Document 65pqaZdK0a85NN3dgGM0mK5g6

FILE NAME: Talc (TALC) DATE: 1979 DOC#: TALC020 DOCUMENT DESCRIPTION: Conference Presentation from Dusts & Disease Conference - Fibrous Mineral Content of Consumer TalcContaining Products 392 W AGNER ETAL. Timbrell, V., Skidmore, J.W., Hyett, A.W., Wagner, J.C.: Exposure chambers for inhalation experiments with standard reference samples of asbestos of the International Union against Cancer (UICC). J. aerosol. Sci,, 7:215-233,1970. Wagner, J.C., Berry, G., Cooke, T.J., Hill, R.J., Pooley, F.D., Skidmore, J.W.: Animal experiments with talc. In: Walton, W .H., ed,, Inhaled particles IV. Proceedings of an International Symposium organized by the British Occupational Hygiene Society, Edinburgh, 22-26 September, 1975, Part 2, pp 647-652. Oxford, Pergamon, 1977. Wagner, J.C., Berry, G., Skidmore, J.W., Timbrell, V.: The effects of the inhalation of asbestos In rats. Brit. J. Cancer, 29:252-269, 1974. Wagner, J.C., Berry, G., Timbrell, V.: Mesotheliomata in rats after inoculation with asbestos and other materials. Brit. J. Cancer. 2 8:1 7 3 -18 5 . 1973. FIBROUS MINERAL CONTENT OF CONSUMER TALC-CONTAINING PRODUCTS A. N. Rohl and A. M. Langer Environmental Sciences Laboratory, Mount Sinai School of Medicine, City University of New York, New York, New York 10029 INTRODUCTION Approximately 800,000 tons of raw talc are produced annually in the United States. Talc is used in a number of industries, for a variety of purposes, e.g., the manufacture of ceramics, paints, paper, rubber, roofing, insecticides, stucco, plast ics, textiles and soaps (Wells, 1978). Pulverized talc is also used, on a much smaller tonnage basis, as an ingredient in such consumer products as cosmetic talcums, paper mache and modeling compounds, in spackling, patching compounds and putties, in automotive and boat body repair fillers and caulking compounds. The uses of talc in food products include rice coating, peanut polishing, candy molding and salami dusting. It is also used as a filler and excipient for pharmaceutical pills, and for dusting contraceptive diaphragms. Undoubtedly, there are other uses of talc in consumer products which are not generally known. Each product carries with it a distinct and individual inhalation and/or ingestion potential of the mineral components. The present report will deal with our studies of four types of these products, specifically talcum powders, spackling and patching compounds, talc-coated rice, and modeling materials. We have studied talc in other types of consumer products, but these four categories represent the varietal range of applications. It was our purpose to examine these materials to determine the presence or absence of minerals with known or suspected disease potential, specifically the fibrous amphiboles, quartz, and the asbestos of mineral chrysotile. GEOLOGICAL OCCURRENCE OF TALC Tale rocks occur fairly commonly in nature, and are formed as the result of two important geological processes, i.e., the hydrothermal alteration of ultramafic rocks and the low grade thermal metamorphism of silica-rich dolomite, CaMg(C03)2. These metamorphic processes frequently result in the formation of an assemblage of co-existing minerals, principally hydrous magnesium silicates, but also hydrous calcium-magnesium-iron silicates. Some of these are the magnesium and calcium amphibole minerals, which include anthophyllite and tremolite; and the serpentine minerals, including chrysotile asbestos. Depending on the nature of the parent rock, varying amounts of mica minerals (e.g., chlorite), quartz and carbonates may also be found (Table 1). Although pure talc deposits exist, very frequently the mineralogically complex deposits are used to provide "talc" for both industrial and consumer products. The mineral talc is a layer-type sheet silicate with the empirical chemical The authors wish to acknowledge support in part by grant ES 00928 from The National Institute of 394 ROHL AND LANGER TA B LE 1. Minerals which are commonly found in talc deposits Mineral Ideal formula Carbonates Calcite Dolomite Magnesite CaCOo3 C aM g(C 03)2 MgC03 Amphiboles Tremolite Anthophyllite Ca2Mg5Si8022(OH)2 (F e M g )7Si80 22(O H )2 Serpentine Antigorite Chrysotile (uncommon) Lizardite (uncommon) Mg3Si20 5(O H )4 Mg3Si20 6(OH)4 M g3Si20 5(O H )4 Others Quartz Mica, e.g. Phlogopite Chlorite, e.g. Penninite Si02 K2(M g ,F e )6[Si6AI20 20](O H )4 (Mg,AI,Fe)t2[Si,AI)8020](O H )16 formula, Mg3Si40,0(OH)2. However, aluminum (Al) or titanium (Ti) may substitute for silicon (Si), and iron (Fe) manganese (Mn), nickel (Ni), chromium (Cr), cobalt (Co), etc., may substitute for magnesium. Trace metal contamination is comm on. One talc deposit in the eastern United States, containing up to 0.2% Ni and substantial amounts of Cr and Co, has been used as a source of consumer talcums for many years. The layers of talc are very weakly bound to one another, and this accounts for the ease with which it breaks into sheets or platy fragments. This excellent cleavage, combined with high surface area, softness and light color make talc important as both an industrial and consumer material. The geology and mineralogy of talc have been extensively reviewed elsewhere (Rohl and Langer, 1974; Rohl ef al., 1976). ANALYTICAL TECHNIQUES FOR IDENTIFICATION AND QUANTIFI CATION OF FIBROUS MINERALS IN TALC Techniques which have been successfully used for the analysis of mineral fibers in talc products include optical microscopy, x-ray diffractometry and electron D03m Instrumentation The use of polarized light optics has long been a standard technique for the dentification of minerals. By using immersion oils of known refractive indices, for sxample, the optical properties of unknown crystalline particles can be determined. However, there are a number of conditions which limit the usefulness of optical nicroscopy. The accurate determination of refractive indices is extremely difficult vhen applied to particles less than 1 /urn in diameter. The optical properties of ibrous minerals frequently obviates full characterization of their optical constants. In ;onsumer talc products, most of which are finely pulverized powders, the particle ASBESTIFO RM CONTENT OF TALC 395 identification very difficult, if not impossible. Large numbers of fibers may go unde tected when this technique is used exclusively (Stanley and Norwood, 1973). However, it may be useful in some cases, at least as a screening or preliminary technique. X-ray powder diffraction has been used in both the continuous scan and step-scan modes of operation for the identification and quantitation of fibrous minerals in talc (Rohl and Langer, 1974; Rohl et al., 1976; Stanley and Norwood, 1973). This can be achieved by comparison of dilutions of known minerals in a talc matrix with unknowns. Quantitative analysis using this technique requires (1) a talc standard or matrix completely free of contaminating minerals and pure standards of fibrous minerals for preparing talc-fiber dilution standards; (2) a prepara tion method which is both sensitive and reproducible; and (3) selection of diagnostic x-ray reflections for quantitative analysis of specific minerals. X-ray diffraction in the step-scan mode is used for quantitative determination of tremolite, chrysotile and anthophyllite in talc at levels as low as 0.1%, 0.25% and 2.0%, by weight, respec tively (Rohl and Langer, 1974; Rohl eta/., 1976). These minerals are often found as fine-grained and intimate components of talc rock, and they are of particular concern as constituents of consumer talc products because of their biological potential (Daymon, 1946; Dreessen, 1933; Dreessen and Dalla Valle, 1935; Kleinfeld and Messite, 1960; Kleinfeld eta/., 1955, 1967,1973; Mclaughlin eta!., 1949; Millman, 1947; Nora, 1946; Porro and Levine, 1946; Porro et al., 1942; Reichman, 1944; Schepers, 1965; Siegal etal., 1943). The major limitation of x-ray diffraction analysis is its inability to distinguish between different morphological habits of the same mineral. For example, short tremolite fragments and long fibers of asbestiform tre molite give virtually identical x-ray patterns. To distinguish between different habits or shapes of the same mineral, including asbestos minerals, requires microscopic techniques. Transmission electron microscopy, used in conjunction with selected area electron diffraction (SAED), provides the resolution capability to visualize all parti cles and, in many cases, to identify them. For example, at magnifications of about 25,000x, or greater, chrysotile fibers may be identified on the basis of their unique morphology. In some instances, the morphological similarities between fibrous talc and amphibole fibers may be close enough to preclude the unequivocal identifica tion of the latter on the basis of such characteristics as cleavage, diffraction contrast figures and aspect ratios. However, talc fibers can be easily distinguished from am phibole fibers on the basis of SAED patterns. CONSUMER PRODUCTS STUDIES Consumer Talcums and Powders In a paper published in 1976, we reported a mineral and chemical chacterization of 20 consumer talcums and powders obtained in New York city during the period 1971-1975 (Rohl et at., 1976). Where known, all were formulated prior to 1973. Of the twenty products, 10 contained either tremolite or anthophyllite or both. The proportions, determined by step-scan x-ray diffraction ranged from 0.1% to over 14%, by weight. No attempt was made to distinguish proportions of fibrous and non-fibrous morphological phases, although every sample contained fiber. Two contained detectable amounts of chrysotile. The presence of these 396 ROHLAND LANGER Ki FIG U RE 1. Electron photomicrograph of amphibole fibers in cosmetic talcum powder X25.000 ASBESTIFO RM CONTENT OF TALC - - . . , - 1- r , _ *. ' i j- 1 -. ' 397 P ' T - r 1 :; F IG U R E 2. Electron photomicrograph of amphibole fibers in cosmetic talcum powder. x52,000 398 ROHL AND LANGER Quartz was found in eight samples, with seven ranging from 2 to 5%, and one as high as 35%. Chemical determinations, including bulk chemistry and trace metals, were also made cn the twenty samples. Four samples showed systematically high levels of nickel, chromium and cobalt, with average values, in parts per million, of 890, 518, and 57, respectively. The mean concentrations of nickel, chromium and cobalt in the other 16 samples were 18,29, and less than 3, respectively. A study, by this laboratory, of cosmetic talcums purchased during the period 1975-1978 is in progress. Preliminary results suggest that fewer products contain fibrous minerals. Spackling and Patching Compounds Spackling and patching compounds consist of fine-grained powders or pre mixed pastes. The ingredients usually are plaster of paris, limestone, talc, clays, micas or some other type of pulverized rock filler. Chrysotile is added to some products to provide reinforcement, and to control shrinkage and cracking as it cures. Fibrous amphibole minerals are found in some products because they occur naturally in talc, carbonates and other raw materials. In a paper published in 1975, the mineral content of 15 consumer spackling compounds purchased during the period 1972 to early 1974 was reported (Rohl etal., 1975). Two products contained talc as major components, and one of these also contained about 4 to 6%, by weight, of tremolite. Chrysotile was found in three products, ranging from 5 to 10%, by weight. Another product consisted principally of anthophyllite (10-12%) and quartz. Quartz was found in nine products, in proportions ranging from 5 to 70%, by weight. Optical and electron microscopic analyses showed that the asbestos and other mineral fibers ranged in length from 0.25 to 8.0/j.m (Figure 3). Almost all were shorter than 5 /m in length, which is of respirable size, yet they were not detected by optical microscopy. The paper also reported the results of mineral analyses of 10 industrial taping compounds used in drywall building construction. Nine of ten contained chrysotile in about the same proportions (5-12%) as the consumer products. Air measurements made during mixing, sanding and clean-up of drywall taping showed that airborne concentrations of two fibers per milliliter of air, or more, were common. Electron microscopic analyses of the air samples showed that, for every fiber visible by light microscopy (x400 magnification), from 200 to 1,000 fibers could be seen at magnifications of x 25,000. In the follow-up to this study, during 1975, five different consumer spackling compounds were obtained and analyzed. Of the five, four had talc present as a major phase, and also contained tremolite or anthophyllite, ranging from 2 to 12% by weight. Chrysotile was also found in three of the five products in proportions ranging from 5 to 15% . The latter concentrations reflect chrysotile as an additive, not as a talc contaminant. Talc - Coated Rice The practice of coating short grain and medium grain rice has been common in the United States for over 50 years. Several explanations for this practice have been advanced. The principal reason given for coating rice is to give an appealing smooth and shiny luster to the product. Puerto Rican, Oriental and Hawaiian consumers reportedly show a decided preference for coated rice. It has also been claimed that coated rice better withstands insect and fungal infestation and maintains moisture stabilization. The U.S. Department of Agriculture statistics indicate that about 300 million ASBESTIFORM CONTENT OF TALC 399 FIG U R E 3. Electron photomicrograph of chrysotile fibers in consumer spackling compound. x52,000 ___ The fihom nm nl! lens than 5um in length. Other particles are plaster of Pans, talc and mica 400 ROHLAND LANGER that an additional 470 million pounds were distributed to the Territories and the State of Hawaii that year (Federal Register, 1977). The total of 700 million pounds of coated rice represents about one-third of the rice sold in the United States and its Territories annually. Approximately, one pound of talc is used for coating 100 pounds of milled rice. Two samples of talc powder which are used for the coating of rice, that is, raw powders, were obtained from rice dealers. Five samples of talc-coated rice were purchased from local grocery stores. Three duplicate purchases were made. Stand ard weights of rice samples were washed twice in known volumes of water. Prior to rinsing, the water used for washing the rice was passed through an absolute filter to remove any adventitous mineral contamination. After each rinse, the wash water was passed through a 0.4p.m membrane filter to remove insoluble material. The material retained was dried, weighed and ashed in nascent oxygen to remove organic substances, then reweighed. These residues and the two raw talc powders were prepared and step-scanned for diagnostic asbestos reflections by x-ray diffraction according to procedures described by Rohl et al., (1976). In addi tion, polarizing optical microscopy, transmission electron microscopy and micro probe techniques were used to verify and further characterize the minerals present. Quantitative analysis of talc coating showed that one of the two samples of talc powder contained tremolite on the order of 5% by weight. Three of the eight rice coating residues were also found to contain tremolite and anthophyllite, up to 6%, by weight, and averaging about 3%. Another rice residue contained about 20% of a fibrous amphibole mineral, with a chemical composition similar to glaucophane. In four samples amphiboles were not detected by x-ray diffraction. However, analyses by transmission electron microscopy and microprobe showed that three contained trace amounts of asbestiform amphibole minerals. Chrysotile was not detected in any samples. Eleven samples of short-grain rice were purchased by colleagues in various cities in the United Kingdom, where much of the rice is imported from Australia and Italy. The washings of these samples of rice were found to contain no talc. One sample coating was found to be calcium carbonate. Talc-containing Modeling Materials Arts and crafts or modeling materials consist of dry powders, often mixtures of plaster of paris or gypsum, or calcium carbonate, or talc with fibrous minerals including chrysotile, tremolite and anthophyllite. These powders are mixed with water, and then cast, or shaped, into figures. In the school year 1971-1972, The New York City Board of Education had purchased 50,000 packages of paper mache - type material, each package contain ing five pounds. The product, upon analysis, was found to contain about 50% chrysotile. As a result, use of the product was discontinued in New York City schools. The material which was subsequently submitted for it consisted of a mixture of plaster and talc, including 15% to 20% tremolite and anthophyllite. Thereafter this material was discontinued as well. Six other commerical samples of arts and crafts materials, some marketed specifically for grade-school children, were analyzed for their mineral content. Of the six, three contained talc, and also tremolite and chrysotile. The asbestos and 401 A S B ESTIFO R M C O N TEN T OF TALC FIG U R E 4. Electron Photomicrograph of asbestiform amphiboles in dry mix-type modeling compound. CONCLUSIONS: Some of the studied consumer products which contain talc have been found to I contain varying amounts of natural mineral contaminants, some of which have been j demonstrated to be biologically active in humans. These minerals include I chrysotile, anthophyllite, tremolite, and quartz. In addition, a number of trace metals 1 were detected in forms essentially unknown. It is therefore recommended that: J 1. The significance of these materials in consumer products be evaluated 1 on a systematic clinical or epidemiological basis. Heavy intermittent or J habitual use of these products with high levels of fibrous mineral fibers I may produce disease. For example, recognition of this possibility has led to ! efforts by the cosmetic talcum industry to reduce or eliminate contaminated products by changing their sources of raw materials; 2. A ir measurements taken during drywall construction suggest that using : consumer spackling and patching compounds during home repair work could expose members of entire households to high concentrations of dust. An assessment of the risk to consumers was made by the Consumer Product Safety Commission in proposing rules to regulate patching com pounds (Blejer and Arlon, 1973). It was calculated that, for a conservative yearly exposure of four six-hour days, the increased risk of death from respiratory cancer from even such a modest exposure.would be unaccept able; 3. W hile some investigators have proposed that the ingestion of fibercontaminated talc products may pose a hazard of increased neoplastic risk, especially of the gastro-intestinal tract (Hammond ef a/., 1965; Henderson eta!., 1975;M atsudoef a/., 1974; Merewether, 1930; Selikoff ef a/., 1967), this disease potential is presently unknown. Talc-coated rice frequently constitutes a staple of the diet of many Americans, and one kilogram per week of talc could be consumed by some individuals. Since several of the talc coatings analyzed contained up to 5% and 6% amphibole minerals, some individuals could ingest about 600 milligrams per week of these mineral contaminants. Approximately 9.4 grams of talc would be ingested at the same time. The coating of rice with talc should be reviewed with the aim of eliminating it, or substituting coatings that do not contain these suspect minerals; 4. The presence of unbound asbestos, fibrous, and quartz minerals of respirable size in arts and crafts materials, especially those used by children with their long life expectancy, represents in our view an unaccept able exposure. These should be eliminated from such products immed iately. Artists, artisans and hobbyists may also be exposed to these mate rials, as well as to similar dusts generated during sculpting of talc or steatite rock. These individuals should be made aware of hazards associated with such exposures, and should protect themselves accordingly. REFERENCES Blejer, H.P. and Alton, R.: Talc: A possible occupational and environmental carcinogen. Jour. Occup. Med. 75:92-97,1973. Daymon, H.: Latent silicosis and tuberculosis. Amer. Rev. Tuberculosis 53:5 5 4 -55 9 ,1 9 46 . Dreessen, W .C.: Effects o1 certain silicate dusts in the lungs. J. Indust. Hyg. 75:66.78, 1933. Dreessen, W .C. and Dalla Valle, J .M .: The effects of exposure to dust in two Georgia talc mills and mines: Publ. Health Rpts. 50:1405-1415, 1935. Federal Register: Proposal to Revise Standard for Enriched Rice by U.S. Food and Drug Administration. V 42, no. 136, July 15, 1977. Hammond, E.C., Selikoff, I.J. and Churg, J.: Neoplasia among insulation workers in the United States with special reference to intra-abdominal neoplasia. Annai. N.Y. Acad. Sci. 732:519-525, 1965. Henderson, W.J., Evans, D.M.D., Davies, J.D. and Griffiths, K.: Analysis of particles in stomach tumours from Japanese males. Envir. Research 9:240-249, 1975. Kleinfeld, M. and Messite, J.: Problem areas in pneumoconiosis. Arch. Environ. Health 5:428-437,1960. Kleinfeld, M., Messite, J., Kooyman. O. and Zaki, M.H.: Mortality among talc miners and millers in New York State. Arch. Env. Health 74:663-667, 1967. 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Porro, F.W., Patton, J.R. and Hobbs, A.A.: Pneumoconiosis in the talc industry. Am. J. Roentgenol. 47:507-524, 1942. Reichman, V.: Uber talkumstaublunge: Arch. f. Gewerbepath. and Gewerbehyg. 72:319-322,1944. Rohl, A.N. and Langer, A.M.: Identification and quantitation of asbestos in talc. Environ. Health Persp. 9:95-109,1974. Rohl, A.N. et at.: Consumer talcums and powders: Mineral and chemical characterization. J. Toxicology and Envir. Health 2:255-284, 1976. Rohl, A.N., Langer, A.M., Selikoff, I.J. and Nicholson, W.J.: Exposure to asbestos in the use of consumer spackling, patching and taping compounds. Science 789:551-553, 1975. Schepers, G .W .H .: Discussion of Newhouse, M.L. and Thompson, H.: Epidemiology of mesothelial tumors in the London area. Annals of N.Y. Acad, of Sci. 579-602,1965. Selikoff, I.J. eta/.: Asbestosis and neoplasia. Amer. Jour. Med. 42:487-496, 1967. Siegal, W., Smith, A.R. and Greenburg, L.: The dust hazard in tremolite talc mining, including roent genological findings in talc workers. Amer. J. Roentgenolog. 4:11-29,1943. Stanley, H.D. and Norwood, R .E .: The detection and identification of asbestos and asbestiform materials in talc. Report Pfizer, Inc., 1973. Wells, J.R.: Talc and pyrophyllite in 1976. Mineral tacts and problems. U.S. Bureau of Mines, Washing ton, D.C., U.S. Government Printing Office, 1978.