Document 6wznBYJMkz2DRG3X9eJM7ZJLg

i- Chrysotile Asbestos in Plastics John L. Myers Union Carbide Corporation* Asbestos has received a great deal of attention and publicity in recent years, floor tile and in phenolic molding especially after it was designated a "target health hazard" by OSHA and a compounds. It is also used in other "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. 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, fumitore, boats, sealants, coatings, adhe sives and mastics. The most important functions of asbestos in plastics are re inforcement, dimensional stability, KEY WORDS: Asbestos; Plastics; Air pollution; Toxicology. heat resistance, flow control, and gen eral-purpose filling. Most of the func tions are supplied by short-fiber chrysotile asbestos fiber, although What is Asbestos? insulation. Although there are some longer chrysotile fibers and other as bestos varieties are sometimes re Asbestos is a commercial or generic term used, to describe six naturally . occurring "asbestifoim" 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 crocidolite, amosite, anthophyllite, tremolite, and actinolite. Chrysotile is by. far the most-used 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 erf asbestos which are of com mercial 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. quired for particular properties. Why Use Chrysotile? Among the several advantages of chrysotile,, which set it apart from....... . the amphibole minerals and aocount 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 variety and accounts for over 95 of U.S. consumption, as noted in Table 1. . / Where is Asbestos Used and Why? tile asbestos is used in over 3,000 ap plications and, in most of these appli cations, it is an essential ingredient Crocidolite, also known as blue as Asbestos has served mankind for for which no replacement is readily bestos, is imported from South Africa. more than 100 years in a broad vari available. Because of its high mechanical ety of applications. The general areas The information in Table 1 shows strength and good resistance to acids in which asbestos is used in the U.S. that the use of chrysotile asbestos and and alkalis, it is used to reinforce a are shown in Table 3. Based oh infor its share of the total market are stead s limited variety of plastics where its pronounced color is not objectionable. mation from asbestos producers and consumption surveys, it is estimated ily increasing. This is due partly to technical advances permitting file Amosite, also imported from South that the plastics industry uses about broader use of chrysotile in plastics Africa, is used primarily in thermal 33 of the 800,000 tons consumed an and the general decline in the use of f- nually, which makes it the largest asbestos in certain fireproofing and in Presented, at the Golden Gate Society's Man single user erf asbestos .fiber.. . sulating materials. In addition, there agement Seminar held in Sin Francisco, Calif., The largest uses of asbestos by the is increasing evidence that crocidolite * i June IS, 1975. * Metals Div., Niagara Falls, X.Y. 14302. plastics industry are in vinyl-asbestos and amosite are more hazardous to * Vol. 47, No. 611, December 1975 63 UCC 004996 Year 1967 1968 1969 1970 1971 1972 Table T--Apparent U.S. Consumption of Asbestos, Tons* Total Chrysottle Amosite Crocidolite 720.588 817,363 784,321 728,131 758,571 808,554 686,044 (95) b 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) 14^61 (2.0) 14,580(1.9) 7.125(0.9) 14,917 (2.1) 13,965(1.7) 10,553 (1.3) 8,936(1.2) 6,953 (0.9) 5.374 (0.7) (a) Information based on import and production data fw>m U. S. Bureau of Mines* Minerals Yearbooks, fb) 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 n human health than cbrysotile,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."* What is the Asbestos Hazard? If 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 dear, 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 cancer 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-memfeer Ad visory Committee on Asbestos Can- Tabte 2--Comparative Data for Asbestos Minerals* Formula Chrysotile Crocidolite Amosite Anthophyllite 3Mg02Si0, 2H=0 Na-OFe-Oj1 1.5Mg0 5.5Fe0 7Msa8$iO! H-O 8$iO*'H-0 SSiOaH-O Composition, % SiO= MgO FeO Fe,0, Al-O,. HsO CaO Na..O CaO-|-Na30 C ratals Color Texture Flexibility Hardness, mohs Fiber diameter, A Tensile, mpsi . Surface charge Resistance to add Resistance to alkali 37-44 39--44 0--6 0--5 0-2 12--15 0--5 ___ -- Fine fibers Gray 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 fibersBine Harsh Good 4 600-900 600 Negative Good Good 49-53 1--7 34--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 0975), and Encyclopedia of Chem- Tech., Voh 2. cere of die International Agency for Research on Cancer (a division of the World Health Organization): "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 die neighborhood of chrysotile and amosite 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 asb&tos 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. Abo, if man made emissions are not controlled, then environmental contamination aM could approach harmful levels. During the past two years, significant' legislation has been enacted by dr Federal government to reduce a* control occupational exposure to bestos fibers and to minimize emissions to the environment, tional standards or regulatior been proposed or enacted V states and local government? Summary of OSHA P The WiHiam-Steige Safety and Health / came effective on Ay 64 Journal of Pain UCC 004997 the following Congressional purpose: "To assure so far as possible every working man and woman in the na tion safe and healthful working con ditions and to preserve our human resources," The Act established the Occupational Safety and Health Ad ministration (OSHA) within the De partment of Labor, which has re sponsibility for administration and enforcement. Research and related 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 ployers and 60 million of the nation's 80 million workers are covered by OSHA. Specifically excluded from coverage are government employees and operations which are protected under other federal health and safety laws. In a news release issued January 4, 1972, OSHA announced a Target Health Hazards Program aimed at improving health factors associated with worlang 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. At the present time, new standards have been established only for asbes tos, although, of the 8,000 toxic sub stances on the NIOSH list, only 500 are covered by standards and many of those need updating. The new Standard for Exposure to Asbestos Dust was published in the Federal Register, Vol. 37, No. 110, on June 7, 1972. The basic exposure standard is an 8-hr time weighted average (TWA) of five fibers, longer than 5 micrometers, per cubic centimeter of air. The TWA limit is to be reduced to two fibers per cubic centimeter on July 1, 1976. A peak concentration of 10 fibers per cubic centimeter is not to be exceeded at any time. All of the fiber concentrations are those to which an employee may be ex posed without protective clothing and 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 service to 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 essary to ensure that employees are not exposed to levels in excess of the . exposure limits. Improper interpretation of the reg EPA Standards ulations has created many miscon ceptions about equipment and pro cedures needed ,, to properly use asbestos. If exposure limits are not exceeded, there are no further com pliance requirements except for med ical examinations. Medical examina tions are required for all employees in any occupation exposed to airborne concentrations of asbestos fibers. The examinations are relatively simple and should cost no more than $50 per year, per employee. Whereas OSHA is responsible few the protection of the worker, the En vironmental Protection Agency (EPA) is charged with improving the en vironment to which the general public is exposed. On March 31, 1971, as bestos, along with beryllium and mercury, was identified as a "hazard ous air pollutant" by the Administra 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. Respirators and special clothing Although no numerical emission stan are required in the construction trade dards were established, operating cri for the spray application of insulation teria are prescribed to prevent or and fireproofing materials, and for the limit asbestos emissions to the out removal of such materials. This spe side air from asbestos mills, roadways, cial protection is not required for any certain manufacturing operations, other use of asbestos unless exposure building demolition, and die spray-on limits are exceeded. This is also true application of materials used to in for ether items such as specially sulate or fireproof equipment and equipped tools, change rooms, clothes machinery. The law further 'requires laundering, and waste disposal, Res that spray-on materials used to in pirators are not a substitute for en sulate Or fireproof buildings, struc gineering controls, but the law allows tures, pipes, and conduits shall con their use while controls are being tain less than \% asbestos on a dry- implemented, in special situations weight basis. This should significantly where controls are not feasible or reduce emissions to which the gen adequate, in emergencies, and for in eral public may be exposed, especially frequent short-term, job assignments. in large urban areas. Caution labels are required on prod ". . . the Administrator (of EPA) ucts containing asbestos except where has determined that, m order to pro the fibers have been modified by a vide an ample margin of safety to bonding agent or other material to protect the public health from as prevent dusting during any normal bestos, it is necessary to control emis subsequent use or handling. Besides, sions from major man-made sources raw asbestos fiber, products which of asbestos emissions into the atmos require package labeling could in phere, but that it is not necessary to clude: dry acoustical spray products .. prohibit all emissions. . and joint cements, unsaturated roof "In this determination, the Admin ing felt and textiles, and some in istrator has relied on the National sulating products made without ade Academy of Sciences' report on as quate binders. The labeling of a prod bestos, which concludes: "Asbestos is uct does not prohibit its use. It too important in our technology and should be noted here that in at least economy for its essential use to be 90S of the products containing as stopped. But, because of the known bestos. the fibers are solidly locked serious effects off uncontrolled inha into the product thereby presenting lation of asbestos minerals in indus little danger of dust generation dur try. and uncertainty as to the shape ing normal use and handling of the and character of the dose-response product.' curve in man, it would be highly im- JOHN L. MYERS, Marketing Manager for the Calidria Asbestos Group in Union Carbide's Metals Div., received 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. Vol. 47, No. 611, December 1975 65 UCC 004998 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.' 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. Air Sampling In order to comply with OSHA standards and to determine the need for dust control measures, air monitor ing should be conducted in areas where asbestos is regularly handled or used. OSHA standards require that "all determinations of airborne con centrations of asbestos fibers shall be made by the membrane filter method at 400-450X (magnification) (4 milli meter objective) with phase contrast illumination."1" The equipment for collecting air samples costs less than S400 and is readily available. A phase contrast microscope can be obtained for as little as $600, or an existing microscope can be modified for "counting" the asbestos fibers in com pliance with NIOSH criteria.11 Air samples have been collected and analyzed on a regular basis by the asbestos industry for years. Ex cept for a few applications where dust control is an engineering problem, in dustry is finding that dust levels are already within acceptable standards or that minimum changes are nec essary to achieve compliance. Al though data on many asbestos/plastic applications are not available, the summary in Table 4 is typical of our measurements of dust levels during asbestos handling in various types of plants and operations. The dust levels reported are ceiling concentrations, and it should be noted that the allow Table 4--Typical Air Sampling Results* Ceiling Type Pfant Concentration, Or Operation Asbestos Fibrs/ce 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 pliance with government regulations. Because of "bad press," asbestos is frequently ordered out of use without regard to whether or not a hazard actually exists due to air contamina tion. If acceptable dust levels are feasible; there is no need to replace asbestos at the expense of product quality or economic penalty. Gordon Everett of EPA points out that in formation on the biological effects of asbestos is very limited and that the effects of many substitutes have not been investigated at all. Before as bestos is replaced, it should he cer tain that a safer alternative is avail able.1' Obviously there are more people exposed to products containing asbes tos than there are to raw asbestos fibers. As noted previously, more than 90S of the asbestos used in this coun try is in products in which the asbes tos is "locked in" or bound with ce ment, plastics, or other binders, so that there is no release, or at least no significant release, of fibers in work areas or to the environment. Materials or products with locked-in fibers would include: floor tile, polyester resins, phenolics, sealants, coatings, brake linings, friction materials, rub ber, roofing compounds, and rein forced plastics. Since an abrading ac tion on some of these products could release asbestos fibers, appropriate monitoring and/or control measures should be instituted if it is thought that such action would release fibers. 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 v 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 - handling, facilitate automation, reduce clean-up, and eliminate bag handling and disposal. The pellets contain no binder and are friable enough to be dispersed in dry form or in aqueous or resinous systems with conventional high-shear grinding equipment.1* Several types of special packaging are currently available, and suppliers consider customer requests for unus ual requirements. The floor tile indus try can obtain asbestos in plastic bags which can be added directly to the - compounding operation. Asbestos in bleached paper bags assembled with water-soluble glue and printed with water-dispersible ink can be added directly to paper-making finishes ot acoustical tile formulations. "v`"* Although "wetted" asbestos is not generally available, most suppliers are working with customers to pro-/ vide "dustless" products. When fied by market demand, asbestos can be treated with water, mineral spirits,: glycol, or other materials compatible with the application or system. Conclusion - Asbestos is one of industry's many , raw materials which involves a po tential hazard when not used with reasonable respect and care. Although all forms of asbestos are recognized as hazardous to health when inhaled excessively, there is growing evidence that croddolite and amosite ate more hazardous than chrysotile. Fortunate- 66 Journal of Paint Techno UCC 004999 - ]y, the plastics industry uses primarily ehrysotile 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, wi th 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. Q] References (1) Enterline, P. E. and Henderson, V., Arch. Environ. Health, 27, 312 (Nov. 1973). (2) Wagner, J. C,, Ann. Occup. Hyg., 17, 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 L6, 1972, p. 3, (4) Hammond E. C. and Selikolf, 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, ISO (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 It could be your competitive edge for tomorrow. In the production of any aikyd resin, Technical Rentaerythritol has a combi nation of advantages not found in com petitive polyols. This includes higher resin viscosities and shorter cooking time. Color stability, gloss retention, water resistance and drying time are all excellent. Low-cost resins frequently are made by combining Technical Pentaeryihritol with ethylene glycol or with propylene glycol; superior short and medium oil alkyds are made by com bining it with TRIMET (brand of pentaglycerol). 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