Document O1K4k9Y122zepJdRq11wpnbzv

FILE NAME: Talc (TALC) DATE: 1979 DOC#: TALC164 DOCUMENT DESCRIPTION: Book Chapter - Mortality and Morbidity Among Talc Miners and Millers in Italy l ? 7>* MORTALITY AND MORBIDITY AMONG TALC MINERS AND MILLERS IN ITALY G.F. Rubino, G. Scansetti, G. Piolatto Institute of Occupational Health of Turin University,C.T.O.,Via Zuretti, 29,Torino, Italy. G. Gay Ospedale Valdese, Pomaretto, Torino, Italy. T he mortality experience of workers engaged in mining and milling the Italian non-asbestiform talc of Val Chisone was previously described (Rubino et a/., 1976). In that paper we expressed some doubt as to whether we could be fully confident in the comparison with the agricultural neighbouring population we had chosen as a control. For this report, therefore, expected deaths were recalulated by using as a standard the deaths rates of the Italian Male Population. These rates are available since 1951. W e have examined mortality patterns for the observation period from 1946 through 1974 using for the first quinquennium the rates relevant to the year 1951. T h e '"man-years" method according to Case and Lea was used (C ase and Lea, 1955). The results of this further analysis are reported in Table 1. There Is In both miners and millers a significant excess of overall mortality, which in miners is mainly accounted for by respiratory diseases and within this category by pneumoconiosis. In millers there were 4 deaths from simple pneumoconiosis or with superimposed tuberculosis. In both groups a very low incidence of respiratory cancer was observed. TABLE 1. Miners and Millers - Observed and Expected Deaths During 1946 -1974. Miners Millers Number in study 1260 418 Cause of Death 0 E SMR 0 E SMR All causes Lung cancer 560 446.9 125' 8 172 47 193 164.4 117' 4 6.1 66 Non-malignant respiratory diseases 109 33.1 3292 18 12.4 145 Pneumoconiosis Tb associated with Pneumoconiosis Tb 58 - - 13 - - 23 11.6 198' 3 - - 1 - - 8 4.1 195 'P jp < < .0051 Treating observed number of death as a Poisson vanable. No expectation was assumed for pneumoconiosis ( n s n 358 RUBINO ETAL. The mortality among miners according to cumulative dust exposure is shown in T able 2. Environmental information regarding the mines and mills, the composition of the talc, and the methods for allocating individuals to exposure categories, were reported in the previous paper (Rubino et al., 1976). It should be stated, however, that all mention of dust counts in this paper represent respirable particles of 0.5 to 5.0 micrometers. From Table 2 it is evident that an increasing trend of pneumoconi osis and tuberculosis is associated with increasing exposure. At the highest level of exposure, which w as estimated to be more than 5,665 mppef/years, about 20% of total deaths were due to pneumoconiosis, complicated or not by tuberculosis. The relationship of mortality to the intensity of exposure is not consistent in millers (Table 3). The four observed cases of pneumoconiosis are quite uniformly distributed in the three exposure levels. Further investigations were carried out for these deaths among millers in order to confirm the certified diagnosis, and to assess any possible exposure to other dust not previously recognized. Additional data were provided by the National Institute for Insurance. The description of these cases is reported in Table 4. For cases no. 1 and no. 3, exposure to free silica in addition to talc was found. C ase no. 1 had also worked as a graphite miner for 9 years. Case no. 3 was qualified for pay rolls as a miller, but he had, at irregular intervals, also worked as talc miner helper. For case no. 4, no additional data were available, as no claim compensation was set up. Case no. 2, whose death was certified as due to silico-tuberculosis, was only exposed to talc milling. Chest-X-Ray film showed rounded opacities, which were classified, according to ILO -UICC Classification (1970), as r Vz, in lower pulmonary zones in addition to tuberculous sclerosis and calcifications. Histological examina tion of necropsy specimens showed the presence of nodules partly fibro-hyaline with central necrosis, similar to caseous necrosis (Figure 1). These nodules may hardly be considered as classical silicotic nodules. However, the origin not simply tuberculous is supported by the presence of several birefringent particles which were found the as well as within the fibrous thickening of the septa (Figure 2). Infrared analysis and X-ray-diffractograms of dust from digested lung demonstrated 8 5 -9 0 % of talc particles mixed with 10-15% quartz. In conclusion, the results of our study show a marked difference between miners' and millers' mortality, as regards the incidence of pneumoconiosis. The high frequency among miners is attributable to the high content of free silica in the air dust in the mines, which was measured to be as high as 18% in drilling operations (Rubino ef a/., 1976). Through our further investigations, evidence was provided on one case of pneumoconiosis with tuberculous association, following exposure to talc in a work room where free silica content in the air dust was less than 2%. This death occurred 2 9 years after first exposure, in a worker exposed to an estimated average dust concentration of 24 mppcf for 23 years. The role of the small amount of free silica, in addition to talc, in inducing such pulmonary fibrosis is still an open question. Moreover, superimposed tuberculosis may be implicated in the development of the fibrosis as it happens in Pulmonary Massive Fibrosis (James, 1954). However, on the basis of results of investigations by Kleinfeld et al. (1964) and Leophonte et al. (1976) the experimental study of rats by W agner ef al. (1977), and our present findings, the biological possibility of a pneumoconiosis produced by non-asbestiform talc with low silica content emerges, although clinical and histologi cal aspects may differ in the various studies. MOI < AL. ^ a. o. 553-5 R.-5 3 .5 - o S - i 5 0 5 g 5 6'E. MORTALITY AND MORBIDITY AMONG TALC MINERS TABLE 2. Miners - Observed and Expected Deaths by Cumulative Dust Exposure. Exposure (as mppcf-years) < 1700 Number in Study 303 Cause of Death 0 All causes 126 Lung cancer 2 Non-malignant respiratory diseases 15 Pneumoconiosis 3 Tb associated with Pneumoconiosis 0 Tb 4 'P < .05 2P < .01 E 107.7 3.9 8.3 - 2.6 SMR 0 117 183 51 1 181' 30 - 15 - 3 154 7 1700-5665 >5665 425 E 130.7 4.8 9.5 3.5 SMR 0 1402 251 21 5 3162 64 - 40 - 10 200 12 532 E 208.5 8.5 15.3 55 SMR 1202 59 4182 ~ 218' , {/s'(/L 359 k .v s ,,,,x ; . ' - <\rv\>.iM \\ V - \V s \ \ \ \ \ V * ;X 1\ ' r-rwfl & M r f -vv TABLE 3. Millers - Observed and Expected Deaths by Cumulative Dust Exposure Exposure (as mppcf-years) < 142 Numberm Study 129 Cause of Death 0 All causes 72 Lung cancer 3 Non-malignant Respiratory Diseases 8 Pneumoconiosis 1 Tb associated with Pneumoconiosis 0 Tb 3 P< 05 -P < .01 E 47 4 1 5 2.7 - - 1 1 SMR 0 152J 59 200 1 296' 6 - 2 - 0 273 4 142-424 >424 137 152 E 49.5 1.5 4.3 _ 1 1 SMR 0 119 62 67 0 140 4 - 0 - 1 364' 1 E 67 5 3.1 5.4 _ - 1.9 SMR 92 _ 74 _ 53 RUBINO ET AL. rr al. MORTALITY AND MORBIDITY AMONG TALC MINERS 361 FIGURE 1. A module partly fibrohyaline with central necrotic area (Hematoxylin and Eosm. x 17 5) FIGURE 2. Fibrous thickening of alveolar septa with several blrefnngent particles. (Hematoxylin and Eosin. Polanzed light. X40. 362 RUBINO ET AL. TABLE 4. Description of the Certified Cases of Pneumoconiosis Among Talc Millers Case Number Duration of exposure (yrs) Latent period (yrs) Cumulative dust exposure as talc worker (mppcf-years) Other Exposures to Dust 1 3 33 99 1 Free silica 2 23 29 552.5 None 3 12 38 365.8 Free silica Death certification Necropsy findings Chest-X-Rays : ILO (UICC) category Silicosis Fibrohyaline nodules. Tb-sclerosis q 2 /2 A - tb Silico-Tb Fibrohyaline nodules. Tb-sclerosis r 1/ 2-pl -tb Silicosis Interstitial fibrosis 0/0 4 11 41 351.0 No information available Silicosis Not available Not available In order to assess the exposure level at which pneumoconiosis may occur, we have undertaken a morbidity study on talc millers. This is a preliminary report based on radiographic changes. The persons under study were the 43 millers still working in the years 1 9 7 5 -1 9 7 6 , and qualified by not having other exposures to inorganic or organic dust. Frequency of radiological opacities was assessed according to the estimated cumulative dust exposure. Table 5 shows that radiographic changes of 1 /0 ILOUICC category, or above, appear after a cumulative exposure of more than 160 mppcf-years, with the observation of 2 cases, classified as 1/1 and 112, confined to the cumulative exposure of more than 320 mppcf-years. TABLE 5. Radiographic Changes Among Talc Millers According to Cumulative Dust Exposure. Cumulative Dust Exposure (as mppcf-years) -80 81-160 161-320 320 + Mean value of mppcf-years within each category 45.8 Mean duration of exposure (years) 7.5 Number in Study 8 Irregular or rounded opacities 0/0 8 0/1 0 1/0 0 1/1 0 1/2 0 More than 1/2 0 'ptype -s type 131 6 15.5 11 8 3 0 0 0 0 246 8 21.8 13 4 5 4 0 0 0 4180 28 7 It 2 4' 3 r 10 ETAL. tion nie )le ated ILO160 >d to 1 + MORTALITY ANO MORBIDITY AMONG TALC MINERS 363 Results of this radiological examination indicate that rounded and irregular opacities consistent with pneumoconiosis can be found among these talc millers after an average duration of exposure of about 22 years, at an average dust concentration of about 11 mppcf. During the period these workers were exposed, the content of free silica in air dust was approximately 1% or less. In conclusion, our findings show that no relationship has been found between Italian talc exposure and cancer, whereas pneumoconiosis may be observed. Based on the radiographic changes we have classified, signs definitely consis tent with pneumoconiosis (1/1 or more of rounded or irregular opacities) may be found after an exposure of more than 320 mppcf-years, which means a lifetime exposure to more than 8 mppcf (assuming a 40 year working life). Initial signs may appear after 160 mppcf-years, which means a lifetime expsure to more than 4 mppcf. It is suggested from this data that the current Threshold Limit Value does not prevent radiological signs of pneumoconiosis. REFERENCES Case, R A.M., Lea, A.G.: Mustard gas poisoning, chronic bronchitis and lung cancer. Brit. J. Prev. Soc. Med. 9 :62-72,1955. International Classification of Radiographs of Pneumoconiosis (Revised 1968). 1970, ILO, Geneva James, W R.L The relationship of tuberculosis to the developmentof massive pneumoconiosis in coal workers. Br. J. Tuberc. and Dis. Chest 4 8 :89-93,1954. Kleinfeld, M., Messite, J., Shapiro, J., Kooyman O and Swencicki, R.: Lung Function in Talc Workers Arch. Environ. Hlth. 9:559-566,1964. Leophonte, P., Fabre, J. and Pous, J , Albarede, J.L. and Delaude, A.: Les pneumoconioses par le talc. Archives des maladies professionnelles, de Medicine du Travail et de Scurit Sociale 6' 513-532, 1976. Rubino, G.F., Scansetti, G., Piolatto, G and Romano, C.: Mortality Study of Talc Miners and Millers. J. Occup Med. 18:186-193,1976 Wagner, J.C., Berry. G , Cooke, T.J., Hill, R.J., Pooley, F D. and Skidmore1Animal experiments with talc Inhaled Particles IV, Part II, pp. 647-654. Pergamon Press, Oxford, England, 1977 i n / j .? /7 ?/ < C O P Y R IG H T 1979 By TH E SOCIETY FOR O C C U PATIONAL AND ENVIRONMENTAL HEALTH. 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