Document dnY7pmDGMbLrY12L41m38V0M5

AIA-60 JOURNAL OF PAINT TECHNOLOGY Handling Asbestos Chrysotile Asbestos in Plastics John L. Myers Union Carbide Corporation** t 7 h rprnivwrt a great deal of attention and publicity m recent years, especially after it was designated a "target health hazard" by OSHA and a "hazardous air pollutant" by the ERA. 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 ano asbestos hazards into a logical and practical perspective. In this paper, the different types of asbestos and their many uses are discussed, along witn 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 s 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 amphibolebased on their crystal structure. Chrysotile is the only member of the serpentine class, while the amphiboles include croddolite, amosite, anthophyllite, tremolite, and aednoiite. Chrysotile Is by far the mast-used variety and accounts for over 953 of U.S. consumption, as noted in Table 1. Croddolite, alto known as blue as* bestos. is imported from South Africa. Because of its high mechanical strength and good resistance to adds 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 flKWiil u Ik* CnMw r.r Sodmr'i MtCtwrM VffiRlf hcM in $u Fnacto, Ciiit, Jan* IS. tg*J. * Metal* Dtv, Niacan Fall*. N.Y. ItSCt Vol 47, No. 611, OcctMSEJt 1975 insulation. Although there are some deposits of anthophylljtc in the U.S., matt of it is imported from Finland. It is used primarily as a filler for polypropylene and in insulating ma terials. A comparison of dw four varieties of asbestos which are of com mercial importance is presented in Table 2. It jhould be noted that there are significant differences between chrysotile and ampluboles 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 Taltlc 3. Based on infor mation from asbestos producers and consumption surveys, it is estimated that the plastics industry uses about 333 of the 800,000 tons consumed an nually, which makes it the largest single user of asbestos fiber. The largest uses of asbestns 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 plasdcs 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 Risers and other as bestos varieties arc sometimes re quired for particular properties. Why Use Chrysotile? Among the several advantages of chrysotile. which set it apart from the amphibotc minerals and account for its widespread and increasing us age. are world-wide availability, me chanical strength, flexibility, positive surface clrarge, 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. Tlic 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 crocidolita and amosite are more hazardous to 01-0205533 AIA-60 the following Congressional purpose: "To assure so far as possible every working nun and woman in the na tion safe and healthful working con dition* and to preserve tmr human resources." The Act established the Occupational Safety and Health Ad ministration (OSHA) within the De partment of Labor, which ha* rc- sponsiliility for administration and enforcement. Research and related functions are handled by the Depart ment of Health, Education and Wel fare fHEW) 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 operation* which arc protected under other federal health and safety laws. In a news release issued January 4. 1072, OSHA announced a Target Health Hazards Program aimed at improving health factors associated with working condition*. The follow ing five substances were designated to he the focus of initial and con certed efforts by OSHA and NIOSH: asbestos, cotton dust, silica. lead, and carbon monoxide. - t 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 fillers per cubic centimeter on July 1. 1976. A peak concentration of 10 fillers per cubic centimeter is not to he 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 deport 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 inliTpiftation of (lie reg ulations has i-ri-iit-d many iniseoncvptuin* alnitit equipment .mil proecdurcs needl'd in prnpcrlv use uxliextm. If exposure limits arc not exceeded. there arc no further com pliance requirement* except fur med ical examination*. Medical examina tions arc required for all employees in any occupation exposed to airborne concentrations of aslicstos filter!. The examinations are relatively simple and should cost im 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 inch materials. This spe cial prolection is not required for any other use of aslicstos unless exposure. I'mits are exceeded. Tins is also true for other itetns such as specially equipped tools, change rooms, clothes laundering, and waste disposal. Res pirators are not a substitute for en gineering controls, hut die 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, job assignments. Caution kiwis are required on prod ucts containing asbestos except where the fibers have licen modified by 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 in clude: dry acoustical spray products and joint cements, umaturated roof ing felt and textiles, and some in sulating products made without ade quate hinders. The labeling of a prod uct does not prnhihit its use. It should lie noted here that in at least 902 of the products containing asliestoc. the fibers are solidly locked into the product thereby presenting little danger of dust generation dur ing normal use and handling of the product.* . EPA Standards Wliereas OSllA is responsible For the protection of the worker, the En vironmental Protection Agency (Ei'A) is charged with improving flic en vironment to winch the general public is exposed. On March 31. 1971, aslicstos, 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 the out side air from asbestos mills, roadxvays, certain manufacturing operations, building demolition, and the spray-oil application of materials used to in 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 15 asbestos bn a dryweight basis. This should significantly reduce omission* to which the gen eral public may lie 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 asliettos. 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. But. liccause of the known serious effects of uncontrolled inha lation of aslicstos minerals in indus try. and uncertainty as in the shape and character of the da-e-rrsponsc curve in man. it would Ik highly im- JOHN L. MYERS. Marketing Manager tor trie Calidria Asbestos Grouo in Union Carbides Metals Div., received his B.S. Oegree in Chemical Engineering from Purdue: University in 1951. Joining Union Carbide triat same year, he served in the Nuclear Division until 1966, when he be came a Research Engineer tn Iho asbestos group. He was promoted to his present position in 1970. Vol. 47, No. 611, Deczxuu 1975 ]y, the plastics industry uses primarily chrysolite asix.'StO'i .mil, in most prixi* ucts. the fibers arc l>x-ked-in to pre vent airixime ntiitaminaiion. Al though asbestos dwt levels arc gen erally lower than expected, industry continues to expend large amounts of time and money to further improvo 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. Clirysorilc 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 Q References (I) Interline. P. E. and Henderson. V., Arch. Envinn. Health, 77, Jig (Nov. 1973). (V) Wagner. 1. C,, Ann. Occup. Hil- lJ. 61 (1972). (3) Wright. O. W.. statement before U.S. Dept, of Lair. Occupational Safety and Health hearing on pro posed occupational asbestos stan dard. March 16. 1972. p. 3. (4) Hammond E. C. and Sdikoff. I. "Relation Of Cigarette Smoking To Risk of Death of Asbestos-Associ- alcil Discus among Insulation Workers in the U-S.A," presented at meeting of tlte Working Croup to Astern Biological Effects of As bestos. Intemaiioual Agency for Re search on Cancer. Lyon. Franca (Oct- 4. 1972). (5) `Report of the Advisory Committee oo Asbestos Cancers,'* Brit, J. In, dmtr. Med, JO, ISO (1973). (6) "Asbestos.'* .Veiionef Safety Nan (Oct. 9. 1973). - (7) "Natiooal Emission Standards for Hanrdous Air Pollutants,' Federal Register, Jt, No. 06. 8820 (April 6, 1973). (8) "Protecting the Ashestos Worker.' Booklet No. I01D37, The Ashestos Information Association/North . America, p 5. (9) Selikotf. 1. j,, Indmtr. Medicine, J9, No. 4. 21 (Aptil 1979) . (10) "Slandanl for Exposure to Asbestos Dust." Federal EegiUtt, J7, No. 110, 11320 nunc 7. 1972). (II) Bayer, S. G, et al, "Equipment and Procedures for Mounting Miltipore Filters and Counting Asbestos Fibres by Phase-Contrast Microscopy." Bureau of Orcup. Safety and Health, U.S. Dept, of Health, Edu cation. tt Welfare (Felt. 1969). (12) "Asbestos Health Question Per plexes Experts." Chem. Eng, Neon, I* (Dee. 10. 1973). . (13) Myers, J. L, "Cjlitlria Aslieslos Pci- lets," ASBESTOS (Oct. 1971). Vou Al, No. 6] 1, December 1975 AIA-60 Asbestos Information Association North America 1660 l Street. N. W. Washington, 0. C. 20036