Document 6RBe803vNJw49G2o7o42VaYQ3

Handling Asbestos Chrysotile Asbestos in Plastics John L. Myers Union Carbide Corporation** A2 ] 1 7b Asbestos has received a great deal of attention and publicity in recent years, especially after it was designated a "target health hazard" by OSHA and a "hazardous air pollutant" by the EPA. Many of the articles on asbestos by the press have been emotionally oriented or distorted and, in some cases, stories have been sensationalized, based on obvious misinterpretation of facts. The use of half-truths or unsubstantiated statements has led to general con fusion and the unfair castigation of asbestos and products containing asbestos. The purpose of this paper is to put the matter of asbestos use and asbestos hazards into a logical and practical perspective. In this paper, the different types of asbestos and their many uses are discussed, along with government regulations controlling the use of asbestos. The health hazards associated with asbestos, both occupational and environmental, and some industrial ex perience with air sampling and dust control measures are also covered. KEY WORDS: Asbestos; Plastics; Air pollution; Toxicology. What is Asbestos? Asbestos is a commercial or generic term used to describe six naturally occurring "asbestiform" minerals that are fibrous, hydrated metal silicates. The six varieties are divided into two classes--serpentine and amphibole-- based on their crystal structure. Chrysotile is the only member of the serpentine class, while the amphiboles include croddolite, amosite, anthophyllite, tremolite, and actinolite. Chrysotile is by far the most-used variety and accounts for over 95% of U.S. consumption, as noted in Table 1. Croddolite, also known as blue as bestos, is imported from South Africa. Because of its high mechanical strength and good resistance to acids and alkalis, it is used to reinforce a limited variety of plastics where its pronounced color is not objectionable. Amosite, also imported from South Africa, is used primarily in thermal Presented at the Golden Gate Society's Man agement Seminar held in San Francisco, Calif., June 16, 1975. * Metals Div., Niagara Falls, N.Y. 14302. insulation. Although there are some deposits of anthophyllite in the U.S., most of it is imported from Finland. It is used primarily as a filler for polypropylene and in insulating ma terials. A comparison of the four varieties of asbestos which are of oommerdal importance is presented in Table 2. It should be noted that there are significant differences between chrysotile and amphiboles with regard to chemical composition and certain physical properties. Where is Asbestos Used and Why? Asbestos has served mankind for more than 100 years in a broad vari ety of applications. The general areas in which asbestos is used in the U.S. are shown in Table 3. Based on infor mation from asbestos producers and consumption surveys, it is estimated that the plastics industry uses about 33% of the 800,000 tons consumed an nually, which makes it the largest single user of asbestos fiber. The largest uses of asbestos by the plastics industry are in vinyl-asbestos floor tile and in phenolic molding compounds. It is also used in other plastics such as polypropylene, poly ester, nylon, melamine, epoxy, sili cone, and vinyl. Asbestos provides a valuable function in such products as brake linings, clutch facings, electrical components, automotive parts, furni ture, boats, sealants, coatings, adhe sives and mastics. The most important functions of asbestos in plastics are re inforcement, dimensional stability, heat resistance, flow control, and gen eral-purpose filling. Most of the func tions are supplied by short-fiber chrysotile asbestos fiber, although longer chrysotile fibers and other as bestos varieties are sometimes re quired for particular properties. Why Use Chrysotile? Among the several advantages of chrysotile, which set it apart from the amphibole minerals and account for its widespread and increasing us age, are world-wide availability, me chanical strength, flexibility, positive surface charge, low iron content, soft ness, and low refractive index. It is conservatively estimated that chryso tile asbestos is used in over 3,000 ap plications and, in most of these appli cations, it is an essential ingredient for which no replacement is readily available. The information in Table 1 shows that the use of chrysotile asbestos and its share of the total market are stead ily increasing. This is due partly to technical advances permitting the broader use of chrysotile in plastics and the general decline in the use of asbestos in certain fireproofing and in sulating materials. In addition, there is increasing evidence that croddolite and amosite are more hazardous to A Journal of Paint Technology Reprint :TC 009357 Year 1967 1968 1969 1970 1971 1972 Table 1--Apparent U.S. Consumption of Asbestos, Tons* Total Chrysotile Amosite Crocidolite 720,583 817,363 784,321 728,131 758,571 808,554 686,044 (95)11 775,711 (95) 749,708 (96) 695,770 (96) 729,272 (96) 791,020(98) 12,558(1.7) 20,467 (2.5) 14,618(1.9) 14,261 (2.0) 14,580(1.9) 7.125(0.9) 14,917(2.1) 13,965(1.7) 10,558 (1.3) 8,936(13) 6,953 (0.9) 5,374 (0.7) (a) Information based on import and production data from U. $. Bureau of Mines' Minerals Yearbooks. (b) Percent of total shown in parentheses. Table 3--Apparent U.S. Consumption of Asbestos By General Use Areas Area of Use Percent of Consumption Construction Floor tile Felt paper Friction and packing Insulation Textiles Other 40 15 15 14 3 2 11 human health than chrysotile.1 Since 1970, the use of crocidolite in Britain has been restricted after a panel of experts "concluded there was suffi cient evidence to suggest other types of fibre should be substituted for crocidolite wherever possible."1 What is the Asbestos Hazard? It is readily accepted that asbestos, like many other foreign bodies, can cause disabling lung damage (pul monary fibrosis), commonly referred to as asbestosis. This disease and bronchogenic carcinoma (lung can cer) are the two most common as bestos-related diseases. It is important to note that, based on epidemiological data, these diseases have occurred primarily in workers with high, long term exposures to asbestos dust. It is of further interest that one noted re searcher has reported that neither of these diseases is peculiarly related to or caused solely by the inhalation of asbestos fiber.* Another important con sideration is the relation between cigarette smoking and lung cancer, as reported by Dr. E. C. Hammond and Dr. I. J. SeHkoff.4 In this study, they reported that: "It seems clear, then, that lung cancer is uncommon among asbestos insulation workers who have no history of cigarette smoking and that if the risk is increased, such in crease is not great." A third disease, mesothelioma, has more recently been associated with persons exposed to asbestos. Meso thelioma is an extremely rare oancer of the lining of the chest (pleura) or the abdominal cavity (peritoneum). In contrast to the lung diseases, there is some evidence that mesothelioma can occur after brief exposures to relatively high fiber levels. According to the 33-member Ad visory Committee on Asbestos Can Table 2--Comparative Data for Asbestos Minerals* Formula Chrysotile Crocidolite Amosite Anthophylliti 3Mg02$i0s 2H.O No.OFejO. 1.5Mg0 5.5Fe0 7Mg0 8Si0,H-C 8SiO-'H-0 8SiO,H-0 Composition, % SiOs MgO FeO Fe.O, ALO, CD H.O CaO NasO CaO-|-Na.O CM Crystals Color Texture Flexibility Hardness, mohs Fiber diameter, A Tensile, mpsi Surface charge Resistance to arid Resistance to alkali 37-44 39-44 0--6 0-5 0-2 12-15 0-5 ___ -- Fine fibers Cray green Soft silky Very good 2.5-4 180-300 800 Positive Poor Good 49-53 0-3 13-20 17-20 -- 2-5 ___ 4-8 - Brittle fibersi Blue Harsh Good 4 600-900 600 Negative Good Good 49-53 1-7 54--44 ___ 2-9 2-5 -- 0--3 Prismatic Gray/brown Harsh Good 5.5-6 600-900 200 Negative Good Fair 56--58 28-34 3-12 -- 0-2 1-6 -- -- -- Prismatic Gray Harsh Poor 5.5-6 600-900 <4 Negative Very good Good (a) Sources: Modern Plastics Encyclopedia (1973), and Encyclopedia of Chem. Tech., Vol. 2. cers of the International Agency for Research on Cancer (a division of the World Health Organisation): "There is evidence of an association of mesothelial tumors with air pollution in the neighborhood of crocidolite mines and of factories using mixtures of as bestos fiber types. The evidence re lates to conditions of many years ago. There is evidence of no excess risk of mesotheliomas from asbestos air pollution which has existed in the neighborhood of chrysotile and amosrte mines. There are reported differ ences on incidence of mesothelioma between urban and rural areas, the causes of which have not been estab lished. There is no evidence of a risk to the general public at present."* The same body quoted above has also concluded that there is, at pres ent, no evidence of lung damage by asbestos to the general public; and such evidence as there is does not in dicate any risk of cancer resulting from asbestos fibers present in water, beverages, food, or in the fluids used for the administration of drugs. While there seems to be general agreement that the public is not in any present danger from asbestos, it is also recognized that excessive, long term occupational exposure can cause serious health problems. Also, if man made emissions are not controlled, then environmental contamination could could approach harmful levels. During the past two years, significant legislation has been enacted by the Federal government to reduce and control occupational exposure to as bestos fibers and to minimize fiber emissions to the environment Addi tional standards or regulations have been proposed or enacted 'by many states and local governments. Summary of OSHA Regulations The Willram-Steiger Occupational Safety and Health Act of 1970 be came effective on April 28,1971, with 64 Journal of Paint Technology CTC009358 the following Congressional purpose: Improper interpretation of the reg EPA Standards "To assure so far as possible every ulations has created many miscon working man and woman in the na ceptions about equipment and pro Whereas OSHA is responsible for tion safe and healthful working con cedures needed to properly use the protection of the worker, the En ditions and to preserve our human asbestos. If exposure limits are not vironmental Protection Agency (EPA) resources." The Act established the exceeded, there are no further com is charged with improving the en Occupational Safety and Health Ad pliance requirements except for med vironment to which the general public ministration (OSHA) within the De ical examinations. Medical examina is exposed. On March 31, 1971, as partment of Labor, which has re tions are required for all employees bestos, along with beryllium and sponsibility for administration and in any occupation exposed to airborne mercury, was identified as a "hazard enforcement. Research and related concentrations of asbestos fibers. The ous air pollutant" by the Administra functions are handled by the Depart ment of Health, Education and Wel fare (HEW) through the National Institute of Occupational Safety and Health (NIOSH). Five million em examinations are relatively simple and should cost no more than $50 per year, per employee. Respirators and special clothing tor of the EPA. National Emission Standards for asbestos were then pub lished by EPA in the Federal Regis ter, Vol. 38, No. 66, April 6, 1973. Although no numerical emission stan ployers and 60 million of the nation's are required in the construction trade dards were established, operating cri 80 million workers are covered by for the spray application of insulation teria are prescribed to prevent or OSHA. Specifically excluded from coverage are government employees and fireproofing materials, and for the removal of such materials. This spe limit asbestos emissions to the out side air from asbestos mills, roadways, and operations which are protected under other federal health and safety cial protection is not required for any other use of asbestos unless exposure certain manufacturing operations, building demolition, and the spray-on laws. In a news release issued January l'mits are exceeded. This is also true application of materials used to in 4, 1972, OSHA announced a Target Health Hazards Program aimed at improving health factors associated with working conditions. The follow ing five substances were designated to be the focus of initial and con certed efforts by OSHA and NIOSH: asbestos, cotton dust, silica, lead, and carbon monoxide. for other items such as specially equipped tools, change rooms, clothes laundering, and waste disposal. Res pirators are not a substitute for en gineering controls, but the law allows their use while controls are being implemented, in special situations where controls are not feasible or adequate, in emergencies, and for in frequent short-term, job assignments. sulate or fireproof equipment and machinery. The law further requires that spray-on materials used to in sulate or fireproof buildings, struc tures, pipes, and conduits shall con tain less than 1* asbestos on a dryweight basis. This should significantly reduce emissions to which the gen eral public may be exposed, especially in large urban areas. At the present time, new standards have been established only for asbes Caution labels are required on prod ucts containing asbestos except where ". . . the Administrator (of EPA) has determined that, in order to pro tos, although, of the 8,000 toxic sub the fibers have been modified by a vide an ample margin of safety to stances on the NIOSH list, only 500 bonding agent or other material to protect the public health from as are covered by standards and many prevent dusting during any normal bestos, it is necessary to control emis of those need updating. The new subsequent use or handling. Besides sions from major man-made sources Standard for Exposure to Asbestos raw asbestos fiber, products which of asbestos emissions into the atmos Dust was published in the Federal require package labeling could in phere, but that it is not necessary to Register, Vol. 37, No. 110, on June 7, clude: dry acoustical spray products prohibit all emissions. 1972. The basic exposure standard is and joint cements, unsaturated roof "In this determination, the Admin an 8-hr time weighted average ing felt and textiles, and some in istrator has relied on the National * (TWA) of five fibers, longer than 5 sulating products made without ade Academy of Sciences' report on as ' micrometers, per cubic centimeter of quate binders. The labeling of a prod bestos, which concludes: "Asbestos is f\i air. The TWA limit is to be reduced uct does not prohibit its use. It too important in our technology and to two fibers per cubic centimeter on should be noted here that in at least economy for its essential use to be July 1, 1976. A peak concentration 90S of the products containing as stopped. But, because of the known of 10 fibers per cubic centimeter is bestos. the fibers are solidly locked serious effects of uncontrolled inha not to be exceeded at any time. All into the product thereby presenting lation of asbestos minerals in indus of the fiber concentrations are those little danger of dust generation dur try, and uncertainty as to the shape to which an employee may be ex ing normal use and handling of the and character of the dose-response posed without protective clothing and product.' curve in man, it would be highly im- equipment. The first basic require ment of the new standard is monitor ing to determine whether or not fiber concentrations are in excess of the exposure limits. Some asbestos sup pliers provide a monitoring servioe to JOHN L. MYERS, Marketing Manager for the Calidria Asbestos Group in Union Carbide's Metals Div., received customers, and a similar service may be obtained from state health depart ment officials, insurance carriers, or private consultants. The law requires that monitoring be repeated as nec his B.S. Degree in Chemical Engineering from Purdue University in 1951. Joining Union Carbide that same year, he served in the Nuclear Division until 1966, when he be came a Research Engineer in the asbestos group. He was promoted to his present position in 1970. essary to ensure that employees are not exposed to levels in excess of the exposure limits. CTC009359 Vol. 47, No. 611, December 1975 65 prudent to permit additional con tamination of the public environment with asbestos. Continued use at min imal risk to the public requires that the major sources of man-made as bestos emission into the atmosphere be defined and controlled.' "T What is Industry Doing? The Asbestos Information Associa tion/North America reports that, dur ing the past 30 years, the asbestos in dustry has spent millions of dollars to improve mining, milling, and manufac turing methods.* The establishment of safer working conditions has been a prime target and this work continues unabated and in close association with government agencies and independent medical researchers.* The ultimate goals of the asbestos industry are: Reduction of work-area dust to minimum levels; Protection of workers from asbestos-related dis eases; Maintenance of environmental emissions at levels low enough to pre clude public endangerment. Table 4--Typical Air Sampling Results* Ceiling Type Plont Concentration, Or Operation Asbestos Fibers/cc Floor tile Polyester Phenolic compounding Handling phenolic Caulks and sealants Gypsum compounds 1-3 1-3 2-5 3-14 0-8 2-9 (a) Source: Union Carbide Corp., from air monitoring reports. able OSHA level is 10 fibers/oc. In most cases, the TWA exposure level would be well below OSHA stan dards. Most of the data were collected before the installation of any special dust-control measures. Monitoring of ten shows that obviously dusty con ditions are caused by materials other than asbestos. This does not preclude the need for controls, but it could change their scope and facilitate com Dust-Control Measures Asbestos producers and users are spending a considerable amount of time and money on various dust-con trol measures. Conventional means to achieve minimum dust levels include: filtered ventilation systems on process equipment, local ventilation for saws and similar tools, conversion to a "wetted" operation, leak-proof pack aging, vacuum clean-up, more care in bag disposal and other asbestos waste handling, and automatic bag openers. Unusual innovations include: pel letized asbestos, special packaging, and treated products. Only short-fiber chrysotile is avail able as pellets, but this product serves a fair portion of the asbestos market. Pellets not only reduce dust during conventional handling but they are also available in bulk hopper oars and can be transferred and used in totally enclosed systems. Barring leaks in the system, dust in work areas is virtually eliminated. Used in bulk, asbestos pellets also reduce shipping costs, eliminate warehouse storage and pliance with government regulations. handling, facilitate automation, reduce Air Sampling Because of "bad press," asbestos is clean-up, and eliminate bag handling frequently ordered out of use without and disposal. The pellets contain no In order to comply with OSHA regard to whether or not a hazard binder and are friable enough to be standards and to determine the need actually exists due to air contamina dispersed in dry form or in aqueous for dust control measures, air monitor tion. If acceptable dust levels are or resinous systems with conventional ing should be conducted in areas feasible, there is no need to replace high-shear grinding equipment.1* where asbestos is regularly handled asbestos at the expense of product Several types of special packaging or used. OSHA standards require that quality or economic penalty. Gordon are currently available, and suppliers "all determinations of airborne con Everett of EPA points out that in consider customer requests for unus centrations of asbestos fibers shall be formation on the biological effects of ual requirements. The floor tile indus made by the membrane filter method asbestos is very limited and that the try can obtain asbestos in plastic bags at 400-450X (magnification) (4 milli effects of many substitutes have not which can be added directly to the meter objective) with phase contrast been investigated at all. Before as compounding operation. Asbestos in illumination."10 The equipment for bestos is replaced, it should be cer bleached paper bags assembled with collecting air samples costs less than tain that a safer alternative is avail water-soluble glue and printed with $400 and is readily available. A phase able.1* water-dispersible ink can be added OD contrast microscope can be obtained Obviously there are more people directly to paper-making finishes or for as little as $600, or an existing exposed to products containing asbes acoustical tile formulations. microscope can be modified for tos than there are to raw asbestos Although "wetted" asbestos is not "counting" the asbestos fibers in com fibers. As noted previously, more than generally available, most suppliers pliance with NIOSH criteria.11 CM Air samples have been collected 90% of the asbestos used in this coun try is in products in which the asbes are working with customers to pro vide "dustless" products. When justi and analyzed on a regular basis by tos is "locked in" or bound with ce fied by market demand, asbestos can the asbestos industry for years. Ex ment, plastics, or other binders, so be treated with water, mineral spirits, cept for a few applications where dust that there is no release, or at least no glycol, or other materials compatible control is an engineering problem, in significant release, of fibers in work with the application or system. dustry is finding that dust levels are areas or to the environment. Materials already within acceptable standards or that minimum changes are nec or products with locked-in fibers would include: floor tile, polyester Conclusion essary to achieve compliance. Al resins, phenolics, sealants, coatings, Asbestos is one of industry's many though data on many asbestos/plastic brake linings, friction materials, rub raw materials which involves a po applications are not available, the ber, roofing compounds, and rein tential hazard when not used with summary in Table 4 is typical of our forced plastics. Since an abrading ac reasonable respect and care. Although measurements of dust levels during tion on some of these products could all forms of asbestos are recognized asbestos handling in various types of release asbestos fibers, appropriate as hazardous to health when inhaled plants and operations. The dust levels monitoring and/or control measures excessively, there is growing evidence reported are ceiling concentrations, should be instituted if it is thought that croddolite and amosite are more and it should be noted that the allow that such action would release fibers. hazardous than chrysotile. Fortunate- TC009360 66 o Journal of Paint Technology ]y, the plastics industry uses primarily chrysotile asbestos and, in most prod ucts, the fibers are locked-in to pre vent airborne contamination. Al though asbestos dust levels are gen erally lower than expected, industry continues to expend large amounts of time and money to further improve the quality of the workplace. Al though the general public is not cur rently in danger, occupational controls are required to prevent future en vironmental contamination. Chrysotile asbestos is an important and necessary raw material, vital to the nation's safety and economy; and, with proper control, it can be used safely and in compliance with govern ment regulations. Medical, scientific, government, and industrial personnel must continue to work closely to gether to establish reasonable expo sure limits, provide safe work areas, and eliminate any possibility of public endangerment. References (1) Enterline, P. E. and Henderson, V.. Arch. Environ. Health, 27, 312 (Nov. 1973). (2) Wagner, J. C., Ann. Occup. Hyg., 15, 61 (1972). (3) Wright, G. W., statement before U.S. Dept, of Labor, Occupational Safety and Health hearing on pro posed occupational asbestos stan dard, March 16, 1972, p. 3. (4) Hammond E. C. and Selikoff, I. J., "Relation Of Cigarette Smoking To Risk of Death of Asbestos-Associ ated Disease among Insulation Workers in the U.S.A.," presented at meeting of the Working Group to Assess Biological Effects of As bestos, International Agency for Re search on Cancer. Lyon, France (Oct. 4, 1972). (5) `Report of the Advisory Committee on Asbestos Cancers," Brit. J. In- dustr. Med., 30, 180 (1973) . (6) "Asbestos," National Safety News (Oct. 9, 1973). (7) "National Emission Standards for Hazardous Air Pollutants," Federal Register, 38, No. 66, 8820 (April 6, 1973). (8) "Protecting the Asbestos Worker," Booklet No. 101D37, The Asbestos Information Association/North America, p 5. (9) Selikoff, I. J,, Industr. Medicine, 39, No. 4, 21 (April 1970). (10) "Standard for Exposure to Asbestos Dust," Federal Register, 37, No. 110, 11320 (June 7, 1972). (11) Bayer, S. G., et al, "Equipment and Procedures for Mounting Millipore Filters and Counting Asbestos Fibres by Phase-Contrast Microscopy," Bureau of Occup. Safety and Health, U.S. Dept, of Health, Edu cation, & Welfare (Feb. 1969). (12) "Asbestos Health Question Per plexes Experts," Chem. Eng. News, 18 (Dec. 10, 1973). (13) Myers, J. L., "Calidria Asbestos Pel lets," ASBESTOS (Oct. 1971) . Vol. 47, No. 611, December 1975 D c\f 67 CTC009361 A c. 1O * 'u I CTC009363 r\ 5 \V Reprinted from the December 1975 issue of the JOURNAL OF PAINT TECHNOLOGY Volume 47; Number 611; Pages 63-67 Copyright 1975 by the Federation of Societies for Coatings Technology, Philadelphia, Pennsylvania, U. S. A. CTC009364