Document 0JRvDMrXRN25aOrXgLQavkwYO

Accepted for presentation at Ihe 32nd Annual Technical Conference of the Society of Plastics Engineers May 13-16, 1974 fiat for pobI I caljon, do--wot uap^-er mie.rp4 any por-t-&r> of thic paper CHRYSOTILE ASBESTOS IN PLASTICS John L. Myers "CALIOR1A" ASBESTOS UNION CARBIDE CORPORATION MININS AND METALS DIVISION . NIAGARA FALLS, HEW - YORK * December 20, 1973 INTRODUCTION .' 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 confusion 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 In 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 experience with air sampling and dust control measures are also covered. WHAT IS ASBESTOS? Asbestos is a commerlcal 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 crocidolite, amosite, anthophy11Ite, tremoiite and actinoiite. Chrysotile is by far the most used variety and accounts for over 952 of U.S. consumption, as noted in Table 1. Crocidolite, also known as blue asbestos, is Imported from South Africa. Because of Its high mechanical strength and good resistanco 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 insulation. Although there are some deposits of anthophy11Ite In the U.S., most of it is imported from Finland. It Is used primarily as a filler for polypropylens and in Insulating materials. A comparison of the four varieties of asbestos \*hich are of commercial importance Is presented in Table It. It should be noted that there are significant ~ differences between chrysotile and the amphiboles with regard to chemical composition and certain physical..properties. . WHERE IS ASBESTOS USED AND WHY? Asbestos has served mankind for over 100 years in a broad variety of applications. The general areas in which asbestos is used in the United States are snown in Table III. Based on information from asbestos producers and consumption surveys. It is estimated that the plastics Industr- uses about 1/3 of the 000,000 tons consumed annually, which i.es it the largest singlo user oi asbestos fiber. ' The largest uses of ashes-?--' by the plastics Industry are in vinyl/asbestos floor tile .'.nd in phenolic molding compounds.. It Is also used In other plastics such as polypropylene, polyester, nylon, mcljmine, epoxy, silicones and vinyls. Asbestos provides . t a_va|uable function In such products as brake linings, clutch facings, electrical components, automotive parts, furniture, boats, sealants, coatings, adhesives and mastics. The most Important functions of asbestos in plastics are reinforcement dimensional stability, heat resistance, flow control and general-purpose filling. Most of the functions aro supplied by short fiber chrysotile asbestos fiber, although longer chrysotile - fibers and other asbostos varieties are sometimes required for particular properties. " WHY USE-CHRYSOTILE?. . ' Among the several -advantages of chrysotile, which set it apart from the amphlbole minerals and account for Its widespread and Increasing usage, are world wide availablIity, mechanical strength, flexibility, positive surface charge, low iron content, softness and lav refractive index. It is conservatively estimated that chrysotile asbestos is used In over 3,000 applications and in . most of these applications It Is an essential ingredient for which no replacement Is readily available. ' The Information in Table I shows that'the use of chrysotile * asbestos and its share of the total market are steadily increasing. This is partly due to technical advances permitting the broader use of chrysotile in plastics and the general decline in the use of asbestos in certain fireproofing and insulating materials. In addition, there is increasing evidence that crocidolite and amosite are more hazardous to human health than chrysotile (I). Since 1970 the use of crocidolite in Britain has been restricted after a panel of experts "concluded there was sufficient evidence to suggest other types of fibre should be substituted for crocidolite wherever possible." (2) . WHAT IS THE ASBESTOS HAZARD? - - It is readily accepted that asbestos, like many other foreign bodies, can cause disabling lung damage (pulmonary fibrosis), commonly referred to as asbestos is. This disease and bronchogenic carcinoma (lung cancer) are the two most common asbestos-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 researcher has reported that neither of these diseases is peculiarly related to or caused solely by the Inhalation of asbestos fiber (3). Another important consideration is the relation between cigarette smoking and lung cancer as reported by Dr. E. C. Hammond and Dr. I. J. Selikoff (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 increase is not great." .- A third disease, mesothelioma, has more recently been .associated v/ith persons exposed to ic&estos. Mesothelioma is an extremely . rare cancer of the lining of the chest (pleura) or the abdominal cavity (peritoneum). In contrast to tho lung diseases, there is some evidence that mesothelioma can occur after brief exposures to relatively high fiber levels. . . rW C ID -htM M . 1 According to the 33-membcr Advisory Committee on Asbestos Cancors of the International Agency for Research on Cancer (a division of tho World Health Organization): ... "There is evidence of an association of mesothellal tumours with air pollution in tho neighbourhood of crocidollte mines and of factories using mixtures of asbestos fibre types. .The evidence relates to conditions many yeers ago. There is evidence of no excess risk-of mesotheliomas from asbestos air .pollution which has existed In the neighbourhood of chrysotife andamoslte nines. There are reported differences on incicance "of mesothel icota between urban and rural areas, the causes of which have not been establ ished. There is no evidence of a risk to the general public at present." (5) " The same body quoted above has also concluded that there Is at - present no evidence of lung damage by asbestos to the general public; and such evidence as there is does not Indicate 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 approach harmful levels. During the past two years, significant legislation has been enacted by the Federal Government to reduce and controj occupational exposure to asbestos fibers and to minimize fiber emissions to the environment. Additional standards or regulations have been proposed or enacted by many state and local governments. SUMMARY OF OSHA REGULATIONS The V/i 11 iams-Steiger Occupational Safety and Health Act of 1970 became effective on April 23, 1971, with the following Congressional purpose: "to assure so far as possible every working man and woman in the Nation safe and healthful working conditions and to preserve our human resources." The_ Act established the Occupational Safety and Health Adoinistr3tion (OSHA) within the Department of Labor, which has responsibility for administration and enforcement. Research and related . . functions are handled by the Department of Health, Education and Welfare (HEW) through the National Institute of Occuoational Safety and Health (MIOSH). Five million employers 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 Fedora! health and safety lav/s. In a news release issued January 4, 1972, OSHA announced a Target Health -.jzards Program aimed at improving - health factors associate- --ifh working conditions. The following five substances were designated to be the focus of initial and concerted efforts by OSHA end N'lOSH: Asbestos, Cofton Dust, Silica, Lead and Carbon f-!or-nxide. At the present time new standards hove been establ ishod only ' for asbestos; although, of the 8,090 toxic substances on the MIOfiH list, only 500 ore covered by standards and many of Ihesc need updating. The new Standard lor Exposure to Asbestos Dust was published In the Federal Register, Volumo 37, I Jo. 110 n Wednesday, June 7, 1972. The basic exposure standard is an -hour time-weighted average (TWA) of 5 fibers, longer than 5 Icrometers, per cubic centimeter of air. The TWA limit is o be reduced to 2 fibers per cubic centimeter on July I, 1976. peak concentration of 10 fibers per cubic centimeter is not o be exceeded at any time. All of the fiber concentrations arc those, to which an employee may be exposed without protective clothing or equipment. The first basic requirement of the new_ standard is.monitoring to determine whether or not fiber concentrations are in excess of the exposure I imlts. Some asbestos suppliers provide a monitoring service to customers and a similar service may be obtained from state health department officials, insurance carriers, or private consultants. The law requires that monitoring be repeated as necessary to ensure that employees are not exposed to levels In excess of the exposure limits. Improper interpretation of the regulations has created many misconceptions about the equipment and procedures needed to properly use asbestos. If exposure limits are not exceeded, there are no further compliance requirements except for medical examinations. Medical examinations 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 $50 per year, per employee. Respirators and special'clothing are required In the construction trade for the spray application of insulation and fireproofing materials, and for the removal of such materials. This special protection Is not required for any other .use of asbestos-unless .exposure limits are exceeded. This is also true for other items such as specially-equipped tools,'change rooms, clothes laundering and waste disposal. Respirators are not a substitute for engineering controls'but the law allows their use while controls are being Implemented, in special situations where controls are not feasible or adequate. In emergencies, and for infrequent short-term job assignments. Caution labels are required on products containing asbestos except where the fibers have been modified by a bonding agent or other material to prevent dusting- during any normal subsequent u$e or handling. Besides raw asbestos fiber, products which requiro package - labeling could include: dry acoustical spray products and joint cements, unsaturated roofing felt and textiles, and some insulating products made without adequate binders. The labeling of a product does not prohibit its use. It should be noted here that in at least 90JS of the products containing asbestos, the fibers are solidly locked into the product thereby presenting little danger rf dust generation during normal use and handling of the produ. . - EPA STANDARDS Whereas 0SHA is responsive for the protection of the worker, the Environmental Protect ion Agency (EPA) is charged-with improving tho environment to which the general public is PLAINTIFF'S EXHIBIT HAttCO')- exposed. On March 31, 1971, asbostos, along with borylllum and mercery, was Identified as a "hazardous air pollutant" by the Administrator of the EPA. National Emission Standards for asbestos were then published by the EPA in the Federal Register, Vol. 30, No. 65 - Friday, April 6, 1973. Although no numerical emission standards were established, operating criteria are prescribed to prevent or limit asbestos emissions to the outside air from asbestos mills, roadways, certain manufacturing operations, building demolition, and the spray-on application of materials used to Insulate or fireproof equipment and machinery, he law further requiresthat spray-on materials used to -- insulate or fireproof buildings, structures, pipes, and conduits shall contain less than \% asbestos on a dry weight basis. This should significantly reduce emissions to which the general public may be exposed, especially in large urban areas. "...the Administrator (of the EPA) has determined that. In order to provide an ample margin of safety to protect the public ' health from asbestos. It Is necessary to control emissions from major man-made sources of asbestos emissions into the atmosphere, but that It is not necessary to prohibit all emissions. . In this determination, the Administrator has relied*on the National Academy of Sciences' report on asbestos, which concludes: 'Asbestos is too important in our technology and economy for Its essential use to be stopped. But, because of the known serious effects of uncontrolled inhalation of * asbestos minerals in industry and uncertainty as to the shape and character of the dose-response-curve in man. It would be ' highly imprudent to permit additional contamination of the public environment with asbestos. Continued use at minimal risk ' to the public requires th3t the major sources of man-made asbestos emission into the atmosphere be defined and controlled."'. (7) WHAT IS INDUSTRY DOING? . ' `` The Asbestos Information Association/North America reports that, . during the past 30 years, the asbestos Industry has spent millions of dollars to improve mining, milling, and manufacturing methods (3). 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 (9). The ultimate goals of the asbestos industry are: . . ----- Reduction of work-area dust to minimum levels. --: Protection of workers from asbestos-related diseases. --: Maintenance of environmental emissions at levels low enough to preclude public endangerment. ' AIR SAMPLING In order to comply with c; Standards and to determine the need for dust control measures, air monitoring should be conducted in areas where asbestos is regularly handled or.used. 05MA Standards require that "at < determinations of airborne concentrations of asbestos fibers shall be made by the membrane filter mol hod at 400-450X (magnification) (4 mi 111 mater objective) with ph.ose contrast illumination." (10) The equipment for collecting sir samples cosfs leas than S400 and is readily available. A phase . 1n contrast microscope can be obtained for as little as $600 or an existing microscope can be modified for "counting" the asbestos fibers In compliance with NIOSH criteria (1IJ. Air samples have been collected and analyzed on a regular basis by the asbestos Industry for years. Except for a few applications tfhere dust control Is an engineering problem. Industry is finding that dust levels are already within acceptable standards.or that minimum changes are necessary to-achieve compliance. Although data on many asbestos/plastics applications are not available, the summary In Table IV 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 allowable OSHA'level Is 10 flbers/cc. In most . cases, the TWA exposure level would be well below OSHA Standards. Most of the data were collected before the Installation of any special dust control measures. Monitoring often shows that obviously dusty conditions are caused by materials other than asbestos. This does not preclude the need for controls but It could change their scope and facilitate compliance 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 contamination. If acceptable dust levels are feasible, there is no need to replace asbestos at the expense of product quality or economic penalty. Mr. Gordon Everett of EPA points out that information on the biological effects of asbestos is very limited and that the effects of many substitutes have not been investigated at ail. Before asbestos is replaced, it should be certain that a safer alternative is available (12). Obviously there are more.people exposed to products containing asbestos than there are to raw asbestos fibers. As noted ' previously, over 90% of the asbestos used in this country is in products in which the asbestos is "locked In" or bound with cement, 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-ln fibers would Include: floor tile, polyester resins, phenolics, sealants, coatings, brake linings, friction materials, rubber, roofing compounds and reinforced plastics. Since an abrading action 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 control measures. Conventional means to achieve minimum levels include: filtered ventilation systems on process equir* local ventilation for saws and ' similar tools, conversion to a "wetted" operation, leak-proof packaging, vacuum clean-uo. more care in bag disposal and other asbestos waste handling, an: automatic bag openers. Unusual innovations include: peller>zcd asbestos, special packaging, and treated products. '. Only short-fiber chrysotlle Is available as pollets, but this product serves a fair portion of the asbestos narkot. Pollols not only reduce dust during conventionnI handling but they ore also available in bulk hopper cars and can be transferred and used in totally enclosed systems.- Barring leaks in the system, dust in work areas is virtually eliminated. Used in I* PlAINTJF bulk, asbestos pellets also reduce shipping costs, eliminate If EXHIBI ,warehouse storage and handling, facilitate automation, reduce If /&V/C. clean-up, end eliminate bag handling and disposal. The pel let* | contain no binder-and- are. frlablo enough to be dispersed in dnwHM* . form or In aqueous or resinous systems with conventional high- shear grinding equipment (13).' . - Several types of-speclaI-packaging are.currently available end suppliers consider customer requests for unusual requirements. The floor tile industry 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 furnishes or acoustical celling tile formulations. Water-proof bags are available to permit slurrying of the asbestos In the bag. Wider use of shrink-filming is being offered to reduce dust during bag handling, transportation and storage. Although "wetted" asbestos is not generally available, most suppliers are tforking with customers to provide "dustless" products. When justified by market demand, asbestos can be treated with water, mineral spirits, glycol or other materials compatible with the.appiication or system. ' CONCLUSION r Asbestos is one of industry's many rev/ materials which Involves a potential hazard when not used with reasonable respect and care. Although ell forms of asbestos'are recognized as hazardous to health when inhaled excessively, there Is growing evidence . that crocidollte and amosite are more hazardous than chrysotile. Fortunately the plastics Industry uses primarily chrysotile asbestos . and In most products the fibers are locked-in to prevent airborne contamination. Although asbestos dust levels are generally lower than expected. Industry continues to expend large amounts of time and money to further Improve the quality of the workplace. Although the general public Is not currently In danger, occupational * controls are required to prevent future environmental 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 government regulations. Medical, scientific, government, and industrial personnel must continue to work closely together to establish reasonable exposure limits, provide safe work areas, and eliminate any possibility of public ?ndangcrment. . . REFERENCES: 1. Enterline, P. E. and V. Henderson, "Type of Asbestos and ... -- Respiratory Cancer In.the Asbestos Industry," Arch. Environ. .. Health/Vol. 27, pp. 312-317 (Nov. 1973). - . I* PLAINTIFF'S 2. Wagner, J. C., "Current Opinions On The Asbestos Cancer I f EXHIBIT Problem," Ann. Occup. Hyg., Vol. 15, pp. 61-64 <1972). | __ . I3 * 3. Wright, G. W., Statement before U.S. Dept, of Labor, Occupational Safety and Health Hearing on Proposed Occupational Asbestos Standard, p. 3 (March 16, 1972). * 4. Hammond, E. C. and I. J. Selikoff, "Relation Of Cigarette Smoking To Risk of Death Of Asbestos - Associated Disease Among Insulation Workers in The United States," presented at the meeting of the Working Group to Assess Biological Effects of Asbestos, International Agency for* Research on Cancer, Lyon, France (October 4, 1972). * 5. "Report of The Advisory Committee on Asbestos Cancers," Brit. J. Industr. Med., Vol. 30, pp.I80-I86 (1973). * ' 6 "Asbestos," National Safety News(October 9, 1973). 7 "National Emission Standards for Hazardous Air Pollutants," Federal Register, Vol. 38, No.. 66, p. 6820 (April 6, 1973). ' 8' "Protecting The Asbestos Worker," Booklet.No. I0ID37, p. 5, The Asbestos Information Association/North America. 9. Selikoff, I. J., "Partnership For Prevention," Industrial Medicine, Vol. 39, No. 4, pp. 21-25 (April 1970). * 10. "Standard For Exposure To Asbestos Dust," Federal Register, Vol. 37, No. 110, p. 11320 (June 7, 1972). ' .. * 11. Bayer, S. G. et al, "Equipment end Procedures For Mounting Milljpore Filters and Counting Asbestos Fibres By Phase Contrast Microscopy," Bureau of Occupational Safety and - Health, U.S. Dept, of Health, Education, and Welfare, .(February 1969),. ` ' ' 12. "Asbestos Health Question Perplexes Experts," Chemical and Engineering News, pp. 18-19 (December 10, 1973) * 13. Myers, J. L., "Calldrla Asbestos Pellets," ASBESTOS (October 1971) *  table I APPARE.VT U.s: CONSUMPTION OF ASBESTOS. TONS' (* of Total Shown In Parentheses) Year 196? 1968 1969 1970 1971 1972 Total 720583 817363 784321 J28I3I 758571 808554 Chrvsotl le Aroslte CroeldolIte 686044(95) 1 12358(1.7) 14917(2.1) 775711(95) 20467(2.5) 13965(1.7) 749708(96) 14618(1.9) 10558(1.3) 695770(96) 14261(2.0) ' 8936(1.2) 729272(96) 14580(1.9) 6953(0.9) 791020(98) 7125(0.9) 5374(0.7) Information based on Import and production data from United States Bureau of Hines Minerals Yearbooks. PLAINTIFF'S EXHIBIT TABLE It . COMPARATIVE DATA FOR ASBESTOS MINERALS FORMULA CHRYSOTILE 3Mg0'2St02'2H^) CROCIOOLITE . AMOSITE NajO* ^*2S* 7FeO* 8S I02*H20 I.5MgO*5.5FeO* OSIOrH^O AWTWOPHTLLfTE 7Hg0*8SI02*H20 COMPOSITION,* SI02 KgO FeO Fe^O3 AI203 H2O CaO NajO CeOtUapO CRYSTALS COLOR TEXTURE flexibility hA.-J.VESS, Mohs FIBER 0IA,, A TENSILE, Mosi SURrACE DC. RES. TO ACID RES. TO ALK. 37-44 39-44 0-6 0-5 0-2 12-15 0-5 - Fine Fibers Cray/Green Soft/S 1 Iky Very Good . 2.5-a 180-300 BOO Positive Poor , Good 49-53 0-3 13-20 : 17-20 *2-5 4-8 * Brittle Fibers Blue Harsh Good 4 600-900 600 Negative . Good ' Good 49-53 1-7 34-44 ee 2-9 2-5 .- 0-3 ^ Prismatic Crystals Cray/Brown Harsh - Good 5.5-6 600-900 200 Negative Good Felr . -56-58 . 28-34 - 3-12 ** -- 0-2 1-6 . - Prismatic Crystals * Gray ' Harsh Poor 5.5-6 600-933 <4 Negative Very Good Good Source: Modern Plastics Encyclopedia! 1972-3), and Encyclopedia of Chemical Technology, Volume 2, p. 136(1948).  TABLE III APPARENT U.S. CONSULT I ON OF ASBESTOS BY GENERAL USE AREAS . Area of Use . t of ConsumetIon* Construction ... *40 . Floor Tile Felt and Paper .. . 15' 15 . Friction & Packing 14 Insulation 3 Textiles 2 Other . II *Author's Interpretation of data from the USBM Minerals Yearbook - Asbestos-1972, the Asbestos Information Association/ North America, and personal communi cat ions with Mr. R. A. Clifton of the USBM. TABLE IV TYPICAL AtR SAMPLING RESULTS Type Plant or Operation Floor Tile Polyester Phenolic Compounding Handling Phenolic Caulks and Sealants Gypsum Compounds ' Cel 11ng Concentration, Asbestos FIbers/cc * 1-3 1-3 2-5 3-14 0-8 2-9 Source: Union Carbide Corporation, from air monitoring reports.