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

Michigan has a statewide mandatory occupational disease reporting system. As part of that system, reports are received from hospital, physicians, death certificates, the worker's compensation bureau, and company medical departments. Based on this reporting, the State of Michigan has a special emphasis program for the surveillance of silicosis, a known disease outcome among foundry workers. From 1985-1996, 115 cases reported to the State Surveillance System as silicosis, pneumoconiosis not specified, or pulmonary fibrosis were reclassified as having asbestos related x-ray changes after a B-reader interpretation of each case's chest x-ray. During this same period there were an additional 697 reports confirmed as silicosis and 6,724 cases reported to the surveillance system as asbestosis. Among the 115 reports reclassified as having asbestos-related x-ray changes without evidence of silicosis-related x-ray changes, 54 had worked in foundries. Only 7 (14.8%) of these individuals had their primary work in maintenance in the foundry; 40 (85.1%) had their primary foundry work in a production job; and for 10 individuals the occupation was not known. Asbestos has been used in foundries on pipe laggings, boiler coverings, as insulation in fan housings, in gloves, aprons and curtains, as insulation in cupolas, and in ladles and insulation in sand molds. Clinicians caring for foundry workers need to be aware that asbestos-related x-ray changes are not uncommon in this population and asbestos exposure should be considered as one of the carcinogens contributing to the known increased risk of lung cancer among foundry workers.
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PMID:Asbestos-related x-ray changes in foundry workers. 1227 84

A case-control study, nested in a cohort of workers under surveillance for silicosis in 1979 or later, was undertaken to assess lung cancer risk in relation to the ILO coding scheme for the pneumoconioses. The subjects of this study are from the 41 matched quarters, consisting of one workers with silicosis and three age-matched controls, in which a lung cancer case was diagnosed. The odds ratio for lung cancer among subjects with ILO classification 1/0 or more, in comparison to subjects with category < or = 0/1, was 3.27 (95% CI =1.32-8.2). Adjustment of the radiographic risk for the effect of cumulative radon exposure had the effect of increasing the odds ratio for the association between ILO category > or = 1/0 and lung cancer. Although small smoking differences could account for the increased lung cancer odds ratio among workers with silicosis, the empirical evidence suggests that these smoking differences do not exist. It is concluded on the basis of two North American studies of silica exposed workers that radiographic silicosis is a marker for an increased risk of lung cancer.
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PMID:Radiographic silicosis and lung cancer risk among workers in Ontario. 969 93

Installation and removal of conventional refractories and refractory ceramic fiber (RCF) in industrial furnaces may lead to occupational exposure to respirable crystalline silica (including quartz, cristobalite, and tridymite). Exposure to elevated concentrations of these materials has been linked to adverse respiratory effects, including silicosis and lung cancer. Unlike conventional refractories, RCF does not contain any of these materials as produced. However, depending upon time and temperature during the service life of the insulation, RCF may partially devitrify, creating the potential for exposure upon removal of after-service insulation. For removal of after-service RCF, exposure data collected as part of a 5-year consent agreement with EPA are presented and analyzed. Because of relatively low concentrations of these materials, limitations on the sensitivity of the analytical method, and the relatively short duration of furnace removal activities, many measurements are less than the limits of detection (LODs), creating challenges for data analysis. Several methods of analysis of censored data are illustrated and the theory of maximum likelihood estimates is generalized to cover the case of multiple LODs. Average exposures to these materials associated with removal of after-service RCF are compared to those in various industries.
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PMID:Respirable crystalline silica exposure associated with the installation and removal of RCF and conventional silica-containing refractories in industrial furnaces. 1005 18

An analysis of death certificates from 1987 to 1996 among residents of the Tuscany Region identified 1518 deaths from pneumoconiosis, the large majority from silicosis, a disease explained by occupational exposure to silica dust. A dozen of deaths are from asbestosis, occurred at younger ages and are concentrated in a restricted area where a cement-asbestos factory was active. Deaths from pneumoconiosis occurred mainly among males, and the rates of the disease are decreasing only in the latest years. About 10% of deaths from silicosis are among subjects dying before 65 years of age. Mortality rates are very high in several areas of the Region, approximating those from lung cancer and ischaemic heart disease. For the above reasons the disease is still of concern from the point of view of public health and actions are suggested to obtain a description of prevalence and incidence of the disease.
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PMID:[The mortality due to pulmonary silicosis in the Tuscany region in the last decade demonstrates that the health effects of work exposure to silica are still marked]. 1005 60

Using polymerase chain reaction single strand conformation polymorphism analysis (PCR-SSCP), the authors mutations in exon 5, 7 and 8 of the p53 gene in lung cancer tissue from 15 of 36 silicotic patients. Mutations existed in exon 5, exon 7 and exon 8, but occured more frequently in exon 8. The authors also found that p53 gene mutation rate in lung adenocarcinomas of silicotic patients was higher than that of those without silicosis. A single base substitution was found by DNA sequencing analysis in sample C8. As a result, No. 144 codon was mutated from CAG to AAG, so Gln was substituted by Lys. The authors' data suggest that p53 mutation may play an important role in the pathogenesis of lung cancer of silicotic patients.
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PMID:[The research on p53 gene mutation in lung cancer tissue of silicotic patients by PCR-SSCR]. 1032 39

To examine any association between silicosis and lung cancer, the clinic records of a cohort of 1502 silicotic workers diagnosed after 1981 were reviewed. All of the essential data, including occupational exposure, smoking habits, radiographic extent of silicosis, and vital status of each subject, were noted. The standardized mortality ratio for various causes of death was calculated. Thirty-three patients died from lung cancer, giving a standardized mortality ratio of 1.94 (95% confidence interval, 1.35 to 2.70). However, smoking accounted for most of the excess of lung cancer deaths among the silicotic workers in the cohort, and no consistent relationship between lung cancer mortality risk and either duration of exposure to silica dust or severity of silicosis was observed. There is no conclusive evidence in our data to support the hypothesis that lung cancer may be associated with silicosis.
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PMID:Lung cancer mortality among a cohort of men in a silicotic register. 1099 60

In view of the extended debate and differing opinions on whether crystalline silica is a human carcinogen, we have reviewed a selection of epidemiological reports, to identify the areas of uncertainty and disagreement. We have chosen to examine the papers which in a recent review were considered to provide the least confounded examinations of an association between silica exposure and cancer risk. We also refer to a study of the mortality of coalminers very recently reported by ourselves and colleagues. We find that parts of the evidence are coherent but there are contradictions. On examination this resolves mostly into differences between types of studies. The three types of epidemiological study included are: (i) exposure-response studies, the most powerful for the confirmation of a relationship between a specific exposure and a health effect; (ii) descriptive studies in which incidence of disease in an exposed population is compared with that in a reference population; and (iii) studies of incidence of disease in subjects on silicosis case-registers. Descriptive studies frequently though not invariably suggest an excess lung cancer risk in silica-exposed workers compared with the general population, but exposure-response studies consistently fail to confirm that the cause is exposure to quartz. A single exposure-response study of cristobalite suggests a positive relation. Both sets of evidence have weaknesses. There are uncertainties on whether the excess risks in the descriptive studies are related to silica exposure or to lifestyle, including smoking habits. There are doubts on whether the exposure estimates in some of the exposure-response studies were sufficiently reliable to detect a small risk or weak association, though they are unlikely to have missed a strong effect. Studies of subjects on silicosis case registers consistently show an excess of lung cancer, but it is not clear to what extent these increased risks represent a direct effect of silica exposure, a secondary effect of the silicosis, preferential inclusion of subjects suffering from the effects of smoking, or bias in diagnostic accuracy. This not unnaturally leads to differences in opinion, exacerbated by variations in the strength of proof required by different experts. The main scientific uncertainties in the evidence are: 1. Whether, in the descriptive studies, the excess lung cancer rates in silica-exposed workers are explicable in terms of smoking habits, socio-economic class differences and inappropriate comparison populations. Better smoking information and more carefully chosen comparison populations are needed; 2. Whether the exposure-response studies could have missed a real relationship between silica exposure and lung cancer, if one exists. Many of the exposure-response studies were conducted with great care, but weaknesses, in the available data on which the exposure estimations were based, could have caused a real relationship of lung cancer and silica exposure to be missed. These studies were sufficiently powerful to demonstrate relationships of silica exposure with silicosis and silico-tuberculosis, so it is unlikely that they would have missed any but a small risk, or weak relationship, for lung cancer. Our own recent study of coalminers used uniquely detailed and reliable exposure data, and failed to demonstrate convincingly an increased risk. This negative finding, though, applies only to a dust in which the proportion of quartz in the dust is usually less than 10%. Exposure-response studies are needed, with high quality exposure estimates, in populations exposed to respirable dust of which crystalline silica comprises more than 10%; 3. Whether the excess cancer risks in subjects on silicosis registers are the result of selection and diagnostic bias. Given these difficulties, case-register studies may not be capable of giving a reliable answer to the central question, though they have been useful in pointing to the possibility of a can
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PMID:Epidemiological evidence on the carcinogenicity of silica: factors in scientific judgement. 1102 42

Tl-201 lung uptake in 74 patients (85 lesions) and pulmonary perfusion in 105 patients were studied to evaluate clinical usefulness of Tl-201 lung uptake and perfusion lung scintigraphy in pulmonary tuberculosis, using a scintillation camera with a mini-computer system. As indices of Tl-201 lung uptake, lung (lesion) to upper mediastinum uptake ratio (L/M) and visual grading were used. L/M in pulmonary tuberculosis was 1.96 +/- 0.66, which was significantly larger than 1.04 +/- 0.24 in healthy controls and lower than that in heart diseases with left heart failure and idiopathic interstitial pneumonia, and showed no significant differences with that in acute pneumonia, pyothorax, primary lung cancer and malignant mediastinal tumor. L/M in pulmonary tuberculosis did not correlate with CRP, erythrocyte sedimentation rate, Gaffky number of sputum and body temperature. It correlated with the type of pulmonary tuberculosis according to the Gakken Classification reflecting the disease activity. It was larger in the exudative type, caseo-infiltrative one, disseminated one, one with cavity in infiltrative lesion than the fibro-caseous one. On perfusion lung scintigram, impairment of pulmonary perfusion larger than area of the entire unilateral lung was observed in 68 cases (64.8%). Area of hypoperfused lung field, which correlated with % vital capacity (r = 0.60, p = 0.0002) and PaO2 (r = 0.39, p = 0.0024), was significantly larger in patients with silicosis and those with bilateral pleural involvements such as pleural callosity than in those with type III according to the Gakkai Classification. Most of the patients showed decreased pulmonary perfusion and Tl-201 accumulation of which grade reflects the disease activity in active tuberculous lesion. Patients with miliary tuberculosis and those with silicotuberculosis showed diffuse Tl-201, accumulation in the both lungs. Tl-201 lung scintigraphy seems to be useful for visualizing active tuberculous lesions, particularly the ones that could not be detected by the chest radiograph in patients with destroyed lung and with pleural callosity. Joint use of Tl-201 and perfusion lung scintigraphies provides useful informations about the pathophysiology and disease process in pulmonary tuberculosis.
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PMID:[Evaluation of Tl-20 lung uptake and impairment of pulmonary perfusion on scintigraphies in pulmonary tuberculosis]. 1072 41

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

The objective of this study was to explore whether a medical history for non-malignant respiratory disease contributes to an increased lung cancer risk among workers exposed to silica. We analyzed data from a nested case-control study in 29 dusty workplaces in China. The study population consisted of 316 lung cancer cases and 1356 controls matched to cases by facility type and decade of birth who were alive at the time of diagnosis of the index case and who were identified in a follow-up study of about 68,000 workers. Age at first exposure and cigarette smoking were accounted for in the analysis. Smoking was the main risk factor for both lung cancer and chronic bronchitis. Lung cancer risk showed a modest association with silicosis and with cumulative silica exposure, which did not vary by history of previous pulmonary tuberculosis. Among subjects without a medical history for chronic bronchitis or asthma, lung cancer risk was associated with silicosis (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1 to 2.2), and it was increased in each quartile of cumulative silica exposure. However, risk was not elevated in the highest quartile (OR, 1.3, 1.6, 1.8, 1.4). Among subjects with a medical history for chronic bronchitis or asthma, lung cancer risk was associated with neither silicosis (subjects with chronic bronchitis: OR, 0.6; subjects with asthma: OR, 0.4) nor with silica exposure. In this study population, we observed a modest association of both silicosis and cumulative exposure to silica with lung cancer among subjects who were not previously diagnosed with chronic bronchitis or asthma, but not among subjects who had a medical history for either disease. Risk of lung cancer associated with silicosis or cumulative exposure to silica did not vary by previous medical history of pulmonary tuberculosis.
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PMID:Non-malignant respiratory diseases and lung cancer among Chinese workers exposed to silica. 1087 57


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