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

Silicas and silicates are some of the most abundant compounds found naturally in the earth's crust. Excessive exposure to crystalline silicas can cause serious lung disease such as silicosis and has been associated with lung cancer in some studies, but the potential health effects of amorphous silicas (silicon dioxide without crystalline structure) have not been well studied. Results from animal studies of amorphous silicas, unlike those seen with crystalline silicas, have suggested limited and largely reversible cytotoxic and possibly fibrogenic effects associated with some forms, but data on cancer outcomes are scanty and for the most part negative. Epidemiologic investigations to date for any potential cancer risk are not informative because the effects of crystalline and amorphous silicas have not been separated. Any future epidemiologic study should attempt to clarify the health effects of amorphous silicas from those of crystalline silicas, particularly with regard to any potential for carcinogenicity.
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PMID:Amorphous silica: a review of health effects from inhalation exposure with particular reference to cancer. 1527 29

Our objective was to examine the relationship between silicosis and esophageal cancer in Hong Kong. The mortality of esophageal cancer was investigated among caisson and non-caisson workers in a cohort of 2,789 male silicotic workers in Hong Kong during the period 1981-99. The standardized mortality ratio (SMR) was calculated using the Hong Kong general population rates as reference. The indirect method proposed by Axelson was used to adjust for the confounding effects of cigarette smoking and alcohol drinking. The SMR of esophageal cancer in the entire cohort was 2.22 (95% CI 1.36-3.43, based on 20 deaths) and was 4.21 (95% CI 1.81-8.30, based on 8 deaths) in the subgroup of caisson workers who had a higher exposure to silica dust. The relative risk of esophageal cancer for caisson silicotics was reduced to 2.34 after adjusting for the effects of smoking and alcohol drinking. No more excess risk of esophageal cancer was observed among non-caisson silicotic workers after the adjustments. This historical cohort study revealed that there was an increased mortality risk of esophageal cancer among silicotics who had worked in underground caissons in Hong Kong after adjusting for cigarette smoking and alcohol drinking. We believe that the excess risk of esophageal cancer mortality among caisson workers with silicosis could best be explained by the very heavy exposure to free silica dust in their working environment.
Int J Cancer 2005 Apr 10
PMID:Further evidence for a link between silica dust and esophageal cancer. 1557 19

Particulates refer to particles, dust, dirt, soot and aerosol mists that has suspended in the surrounding air. They may consist of solids of various forms including fibres or liquids. Long term exposure to silicon dioxide containing dusts (crystalline silica: quartz, tridymite, cristobalite, coesite, stishovite) may cause pneumoconiosis in the form of acute or/either chronic silicosis. Asbestos refers to a divers family of crystalline hydrated fibrous siliates typically exhibiting a greater tha 3:1 length ot diameter ratio. It is subdivided into serpentine (Chrysotile) and amphibole (crocidolite, amosite, anthophyllite, tremolite, actinolite). Exposure to asbestos fibres may cause lung fibrosis and promote cancer of the lung or the pleura. Besides the induction of malignant diseases dust exposure may result in obstructive as well as restrictive lung diseases which may be compensate in case of the recognition as a occupational diseases. Other occupational exposures leading to pneumoconiosis are caused be talc, or metals including aluminium containing dusts. Also the group of man-made mineral (MMMFs) or vitreous fibres (MMVFs), including glass wool, rock wool, slag wool, glass filaments, microfibres, refractory ceramic fibres are bioactive under certain experimental conditions. Although it has been shown that MMMFs may cause malignancies when injected intraperitoneally in high quantities in rodents, inhalation trials and human studies could not reproduce these results in the same precision. Fine particles (particulate matter = PM) comprise one of the most widespread and harmful air pollutants in the industrialized world. PM may cause worsening of asthma and other respiratory diseases, reduce lung function development in children, potentially increased the risk of premature death in the elderly and enhance mortality from cardiac diseases. Because of the small size PM2.5 is seen to be even more hazardous than PM10.
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PMID:[Health significance of inhaled particles]. 1654 43

Exposure to respirable cristalline silica dust during construction activities can cause silicosis and, in accordance with International Agency for Research on Cancer (IARC), even lung cancer. Among the different facets of construction, residential buildings are of particular interest because the lack of exposure data for workers employed. In this sector a dry sand-blasting of brick ceiling and renewal activities has been investigated. The survey has been carried out in a civil dwelling and 58 samples have been collected using the SKC aluminium cyclone and Door-Oliver plastic cyclone at flow-rate 2.2-1.7 l/min. The respirable dust samples were analysed by x-ray diffraction using NIOSH Method 7500. Even if the results of this study should be considered preliminary, they showed SLC respirable concentrations even many time above TLV-TWA during a sand-blasting activities and some times also during the other activities. Awaiting the correct classification from European Community, it would be desiderable that the workers would had appropriate information and prevention on the specific risks associated to the dust in the construction activities.
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PMID:[Exposure to crystalline silica in the air during renovation of residential buildings]. 1680 70

Cigarette smoking and silicosis are potential causes of lung cancer among workers exposed to silica dust, but their joint effects are unclear. We explored the possible interactions between silicosis and smoking on lung cancer risks by summarizing data from the published literature. The standardized mortality ratio or standardized incidence ratio reported in each published report was first adjusted using "smoking adjustment factors" to correct for the biased estimation of the expected numbers of lung cancer among smokers and nonsmokers when using general population rates in the indirect standardization process. The ratio of the effect of silicosis on lung cancer risk among smokers to that among nonsmoker was calculated and named the "relative silicosis effect (RSE)". The synergy index was estimated to assess the additive interaction. Metaanalyses were used to obtain the weighed means of the RSE and synergy index. Ten cohort studies were reviewed and combined to yield a weighed RSE of 0.29 (95% CI: 0.20, 0.42), indicating negative risk-ratio multiplication between smoking and silicosis on the lung cancer risk. The combined weighed synergy index was 1.00 (95% CI: 0.79, 1.26), suggesting no departure from additivity. Sensitivity analyses showed that both estimates were quite robust. The independent risk-ratio effect of silicosis on lung cancer in smokers was about 30% of that in nonsmokers, and the joint effects of smoking and silicosis on the risk of lung cancer did not deviate from additivity and hence did not support biological synergism/antagonism.
Int J Cancer 2007 Jan 01
PMID:Exploring the joint effects of silicosis and smoking on lung cancer risks. 1703 27

Ataxia-telangiectasia is an autosomal recessive disease characterized by neurological and immunological symptoms, radiosensitivity and cancer predisposition. Heterozygous carriers of an ataxia-telangiectasia gene mutation are predisposed to epithelial cancers. We initiated a study to elucidate the frequency and clinical relevance of ATM gene mutations in former uranium miners exposed to high levels of radiation from radon and its decay products. Former uranium miners with Schneeberg lung cancer (n=48), former uranium miners suffering from silicosis (n=60) and uranium miners without occupational lung disorders (n=102) were investigated for nine mutations in the ATM gene. One gastric and one prostate cancer occurred in the group of miners without occupational lung diseases. Mutation analyses for S707P, IVS10-6Tright curved arrow G, 2250Gright curved arrow A, E1978X, R2443X, 3801delG, S49C and D2625E-A2626P were performed using genomic DNA obtained from peripheral blood samples. Three ATM gene alterations (S707P, S49C or IVS10-6Tright curved arrow G) were observed. Of all cancer patients, 8.0% were heterozygous, but only 1.9% of the non-cancer controls were [OR=4.6; 95% confidence interval (CI), 0.8-26.8]. In this pilot study a major role of six ATM gene mutations could not be revealed for cancer predisposition in former uranium miners. The results leave the possibility of a moderate risk associated with more subtle ATM gene alterations.
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PMID:ATM gene mutations in former uranium miners of SDAG Wismut: a pilot study. 1720 91

Silicosis patients (SILs) and patients who have been exposed to asbestos develop not only respiratory diseases but also certain immunological disorders. In particular, SIL sometimes complicates autoimmune diseases such as systemic scleroderma, rheumatoid arthritis (known as Caplan syndrome), and systemic lupus erythematoses. In addition, malignant complications such as lung cancer and malignant mesothelioma often occur in patients exposed to asbestos, and may be involved in the reduction of tumor immunity. Although silica-induced disorders of autoimmunity have been explained as adjuvant-type effects of silica, more precise analyses are needed and should reflect the recent progress in immunomolecular findings. A brief summary of our investigations related to the immunological effects of silica/asbestos is presented. Recent advances in immunomolecular studies led to detailed analyses of the immunological effects of asbestos and silica. Both affect immuno-competent cells and these effects may be associated with the pathophysiological development of complications in silicosis and asbestos-exposed patients such as the occurrence of autoimmune disorders and malignant tumors, respectively. In addition, immunological analyses may lead to the development of new clinical tools for the modification of the pathophysiological aspects of diseases such as the regulation of autoimmunity or tumor immunity using cell-mediated therapies, various cytokines, and molecule-targeting therapies. In particular, as the incidence of asbestos-related malignancies is increasing and such malignancies have been a medical and social problem since the summer of 2005 in Japan, efforts should be focused on developing a cure for these diseases to eliminate nationwide anxiety.
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PMID:Immunological effects of silica and asbestos. 1776 16

Multiple different types of anterior mediastinal masses may be encountered on computed tomography (CT) imaging, and many of these lesions are neoplastic in etiology. These include masses arising from the thymus, thyroid and parathyroid glands, as well as lymph nodes, pericardium, and vessels and nerves. Often, the CT attenuation of the mass can be helpful in narrowing down the differential diagnosis, and attenuation values suggesting fat, water or calcium may suggest certain diagnoses; significant enhancement of the mass with intravenous contrast may also be a helpful feature. Lesions with fatty attenuation include teratomas, thymolipomas and Morgagni hernias. Lesions that may manifest the attenuation of water include pericardial and thymic cysts, abscesses, and lymphangiomas, as well as neurogenic and germ cell tumors. Multiple types of lesions may contain calcium, including thyroid goiters and cancers, thymomas, thymic carcinomas and carcinoids, treated lymphoma, germ cell tumors, parathyroid adenomas, and lymph nodes involved with silicosis, sarcoid, tuberculosis, fungal diseases and pneumocystis. Contrast enhancement may be seen in lesions of vascular origin and in vascular neoplasms, such as parathyroid adenomas and Castleman's disease. In addition to CT attenuation values, the exact location and morphology of the mass in question, in conjunction with clinical features such as patient age, gender, signs, symptoms, and laboratory values, can usually lead to a short list of possible etiologies, thereby directing appropriate additional diagnostic procedures or therapeutic approaches.
Cancer Imaging 2007 Oct 01
PMID:Imaging of anterior mediastinal masses. 1792 Oct 91

The aim was to assess radiographic features of pulmonary malignancies in silicosis and to reveal confounding factors in their detection. A total of 501 silicosis patients were followed up between 1982 and 2003. Sixty pulmonary malignancies were pathologically confirmed in 54 (10.8%) patients. Two radiologists reviewed serial radiographs of these patients to determine radiographic features of tumor (size, margin, nodule or consolidation, localization, overlying structures) and silicosis (profusion of pneumoconiotic opacities, progressive massive fibrosis (PMF), hilar lymphadenopathy). Eleven tumors were radiographically negative. Forty-nine tumors were retrospectively visible with radiograph. Of these, 15 tumors were clinically detected with radiograph, but 25 were missed. The remaining nine tumors became radiographically positive after positive sputum cytology. There were no differences between missed and detected nodules in terms of radiographic findings. The mean tumor size was 30mm (range: 15-90mm) and was significantly larger in patients with PMF or hilar lymphadenopathy than in those without (35mm vs. 24mm, p=0.006; 33mm vs. 24mm, p=0.038, respectively). This was correlated with background profusion of small pneumoconiotic opacities (r=0.433, p=0.024). Retrospective reading tests by three radiologists showed correct localization of tumor in 75%, however, the correct diagnosis with a high confidence was reached in only 54%. In conclusion, radiographic detection of malignancy in silicosis proved a difficult task and no single radiographic finding was found to be associated with missing the tumor. The presence of PMF, hilar lymphadenopathy and profusion of small pneumoconiotic nodules affected tumor size at detection.
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PMID:Pulmonary malignancy in silicosis: factors associated with radiographic detection. 1792 65

Inhalation of the crystalline form of silica is associated with a variety of pathologies, from acute lung inflammation to silicosis, in addition to autoimmune disorders and cancer. Basic science investigators looking at the mechanisms involved with the earliest initiators of disease are focused on how the alveolar macrophage interacts with the inhaled silica particle and the consequences of silica-induced toxicity on the cellular level. Based on experimental results, several rationales have been developed for exactly how crystalline silica particles are toxic to the macrophage cell that is functionally responsible for clearance of the foreign particle. For example, silica is capable of producing reactive oxygen species (ROS) either directly (on the particle surface) or indirectly (produced by the cell as a response to silica), triggering cell-signaling pathways initiating cytokine release and apoptosis. With murine macrophages, reactive nitrogen species are produced in the initial respiratory burst in addition to ROS. An alternative explanation for silica toxicity includes lysosomal permeability, by which silica disrupts the normal internalization process leading to cytokine release and cell death. Still other research has focused on the cell surface receptors (collectively known as scavenger receptors) involved in silica binding and internalization. The silica-induced cytokine release and apoptosis are described as the function of receptor-mediated signaling rather than free radical damage. Current research ideas on silica toxicity and binding in the alveolar macrophage are reviewed and discussed.
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PMID:Silica binding and toxicity in alveolar macrophages. 1822 3


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