Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0037116 (silicosis)
 1,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Toxic potency of quartz-containing dusts, including coal mine dusts, is usually inhibited by protective clay mineral layers on the surface of quartz particles. This investigation of 11 dusts recovered from lungs of coal miners with different silicosis grade shows that such layers persist during long-term contact with human lung tissues. On the other hand, the results suggest that an apparently preferential release of iron occurred in lungs with massive fibrosis. These preliminary results support the hypothesis of an iron-related harmfulness of coal mine dusts.
 ...
PMID:Biopersistence of the mineral matter of coal mine dusts in silicotic human lungs: is there a preferential release of iron? 788 48

Approximately 100 000 Finnish workers are currently employed in jobs and tasks that may involve exposure to airborne silica dust. The major industries involved are mining and quarrying; production of glass, ceramics, bricks and other building materials; metal industry, particularly iron and steel founding; and construction. Over 1500 cases of silicosis have occurred in Finland since 1935. Tuberculosis has been a frequent complication of silicosis. Results of studies from several countries strongly suggest that silica dust also causes lung cancer. The results of the relevant Finnish epidemiologic and industrial hygiene studies addressing cancer risk and exposure to quartz dust are summarized.
 ...
PMID:Silica, silicosis and cancer in Finland. 892 99

Iron oxides are present in many occupational atmospheres mainly in iron ore mines and in steel industry. Among these workers, epidemiological studies indicated an excess of lung cancer deaths. In mines, it was difficult to involve iron oxides exposure because there are other possible causes as radon, polycyclic aromatic hydrocarbon (PAH) present in diesel exhausts, silicosis or siderosis. The contradictory results of these studies are due to the differences of exposure levels or to the presence or not of these cofactors or of a sufficient prevention. But generally the results agree with an interaction of iron oxide dusts and smoking habits. It is unclear if this interaction supports an additive or multiplicative risk of lung cancer. Experimental studies with Fe2O3 showed that these particles are able to induce lung cancers only in the presence of PAH when administered to animals. In vitro studies permitted to observe an interaction in the metabolism of benzo(a)pyrene (BaP) leading to a higher level of precursors of the ultimate carcinogen. As this metabolism of BaP is known to be enhanced during lipoperoxidation, it is possible to involve this mechanism with Fe2O3. After phagocytosis and dissolution with production of ferric ions, Fe2O3 can enhance the production of reactive oxygen species responsible of damaging both lipidic constituents and DNA. Fe3O4 and mainly FeO may be more toxic, introducing directly ferrous ions in the cells after dissolution, but the cancerogenicity of the these compounds is unknown, making necessary to develop research.
 ...
PMID:Interactive effects of polycyclic aromatic hydrocarbons and iron oxides particles. Epidemiological and fundamental aspects. 916 58

In vivo exposure of rat lungs to crystalline silica either by intratracheal instillation or by inhalation results in an increase in mRNA levels for inducible nitric oxide synthase (iNOS) in bronchoalveolar lavage cells (BALC), elevated nitric oxide (.NO) production by BALC, and an increase in .NO-dependent chemiluminescence (CL) from alveolar macrophages (AM). Induction of iNOS message occurs in both AM and polymorphonuclear leukocytes (PMN) harvested from silica-exposed lungs but is not significantly elevated in lavaged lung tissue. In vitro exposure of AM to silica does not stimulate .NO production or enhance iNOS message. However, treatment of naive AM with conditioned media from BALC harvested from silica-exposed rats does increase iNOS message and .NO production by these AM. The potency of this conditioned medium is dependent on interaction between AM and PMN. In the rat model, a relationship exists between the ability of various dusts to cause PMN recruitment or protein leakage into the alveolar space and the induction of iNOS message in BALC, i.e., silica > coal mine dust > carbonyl iron > titanium dioxide. Similarly, a comparison of BALC from a healthy volunteer, a silica-exposed coal miner with a normal chest radiograph, and a silica-exposed coal miner with an abnormal chest radiograph shows a correlation between pathology and both the level of iNOS message in BALC and the magnitude of .NO-dependent CL from AM. These data suggest that .NO may play a role in silicosis and that human pulmonary phagocytes exhibit enhanced .NO production in response to an inflammatory insult.
 ...
PMID:Enhancement of nitric oxide production by pulmonary cells following silica exposure. 978 92

Silicosis is an important disease not only for its prevalence and the degree of pulmonary insufficiency it entails but also because it provides a natural model of interstitial fibrotic disease in the lung which is of known origin. This can, in turn, help us understand the pathogenic nature of a great number of pulmonary fibroses whose cause is unknown. The fifty postmortem studies which we describe correspond to miners who had worked in underground mines in the mountainous region near Cartagena (SE Spain) for times ranging from 5 to 36 years. The autopsies showed that they had been exposed to dust containing abundant metallic particles, particularly iron oxide (mixed dust). Although the pathogenic action was related with silica, it was also clearly modified by the composition of the dust associated with it. The basic lesions which are produced in the lung after inhalation of silica (< 5 microns diameter) are coniosis, fibroconiosis and sclerohyalinosis. The sclerohyalino nodules are characterized by abundant collagenization and hyalinization, different types of which can be distinguished according to the disposition of the collagenous fibres. Nodular lesions gradually grow in size even when exposure to dust has ceased. As they grow they get nearer until they join to form conglomerate masses. When the diameter exceeds 3 cm this is called massive fibrosis. Pulmonary tuberculosis was found in 27% of cases. This took the form of lesions, which could be associated to or independent of silicotic lesions. Besides evolutive nodular lesions, a patient suffering from silicosis may show other unspecific lesions which must be correctly evaluated for a more correct clinical-pathological assessment, since, clinically, the respiratory function may be profoundly affected although such silicotic damage may be not very noticeable by radiological examination. Silicosis of the liver and spleen was not infrequent in the autopsies carried out, with basic lesions in all evolutive states being observed, the most evolved in the spleen. This means that silicosis should be considered as a systemic illness.
 ...
PMID:[Pulmonary fibrosis caused by inhalation: silicosis]. 1042 Sep 32

Six males with systemic sclerosis were observed in the work forces of two iron ore mines. The usual spectrum of clinical features encountered in systemic sclerosis patients were present. Histologic examination of pulmonary tissue was performed on three of the cases and showed features of both silicosis and scleroderma but to different degrees and stages of development. Exposure to high levels of silica-containing dusts had occurred in all six cases.
 ...
PMID:Systemic sclerosis (scleroderma) in two iron ore mines. 1045 97

This paper aims to illustrate the conditions selected at the Clinica del Lavoro of the University of Milan to prepare and analyze a large number of fine dust samples produced over a period of about 50 years, that were initially used for studies within the Clinic performed in its own facilities, and since 1956 were sent to other Italian and overseas laboratories (Luxembourg, UK, Germany, Norway, Sweden, South Korea, USA). The total quantity of material distributed (with maximum size 7-10 microns) was about 2 kg and consisted of the following mineral and artificial compounds: quartz, HF-treated quartz, tridymite, HF-treated tridymite, cristobalite, chromite, anthracite, quartz sand for foundry moulds, sand from the Lybian desert, vitreous silica, pumice, cement, as well small quantities of metallic oxides, organic resins, chrysotile, crocidolite, fibres (vitreous, cotton and polyamidic). About half of the entire quantity of dusts produced consisted of partially HF-treated tridymite. Initially, research on the etiology of silicosis used quartz dust samples, simply sieved or ventilated (consisting of classes finer than 0.04 mm, containing a 15-20% respirable fraction). From 1956 to 1960 the dusts were produced by manual grinding in an agate mortar, below about 10 microns, starting from quartz from Quincinetto (near Ivrea, Province of Turin), containing about 99.5% quartz: particle size and composition were checked using an optical-petrographic technique, with identification of the free and total silica content. Subsequently, the dusts used for biological research were obtained by grinding coarse material with a cast iron pestle and planetary mills, agate and corundum jars. The grinding products were sized by means of centrifugal classification, using the selector developed by N. Zurlo, ensuring control of dust size both optically and by means of wet levigators and hydraulic classifiers (in cooperation with the Institute of Mines of Turin Polytechnic School). After 1990 pestles and rotating drum mills with autogenic grinding load were used for grinding: the size of the treated samples was reduced to 0.05 mm and an extremely fine fraction was extracted, smaller than 7-10 microns, which was used for pneumoconioses research. The characterization of the dust produced was in any case achieved by means of preliminary examination under the optical microscope (polarized light, sometimes supplemented with phase contrast), followed by quantitative analysis using chemical/petrographic, chemical diffraction or, more commonly, petrographic/diffraction techniques. Microscopic examination, if necessary supplemented with photo-micrography, was also used for particle size control, for numerical counting and subsequent reference to weight proportion. For all operational procedures the essential data on instruments and methods are reported. During studies on production, separation of fine dusts and their characterization, partly performed with support from the European Community (EEC/European Coal and Steel Commission), the following topics in particular were addressed: connections between particle size and free silica content in the measurable dust size fraction of the grinding products and in airborne dusts; characteristics of the dusts and risk indices in Italian iron and pyrite mines; possibility of abatement of the ultrafine classes of airborne dusts in pneumatically filled stopes by the addition of salts; comparison of the latest dust selectors used within the European Community; influence of the grinding methods on the results of fibrous and soft mineral measurement using X-ray diffraction analysis.
 ...
PMID:[The preparation and characterization of fine dusts carried out in the Clinica del Lavoro di Milano in support of experimental studies]. 1059 45

This work presents the concentrations dynamics of dust in a cast iron foundry, in parallel with the frequency and gravity dynamics of the getting sick of silicosis. The knowing of the real risk of exposure to silicotic dust was possible through the data processing concerning the dusting degree (the average of working place), the content of silicon free-crystalline dioxide (SiO2 l.c.) for the calculation of the maximum admitted concentration (C.M.A.) and the dispersion degree of dust in a cast iron and steel foundry for the studied period (1982-1996). New cases of silicosis appeared in this period were studied and they were colligated with the age at declaration, the average length of service and the profession. The values of the dusting degree outrun the C.M.A. up to 168 times, especially at the preparation of mixture and grinding with a prevalence of particles under 3 micron (40-70%) and the Si02 l.c. content varies between 35.2% and 64.5%. From those 98 new cases of silicosis appeared in 15 years, 82.65% were traced out in the incipient phases of the disease. The average age in service and the average age increase (43.1 respective 19.8 years). The coefficients of correlation and regress (+0.286 respective +0.383) show a good correlation between the silicosis number and the age in service. The advanced stages of silicosis and age in service under 10 years were found at the foundry-workers and formators, occupations which imply a high silicotic risk. The foretelling calculations for the next 20 years show an increase of the silicosis incidence for foundry-workers.
 ...
PMID:[The dynamics of exposure to silicotic dusts and silicosis in a foundry]. 1075 97

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.
 ...
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.
 ...
PMID:Estimating historical respirable crystalline silica exposures for Chinese pottery workers and iron/copper, tin, and tungsten miners. 1171 59


<< Previous 1 2 3 4 5 Next >>