Selenium and exposure to fibrogenic mineral dust: a mini-review.

Individuals exposed to fibrogenic mineral dust may exhibit an impaired antioxidant system and produce high levels of reactive oxygen and nitrogen species through immune cells, contributing to the perturbation of immune cell function, inflammation, fibrosis and lung cancer. The lung diseases which are caused by inhalation of fibrogenic mineral dust, known as pneumoconioses, develop progressively and irreversibly over decades. At the moment there is no known cure. The trace element selenium has potent antioxidant and anti-inflammatory properties mediated mainly through selenoproteins. Research has demonstrated that selenium has the ability to protect against cardiovascular diseases; to kill cancer cells in vitro and reduce cancer incidence; and to immunomodulate various cellular signaling pathways. For these reasons, selenium has been proposed as a promising therapeutic agent in oxidative stress associated pathology that in theory would be beneficial for the prevention or treatment of pneumoconioses such as silicosis, asbestosis, and coal worker's pneumoconiosis. However, studies regarding selenium and occupational lung diseases are rare. The purpose of this study is to conduct a mini-review regarding the relationship between selenium and exposure to fibrogenic mineral dust with emphasis on epidemiological studies. We carried out a systematic literature search of English published studies on selenium and exposure to fibrogenic mineral dust. We found four epidemiological studies. Reviewed studies show that selenium is lower in individuals exposed to fibrogenic mineral dust. However, three out of the four reviewed studies could not confirm cause-and-effect relationships between low selenium status and exposure to fibrogenic mineral dust. This mini-review underscores the need for large follow-up and mechanistic studies for selenium to further elucidate its therapeutic effects.

Silica dust, radon and death from non-malignant respiratory diseases in German uranium miners.

OBJECTIVE: To quantify the relationship between death from non-malignant respiratory diseases (NMRD) and exposure to silica dust or radon in a cohort of 58,690 former German uranium miners. METHODS: In the follow-up period from 1946 to 2008, a total of 2336 underlying deaths from NMRDs occurred, including 715 deaths from chronic obstructive pulmonary diseases (COPD) and 975 deaths from silicosis or other pneumoconiosis. Exposure to respirable crystalline silica and radon was individually assessed by means of a comprehensive job-exposure matrix. Risk analyses were based on a linear Poisson regression model with the baseline stratified by age, calendar year and duration of employment. RESULTS: There was no increase in risk of death from COPDs or any other NMRDs in relation to cumulative exposure to silica (mean=5.9, max=56 mg/m(3)-years), except in the group of deaths from silicosis or other pneumoconiosis. Here, a strong non-linear increase in risk was observed. Cumulative radon exposure (mean=280; max=3224 Working Level Months) was not related to death from COPDs or any other NMRDs. CONCLUSIONS: The present findings do not indicate a relationship between mortality from COPD with silica dust or radon. However, validity of cause of death and lack of control for smoking remain potential sources of bias.

Toxicity of monazite particulates and its attenuation with a complex of bio-protectors.

BACKGROUND: Workers employed on mining, processing and storage of monazite are at risk of exposure to dust with expected adverse health effects. OBJECTIVES: To study the adverse health effects of monazite particles in experiments on rats and to test the possibility of attenuating these effects. METHODS: Outbred white rats were injected intratracheally with a suspension of ground monazite concentrate (MC) in order to investigate the cellular response of the lower airways 24 hours later and the organism's status 6 months after the injection. The bio-protective complex (BPC) tested in these experiments consisted of glutamate, an iodine preparation, methionine, a polyvitamin-polymineral composition, and/or "Eicosavitol" (fish oil preparation rich in PUFA, predominantly of the omega 3-group). Bio-protectors were administered together with the rat food and drink daily for one month before the MC injection in the short-term experiment, or over 6 months after such injection in the long-term experiment. RESULTS: MC induced manifestations of its cytotoxicity, fibrogenicity and systemic toxicity as well as genotoxicity. The tested BPC attenuated virtually all these effects. Although a similar protective potential of "Eicosavitol" against almost all of them was lower compared with that of BPC, combining BPC with "Eicosavitol" provided, as a rule, the greatest protective effect. CONCLUSION: It may be assumed that the many-sided adverse effects of MC on the organism is due, at least partially, to the presence in its composition of not only rare earth elements but also of natural radioisotopes of the thorium and uranium families. The combination of the bio-protectors tested was highly effective and may be recommended for administering in periodic preventive programmes to exposed workers.

[Clinical analysis on 75 cases of aluminosis caused by black fused alumina].

OBJECTIVE: To investigate the hazards of aluminum dusts to the exposed workers and the clinical features of aluminosis. METHOD: Retrospective investigation on 75 aluminosis patients from a certain factory diagnosed in Shanghai Occupational Diseases Hospital from 1972 to 2004 was carried out. RESULTS: There were 27 cases of aluminosis I (36.0%), 28 cases of aluminosis II (37.3%) and 20 cases of aluminosis III (26.7%) among 75 cases. The shortest exposure duration was 3 years, and the longest 17 years, and 37 cases of aluminosis occurred after exposure less than 10 years. hest radiographic examination mainly showed irregular micro-shadows: t (22/75), s (4/75), t/u (1/75), t/s (2/75), or predominantly irregular mixed microshadows s/p (5/75), s/r (1/75), t/p (9/75), t/q (5/75); some showed round shape micro-shadows: p (6/75), q (1/75), p/q (3/75), q/p (1/75). 27 cases showed large shadows, 20 cases of them were diagnosed as pneumoconiosis III. A lot of irregular micro-shadows gathered and developed to form uneven, loose and border-irregular masses. Most massive fibrosis looked like stripe or plait, located mostly in middle and upper lung field. 8 patients suffered from aluminosis with single side of massive fibrosis and 12 with both sides of massive fibrosis, accounting for 40% and 60% respectively. Mediastinal and bronchopulmonary lymph nodes were enlarged and calcified, accompanied with pleural thickening. CONCLUSIONS: Short exposure to high concentration of black fused alumina may cause serious aluminosis to the exposes. The hazards of aluminum dusts should not be ignored.

Evaluation of workers exposed to dust containing hard metals and aluminum oxide.

BACKGROUND: Fourteen worker exposed to hard metals and aluminum oxide were evaluated. METHODS: Six heavily exposed workers underwent bronchoscopy and bronchoalveolar lavage, and five workers underwent transbronchial biopsy. RESULTS: Microchemical analysis of transbronchial biopsies showed a high lung burden of exogenous particles, especially metal related to their hard metals exposure. Lung tissue and cellular changes, which were associated with exposure to hard metal and aluminum oxide, corresponded well with the microanalytic test results. CONCLUSIONS: Three workers had at biopsy diffuse interstitial inflammatory changes: two of them were asymptomatic with normal chest X-ray films, and one had clinically evident disease with severe giant cell inflammation. Two other workers showed focal inflammation. The worker showing clinical disease and one asymptomatic worker with interstitial inflammatory changes had evaluated bronchoalveolar lavage fluid-eosinophilia counts. These two were father (with clinical disease) and son (asymptomatic).

Lung health in sawmill workers exposed to pine and spruce.

Workers exposed to a variety of wood dusts have been shown to exhibit occupational asthma, lung function deficits, and elevated levels of respiratory symptoms. Despite the popularity of pine and spruce, the health effects of exposures to these woods have not been extensively investigated. A study was undertaken to investigate the respiratory health of a group of sawmill workers processing pine and spruce (n = 94). Data collection included a respiratory symptom questionnaire, spirometry, and allergy skin testing. The sawmill workers were compared with a group of oil field workers from the same geographic area who underwent the same study protocol (n = 165). The results showed that the sawmill workers had significantly lower average values for FEV1 and FEV1/FVC (%), adjusted for age, height, and smoking. The largest differences were for current smokers. Significantly elevated age and smoking-adjusted odds ratios (OR) were detected for shortness of breath (2.83; 95% confidence interval [CI], 1.47 to 5.46) and wheeze with chest tightness (2.58; 95% CI, 1.18 to 5.62). Nonsignificant elevations were also seen for usual cough (1.47; 95% CI, 0.68 to 3.16), usual phlegm (1.94; 95% CI, 0.98 to 3.87), shortness of breath with exercise (1.45; 95% CI, 0.66 to 3.20), chest tightness (1.43; 95% CI, 0.80 to 2.57), and attacks of wheeze (1.70; 95% CI, 0.79 to 3.68). Sawmill workers were 2.5 times as likely as oil field workers to report current asthma (95% CI, 0.76 to 8.32). Workers employed more than 3 years showed significantly more asthma (OR = 3.67; 95% CI, 1.00 to 13.5) and bronchitis (OR = 2.14; 95% CI, 1.02 to 4.52). Sawmill workers were only 43% as likely to report a history of hay fever (95% CI, 0.20 to 0.94). These health effects were noted despite an average concentration of respirable dust of 1.35 mg/m3 (range, 0.1 to 2.2 mg/m3). These levels are below the present occupational standard.

Inhaled particles and respiratory disease.

This brief discussion of inhaled particles, their manner of deposition and clearance, and their association with many human disease has been designed to remind us of the importance of particulate agents as sensitizers, via their allergen content, as causative agents of lung inflammation via their immunotoxic properties, as inducers of inflammatory alveolitis based on their content of antigens and adjuvant-like material, and as infectious agents. All these properties can play a part in a wide variety of allergic parenchymal, infectious, and industrial lung diseases and in building-related illnesses.

Pneumoconiose em trabalhadores de industria de abrasivos / Pneumoconiosis in workers of abrasive industry

O desenvolvimento de pneumopatia profissional em operarios de industrias de material abrasivo e incomun, sendo ate recentemente considerada a silica como causadora da pneumoconiose. Analisamos 22 operarios destas industrias em que se detectaram alteracoes radiograficas de torax. Todos eram do sexo masculino, com idades variando de 29 a 59 anos. Dezenove trabalhavam na producao de carbeto de silicio, tres na producao de oxido de aluminio e um em ambos, tendo ficado expostos por um periodo de 8 a 27 anos. As alteracoes radiologicas (ILO-80) predominantes foram pequenas opacidades em 20 pacientes. Associacao de grandes e pequenas opacidades foram observadas em um caso e grandes opacidades isoladamente em um. As pequenas opacidades foram predominantemente difusas e arredondadas. Nos dois doentes com grandes opacidades, estas se enquadravam como categoria B. Conclui-se que operarios em industrias de abrasivos encontram-se sob risco de desenvolvimento de pneumopatia profissional mais provavelmente desencadeada pela inalacao de carbeto de silicio.

[Pneumoconiosis in abrasive industry workers]. / Pneumoconiose em trabalhadores de indústria de abrasivos.

Occupational lung disease is uncommon in workers of abrasive industries. Twenty-two workers of these industries presenting radiological lung lesions were analysed. All were males with ages ranging from 29 to 59 years. Nineteen worked in the production of silicon carbide, three in the production of aluminum dioxide and one in both for a period of 8 to 27 years. In 20 patients the predominant radiological changes (ILO-80) were small opacities. Association of small and large opacities was observed in one case and isolated large opacities in another one. The small opacities were predominantly round and diffuse. The large opacities in both patients were classified as being of category B. It is concluded that the workers in abrasive industries are at a higher risk of developing occupational lung disease produced by silicon carbide.

[Effectiveness of climatic health resort complex treatment of patients with pneumoconiosis and dust-induced bronchitis using underwater massage shower]. / Effektivnost' klimaticheskogo sanatorno-kurortnogo lecheniia bol'nykh pnevmokoniozom i pylevym bronkhitom s vkliucheniem v lechebny kompleks protsedur podvodnogo dusha-massazha.

The article provides the results of studies of 167 cases affected with occupationally-related pneumoconiosis and dust bronchitis. 117 patients were treated with complex resort therapy including under-water massage, and 50 patients were given the same complex therapy without shower massage. The effectiveness of the therapeutic techniques were evaluated basing on both objective and subjective criteria, including supplementary laboratory and functional techniques. The results were positive in both groups, but in the major group, the favourable shifts were more expressed but statistically were not reliable. Thus, the underwater shower massage may be regarded as a positive but not decisive factor in the complex resort treatment of occupational diseases of lungs.

[Effects of mineral dust on generation of superoxide radicals and hydrogen peroxide by alveolar macrophages, granulocytes and monocytes]. / Vliianie mineral'nykh pylei na generatsiiu superoksidnykh radikalov i perekisi vodoroda al'veoliarnymi makrofagami, granulotsitami i monotsitami.

Phagocytosis of quartz dust by alveolar macrophages and monocytes of rabbits and human monocytes and granulocytes is accompanied by stimulation of substrateless recovery of nitroblue tetrazolium to formazan. It reflects activation of oxygen-dependent bactericidal phagocyte system and generation of active oxygen forms. Less fibrogenic and cytotoxic dust of aluminium oxide increased formazan formation insignificantly. Extracellular generation of superoxide radicals and hydrogen peroxide was not discovered during phagocytosis of quartz by alveolar macrophages and monocytes. Incubation of human granulocytes with silica caused, on contrary, considerable increase in exogenous generation of superoxide radicals and hydrogen peroxide. Less fibrogenic dust of aluminium oxide under the conditions had no effect on generation of hydrogen peroxide and induced acute decrease in generation of superoxide radicals by granulocytes. The obtained results testify both to the essential part of active oxygen form during pathologic processes with pneumoconiosis, and also to a great similarity among biochemical processes, characterizing interaction of alveolar macrophages and monocytes with mineral dust.

[A comparative evaluation of the effect of the dust factor on the respiratory organs of workers in contact with drug and plant dusts]. / Sravnitel'naia otsenka vliianiia pylevogo faktora na organy dykhaniia u rabotaiushchikh v kontakte s lekarstvennoi i rastitel'noi pyl'iu.

A comparative analysis of the data on the influence of complex medicinal and vegetable dusts (jute, flax, kenaf) on the respiratory organs, revealed the clinical signs of the byssinosis symptom-group in 49 cases (7.34%) of 667 technological textile workers investigated, and 10 cases (5.8%) of 171 tablet shop workers at a pharmaceutical plant. Byssinosis and its syndrome developed among the workers engaged in "dust shops" after 13 +/- 2.5 years of work. Similarity of the clinical symptoms was also proved by bronchospasm pharmacological diagnostic test (to a greater degree than in the sample group).

Acute symptoms in coffee workers.

Processing of green coffee before export, as carried out in Sri Lanka, is a very dusty process. Thirty-eight workers, who were exposed to coffee dust intermittently, were studied. They developed acute symptoms referrable to the eyes, nostrils and respiratory tract. Cough (84.2%), sputum (76.3%), sneezing (73.7%), difficulty in breathing (63.2%) and running nose (55.3%) were the commonest symptoms. Of the workers 10.5% had a wheeze. These symptoms lasted only during the hours that workers were exposed to the dust, and subsided on returning home after the day's work.

Study of chest radiographs and pulmonary ventilatory function in perlite workers.

A review of chest films from 152 workers who had been employed five or more years in perlite mining or processing showed none with small opacities of profusion 1/0 or higher. There were 14 films with doubtful changes (0/1), but these showed no correlation with type or duration of employment. Pulmonary function was measured in 122 current employees from the same plants. Multiple regression analysis showed no significant association between years of employment in perlite and either forced vital capacity (FVC) or forced expiratory volume (FEV1). There was a significant association between pack-years of cigarettes and both measurements. In 66 workers tested in 1975 and again in 1983, there was an average annual decrease in FVC of 32 mL, with 26 mL predicted by the Knudson formula, which is based on nonsmokers. The average annual decrease in FEV1 was 24 mL with 26 mL predicted. Comparison of groups with differing smoking patterns showed that the decreases in both FVC and FEV1 were associated with smoking. The 28 men who had added four or more pack-years in the interval between tests showed decreases in FVC and FEV1 of 44 mL/year and 31 mL/year, respectively, with 26 mL/year predicted for both groups. Those with less than four added pack-years (which included 26 nonsmokers) had decreases in FVC and FEV1 of 23 mL/year and 19 mL/year with 26 mL/year and 27 mL/year predicted.

[Pneumoconiosis in bauxite miners]. / Pneumoconiosi in minatori di bauxite.

The authors examined a group of 40 miners who were being working at an Apulian bauxite mine, presently inactive. Radiographic findings of pulmonary micronodulation without significant reduction of lung functions were showed in 15 miners. Mineralogical analysis of mine dust samples excluded any presence of more than 1% free silica. As a result of this study hypotheses have been formulated about pathogenesis of this moderated and non-invasive pneumoconiosis, showed in long exposed subjects to low silica content dusts.