked. • Despite screening, some cancers will not be detected early; despite early detection, and certain cancers will be inoperable or have a poor prognosis. • A not-inconsiderable percentage of persons who will have been successfully operated on to remove a lung cancer will a second tumor.36 Despite means of these limitations, asbestos-related diseases sputum cytology to lung cancer to for his of persons to be tested. the only to develop The use of of heightened susceptibility removal from asbestos the health hazards cooperation destined and should not be abandoned. distinguish quit smoking deserves workers medical screening remains assisting the unfortunate individuals exposure or for motivation Screening examinations of his develop job and may be used in improving work practices as well as remind to the to enlist in changing detrimental personal habits. It is suggested in asbestos workers chest X-rays, that programs consist facilities should be for early exposure that are identified from detection of to age, asbestos competent in risk of (see Table 7). the program to operation. proper check roentgenography, administered lung cancer, lung according and since cancer examinations, to a time elapsed Available medical localizing and resecting in advance of cancer detection of periodic sputum cytologic and symptom questionnaires schedule which varies with since first of to minimize Emphasis chest X-rays lung time cancer taken must be placed on alone should detect 95 DPMC-01600 LAM 008116 the majority detecting of lung tumors; centrally placed likely develop ’ sputum cytology tumors36 whereas peripheral lung cancers is more effective in asbestos workers may more (adenocarcinomas).41 film must be read independently by more Each chest than one physician especially trained to detect early lung cancer and qualified in the ILO/U/C classification of radiographs of pneumoconioses.^2 Laryngeal Cancer Asbestos workers with soreness of specialist the clinical symptoms throat should be referred for a detailed otolaryngologic respiratory of hoarseness to an ear, nose, examination of or pain or and throat the upper tract. Mesothelioma At present, mesotheliomas are uniformly modes of treatment may be harmful. able, screening for early detection beyond what may be done of no prolongs Neither radiation, lung cancer is nor chemotherapy fatal. surgery, survival; Since no useful clinical value. of Fecal occult-blood years a to detect Invasive diagnostic procedures to the relief testing has been used an an annual screening the stomach, lesser extent, tests have been obtained small intestine, Persons with positive results for further studies, biopsy, and radiology. and gastric cancer, stimulate bleeding referred from persons rectum, and, to lesions.46* to a gastroenter­ include endoscopy, cytology, Early detection and excision of a colorectal it has been noted, can be reduced filter paper slides should be which may high as 90%, compared with respectively.49,50 False positives colon and from persons with benign gastrointestinal ologist rates as and 10%, these avail­ colorectal cancer in asymptomatic men and women 40 old and older.Positive cancer of is the Alimentary Tract device to detect with radical fact, therapy should be kept to a minimum and.management restricted of pain and breathlessness .43,-44 Cancers in may result in 5-year survival overall national averages of 40% considerably by using guaiac-impregnated in conjunction with a diet high from existing lesions) and in residue free of red meat peroxidase foods (e.g., horseradish and beets). Vitamins containing medications should also be avoided.45,47,48 and (to and high aspirin- 96 LAM 008117 Asbestosis Periodic comparative (see Table 7) will improve Many abnormalities, to determine if chest X-rays however, these reflect smoking or aging.51 and pulmonary the chances of detecting Pleural are nonspecific, early asbestosis function tests early asbestosis. and it will be difficult or are merely thickening or plaques related to in an asbestos worker must always be suspected as evidence of a biological effect related to inhaled asbestos.52 Persons with early asbestosis or with pleural thickening should be removed to a chest physician from asbestos exposure and referred for careful follow up. 97 T,n‘ ■i < DPMC-01602 LAM 008118 Chapter VIII CONTROL OF THE ASBESTOS HAZARD—EDUCATION Asbestos was health standard the OSHA Act of (to change the subject issued by 1970. the But although the allowable airborne directive has been included visors of first occupational safety the Department of Labor, the standard has been amended since exposure concentration), regarding education or no specific training of super­ or employees. However, in standards subsequently carcinogens—including vinyl chloride, the National requirements specified for employee training and for example, the following: of the operation conditions Cancer promulgated the subject monograph by of and following passage of involving that may another control Institute*—there are particular nature indoctrination in, the carcinogenic hazard, the carcinogenic agent; release decontamination practices; for a number of of the agent; nature recognition of purpose and application of emergency practices and procedures and the employee's specific role in them; and purpose and application of the medical surveillance program.1 It would appear that a comparable mandate should Goals exist for work with asbestos. of Education Implicit genic hazard in the fundamental goal of from asbestos controlling are several goals of the human carcino­ education—increased knowledge of: • Work processes involving asbestos and the potential for fiber emissions • The physical characteristics its • Diseases how of asbestos, dispersion and potential for that may result these diseases advised from exposure is the control monograph Vinyl Chloride, mation presented regard to the to Sciences cancer; that read there complements embodies some of to asbestos fibers and 'Risk;'" Control" since some of the in infor­ the material presented here with review of study on informing workers and an outline of to understand the section on "Educational asbestos-control situation. there are "Understanding as are manifested The reader cancer so inhalation Among the topics discussed a National Academy of and employers about occupational an on-going vinyl chloride education program the approaches discussed here with regard to asbestos. 99 DPMC-01603 LAM 008119 • The • Reasons • concept of "risk" for, and methods of, The purpose and nature of methods as tion, discussed in environmental monitoring engineering and work practice control the previous personal protective devices chapter (exhaust ventila­ and clothing, personal hygiene etc.) • The elements of medical surveillance and • The role of related factors the reasons in disease production, for it such as smoking. Modes of Education—The Written and Of the two modalities written word and It lacks terest of employees then, concern, and Furthermore, the reading skills of of the instructor, discussion. employed in delivering health messages, the spoken word, the elements of at once it should be as the Spoken Word the written word is far warmth, and personal there is the efficacy the reader. a reinforcement to the same full of time can clarify medical and suggest changes inadequate information, communication will labor-management contracts perhaps most or by chosen rumor. give meaning to The test and life styles. take place at group education session: law.2 The subjects for presentation the occupational health staff; through joint personnel with department heads, nurtured by and such sessions may be required by selected solely by effective, terms, in work habits In some employment jurisdictions, may be mandated; the physician periodic medical then focused on one individual—one who is, physician at Most oral is when even communication foreboding and apprehensiveness, folk beliefs, results, to be used but, the employee's on reach hundreds the oral mode of misunderstanding, this in­ for question and if one must for oral communication Attention is time, the effective the written word depends the written word might have One good opportunity examination. of However, and an employee review the results of at dedication, no opportunity less or, consultation of health plant manager, and trade union offi­ cials . Education must go beyond a pro forma attempt to meet mandated requirements. As recommended by a special committee of the National Research Council,2 provision must be made for the worker to acquire more information material. answered, He, than is provided by the worker, if not during the "package" of educational must be assured the that his information session, questions will be then later by telephon 100 DPMC-01604 LAM 008120 letter, or consultation with a member of or someone equally An excellent tation of occasion tion forum for group health new employees. to discuss recently the occupational health staff education orien­ knowledgeable. The occupational health the purposes completed, to of during the should use the the preplacement medical examina­ describe available health services, explain engineering controls, work practices, tective equipment. Pursuit of a health facilitated by initial introduction. this is staff and use of problem in the and to personal pro­ future will be The Educators Persons from a variety of backgrounds may be involved tion effort—physcians, nurses, safety specialists, others. and health educators, in the educa­ industrial hygienists, Physicians Physicians learning, where that teach they can remain comfortable with a and oral shorthand. medical disorders stand, yet this specialists It and usually do so takes to a the charge of layman of higher technical lexicon greater effort and more risk factors must be in institutions time to describe in terms he can under­ the physician, particularly the in occupational medicine pulmonary disease. Pulmonary disease specialists, in particular, as they become more knowledgeable about asbestos-related diseases, must leagues in For in spite of a growing body pertinent of the medical and unsuspecting are members of opportunities as lay grams for literature, of, many diseases. physicians could assist Also, the Many col­ about, chest physicians and such membership can provide many the education of leaders. their remain uninformed asbestos-related diseases. lung associations, for community specialist community of inform fellow medical practitioners when necessary, as well the pulmonary disease occupational physician in educational pro­ industry. Nurses Health education has long been recognized as the occupational health nurse and an area considerable contribution. The nurse often has with the physician and the employee influence on advice of than does changing a primary in which she function of can make a a closer relationship therefore may have greater the employee-patient's behavior. the medical director might be interpreted as Whereas the the biased word 101 DPMC-01605 LAM 008121 of management, opportunity a skilled nurse utilizes for presenting material Health Educators Professionally in the medical problems "shop trained health facility, of may be industry. they have been able or concerns peculiar position to communicators programs to As to learn the health communicate successfully with the the mission of the work population, This background puts found in full-time personnel to become acquainted with work processes, patois." an to health behavior. (Communication Specialists) larger occupational health organization, every patient visit as relevant to and educator the identify to absorb the in an excellent the employee. Industrial Hygienists The industrial hygienist health staff. recognition, Whereas evaluation, mental hazards and evaluate, One aspect of this and control control physical hazards know to or the occupational expertise in relating the education of informs workers trained to themselves. the working com­ they in improving the work to can to min­ environment. Specialists a small but full-time staff persons increasing number of trade unions have in the area of occupational safety These individuals may be extremely influential, the issues is about measures them to do what the to environ­ industrial hygienist to assist Union Health and Safety health. the and motivates imize personal exposure and In recent years, of the environmental hazards responsibility is The industrial hygienist appointed an integral part control of diseases in the workplace, recognize, munity. is the occupational physician has because and they and supporting data well and can communicate information their locals by means of periodic letters, reprinted presentations.12 memoranda, newsletters, Industrial Safety and Other Training Specialists Ever since specialists the birth of the safety movement for employees. Although most of these efforts have trauma, some slight redirection could channel tion of asbestos-caused disease. In addition programs in the United States, in accident prevention have conducted educational programs to training in safety, in other subject matter, related them toward there may be company from management skills to physical the preven­ to training technical 102 DPMC-01606 LAM 008122 j| craft apprenticeship information. programs might also assist Training specialists who conduct such in health-hazard education. Science/Medical Writers Medical writers periodicals on the staffs might be asked of large daily newspapers to a plant to be made tent of a medical surveillance program, results, If and reports avenue education of Target Groups As and chances will be that the worker. there are many target in prevention of asbestos the employer and trade union officials, families, activities. improved the result could be yet another groups within disease is the employed and, retirees and miscellaneous industry needed. the OSHA occupational safety and health act of toward both the con­ health survey for Education indicated, instruction in evolves, are in-depth and accurate, for to be apprised of to be updated on general occupational health a good working relationship and other familiar with 1970 direct in addition, and other former workers, persons in the community at for whom The language training there are workers' large. Managerial and Supervisory Personnel Managers risks of should be as the materials tive measures, listed at is or even more familiar, their workers medical surveillance, the beginning of There familiar, they ask this and often an unusual climate in which That is, line managers have risen from the ranks, careers they, occupational health managers know of Their concern is while, at themselves, to of knowledge educate managers a number of executives so that at the the same great as time, fiber. literacy that familiar with aspects of Hence, any special attention because such that of newly their and inception of the latency period before manifestation of as the of Education." worked with asbestos procedure draws However, while they may know not be as "Goals with and with preven­ the other areas chapter under about asbestos-related disease. their to handle level is the fiber disease. employed mechanics' is hazardous, the problem as helpers, probably higher. they might they should be, and they should receive as much medical and industrial hygiene information as they can absorb. Because he is at the level of management closest a well-informed supervisor should be particularly to the worker, effective in 103 DPMC-01607 LAM 008123 modifying the behavior of workers motivate rather than commanding or since he will be in a position invoking the sanction of to regula­ tions . Workers in the Asbestos, While workers educational in efforts, asbestos and who, and how to minimize the asbestos Other, Trades trades are obvious targets of there are other workers who may be exposed therefore, it. and buildings, welders, machinists, as Well as should be informed of These workers painters, shipfitters, include those who dismantle ships electricians, machinists, to the asbestos hazard carpenters, and automotive brake marine and clutch repairmen. Retirees and Other Because of disease, it is the in manifestation of left work with asbestos that if he no no longer at risk of Exit interviews lance. else­ to depart with contact with the that material development asbestos-related diseases. to stress Wherever possible, in plant programs longer has and with to obtain employment provide an opportunity life-time contact and asbestos-related to maintain contact with retirees The asbestos worker cannot be permitted misapprehension he is long delay necessary persons who have where. Former Workers to emphasize the need for former asbestos workers of health education, the need for continued medical surveil­ smoking should be cessation, included and medical surveillance. Workers' Families In addition families of of smoking to learning about asbestos-related disease, asbestos workers should be cessation and about brought home on clothing, lunchboxes, mates. of Also, their employee-spouses office often ask more astute, Communication is fibers and it has been observed that at the plant r..ysician's more penetrating questions reinforced by the importance and automobiles, good with mixed audiences, prevention will be strongly the the potential contamination by equipment, in the form of souvenir ore samples. wives who visit with informed about and informed than their the program families. Occupational Health Professionals Because industries, turing, there are so many substances, levels of industry combinations (raw materials, of substances, intermediate manufac­ finished product manufacturing and distribution), occupational 104 LAM 008124 health personnel are not rently in use. all-knowing about all hazardous For example, with in innumerable buildings being it is possible that in the asbestos a project present i.e., personnel against the ubiquity professional's material's presence Assessment of Every health for is institution not inauguration of effects such that health personnel's parts the asbestos suspicion, fiber it could be knowledge— hazard will sharpen and he will seek out the the workplace. Value* • of to its worth. there are means by an education program might be judged. a work force as are leaving of or raw materials education program should be validated as a whole, some workers for other employment, informally before and after various participated as • the the untoward evaluation may not be possible, effectiveness some workers they throughout Education's While a rigorous Although index of cur­ insulation renovation or demolition, asbestos Information on the health substances asbestos a company or the reworking of asbestos-containing manufactured elsewhere. tested of in a plant without a company's the of industry may suddenly be faced with Finally, through which removed during the health personnel of to protect inhalation. the possibility are retiring and small groups can be education segments in which follows: Compliance in engineering controls without giving great visibility to workers could be observed prior program to determine if there engineering control devices and safe work practices— the check-off procedure, to and after is a change in the educational their use of or in their compliance with safe work practices. • Compliance in medical surveillance programs—workers often report for chest radiography or pulmonary function only after innumerable telephone calls proved compliance rate would indicate some success • Basic knowledge appropriate to and post-tested workers ability, test of target cultural differences but and im­ in education. group—groups can be pre- retention of common knowledge expected of in daily contact with asbestos. results, added for testing and notices, Differences in reading, and anxiety levels will influence there should be at least some rough indication information or altered behavior. 105 DPMC-01609 LAM 008125 APPENDICES DPMC-01610 lam 008126 Appendix A ASBESTOS-RELATED AND -ASSOCIATED MINERALS Minerals Other Than Asbestos Mineral Species Pyrophyllite that May Exhibit Fibrous Structure _ _ _ _ _ _ _ _ _ _Morphological Characteristics Sometimes occurs as crystals quartz veins Vermiculite kyanite, (a clay) fibrous in structure, varieties have been Commonly crystallizes Attapulgite and from reef mines. Normally exhibits a flaky fibrous but reported. in well-defined forms. Normally fibrous or granular when present Lepidolite (a mica) as overgrowths on muscovite micas. Minnesotaite (a radiating needlelike in feldspars, Commonly fibrous rather than platy. Sometimes occurs in the form of minute talc) Chamosite fibrous crystals, associated with sedi­ mentary iron formations Halloysite Frequently occurs with kaolinite and is (a clay) characterized by elongated tals, Holmquistite (an amphibole) Richterite similar tubular crys­ to needles. Commonly occurs in aggregates and some­ times displays an asbestiform texture. Commonly exhibits a (an amphibole) The first (ironstones) graphic habit three have important are found in connection with fibrous crystallo­ similar to asbestos. industrial applications; the others commercial mineral operations, where they are normally considered an impurity. A-l Tin:' DPMC-01611 LAM 008127 Minerals and Rocks Possibly Associated With Asbestos Mineral or Rock Talc3 Uses Ceramic applications (whiteware, wall tiles, electrical porcelain); extender for paints and pigments; and filler for cosmetics, lubricant and in the preparation and packaging of foods. Phlogopite A member of the mica family, used in a number of electric Chlorite A common constituent of metamorphic rocks; green coloration, due to its is used in construction for aesthetic purposes. Kaolinitic clays Used in ceramics (whitewares, thermal insulators); filler or extender in the rubber, paint, as a and plastics industries; in the paper industry to impart gloss, brightness, and printability; opacity, and in medications. Bentonitic clays Drilling muds; (Montmorillonite, filtering applications; Fuller's earth) pharmaceuticals, Vermiculite Used primarily in the construction industry as an insulator as a binder for iron ore pelletizing; and a filler for paints, in cosmetics, and ceramics. a but is also employed in the agricultural and horticultural industries as a soil conditioner. Taconite and simi- v c 0) Q. * A primary source of iron for the steel industry, lar metamorphic iron deposits Magnesite and Used as a raw material for magnesia-containing refractories, Brucite fluxes, and miscellaneous chemicals and can be used in the production of magnesium metal. with magnesite and, Marblec as such, Brucite is often associated is used as a source of magnesia. FEDERAL REGULATIONS OF OCCUPATIONAL EXPOSURE and electronic applications, such as insulation in air­ craft sparkplugs, and as a thermal insulator.b Metamorphic carbonate rock used for polished stone and other applications in construction and for sculpture ! aAlso known as steatite or soapstone. ^Most phlogopite is imported into the United States. Its occurrence in this country is resticted mostly to small, noncommercial deposits and as an impurity in certain marbles. c The term "marble" Is sometimes used indiscriminately to describe other rocks that can be polished and that have a pleasing appearance; such rocks include the so-called verde antique or serta green, some onyxs, and slates. Verde antique (serta green) is commonly a serpentine and is therefore likely to include chrysotile contaminants. Sources: W.A. Deer, N.W. Hendry, et al. "Rock-Forming Minerals," Longmans Green & Co., "The Geology, York Academy of Sciences, 1961 Occurrences and Major Uses of Asbestos," New 132, Dec. 31, 1965. Malcolm Ross, "Geology, Asbestos and Health," Environmental Health Perspectives, 9, Robert L. Bates, Publications, 1974, pp. 123-4. "Geology of the Industrial Rocks and Minerals," Dover Inc., N.Y., 1969. A-2 DPMC-01612 LAM 008128 ^ 83 1 O 4*i rs p ON o +. ^3 H > P 0) H4tH G G O 3 *H G 44 43 U ^2 4-1 43 G O P 72 G 72 <5 H G 60 G G 43 G • G 42 G *H >» 4J 42 P S3 >%rH G O P G 3 © G G G G © 3 to e c^ «H © rH P M 4) G JP u Sh 4h ffl h G © 72 g g m oo o; H P G P 42 P G 43 m O P 00 Q) ^ p 73 i O G 60 45 O C P *H •H Q> 44 4-1 CO g P P G O 3 PBt ° 60 iS G A G G m *4 B G i—1 42 G G *H M P. 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P •H 0 a *0 >> 0 *H O a *h p 0 *0 0 0 O *H *0 •0 •H P 00 t-H Q *0 a 0 a 0 0 0 P 0 0 >* 0 rH P m 0 -4* a *0 •H 0 0 *0 0 0 0 0 a 0 p >. >* 0 0 0 fL 0 O £ 0 44 vl 0 p O 0 0 4h O O 0 O rC U P o o 0 >* p p o p a 0 P< &S 0 0 p o p O 0 PCO 0 p «H a| 0 0 *0 Q cd I « 0 00 0 cl 0 0 CO 0 o p o 4-4 0 rH 0 O 0 O •H P 0 O 0 S 0 0 0 P O O Cd 6£ 0 0 Pd B-3 DPMC-01615 LAM 008131 Appendix C MONITORING AND MEASURING ASBESTOS Although diseases Is the role of asbestos clear, the mechanisms well understood, and this control human exposures economic difficultier of this murky: impedes to underlying disease causation are not efforts and, to measure As of measuring asbestos Which attrihute(s) disease and which a cause of cancer and other the substance. chapter—were not enough, (1) as CONTAMINATION technical and concentrations—the two other of asbestos if the that is hazardous, The attributes of asbestos subject facets of the hazard are it is that actually therefore must be measured accurately; amount of asbestos subsequently, and over what that have been and causes (2) the period of time. implicated in various A hypotheses on asbestos • carcinogenesis Size and shape of individual include: fibers 2 • Number of fibers • Total mass of asbestos • Type of asbestos • , 4 Trace metal content • Trace organic content • Surface charge • Surface adsorptive 3 2 6 characteristics 6 Because of the inordinate difficulties of separating the attributes from nonasbestos "background", these four are not indices of exposure for hypotheses based on trace metal or organic content have favor. Because cancer and, there therefore, routine monitoring situations. is no consensus on no measuring method will be ization of exposure the that which permits through measurement of and shape of individual and to asbestos, fibers; four suitable In addition, fallen out the attribute(s) consensus on the appropriate from environmental exposure last that of cause indicator of risk "best" monitoring and the most detailed the first number of fibers; character­ four variables—size total mass of asbestos; type of asbestos.* * References will be found at the end of this Appendix. C-l DPMC-01616 LAM 008132 In addition to the limitations established whether the time-course of exposure, significant in determining carcinogenic possibility that as just mentioned, to determine it may be just as risk. important must be chosen judiciously to fit the general environment; measurement versus monitoring the those in air; according to This to and because and costs of measurement discussed below, to or dose rate, leaves been is open the determine peak exposures time-weighted average exposures. Because of these limitations, exposures it has not yet the fiber type that the circumstances: Also, occupational concentrations environment at is technical difficulties the method of measuring of asbestos certain individuals. of in water large versus the methods versus determining chosen may differ of concern. Monitoring Devices and Methods The most desirable means of monitoring in general, which a device water, used or could measure directly in a bulk sample of for continuous the asbestos material. monitoring, is not in concentration in air, Such a device, available would be one which might for most be situations, however. Some Limited-Application Monitoring Devices Some devices for measuring general particulate contamination of fluids—based upon the piezoelectric balance, light-scattering principles'^—may be tions where the asbestos 8 Beta-attenuation, suitable concentration is 9 or for monitoring applica­ a known, constant, and relatively 11 large fraction of the general particulate appropriate for such \irposes community air, where orders of magnitude appropriate the greater in surveys of loading ratio and total contamination. They are not as asbestos-pollution monitoring in particulate loading will be than the asbestos industrial sites, loading. where the size of airborne asbestos 12 several Nor are they the asbestos/total fibers may fluctuate 2 markedly. and Thus, continuous monitoring is sampling will almost generally not practicable, always be necessary. C-2 DPMC-01617 LAM 008133 Monitoring by Membrane Filtration The major method of monitoring in use membrane air, filtration. stack gases, media, it The membrane water, food can be used as a for environmental media filter method is liquids, and other is directly applicable fluid media. final concentration step for fibers to With solid that remain after some preliminary digestion procedure. The procedure most commonly used is a single-step filtration, which all suspended particulate material in together with the suspended asbestos. utilize a dual-filter set-up first the larger material while allowing much of most of filter the asbestos) for analysis. advantages to pass 12 recommended because as the collection characteristics The fibers to be second filter (finer) some concentration are high, (including is low the method loading increases, change causing an increasing amount of trapped on the first filter. filter best-suited for use in most environmental sampling for asbestos to to be collected on the in which the asbestos to filter entraps smaller material of other particulate material cannot be generally asbestos the (coarser) however Although this dual-filter method has for applications and concentrations through the medium is entrapped, It is also possible, in which the in is those manufactured by pore size of 0.45 99.9% of asbestos a mixed cellulose-ester membrane the Millipore Corporation), or 0.8 pm. These fibers present 13 filters will (similar with a mean nominal remove, and are estimated filter from water, to be "...almost 14 100% efficient..." for removal of asbestos For some applications, the fibers from air. "Nuclepore" membrane filters manufactured 12 by General Electric are most appropriate. for scanning electron microscopy of relatively However, because flat They are more suitable collected samples because of their surface and their -relative stability in an electron beam. they are difficult they have to use in direct a high pressure drop at environmental monitoring, normal sampling rates and a 03 DPMC-01618 LAM 008134 tendency to develop static charges,which makes them difficult to handle * after sampling. Measuring Asbestos It is most probable attended by greater in Chapter exposure in Air III). that inhalation of airborne asbestos carcinogenic risk than is Hence, it is most to airborne asbestos, tion groups, be refined so as that ingestion important that a function of those groups discussed present knowledge time at (as is for various greatest of popula­ risk can be ascer­ tained. tics of The biologically effective concentration and deposition characteris­ of for inhalation the the particles individual) available are the biologically effective fiber number, size, with disease. of man) critical parameters concentration will be shape, mass, and the breathing zone to be measured. (deposition in correlated the airways are complex and are discussed elsewhere in this monograph that the diameter of controlling variable in deposition, should be measured, although this Measuring Asbestos special care if exposures. asbestos the Stream flow rates, is length is are there to be of are content distribution of asbestos thermal stratification, the distribution As studying part of this Research Laboratory has enough that both in a given body of water. sedimentation, as may the system. the Athens developed and differing (for drinking water) the question of measuring asbestos effort, requires seasonal effects on sources of The Environmental Measurements Advisory Committee of recently been the principal representative of potential human flow rates may all have an effect, characteristics important (Chapter III). difficult in practice. to determine asbestos results As with air, and on the but the individual fiber is of in Water The sampling of water water. The some complex function of type of asbestos best Deposition characteristics Suffice it to say source (in (Georgia) the EPA has in drinking Environmental a preliminary method for such assessment.* * For discussions References 14, of membrane 20, 24, 25, filtering that are much more and 26. thorough, see . DPMC-01619 LAM 008135 In part, "It the guidelines is beyond instruction the for given scope of are fibers, small, this procedure field sampling; waters are applicable. asbestos there include: considerations from .1 pm or more. sampling that type of particulate matter. and in water range range of size furnish detailed the general principles of There are some a special to apply These Because of to fibers the there may be a vertical distribution of particle sizes. This distribution will vary with depth depending upon the vertical distribution of conditions. of temperature as well as Sampling should the analysis. the local meteorological take place according to If a representative sample of a water supply is required a carefully designed set of samples representing the vertical as well as the horizontal distribution, and these samples should be bottle capable of holding at rinsed at prior to least two least one liter. times with the water that sampling. (Note: Glass vessels is should be being sampled suitable as sampling containers.) A minimum of approximately one liter of water is required and the sampling container should not be filled. It a membrane is desirable to obtain two filter and the samples in Food The most and yet is critical, a method from one location." it is filtered 15 through filter prepared further for analysis. Measuring Asbestos food to be used for separation of any asbestos rice) screw-capped The bottle are not When the bulk water sample has been collected, such taken, composited for analysis. The sampling container shall be a clean polyethylene, in the objective unresolved issue in measuring asbestos in preparing solid or semi-solid that may be contained. generally suitable method exists. Surface At food present, contamination (e.g. no on may be measured relatively easily by straightforward washing and filtration techniques. with membrane filters, For liquid foods and beverages, is often appropriate, remove organic co-contamination of the filter simple followed by filtration, treatment to surface."^ C-5 DPMC-01620 LAM 008136 Analysis of Samples—Some Technical and Economic most valid for complete assessment of The asbestos This analytical methods contamination are is particularly from air or water. true those methods based upon electron microscopy. for assessment of general In some cases, asbestos exposures where the to earlier, or community exposure fiber-size distributions are constant and already known the use of optical microscopy, referred Constraints of from electron microscopy, the methods of continuous monitoring may be justified for routine surveillance. Technical Constraints Individual asbestos optical microscopy. fibers can be identified by phase-contrast However, without using electron microscopy it always possible to distinguish asbestos (fibrous glass or mineral wool) , synthetic organic (nylon, monitoring situations orlon, fibers from amorphous natural organic etc.) the majority of fibers. is not inorganic (plant or animal") , Moreover, or in most fibers will be below the resolu-* • tion of the phase-contrast microscope. Complete characterization and ------------------------------------------------------------------------------------------------17, 18 identification of such fibers requires the following information: For samples such as fiber no type • Dimensions • Electron diffraction pattern • Elemental composition community air and water, cannot be ruled out simple matter. and morphology a priori, for which more obtaining this than one information is Each fiber must be identified separately by using electron microscopes,^ equipped with X-ray area electron diffraction capabilities, for fluorescence and selected the determination of elemental composition and crystallographic characteristics. With any of of the the analytical methods, relatively "heroic" techniques as filtrations—tend difficult ashing, Many of multiple transfers to subdivide fibers to reconstruct are necessary because sample-preparation methods required, for transmission electronic microscopy. such compromises the original of especially these methods--involving liquid resuspensions, into fibrils. Thus, size distribution. it is and often C-6 DPMC-01621 LAM 008137 For samples the in which the concentration of size distribution small, because only asbestos size distribution fibers is low and analysis may be unreliable a few fibers will be seen. Economic Constraints The equipment needed program will extensive required for complete analyses require a highly skilled and experienced operator and technical support. The minimum initial capital for new equipment will be in the and an annual operating budget of nearly This will cover the overhead expenses for a microscopist and is present, complex, the may require fibers and fringe benefits, two or three filter material costs may run to several If from photomicrographs, only upon recognition of for evaluation of Because of tion, there are the excessive— may be obtained sample and is more the sample 20 21 ’ but counting and sizing of these automated methods fibrous morphology and are are based therefore unsuitable type. Measurements difficulties large variations samples of air and water, of measuring asbestos-fiber in the measurement Asbestos in Water Although the attainment studies of an contamina­ of asbestos both within and among laboratories. replicability and duplicability analysis the thousand dollars, "mixed" exposure by fiber Reproducibility of is not type for analysis."^ Some progress has been made in automating the fibers, technicians. their size distributions few hundred dollars per sample. several weeks and sample—when only one and other particulate the number and mass of for a cost of a $100,000-$250,000, $100,000 will be required. and the salaries, For an uncomplicated membrane fiber range of investment expense of purchasing and installing a scanning/trans- mission electron microscope, of in a continuous monitoring in Several are summarized below. intralaboratory precision of -30% 18 it is not uncommon of water has been reported, in for results C-7 DPMC-01622 LAM 008138 from duplicate laboratories In a reproducibility liter case where on an study reported 29. million In another fibers fibers liter. seven study, laboratories to 9 million contain 7.5 million fibers one per liter, while reported in 1976, per liter. in each of two the other showed readings of investigators evaluated laboratories sites on Lake varied the average) fibers laboratory showed readings of that analyzed samples Superior. from 1.6 million to The averages ranged from about 50% to of for 78.7 million fibers .per The within-laboratory coefficient of variation divided by "competent" per liter. from five different the nine to sample, variation among and within nine water in 1975, five replicate analyses were made identical to 4.0 million to in independent showed readings of below-detection-limit laboratories 8. competent workers than an order of magnitude. for a water sample known In another 0.79 analyzed by to vary by more laboratories per samples 100%. (standard deviation 22 Asbestos in Air There asbestos is also considerable variability concentrations, among laboratories. samples No one Sinai group These results, order of were air, two ten ambient the Mount Sinai Department of laboratories may be laboratory's also conducted reported state The and air Environmental given in Table two orders replicate analyses of authors the study in which The four samples. show differences of of C-l of magnitude readings were consistently higher. shown in Table C-2, magnitude. of atmospheric both within the California Department of Health are Differences between the or more. ambient Data on duplicate analyses of from measurements by Medicine and Mount especially of in measurements less these than art findings that an individual value may be accurate within a 23 factor of The two or three of inaccuracy in values obtained result from several number of tion fibrils in volume of bundles, a sample mean. (4) circumstances: found in these variability and (5) low-level its preparation and (1) from a specific statistical variation in given grid squares, fibrils, (3) incomplete (2) the can the a much greater varia­ dispersal of chrysotile in the amount of material contamination of analysis lost sample at various during processing, points during analysis. C-B LAIW 008139 Table DUPLICATE ANALYSIS OF TEN AMBIENT AIR Asbestos Sample Number Mount C-l Concentration SAMPLES (nanograms/meter Calif.Dept, Sinai of 74-000-003 0.6 120.0 74-000-012 44.0 0.4 74-000-023 0.0 13.0 74-000-032 2.7 0.0 73-003-038 2.6 0.0 73-003-046 7.3a 73-003-054 7.3 0.0 73-003-064 21.0 0.0 74-000-110 46.0 14.0 74-000-119 1.4 2.2 ^ith an annotation: "Disregard, Source: (end Reference 23 of this ) Health <800.0 only 2 fibers observed." Appendix). C-9 DPMC-01624 LAM 008140 Table REPLICATE ANALYSIS C-2 OF FOUR AMBIENT AIR SAMPLES 3 Asbestos Sample Number 1st Concentration Analysis (nanograms/meter ) 2nd Analysis Average 73-003-038 0.0 5.3 2.6 73-003-046 7.6 7.1 7.3 73-003-054 3.2 11.4 7.3 73-003-064 12.0 30.0 21.0 Source: Reference Although to be useful coefficient reported be a the for 23 (end this phase-contrast evaluation of of variation for of trained microscopic method has occupational (for sampling and technicians, two-fold variation between experienced and novice Appendix). 24 it results microscopists asbestos analysis) should (for be been demonstrated exposures, and a of been 22% has recognized reference for amosite, and that samples) a there may from four-fold 25 variation for fraction of in using each in a It sample method will by Conversions Fibers fibers this type) chrysotile. the of vary by particular Between also important airborne type industrial of to asbestos asbestos process Counts by Different Methods large variations recognize that and that will be also the visible (within being evaluated. and Between Number of and Mass. Because possible to of the convert counts by the equivalent electron microscopic of Indications error. acceptance of any a is study of size of constant the phase-contrast counts, error factor distributions for in measurements, optical is generally method not to except within very wide margins that may be for it introduced by uncritical conversion may be airborne asbestos found in exposures in (a) C-10 DPMC-01625 LAM 008141 [ various asbestos processes microscopic methods buildings. 23 In applied the be can counts were one job at plants, order it is clear comparison of of optical and taken by electron from inside public factors of 20-30, and no found. dust particles by determined by the counts; limits measurements Within a but of the midget impinger method phase-contrast microscopy, 26 textile plants impinger that air variations study which gives four asbestos increased with midget a study, levels in another (2) samples of visible equated with fiber illustrated to latter apparent correlation, Nor and if of both methods plant, comparisons asbestos are made as for levels across uncertainty are approximately an of magnitude. In a 1974 tude between plants study, there were differences fiber/mass and mills, ratios making any in emission attempt to of several orders streams apply of asbestos a constant of magni­ processing conversion factor 26 between number and Some • important The • fibers ratios and mass conclusions fibers general environment, universal scope can be drawn: of electron-microscope-visible visible No uncertain at best. results monograph, vary among plant ratios to as or well occupational for fiber a factor levels estimate the workplace, these of results 50 has exist. been that 2% of The total factor used fibers is are the micro­ In this to convert from optical-microscope-visible fibers. and categories. conversion of optical electron microscope electron-microscope-visible conservative emissions, optical-microscope- as within each of factors when needed, to based to on a optical-microscope- visible. • No single factor for conversion of mass emissions to fiber emissions the to exists. • Fiber/mass general ratios environments, environment. per data differ markedly The and number nanogram might well available and for from they also of occupational differ markedly within electron-microscope-visible range from 100-10,000. convenience sake, 1000 Based fibers on per the each fibers the observed nanogram C-ll DPMC-01626 LAM 008142 has heen used in and • 250 fihers this monograph for per nanogram for ambient The monitoring method but must • and of fiber size that these indices distribution means and standard that can be for fiber application directly calculated from asbestos and number, it be recorded whenever possible. can be deviations each a reference method. electron-microscope-visible fiber size recommended ing chosen will be different asbestos near plants, urban air. depend upon electron microscopy as Because mass type atmospheric levels completely of fiber stated by length length and diameter vary the is The geometric and diameter, independently of assum­ each other. REFERENCES 1. Stanton MF, in the rat 587-603, 2. Gibbs et al: Carcinogencity in relation to fiber of fibrous dimension. Cancer response 58(3): of airborne asbestos fibers 1977. GW, Hwang CY: 36(6):459-466, SRI pleural Inst Physical parameters in various work environments—preliminary 3. glass: J Nat findings. Am Ind Hyg Assn J 1975. International: Personal communication with Nicholson WJ, October 1976. 4. 5. Cralley U, Keenan RG, of asbestos textile products. Harrison JS, and 6. Gorski CH, Sem GJ, ment. 9. Soloman M, Dept. NIOSH, July of Need K: asbestos for and of A new mass Education fibers 1965. energetics of asbestos Feasibility Sciences, sensor 3(11):791-800, Carson GA: 1967. minerals. 1974. A of Controls Washington, of Asbestos D.C., 1971. for respirable dust measure­ 1975. theoretical direct-reading particulate mass Health, in the manufacture 28(.5) :452-461, carcinogenesis of The surface National Academy Tsurubayaski a portable U.S. The to metals Ann NY Acad Sci 132:439-450, 35(6):345-353, Am Ind Hyg Assn J Almlch B, of (Ed.): Pollution. Exposure Am Ind Hyg Assn J Studies Stettler LE: Hyg Assn J Cooper WC Air 8. FLC: their natural oils. Am Ind 7. Roe Lynch JR: and Welfare, and laboratory evaluation concentration instrument. Public Health Service, CDC, 1975. C-12 DPMC-01627 LAM 008143 10. Mercer, TT: Press, 11. Harwood CF: Illinois #71-8, 12. Aerosol Technology New York, Asbestos Institute Spumey KR, et Air Pollution Control. Manalan DA: 26(5): 496-498, Asbestos Puerto Rico, 15. Lynch JR, April of Nuclepore Anderson Measurement GA, Ewell JB: on Techniques Chicago, ITT Research The 20. analysis. Beaman DR, File 21. Paylidis T, October 23. AL, April III). Proceedings 181-186, 1975. asbestos counting of 8-11, The in water. fiber 9: and quanti­ 133-136, 1974. Ann Occup Hyg 16(4): 3rd Joint Conf Carter RE: fiber concentration of the SEM. 1976. evaluation. Nov. in to identification Hie automatic the the dust with electron microscop Environ Health Perspect Presented at Taylor WF, 101-110, dust to and biologicals. 1976. constraints fiber. IEEE Computer Society, Jr. (Part drugs Chem 48(1): Steiglitz K: amphibole food, Quantiative determination of and Fibrous 1976. DM: Airborne asbestos 1973. in Ann Occup Hyg 13(3): Harness 397-404, 1976 Institute, asbestos of the J Occup Med for Particulate Matter Studies Approaches Brown, at Dorado Beach, for Determining Anal in air samples. 22. exposure. July 28, contaminants fication of nition, Inc., Environmental Protection Agency, Langer AM: I: asbestos identification of asbestos microprobe concentration. 19. of Interim Procedure U.S. Scanning Electron Microscopy 18. Presented Application of electron microscopy Workshop FD: filter. Drug Association, Research Laboratory, problem of particulate Pooley asbestos Air Pollut 1974. A Preliminary Athens, Environmental 17. J 1968. CH: McGrath PP, filters. 1976. removal by membrane 5, Ayer HE: 21-24, Asbestos. 16. State of 11 EO Document The sampling and electron microscopy of air by means Spring meeting of the Parenteral 10(1): Chicago, for Environmental Quality, al: in ambient Control Assoc 14. Academic 1971. aerosol 13. In Hazard Evaluation, 1973. asbestos on Pattern fibers Recog­ 1976. reliability of measures Environ Res 12(2): 150-160, 1976. Nicholson WJ, et al: Asbestos Buildings. Research Agency Pub. #450/3-76/004, Contamination of Triangle Park, Oct. NC, U.S. the Air in Public Environmental Protection 1975. C-13 DPMC-01628 LAM 008144 24. Leidel NA, Bayer SG, Zumwalde RD: Evaluating Airborne Asbestos NIOSH, 25. TN Beckett 84, ST, 27. Attfield Ayer HE, Lynch JF, membrane filter plants. Ann NY Acad MD: Inter-laboratory fibers. CF, Control Technology Ann Occup Fanney JH: techniques Harwood Triangle U.S. Public Health for Service, 1973. counting of asbestos 26. Membrane Filter Method Fibers. Sci Siebert P, 132:274-287, U.S. #650/2-74/008, Oct 1974. of 17(2):85-96, A comparison of Blazsak TP: NC, comparisons impinger for evaluating air samples in the 1974. and asbestos 1965. Assessment for Enclosed Asbestos Park, Hyg of Sources. Particle Research Environmental Protection Agency Pub C-14 DPMC-01629 LAM 008145 Appendix D ANIMAL STUDIES RELATED TO CARCINOGENIC EFFECTS OF FIBERS Inhalation Mice Hybrid mice chrysotile dust (AC/F^) at were exposed a concentration of week for 17 months or 58/127), a commercial preparation of 150-500 mppcf and were sacrificed of multiple pulmonary adenomas* was (45.7%, to after exposure. observed than in controls 40-60 hours (36.0%, in A high the exposed per incidence group or 80/222).160rf Rats White rats, some of whom had received an intratracheal application of caustic, (reportedly to chrysotile dust to 30 hours impede mucociliary clearance), per week for 62 weeks at were exposed a mean concentration 3 of 86 mg/m malignanat . Of thoracic fibrosarcomas, was twice as among 72 rats and surviving tumors 16 months or more, 25 developed (adenocarcinomas, squamous cell a mesothelioma). The incidence of great among caustic-treated those who had not been treated tumors in 39 caustic-treated and Squamous carcinomas of survivors (10/41 or untreated the lung were animals with cancer (15/31 or 24%). 48%) as There were no control animals. found carcinomas, in 2 of 113 31 Charles River- 3 CD rats 16 hours rats surviving exposure a week for exposed to two to years. chrysotile crocidolite at a concentration of No malignant or amosite, but 5 49 mg/m tumors were observed among of 40 exposed to chrysotile 106 developed multiple pulmonary adenomas. *Benign tumors +Chapter III of the lung. references—see Apendix H. D-l DPMC-01630 LAM 008146 Groups of 69 Charles River CD rats were exposed to crocidolite, 3 amosite, or chrysotile at mean per week for two years. developed malignant carcinoma) . cancers Among lung Three of Two the and , exposed . 115 chrysotile. to produced a 5% crocidolite. exposed (squamous exposed carcinomas (a cell to exposure fibrosarcoma, squamous for a While mass 14% and cell in and the concentrations of the the thoracic a papillary two years groups group three an adeno­ animals to among four a pleural meso­ and six months incidence among 16 hours crocidolite, amosite developed thoracic malignancies but 50 mg/m carcinomas mesothelioma developed experiment, amosite, to group a incidence of chrysotile and the carcinoma, one pleural In a similar to group pulmonary carcinoma) about tumors (a broncoalveolar thelioma) . concentrations of exposed to exposed types of asbestos 3 were and all about 50 mg/m 1105 million per , centration of 3 12 mg/m of All removal of the theliomas were and rats were chrysotile respirable fiber rats from found in optically visible respectively. C/D Wistar crocidolite, exposure. of cubic meter, In another study, phyllite, counts types 7 crocidolite. malignant tumors among control groups Forty percent of the hours to animals lung and pleura. each of observed duration of observed malignancies. As produce and carcinomas ly more asbestosis into account) tumors. amosite, antho- at a for varying conlengths and the pleural meso­ four fiber types, exposed exposed for developed No cancers were such two years found animals.^ increasing lung 864, among animals A dose-response relationship between asbestos with 54, which progressed after Lung carcinomas exposed of to per day produced asbestosis, and a single peritoneal mesothelioma was to exposed (Canadian or Rhodesian) dust the dust. fibers were 114 (taking among animals In addition, among exposure little as there was one-day an with lung groups asbestosis tumors exposed cancer was increasing exposure was pleural mesotheliomas. severity of and length than among for only one incidence sufficient There was and noted— of to significant­ of survival those without day, there were D-2 'Sr DPMC-01631 LAM 008147 significantly more lung tumors those without asbestosis.^ Intratracheal Injection among animals with asbestosis than among Rats White rats received 3.5 mg chrysotile of 19 developed 1, 2, in aqueous 3, 4, or 6 intratrachael suspension. Among pulmonary adenocarcinomas. Two injections 16-month of of survivors, these had 3 received 113 4 intratracheal injections, After administration and one had of 3 received 6 injections 0.14 mg benzo(a)pyrene (a carcinogen in intervals, injection of 2 mg or a single lung papillomas, epidermoid mesotheliomas were noted 28 months. 2 mg No tumors carcinomas, in 6/21 occured chrysotile alone or in and in 19 rats 2 mg chrysotile cigarette smoke) chrysotile and animals, 5 mg benzo(a)pyrene, and pleural respectively, given 3 monthly administered a containing at monthly reticulosarcomas, 6/11 49 rats of injections. within injections of single dose of 5 mg benzo(a)pyrene. Hamsters Eight pulmonary adenomas, 9 pulmonary carcinomas developed among 31 LVG/LAK hamsters 4.5 benzo(a)pyrene and 12 mg chrysotile over a period of dose No of tumors were observed Among 34 in 17 tracheobronchial papillomas, animals receiving benzo(a)pyrene administered alone, 9 and 6 receiving a 12 weeks. chrysotile alone. tracheobronchial papillomas 161 and 1 pulmonary The effect subcutaneous carcinoma were of intratracheal administration of in Syrian golden hamsters. tube twice weekly NDEA was injected 42 mg). One for instillation of 20 weeks once mg chrysotile asbestos after the start of NDEA was (total dose subcutaneously for asbestos with oral or nitrosodiethylamine Aqueous intratracheally once weekly one month reported. (NDEA) was studied administered per gastric 60 mg), a week for or 3.5 mg aqueous 12 weeks (total dose, in polyglucin suspension was 6 weeks (total dose, NDEA treatment. After 6 mg), injected beginning 8-10 months of 21/52 D-3 DPMC-01632 LAM 008148 and 14/51 the groups tively. animals developed benign and malignant receiving Among or asbestos control alone, Intrapleural asbestos groups only 1/50, and oral NDEA or pulmonary tumors subcutaneous NDEA, receiving oral NDEA, 3/47, and subcutaneous among respec­ NDEA, 0/50 developed pulmonary tumors. 162 Injection Mice Two of 75 BALB/c mice receiving crocidolite in aqueous intrapleural inoculations suspension developed pleural tumors, of but 10 mg no 163 tumors were observed among 75 mice injected with 10 mg chrysotlle. Rats A single dose chrysotile an as 20 mg of from various incidence of little of crocidolite, sources administered pleural mesothelioma 0.5 mg chrysotile or amosite, ranging to anthophyllite, CD Wistar from 19% crocidolite was to rats produced 70%. Yet to induce sufficient or as mesotheliomas. 3<77 Various pleural ICI asbestos injection types have induced mesotheliomas in Osbome-Mendel, Sprague-Dawley, following intra­ CFY and Wistar/Alderly rats.107*108'161’163 The carcinogenic response to chrysotile and 107,117 crocidolite appeared thus to be dose-related Oil-extracted asbestos casting doubt upon gave results the hypothesis similar to untreated that natural oils samples,107,164 and waxes, 166,167 contaminant oils from the milling process or organic materials 168 originating from storage in plastic carcinogenicity of or jute bags contribute to the asbestos. It has also been suggested that metal contaminants added during 113 Subsequent fiber play a experiments ment with acid, metal fibers base, contaminants; not exposed in asbestos using rats and (2) to role ’ carcinogenesis. have demonstrated ethylene diamine selecting asbestos that (1) treat­ tetra-ascetic acid to samples interior containminating hammermills; from among or (3) remove using different D-4 DPMC-01633 LAM 008149 • processing of samples of the same trace metals did not heating samples loss of for diameter determinants of type produce at activity and in addition to le individually mixture. each subsample of mesotheliomas ence material. superfine cial The highest Eight Cancer) chrysotile were milled higher yield By way of in to a a of contrast, substantial tumor yield rats important of U.I.C.C. reference Canadian finer powder of may be subsamples intrapleurally in Wistar Carcinogenicity was shape, standard chrysotile prepared by water asbestos. quantities in rats.'*'^ potency. Contre Injection of tumor yields. 900-1000°C resulted length, carcinogenic Internationale containing different different two hours carcinogenic Fiber (Union asbestos resulted than did all was than the the standard in a pooled refer­ produced by a sedimentation of Grade correlated with number 7 of separate commer­ fibers 107 less than 0.5pm in diameter On the other hand, pleura of considered to be By contrast, after Injection" below), of effective fibers less in mind Guinea Pigs, Pleural mesotheliomas intrapleural injection of crocidolite. An apparent chrysolite, with 0, injection of 1, 10, the majority long. less coated pledget than 0.2pm and in pulverized than injection that glass (see reduced of were greater thus size. "Intraperitoneal fully potent in prolonged milling may alter and the length 5-10pm, specimens, fibers to influence biological inducing the effects. and Rabbits developed 10 mg in Golden Syrian hamsters chrysotile, amosite, and 9 Or 25 mg, mesotheliomas fibers respectively. to induced among observed 50 dimensions, or for animals Prolonged milling, submicroscopic after anthophyllite, dose-response relationship was 4, of a than 5pm long were structure of asbestos Hamsters, of carcinogens intraperitoneal It must be kept crystalline diameter in greater numbers less than 10pm pulverizing asbestos before applying it Fibers which were present reduced greater Osborne-Mendel rats by means carcinogenicity. tumors. and by which eliminated 109 carcinogenic effects and greatly reduced fibrogenic activity. D-5 DPMC-01634 LAM 008150 One 10 mg pleural crocidolite a similar Of 16 mg one tumor was 3 group in an aqueous suspension, rabbits surviving at 2 18 months Injection least (Mice 12 months of injection with Dawley, and Wistar rats and observed in following injection with one at 22 and 10 mg in 20 were reported tumors groups injection to chrysotile as four 40 animals observation of opposed to 25 mg injections than 5pm long), standard chrysotile Subcutaneous of (2+5/17, injections 5 weeks. No of was for the or River CD, 6 the incidence of virtually identical, earliest tumor was mg chrysotile. of powdered (12/37, CBA mice developed inguinal 343 although Injection mesotheliomas the in Charles River CD and Wistar rats chrysotile.106,110,172 Although of 60 BALB/c mice within intraperitoneal injection of in Charles injection of among of crocidolite. following colite^*’^^',l‘^,^2 and Rats) occured Peritoneal mesotheliomas vals but none were developed pleural mesotheliomas, Peritoneal mesotheliomas less inoculated with 24 months. Intraperitoneal by guinea pigs inoculated with chrysotile. crocidolite, at observed among 50 chrysotile vs. 18/33, crocifollowing peritoneal the days time for from 25 mg Tumors were produced (99.8%) incidence was 32%, 276 Sprague of somewhat or 55%). the less fibers than for 119 (Mice and Rats) injection-site sarcomas 2+2/13, 10 mg 1+1/12) after crocidolite, tumors were and pleural and peritoneal three amosite, observed among 15 sets or of bilateral chrysotile at controls inter­ injected with 174 saline. findings The investigators, and believe jected directly into these cavities A single chrysotile to that, in their have been unable experiments, the pleural or peritoneal through local however, the overlying tumor was 33 Wistar rats. tissues. observed to asbestos cavities duplicate either was or ulcerated their in­ into 175 following injection of 75 mg 112 D-6 DPMC-01635 LAM 008151 JJ Oral Administration One fed gastric 100 mg/day (Rats and Hamsters) leiomyosarcoma developed among chrysotile 5 days 32 Wistar per week for 100 days SPF rats in a 6-month 176 period. No Among tumor 42 containing occurred among animals examined carcinomas, cholangiomas, also noted. 2 this carcinomas study of as regards the chrysotile or a diet for tumors their asbestos to of fed containing lesions which, the than 4 the liver adenoma, 2 fibroadenomas were group <0.01) fed of 702 occurred. asbestos The filter > however, the meaning since asbestos comprised chrysotile, Groups of once weekly when the gastrointestinal a diet containing 1% 5% by weight, 28-35 for rats 16 or compared with a for fed 21 10 mg 18 weeks control de­ group, 10 tract were observed chrysotile or in groups of amosite by weight lifespans. Mineral but in (p ingested asbestos. Carcinogenicity of genic by lung and fibroadenomas is uncertain crocidolite in butter related 45 hamsters tumors 4 kidney surviving an average 5 mammary develop malignancies. veloped no malignant No 2 mammary controls and 1 (52.6% filter material administered. fed did not could be and on a diet filter material sarcomas, including statistically significant Ten rats months tumors untreated 441 days tumors were observed: reticulum cell incidence of malignant only half day asbestos stomach papillomas, Among 49 material was of 2 3 Seven benign liver cell increased after an average of 12 malignant 1 lung carcinoma, carcinomas. days, controls. 50 mg/kg body weight per chrysotile asbestos), cell 16 fibers the other than asbestos have been intrapleural or only when of Other Mineral Fibers intraperitoneal a diameter similar to that shown routes of of to be carcino­ administration— asbestos fibers (less 5ym)• In groups of 32 rats, intrapleurally with inated with fibrous chrysotile, in mesotheliomas brucite 3 of or those occurred in 18 of those "nemalite," which may be injected with a ceramic injected contam­ fiber, D-7 DPMC-01636 LAM 008152 and in 1 powder, tors, each of and 25 mg, perhaps because talc, Gypsum, it biotite, relationship was 2 mg, 10 mg, (21/73), 53% (44/77), among control and in although dissolves injection of 72 of barium sulfate, in tumors fibrous, tissue. hematite) observed and 2 doses 71% (55/77), of in about 25 Non-fibrous glass of glass investiga­ injection of mg and 4 doses 75% of Wistar gave a low produced for team of intraperitoneal and nemalite—3 doses respectively—resulted 25/34). response results were noted: (attapulgite) (26/34, sanidine, injected with fibers aluminum oxide.In studies by another the following palygorscite of those tumor yield dusts few or no rats (3/35), (pectolite, tumors. A dose- fibers—intraperitoneal 25 mg results respectively. in No tumors tumors in 27% appeared animals. D-8 DPMC-01637 LAM 008153 Appendix E AIR AND DRINKING WATER ASBESTOS CONCENTRATIONS FROM SOME PUBLISHED STUDIES Table Atmospheric E-l Concentrations In Some U.S. of Concentration (Nanograms/m^) Average Berkeley, Boston, Dayton, EL Frankfort, Los (freeway) Angeles (control) New York City, Manhattan, Queens, Staten NY 67 6 0.4-11 14 0.09 0.02-0.15 14 5 4-6 14 27a Island, NY PA Port Allegany, PA 6-39 32 2-25 32 3-18 32 5-14 32 2-8 14 45-100 15 10-20 15 15 15 25 8.7-68 67 21 1.6-40 14 CA DC identified as 8a 70a 15a 20a PA San Francisco, Washington, 32 4 PA Philadelphia, Ridgewood, 8-65 9a NY Pittsburgh, 67 12** NY chrysotile 13 8.2-41 13.2 19a NY 13 43a 30a NY 67 67 KY Angeles Bronx, 2.1-12 9.5-200 TX Brooklyn, Reference) 24 OH Houston, Range Source (Chapter V 5.0 MA Chicago, Los 6.8 CA Asbestos Urban Areas asbestos by the authors. 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LAM 008157 M-l u Or^OOO‘AOf'>OOO'©C0OOOOOOOOOv0 «■ *4- *4” CM o s> o 00 • o 1 CO 4• o U O cO *H d) CM 1 00 ON • o u a iH oo m hj O tH C/3 O O CO O • • • • CO • • CO rtoooo^ooa CO • • • O 53 O -4- O H z g ^ o > AJ M P5 H P5 0) o «s c AJ 0) i-1 z 25 z H CO •H H C Q) a H H > 00 H P> *H rH CO z M P* H rH a #> * #« o A iH H H •H . M h a) A cd cd CO M H Z *■ i—l cd > <3 p». T3 X! o H - H i >4 H H P, 0) 00 00 iH H a X* tH W CO £ * iH o o *H 01 tH <1> rH « C < n o H a AJ O rH OH Id 3 &8 4J AJ AJ AJ «■> r£3 AJ 03 AJ CO g 03 cd P d ^ < H S S S CH z O •« • ^ a at c f (III) 37. Nurminen.M: A study of the mortality of workers in an anthophyllite asbestos factory in Finland. Work Environ Health 9: 112-118, 1972. 38. McDonald JC, et al: The health' of chrysotile asbestos mine and mill workers of Quebec. Arch Environ Hlth 28: 61-68, 1974. 39. Newhouse ML: Asbestos in the work place and the community. Occup Hyg 16: 97-107, 1973. Ann 40. 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Chapter IV 1. Daley AR, Zupko AJ, Hebb JL: Technological feasibility and economic impact of 0SHA proposed revision to the absestos standard. Roy F. Weston Environmental Consultants-Deslgners, March 1976 (prepared foi Asbestos Information Association/North America). 2. Schutz LA, Bank W, Weems G: Airborne asbestos fiber concentrations in asbestos mines and mills in the United States. U.S. Bureau of Mines Health and Safety Program Technical Progress Report No. 72, June 1973. H-14 DPMC-01672 LAM 008188 | (IV) 3. Dement JM, Zumwalde RD, Wallingford KM: Asbestos fiber exposures in a hard rock gold mine. Ann NY Acad Sci 271: 345-352, 1976. 4. Kleinfeld M, Messite J, Langer AM: A study of workers exposed to asbe8tiform minerals in commercial talc manufacture. Environ Res 6: 132-143, 1973. 5. Gidley MD, SRI International. 6. Curtis RA, Bierbaum PJ: Technological feasibility of the 2 fibers/cc asbestos standard in asbestos textile facilities. Am Ind Hyg Assoc J 36(2): 115-125, 1975i 7. 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