Document MM8qOgya3xLw2yNkMjDz2JGXM

FILE NAME: RT Vanderbilt (RTV) DATE: 1974 DOC#: RTV234 DOCUMENT DESCRIPTION: Journal Article - Talc Dust and its Toxicity  imlKm mv-A$\vm$t$ SP^1M1 ltepS;sapsl^8S#?i MM iB i ^ ftS i iiiHEp s s^sgaaHaagHmi MbnMhHMMHarigB^WnHis1 iB r SYNOPSIS Xale Dust and Its Toxicity Gyan S. Rajhans, Dust Control Specialist, Occupational Health Protection Branch, Ontario. Ministry of Health; Toronto, Ont. - Introduction The widespread use of `talc' and `talcum powder' in industry and by the public has elicited much interest in its toxicity in recent years. Talc dust has been re ported to cause pneumoconiosis, lung cancer, cancer of the pleura and gastrointestinal cancer. Although there is no general consensus regarding the various health effects of talc dust, it is universally agreed that the continued inhalation of significant amounts can pro duce a special kind of pneumoconiosis generally refer red to as talcosis. According to the medical experts, talcosis appears as a fine diffuse pulmonary fibrosis similar to asbestosis in appearance. Much of the difficulty in estab lishing a causal relationship between tale dust and various pulmonary changes is due to the fact that commercial talc usually contains a variety of silicates such as asbestos, tremolite and anthophyllite. and other ingredients such as quartz or free silica, which by themselves could produce severe pulmonary reac tion. Thus, there is a need to clarify the mineralogy from the occupational health standpoint. A search through the literature on talc pneumoconiosis reveals to the writer that the published studies of this disease are mostly case histories and have seldom made at tempts to separate the effects of the different mineral impurities in talc. The purpose of this report is to offer up-to-date knowledge on varieties of commercial talc currently used industry and the health hazards associated with it and its associated minerals. Toxicity The steatite variety of talc, when ground to a powder, appears as microscopic dumb-bell-shaped flakes, less than 75 micrometers in size. This powder is called talc dust. Talc particles smaller than 7 micro meters, when inhaled, are carried directly into the lungs, where their effect may produce a pulmonary disease called talcosis. However, as stated earlier, there is no such thing as pure steatite or asbestine or soapstone, because any commercial talc may contain a variety of accessory minerals. As a result, there is a great deal of contro versy and confusion as to which components of the talc are responsible for pneumoconiosis. Tremolite and anthophyllite impurities in dust are in the form of long fine needles with a thickness of about'0.8 micrometer and a length of 5-15 micrometers. Therefore, these fibres are mostly respirable and are considered to be capable of producing all those diseases which are usually associated with asbestos fibres; e.g. asbestosis, carcinoma of the lung and mesothelioma. Thorel'1' in 1896 described the first case of talc pneumoconiosis. Since then, several studies have been ' 1 , 1 '~ *, i ----- T' -. 'h /n n n m a q r J A f lT llt f i mines handling steatite talc with a 10% tremolite content. They found severe and disabling cases among the groups working at average dust concentrations of 135 to 300 mppef (million particles per cubic foot). A large number of studies have been done among the talc mine workers of New York State. Siegel et aZ.m In 19-13, published a chest X-ray survey of 221 talc miners. The survey disclosed pulmonary fibrosis in 32 workers, 18 of whom had had no other occupational dust exposure. This study was later followed up by Kieinfeld et at.'45 in 1954, and they found that the pneumoconiosis was progressive and disabling. In 1959, Messite et al.a) pointed out that workers exposed to both fibrous and non-fibrous varieties of talc suf fered from pulmonary fibrosis. A report on the clinical anti pathological findings in six patients, who had an average exposure to talc dust of 26 years with a range of 20 to 33 years, was reported by the same authors"" in 1963. The major clinical features were chronic pro ductive cough, dyspnea, diminished breath sounds, limited che3t expansion, diffuse rales and clubbing. In 1967. Kleinfeld et al.m published mortality data on 91 talc miners and: millers in .New York State who.had 15 or more years of exposure to talc dust by 1940 or had achieved 15 years between 1940 and 1965. Propor tional mortality from carcinoma of the lung and pleura among talc workers was four times that of the control population. The dust exposure consisted pre dominantly, of. talc mixed, with other silicates such as, serpentine and tremolite, carbonates and a small amount of free silica. The average dust counts between 1940 and 1965 varied from 5 to 1227 mppef. Schepers and Durkan'8' studied the intravenous and intratracheal effects of the different New York com mercial talc components (3 micrometers or less) in animals. Besides using individual minerals, they also carried out experiments with different ^mixtures of minerals. Their results indicate that talc is predomin antly cytogenetic, whereas tremolite and anthophyllite fibres markedly affected the degree of fibrosis -- the longer fibre being much more damaging in this respect. Animal experiments were also carried out by Lueehtratlrand Schmidt"' and Schulz and Williams.'10' They concluded that the fibrogenic activity of talc dusts was mainly due to impurities. The greatest amount of fibrous tissue was produced either by the samples containing talc-serpentine mixtures or tremolite with small quantities of serpentine and carbonate. This theory has been challenged by Kleinfeld et al. in a recent article'11' which reports on a clinical and envi ronmental study made of a group of 39 workers ex posed to tremolite- and anthophyllite-bearing talc. The data show that, in spite of a mean exposure of 16.2 years, only one of the workers exposed showed a chest roentgenogram consistent with pneumoconiosis. To date, only two studies have been made and re ported on workers exposed to talc dust in the rubber industry. The first study was conducted by Hogue and Mallite'12', who were unable to find any abnormal ities in workers exposed to talc dust used as a Miller et ai.'121 studied the lungs of a rubber worker who had had heavy exposure to talc dust from 1941 to 1950 and who died with cor pulmonale in 1962. The patient had progressive dyspnea and cachexia. How ever, the authors could not demonstrate the exact mineralogy of talc particles found in the lungs. Recently, a few articles have been published on the health hazards associated with cosmetic talcum powder. In 1968, C-ralley et aVw reported that talcum powder contained a significant amount of respirable fibres and was a potential source of the ferruginous bodies observed in the lungs of humans. It is, however, agreed by the authors that exposure in the use of cosmetic talcum products is very intermittent and much smaller than continuous industrial exposure. The only reported cutaneous reactions from the use of talcum powder involve talc granulomas, and these also have been rare.tI5'10> Merliss'171 suggested that the high incidence of gas tric cancer in Japan may be associated with the treat ment of rice with talc. He noted that some commercial talc contains asbestos, which he proposed as an etilogic agent in gastric cancer. This theory has recently been doubted by Smith'181, who carried out tests for carci nogenicity of various preparations of asbestos and talc, including the fibrous variety in 45 hamsters, and found no gastric or other tumours. . The, basic conclusion that one can derive from the - studies reported above is that, of all the varieties, the fibrous form of talc dust (tremolite and asbestine) is probably the most'hazardous. The granular variety (steatite), on the other hand, could produce symptom atic pneumoconiosis providing there is exposure to significant iereis. The signs and symptoms are those common to other pneumoconioses: e.g. diminished breath sounds, basilar crepitations, limited chest ex pansion, dyspnea and cough. Chronic bronchitis and emphysema are frequently associated with this disease. A ssessm ent of Health Hazards and T LV As there are basically two groups of talc, granular (noil-fibrous) and fibrous, it seems advisable to have two different sampling techniques and threshold limit values. Because commercial talc may contain a variety of accessory minerals which may or may not be de trimental to health, it is also advisable to analyse every sample of talc before a particular technique or threshold limit value (TLV) can be applied. The American Conference of Governmental Hygienists proposes a TLV of 20 mppcf for the granular variety and 5 fibres/ml greater than 5 micrometers in length (same as asbestos) for talc containing fibers. The TLV of 20 mppcf is based largely on the work of Dressen-and Dallavalle'21 and is determined from impinger samples. The technique of impinger counts has. been described in detail by the writer elsewhere.'1"1The TLV of 5 fibres/ml for talc containing fibres is deter mined because of the striking similarity in the fibrotic reaction produced by talc and asbestos, fibres.'8'141 The membrane filter technique used for fibre counts is described by Edwards and Lynch.'201 The Occupa tional Health Laboratory of the Ministry of Health has introduced several modifications to the technique. These modifications have been described in reference 19. Both the impinger and membrane filter techniques involve relatively short-time samplers unless the mem brane filter is attached to a personal sampler, Hence, -------------------- ----------- ----4-'U- ---- concentrations over an 8-hour period. It should be realized that the concentration of dust in the air to: which a worker is exposed varies depending on the nature of the operation, the type of work performed: by the operator and the position of the operator relative to the source of dust. Furthermore, the amount of dust inhaled by a worker can vary daily and season ally. In order to obtain representative samples of workers' exposures, it is necessary to collect samples under varying working conditions and then a com parison should be made with the TLVs. References (1) Thorel, C., Die Specksteinlunge, Beitr. Path. Anat., Vol. 20, p. 85, 1896. (2) Dressen, W. C., and J. M. Dallavalle, Effects of Exposure to Dust in Two Georgia Talc Mills and Mines, U.S. Pub. Health Report, Vol. 50, p. 131, 1935. (3) Siegal, W., A. R. Smith and L. Greenburg., The Dust Hazard in Tremolite Talc Mining, Including Roentgenological Findings in Talc Works, American Jour. Raentgenol., Vol. 49, pp. 11-29, 1943. (4) Kleinfeld, M., J. Messite and I. R. Tabershaw, Talc Pneumoconiosis, Arch, Environmental Health, Vol. 12, pp. 66-72, July 1955. (5) Messite, J., G. Reddin and M. Kleinfeld, Pulmonary Talcosis -- A Clinical and Environmental Study, Arch. Industrial Health, Vol. 20, pp. 408-413, 1959. (6) Kleinfeld, M., et al., Talc Pneumoconiosis -- A Re port of Six Patients with Post-Mortem Findings, Arch. Environmental Health, Vol. 7, pp. 101-115, July 1963. (7) Kleinfeld, M., J. Messite, Q. Kooyman and M, Zaki, Mortality Among Talc Miners and .Millers in N.Y. State, Arch. Environmental Health, Vol. 14, pp. 663667, May 1967. (8) Schepers, G. W. H,, and T. M. Durkan, "An Experi ments] Study of the Effects of Talc Dust and Animal Tissue, Trans. Mclntyre-Saranc Conf. on Occupa tional Chest Disease, Chicago, American Medical -i...Assoc., 1955. (9 ) Luechtrath, H., and K. G. Schmidt, On Talcum and Steatite -- Their Relations to Asbestos and Their Effects in Intratracheal. Animal Tests on Rats, Betr, Silikoseforsch, Vol. 61, pp. 1-60, 1959. (10) Schulz, R. Z., and C. R. Williams, Commercial Talc -- Animals and Mineralogical Studies, Jour. Indus trial Hygiene, Vol. 24, p. 75, 1942. (11) Kleinfeld, M., J. Messite and A. Longer, A Study of Workers Exposed to Asbestiform Minerals in Commercial Talc Manufacture, Environmental Re search, Vol. 6, pp. 132-143, 1973. (12) Hogue, W. L., Jr., and P. S. Mallete, A Study of Workers Exposed to Talc and Other Dusting Com pounds in the Rubber Industry, Jour. Industrial Hygiene & Toxicology, Vol. 31, p. 359, 1949. (13) Miller, A., N. E. Bades and R. A. Bade, Talc Pneu moconiosis Due to Sub-Light Microscopic Particles, Physiologic and Mineralogic Studies, Bull. American College Chest Physicians, Vol. 92, p. 24, 1970. (14) Cralley, L. J., M. M. Key, D. H. Groth, W. S. Lainhart and R. M. Ligo, Fibrous and Mineral Content of Cosmetic Talcum Products, American Industrial Hygiene Assoc. Jour., Vol. 29, pp. 350-364, July. : August 1968. ' (15) Lichtman, A. L., J. R. McDonald, C. P. Dixon and P. C. Mann, Talc Granuloma, Surg. Gynec. & Obst., Vol. 83, p. 531, 1946. (16) Tye, M. J., K. H. Ashimoto and F. Pox, Talc Granu lomas of the Skin, Jour. American Medical Assoc., Vol. 198, p. 1370, 1966. (17) Meriless, R. R., Talc-Treated Rice and Japanese Stomach Cancer, Science, Vol. 173, p. 1141, Sept. 17, 1971. (18) Smith, W. E., Industrial Hygiene Summary Reports, Asbestos, Talc and Nitrites in Relation to Gastric Cancer, A.I.H.A.J., Vol. 34-5, pp. 227-228, May 1973. (19) Rajhans, G. S., Fibrous Dust -- Its Measurement and Control, CIM Bulletin, Vol. 63, No. 700, pp. 900910, Aug. 1970. (20) Lynch, J. R., and H. E. Ayer, Measurement of Dust Exposure in the Asbestos Textile Industrv. American