Document 9J5461oXRdzJ1q7ZYmrmzBopL

JOURNAL OF PAINT 0 TECHNOLOGY Handling Asbestos Chrysotile Asbestos in Plastics John L. Myers Union Carbide Corporation' AhAtn has ragaivwH 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 poilutanr by the EPA. Many of the articles on asbestos by the press have been emotionally oriented or* distorted and. in some cases, stories have oeen 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. t KEY WORDS: Asbestos: Plastics: Air pollution; Toxicology. What is Asbestos? Asbestos is a commercial or generic term used to describe six naturally occurring "asbestifonn" minerals that are fibrous, hydrated metal silicates. The six varieties are divided into two classes--serpentine and amphibolebased on their crystal structure. Chrysotile is the only member of the serpentine class, while the amphiboles include croddolite, amosite, anth> phyllite, tremoiite, and actteotit*. Chrysotile is by far the most-used variety and accounts for over 9SS of U.S. consumption, as noted in Table 1. CrocidoHie, 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 fiiMwml m ikt fuMH teinr'i Mm. amm SrmaMr krtd in Su Fnactaca, CjiiC.. jam it. I97S. * Metal* Oi* NUcara FaU*. M.Y. UMS, VOL. 47. No. 611, Deczmsex 1975 insulation. Although there are some deposits of anthophyllitc 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 com mercial importance is presented in TaBle 2. It should he noted that there are significant differences between chrysotile and ampliiboles with regard to chemical composition and certain physical properties. Where is Asbestos Used and Why? Asbestos has served mankind for more than 100 yean in a broad vari ety of applications. The general areas in which asbestos is used in the U.S. are shown in Talile 3. Based on infor mation from asbestos producers and consumption surveys, it is estimated that the plastics industry uses shout 33S of the 800,000 tons consumed an nually, which makes it the largest uncle user of asbestos fiber. The largest uses of ashesms by thu 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* Sow control, and gen eral-purpose filling. Most of the func tions are supplied by short-fiber chrysotile asbestos fiber, although longer chrysotile fillers 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 amphibolc minerals ami account for its widespread and increasing us age. are world-wide availability, me chanical strength, flexibility, positive surface cixarge, low iron content, sott* 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 nf 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 crocidoiito and amosite are more hazardous to the following Congressional purpose: "To assure so far as possible every working nun and woman in the na tion safe and healthful working con ditions ami to preserve our human resources." The Act established the Occupational Safety and Health Ad ministration (OSHA) within the De partment of Labor, which has responsilrility for administration and enforcement. Research and related functions are handled hy 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 arc covered by OSHA. Specifically excluded from coverage are government employees and operations which arc 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 working conditions. The follow ing five substances were designated to be the focus of initial and con certed efforts hy OSHA and NIOSH: asbestos, cotton dust, silica, lead, and carbon monoxide. I 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, Vo). 37, No. 110, on June 7, 1972. The basic exposure standard is an 8-hr lime weighted average (TWA) of five fibers, longer than 5 micrometers, per cubic centimeter of air. The TWA limit is to be reduced to twn filters per cubic centimeter on July 1. 1978. A peak concentration of 10 filters per cubic centimeter is not to he exceeded at any time. All of the fiber concentrations are those to which an employee may he ex posed without protective clothing and equipment. 'Hie 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 repented as nec essary to ensure that employees arc not exposed to levels in excess of the exposure limits. Improper interpretation of the reg ulations lias iYe:iit'(! many tniscou- evptumx almut equipment ami promlures needed to properly use adiestos. If exposure limit's arc not rxtvetled. then* are no further com pliance requirements except for med ical examinations. Medical examina tions arc required for all employees in any occupation exposed to airborne concentrations of asbestos filvrx. The examinations arc 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 spe cial protection is not required for any other use of a-slx'stos unless exposure. 1'mits are exceeded. Tin's is also true for njhcr items such as specially equipped tools, change rooms, clothes laundering, and waste disposal. Res pirators are not a suiwtitute for en gineering controls, hut the law allows their use while controls arc being implemented, in special situations where controls arc not feasible or adequate, in emergencies, and for in frequent short-term, {oh assignments. Caution lai)cb arc required on prod ucts containing asbestos except where the fibers have len modified hy a bonding agent or other material to prevent dusting during any normal suisequent use or handling. Besides raw asbestos filler, products which require package labeling could indude: dry acoustical spray products and foint cements, unsaturated roof ing felt and textiles, and some in sulating products made without ade quate binders. The labeling of a prod uct does not prohibit its use. It should lie noted here that in at least 90S of the products containing asliestos. the fibers arc solidly locked into the product thereby presenting little danger of dust generation dur ing normal use and handling of the product.* EPA Standards WIkwis OSllA is responsible for rlu* protection i>f the worker, the En vironmental Protection Agency (EPA) is charged with improving the en vironment to winch the general public is exposed. On March 31. 1971, asliestos, 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. Although no numerical emission stan dards were established, operating cri teria are prescribed to prevent or limit asbestos emissions to die out side air from asbestos mills, roadways, certain manufacturing operations, building demolition, and the spray-on application of materials used to insolute 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 IS asbestos on a dryweight basis. This should significantly reduce emissions to which the gen eral public may l>e exposed, especially in large urban areas. . . the Administrator (of EPA) has determined that, in order to pro vide an ample margin of safety to protect the public health from asiicsros. it is necessary to control emis sions from major man-made sources of asbestos emissions into the atmos phere. but that it is not necessary to prohibit all emissions. "In this determination, the Admin istrator has relied on the National Academy of Sciences* report on as bestos. which concludes: "Asbestos is too important in our technology and economy for its essential use to bo stopped. Rut. l>ecause of the known serious effects of uncontrolled inha lation of asliestos minerals in indus try. and uncertainty as in the shape and character of the cK.e-rospon.se curve in man, it would Ik highly im- JOHN L. MYERS. Marketing Manager for the Calidria Asbestos Group m Union Carbide's Metals Oiv., 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 esbestos group. He was promoted to his present position in 1970. Vol. 47, No. 611, Dcczmsc* 1975 01-Q20557 ly, the plastics industry uses priumrily chrysolite aiHx'Stos .mil. in most prod ucts, the fibers arc !x*ked*in to pre vent airlxime ount.iminntton. Al though asbestos dust levels arc 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 die general public is not cur rently in danger, occupational controls arc required to prevent future en vironmental contamination. Chrysorilc 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 tov establish reasonable expo sure limits, provide safe work areas, and eliminate any possibility of public endangerment Q References (I) Enterline. P. E. and Henderson. V.. Arch, Envimn. [itaUh, 27, J12 (Nov. 1975). (V) Wagner. J. C- Ann. Oeeup. Hyg., 15. 61 (1972). (5) Wright. O. \V.. statement before VS. Dept, of Lal>or. Occupational Safety and Health hearing on pro posed occupational asbestos stan dard. March 16. 1972. p. S. (4) Hammond E. C and Sdikoff. I. J.. "Relation Of Cigarette Smoking To Risk of Death of Ashestcs-Asand- atcil Disease among Insulation Workers in the U-S.A" presented at meeting of tlte Working Croup to Assess 2Uological Effects of As- betios. International Agency for Re- search on Cancer. Lyon. Franc* (Oet. 4.1972). (5) 'Report of the Advisory Committee on Asbestos Cancers.** Brit. J. In- dustr. Med.. SO. 180 (1975). (g) "Asbestos." X*tion*i Safety Sews (Oet. 9. 1973). . (7) "National Emasion Standards for Haaardous Air Pnilutanu," Federtl Register, it. No. G6. 8820 (April 6. 1973). (8) "Protecting the Asbestos Worker." Booklet No. 101DS7. The Asbestos Information Assodation/North . Amerio. p & (9) Sdikoff. I. j.. lr>dustr. Medicine, if. No. 4. 21 (April 1970). (10) "Standard for Exposure to Asbestos Dust.** Federal Register, 37, No. 110, 11320 Mune 7. 1972). (II) Bayer, a. G~ et al. "Equipment and Procedures for Mounting MilUpore Filters and Counting Asbestos Fibres by Phase-Contrast Microscopy." Bureau of Occup. Safety and Health. U-S. Dept, of Ucaith. Edu cation. It Welfare (Feb. I960). (12) "Ashcuo* Health Question Per plexes Experts." Chem. Eng. News, 18 (Dee. 10, 1973). (IS) Myers. I. L~ "Cslidria Asbestos Pel- lets," ASBESTOS (Oet. 1071). Vou 47, No. 611, December 1975 Asbestos Information Association North America 1660 L Street. N. W. Washington, D. C. 20036 -