Document XOKx0beY3nZMNwpzMZxq0rKp4

PLAINTIFF'S EXHIBIT AL-1378 TO: ^ fe. // A c* CM FEBRUARY 1975 SUN MON rue WED THU FRl SAT 1 2 34 5 6 78 0 10 11 12 13 14 15 16 IT 18 10 20 21 22 24 25 26 2T 28 /*) // --tf * 1<M_ 409677 0294 ASBESTOS IN WATER IN THE CHLOR-ALKALI INDUSTRY Presented at The Chlorine Institute, Inc. Seventeenth Chlorine Plant Managers' Seminar New Orleans, Louisiana February 5, 1975 D. R. Beaman, F. P. Boer, C. T. Lichy R. J. Moolenaar, F. W. Spillers, O. C. Taylor, and D. M. Young The Dow Chemical Company 409677 0295 Ft 3 1. H. V/. F. ASBESTOS IN WATER IN THE CHLOR-ALKALI INDUSTRY R. J. Koolenaar, Dow Chemical U.S. Midland, Michigan (Presented at The Chlorine Institute, Inc. Seventeenth Chlorine Plant Managers' Seminar New Orleans, Louisiana, February 5, 1975) Introduction Dr. Charles Kramer, a physician in Dow's Medical Department, addressed the Fourteenth Plant Managers' Seminar at the 1971 Chlorine Institute meeting on the topic "Asbestos and Health"(1). He clearly pointed out that exposure to air-borne asbestos was of serious concern, and that control of industrial exposure to air-borne asbestos was essential. Good engineering procedures, good housekeeping, and careful monitoring of the workroom air were recommended as aids in the control. Since then, air-borne asbestos hazard control has been the topic of a NIOSH criteria document (2), an OSIIA standard (3,4), and an EPA national emission standard (5). Today I wish to focus attention on asbestos in water; to summarize briefly and comment on health effects of exposure to water-borne asbestos, to discuss the analysis of asbestos in water, and to review results obtained in the determination of asbestos levels in diaphragm cell c'nlor-alkali process streams. For those not acquainted with the use of asbestos in the chlor-alkali industry, a brief description is supplied in Appendix A. The chemical and physical properties of asbestos are summarized in Appendix B. Health Effects of Asbestos The health hazards associated with prolonged inhalation of asbestos have been established beyond reasonable doubt. Chronic effects have been found in workers involved in asbestos mining, milling, textile manufacture, and in the insulation industry. The most obvious is asbestosis, a condition not seen in the general population, characterized by breathing difficulties, wheezing, clubbed fingers (caused by oxygen deficiency) and cyanosis (blueness of the skin) . Cancer of the spiratory tract has also been attributed to prolonged asb .os inhalation. This has been discussed in several publi ions, most recently by Eelikcfr and co-workers who studied c or risk of insulation workers in the United States. They found :m incidence of lung cancer about si t i t.'.e that expected in the general population. Selikoff et al (7) concluded thee if asoestos workers smoko cigarettes, trie risk is greatly increased. Another form of cancer associated v.'i th (6) 409677 0296 asbestos is mesothelioma, a very rare form of tumor in the general population. Mesotheliomas most commonly associated v/ith asbestos occur in the linings of the lung and of the abdominal cavity. As a result of these and other observations, both OSHA and EPA have promulgated standards for control of exposure to air-borne asbestos. Epidemiological data from asbestos insulation workers in the United States (6) also shov/ed increased incidence of gastro intestinal cancer in exposed workmen compared v/ith that ex pected in the general population. The asbestos exposure to the GI tract is thought to arise from nasal and throat clearing mechanisms, whereby about 90% of the dust inhaled is swallowed. On the other hand, animal feeding studies have not confirmed this effect, even where amounts fed v/ere extraordinarily large. In studies reported by Gross et al. (8), chrysotile asbestos fibers were fed to rats in food (5% of food weight) for 21 months. There were no deaths in this group and at autopsy no lesions could be found either grossly or microscopically. Another study was reported wherein groups of rats were fed asbestos mixed in butter at levels to provide 5-10 mg/rat weekly for 16-18 weeks. After six months, some rats v/ere killed to assess pathological changes while the others were allowed to survive until they died a natural death. No increased incidences of tumors were observed. Other studies have shown similar results. Very short fibers may not present a significant health hazard. Thus, Gross (9) concluded from his own experiments and from evidence in the literature that short-fibered asbestos dust, i.e. shorter than 5 microns, is incapable of causing fibrosis or cancer. Studies conducted at the National Cancer Institute by Stanton and Wrench (10) suggest that the carcinogenicity of asbestos and fibrous glass is primarily related to the structural shape of these materials rather than to physicochemical properties and that fiber size is of critical importance. In a recent edi torial, Stanton (11) claims that when the pleura of rats are exposed to asbestosjfibers less than 3 microns in diameter and longer than 20 microns are far more carcinogenic than fibers with diameters exceeding 3 microns (regardless of length) or shorter than 20 microns (regardless of diameter). These views are consistent with the OSIIA standard for air-borne asbestos which is concerned only with those fibers greater than 5 microns in length . a a length to diameter ratio of 3 or greater The widespread distribution of asbestos in potable v/ater, foods, and beverages has prompted concern over the effects of ingested asbestos. However, in 1973, the Advisory Committee on Asbestos Cancer of the International Agency for Research on. Cancer (a division of the Worid Health Organization) reported their findings to the Agency Director. As part of their report (12), they state: "such evidence as there is does not indicate any risk from ashes to fibers present in water, food, beverage, or drugs." 4096770297 -2- Analysis of Asbestos in Water Microscopy is the technique of choice for the analysis of asbestos because it gives information on fiber dimensions, and also it provides a direct measurement of the number of fibers per unit volume (expressed here in millions of fibers per liter, MFPL). These two parameters appear to be of prime importance in assessing the human physiological response to asbestos fibers. The data may also be converted to a weight basis if desired.* For particle sizes of interest in the chlor-alkali industry, 1 MFPL corresponds to about 0.01 microgram per liter or 0.00001 ppm (w/v). In most water samples of interest the concentration of asbestos is very low, the fibers have small diameters (0.034 - 0.7 microns) and the length to diameter ratio is usually less than 300. Such samples also contain other solids, some of which appear to be fibrous in the microscope, but are not asbestos. In fact, in our studies we have seen samples where the asbestos content ranged from 0-100% of the total fiber content. To resolve these complicating factors. Dr. D. R. Beaman and D. M. File of our Midland Analytical Laboratories, have developed a quantitative method which includes fiber identification, based on the simultaneous measurement of morphology, crystal structure and chemical composition. They use a transmission electron microscope equipped v/ith selected area electron, diffraction and an energy dispersive spectrometer. The fiber concentrations are corrected for losses encountered during sample preparation and for ambiquities in the selected area electron diffraction patterns. Even v/ith this sophisticated array of equipment (costing up to $150,000), the time required for analysis of a single, sample is about eight hours. Furthermore, the method is tedious - in samples v/ith low fiber concentration, up to 2000 fields of view are counted to provide statistical signif icance. The results are believed to be accurate to within a factor of two or three, and this is by far the roost reliable method currently available for the determination of asbestos in liquid samples. A detailed description of the method has been submitted for publication. Levels of Asbestos in Water Asbestos is ubiquitous. It has been widely found in natural waters throughout the North American continent. Literature reports indicate most waters examined so far contain some mineral fibers. Much of this is probably of natural origin. *The formula for conversion of MFPL to a '/eight per unit volume basis is the follow in.;: Asbestos level ir. milligram/! iter - 2.3 x 10 ^ (T) (MFPL) where z is the mean fiber fiber density of 2.5 g/m.l of 340 angstroms. length in microns. This ass end a solid particle with a es a ametor 409677 0298 -3- Erosion from outcroppings of serpentine- or amphibole-containing rock by streams will transport fibers into potable water supplies. Regions of the Unites States known or believed to contain ser pentine or amphibole minerals include a large portion of the mountainous regions of the Eastern and Western States (13,14). Underground water sources may also be subject to natural con tamination but the available data are very limited (13). Further distribution of asbestos into regions where serpentine or amphibole minerals are not indigenous can occur through transport by the wind. The presence of asbestos in melted snow, which contributes to fiber levels in local surface waters (15), indicates that wind may play an important role in the dispersal of asbestos. Amphibole fibers in unfiltered drinking water from Lake Superior at Duluth, Minnesota, have been attributed to discharge of taconite tailings into the lake (16) . Reported levels are 1-30 million fibers per liter (MFPL). Concentrations of asbestos fibers in water in 22^ communities reported by Kay (17,18) vary from 0.1 to 3.9 MFPL. An earlier study (15) of tap water from three major cities gave values between 2.0 and 4.4 MFPL. One sample of drinking water drawn from a small lake in an asbestos mining region showed 170 MFPL (15) . Levels of 2 to 12 MFPL found in beers, sherries, ports, ver mouths, and soft drinks have been attributed to the extensive use of asbestos in filtration processes (15). These levels correspond to only about 0.0001 mg asbestos in one bottle of beer. Comparison of results from one study to another will be fraught with uncertainty until analytical methods are standardized. Analytical techniques differ considerably from one laboratory to another. Within the present state of the art, it is quest ionable whether any analysis based solely on electron microscopy is accurate to better than an order of magnitude (14) . Finally, direct comparison of data for samples containing different asbestos minerals is intrinsically difficult. Asbestos in Chlor-A.lkali Process Streams The above findings allow us to view in perspective the levels of asbestos encountered in diaphragm cell process streams and products. Our measurements, based on very limited sampling, have given the following results: -4- 409677 0299 Sample MFPL Mean Asoestos Levels Mean Length Microns ppm (w/v) Cell Liquor Unfiltered Filtered 40,000 400 6 0.6 1 0.001 50% Caustic 3,000 3 0.02 Viastewater Effluent 150 4 0.001 Steam Condensate (partially derived from caustic evaporators) 200* -- - -- Determined by electron microscopy alone, with no-chemical analysis or structure confirmation. The distribution of fiber lengths is fairly broad, but very few fibers longer than 20 microns have been observed. The significance of the short average fiber lengths was discussed above. The level in cell liquor, the product stream coming directly from the electrolytic cells, is by far the highest. Some of the fibers are returned to the cells with the salt precipitated during the evaporation process. Surprisingly, some fibers apparently are entrained in the steam from caustic evaporation. The implications of this observation will depend on the dis position of evaporator steam, which undoubtedly varies with manufacturing location. Filtration of cell liquor resulted in 99% removal of asbestos by fiber count and over 99.9% removal on a weight basis. Work is in progress to optimize the conditions for fiber removal by this technique. Conclusions 1. An analytical method has been developed which provides both positive identification and quantification of asbestos fibers in water. It is reliable but tedious and slew for routine use. 2. Results from very limited sampling show that process streams and products from diaphragm cell chlor-alkali plants contain, asbestos, but average fiber lengths are 6 microns or less. 3. Most of the asbestos, especially the longer fibers, can be removed from cell liquor by filtration. 409677 0300 4. Asbestos of natural origin or dispersed through man's activities is found in drinking water, beverages, food, and drugs. 5. Health authorities have stated they do not'view the ingestion of small amounts of asbestos (particularly short fiber asbestos) as a risk to man. Recommendations 1. An industry-wide cooperative program should be initiated to standardize analytical techniques for the determination of asbestos fibers in liquid samples and to develop a simplified method, e.g. atomic absorption, for routine use. The Chlorine. Institute might serve as a focal point for this activity. 2. Each chlor-alkali producer using asbestos diaphragms should carry out a survey to determine the distribution of asbestos in his liquid effluent streams and products. 3. Water-borne asbestos originating from diaphragm cell operations has not been shown to be a health hazard; nevertheless, prudence dictates the need to develop methods for controlling the level of asbestos in products, process streams, and water effluents. 4. Medical and toxicological experts in government, academia and industry should cooperate to develop a better under standing of the effects of the ingestion of short fiber asbestos by human beings. 409677 0301 -6- REFERENCES 1. C. G. Kramer, "Asbestos and Health," presented at the Chlorine Institute, Inc., Fourteenth Chlorine Plant Managers' Seminar, New Orleans, Louisiana, February 3, 1971. 2. "Occupational Exposure to Asbestos." U.S. Department of Health, Education and Welfare, Public Health Service, Health Services and Mental Health Administration, National Institute for Occupational Safety and Health, 1972. 3. Federal Register 37' No. 202, 22142 (1972). 4. Federal Register 39, No. 125, 23543 (1974). 5. Federal Register 38, No. 66, 8820 (1973). 6. .1. J. Selikoff, E. C. Hammond, and H. Seidman, Insulation Hyg. Progr. Rep. 6_, No. 3 (Fall 1974) . 7. I. J. Selikoff, E. C. Hammond, and J. C'nurg, J. Amer. Med. Ass. 204, 104 (1968). 8. P. Gross, R. A. Harley, L. M. Swinburne, J. M. G. Davis, and W. B. Greene, Arch. Environ. Health 9, 341 (1974) . 9. P. Gross, Arch. Environ. Health 2, 115 (1974). 10. M. F. Stanton and C. Wrench, J. Nat. Cancer Inst. 48, 797 (1972). 11. M. P. Stanton, J. Nat. Cancer Inst. 2, 633 (1974) . 12. Advisory Committee Report, Brit. J. Ind. Med. 0, 180 (1973). 13. M. Kuschner, R.- Lee, G. G. Robeck, J. R. Rossum, M. A. Schneiderman, E. W. Taylor, and G. W. Wright, J. Amer. Water Works Ass. 6 (9), Part 2, p. 1 (1974). 14. H. L. Olson, J. Amer. Water Works Ass. 6 (9), 515 (1974). 15. H. M. Cunningham and R. Pontefract, Nature, 232, 332 (1971). 16. P. M. Cook, G. E. Glass, and J. H. Tucker, Science, 185, 853 (1974). 17 G. H. Kay, Water and Pollut. Contr. (Toronto) 111 (9), 33 (1973). 13. G. II. Ka y , J. Water Works 56 (9), 513 (1974). 409677 0302 -7- APPENDIX A DSE OF ASBESTOS IN THE MANUFACTURE OF CHLORINE AND CAUSTIC SODA The bulk of the chlorine and caustic soda produced in North America is by the electrolysis of sodium chloride brine using either the diaphragm, cell process or the mercury cell process. The diaphragm prpcess uses an asbestos separator between the anode side of the cell and the cathode side. The mercury process uses no separator. In a typical diaphragm cell, saturated brine is fed to the anode compartment of the cell, then flows through the diaphragm to the cathode compartment where sodium hydroxide is formed. Flow through the diaphragm is maintained by a differential brine head. During operation, hydrogen and sodium hydroxide form at the cathode and chlorine forms at the anode. The two gases, chlorine and hydrogen, bubble up through the liquid on either side of the diaphragm and are removed from the top of the cell. The caustic soda together with the depleted brine leaves the cell as a dilute solution of sodium hydroxide and sodium chloride, known in the industry as "cell effluent" or "cell liquor." More concentrated solutions of caustic soda are obtained by evaporation of the cell liquor, whereupon sodium chloride crystallizes from solution. The asbestos diaphragm is formed by vacuum drawing asbestos from a slurry directly on to the cathode, which is normally made of woven steel wire or punched steel plate. The chlorine cell diaphragm serves several purposes: 1. . Prevents mixing of the acid side of the cell (anolyte) with the basic side (catholyte). 2. Prevents mixing of the chlorine and hydrogen gas which can form explosive mixtures. 3. Prevents the hydroxyl ion, formed at the cathode, from migrating to the anode, which would cau:-a discharge of oxygen and oxidation of the anode surfs Asbestos has been valued as an excellent diaphragm material due to its relatively good chemical and temperature resistance. Also, unlike other materials, it tends to help regulate the electrolytic process by changing its actual porosity with changing electrical current loads and changing acid/basic conditions. 49S77 0303 APPENDIX B CHEMICAL AND PHYSICAL PROPERTIES OF ASBESTOS The term asbestos designates certain naturally-occurring in organic fibers belonging to the amphibole and serpentine groups of minerals. It also designates an important industrial com modity which is heat resistant, chemically resistant, and capable of being spun into flexible yarn. These unique prop erties make asbestos an exceptionally useful material, and consumption in the United States has risen rapidly to the 800,000 ton per year level. Its application in the chlor-alkali industry represents just one of over 300 industrial uses of asbestos, which include very large volumes consumed in asbestos cement, floor tiles, asbestos paper, asbestos textiles, friction materials, and gaskets (1). The chlor-alkali industry uses less than 1% of the total asbestos produced. Chrysotile is the most important commercial form of asbestos and is.the form generally used in the chlor-alkali industry. It is a member of the serpentine group of phyllosilicates. It is usually mined from large bodies of serpentinite rock, where it occurs in cross- or slip-fiber veins (2). These veins vary in thickness from a fraction of a millimeter to several cent imeters. Non-fibrous varieties of serpentine minerals (antigorite, lizardite) are also usually present, as are small quantities of brucite and magnetite. The remaining five minerals clas sified as asbestos--amosite, anthophyllite, tremolite, actinolite, and crocidolite--belong to the amphibole group of inosilicates. Together the amphibole forms of asbestos account for less than 5% of commercial production. Consumption in the chlor-alkali industry is also predominantly of chrysotile asbestos, although crocidolite (or "blue asbestos") has occasionally been used. Asbestos minerals have quite different elemental compositions, and show significant differences in specific gravity and retractive index (3) as seen below: Mineral Empirical Formula Specific Gravity Refractive Index Chrysotile Mg3Si205 (OH)4 2.4 - 2.5 1.49 - 1.57 Tremolite ca2Mg5Si8022(H)2 2.9 - 3.2 1.60 - 1.65 Actinolite Ca-,(Mg,Fe )ig022(OH)2 3.0 - 3.5 1.62- 1.68 Anthophy11ite Arr.osi fce Mg_Sig22 (C>!l) 2 (Mg,Fe2 + ) 7Sig022 (0!:) 2 2.9 - 3.5 2.6 - 3.0 1.60 - 1.66 1.56 -- 1.70 Crocidolite Na^FOg Fc2 Sig020 (OH)9 3.0 - 3.5 1.69 - 1.71 409677 0304 The ideal chemical composition of chrysotile approximates 44% MgO, 43% Sidp, and 13% H_0, although small amounts of other elements sucn as iron, aluminum, and nickel may substitute for magnesium in the structure (2,4). Chrysotile will decompose under severely acid conditions (5), whereby essentially all the MgO and 1^0 are dissolved, as indicated by a 56% weight loss, leaving Dehind a silica skeleton. Amphibole forms of asbestos possess superior resistance to agid. Chrysotile also decomposes at elevated temperatures (6,7) and exhibits an intense dehydroxylation endotherm at approximately 650C and an exotherm at 820C which is believed to be assoc iated with the formation of forsterite (Mg2SiO.) and/or enstatite (MgSiO^). The nature of chrysotile bears an important relationship to its atomic structure. Together with the other serpentine minerals, lizardite and antigorite, chrysotile is classed as a phyllosilicate or "sheet-like" silicate. All three minerals are considered polymorphs of the same basic chemical composition, and are built up of similar, infinite, two-dimensional sheets. Each individual sheet consists of a silicate layer and a magnesium hydroxide layer, with an overall thickness of 7.3A., A small, but important, difference in the preferred lattice spacing of the silicate and magnesium hydroxide layers appears to cause the wide variations in morphology of serpentine minerals In chrysotile, the strain caused by this difference is relieved when several adjacent sheets "curl up" to form the hollow tube structure that constitutes an individual chrysotile filament. High resolution electron micrographs of chrysotile fibers in cross-section have shown both the multiple spiral pattern and the.characteristic hollow center of this structure very clearly (8). The three known varieties of chrysotile are related to the manner in which these spirals form. Clino-chrysotile, the most common type, curves around the a axis of its monoclinic unit cell. In ortho-chrysotile, the unit cell is orthorhombic, but curvature remains around a. A rarer form, parachrysotile, also has an orthorhombic unit cell but is' curved about the b axis. Antigorite and lizardite must relieve the same strain, but they do so by quite different mechanisms: antigorite forms a "wavy" sheet structure with a very long unit cell repeat, while lizardite generally contains other elements that sub stitute within the silicate or magnesium hydroxide layers in a manner that equalizes the lattice spacings. It is interesting to note that, although the differences in morphology between the filament structure of chrysotile and the plate-like or lath-like habit of ancigorite or lizardite are conspicuous, the similarities in structure on the atomic scale make it relatively difficult to distinguish these serpentine minerals from each other by X-ray pov.'der diffraction (2). 409677 0305 -2- The characteristic morphology of chrysotile fibers can be observed with the transmission electron microscope, an impor tant aid in their identification. The interior cavity of a chrysotile fiber is usually visible and has an average inner diameter of 80-100A. However, a hollow center is not always seen (8), and amorphous material may be observed within the interior of the filaments (2). Outer diameters of chrysotile fibers range from 150 to 1000A. The mean diameter is about 340A in the industrial samples we have examined, but other reports (2,8) cite mean diameters from 250 to 500A. The narrowness of its individual filaments gives rise to one of the most important physical properties of chrysotile asbestos, namely, its vejjy high specific surface area which can be in excess of 10 ni /g. Fibers of the amphibole varieties of asbestos are considerably larger in cross-section (9). The ratio of length to diameter, known as the aspect ratio, may be quite large for individual chrysotile fibrils. Aspect ratios of several hundred are normal for most vein materials, but very short fibers with aspect ratios of 5 to 10 may be found in the serpentinite matrix of many ore bodies (2). Mean aspect ratios in samples related to the chlor-alkali process range from about 30 to over 400, corresponding to average lengths up to about 15 microns. Obviously, any processing which tends to shear or grind the asbestos will both increase the number of fibers and decrease their aspect ratio. Chrysotile may occur either as individual fibrils or as bundles of fibrils. Since the diameters of single chrysotile filaments are only a fraction of the wave length of visible light, in dividual fibers cannot be resolved visually, even with the best optical microscope. The measurement of chrysotile by optical methods is therefore confined to material which may occur as bundles 'or other filamentary masses. The electron microscope is by far the most useful instrument for identification and quantification of individual chrysotile fibers. With an instrument equipped with accessories for selected area electron diffraction and energy dispersive X-ray spectroscopy, the morphological data can be supplemented with the diffraction pattern and quantitative elemental identification applied to individual particles. When somewhat larger quantities are involved, a successful analytical technique--atomic absorption spectroscopy (10), infrared spectroscopy (11), X-ray diffraction (12), differential thermal analysis (6), optical microscopy/index of refraction (3)--can be devised by exploiting some of the characteristic chemical and physical properties discussed .above. -3- 409677 0306 REFERENCES (1) P. B. Meijer and W. E. DeKoning-Pierens, TNO Nieuws 27, 661 (1972) (Eng.). (2) F. A. Hampton, Siemens Review XLI, 75 (1975). (3) W. C. McCrone and I. M. Stewart, American Laboratory 6_ (4) , 13 (1974); Y. Julian and W. C. McCrone, The Microscope 18^ 1 (1970) . (4) E. J. W. Whittaker and F. J. Wicks, Amer. Mineral. 55., 1025 (1970). (5) M. S. Badollet, Can. Mining Met. Bull. No. 468, 237 (1951). (6) J. P. Schelz, Thermochimica Acta , 197 (1974). (7) L. A. Drobyshev and Ya. Ya. Govorova, Kristallografiya 16, 544 (1971) (Russ.). (8) K. Yada, Acta Cryst. 2_3, 704 (1967) . (9) D. V. Rosato, "Asbestos, Its Industrial Applications." Reinhold Publishing Corp., New York, 1959, p. 43. (10) R. G. Keenan and J. R. Lynch,- Amer. Ind. Hyg. Ass., J. 31, 587 (1970). (11) (12) J. A. Gadsden, J. Parker, and W. L. Smith, Atmos. Environ. 4, 667 (1970). c K. Goodhead and R. W. Martindale, Analyst (London) 94, 985 (1969). 409677 0307 ASBESTOS IN WATER IN THE CHLOR-ALKALI INDUSTRY Presented at The Chlorine Institute, Inc. Seventeenth Chlorine Plant Managers' Seminar New Orleans, Louisiana February 5, 1975 D. R. Beaman, F. P. Boer, C. T. Lichy R. J. Moolenaar, F. W. Spillers, O. C. Taylor, and D. M. Young The Dow Chemical Company 409677 0308 ASBESTOS IN WATER IN THE CHLOR-ALKALI INDUSTRY ' R. J. Moolenaar, Dow Chemical U.S. Midland, Michigan (Presented at The Chlorine Institute, Inc. Seventeenth Chlorine Plant Managers' Seminar New Orleans, Louisiana, February 5, 1975) Introduction Dr. Charles Kramer, a physician in Dow's Medical Department, addressed the Fourteenth Plant Managers' Seminar at the 1971 Chlorine Institute meeting on the topic "Asbestos and Health"(1). He clearly pointed out that exposure to air-borne asbestos was of serious concern, and that control of industrial exposure to air-borne asbestos was essential. Good engineering procedures, good housekeeping, and careful monitoring of the workroom air were recommended as aids in the control. Since then, air-borne asbestos hazard control has been the topic of a NIOSK criteria document (2), an OSHA standard (3,4), and an EPA national emission standard (5) . Today I wish to focus attention on asbestos in water; to summarize briefly and comment on health effects of exposure.to water-borne asbestos, to discuss the analysis of asbestos in water, and to review results obtained in the determination of asbestos levels in diaphragm cell chlor-alkali process streams. For those not acquainted with the use of asbestos in the chlor-alkali industry, a brief description is supplied in Appendix A. The chemical and physical properties of asbestos are summarized in Appendix B. Health Effects of Asbestos The health hazards associated with prolonged inhalation of asbestos have been established beyond reasonable doubt. Chronic effects have been found in workers involved in asbestos mining, milling, textile manufacture, and in the insulation industry. The most obvious is asbestosis, a condition not seen in the general population, characterized by breathing difficulties, 'wheezing, clubbed fingers (caused by oxygen deficiency) and cyanosis (blueness of the skin) . Cancer of the respiratory tract has also been attributed to prolonged asbestos inhalation. This has been discussed in several publications, most recently by Se like ft and co-v. orkers (6) who studied cancer risk of insulation v.'o rka cs in the Uni States. They found an incidence of lung cancer about si x Lines that expected in the general population. Selikoff et ai (7) concluded that if asbestos workers smoke cigarettes, the rL- J>. hc>' AV is greatly increased. Another form of cancer associated v:i th 409677 0309 asbestos is'mesothelioma, a very rare form of tumor in the general population. Mosotheliomas most commonly associated v/ith asbestos occur in the linings of the lung and of the abdominal cavity. As a result of these and other observations, both OSHA and EPA have promulgated standards for control of exposure to air-borne asbestos. Epidemiological data from asbestos insulation workers in the United States (6) also showed increased incidence of gastro intestinal cancer in exposed workmen compared with that ex pected in the general population. The asbestos exposure to the GI tract is thought to arise from nasal and throat clearing mechanisms, whereby about 90% of the dust inhaled is swallowed. On the other hand, animal feeding studies have not confirmed this effect, even where amounts fed were extraordinarily large. In studies reported by Gross et al. (8), chrysotile asbestos fibers were fed to rats in food (5% of food weight) for 21 months. There were no deaths in this group and at autopsy no lesions could be found either grossly or microscopically. Another study was reported wherein groups of rats were fed asbestos mixed in butter at levels to provide 5-10 mg/rat weekly for 16-18 weeks. After six months, some rats were killed to assess pathological changes while the others were allowed to survive until they died a natural death. No increased incidences of tumors were observed. Other studies have shown similar results. Very short fibers may not present a significant health hazard. Thus, Gross (9) concluded from his own experiments and from evidence in the literature that snort-fibered asbestos dust, i.e. shorter than 5 microns, is incapable of causing fibrosis or cancer. Studies conducted at the National Cancer Institute by Stanton and Wrench (10) suggest that the carcinogenicity of asbestos and fibrous glass is primarily related to the structural shape of these materials rather than to physicochemical properties, and that fiber size is of critical importance. In a recent edi torial, Stanton (11) claims that when the pleura of rats are exposed to asbestos,fibers less than 3 microns in diameter and longer than 20 microns are far more carcinogenic than fibers with diameters exceeding 3 microns (regardless of length) or shorter than 20 microns (regardless of diameter). These views are consistent v/ith the OSHA standard for air-borne asbestos which is cor rerned only v/ith those fibers greater than 5 microns in length .da length to diameter ratio of 3 or greater. The v/idespread dis rind beverages has asbestos. Hovevor Cancer of the Ir.te division of the to the Agency Dire "such evidence as fibers present in ibution ol asbestos in potable water, foods, crpeod concern over the effects of ingested :..n 1073 , trie A.dvisory Committee on Asbestos at: or.nl Agency for Research on Cancer (a d health Organization) reported their findings or. As part of their report (12), they state: ere is dots not in:: lento any risk from asbestos ter, foo hover ay or drugs." 409677 0310 -2- Analysis of 'Asbestos in Water Microscopy is the technique of choice for the analysis of asbestos because it gives information on fiber dimensions, and also it provides a direct measurement of the number of fibers per unit volume (expressed here in millions of fibers per liter, MFPL). These two parameters appear to be of prime importance in assessing the human physiological response to asbestos fibers. The data may also be converted to a weight basis if desired.* For particle sizes of interest in the chlor-alkali industry, 1 MFPL corresponds to about 0.01 microgram per liter or 0.00001 ppm (w/v). In most water samples of interest the concentration of asbestos is very low, the fibers have small diameters (0.034 - 0.7 microns) and the length to diameter ratio is usually less than 300. Such samples also contain other solids, some of which appear to be fibrous in the microscope, but are not asbestos. In fact, in our studies we have seen samples where the asbestos content ranged from 0-100% of the total fiber content. To resolve these complicating factors. Dr. D. R. Beaman and D. M. File of our Midland Analytical Laboratories, have developed a quantitative method which includes fiber identification, based on the simultaneous measurement of morphology, crystal structure and chemical composition. They use a transmission electron microscope equipped with selected area electron diffraction and an energy dispersive spectrometer. The fiber concentrations are corrected for losses encountered during sample preparation and for ambiquities in the selected area electron diffraction patterns. Even with this sophisticated array of equipment (costing up to $150,000), the time required for analysis of a single, sample is about eight hours. Furthermore, the method is tedious - in samples with low fiber concentration, up to 2000 fields of view are counted to provide statistical signif icance. The results are believed to be accurate to within a factor of two or three, and thisis by far the most reliable method currently available for the determination of asbestos in liquid samples. A detailed description of the method has been submitted for publication. Levels of Asbestos in Water Asbestos is ubiquitous. It has been widely found in natural waters throughout the North American continent. Literature reports indicate most waters examined so far contain some mineral fibers. Much of this is probably of natural origin. *The formula for conversion of MFPL to a weight per unit volume basis is the following: Asbestos level in milligram/iitcr -- 2.3 x 10 ^ (T) (MFPL) where 1 is the mean fiber length in microns. This assumes a fiber density of 2.5 g/rr.l and a solid particle with a diameter of 340 angstroms. 409677 0311 -3- Erosion from outcroppings of serpentine- or amphibole-containing rock by streams will transport fibers into potable water supplies. Regions of the Unites States known or believed to contain ser pentine or amphibole minerals include a large portion of the mountainous regions of the Eastern and Western States (13,14). Underground water sources may also be subject to natural con tamination but the available data are very limited (13). Further distribution of asbestos into regions where serpentine or amphibole minerals are not indigenous can occur through transport by the wind. The presence of asbestos in melted snow, which contributes to fiber levels in local surface waters (15), indicates that wind may play an important role in the dispersal of asbestos. Amphibole fibers in unfiltered drinking water from Lake Superior at Duluth, Minnesota, have been attributed to discharge of taconite tailings into the lake (16). Reported levels are 1-30 million fibers per liter (MFPL). Concentrations of asbestos fibers in water in 22^ communities reported by Kay (17,18) vary from 0.1 to 3.9 MFPL. An earlier study (15) of tap water from three major cities gave values between 2.0 and 4.4 MFPL. One sample of drinking water drawn from a small lake in an asbestos mining region showed 170 MFPL (15). Levels of 2 to 12 MFPL found in beers, sherries, ports, ver mouths, and soft drinks have been attributed to the extensive use of asbestos in filtration processes (15). These levels correspond to only about 0.0001 mg asbestos in one bottle of beer. Comparison of results from one study to another will be fraught with uncertainty until analytical methods are standardized. Analytical techniques differ considerably from one laboratory to another. Within the present state of the art, it is quest ionable whether any analysis based solely on electron microscopy is accurate to better than an order of magnitude (14) . Finally, direct comparison of data for samples containing different asbestos minerals is intrinsically difficult. Asbestos in Chlor-Alkali Process Streams The above findings allow us to view in perspective the levels of asbestos encountered in diaphragm cell process streams and products. Our measurements, based on very limited sampling, have given the following results: 409677 0312 Sample MFPL Mean Asoestos Levels Mean Length Microns ppm (w/v) Cell Liquor Unfiltered Filtered 40,000 400 6 0.6 1 0.001 50% Caustic 3,000 3 0.02 Wastewater Effluent Steam Condensate (partially derived from Oaustic evaporators) 150 200* 4 0.001 -- Determined by electron microscopy alone. with no- chemical analysis or structure confirmation. The distribution of fiber lengths is fairly broad, but very few fibers longer than 20 microns have been observed. The significance of the short average fiber lengths was discussed above. The level in cell liquor, the product stream coming directly from the electrolytic cells, is by far the highest. Some of the fibers are returned to the cells with the salt precipitated during the evaporation process. Surprisingly, some, fibers apparently are entrained in the steam from caustic evaporation. The implications of this observation will depend on the dis position of evaporator steam, which undoubtedly varies with manufacturing location. Filtration of cell liquor resulted in 99% removal of asbestos by fiber count and over 99.9% removal on a weight basis. Work is in progress to optimize the conditions for fiber removal by this technique. Conclusions 1. An analytical method has been developed which provides both positive identification and quantification of asbestos fibers in water. It is reliable but tedious and slow for routine use. 2. Results from very limited sampling shov.- that process streams and products from diaphragm cell chior-aikali plants contain asbestos, but average fiber lengths are 6 microns or less. 3. Most of the asbestos, especially the longer fibers, can he removed from cell liquor by filtration. 409677 0313 4. Asbestos of natural origin or dispersed through man's activities is found in drinking water, beverages, food, and drugs. 5. Health authorities have stated they do not view the ingestion of small amounts of asbestos (particularly short fiber asbestos) as a risk to man. Recommendations 1. An Industry-wide cooperative program should be initiated to standardize analytical techniques for the determination of asbestos fibers in liquid samples and to develop a simplified method, e.g. atomic absorption, for routine use. The Chlorine. Institute might serve as a focal point for this activity. 2. Each chlor-alkali producer using asbestos diaphragms should carry out a survey to determine the distribution of asbestos in his liquid effluent streams and products. 3. Water-borne asbestos originating from diaphragm cell operations has not been shown to be a health hazard; nevertheless, prudence dictates the need to develop methods for controlling the level of asbestos in products, process streams, and water effluents. 4. Medical and toxicological experts in government, academia and industry should cooperate to develop a better under standing of the effects of the ingestion of short fiber asbestos by human beings. 409677 0314 -C- REFERENCES 1. C. G. Kramer, "Asbestos and Health," presented at the Chlorine Institute, Inc., Fourteenth Chlorine Plant Managers' Seminar, New Orleans, Louisiana, February 3, 1971. 2. "Occupational Exposure to Asbestos." U.S. Department of Health, Education and V7elfare, Public Health Service, Health Services and Mental Health Administration, National Institute for Occupational Safety and Health, 1972. 3. Federal Register 37, No. 202, 22142 (1972). 4. Federal Register 39^, No. 125, 23543 (1974) . 5. Federal Register 38, No. 66, 8820 (1973). 6. .1. J. Selikoff, E. C. Hammond, and H. Seidman, Insulation Hyg. Progr. Rep. 6_, No. 3 (Fall 1974) . 7. I. J. Selikoff, E. C. Hammond, and J. Churg, J. Amer. Med. Ass. 204, 104 (1968). 8. P. Gross, R. A. Harley, L. M. Swinburne, J. M. G. Davis, and W. B. Greene, Arch. Environ. Health 29_, 341 (1974) . 9. P. Gross, Arch. Environ. Health 2, 115 (1974). 10. M. F. Stanton and C. Wrench, J. Nat. Cancer Inst. 48, 797 (1972). 11. M. F. Stanton, J. Nat. Cancer Inst. 52^, 633 (1974) . 12. Advisory Committee Report, Brit. J. Ind. Med. 3, 180 (1973) . 13. M. Kuschner, R.- Lee, G. G. Robeck, j. R. Rossum, M. A. Schneiderman, E. W. Taylor, and G. W. Wright, J. Amer. Water Works Ass. (9), Part 2, p. 1 (1974). 14. H. L. Olson, J. Amer. Water Works Ass. 6 (9), 515 (1974). 15. H. M. Cunningham and R. Pontefract, Nature, 232, 332 (1971). 16. P. M. Cook, G. E. Glass, and J. H. Tucker, Science, 185, 853 (1974). 17. G. H. Kay, Water and Pollut. Contr. (Toronto) 111 (5), 33 (1973). 18. G. II. Kay, J, Amer. Water Works Ass. 66 (9), 513 (19 74). 409677 0315 -7- APPENDIX- A USE OF ASBESTOS IN THE MANUFACTURE OF CHLORINE AND CAUSTIC SODA The bulk of the chlorine and caustic soda produced in North America is by the electrolysis of sodium chloride brine using either the diaphragm cell process or the mercury cell process. The diaphragm process uses an asbestos separator between the anode side of the cell and the cathode side. The mercury process uses no separator. In a typical diaphragm cell, saturated brine is fed to the anode compartment of the cell, then flows through the diaphragm to the cathode compartment where sodium hydroxide is formed. Flow through the diaphragm is maintained by a differential brine head. During operation, hydrogen and sodium hydroxide form at the cathode and chlorine forms at the anode. The two gases, chlorine and hydrogen, bubble up through the liquid on either side of the diaphragm and are removed from the top of the cell. The caustic soda together with the depleted brine leaves the cell as a dilute solution of sodium hydroxide and sodium chloride, known in the industry as "cell effluent" or "cell liquor." More concentrated solutions of caustic soda are obtained by evaporation of the cell liquor, whereupon sodium chloride crystallizes from solution. The asbestos diaphragm is formed by vacuum drawing asbestos from a slurry directly on to the cathode, which is normally made of woven steel wire or punched steel plate. The chlorine cell diaphragm serves several purposes: 1. Prevents mixing of the acid side of the cell (anolyte) with the basic side (catholyte). 2. Prevents mixing of the chlorine and hydrogen gas which can form explosive mixtures. 3. Prevents the hydroxyl ion, formed at the cathode, from migrating to the anode, -which would cau:;:: discharge of oxygen and oxidation of the anode surfa Asbestos has been valued as an excellent diaphragm material due to its relatively good chemical and temperature resistance. Also, unlike other materials, it tends to help regulate the electrolytic process by changing its actual porosity with changing electrical current loads and changing ucid/oasic conditions. 409677 0316 APPENDIX B CHEMICAL AND PHYSICAL PROPERTIES OF ASBESTOS The term asbestos designates certain naturally-occurring in organic fibers belonging to the amphibole and serpentine groups of minerals. It also designates an important industrial com modity which is heat resistant, chemically resistant, and capable of being spun into flexible yarn. These unique prop erties make asbestos an exceptionally useful material, and consumption in the United States has risen rapidly to the 800,000 ton per year level.. Its application in the chlor-alkali industry represents just one of over 300 industrial uses of asbestos, which include very large volumes consumed in asbestos cement, floor tiles, asbestos paper, asbestos textiles, friction materials, and gaskets (1). The chlor-alkali industry uses less than 1% of the total asbestos produced. Chrysotile is the most important commercial form of asbestos and is.the form generally used in the chlor-alkali industry. It is a member of the serpentine group of phyllosilicates. It is usually mined from large bodies of serpentinite rock, where it occurs in cross- or slip-fiber veins (2). These veins vary in thickness from a fraction of a millimeter to several cent imeters. Non-fibrous varieties of serpentine minerals (antigorite, lizardite) are also usually present, as are snail quantities of brucite and magnetite. The remaining five minerals clas sified as asbestos--amosite, anthophyllite, tremolite, actinolite, and crocidolite--belong to the amphibole group of inosilicates. Together the amphibole forms of asbestos account for less than 5% of commercial production. Consumption in the chlor-alkali industry is also predominantly of chrysotile asbestos, although crocidolite (or "blue asbestos") has occasionally been used. Asbestos minerals have quite different elemental compositions, and show significant differences in specific gravity and re fractive index (3) as seen below: Specific Refractive MineralEmpirical FormulaGravity___________ Index Chrysotile Tremolite Actinolite Anthophyllite Amosite Mg3Si205(OH)4 Ca2H%Si822(OH>2 Ca-(Mg,Fe2 + )rSio0_9(OH) ,, 2 j S 22 Mg7Sis22 2 (Mg,Fe2+)7Si8022(0H)2 2.4 - 2.5 2.9 - 3.2 3.0 - 3.5 2.9 - 3.5 2.6 - 3.0 1.49 - 1.57 1.60 - 1.65 1.52 -- 1.63 1.60 - 1.66 1.56 -- 1.70 Crocidolite Na2Fe3 iC2 Sl322(0h)2 3.0 - 3.5 1.69 -- 1.71 409677 0317 The ideal chemical composition of chrysotile approximates 44% MgO, 43% SiO_, and 13% lUO, although small amounts of other elements sucn as iron, aluminum, and nickel may substitute for magnesium in the structure (2,4). Chrysotile will decompose under severely acid conditions (5) , whereby essentially all the MgO and 1^0 are dissolved, as indicated by a 56% weight loss, leaving Dehind a silica skeleton. Amphibole forms of asbestos possess superior resistance to agio. Chrysotile also decomposes at elevated temperatures (6,7) and exhibits an intense dehydroxylation endotherm at approximately 650C and an exotherm at 820C which is believed to be assoc iated with the formation of forsterite (Mg_SiO.) and/or enstatite (MgSiQ^). The nature of chrysotile bears an important relationship to its atomic structure. Together with the other serpentine minerals, lizardite and antigorite, chrysotile is classed as a pnyllosilicate or "sheet-like" silicate. All three minerals are considered polymorphs of the same basic chemical composition, and are built up of similar, infinite, two-dimensional sheets. Each individual sheet consists of a silicate layer and a magnesium hydroxide layer, with an overall thickness of 7.3A. A small, but important, difference in the preferred lattice spacing of the silicate and magnesium hydroxide layers appears to cause the wide variations in morphology of serpentine minerals In chrysotile, the strain caused by this difference is relieved when several adjacent sheets "curl up" to form the hollow tube structure that constitutes an individual chrysotile filament. High resolution electron micrographs of chrysotile fibers in cross-section have shown both the multiple spiral pattern and the characteristic hollow center of this structure very clearly (8). The three known varieties of chrysotile are related to the manner in which these spirals form. Clino-chrysotile, the most common type, curves around the a axis of its monoclinic unit cell. In ortho-chrysotile, the unit cell is orthorhombic, but curvature remains around a. A rarer form, parachrysotile, also has an orthorhombic unit cell but is'curved about the b axis. Antigorite and lizardite must relieve the same strain, but they do so by quite different mechanisms: antigorite forms a "wavy" sheet structure with a very long unit cell repeat, while lizardite generally contains other elements that sub stitute within the silicate or magnesium hydroxide layers in a manner that equalizes the lattice spucings. It is interesting to note that, although r.ho differences in morphology between the filament structure ot chrysotile and the piato-iih.o or lath-like habit of anti norite or lisardine ere conspicuous, the similarities in structure on the anemic scale make it relatively difficult to distinguish these serpentine minerals from each other by X-ray powder diffraction (2). 49977 03T8 -9- The characteristic morphology of chrysotile fibers can be observed with the transmission electron microscope, an impor tant aid in their identification. The interior cavity of a chrysotile fiber is usually visible and has an average inner diameter of S0-1C0A. However, a hollow center is not always seen (8), and amorphous material may be observed within the interior of the filaments (2). Outer diameters of chrysotile fibers range from 150 to 1000A. The mean diameter is about 340A in the industrial samples we have examined, but other reports (2,8) cite mean diameters from 250 to 500A. The narrowness of its individual filaments gives rise to one of the most important physical properties of chrysotile asbestos, namely, its ve^y high specific surface area which can be in excess of 10 m /g. Fibers of the amphibole varieties of asbestos are considerably larger in cross-section (9). The ratio of length to diameter, known as the aspect ratio, may be quite large for individual chrysotile fibrils. Aspect ratios of several hundred are normal for most vein materials, but very short fibers with aspect ratios of 5 to 10 may be found in the serpentinite matrix of many ore bodies (2). Mean aspect ratios in samples related to the chlor-alkali process range from about 30 to over 400, corresponding to average, lengths up to about 15 microns. Obviously, any processing which tends to shear or grind the asbestos will both increase the number of fibers and decrease their aspect ratio. Chrysotile may occur either as individual fibrils or as bundles of fibrils. Since the diameters of single chrysotile filaments are only a fraction of the wave length of visible light, in dividual fibers cannot be resolved visually, even with the best optical microscope. The measurement of chrysotile by optical methods is therefore confined to material which may occur as bundles 'or other filamentary masses. The electron microscope is by far the most useful instrument for identification and quantification of individual chrysotile fibers. With an instrument equipped with accessories for selected area electron diffraction and energy dispersive X-ray spectroscopy, the morphological data can be supplemented with the diffraction pattern and quantitative elemental identification applied to individual particles. When somewhat larger quantities are involved, a successful analytical technique--atomic absorption spectroscopy (10), infrared spectroscopy (11), X-ray diffraction (12), differential thermal analysis (6), optical microscopy/index of refraction (3)--can be devised by exploiting some of the characteristic chemical and physical properties discussed .above. 409677 0319 -3- REFERENCES (1) P. B. Meijer and W. E. DeKoning-Pierens, TNO Nieuv/s 27, 661 (1972) (Eng.). (2) F. A. Mumpton, Siemens Review XLI, 75 (19 75) . (3) W. C. McCrone and I. M. Stewart, American Laboratory 6_ (4) , 13 (1974); Y. Julian and W. C. McCrone, The Microscope 1, 1 (1970). (4) E. J. W. Whittaker and F. J. Wicks, Amer. Mineral. 55_, 1025 (1970) . (5) M. S. Badollet, Can. Mining Met. Bull. No. 468, 237 (1951).- (6) J. P. Schelz, Thermochimica Acta , 197 (1974). (7) L. A. Drobyshev and Ya. Ya. Govorova, Kristallografiya 16, 544 (1971) (Russ.). (8) K. Yada, Acta Cryst. 23, 704 (1967) . (9) D. V. Rosato, "Asbestos, Its Industrial Applications." Reinhold Publishing Corp., New York, 1959, p. 43. (10) R. G. Keenan and J. R. Lynch, Amer. Ind. Hyg. Ass., J. 31, 587 (1970). (11) (12) J. A. Gadsden, J. Parker, and W. L. Smith, Atmos. Environ. A, 667 (1970). K. Goodhead and R. W. Martindale, Analyst (London) 94, 985 (1969). 409677 0320 * I DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE PUBLIC HEALTH SERVICE CENTER rOR DISEASE CONTROL ' August 8, 1975 NATIONAL INSTITU1 K FOD OCCUPAFIONAI SAFETY AND HEALTH 5600 FISHERS LANE ROCKVILLE. MARYLANO 20852 -i ii i j-tcrcx Dear Colleague: This communication is intended to alert you to recently gathered informa tion indicating a potential health hazard for persons exposed to asbestos during the servicing of motor vehicle brake and clutch assemblies. On July 21, 1975, the National Institite for Occupational Safety and Health convened a meeting of government and university scientists, industry representatives, and labor union officials to discuss the present state of knowledge with respect to this problem. Data was presented by investigators from the Mount Slanl School of Medicine in New York City indicating that workers engaged in the maintenance and repair of automobile and truck brake linings are exposed to potentially hazardous levels of airborne asbestos dust. Specific brake servicing operations studied included blow-out of automobile drum brake assemblies, grinding of used truck brake linings, and bevelling of new truck brake linings. Average peak asbestos air concentra tions for these three activities based on personal samples taken within ten feet of the operator were, respectively, 10.5, 3.75, and 37.3 fibers (>5 microns in length) per ml. An analysis of samples of brake drum dust revealed that almost all of the asbestos fibers found were shorter than 0.4 microns in length. Previous studies of the extent of asbestos emissions from automobile brake lining wear showed that only a very small fraction of the original asbestos content of the brake lining is found in brake drum dust (Ref. 1-3). It was presumed that this is due to thermal degradation of the fibers during braking. The present findings Indicate that enough asbestos is preserved to produce significant exposures during certain brake servicing procedures. The full extent of asbestos-related disease in brake servicing personnel is not known at present because this particular occupational group has not been studied systematically up to now. However, a review of the scientific literature on the association between asbestos exposure and mesothelial tumors of the pleura and peritoneum has revealed at least four cases of these rare tumors in persons who were employed in jobs involving automobile brake servicing (Ref. 4-6). 409677 0321 --7yr^tr.i Page 2 For your information and guidance, we are enclosing pertinent references, estimates of the population at risk, a NIOSH interim recommendation for brake and clutch servicing procedures, and a copy of the Department of Labor standard covering exposure to asbestos in the work place. The environmental studies of brake lining servicing operations outlined above together with observations of mesothellal tumors in persons so employed affirms the necessity for Instituting and maintaining recommended control measures in this industry so that the health hazards of asbestos are minimized. Enclosures Surveillance and Biometrics i S3 409677 0322 REFERENCES Lynch, J.R.: Brake Lining Decomposition Products. J Air Pollution Control Assoc, 18:824-26, 1968 Hickish, D.E. and Knight, K.L.: Exposure to Asbestos During Brake Maintenance. Ann Occup Hyg, 13:17-21, 1970 Jacko, M.G. and DuCharme, R.T.: Brake Emissions: Emission Measure ments from Brake and Clutch Linings from Selected Sources. EPA Report 68-04-0020, 1973 Newhouse, M.L. and Thompson, H.: Mesothelioma of Pleura and Peritoneum Following Exposure to Asbestos in the London Area. Brit J Ind Med, 22:261-69, 1965 McDonald, A.D. et al.: Epidemiology of Primary Malignant Mesothellal Tumors in Canada. Cancer, 26:914-19, 1970 Greenberg, M. and Lloyd Davies, T.A.: Mesothelioma Register 19671968. Brit J Ind Med, 31:91-104, 1974 409677 0323 ESTIMATES OF THE WORKFORCE POTENTIALLY EXPOSED TO ASBESTOS IN THE MANUFACTURING AND SERVICING OF BRAKE LININGS AND CLUTCHES Auto Mechanics Garage Workers Manufacture (original and rebuilding) TOTAL 833,535 67,679 6.657 907,871 SOURCE: Adapted from 1972 Census of Manufacturers, 1972 County Business Patterns, and Census of Population: 1970 Occupation by Industry (all are Department of Commerce, Census Bureau publications) 409677 0324 RECOMMENDED (INTERIM) PROCEDURES FOR ASBESTOS BRAKE AND CLUTCH SERVICING The National Institute for Occupational Safety and Health (NIOSH) has research underway concerning dust exposures during brake and clutch servicing. Due to preliminary data demonstrating significant asbestos exposures during presently used brake and clutch servicing techniques, NIOSH has reviewed alternate techniques whereby asbestos exposures are reduced. The following are interim procedures recommended by NIOSH to minimize dust exposures. 1. If possible, an area shall be designated for all brake and clutch repairs. Entrances into this area shall be posted with an asbestos exposure warning sign as follows: ^ Asbestos Dust Hazard Avoid Breathing Dust Wear Assigned Protective Equipment Do Not Remain in Area Unless Your Work Requires It Breathing Asbestos Dust May Cause Asbestosis and Cancer 2. During brake servicing, an air purifying respirator, either single use or with replaceable particulate filter(s), as approved by the Mining Enforcement and Safety Administration (formerly Bureau of Mines) or NIOSH, shall be worn during all procedures starting with the removal of the wheels and including reassembly. During manual clutch servicing, such a respirator shall be worn during removal and cleaning of the clutch, pressure plate and housing assembly and during instal lation of the new clutch assembly. 3. Dust shall first be cleaned from brake drums, brake backing plates, brake assemblies and clutch assemblies using an industrial type vacuum cleaner equipped with a high efficiency filter system (>99% efficiency for 0.3 pm diameter aerosols). After vacuum cleaning, any remaining dust shall be removed using a rag soaked in water and wrung until nearly dry. Under no circumstances shall compressed air or dry brushing be used for cleaning. 4. During arcing and riveting operations, an approved respirator, as described in (2) above, shall be worn. Grinding (arcing) machines shall be provided with local exhaust ventilation such that worker exposures are maintained at least below the 1976 OSHA asbestos standard (29 CFR 1910.1001).* At a minimum, the dust bag of the arcing machine shall be removed and replaced with the hose of the high efficiency industrial vacuum described in (3) above. 409677 0325 i{ i j ---'-'j j - 'i ; ii I: J 2- - 5. Industrial vacuum cleaner bags containing asbestos dust and cloths used for wiping brake and clutch assemblies shall be sealed in plastic bags and labeled with the following warning label printed in letters of sufficient size and contrast to be readily visible and legible: Caution Contains Asbestos Fibers Avoid Breathing Dust Breathing Asbestos Dust May Cause Asbestosis and Cancer ^ All asbestos waste shall be disposed of in accordance with the OSHA asbestos regulation, 29 CFR 1910.1001(h). During removal of vacuum bags, an approved respirator, as described in (2) above, shall be worn. 6. All floor cleaning in areas where brakes and clutches are repaired shall be done with the high efficiency industrial vacuum cleaner as described in (3) above. Grinding (arcing) machines shall also be cleaned with such a vacuum cleaner and .any remaining dust wiped with a damp cloth. An approved respirator, as described in (2) above, shall be used during this cleaning. 7. Although adherence to the above procedures should minimize any contamination of work clothing, it is required that the appropriate portions of the OSHA regulations on asbestos (29 CFR 1910.1001(d) (3 and 4)) concerning special clothing, change rooms, etc. be followed. NOTE: Strict adherence to the above procedures should minimize exposures to mechanics during brake and clutch servicing. These are interim recom mendations and are subject to revision pending results of ongoing NIOSH research. * Section 1910.1001 of the Code of Federal Regulations was formerly Section 1910.93a. This change was noted in the Federal Register, May 28, 1975. Prepared By Division of Field Studies and Clinical Investigations National Institute for Occupational Safety and Health Cincinnati, Ohio 409677 0326 --'--- UiU I -^ar.rjSB RULES ANB REGULATIONS iT->n air, as determined by the method pre scribed in paragraph (e> of this section. (c> Methods o/ compliance--(1) En gineering methods. (1) Engineering con trols. itngfnnartng controls, such as. but not limited to, isolation, enclosure, ex haust ventilation, and dust collection, shall be used to meet the exposure limits prescribed In paragraph (b) of this section. (11) Local exhaust ventilation. (a) Local exhaust ventilation and dust col lection systems shall be designed, con structed, installed, and maintained in accordance with the American National Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, ANSI Z9.2-1971, which is in corporated by reference herein. ' (b) See { 1910.6 concerning the avail ability of ANSI Z9.2-1971. and the maintenance of a historic file in connec tion therewith. The address of the Amer ican National Standards Institute is given in i 1910.100. (Hi) Particular tools. All hand-op erated and power-operated tools which may produce or release asbestos fibers in exoees of the exposure limits pre scribed in paragraph (b> of this section,. such as. but not limited to, saws, scorers, abrasive wheels, and drills, shtfll be pro vided with local exhaust ventflattoh sys tems tnaccordance with subdivision (li> of this subparagraph. at Work practices--(1) Wet methods. Insofar as practicable, asbestos shall be handled, mixed, applied, removed, cut, scored, or otherwise worked in- a wet state sofBcient to prevent the emission of airborne fibers in excess of the ex posure limits prescribed in paragraph (b) at this section, unless the usefulness of the product would be diminished 1919.93* Asbestos. thereby. (U) Particular products and opera tions. No asbestos cement, mortar, coat (a) Definitions. For the purpose of ing, grout, plaster, or similar material this section, (1) "Asbestos" Includes containing asbestos shall be removed chrysoUle. amosfte, croddollte, tremo- from bags, cartons, or other containers Ute. anthophylllte, end acdnnllte. in which they are shipped, without being (2) "Asbestos fibers" means asbestos fibers longer than S micrometers. <b) Permissible exposure to airborne concentrations of asbestos fibers--(O Standard effective July 7. 1972. The 8-hour time-weighted average airborne concentrations of asbestos fibers to which any employee may be exposed shall not exceed five fibers, longer than 5 micrometers, per cubic centimeter of air, as determined by the method pre scribed in paragraph (e) of this section. (21 Standard effective July 1, 1979. The 8-hour time-weighted average air-' borne concentrations of asbestos fibers to which any employee may be exposed shall not exceed two fibers, longer tfaaq S micrometers', per cubic centimeter at . either wetted, or enclosed, or ventilated so as to prevent effectively the release of airborne asbestos fibers in excess of the limits prescribed in paragraph (b) of this section. (iff) Spraying, demolition, or removed. Employees engaged in the spraying of asbestos, the removal, or demolition of pipes, structures, or equipment covered or tiaafiated with asbestos, and in the removal or demolition of asbestos in sulation or coverings shall be provided with respiratory equipment in accord ance with paragraph (d> (2) (ill) of this section and with special clothing in ac cordance with paragraph (d) (3) of this section. (d) Personal protective equipment-- (1) Compliance with the exposure limits air, as determined by the method pre prescribed by paragraph (b) of this sec scribed in paragraph (e) of this section. tion may not be achieved by the use of (3) Ceiling concentration. No em ployee shall be exposed at any time to airborne concentrations of . asbestos fibers In excess of 10 fibers, longer than 5 micrometers, per cubic centimeter of respirators or shift rotation of em ployees, except: (1) During the time period necessary to install the engineering controls and to institute the work practices required by paragraph (c) of this section; KDUAl REGISTER, VOl. 3, NO.-125--THURSDAY, JUNE 27, 1*74 409677 0327 .ii - ;| 9Mjf\e&*zCni*f&ijLCt jh&SS ilfZrt-, >:.:, I1 RULES AND REGULATIONS (il) In work situations In which the <ci Mo employee shall be assigned to (2) Personal monitoring--(1) Sam methods prescribed In paragraph (c) of tasks requiring the use of respirator: If, ples shall be collected from within the this section are either technically not based upon his most recent examination, breathing zone of the employees, on feasible or feasible to an extent insuffi an examining physician determines that membrane filters of 0.8 micrometer po cient to reduce the airborne concentra the employee will be unable to function rosity mounted in an open-face filter tions of asbestos fibers below the limits normally wearing a respirator, or that holder. Samples shall be taken for the prescribed by paragraph (b) of this the safety or health of the employee or determination of the 8-hour time- section: or other employees will be Impaired by his- weighted average airborne concentra (111) In emergencies. use of a respirator. Such employee shall tions and of the celling concentrations of (lv) Where both respirators and per be rotated to another Job or given the asbestos fibers. sonnel rotation are allowed by subdivi opportunity to transfer to a different po (U) Sampling frequency and patterns. sions (1), (U), or (111) of this subpara sition whose duties he Is able to perform After the Initial determinations required graph, and both are practicable, person with the same employer, in the same geo by subparagraph (1) of this paragraph, nel rotation shall be preferred and used. graphical area and with the same senior samples shall be of such frequency and (2) Where a respirator Is permitted by subparagraph (1) of this paragraph. It shall be selected from among those ap proved by the Bureau of Mines, Depart ment of the Interior, or the-National In stitute for Occupational Safety and Health, Department of Health, Educa tion, and Welfare, under the provisions of 30 CFR Part 11 (37 F.R. 6244, Mar. 25, 1972), and shall be used in accordance with subdivisions (1), (11), (111), and (lv) of this subparagraph. (I) Air purifying respirators. A reusa ble or single use air purifying respirator, or a respirator described in subdivision (U) or (ill) of this subparagraph, shall be used to reduce the concentrations of airborne asbestos fibers In the respirator below the exposure limits prescribed In paragraph (b) of this section, when the celling or the 8-hour time-weighted aver age airborne concentrations of asbestos fibers are reasonably expected to exceed no more than 10 times those limits. . (II) . Powered air purifying respirators. A full facepiece powered air purifying respirator, or a powered air purifying respirator, or a respirator described In subdivision (111) of this subparagraph, shall be used to reduce the concentra tions of airborne asbestos fibers in the respirator below the exposure limits pre scribed in paragraph (b) of this section, when the ceiling or the 8-hour timeweighted average concentrations of asbestos fibers are reasonably expected to exceed 10 times, but not 100 times, those limits. (III) Type "C" supplied-air respirators, continuous flow or pressure-demand class. A type "C" continuous flow or pres sure-demand, supplled-alr respirator shall be used to reduce the concentra tions of airborne asbestos fibers in the respirator below the exposure limits pre scribed In paragraph (b> of this section, when the celling or the 8-hour timeweighted average airborne concentra tions of asbestos fibers are reasonably expected to exceed 100 times those limits. (lv) Establishment of a respirator pro gram. (a) The employer shall establish a respirator program In accordance with the requirements of the American Na tional Standards Practices for Respira tory Protection, ANSI Z88J2-I0S9, which Is Incorporated by reference herein. ity, status, and rate of pay he had lust prior to such transfer, if such a different position is available. (3) Special clothing: The employer shall provide, and require the use of, spe cial clothing, such as coveralls or similar whole body clothing, head coverings, gloves, and foot coverings for any em ployee exposed to airborne concentra tions of asbestos fibers, which exceed the celling level prescribed hi paragraph (b> of this section. (4) Change rooms: (1) At any fixed place of employment exposed to airborne concentrations of asbestos fibers in ex cess of the exposure limits prescribed In paragraph (b) of this section, the em ployer shall provide change rooms for employees working regularly at the place. (11) Clothes lockers: The employer shall provide two separate lockers or con tainers for each employee, so separated or isolated as to prevent contamination of the employee's street clothes from his work clothes. (ill) Laundering: (a) Laundering of asbestos contaminated clothing shall be done so as to prevent the release of air borne asbestos fibers In excess of the ex posure limits prescribed In paragraph (b) of this section. (b) Any employer who gives asbestoscontaminated clothing to another person for laundering shall inform such person of the requirement in (a) of this subdi vision to effectively prevent the release of airborne asbestos fibers In excess of the exposure limits prescribed In para graph (b) of this section. (c) Contaminated clothing shall be transported in sealed Impermeable bags, or other closed, impermeable containers, and labeled in accordance with para graph (g) of this section. (e) Method of measurement. All de terminations of airborne concentrations of asbestos fibers shall be made by the membrane filter method at 400-450 X (magnification) <4 millimeter objective) with phase contrast Illumination. (f) Monitoring--Cl) Initial determi nations. Within 6 months of the publi cation of this section, every employer shall cause every place of employment where asbestos fibers are released to be monitored In such a way as to determine whether every employee's exposure to pattern as to represent with reasonable accuracy the levels of exposure of em ployees. In no case shall the sampling be done at Intervals greater than 6 months for employees whose exposure to asbestos may reasonably be foreseen to exceed the limits prescribed by paragraph (b> of this section. (3) Environmental monitoring--(1) samples shall be collected from areas of a work environment which are represent ative of the airborne concentrations of asbestos fibers which may reach the breathing zone of employees. Samples shall be collected on a membrane filter of OA micrometer porosity mounted in an open-face filter holder. Samples shall be taken for the determination of the 8hour time-weighted average airborne concentrations and of the celling con centrations of asbestos fibers. - (ft) Sampling frequency and patterns. After the Initial determinations required by subparagraph (1) of this paragraph, samples shall be of such frequency and pattern as to represent with reasonable accuracy the levels of exposure of the employees. In no case shall sampling be at Intervals greater than 6 months for employees whose exposures to asbestos may reasonably be foreseen to exceed the exposure limits prescribed In para graph (b) of this section. (4) Employee observation of monitor ing. Affected employees, or their rep resentatives, shall be given a reasonable opportunity to observe any monitoring required by this paragraph and shall have access to the records thereof. (g) Caution signs and labels. (1) Cau tion signs. (1) Posting. Caution signs shall be provided and displayed at each location where airborne concentrations of asbestos fibers may be In excess of the exposure limits prescribed In paragraph (b) of this section. Signs shall be posted at ouch a distance from such a location no that an employee may read the signs and take necessary protective steps be fore entering the area marked by tbo signs. Signs shall be posted at all ap proaches to areas containing excessive concentrations of airborne asbestos fibers. <li) Sign, specifications. The warning sighs required by subdivision (1) of this subparagraph shall conform to the re quirements of 20" x 14" vortical format (b) See 91910.6 concerning the avail asbestos fibers Is below t.he limits pre signs specified in 91810.145(d)(4), and ability of ANSI Z88.2-1969 and the main tenance of an historic file In connection therewith. The address of the American National Standards Institute Is given In 9 1910.100. scribed In paragraph (b) of this sec tion. If the limits arc exceeded, the em ployer shall immediately undertake a compliance program in accordance with paragraph (c> of this section. to this subdivision. The signs shall dis play the following legend in the lower panel, with letter sizes and styles of a visibility at least equal to that specified in this subdivision. federal register, voi. a?, mo. tss--Thursday, june 27, 1974 409677 0328 RULES AND REGULATIONS 23545 Leftnd Notation paragraph, which Indicates the em Asbestos---------------------------- 1" Sans Bertf. ployee's own exposure to asbestos fibers. Dust Hazard Avoid Breathing Dust___ Wear Arraigned Protectlvo Gothic or Block. %" Sans Serif. Gothic or Block. Y," Gothic. Vi" Gothic. (3) Employee -notification. Any em ployee found to have been exposed at any time to airborne concentrations of asbes tos fibers in excess of the limits pre scribed in paragraph (b) of this section shall be notified In writing of the expo Equipment. sure as soon as practicable but not later Do Hot Remain In Axaa Vi" Gothic. than 5 days of the finding. The employee Unless Tour Work Re- shall also be timely notified of the cor quires It. Breathing Asbestos Dust Hay Be Bsasardoud To It point Gothic. rective action being taken. (J) Medical examinations--(1) Gen Tour Health. eral. The employer shall provide or make Spacing between lines shall be at least equal to the height of the upper of any two lines. (2) Caution labels--(1) Labeling. Cau tion labels shall be affixed to all rawmaterials; mixtures, scrap, waste, debris, and other products containing asbestos fibers, or to their containers, except that no label is required where asbestos fibers available at his cost, medical examina tions relative to exposure to asbestos re quired by this paragraph. (2) Preplacement. The employer shall provide or make available to each of his employees, within 30 calendar days fol lowing bl't first employment In an occupation exposed to airborne con centrations of asbestos fibers, a compre hensive medical examina tion, which shall have been modified by a bonding agent, include, as a minimum, a chest roent coating, binder, or other material so that genogram (posterior-anterior 14 x 17 during any reasonably foreseeable use, inches), n history to elicit symptom handling, storage, disposal, processing, or atology of respiratory disease, and transportation, no airborne concentra pulmonary function tests to include tions of asbestos fibers in excess of the forced vital capacity (FVC) and forced exposure limits prescribed in paragraph expiratory volume at 1 second (FEVi_). (b) of this section will bereleased. (3) Annual examinations. On or be (il> Label specifications. The caution labels required by subdivision (1) of this subparagraph shall be printed In letters of sufficient size and contrast as to be readily visible and legible. The label shall state: CiUXION Contains Asbestos Fibers fore January 31, 1973, and at least an nually thereafter, every employer shall provide, or make available, comprehen sive medical examinations to each of his employees engaged in occupations ex posed to airborne concentrations of as bestos fibers. Such annual examination shall Include, as a minimum, a chest roentgenogram (posterior-anterior 14 x Avoid Creating Dust 17 inches), a history to elicit symptom Breathing Asbestos Dust May Cause Serious Bodily Barm atology of respiratory disease, and pulmonary function tests to include (h) Housekeeping--(1) Cleaning. All external surfaces in any place of employ ment shall be maintained free of accu mulations of asbestos fibers if, with their dispersion, there would be an excessive' concentration. (2) Waste disposal. Asbestos waste, scrap, debris, bags, containers, equip ment, and asbestos-contaminated cloth ing, consigned for disposal, which may produce in any reasonably foreseeable use, handling, storage, processing, dis posal, or transportation airborne concen trations of asbestos fibers in excees of the exposure limits prescribed in paragraph (b) of this section shall be collected and disposed of In sealed Impermeable bags; forced vital capacity (FVC) and forced expiratory volume at 1 second (FEVU). (4) Termination of employment. The employer shall provide, or make avail able, within 30 calendar days before or after the termination of employment of any employee engaged in an occupation exposed to airborne concentrations of asbestos fibers, a comprehensive medical examination which shall Include, as a minimum, a chest roentgenogram (pos terior-anterior 14 x 17 Inches), a history to elicit symptomatology of respiratory disease, and pulmonary function tests to Include forced vital capacity (FVC) and forced expiratory volume at 1 second (FEVi.). or other closed, Impermeable containers. (5) Recent examinations. No medical (i) Recordkeeping--(1) Exposure rec examination Is required of any em ords. Every employer shall maintain rec ployee, If adequate records show that ords of any personal or environmental the employee has been examined in ac monitoring required by this section. Rec ords shall be maintained for a period of cordance with this paragraph within the post 1-yesx period. at least 3 years and shall be made avail (6) Medical records--(i) Mainte able upon request to the Assistan t Secre nance. Employers of employees examined tary of Labor for Occupational Safety pursuant to this paragraph shall cause and Health, the Director of the National to be maintained complete and accurate Institute for Occupational Safety and records of all such medical examina Health, and to authorized representa tions. Records shall be retained by tives of either. employers for at least. 20 years. (2) Employee access. Every employee (11) Access. The contents of. the rec- and former employee shall have reason-' orda csf the medical examinations able access to any record required to be required by this paragraph shall be made maintained by subparagraph (1) of this available, for Inspection and copying. to the Assistant Secretary of Labor for Occupational Safety and Health, the Director of NIOSH, to authorized physi cians abd medical consultants of either of them, and. upon the request of an em ployee or former employee, to his physi cian. Any physician who conducts a medical examination required by this paragraph shall furnish to the employer of the examined employee all the Infor mation specifically required by this paragraph, and any other madloal In formation related to occupational ex posure to asbestos fibers. __ 409677 0329 FEPERAL REGISTER, VOL X?, NO. 125--THURSDAY, JUNE 27, 1974