silicon and Silicosis

Recent evidence confirms the fundamental involvement of the human immune system in the reaction to implantation of silicone-based medical devices. An as yet-to-be particularized epitope of many complex substances sharing siloxane structures is presented through the MHC-II apparatus with development and retention of T cell memory. This memory can be tested for in practical terms using one or more forms of silica, which links the immuno-histopathology and autoimmune attributes of "silicosis" with those of "siliconosis." The lesions of siliconosis are typical of those for persistent antigens and delayed, cell mediated hypersensitivity. The basic descriptive pathology of the reaction to silicone has been known since soon after introduction of silicones in medical procedures, with the exception of some details related to the more recent discoveries on the role of cytokines in the immunopathic process. The clinical consequences of siliconosis are common and can be severe in some individuals implanted with silicone devices.

Topics: Autoimmune Diseases; Breast Implants; Equipment Failure; Female; Histocompatibility Antigens Class II; Humans; Immunity, Cellular; Immunologic Memory; Major Histocompatibility Complex; Silicon; Silicones; Silicosis; Siloxanes; Superantigens

Approximately three million workers in the United States are estimated to be exposed to silica, man-made mineral fibers, and asbestos. The lung is the primary target organ of concern. Each of these substances is composed predominantly of silicon and oxygen; asbestos and silica are crystalline, and asbestos and man-made mineral fibers are fibers. Man-made mineral fibers and asbestos are used as insulating agents, with the former having generally replaced the latter in recent years. Silica is used in foundries, pottery, and brick making, and is encountered by miners. A meta-analysis of 16 of the largest studies with well-documented silica exposure and low probability of confounding by other occupational exposures, indicates a relative risk (RR) of 1.3 (95 percent confidence interval [CI] = 1.2-1.4). Lung cancer risks are highest and most consistent for silicotics, who have received the highest doses (RR = 2.3, CI = 2.2-2.4, across 19 studies). The data for mineral fibers continue to support the International Association for Research on Cancer's 1988 judgment that mineral fibers are a possible human carcinogen (Group 2B). Recent epidemiologic studies provide little evidence for lung carcinogenicity for either glass wool or rock/slag wool. Ceramic fibers, a much less common exposure than glass wool and rock/slag wool, are of concern because of positive animal studies, but there are insufficient human data. Regarding asbestos, its carcinogenicity for the lung and mesothelium is well established. With regard to the controversy over chrysotile and mesothelioma, the data suggest chrysotile does cause mesothelioma, although it may be less potent than amphibole asbestos.

Topics: Animals; Asbestos; Asbestos, Serpentine; Carcinogens; Ceramics; Confidence Intervals; Confounding Factors, Epidemiologic; Construction Materials; Crystallization; Disease Models, Animal; Glass; Humans; Lung Neoplasms; Mesothelioma; Meta-Analysis as Topic; Mineral Fibers; Mining; Occupational Diseases; Occupational Exposure; Oxygen; Probability; Risk Factors; Silicon; Silicon Dioxide; Silicosis; United States

Topics: Animals; Anti-Bacterial Agents; Antifungal Agents; Anura; Bacterial Infections; Cardiovascular System; Chemical Phenomena; Chemistry; Fungi; Growth; Halogens; Humans; Infections; Insect Repellents; Insecticides; Lethal Dose 50; Metabolism; Mice; Nervous System; Nitrogen; Plants; Rabbits; Radiation-Protective Agents; Rats; Silicon; Silicones; Silicosis; Ultraviolet Rays

Topics: Animals; Chemical Phenomena; Chemistry; Humans; Hypnotics and Sedatives; Polymers; Rabbits; Silicon; Silicones; Silicosis

Topics: Biochemical Phenomena; Biochemistry; Granuloma; Humans; Research; Silicon; Silicosis

Silica (either crystalline or amorphous) is widely used for different applications and its toxicological assessment depends on its characteristics and intended use. As sustained inflammation induced by crystalline silica is at the root of silicosis, investigating the inflammatory effects induced by amorphous silicas and their persistence is needed. For the development of new grades of synthetic amorphous silicas, it is also desirable to be able to understand better the factors underlying potential adverse effects. Therefore, we used an optimized in vitro macrophage system to investigate the effects of amorphous silicas, and their persistence. By using different amorphous silicas, we demonstrated that the main driver for the adverse effects is a low size of the overall particle/agglomerate; the second driver being a low size of the primary particle. We also demonstrated that the effects were transient. By using silicon dosage in cells, we showed that the transient effects are coupled with a decrease of intracellular silicon levels over time after exposure. To further investigate this phenomenon, a mild enzymatic cell lysis allowed us to show that amorphous silicas are degraded in macrophages over time, explaining the decrease in silicon content and thus the transiency of the effects of amorphous silicas on macrophages.

Topics: Humans; Macrophages; Silicon; Silicon Dioxide; Silicosis

The degree of silicosis exposure is closely related to the progress of silicosis. At present, we use animal and human studies to explore whether silicon can be an important exposure marker in the development of silicosis.. Rats were randomly divided into 2 groups: (1) controls; and (2) silicosis. Rats in the silicosis group were killed at 4, 8, 12, 16, 24 h, 3, 7, 14, 21, and 28 days. Hematoxylin-eosin (HE) and immunohistochemistry (IHC) were performed to observe the histomorphology of lung tissue. The expression levels of CC16 and SP-D were detected using ELISA kits. In addition, we conducted a population study. Workers who have been selected to work in an iron mine for more than 1 year as research objects. The population was divided into four groups: silicosis exposure group (workers exposed to silica dust for more than 1 year in an iron mine were selected); patients group (silicosis patients); observation group (evidence of disease not meeting formal diagnostic criteria) and control group. Both the levels of trace silicon in the urine and blood of rats and human subjects were measured with ICP-MS.. Serum levels of silicon were immediately increased in rats exposed to silicon dust. Similarly, our population study revealed that the silicon level in the silica exposure group and the observing group (exposed but no obvious symptoms) were significantly increased over that of the control group (P < 0.05). In subjects with extended exposure to silica, the serum and urine silicon level in exposed workers appeared to rapidly increase, reaching its peak in 1-5 years, followed by a gradual decline thereafter. Workers exposed to dust for less than 10 years were divided into subgroups by 2-year limit. The levels of serum silicon, urine silicon, TGF-β1, and TNF-α were significantly higher than that of control group.. Changes of the serum levels of silicon occurred earlier than the expression of cytokines such as TNF-α, TGF-β

Topics: Administration, Inhalation; Adult; Aged; Animals; Humans; Inhalation Exposure; Iron; Lung; Male; Middle Aged; Mining; Occupational Exposure; Pulmonary Surfactant-Associated Protein D; Rats, Wistar; Silicon; Silicon Dioxide; Silicosis; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha; Uteroglobin

California horses incur a bone fragility syndrome manifested by pathologic fractures. This study investigated gross, radiographic, and histologic features of the disorder as well as relationships with silicosis and levels of heavy metals and trace minerals through a postmortem study of 9 affected and 3 unaffected horses. Bones and soft tissues were evaluated grossly and histologically. Bones, lymph nodes, and lung tissue were evaluated radiographically. Tissues were evaluated for silicon levels, intracytoplasmic crystals, heavy metals, and trace minerals. All 9 affected horses had osteoporosis and clinical or subclinical pulmonary disease due to silicosis (8/9) or pneumoconiosis (1/9). All affected horses had radiographic findings consistent with osteopenia and histologic evidence of osteoporosis characterized by osteopenia, numerous resorption cavities, cement lines, and a mosaic lamellar pattern indicative of multiple remodeling events. Silicosis was characterized by widespread pulmonary granuloma formation with fibrosis; variable tracheobronchiolar and mediastinal granulomatous lymphadenitis; intracellular crystals within lung and lymph node macrophages; and pronounced lymph node fibrosis, focal necrosis, and dystrophic calcification. Crystals in lung (6/9) and lymph node (8/9) tissues were identified as cytotoxic silica dioxide polymorphs. Lung and liver tissue from affected horses had elevated levels of elemental silicon. Osteoporosis was highly correlated (r = 0.8, P < .01) with silicosis. No abnormalities in heavy metal or trace minerals were detected. This evaluation indicated that horses with bone fragility disorder have systemic osteoporosis associated with fibrosing pulmonary silicosis. The etiopathogenesis of the bone fragility syndrome is unknown; however, this study provides circumstantial evidence for a silicate associated osteoporosis.

Topics: Animals; Bone and Bones; Bone Diseases, Metabolic; California; Female; Horse Diseases; Horses; Lung; Lymph Nodes; Male; Osteoporosis; Silicon; Silicosis

Topics: Air Pollutants, Occupational; Dose-Response Relationship, Drug; Dust; Humans; Occupational Exposure; Silicon; Silicosis; United States

To investigate the association between decline in lung function and production of alloys in the Norwegian smelting industry.. All employees (N = 3924) were examined annually for 5 years (16,570 examinations). The employees were classified into three categories: 1) line operators (employed full time in the production line), 2) nonexposed (no exposure last year), and 3) non-line operators (remaining subjects). The outcome variable was expressed as forced expiratory volume in 1 second per squared height (FEV1/height(2)).. In the subcohorts of the ferrosilicon/silicon metal and silicon carbide industries, the differences between line operators and nonexposed workers were -2.3 (-4.3 to -0.3) (CI = 95%) and -5.6 (-10.4 to -0.7) mL/(m(2) x year), respectively.. Line operators in the ferrosilicon/silicon metal and silicon carbide industries had a steeper annual decline in FEV1/height compared with nonexposed workers.

Topics: Adult; Analysis of Variance; Asthma; Carbon Compounds, Inorganic; Case-Control Studies; Cohort Studies; Forced Expiratory Volume; Humans; Male; Metallurgy; Norway; Occupational Diseases; Prospective Studies; Respiration Disorders; Silicon; Silicon Compounds; Silicosis; Smoking

To investigate if there are dust particles in the cells of granulomas of sarcoidosis and analyze its composition and the possible correlation between the sarcoidosis and the composition of dust particles.. The samples of 50 patients with sarcoidosis and 6 patients with silicosis as control were collected by biopsy and/or autopsy sampling. The pathological varieties of the granulomas and the situation of the dust particles within the cells of granulomas were observed using hematoxylin and eosin staining, Warthin-Starry silver staining, immunohistochemistry staining as well as the transmission electron microscope, and the X-Ray spectrum chemical element analysis in the samples from these two kinds of diseases.. The dust particles containing silicon as the main chemical element were present in epithelioid cells and multinucleate giant cells in all the samples. The quantity of the particles deposited in sarcoidosis was less than that in the silicosis. Moreover, the dust cells were found in the granulomas and the visceral pleural lymphatic vessels in the pleura and the hilar pulmonary lymph nodes in sarcoidosis and silicosis. The pathological varieties of the granulomas in sarcoidosis and silicosis were similar.. There are less silicon dust particles in the cells of granulomas of sarcoidosis than in those of the silicotic nodules, which indicates that the silicon dust particles may be related to the sarcoidosis.

Topics: Adolescent; Adult; Aged; Child; Dust; Female; Granuloma; Humans; Male; Middle Aged; Sarcoidosis; Silicon; Silicosis

The role of silicosis as either a necessary or incidental condition in silica associated lung cancer remains unresolved. To address this issue a cohort analysis of dose-response relations for crystalline silica and lung cancer mortality was conducted among diatomaceous earth workers classified according to the presence or absence of radiological silicosis.. Radiological silicosis was determined by median 1980 International Labour Organisation system readings of a panel of three "B" readers for 1809 of 2342 white male workers in a diatomaceous earth facility in California. Standardised mortality ratios (SMR) for lung cancer, based on United States rates for 1942-94, were calculated separately for workers with and without radiological silicosis according to cumulative exposures to respirable crystalline silica (milligrams per cubic meter x years; mg/m3-years) lagged 15 years.. Eighty one cases of silicosis were identified, including 77 with small opacities of > or = 1/0 and four with large opacities. A slightly larger excess of lung cancer was found among the subjects with silicosis (SMR 1.57, 95% confidence interval (CI) 0.43 to 4.03) than in workers without silicosis (SMR 1.19, 95% CI 0.87 to 1.57). An association between silica exposure and lung cancer risk was detected among those without silicosis; a statistically significant (p = 0.02) increasing trend of lung cancer risk was seen with cumulative exposure, with SMR reaching 2.40 (95% CI 1.24 to 4.20) at the highest exposure level (> or = 5.0 mg/m3-years). A similar statistically significant (p = 0.02) dose-response gradient was observed among non-silicotic subjects when follow up was truncated at 15 years after the final negative radiograph (SMR 2.96, 95% CI 1.19 to 6.08 at > or = 5.0 mg/m3-years), indicating that the association among non-silicotic subjects was unlikely to be accounted for by undetected radiological silicosis.. The dose-response relation observed between cumulative exposure to respirable crystalline silica and lung cancer mortality among workers without radiological silicosis suggests that silicosis is not a necessary co-condition for silica related lung carcinogenesis. However, the relatively small number of silicosis cases in the cohort and the absence of radiographic data after employment limit interpretations.

Topics: Adult; Aged; California; Cohort Studies; Dust; Humans; Lung Neoplasms; Male; Middle Aged; Occupational Exposure; Silicon; Silicosis

Up-to-date crystalline silicon production is characterized by such leading occupational hazards as higher level of dust with complicated chemical composition, aerosols that vary with technology and derive from disintegration of silica, crystalline silicon or condensation of silica. Experiments comparing prevalence of diseases caused by silica and crystalline silicon dusts in acute and chronic intratracheal administration and inhalation identified crystalline silicon as moderately fibrogenic and specified its MAC at 4 mg/m3 in the air of workplace.

Topics: Chemical Industry; Dust; Humans; Occupational Exposure; Russia; Silicon; Silicosis

Our study investigated the presence, type and quantity of silicon in the human cornea. We report the results of silicon measurements in the corneas of silicotic individuals, bricklayers and apparently normal human individuals and offer a hypothesis for the mechanism of silicon deposition in the human cornea.. We examined corneas from 13 decreased subjects who suffered from silicosis, 2 bricklayers and 6 apparently healthy subjects. Cornea samples were examined by energy-dispersive x-ray analysis (EDXA) under calibrated conditions in a scanning electron microscope (SEM). The EDXA detector was a silicon-free germanium crystal. Five distinct layers (epithelium, Bowman's membrane, central stroma. Descemet's membrane and endothelium) were analyzed in each cornea. The method allows simultaneous semiquantitative analysis of, among other elements, silicon, calcium and oxygen. We measured amorphous silicon and visible particles of silicon.. We found amorphous silicon in low concentrations in 38% of the silicotic corneas and in very low concentrations in 29% of the healthy corneas. Bricklayers showed high concentrations of amorphous silicon. These accumulations of silicon were predominantly located in Descemet's membrane. Silicotic corneas showed significantly more silicon-containing particles than corneas of healthy controls (chi 2-test, P < 0.01).. Normal corneas contain very low amounts of silicon. Longterm exposure to inhalative silicon dusts results in only very slightly increased levels of amorphous silicon in the cornea. However, silicon-containing particles accumulate in the cornea of silicotic individuals. Bricklayers incorporate more amorphous silicon into the cornea.

Topics: Aged; Aged, 80 and over; Calcium; Cornea; Corneal Diseases; Electron Probe Microanalysis; Female; Humans; Magnesium; Male; Microscopy, Electron, Scanning; Middle Aged; Occupational Diseases; Occupational Exposure; Phosphorus; Silicon; Silicosis

Two cases of extrathoracic silicosis in buffaloes raised near a quartz quarry and suffering from clinically severe silicosis are described. The extrapulmonary changes were characterized by silicoconiotic nodules in the tonsils, mesenteric lymph nodes and spleen. A combination of energy dispersive X-ray microanalysis and scanning electron microscopy revealed that the mineral component of these lesions consisted mainly of silicon, aluminium, iron, calcium, magnesium, zinc, sulphur and potassium. It is concluded that domestic animals raised in polluted environmental conditions represent an important biological source from which helpful data may be obtained for assessing risks to human health and gaining new insight into pathogenetic mechanisms.

Topics: Animals; Buffaloes; Electron Probe Microanalysis; Lymph Nodes; Lymphatic Diseases; Macrophages; Microscopy, Electron, Scanning; Palatine Tonsil; Silicon; Silicosis; Spleen

We report a case of a 35 year-old-man with dermatomyositis associated with tracheopathia osteoplastica. The swallowing perturbation secondary to myositis and airway involvement by tracheopathia induced fatal outcome. Tracheopathia osteoplastica is a rare disease and occurs exclusively in men over the age of 50. The association of two rarest disease is not a fortuitous event. The common pathogenic factor may be, in this case, the occupational exposure to silicon.

Topics: Adult; Age Factors; Airway Obstruction; Bronchial Diseases; Dermatomyositis; Humans; Male; Ossification, Heterotopic; Sex Factors; Silicon; Silicosis; Tracheal Diseases

To evaluate the possibility of quantifying alveolar dust burden in conditions of exposure to silica, four groups of subjects were submitted to bronchoalveolar lavage (BAL): 10 healthy control subjects and 39 patients affected by diffuse interstitial lung disease (DILD) never exposed to dust, 23 silicotic patients and 12 chronic bronchitis patients with a history of occupational exposure to silica dust. Five to ten million BAL recovered cells were analysed with an energy-dispersive X-ray microanalysis (EDXA) system to determine the silicon content, expressed in a semi-quantitative way as silicon to sulphur (Si/S) ratio. The results were independent of smoking habit. The Si/S median values (interquartile range in brackets) for the four groups were 0.53 (0.5-0.65), 0.60 (0.41-0.8), 1.23 (1.06-1.39), 1.31 (1.11-1.97), respectively. Silicotics and simply exposed individuals did not show a significant discrepancy, but they were both significantly different in comparison with normal and DILD patients without history of exposure (p less than 0.001). 14.3% false negative cases were found, and 4.1% false positive cases (none among normal subjects). We did not see any significant relationships between the amount of silicon and the duration of exposure or the degree of chest X-ray involvement. A study of cytocentrifuge slides from the same subjects by polarizing light microscopy revealed a lower sensitivity (34% false negative cases).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Bronchitis; Bronchoalveolar Lavage Fluid; Electron Probe Microanalysis; Female; Humans; Male; Microscopy, Polarization; Middle Aged; Occupational Exposure; Pulmonary Fibrosis; Silicon; Silicosis; Smoking; Time Factors

Two hundred and sixty seven workers employed in the manufacture of silicon carbide (SiC) were examined to determine the effects of exposure to contaminants (SiC, quartz, and SO2) in the workplace on pulmonary function. No exposure concentrations exceeded the current permissible limits. Ten subjects (3.7%) showed rounded opacities (profusion greater than or equal to 1/0). Two subjects employed only in the final stages of the production process and not exposed to crystalline silica showed opacities (profusion q1/0 and q2/1) on x ray film suggesting a role of SiC in the genesis of interstitial lung disease. Chest abnormalities on x ray film were correlated with cumulative exposure to dust and pulmonary function was affected by cumulative dust exposure, profusion of opacities, and smoking. It is concluded that the current standards do not provide adequate protection against pneumoconiosis and chronic pulmonary disease in this industry.

Topics: Carbon; Carbon Compounds, Inorganic; Forced Expiratory Volume; Humans; Lung; Middle Aged; Occupational Exposure; Radiography; Silicon; Silicon Compounds; Silicosis; Vital Capacity

Topics: Glomerulonephritis; Humans; Male; Middle Aged; Silicon; Silicosis

Interstitial lung disease and airflow limitation have been reported in silicon carbide workers but it is uncertain whether these recent observations reflect past working conditions alone (30 years ago) or both past and present conditions even if the latter have improved. To investigate this, we analyzed pairs of chest radiographs obtained in 1977 and 1984 in 128 silicon carbide plant workers. Three indices, related to density of small opacities, profusion of opacities, and presence of pleural plaques, were obtained. Student t-tests on results obtained in each time period showed the mean density (1.02 in 1977 and 0.56 in 1984) and profusion (4.27 in 1977 and 2.13 in 1984) indices to be significantly different. However, the pleural plaque index was not different in 1984 (0.34) as compared with 1977 (0.32). There was no deterioration of the radiographic image even in groups with density ratios equal or greater than 1/1. We concluded that the actual environmental working conditions did not influence the integrity of the lung radiographic image in these workers within a time span of 6 or 7 years.

Topics: Adolescent; Adult; Aged; Air Pollutants, Occupational; Carbon; Carbon Compounds, Inorganic; Child; Humans; Middle Aged; Observer Variation; Radiography; Silicon; Silicon Compounds; Silicosis; Time Factors

A siliceous pneumoconiosis was detected in two dogs by light microscopical, transmission electron microscopical and elemental analysis methods. Aluminium and silicon were the predominant elements and were present in macrophages associated with airways and vessels. The significance and origin of the deposits are discussed.

Topics: Aluminum; Animals; Crystallization; Dog Diseases; Dogs; Electron Probe Microanalysis; Female; Lung; Lymph Nodes; Macrophages; Microscopy, Electron; Silicon; Silicosis

Carborundum is a synthetic abrasive manufactured through fusion of high grade silica sand and finely ground carbon in an electric furnace at 2,400 degrees C. It had been considered an inert dust until recently. Two recent epidemiologic studies in Quebec have documented an excess of interstitial lung disease in plant workers and some 30 workers have received workman compensation. Histopathologic lesions have been described in four of the workers. To further investigate the carborundum pneumoconiosis, nine groups of eight sheep were exposed once in the tracheal lobe to either 100 ml saline, 100 mg latex beads in 100 ml saline, 100 mg graphite in 100 ml saline, 100 mg carborundum particles in 100 ml saline, 100 mg ashed carborundum particles in 100 ml saline, 100 mg of quartz (Minusil-5) in 100 ml saline, 100 mg crocidolite fibers in 100 ml saline, 100 mg carborundum fibers in 100 ml saline, and 100 mg ashed carborundum fibers in 100 ml saline solutions. The animals had BAL at two-month intervals and autopsy at month 8. The BAL analyses of cellularity, cytotoxicity and fibrogenicity, in association to necropsy histopathology, documented that all particles except for quartz were inert. The two-carborundum fiber samples produced a similar sustained nodular fibrosing alveolitis and crocidolite asbestos fibers produced a peribronchiolar fibrosing alveolitis of comparable severity. Thus, the major bioactive dusts in the carborundum manufacturing process are quartz particles and the carborundum fibers generated in the process. The latter have fibrogenic activities comparable to asbestos fibers of similar size and are likely to contribute to the pathogenesis of the interstitial lung disease of carborundum workers.

Topics: Animals; Bronchoalveolar Lavage Fluid; Carbon; Carbon Compounds, Inorganic; Fibroblast Growth Factors; Humans; Lung; Macrophage Activation; Sheep; Silicon; Silicon Compounds; Silicosis

Topics: Aged; Aged, 80 and over; Carcinoma, Bronchogenic; Diagnosis, Differential; Humans; Lung; Lung Neoplasms; Male; Silicon; Silicosis

Lung tissue of a worker in an abrasive manufacturing plant, whose duration of dust exposure was about 10 years, was analyzed by means of bulk analysis and in situ analytical electron microanalysis. The content of the total dust in the lung was 120 mg/g of the dried lung tissue. This value is close to the average concentration of the total dust in the lungs of coal miners with massive fibrosis. The lung dust composition in this case was approximately 43% silicon carbide, 24% aluminium oxide, 2.3% cristobalite, 2.0% quartz, and trace of talc and feldspar. Silicon carbide may be one of the major etiologic agents in this case of pneumoconiosis.

Topics: Adult; Carbon; Carbon Compounds, Inorganic; Dust; Electron Probe Microanalysis; Humans; Lung; Male; Microscopy, Electron; Particle Size; Silicon; Silicon Compounds; Silicosis

Rats were intratracheally instilled with 50 mg of size-fractionated crystalline quartz to induce silicosis. Lungs were analyzed 1, 4, 6, and 9 months after instillation for their content of the reduced difunctional collagen crosslinks dihydroxylysinonorleucine (DHLNL) and hydroxylysinonorleucine (HLNL), of the nonreducible trifunctional (mature) crosslink, hydroxypyridinium (OHP), and of hydroxylysine. Ratios of DHLNL: HLNL were elevated in silicotic lung collagen at all times sampled, due both to increased levels of DHLNL and decreased amounts of HLNL. Hydroxylysine content of collagen in the silicotic lungs was also increased as compared with age-matched control rats. Hydroxypyridinium content of silicotic lung collagen was less than control values at 1 month, but was significantly increased to about 120%, 150%, and 175% of the age-matched control values at 4, 6, and 9 months after silica instillation, respectively. The increased levels of OHP in lung collagen were temporally correlated with the appearance of mature silicotic nodules in these lungs. We conclude that the large amounts of excess collagen deposited in silicotic lungs differs biochemically from normal lung collagen despite maintenance of the normal ratio of major collagen types in silicotic lungs.

Topics: Amino Acids; Animals; Chromatography, High Pressure Liquid; Collagen; Dipeptides; Hydroxylation; Lung; Protein Binding; Rats; Rats, Inbred Strains; Silicon; Silicosis; Time Factors

Current methods for determining the fibrogenicity of substances are based on relatively long term exposures of animals to the substance and the evaluation of morphological changes occurring in the lung. The use of inhalation chambers, which produce a more physiological environment, suffer from the need for particularly long exposure times (1-3 years). The present study describes a technique using scanning electron microscopy, energy dispersive analysis, and a digitiser pad with a computer to evaluate the fibrogenicity of silica in cases of known exposure. Scanning electron micrographs taken from silicotic lungs were evaluated for the degree of thickening (fibrosis) and the same areas were analysed for silicon content. Correlations between silicon content and septal thickening were shown to be significant (p less than 0.0001). The study also describes the concentrations of elements found in normal lungs. The technique for establishing correlation curves between elemental concentrations and septal thickening could be of value in determining the fibrogenicity of pure substances after short exposures in an environmental chamber.

Topics: Aluminum; Electron Probe Microanalysis; Elements; Humans; Lung; Magnesium; Microscopy, Electron, Scanning; Pulmonary Fibrosis; Reference Values; Silicon; Silicosis

Pulmonary specimens obtained from ten normal subjects and 53 patients with various pulmonary diseases were studied with energy-dispersive x-ray analysis. The amount of silicon in the pulmonary tissue was determined and expressed as a silicon/sulfur (Si/S) ratio. This Si/S ratio was below 0.2 in the ten normal subjects and in 14 patients who had various interstitial pulmonary diseases but had no previous history of exposure to silica or other dusts known to cause pulmonary fibrosis. The Si/S ratio was greater than 0.3 in 19 of 22 patients who had a history of exposure to silica dust and had clear-cut histologic evidence of silicosis. The Si/S ratio was less than 0.2 in 12 and between 0.2 and 0.3 in two of the 14 patients who had a history of exposure to silica dusts but no clinical or histologic evidence of silicosis. We conclude that the determination of the silicon content of tissue by energy-dispersive x-ray analysis is useful in separating the fibrosis due to silicosis from the other causes of pulmonary fibrosis.

Topics: Adult; Aged; Electron Probe Microanalysis; Humans; Lung; Male; Middle Aged; Pulmonary Fibrosis; Radiography; Silicon; Silicosis; Sulfur

Topics: Animals; Bone and Bones; Carbon; Humans; Phospholipids; Polysaccharides; Proteins; Silicic Acid; Silicon; Silicosis

Topics: Animals; Antigens, Bacterial; Body Weight; Dust; Environmental Exposure; Escherichia coli; Female; Hemolytic Plaque Technique; Immunity; Lung; Mice; Mice, Inbred BALB C; Silicon; Silicosis; Spleen

Decreased ribonuclease activity in the supernatant from silica-treated macrophages is associated with the enhanced protein synthesis in granulation-tissue slices incubated in this supernatant, and with the decreased degradation of polysomes in granuloma slices and of polysomes isolated from the granulation tissue. The phagocytized silica particles adsorb ribonuclease and perhaps other proteins and thus remove them from the macrophage supernatant.

Topics: Animals; Female; Fibroblasts; In Vitro Techniques; Macrophages; Polyribosomes; Protein Biosynthesis; Rats; Ribonucleases; Silicon; Silicosis

X-ray images can be formed in a conventional scanning electron microscope equipped with a Si(Li) energy dispersive spectrometer. All the x-ray events generated in the electron beam scanning process are synchronously displayed in the same manner as for dot maps. The quasi-digital image formed using Total Rate Imaging with X-rays (TRIX) exhibits good gray scale contrast and is dependent on topography, orientation and atomic number. Although this latter dependence is complex, it has been found useful in locating several types of inclusions in lung tissue (silicosis), human alveolar macrophages and cigarette smoke condensate. This is because of the greater depth of penetration of x-rays than backscattered electrons (BSE) usually used for such localizations in a matrix, and the negligible sensitivity of the Si(Li) detector to x-rays from an organic biological matrix. The optimum procedure is to use a combination of TRIX and BSE to investigate such specimens.

Topics: Electron Probe Microanalysis; Humans; Lung; Macrophages; Microscopy, Electron, Scanning; Nicotiana; Plants, Toxic; Scattering, Radiation; Silicon; Silicosis; Smoke; X-Rays

The elemental content of alveolar septa in various pneumoconioses was examind for a possible relationship to interstitial fibrosis. Silicon content, as well as heavy metal content, were evaluated to deterrmine possible interrelationships between the various inorganic dusts. Silicon levels were determined on the basis of silicon-sulphur ratios to accommodate for differences in tissue mass. A study of the variation of silicon-sulphur ratios in silicotics and normal individuals showed no false positives by our diagnostic criteria. A study of 11 cases of siderosis revealed that silicon was not responsible for the fibrosis as previously believed. An analysis of the lungs of 25 non-silicotic fibroses revealed that silicon-sulphur ratios were within normal limits. This technique should be useful in quantitating high exposure to certain dusts and in studying the relationship of such dusts to fibrosis.

Topics: Electron Probe Microanalysis; Humans; Macrophages; Pneumoconiosis; Pulmonary Alveoli; Pulmonary Fibrosis; Silicon; Silicosis; Sulfur

Topics: Adult; Dust; Electromyography; Humans; Male; Middle Aged; Occupational Diseases; Partial Pressure; Respiration; Silicon; Silicosis; Vibration

Abnormal numbers of birefringent particles have been found in the lungs of seven patients (five vineyard workers, one farmer, and one rural resident) in association with a spectrum of early to late interstitial inflammation and fibrosis. Nodular granulomas of the type seen in silicosis were absent. Scanning electron microscopy and energy dispersive x-ray analysis of 177 individual particles (less than 5 micrometer.) in situ in the lungs of four of the patients showed mostly silicates (notably aluminum, silicon, and potassium), with 5 to 10 per cent silicon dioxide. An analysis of particles less than 5 micrometer. from both vineyard and non-vineyard soil showed lung and soil particles to have a similar composition. The presence of large amounts of silicates in the lung tissues, in association with chronic inflammation and fibrosis, implicates the silicates in the causation of the fibrosis. The silicate deposits may, in large part, be a marker, reflecting a mixture of toxic soil additives or pesticides found in commercial clay silicate products or in dusts from the soil itself. The findings do not exclude lung pathology of a similar nature in regions outside of the farm.

Topics: Aged; Agricultural Workers' Diseases; Birefringence; Female; Humans; Male; Microscopy, Electron, Scanning; Middle Aged; Pulmonary Fibrosis; Silicon; Silicosis; Soil; X-Rays

We found three cases of pneumoconiosis among those workers who had been dealing with tonoko (a mineral powder) for more than ten years at a shop making wooden furniture in Sendai, Japan. In the factory the workers were exposed to tonoko dust and had been inhaling it for a long time. Until now, this disease has not been found in employees of furniture factories; and, furthermore, tonoko has not been regarded as a harmful material. Tonoko is a very fine mineral powder used widely in Japan for filling the grains of surfaces of wooden products. The three workers had scanty clinical symptoms; however, their chest x-ray films revealed disseminated nodulations throughout both pulmonary fields. One of the workers suffered from the complication of active pulmonary tuberculosis. Some of the analyses revealed that tonoko contained about 50% quartz. Accordingly, the disease is strongly suspected to be a sort of silicosis caused by inhalation of tonoko dust.

Topics: Airway Resistance; Aluminum Oxide; Female; Ferric Compounds; Humans; Interior Design and Furnishings; Japan; Lung Compliance; Male; Middle Aged; Pulmonary Diffusing Capacity; Radiography; Respiratory Function Tests; Silicon; Silicosis; Silicotuberculosis

Topics: Animals; Cold Temperature; Dust; Environmental Exposure; Lung; Lymph Nodes; Rats; Silicon; Silicosis; Sodium Chloride

Pulmonary silicosis usually is characterized by typical hyalinized, concentric nodules as seen under the microscope and in the corresponding roentgenogram. In the case of three foundry workers, lung biopsy specimens contained no nodules. The chest roentgenograms were not suggestive of silicosis. Examination of the biopsy tissue by scanning electron microscopy and energy dispersive x-ray analysis (EDXA) revealed significant (P less than .05) amounts of silicon in the thickened fibrous tissues of septa, pleura, and around blood vessels, enough to permit the diagnosis of silicosis. All three patients had severe functional impairment. It is not clear at this time what factors were responsible for a diffuse distribution of silicon in these cases.

Topics: Humans; Lung; Male; Middle Aged; Occupational Diseases; Silicon; Silicosis; Sulfur

Topics: Activation Analysis; Adolescent; Adult; Aged; Aluminum; Child; Coal Mining; Female; Humans; Infant; Lymph Nodes; Male; Middle Aged; Phosphorus; Silicon; Silicosis; Spectrometry, Gamma

Topics: Computers; Electronic Data Processing; Environmental Exposure; Mining; Occupational Diseases; Registries; Silicon; Silicosis; Sweden

Topics: Animals; Asbestosis; Guinea Pigs; Humans; Lipids; Macrophages; Magnesium; Microscopy; Microscopy, Electron, Scanning; Osmium; Pulmonary Alveoli; Silicon; Silicosis; Spectrophotometry

Topics: Aluminum; Animals; Asbestos; Asbestosis; Carbon; Carbon Compounds, Inorganic; Dust; Environmental Exposure; Lung; Rats; Silicon; Silicon Dioxide; Silicosis; Time Factors

Topics: Adult; Construction Materials; Dust; Female; Humans; Oxides; Silicon; Silicosis; USSR

Topics: Adult; Explosions; Granuloma; Humans; Male; Purpura; Silicon; Silicosis; Skin Diseases; Skin Neoplasms

Topics: Environmental Exposure; Environmental Pollution; Health Surveys; Humans; Methods; Occupational Diseases; Occupational Medicine; Protective Devices; Registries; Sampling Studies; Silicon; Silicosis; Sweden

Topics: Altitude; Dust; Humans; Maximum Allowable Concentration; Mining; Peru; Silicon; Silicosis

Topics: Aged; Alloys; Autopsy; Diagnostic Errors; Follow-Up Studies; Humans; Iron; Male; Metallurgy; Norway; Radiography; Silicon; Silicosis; Sweden; United States

Topics: Animals; Cobalt; Copper; Dust; Humans; Iron; Rats; Silicon; Silicosis

Topics: Adult; Air Pollution; Dust; Humans; Iron; Male; Metallurgy; Middle Aged; Occupational Diseases; Silicon; Silicon Dioxide; Silicosis

Topics: Activation Analysis; Aluminum; Cadmium; Humans; Lymph Nodes; Phosphorus; Silicon; Silicosis; Spectrophotometry

Topics: Adult; Aged; Humans; Lung; Lymph Nodes; Magnesium; Middle Aged; Mining; Silicon; Silicosis; Titanium; Zinc

Topics: Animals; Lung; Male; Oxides; Properdin; Rats; Silicon; Silicosis

Topics: Female; Humans; Mining; Silicon; Silicosis; Time Factors; Tuberculosis, Pulmonary

Topics: Animals; Rats; Silicon; Silicosis

Topics: Adsorption; Blood Proteins; Chemical Phenomena; Chemistry; Humans; Hydroxides; In Vitro Techniques; Proteins; Silicon; Silicon Dioxide; Silicosis

Topics: Adult; Aged; Autopsy; Bone Marrow; Humans; Lung; Middle Aged; Occupational Diseases; Silicon; Silicosis; Silicotuberculosis

Topics: Chemical Phenomena; Chemistry; Diagnosis, Differential; Humans; Silicon; Silicosis; Sputum; Tuberculosis, Pulmonary

Topics: Ceramics; Chemical Industry; Environmental Exposure; Humans; Italy; Radiography, Thoracic; Silicon; Silicosis

Topics: Alloys; Animals; Chromium; Dust; Iron; Lung; Rats; Silicon; Silicosis

Topics: Animals; Dust; Environmental Exposure; Lipid Metabolism; Lung; Metallurgy; Occupational Medicine; Proline; Rats; Silicon; Silicosis

Topics: Coal Mining; Germany, West; Humans; Luminescent Measurements; Occupational Diseases; Silicon; Silicosis; Silicotuberculosis

Topics: Humans; Silicon; Silicon Dioxide; Silicosis

Topics: Blood Chemical Analysis; Humans; Silicon; Silicosis

Topics: Animals; Diathermy; Lung; Lymph Nodes; Rats; Silicon; Silicosis

Topics: Animals; Benzopyrenes; Lung Neoplasms; Rats; Silicon; Silicosis

Topics: Dust; Respiratory Function Tests; Silicon; Silicosis

Topics: Aerosols; Calcium; Calcium, Dietary; Dust; Fluorides; Rats; Research; Silicon; Silicosis

Topics: Czechoslovakia; Dust; Eye Manifestations; Granuloma; Iron; Rabbits; Research; Silicon; Silicosis

Topics: Adenine Nucleotides; Animals; Dextrans; Edema; Oligoribonucleotides; Rats; Silicic Acid; Silicon; Silicosis

Topics: Connective Tissue; Humans; Silicon; Silicosis

Topics: Adenine Nucleotides; Muscle Contraction; Muscles; Oligoribonucleotides; Silicon; Silicosis

Topics: Polymerization; Silicic Acid; Silicon; Silicosis

Topics: Ceramics; Dust; Employment; Humans; Silicon; Silicon Dioxide; Silicosis

Topics: Humans; Plasma; Silicic Acid; Silicon; Silicosis

Topics: Connective Tissue; Silicic Acid; Silicon; Silicosis