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FILE NAME Talc TALC DATE 1973 DOC TALC107 DOCUMENT DESCRIPTION Journal Article - A Study of Workers Exposed to Asbestiform Minerals in Commercial Talc Manufacture ENVIRONMENTAL RESEARCH 6 132 1413 973 A Study of Workers Exposed to Asbestiform Minerals in Commercial Talc Manufacture M. KLEINFELD J. MESSITE AND A. M. LANGER New York State Department of Labor Division of Industrial New York New York 10013 and Hygiene Environmental Sciences Laboratory Mount Sinai School of Medicine New York New York 10029 Received April 10 1972 A clinical and environmental study was made of a group of 39 workers to commercial talc dust of which tremolite and exposed anthophyllite were the major fibrous components and the findings were compared with a control that in spite of a mean group The data showed exposure of 16.2 yr with a range of 11-22 only one of the workers exposed to commercial talc dust showed a chest with pneumoconiosis The only significant difference betrwoeeenntgetnaolcgrawmorkceonrssistaenndt control was in the number of people having dyspnea and its severity The authors considered both the element of smoking and the exposure to commercial talc as aggravating factors which accounted for the dyspnea The findings of the 39 workers mercial talc but the degree of exposure of the group of 35 was In the latter group there was a appreciably greater It is possible that significantly increased prevalence of pneumoconioses commercial tale containing tremolite and anthophyllite as major fibrous constituents may be less fibrogenic than chrysotile or amosite at the of dust exposure present in this study degrees as Studies of the biologic response to different types of asbestos indicate that inhalation of chrysotile and amphibole asbestos dusts in present in some industrial concentrations environments can produce pulmonary fibrosis 1 Disabling pneumoconiosis may occur after inhalation of an asbestos dust after an appreciable elapsed time from onset of Morris et al 2 in study have reportedextphoatsucrheryuspotitloe2p0ryoedaurcseodr lmeo ssrepl1 um5 o- nary fibrosis than amosite or crocidolite when comparable concentrations of these asbestos minerals were inhaled These investigators have attributed the lesser pathogenicity of chrysotile to the ability of the lungs to eliminate it rapidly than amosite or crocidolite Recent data on anthophyllite exposure m inodrie - hcaatses the fiber to be both a fibrogen 16 and a carcinogen 17 Meurman 3 suggested that pleural plaques and calcification seem to among people exposed to anthophyllite but whether oneocctuyrpemoorfe afsrbeeqsuteonstliys more pathogenic than another still remains to be established The due to the influences of fiber size other minerals and difficulty arises asbestos dusts 4 Vigliani 5 cites Selikoff cofactors present in the in having stated that differences fibrogenicity may exist even between different sources of the asbestos Experimentally observations in the same type of guinea pig lung by Holt Mills and Young 6 show no differences in the fibrogenic response to four of bestos namely chrysotile crocidolite amosite and types as- anthophyllite On the other 132 Copyright '1973 by Academic Press Inc. All rights of reproduction in any form reserved i wie HR Ree cT e etd OE eo Sila et ne Con oe V a Bt deen ils eile lee, mote ote adsl ot te Geb Meet wee lee COMMERCIAL TALC MANUFACTURE 133 hand Parazzi Pernis Secchi and Vigliani 7 have shown that crocidolite produces a more marked cytotoxic action on guinea pig macrophages than does chrysotile Schnitzer and Pundsack 8 in an earlier study observed that chrysotile fibers produce a marked hemolytic effect on suspension of washed sheep erythrocytes whereas crocidolite amosite tremolite and anthophyllite produced negligible hemolytic effects In a more recent study personal communication to A.M.L. the same authors found that the relative surface areas of chrysotile versus the amphibole group were among the major factors in determining whether or not the materials were potentially capable of producing hemolytic effects Although the various authors cited above have shown different responses to different types of asbestos their results do not justify drawing firm conclusions as to the relative pathogenicity of the different types of asbestos The present study deals with a group of 39 individuals who were exposed to commercial tale dust with tremolite and anthophyllite as its major fibrous component The purpose of the study was to a correlate the environmental exposure with the clinical and roentgenographic findings in order to obtain information on a response relationship among workers all of whom had relatively longterm occupational exposure to commercial talc and b obtain additional data on the composition and morphology of the commercial talc dusts MATERIALS AND METHODS All of the workers in the study group were exposed to commercial talc for 10 or more yr Each worker underwent a clinical evaluation which included a de- tailed occupational history a physical examination and chest roentgenogram A similar evaluation was made of 41 workers who lived in the same area as the talc workers and who were of the same sex and mean age and range but who had had no occupational dust exposure in their working environment The 41 workers served as a control group Dyspnea was graded using a modification of Fletcher's criteria 9 Only four of the five grades categorized by Fletcher were adopted for this study The criteria for a positive smoking history was smoking of 20 or more cigarettes per day for a minimum of 5 yr In addition to the clinical and roentgenographic examinations air samples were taken in both the workers breathing zones and general air at various locations where the mining and milling of tremolite talc took place Total particle counts as well as fiber counts were determined The dust was collected by means of a midget impinger and the samples were taken at a rate of 0.1 cpm for 10 min according to the Public Health Service method 10 Several min samples were taken during the individuals work day to obtain results representative of a given worker's actual exposure Particles were counted using the light field power method The fibers were collected on a millipore filter and concentrations were determined using phase contrast illumination at 400 The mineral nature of 16 tale samples from New York State was determined These samples represented talc specimens obtained at different mining and milling operations as well as the finished product Techniques of analysis included polarized light microscopy transmission electron microscopy with selected area diffraction ray diffraction and electron microprobe analysis 134 KLEINFELD MESSITE AND LANGER TABLE 1 CLINICAL AND ENVIRONMENTAL DATA OF EXPOSED AND CONTROL GROUP No. Age yr mean range Exposure yr mean range Radiologic findings compatible with pneumoconioses Clinical findings Cough Dyspnea Lung crepitations Clubbing Positive smoking history Study group 39 45.9 34-75 16.2 11-22 1 2.6 10 25.65 9 23.1 2 5.1 0 0.0 19 48.7 Control 41 48.8 32-71 0 0.0 0 0.0 0 0.0 5 12.2 3 7.3 3 7.3 0 0.0 19 46.3 P N.S. N.S. N.S. 0.05 N.S. N.S. N.S. FINDINGS Clinical A summary of the clinical and environmental data of the 39 indi- viduals in the study group as compared to the control group is shown in Table 1 Data showing the relationships of dyspnea and cough to age smoking and duration of exposure are given in Table 2. The characteristics for each grade are given in Table 2. Table 3 summarizes the mean dust concentrations obtained for specific years between 1954 and 1970. Fiber counts were made only in 1970 as shown in Table 3. Comparative environmental clinical and chest roentgeno- TABLE 2 RELATIONSHIPS OF DYSPNEA AND COUGH TO AGE SMOKING AND DURATION OF EXPOSURE IN THE STUDY GROUP Case number Age Years exposure Dyspnea grade Cough Smoking No. packs cigarettes / day Years 123+ 123+ 123+ 4 5 . 6 784 784 784 45 14 36 19 45 15 53 15 45 20 49 20 58 14 50 19 55 15 1 Productive +00 1 25 1 0 +00 1 Productive +00 1 Productiveb +++ 1 329 4 Productive +++ 2 329 1 0 +++ 2 Productive 0 1.5 18 4 Productive + 2 31 1 0 * 0 Four grades of dyspnea a modification of Fletcher's grading 7 were used Grade able to walk normally without breathlessness on the level but breathless on hurrying or climbing slight hills Grade able to keep on walking at own slower than average pace on the level Grade 3 forced to stop for breath when walking at own slow pace on the level and Grade breathless on slightest exertion such as washing or undressing ,Morning only SR fi ee Mem ee COMMERCIAL TALC MANUFACTURE 135 TABLE 3 ENVIRONMENTAL DATA OBTAINED AT VARIOUS MINE AND MILL OPERATIONS - 1954 Mean dust counts mppcf 1958 1963 1964 1969 1970 Fiber count fiber > 5 ...m 1970 Mine Drilling ~ Dragline loading Tramming & mucking Primary crushing ; . Hoist loading Mill Secondary crushing Grinding Wheeler mills Grinding Hardinge mills Bagging Palletizing Bulk loading Direct R.R. car loading of bags 450 57 57 2 26 23 . 12 23 8 15 13 000+ 18 14 4 25 15 5 40 109 13 7 10 22 11 25 22 48 25 140 14 03725 12 13 03725 11 19 03725 8 03725 40 8 03725 10 6 10 31 62 8 16 22 260 . 182 30332 30332 30332 30332 30332 * TABLE 4 DATA IN PRESENT PLANT COMPARED TO ANOTHER PLANT STUDIED PREVIOUSLY Present plant Comparative study plant study P Environmental data mppcf Mining Drilling Mucking Milling Crushing Milling Bagging R.R. car and truck load Workers examined Number in group Age yr mean range Exposure yi mean range Radiographic findings compatible with pneumoconioses Clinical findings Cough Dyspnea Lung crepitations Clubbing Smokers 6 20 8235 8235 8235 8235 39 45.9 34-75 16.2 11-22 1 2.6 10 25.6 10 25.6 2 5.1 0 19 48.7 182 31 117 60 106 77 35 49.1 29-67 17.4 11-22 12 34.3 10 40.0 22 62.9 8 22.9 7 20.0 23 65.7 The dust count data represent mean dust concentrations over 20 periods N.S. N.S. 0.01 N.S. 0.01 0.05 N.S. 136 KLEINFELD MESSITE AND LANGER TABLE 5 COMPARATIVE DUST COUNTS AND FIBER COUNTS IN THE TWO PLANTS : Present plant data Comparative plant data ~ obtained in 1970 obtained in 1969 Mine . Drilling Dragline loading Tramming & mucking Primary crushing Hoist loading Mill Secondary crushing Grinding Wheeler Grinding Hardinge Bagging Palletizing Bulk loading R.R. car and truck loading a - Not done Dust count mppcf Fiber count fibers ml Dust count mppcf Fiber count fibers > 5 ...m 7018 8 09211 g 7018 ... 09211 | 7018 ... 09211 ... 48 ... 09211 ... 14 ... 09211 | 13 19 112 55 21-12-170 84 8 21-12-170 ... 3 8 21-12-170 ...3 6 21-12-170 | 10 21-12-170 ... 1 ... 21-12-170 graphic data compiled from a previous study made 6 yr earlier in another talc mining and milling plant ne same regional area are shown in Table 4. Table 5 shows the comparative dust and fiber counts in the two plants the counts in the present plant study were taken in 1970 and those at the comparative plant were taken in 1969. A flow sheet of the mining and milling operations in the plant most recently studied is shown in Fig 1 Mineral analysis of talc samples Optical ray electron microscopic and electron microprobe examination of the talc samples taken from the plant studied most recently indicated that the true mineral talc as defined mineralogically is only one of many mineral components in the materials mined milled and sold as commercial talc and that it is present as either a major or minor component The asbestiform minerals tremolite and anthophyllite may constitute major fractions of commercial talc Figures 2 3 and 4 show the various constituents of the dust samples as viewed under plane polarized light Fig 2 and electron microscopy Figs 3 and 4 DISCUSSION > A correlation of the clinical and environmental findings noted in Table 1 shows that in spite of a mean exposure of 16.2 yr with a range of 11-22 only one individual showed a chest roentgenogram consistent with pneumoconiosis This oc- curred in a old individual who had a nonproductive cough Grade 1 dyspnea and who worked as a janitor for 11 yr Although the absence of positive roentgenographic shadows does not conclusively exclude the presence of pneumoconiosis 2, gihapebeater tlo, fooncn ots anmewanternsinuaraar ernie newt tebe Sart Ss eed TEER ia oatisin wan litibenets cise eects | nm mee td steele ' COMMERCIAL TALC MANUFACTURE 137 DRILLING MUCKING OR DRAGLINE LOADING TRAMMING PRIMARY CRUSHING HOIST LOADING Underground Above Ground SCREENING SECONDARY CRUSHING DRYING SCREENING GRINDING HARDINGE OR WHEELER I MILLS BAGGING PALLETIZING BULK LOADING RR CAR OR TRUCK LOADING RR CAR OR TRUCK LOADING- FIG 1 Flow chart of commercial talc mining and milling operations in the plant studied in the other individuals who had positive clinical findings it makes the presence of pneumoconiosis less likely Usually the criteria for asbestotic pneumoconiosis is a history of prolonged exposure coupled with positive roentgenographic shadows and a restrictive breathing disorder When the clinical data on the workers was compared with the control group Table 1 there was no appreciable difference in the presence of cough or lung crepitations the only difference being in the number of people with dyspnea and its severity In the control group there were three individuals who had dyspnea which was categorized as Grade 1 Of the nine individuals in the study group with dyspnea six showed Grade 1 one showed Grade 2 and two showed Grade 4. Of the two with Grade 4 dyspne one was a cardiac who had sustained a myocardial infarction and the other had pulmonary emphysema prior to his employment These two individuals were heavy smokers one having smoked two packs daily for over 20 yr and the other two packs daily for a period of 31 yr Hence the element of smoking must be included as an important etiologic factor Although the dyspnea in these two individuals was not primarily related to their occupational exposure it may very well have been that their prolonged exposure to the commercial talc dust acted as an additional causal element By and large as shown in Table 2 there was no good correlation between dyspnea and cough when related to age smoking habits and duration of exposure In order to obtain some information on the response relationship it was 138 KLEINFELD MESSITE AND LANGER Bot : at y wi wh * eh est od * % SPARS. Bite acme WES Sees Me. ae r GS SRE ee cia! a Baeratte ee ace oN ee aS, Oe By * ideess y q ca ve a 20 ...m...m " iy eo ee Meg cart PEE se We Soe, FIG 2. Talc samples as viewed in plane polarized light All magnifications are as shown in F Sample A a primary crushing area B drilling area C mill D talc N200L E talc N200 F talc N300 These samples represent materials from source to end- product In addition to the mineral species rock fragments were observed in the first three samples " possible to compare a group of 35 individuals of the plant studied earlier Table 4 who were of the same age and range and who had a similar mean duration of exposure as well as range but whose degree of exposure in terms of total particle counts was appreciably greater than those in the plant recently studied as shown in Tables 4 and 5. As would be expected the group exposed to higher dust concentrations and fiber counts showed a significantly increased prevalence sets EO aie estes Ginn eee ade Sate ee aw COMMERCIAL TALC MANUFACTURE 139 FIG 3. Amphibole fibers present in talc This sample was examined for amphibole fibers and electron diffraction patterns obtained on selected fibers 3A insert 3A The structural array is clearly different than that obtained on talc fibers 3B shows the presence of talc fibers TF amphibole fibers and fragments A and the presence of talc aggregate grains TA 3C shows a chrysotile C fibril and an amphibole A fiber admixed in the talc of positive chest roentgenographic findings consistent with pneumoconiosis as well as more positive clinical findings In both talc plants there was no correlation between the fiber count and mean dust counts indicating the desirability of utilizing both total particle concentra- 140 por = te KLEINFELD MESSITE AND LANGER - - oad lg FIG 4. Talc aggregate grains as viewed with transmission electron microscopy These grains are apparently intergrowths of true talc talc fibers serpentine minerals and after fragments and amphibole fibers and fragments A These grains appear to survive the milling operations as entities Particles making up the grain may range from several thousand to several hundred angstroms in size B My tion as well as fiber counts when one correlates the environmental and clinical data Table 3 shows the lack of correlation between the two indices in the present plant studied There is at present no conclusive data that it is the fiber per se which is solely responsible for producing both the fibrotic and malignant changes In addition the effect of periodic exposures of short duration to high concentrations of fibers and particles or peak concentrations needs further study and clari- ABR ndinatat i the * Sa^-os Sa^-os aie kco te aaitten RAP DMIEe Tati AS. DAN LANDOW a LAND LANO DOWW ims ue tmumfuun G2 Lente oe ate cee cA nee a COMMERCIAL TALC MANUFACTURE 141 fication One should therefore consider the particle concentration fiber count and their peak values in establishing threshold limit values Furthermore the nature of the samples analyzed indicates that fiber counts of aerosols may not provide a true picture of exposure to asbestiform minerals because the fiber counts include talc fibers but exclude many small asbestos fibers and aggre- gate fibers which may contain substantial amounts of asbestiform minerals Fig 4 Suzuki and Churg 11 have suggested that it is the submicroscopic fibers that are responsible for most of the biologic effects produced by asbestos Other investigators 6 12 have also pointed out that the fine dust particles below 1 ...min length may be just as damaging as dust containing both large and small particles In a recent paper by Murphy and associates 13 on workers exposed to chronic low concentrations of asbestos dust in ship construction wherein the as- bestos used was principally chrysotile and amosite the authors reported that they did not find any evidence of asbestosis in persons with less than ten years of cumulative exposure No information on peak exposures was given The periodic peak exposures may be the more important factor relating to the fibrogenic effect These authors however observed that there was a progressive increase in prevalence of asbestotic pneumoconiosis with the years of exposure thereafter In terms of time weighted averages Murphy and associates 13 found no asbestosis in men exposed less than 60 mppcf Although it is difficult to compare their work with the present study it does nevertheless appear that while an appreciable number of workers in the present study exceeded the 60 mppcf they did not show any evidence of pneumoconiosis as determined by the criteria of Murphy and associates It is possible that in terms of a fibro- genic response tremolite and anthophyllite are less pathogenic than chrysotile or amosite at the degrees and intensity of dust exposures present in this study In terms of the present findings the data are not sufficiently conclusive for carcinogenicity for it has been shown that the occurrence of malignancy requires a longer elapsed time from onset of exposure Since the start of its operations the longest exposure in the plant studied was only 22 yr and the occurrence of malignancy from commercial talcs containing tremolite and anthophyllite in addition to talc has not infrequently required a longer duration or a greater elapsed time from initial exposure as was shown in an earlier study 14 None of the insulation workers studied by Selikoff and Hammond 15 died from carcinom~ of the lung mesothelial tumors or asbestosis before 20 years had elapsed since first exposure To date no instances of malignancy have occurred in any of the workers exposed exclusively to commercial talc at the plant studied SUMMARY AND CONCLUSIONS A clinical and environmental study was made of a group of 39 workers exposed to commercial talc dust of which tremolite and anthophyllite were the major fibrous components The clinical findings were compared to those obtained from a control group The data showed that in spite of a mean exposure of 16.2 yr with a range of 11-22 only one of the workers exposed to commercial talc dust showed a chest roentgenogram consistent with pneumoconiosis When the clinical 142 KLEINFELD MESSITE AND LANGER data on the workers was compared with the control group the only significant difference was in the number of people having dyspnea and its severity Two individuals had severe dyspnea One of the two had a cardiac condition and the other had primary pulmonary disease prior to his employment Both were heavy smokers for over 20 yr The authors considered both the element of smoking and the exposure to commercial talc as aggravating factors which accounted for the dyspnea The findings of the 39 workers in the present study were compared to those obtained from 35 workers studied earlier in another tale plant Both groups had similar mean durations of exposure to commercial talc but the de- gree of exposure of the group of 35 was appreciably greater In the group previously studied there was a significantly increased prevalence of positive roentgenographic findings consistent with pneumoconioses as well as more positive clinical findings In the present study where the mean exposure was 16.2 yr with a range of 11-22 no instance of malignancy occurred in any of the workers ex- posed exclusively to commercial talc It is possible that commercial talc containing tremolite and anthophyllite as major fibrous constituents may be less fibrogenic than chrysotile or amosite at the degrees and duration of dust exposure present in this study fe ACKNOWLEDGMENT Dr. Langer wishes to acknowledge support under Career Scientist Award NIEHS 44812 REFERENCES 1. WHIPPLE H. E. Ed 132 Art 1 87 111 1965 Biological effects of asbestos Ann N. Y. Acad Sci 2. MORRIS T. G. ROBERTS W. H. SILVERTON R. E. SKIDMORE J. W. WAGNER J. C. AND Coo--" G. W. 1965 Comparison of dust retention in specific pathogen and standard rats In Inhaled Particles and Vapours C. N. Davies Ed Pergamon Press London 2 205 3. MEURMAN L. O. Res 2 30-46 1968 Pleural fibrocalcific plaques and asbestos exposure Environ 4. Asbestos The Need for and Feasibility of Air Pollution Controls Committee on Biologic Effects of Atmospheric Pollutants Division of Medical Sciences National Research Council National Academy of Sciences Washington D. C. 1971 3 5. VIGLIANI E. C. 1968 The fibrogenic response to asbestos Med Lavoro 59 401 410 6. HOLT P. F. MILLS J. AND YOUNG D. K. 1965 Experimental asbestosis with four types of fibers importance of small particles Ann N. Y. Acad Sci 132 87-97 7. PARAZZI E. PERNIS B. SECCHI G. C. AND VIGLIANI E. C. 1968 Studies on in vitro cytotoxicity of asbestos dusts Med Lavoro 59 561-576 8. SCHNITZER R. J. AND PUNDSACK F. L. 1-13 1970 Asbestos hemolysis Environ Res 3 9. Short Questionnaire on Respiratory Symptoms as approved by the Medical Research Council Committee on the Aetiology of Chronic Bronchitis Dr. C. M. Fletcher Chairman London 1960 10. American Conference of Governmental Industrial Hygienists 1962 Air sampling instruments Document 3-31 Cincinnati Ohio 1963 11. Suzuki Y. AND CHURG J. 1969 Amer J. Pathol 55 79 91 Structure and development of the asbestos body : 12. DAVIS J. M. G. 1965 microscope studies of asbestosis in man and animals Ann N. Acad Sci 132 98 111 13. MURPHY R. L. H. Jr. FERRIS B. G. JR BURGESS W. A. WORCESTER J. AND GAENSLER WILKO IKA Uk, Kites sada cc cvects ab and negecedtes pe ce Sut yo oun aenendest SRB ERCE Roe 2 Seiten OE Salo Blan conte Blnmtanty Ea oe COMMERCIAL TALC MANUFACTURE 143 E. A. 1971 Effects of low concentrations of asbestos New Eng J. Med 285 1271 1278 14. KLEINFELD M. MESSITE J. KOOYMAN O. AND ZAKI M. 1967 Mortality among tale miners and millers in New York State Arch Environ Health 14 663 667 15. SELIKOFF I. J. AND HAMMOND E. C. 1968 Community effects of nonoccupational environmental asbestos exposure Amer J. Publ Health 58 1658 1666 16. AHLMAN K. PARTANEN T. J. RINTALA E. AND WIIKERI M. 1972 Anthophyllite mining and milling as a cause of asbestosis In Conf Biol Effects Asbestos Lyon France 2 O6ct. 1972 Paper 25 17. MEURMAN L. O. KIVILUOTO R. AND HAKAMA M. 1972 Mortality and morbidity of employees of anthophyllite asbestos in mines of Finland In Conf Biol Effects Asbestos Lyon France 2 O6ct. 1972 Paper 31 +