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PubMed1990

[The epidemiology of silicosis in the El Escorial region].

In a sample of 186 stone workers who performed granite "tearing" and "stone work" (either manual or mechanical) we have found silicosis in 50.5% (simple silicosis 47.3%, and complicated silicosis 3.2%). The most commonly found radiologic manifestation was a round opacity type "p" and a 1/1 to 1/3 profusion. From a functional respiratory perspective, a mild reduction of FVC, DLco (SB) and pO2 similar to that described in coal miners' pneumoconiosis was observed. It seems that "stone workers" had a higher incidence of suffering severe silicosis than stone "tearing" workers. Surprisingly, in the analysis of inhaled dust of such an activity which is performed in the open air the rates of dust and SiO2 are much higher than those found in coal workers. We believe that this is the first time that these measurements are performed, and published, in a group of stone workers.

Humans↗

PubMed1978

Silicosis in diatomaceous earth factory workers in Sweden.

Kieselguhr is a greyish-white powder which is made by heating lake ooze containing diatom skeletons to a temperature of about 1000 degrees C. It contains quartz, cristobalite and tridymite. Working with kieselguhr can induce silicosis. In Sweden six cases of silicosis caused by exposure to kieselguhr have been reported to the Worker's Protection Board. The time of exposure was relatively short. New cases have not appeared in the last 20 years. It seems, nevertheless, important to document this unusual form of silicosis, as diatomaceous earth is readily available and the manufacturing process is simple. Demand for kieselguhr has increased and new factories are to be established which may result in new cases of silicosis.

Adult↗

PubMedDate not supplied

The principles of predicting the individual risk of silicosis and silicotuberculosis.

A series of investigations conducted in different "silicosis-risk" industries using a methodology based on the mathematical theory of pattern recognition has shown that in the given conditions of dust exposure, the probability of contracting pneumoconiosis depends for each individual on a complex influence of many factors, both environmental and intrinsic for the individual. Genetic predisposition was one of the most important factors and while the direction in which a factor influences predisposition was the same in every industry, its relative contribution to predisposition to simple silicosis was different in the studied working populations. So a reliable prediction of the high probability of this form of pneumoconiosis on the basis of such a multifactorial analysis is possible only with respect to specific conditions of a particular industry. The complex of factors determining predisposition to silicotuberculosis is more general: this complex comprises both factors influencing susceptibility to silica dust and specially those influencing susceptibility to tuberculosis. Despite the low prevalence of genetic resistance to pneumoconiosis in working populations, the risk of contracting the disease in modern industrial conditions of relatively low dust exposure is high only for a proportion of workers for whom the genotype of predisposition to silicosis or to silicotuberculosis coincides with a most unfavourable combination of non-genetic factors enhancing this predisposition. In the opinion of the authors, the task of screening off those applicants for a "silicosis-risk" employment for whom the risk may be estimated as high on the basis of the developed methodology, is quite feasible.

Discriminant Analysis↗

PubMed1977

[Clincial aspects and treatment of exacerbated chronic respiratory insufficiency in silicosis patients].

The clinical picture and treatment of exacerbated chronic respiratory insufficiency is studied in 189 silicosis patients with different stage and degree of decompensation. It is found out that chronic respiratory insufficiency determination in these patients is conditioned by the exacerbation of a chronic inflammtory process in the bronchi and lungs (68.2 per cent), or by intercurrent acute inflammtory pulmonary process (15.9 per cent). The clinical manifestation of the disease is aggravated and modified by the appearance of new clinical elements, resulting in the typical clinical picture of inflammatory decompensation of silicosis. It is stressed that the effect of treatment is greater, the milder the stage of the disease, and the earlier and less marked the decompensation-induced derangements. Lethality in patients with III degree silicosis amounts to 8,2 per cent, and in patients with III degree respiratory insufficiency -- to 30.7 per cent. A complex active therapy program for silicosis patients with exacerbated chronic respiratory insufficiency is proposed.

Chronic Disease↗

PubMed1978

Cellular and humoral hypersensitivity reactions during silicosis and silicotuberculosis.

Together with the synthesis of specific antibodies and autoantibodies, effects of cellular allergy, such as damage to neutrophils, agglomeration of leukocytes and inhibition of migration of leukocytes with tuberculin and isologous pulmonary antigen were established in patients with silicosis and silicotuberculosis. Autoallergy becomes manifest already in the "pre-roentgenological" stage of development of silicosis; in silicotuberculosis it correlates with the stage of the specific process. In both silicosis and silicotuberculosis, it includes elements of immediate and delayed hypersensitivity. In clinical practice, allergic reactions of leukocytes with tuberculin can be of assistance in determining the stage of the specific process and in differential diagnosis of silicosis and silicotuberculosis.

Antibody Formation↗

PubMedDate not supplied

[Silicosis and bronchial cancer (author's transl)].

1. At world level, silicosis does not predispose to bronchial cancer. But from region to region, the relationship silicosis-cancer varies and depends on factors other than silica. 2. It has not been proved that silica is cancerigen in laboratory animal. 3. Subjects exposed to silica can also be exposed in other circumstances to known carcerigen agents (ionizing radiations, iron oxides, arsenic, exhaust gases of explosion engins). In Switzerland, it is possible that miners in galeries could breath low concentrations of radon and benzopyrene. But it is very difficult to know to what extent these potential risks are involved. 4. Bronchial carcinoma in silicotic patients does not own any characteristics. It is quite similar to that found in the remainder of the population. On the other hand, its diagnosis and treatment are more difficult because of the presence of silicosis. 5. The fortuitous association of silicosis and bronchial cancer is due to overlapping of the profiles of both diseases. The increasing life span of the silicotic patient and the high frequency of bronchial cancer explain why this association is not more exceptional.

Animals↗

PubMed1994

The effects of tetrandrine (TT) and polyvinylpyridine-N-oxide (PVNO) on gene expression of type I and type III collagens during experimental silicosis.

In the screening tests of drugs for silicosis in our laboratory, we found that TT, a type of alkaloid isolated from Stephania tetrandra, could inhibit the development of experimental silicosis of rats and the synthesis of collagen in rat lung. Chest X-rays of silicotic patients treated with TT for 1-3 years showed obvious changes. The silicotic nodules became smaller and shadows became clearer. PVNO was proved to have anti-silicotic effect on animal and clinically. This presentation reports the effect of them on collagen mRNA. Dot blot results showed that alpha 1 (I) and alpha 1 (III) mRNA levels increased significantly at 60 and 120 days after the rats were exposed to silica dust. The mRNA levels went down at 1 and 3 months after treated by TT and PVNO. In situ hybridization observation revealed that the silver grains of Type I and Type III collagen were scattered within the fibroblasts in cellular nodules and in thickened interstitium of silicosis tissue. The amounts of mRNA silver grains decreased in the lung tissue treated by TT and PVNO. It was suggested that TT and PVNO may inhibit the gene expression of collagen during silicosis.

Alkaloids↗

PubMedDate not supplied

Patterns of secretion of transforming growth factor-alpha (TGF-alpha) in experimental silicosis. Acute and subacute effects of cristobalite exposure in the rat.

Transforming growth factor-alpha (TGF-alpha) a cytokine having potent mitogenic activity for epithelial and mesenchymal cells, may play a role in the lung remodeling of silicosis. Lung macrophages are among the major cells producing TGF-alpha in a lung tissue. A pivotal event in the cascade of pathologic events leading to pulmonary silicosis is the interaction between inhaled silica and macrophages. TGF-alpha may be critical in directing the proliferation of type II pneumocytes that characterize silicosis. An inhalation model of brief exposure of pathogen-restricted male rats to 25 mg/M3 cristobalite, a highly reactive form of silicon dioxide was used to study experimental silicosis. This model is characterized by a rapid, intense, and sustained increase in macrophages, neutrophils, and lymphocytes in both alveolar and interstitial compartments of the lung. TGF-alpha was measured in an A431 cell proliferation assay made specific with the use of anti-TGF-alpha neutralizing antiserum in epithelial lining fluid (ELF) and conditioned media harvested from cultured alveolar and interstitial macrophages. Soluble TGF-alpha levels found in ELF were slightly elevated above control values during the exposure period, then increased 5-fold during the 20 weeks after the 8-day exposure period. Secretion of TGF-alpha by macrophages was elevated during exposure to cristobalite but then fell during the early post exposure period. Marked elevations in TGF-alpha secretion from both interstitial and alveolar macrophages (10- and 12-fold, respectively) occurred 8-16 weeks after cessation of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1993

[The study of oxidative injury of alveolar macrophage in the development of silicosis].

The changes of oxidant and anti-oxidant system of alveolar macrophage under the influence of quartz were studied from different angles such as in vitro cell test, experimental rat silicosis and patients with silicosis. The results showed that quartz dust could induce the production of oxygen derived free radicals of alveolar macrophages which could lead to lipid peroxidation of cell membrane system. These changes were especially obvious in the early stage of experimental rat silicosis and in the patients with silicosis. The process recycling dust involving ingestion, destruction and re--releasing of the dust by the alveolar macrophages, was an important link in the production and development of lung fibrosis. It also illustrated the role played by oxidative injury of alveolar macrophages in the development of lung fibrosis.

Adult↗

PubMed1995

Silicosis and pulmonary tuberculosis in stone-grinding factories in Saraburi, Thailand.

The stone-grinding industry is well known to place its workforce at higher risk for silicosis. In addition, workers who are exposed to silica fibers are at a higher risk for pulmonary tuberculosis. This study was conducted to determine the prevalence levels of silicosis and pulmonary tuberculosis among workers in 33 factories in 3 subdistricts of Saraburi, Thailand and the associated risk factors. Thirty-one of the factories (93.9%) had amounts of either total dust or respirable dust exceeding threshold limit values with the average levels of total dust and respirable dust of 24.3 +/- 34.6 and 2.4 +/- 1.6 mg/m3 respectively. Radiologic patterns indicated that 61 workers (9.0%) had silicosis and 13 workers (1.9%) had pulmonary tuberculosis. The prevalence of silicosis and pulmonary tuberculosis was significantly associated with years of work. This study demonstrated the need for developing and supporting potential primary preventive intervention, periodic medical screening as a part of a medical surveillance system and a national occupational medical services program.

Adolescent↗

PubMed1995

Incidence of silicosis among ceramic workers in central Italy.

The incidence of radiological silicosis was studied among 2480 male workers employed in the ceramics industry. The subjects entered the surveillance program during 1974-1987 and were followed through 1991 with annual chest radiographs. The cumulative risk of silicosis (1/1 or greater; p,q,r) reached 48% (95% confidence interval 41.5-54.9) after 30 years of employment. In a multivariate Cox's proportional hazards model, the effect of duration of exposure increased linearly up to the category of 25-29 years; an extremely high hazard risk of 14.6 was found among those with 30 years or more of exposure in comparison with those employed 10 years or less. Smoking habit also significantly contributed to the model, although its role in the biological process is unclear. In conclusion, exposure to silica dust has been associated with a high incidence of silicosis among ceramics workers. The risk estimates are consistent with the recent findings of silicosis incidence among South African gold miners.

Adolescent↗

PubMed2004

High prevalence of silicosis among stone carvers in Brazil.

BACKGROUND: In the city of Petrópolis, Brazil, artisans carve souvenirs from a variety of silica-containing minerals. The finding of pulmonary massive fibrosis in one of the workers motivated an investigation of the prevalence of silicosis in this group. METHODS: Between January 2000 and June 2002, a cross-sectional study was performed. We obtained clinical and occupational histories, spirometry, lung volumes, and carbon monoxide diffusion capacity measurements. Chest radiographs and high-resolution computed tomographies (HRCT) were evaluated. Personal air samples were analyzed. RESULTS: Forty-two stone carvers were examined. The prevalence of silicosis was 53.7%. HRCT better characterized silicotic lesions compared to chest radiographs. Early coalescence of small opacities was associated with lung function impairment. The concentration of dust exceeded permissible limits in 91% of the workplaces. CONCLUSIONS: Exposure to high levels of silica dust was associated with an increased prevalence of silicosis among stone carvers. Am. J. Ind. Med. 45:194-201, 2004.

Brazil↗

PubMed2001

Accelerated silicosis in workers exposed to agate dust in Guangzhou, China.

BACKGROUND: An investigation of a small private agate mill was prompted by an agate worker who presented with silicosis in Guangzhou, China, in December 1998. METHODS: The work processes and records of dust measurements of the mill were examined. The mean total dust concentrations ranged from 3.0 to 9.9 mg/m3; 86-88% of the particles' diameter was smaller than 5.0 microm. Free SiO2 content from agate samples was measured. Occupational history was obtained and X-ray chest and lung function was carried out. RESULTS: Free SiO2 content of the agate was 90.5%. Thirty-two men involved in processing agate stone were examined. The mean ( +/- SD) age was 29.8 ( +/- 4.9) years and the mean (+/- SD) duration of exposure was 3.5 (+/- 1.7) years. Fifteen cases (47%) were diagnosed as accelerated silicosis. Up to September 1999, three had died from respiratory failure and five were in critical condition. CONCLUSIONS: Silicosis is an important problem in primitive work environments.

Adult↗

PubMed2005

The cost effectiveness of occupational health interventions: prevention of silicosis.

BACKGROUND: The failure to recognize occupational health as an economic phenomenon limits the effectiveness of interventions ostensibly designed to prevent disease and injury. Hence, consideration of economic efficiency is essential in the evaluations of interventions to reduce hazardous working conditions. In this paper, we present an analysis of the cost effectiveness of alternative means of preventing silicosis. METHODS: To evaluate the cost effectiveness of specific interventions for the prevention of occupationally induced silicosis, we have used the simulation models based on the generalized cost-effectiveness analysis (GCEA) developed by the WHO-CHOICE initiative for two representative subregions namely AMROA (Canada, United States of America), and WPROB1 (China, Korea, Mongolia). RESULTS: In both of the two subregions, engineering controls are the most cost effective with ratios varying from 105.89 dollars per healthy year or disability adjusted life year saved in AMROA to approximately 109 dollars in WPROB1. In the two subregions, the incremental cost-effectiveness ratio of engineering controls (EC) looks most attractive. Although dust masks (DM) look attractive in terms of cost, the total efficacy is extremely limited. CONCLUSIONS: To the extent that this analysis can be generalized across other subregions, it suggests that engineering control programs would be cost effective in both developed and developing countries for reducing silica exposure to save lives. Note that this analysis understates health benefits since only silicosis and not all silica-related diseases are considered.

Adolescent↗

PubMed1990

Mortality of a cohort of men in a silicosis register: further evidence of an association with lung cancer.

Lung cancer mortality from 1980 to 1986 was studied in a cohort of 1,419 men in a silicosis register who had no previous exposure to asbestos and polyaromatic hydrocarbons. The 28 deaths from lung cancer were statistically in excess of expected (SMR 2.03; 95% CI 1.35-2.93). Excess risks of lung cancer were found in both underground workers (SMR 3.41; 95% CI 1.10-7.97; based on 5 deaths) and surface workers (SMR 1.87, 95% CI 1.18-2.81; based on 23 deaths). All lung cancer deaths were smokers. There was an increase in SMRs with longer latency periods and years of exposure, with the greatest risk found in those who had worked for 30 or more years after more than 30 years since first exposed (SMR 3.07, based on 16 deaths). The risk for lung cancer was higher in those with tuberculosis (SMR 2.52; 95% CI 1.52-3.94) and showed an increasing trend with severity of silicosis, from category 1 to 3 and from category A to C, with highest risk in those with tuberculosis and category 3 (SMR 4.44 based on 3 deaths) or tuberculosis and category C (SMR 7.63 based on 7 deaths). Most of the excess lung cancer risk in silicotics is due to smoking, but a synergistic effect between smoking and silica/silicosis on the risk of lung cancer is also likely. In particular, a possible role of silicosis and tuberculosis as the fibrotic seedbed for malignant growth in the lung is strongly supported.

Adult↗

PubMed1986

Red blood cell anti-oxidant parameters in silicosis.

The anti-oxidant phenotype was determined in red blood cells and plasma of a group of male control subjects (n = 48) and a number of silicosis patients (n = 19). Haemoglobin, reduced and oxidized glutathione, glutathione peroxidase and superoxide dismutase were determined in red blood cells after haemolysis. In plasma, water soluble fluorescent substances were determined as a measure of in vivo lipid peroxidation. A significant increase in red blood cell glutathione was observed in silicosis patients. Moreover, some factors of the anti-oxidant system are strongly correlated in the diseased, but not in the healthy subjects. We hypothesize that individual susceptibility differences towards the development of silicosis after prolonged inhalation of silica is associated with a genetically controlled anti-oxidant phenotype.

Aged↗

PubMed1979

Silicosis due to intentional inhalation of abrasive scouring powder. Case report with long-term survival and vasculitic sequelae.

Silicosis due to inhalation of abrasive scouring powder is now an unusual event. We report a nonindustrial case of acute silicosis due to intentional inhalation of commercial, silica-containing scouring powder. This case is unique in that the patient had a 20 year survival (after onset of symptoms) with typical roentgenographic and histopathologic changes of silicosis, and evidence of immune complex disease in extrapulmonary tissues.

Adult↗

PubMedDate not supplied

Lung cancer mortality and silicosis in Québec, 1938-85.

Men who had received compensation for silicosis in Québec between 1938 and 1985 were studied up to the end of 1986 to estimate risk of lung cancer mortality. Particular attention was paid to selection biases inherent in the study of such workers. Age-specific and calendar-year-specific mortality rates of Québec men from 1931 to 1985 were used for comparison. Risk of death from lung cancer in men who had received compensation for silicosis was more than 3 times higher than expected; silicosis may be a strong risk factor for lung cancer mortality.

Bias↗