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Query: UMLS:C0037116 (silicosis)
 1,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To estimate the quantitative relation between exposure to respirable silica dust and risk of an attack of silicosis, 1151 workers exposed to silica dust and employed from 1958 to 1987 in a tungsten mine in China were investigated. The results showed that the ratio of respirable silica dust concentration to total silica dust concentration was 0.529. Then, the total silica dust concentration in historical surveillance and monitoring data was converted to respirable silica dust concentration. The free silica content in respirable dust determined by x ray diffraction averaged 24.7%. Multiple logistic regression was used for the dichotomous dependent variables (presence or absence of silicosis). The independent variables in the multiple logistic regression with presence of silicosis as the dependent variable were age when first exposed, tuberculosis (presence or absence), and cumulative exposure to respirable silica dust. The partial regression coefficient of individual cumulative exposure was estimated as 0.079. It implied a positive association between exposure to respirable silica dust and risk of an attack of silicosis. The exposure limit for respirable silica dust was estimated as 0.24 mg/m3 under given conditions.
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PMID:Relation between exposure to respirable silica dust and silicosis in a tungsten mine in China. 131 Feb 54

As part of a larger study relating to silica exposure, silicosis, and lung cancer mortality in Chinese mine and factory workers, 1936 old posterior-anterior chest X-rays were re-interpreted according to the 1986 Chinese Roentgenodiagnostic Criteria of pneumoconioses. Each film was independently read by three individuals from a panel of eleven radiologists, and this reading was compared to the original one. Subsequent to the independent readings, a groups of three readers interpreted the films together, called the consensus readings. Comparisons were made by Chinese stage of pneumoconiosis. For the entire cohort, there was a crude agreement of 57.4% between the old and the new interpretations. Agreement within one step of full agreement was 92.5%. The interpretations done by median reading and by consensus were very similar. In general, there was a tendency for the old readings to be slightly higher compared to the new interpretations. This tendency was most marked in the tin mines, followed in decreasing order by the iron/copper mines, the potteries, and the tungsten mines. The agreement between the old and new interpretations is felt to be satisfactory.
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PMID:A comparison of radiographic interpretation of silica exposed workers using the 1963 and the 1986 Chinese roentgenodiagnostic criteria of pneumoconioses. 133 88

The association between silicosis and lung cancer mortality was estimated in 9,912 (369 silicotics and 9,543 nonsilicotics) white male metal miners. These miners were examined by the U.S. Public Health Service during 1959-1961 and were followed through 1975. Miners were excluded from this study if they were employed in a mine during 1959-1961 that used diesel equipment underground. The ores that were mined consisted of copper, lead-zinc, iron, mercury, lead silver, gold and gold-silver, tungsten, and molybenum. The standardized mortality ratio (SMR, U.S. white male rates) for lung cancer was 1.73 (95% CI: .94-2.90) in silicotics and 1.18 (95% CI: .98-1.42) in nonsilicotics. Additionally, SMRs were higher in silicotics than in nonsilicotics, even in most subgroups stratified by cigarette smoking habit, type of ore mined, years of service in an underground job, radon exposure group, or year of hire. When lung cancer mortality between silicotics and nonsilicotics was compared, the age-adjusted rate ratio (95% CI) was 1.56 (.91-2.68), and the age- and smoking-adjusted rate ratio was 1.96 (.98-3.67). Corresponding figures for miners who were employed in mines with low levels of radon exposure were 1.90 (.98-3.67) and 2.59 (1.44-4.68), respectively. These findings indicate that lung cancer mortality risk was increased in silicotics, and this probably did not result from chance or bias. However, confounding from radon exposure could not be ruled out. The findings indicate that further follow-up of this cohort is needed.
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PMID:Silicosis and lung cancer in U.S. metal miners. 200 98

An evaluation of the effects of dust prevention in the Jiangxi tungsten mines has been carried out. The rate of silicosis morbidity in most mines was under 1%. Up to 1983, the rate in individual mines is 1.95%. According to the data from those mines, the forecasting of cumulative probability of morbidity of mine workers having been in contact with dust for 30 years is up to 7.5%. From those data, the authors suggest that the maximum permissible concentration of dust should be 1.0 mg/m3 in the mines with concentration of silicon dioxide dust over 70%.
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PMID:[Evaluation of effects of dust prevention in the principal tungsten mines in Jiangxi]. 234 Jul 65

A case of generalised scleroderma is reported in a dental technician exposed to the risk of silicosis. A study of the occupational toxic risks in this patient showed pulmonary overload with silica and metallic particles composed of chromium, cobalt and tungsten. The job also involved the handling of vinyl chloride and its stable polymer. This chemical is known to give rise to scleroderma-type skin disease. The relationship between these occupational factors leads to a difficult physio-pathological problem and justifies preventative measures, even though they may be costly and demanding.
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PMID:[Erasmus syndrome in a dental technician. Importance of the prevention of occupational hazards]. 666 4

Historical data on the dust exposures of Chinese workers in metal mines (iron/copper, tin, tungsten) and pottery industries are being used in an ongoing joint Chinese/United States epidemiological study to investigate the exposure-response relationship for the development of silicosis, lung cancer, and other diseases. The historical data include 'total dust' concentrations determined by a Chinese method. Information about particle size distribution and the chemical and mineralogical content of airborne particles is generally not available. In addition, the historical Chinese sampling strategy is different from a typical American eight-hour time-weighted average (TWA) sampling strategy, because the Chinese samples were collected for approximately 15 minutes during production so the sample could be compared to their maximum allowable concentration (MAC) standard. Therefore, in order to assess American respirable dust exposure standards in light of the Chinese experience, factors are needed to convert historical Chinese total dust concentrations to respirable dust concentrations. As a part of the joint study to estimate the conversion factors, airborne dust samples were collected in 20 metal mines and 9 pottery factories in China during 1988 and 1989 using three different samplers: 10mm nylon cyclones, multi-stage 'cassette' impactors, and the traditional Chinese total dust samplers. More than 100 samples were collected and analysed for each of the three samplers. The study yielded two different estimates of the conversion factor from the Chinese total dust concentrations (measured during production processes) to respirable dust concentrations. The multivariate analysis of variance (MANOVA) reveals that, with a fixed sampling/analysis method, conversion factors were not statistically different among the different job titles within each industry. It also indicates that conversion factors among the industries were not statistically different. However, the two estimates consistently showed that conversion factors were the lowest in the pottery industry. Average conversion factors were then calculated for each of the estimates across the industries studied. A pooled mean conversion factor, 0.25+/-0.04, was then derived for all the job titles and industries. Respirable dust levels were estimated from the historical 'total dust' concentrations collected between 1952 and 1992 by adopting the American standard.
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PMID:Estimating factors to convert Chinese 'Total Dust' measurements to ACGIH respirable concentrations in metal mines and pottery industries. 1083 29

Collaborative studies of Chinese workers, using over four decades of dust monitoring data, are being conducted by the National Institute for Occupational Safety and Health (NIOSH) and Tongji Medical University in China. The goal of these projects is to establish exposure-response relationships for the development of diseases such as silicosis or lung cancer in cohorts of pottery and mine workers. It is necessary to convert Chinese dust measurements to respirable silica measurements in order to make results from the Chinese data comparable to other results in the literature. This article describes the development of conversion factors and estimates of historical respirable crystalline silica exposure for Chinese workers. Ambient total dust concentrations (n>17000) and crystalline silica concentrations (n=347) in bulk dust were first gathered from historical industrial hygiene records. Analysis of the silica content in historical bulk samples revealed no trend from 1950 up to the present. During 1988-1989, side-by-side airborne dust samples (n=143 pairs) were collected using nylon cyclones and traditional Chinese samplers in 20 metal mines and nine pottery factories in China. These data were used to establish conversion factors between respirable crystalline silica concentrations and Chinese total dust concentrations. Based on the analysis of the available evidence, conversion factors derived from the 1988-1989 sampling campaign are assumed to apply to other time periods in this paper. The conversion factors were estimated to be 0.0143 for iron/copper, 0.0355 for pottery factories, 0.0429 for tin mines, and 0.0861 for tungsten mines. Conversion factors for individual facilities within each industry were also calculated. Analysis of variance revealed that mean conversion factors are significantly different among facilities within the iron/copper industry and within the pottery industry. The relative merits of using facility-specific conversion factors, industry-wide conversion factors, or a weighted average of the two are discussed. The exposure matrix of the historical Chinese total dust concentrations was multiplied by these conversion factors to obtain an exposure matrix of historical respirable crystalline silica concentrations.
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PMID:Estimating historical respirable crystalline silica exposures for Chinese pottery workers and iron/copper, tin, and tungsten miners. 1171 59

To provide a scientific basis for determining the health surveillance period of dust-exposed workers, data of a retrospective cohort study was re-analyzed with emphasis on natural course of silicosis. 33640 workers exposed to silica dust who were employed for at least 1 year from 1972 to 1974 in twenty Chinese mines or pottery factories were included as subjects, and were followed up till December 31, 1994. The cohort included subjects from 8 tungsten mines, 4 tin mines and 8 pottery factories. Our results showed that the mean latency of silicosis, for all the cases of the cohorts, was 22.9 +/- 9.8 y. 52.2 % of silicosis was diagnosed approximately 9.1 +/- 5.7 y after the dust exposure had ceased. The progression rates of silicosis from stage I to II and from stage II to III were 48.2 % and 18.5 %, and the duration was 4.1 +/- 0.2 and 6.8 +/- 0.2 y, respectively. The survival times of silicosis stage I , II and III, from the year of diagnosis to death, were 21.5, 15.8 and 6.8 years, respectively. There was 25 % of the silicosis patients whose survival time was beyond 33 y. The mean death age of all silicosis cases was 56.0 y. The death age increased to 65.6 y in the middle of 1990s. Among dust-exposed workers, subjects who became suspected case (0+ ) accounted for 15.0 %. 48.7 % of the suspected silicosis cases developed to silicosis, and the average year from the time of being suspected of the disease to the first stage of silicosis was 5.1 y. The natural characteristics, as mentioned above, varied with different mines and factories. We are led to conclude that silicosis is chronic in nature, but progress quickly. As a serious occupational disease it significantly reduces the life span of exposed workers. The study of its natural history is of importance for the development of health surveillance criteria for dust-exposed workers.
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PMID:Natural course of silicosis in dust-exposed workers. 1685 Jul 63