Relations between occupational exposure to coal mine dusts,erythrocyte catalase and Cu++/Zn++ superoxide dismutase activities,and the severity of coal workers' pneumoconiosis

OBJECTIVES: To better understand the relations between occupational exposure, blood antioxidant enzyme activities, total plasma antioxidant concentration, and the severity of coal workers'' pneumoconiosis (CWP). METHODS: Blood samples were obtained from miners without CWP exposed to low dust concentrations for > or = 4 years at the time of the study (n = 105), or exposed to high dust concentrations for > or = 14 years at the time of the study (n = 58), and from retired miners with CWP (n = 19). Miners without CWP were classified into three subgroups according to their estimated cumulative exposure to dust. Chest x ray films were obtained for each miner. Miners were classified in five subgroups according to their International Labour Organisation (ILO) profusion grades. Univariate tests were completed by multiple linear regression analyses. RESULTS: The estimated cumulative exposure to dust was strongly positively related to erythrocyte catalase activity and strongly negatively related to Cu++/Zn++ SOD activity only in miners exposed to high dust concentrations for > or = 14 years at the time of the study (F tests p = 0.006 and p = 0.004 respectively). Moreover, catalase activity was strongly related to the severity of CWP expressed as five subgroups of ILO profusion grades (F test p = 0.003); the greatest difference in the mean values was found between the group of 1/1 to 1/2 ILO profusion grades and the group of 2/1 to 3/3 ILO profusion grades. CONCLUSION: These results are in good agreement with the hypothesis that production of reactive oxygen species may be an important event in the exposure to coal mine dusts and the severity of CWP. Erythrocyte catalase and Cu++/Zn++ SOD activities are more closely related to recent exposure to high dust concentrations than to cumulative exposure, and could be considered as biological markers of exposure rather than as markers of early adverse biological effect.       

Erythrocyte antioxidant enzyme activities in coal miners from three French regions

This study investigated whether differences in the prevalence and severity of coal workers' pneumoconiosis (CWP) between three coal mines could be related to differences in oxidative stress exposure as evaluated in vivo through red-blood-cell antioxidant enzyme activities. Blood samples were obtained from 229 miners selected according to their occupation and their pneumoconiotic status. The following biomarkers were evaluated: erythrocyte catalase, Cu²⁺/Zn²⁺ superoxide dismutase (Cu²⁺/Zn²⁺ SOD), and glutathione peroxidase activities. Antioxidant enzyme activities did not differ significantly between the group of surface workers in Lorraine and the group of underground miners without CWP in Lorraine and in the other coal mines. Erythrocyte Cu²⁺/Zn²⁺ SOD activity was slightly decreased in the group of active underground miners with simple pneumoconiosis as compared with the group of miners without CWP in Nord/Pas-de-Calais. No effect was seen between retired miners at different stages of CWP. Our findings indicate that differences in the prevalence and severity of CWP do not seem to be related to various oxidative activities of coal dust particles, at least as reflected by measurements of antioxidant enzyme activities in circulating erythrocytes in this study. Received: 3 March 1997 / Accepted: 14 October 1997     

Cross sectional and longitudinal study on selenium, glutathione peroxidase, smoking, and occupational exposure in coal miners

OBJECTIVES—To understand the variations of selenium (Se) concentration relative to changes in occupational exposure to coal dust, taking into account age and changes in smoking habits in miners surveyed twice, in 1990 and 1994. To better understand the relation of Se concentration with glutathione peroxidase activities (GSH-Px) in these miners.
METHODS—In 1994, blood samples were obtained from active (n=131) and retired (n=40) miners without coal worker''s pneumoconiosis, in whom Se concentration was available at both surveys and in whom International Labour Organisation (ILO) profusion grade had not been changed. Active miners were exposed to high dust concentrations (n=48) or low dust concentrations (n=83). Miners were classified into three subgroups according to their estimated cumulative exposure to dust, and into three subgroups according to their smoking habits.
RESULTS—Selenium concentration and GSH-Px activities were significantly lower in active than in retired miners (Se adjusted means: 62.6 v 72.2 ng/ml p=0.01). Moreover, Se concentration was lower in miners exposed to high compared with those exposed to low dust concentrations (adjusted means: 59.4 v 65.8). In miners exposed to high dust concentrations, Se concentration was significantly lower whereas erythrocyte GSH-Px activity was significantly higher in the subgroup with estimated cumulative exposure >68 mg/m³.y. In all miners, plasma GSH-Px activity was correlated with Se concentration (r=0.22, p<0.005). The 4 year Se changes were negatively related to exposure to high dust concentrations and positively related to change in exposure from high to retirement and to change from smoker to ex-smoker (p=0.01).
CONCLUSION—The variations of Se concentration in relation to changes in occupational exposure to coal dust and in smoking habits, and the close correlation found between plasma Se concentration and GSH-Px activity suggest that both are required in antioxidant defence. These results agree well with the hypothesis that the decrease in Se concentration reflects its use against reactive oxygen species generated by exposure to coal mine dust and by smoking.


     

Pneumoconiosis and advanced occupational lung disease among surface coal miners--16 states, 2010-2011

Coal workers' pneumoconiosis (CWP) is a chronic occupational lung disease caused by long-term inhalation of dust, which triggers inflammation of the alveoli, eventually resulting in irreversible lung damage. CWP ranges in severity from simple to advanced; the most severe form is progressive massive fibrosis (PMF). Advanced CWP is debilitating and often fatal. To prevent CWP, the Coal Mine Health and Safety Act of 1969 established the current federal exposure limit for respirable dust in underground and surface coal mines. The Act also established a surveillance system for assessing prevalence of pneumoconiosis among underground coal miners, but this surveillance does not extend to surface coal miners. With enforcement of the exposure limit, the prevalence of CWP among underground coal miners declined from 11.2% during 1970-1974 to 2.0% during 1995-1999, before increasing unexpectedly in the last decade, particularly in Central Appalachia. Exposure to respirable dust is thought to be less in surface than underground coal miners. Although they comprise 48% of the coal mining workforce, surface coal miners have not been studied since 2002. To assess the prevalence, severity, and geographic distribution of pneumoconiosis among current surface coal miners, CDC obtained chest radiographs of 2,328 miners during 2010-2011 through the Coal Workers' Health Surveillance Program of the National Institute for Occupational Safety and Health (NIOSH). Forty-six (2.0%) of 2,257 miners with >1 year of surface mining experience had CWP, including 37 who had never worked underground. Twelve (0.5%) had PMF, including nine who had never worked underground. A high proportion of the radiographs suggested silicosis, a disease caused by inhalation of crystalline silica. Surface coal mine operators should monitor worker exposures closely to ensure that both respirable dust and silica are below recommended levels to prevent CWP. Clinicians should be aware of the risk for advanced pneumoconiosis among surface coal miners, in addition to underground coal miners, to facilitate prompt disease identification and intervention.     

Decreased glutathione content and glutathione S-transferase activity in red blood cells of coal miners with early stages of pneumoconiosis.

Blood samples of miners heavily exposed to coal dust were examined for changes in glutathione S-transferase (GST) activity. Decreased GST activity was found in red blood cells of subjects with early stages of coal workers' pneumoconiosis (International Labour Office classification 0/1-1/2) when compared with control miners. At further progression of coal workers' pneumoconiosis (> or = 2/1), the activity of GST was not different from controls. In the same group with moderate coal workers' pneumoconiosis a decrease in GSH in red blood cells occurred. Decreases in GST activity in early stages of coal workers' pneumoconiosis, as well as the decreases in glutathione peroxidase (GPx) activity and in GSH concentrations reported earlier, may originate from damage caused by reactive oxygen species. These changes might imply an impairment of the detoxification capacity for electrophilic and oxidative compounds during this stage of the disease.     

Antioxidant response at early stages and low grades of simple coal worker's pneumoconiosis diagnosed by high resolution computed tomography

In miners exposed to coal dusts, coal worker's pneumoconiosis (CWP) can occur. The purpose of the present study is to better understand the relations between coal dust exposure and activities of blood plasma antioxidant enzymes, namely, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and lipid peroxidation end product malondialdehyde (MDA) concentration in coal workers with early and low grade simple CWP diagnosed by high resolution computed tomography (HRCT). Forty-three coal workers who had profusions of 0/1-2/2 according to ILO 1980 chest X-ray (CXR) classification, 43 coal workers without CWP (control group 1) and 44 healthy subjects (control group 2) who were randomly selected from the population register or recruited from the hospital staff were enrolled. Coal workers were reevaluated by HRCT (Hosoda-Shida classification) due to its higher sensitivity than standard CXR. Then, blood plasma SOD and GSH-Px activities and MDA plasma levels were measured. CWP was found positive in 46 of 89 coal workers by HRCT evaluation. Profusion 0 (P0, CWP not present), profusion 1 (P1, early CWP) and profusion 2 (P2, low grade CWP) were found in 43, 23 and 19 of patients found to have CWP by HRCT, respectively. We had no worker with profusion 3 (P3). Complicated CWP was shown in four of 46 patients and thesecases were excluded as the study was restricted to early and low-grade pneumoconiosis. In respect to the plasma levels of MDA and plasma activities of SOD and GSH-Px, statistically significant differences were found between CWP cases and control groups (p < 0.01, p < 0.01, p < 0.001 respectively). Statistical differences were also obtained for the plasma activities of SOD and GSH-Px and levels of MDA in relation to HRCT profusions (p < 0.05). In conclusion, these findings suggest an oxidative stress due to increased free radicals and reactive oxygen metabolite production in early stages and low grades of simple CWP diagnosed by HRCT.     

2003至2008年某矿务集团煤工尘肺发病情况分析

目的 分析某煤矿2003至2008年尘肺病检出情况,探讨该矿尘肺发病特点,为尘肺病的防治提供科学依据.方法 收集1949年以来井下粉尘监测数据及2003至2008年的健康监护资料和尘肺诊断资料,分析尘肺发病情况,根据不同年代的粉尘接触水平结合工种和工龄推算安全总粉尘累积剂量.结果 2003至2008年该矿务集团在岗工人职业性健康监护率呈逐年提高趋势,共新检出煤工尘肺病例296例,总检出率为0.57%,平均年检出率为0.32%;Ⅰ期煤工尘肺268例,占全部病例的90.59%,87.20%(258例)的煤工尘肺患者为采掘工;新发病例的接尘工龄最短为3年,最长38年;每年总粉尘累积剂量为86.1～4926.0mg/m3.用百分位数法(第99%百分位数)推算煤矿井下工人每年安全总粉尘累积剂量为120.6 mg/m3.结论 尘肺病防治的重点工种是采掘工,在现有工作条件下井下采掘作业工龄不应超过13年.

Abstract：

Objective Analyzed associations among the incidence of coal workers' pneumoconiosis from 2003 to 2008, jobs, exposure years and cumulative total dust exposure levels(CTE ) and found the current characteristics of the mine incidence of pneumoconiosis disease. Methods collected the health care information of the new diagnosed pneumoconiosis of underground mine workers from 2003 to 2008 and the dust monitoring data of underground mine from 1949 and estimated the personnel cumulative total dust exposure levels (CTE); analyzed the incidence features of the new diagnosed pneumoconiosis. Results The rates of health surveillance of workers were gradually improved from 2003 to 2008 and 296 new coal workers pneumoconiosis were diagnosed. The total incidence was 0.57%, and the average annual rate was 0.32%. Among the new diagnosed cases, phase I accounted for 90.5% and the 87.2% from coal mine drillers. The shortest exposure period was 3 years and the longest was 38 years, and the cumulative total dose of dust was varied between 86. 1 and 4926 mg/m3 per year. The total dust accumulated limited dose was calculated by the percentile method to prevent 99% of miners from pneumoconiosis, which was 120.6 mg/m3 per year, so we suggested that the exposure years should be shorter than 13 years under the current working conditions. Conclusions Preventive coal workers' pneumoconiosis should be focused on mine drillers and their limited exposure years should be within 13 years.     

提高接触粉尘工人抗超氧阴离子(O-*2)功能的研究——人体对生产性粉尘免疫反应系列研究之二

目的　探讨提高接触粉尘工人体内抗超氧阴离子 (O-·2 )能力的方法 ,为寻找尘肺早期诊断的辅助指标及开壁治疗新途径提供依据。方法　检测接尘作业工人血液中超氧化物歧化酶 (SOD)及微量元素 (Cu、Zn、Mn)的含量 ,并对SOD含量下降工人进行治疗观察。结果　检测结果表明 ,接触碳素粉尘及碳黑粉尘工人血液中微量元素铜锌含量有不同程度下降 ,其中锌含量下降较明显 ;接尘工人血液中SOD含量下降 ,其下降幅度与接尘工龄相关不明显 ;接尘工人血液中SOD含量下降者经治疗后有明显提高 (2 4 2 %～ 5 3 3 % )。结论　接尘工人经用微量元素及清除自由基的药物治疗后 ,SOD含量有明显提高 ,为此 ,建议定期给接尘工人补充微量元素 (Cu、Zn)及维生素C、E ,提高他们抗超氧阴离子功能     

煤矿呼吸性粉尘与尘肺的剂量-反应关系

本文采用呼吸性粉尘与总粉尘同步对照监测方法,计算出两种粉尘浓度比值:岩尘为1:4.6;煤尘为1:22.3。把历年总粉尘浓度值转换为呼吸性粉尘浓度值,用寿命表法分析呼吸性粉尘接尘量与尘肺发病的剂量-反应关系。剂量-反应关系回归方程;掘进工为Y=3.3757LgX-2.6666(r=0.9585);采煤工为Y=7.2383 LgX-8.7793(r=0.9751)。由此推算出:呼吸性岩尘(含游离SiO_238.2%)容许浓度为1.18mg/m~3;呼吸性煤尘(含游离SiO_2<5%)容许浓度为1.27mg/m~3。作者力图能为国家有关部门制定呼吸性粉尘浓度卫生标准提供参考依据。     

Exposure-response analysis of mortality among coal miners in the United States

The quantitative relationship between exposure to respirable coal mine dust and mortality from nonmalignant respiratory diseases was investigated in a study of 8,878 working male coal miners who were medically examined from 1969 to 1971 and followed to 1979. Exposure-related mortality was evaluated using Cox proportional hazards modeling for underlying or contributing causes of death and modified lifetable methods for underlying causes. For pneumoconiosis mortality, the lifetable analyses showed increasing standardized mortality ratios (SMRs) with increasing cumulative exposure category. Significant exposure-response relationships for mortality from pneumoconiosis (P < 0.001) and from chronic bronchitis or emphysema (P < 0.05) were observed in the proportional hazards models after controlling for age and smoking. No exposure-related increases in lung cancer or stomach cancer were observed. Pneumo coniosis mortality was found to vary significantly by the rank of coal dust to which miners were exposed. Miners exposed at or below the current U.S. coal dust standard of 2 mg/m³ over a working lifetime, based on these analyses, have an elevated risk of dying from pneumoconiosis or from chronic bronchitis or emphysema.     

Oxidative DNA damage in peripheral blood lymphocytes of coal workers

Reactive oxygen species are important mediators of both mineral dust-induced (malignant) lung disease and in vitro DNA damage. Therefore, we studied in vivo oxidative DNA damage in coal workers who had been chronically exposed to silica-containing dust. In peripheral blood lymphocytes of 38 retired coal miners (eight with coal workers pneumoconiosis, 30 references) and 24 age-matched, non-dust-exposed controls 7-hydro-8-oxo-2-deoxyguanosine (8-oxodG) was determined by reversed phase high-performance liquid chromatography with electrochemical detection. The ratio of 8-oxodG residues to deoxyguanosine (dG) was related to individual cumulative dust exposure estimates and pneumoconiotic stage as established by chest radiography. The ratio of 8-oxodG to dG(x 10^–5) in lymphocytes did not differ between miners with coal workers' pneumoconiosis (2.61 ± 0.44) and miners without coal workers' pneumoconiosis (2.96 ± 1.86). However, oxidative DNA damage in all miners was higher than in the non-dust-exposed controls (1.67 ± 1.31). 8-oxodG/dG ratio was not related to individual cumulative coal dust exposure, age or smoking (pack years) when evaluated by multiple linear regression. We suggest that oxidative damage to the DNA of peripheral blood lymphocytes may be introduced by increased oxidative stress responses in subjects chronically exposed to mineral dusts. Whether this is an important pathway in the suggested carcinogenicity of silica is still an open question.     

Effects of occupational exposure to diesel exhaust on porphyrin metabolism in lymphocytes of workers employed at black coal and oil-shale mines

BACKGROUND: This pilot study was conducted to investigate biochemical effects of exposure to diesel engine exhaust at two mines. For this purpose, heme biosynthesis, and PP association with DNA (PP/DNA) in lymphocytes of miners exposed to diesel exhaust were determined. METHODS: The pilot study was carried out at a black coal mine in Czech Republic, and at an oil-shale mine in Estonia. The subjects were ten drivers from each mine, who were exposed to diesel exhaust (underground workers). Control groups consisted of ten maintenance workers from each mine (surface workers). The content of 1-nitropyrene (NP) in respirable dust was measured using GC-MS. The levels of PP, PP/DNA, heme, and activity of ferrochelatase (FC) were determined by spectrophotometry. RESULTS: The exposure to diesel exhaust evaluated as the level of NP associated to particulate matter in air. NP level was significantly higher in oil-shale mine compared with coal mine. The values of PP and PP/DNA in lymphocytes appeared to be significantly increased only in miners in the oil-shale mine. There was no difference in the levels of PP and PP/DNA and FC activity between surface workers and miners at the coal mine. The level of heme in lymphocytes of coal mine miners was significantly higher than in miners of the oil-shale mine. The activity of FC was significantly lower in underground workers compared to surface workers at this mine. High level of NP was accompanied by an increase of alterations in cells porphyrin metabolism in lymphocytes of miners. CONCLUSIONS: Alterations of porphyrin and heme metabolism in peripheral lymphocytes may serve as biomarker in assessment of exposure to diesel exhaust effects.     

British data on coal miners'' pneumoconiosis and relevance to US conditions.

OBJECTIVES. The current primary federal dust standard for US underground coal miners of 2 mg/m3 respirable dust is based on British epidemiological information on exposure-response derived in 1969. Since then, much new information has become available. This paper reviews and compares the available information as it relates to the US mining situation. METHODS. Recent exposure-response information on pneumoconiosis and dust exposure derived by British researchers was employed to estimate working-life risks of pneumoconiosis for miners exposed to 2 mg/m3. RESULTS. It is estimated that close to 9% of underground coal miners who work for 40 years in a 2 mg/m3 environment would develop pneumoconiosis (category 1 or greater). Progressive massive fibrosis would develop in 0.7%. CONCLUSIONS. There are unresolved questions relating to the validity of extrapolating findings on British mines and miners to the US and also in predicting disease levels at the low end of the dust exposure spectrum. Given the data available, current information suggests miners who are employed for a working life-time at the current federal dust limit of 2 mg/m3 are still at risk of developing pneumoconiosis.     

Epidemiological evaluation of release of monocyte TNF-alpha as an exposure and effect marker in pneumoconiosis: a five year follow up study of coal workers.

OBJECTIVES--To determine (a) reproducibility with previous cross sectional findings, and (b) the predictive value of initial release of tumour necrosis factor-alpha (TNF-alpha) towards later progression of coalworkers' pneumoconiosis (CWP). METHODS--Release of monocyte TNF-alpha after in vitro stimulation with coal mine dust, silica, and endotoxin was measured in 104 retired miners and was related to stage of CWP (chest radiograph) and cumulative exposure. A subgroup of 46 miners was screened by high resolution computed tomography (HRCT). Prospective analysis of TNF-alpha (40 out of 104 miners involved in the previous TNF-alpha study) was done by relating initial TNF-alpha to five year progression of CWP measured by comparison of paired chest radiographs. RESULTS--As observed previously, dust stimulated release of TNF-alpha was increased in miners, especially in the early stages of pneumoconiosis. Cumulative exposure was related to pneumoconiotic stage but not to release of TNF-alpha. This excluded TNF-alpha as an exposure marker. Initial concentrations (1987) of TNF-alpha were related to later progression of CWP. Miners who showed abnormally high dust stimulated release of TNF-alpha had an increased risk of progression in CWP (relative risk 8.1). CONCLUSIONS--These results show (a) the significant involvement of TNF-alpha in pneumoconiosis in humans induced by coal dust and (b) that this routine test possibly constitutes a powerful tool to estimate individual prognosis of pneumoconiotic disease, even after the end of occupational exposure.     

不同煤种呼吸性粉尘与尘肺病患病风险的剂量-反应关系分析

目的 探讨无烟煤、烟煤、褐煤呼吸性粉尘与尘肺病累计患病率的剂量-反应关系,为科学制定职业卫生标准提供依据。方法 对9处国有煤矿采煤工人的接尘和尘肺病患病情况进行调查研究,以寿命表法分别计算出无烟煤、烟煤、褐煤呼尘累计接尘量对应的累计患病率,利用线性回归方程进行单侧区间统计控制,得到呼尘接触浓度限值。结果 9处煤矿共21 000名采煤工人纳入研究,其中无烟煤、烟煤、褐煤煤矿采煤工人尘肺病检出率分别为11.27%、21.32%、6.00%,平均接尘工龄为20.12、22.88、25.21年。无烟煤、烟煤、褐煤煤矿采煤工人呼尘累计接尘量与尘肺病累计患病率的剂量-反应关系分别为线性回归方程y=5.788x-16.043（R²=0.949）、y=5.679x-16.837（R²=0.904）、y=6.465x-19.573（R²=0.944）。当接尘30年尘肺累计患病率≤1%时,以安全系数为1.2计算,三者呼尘接触浓度限值分别为1.7、2.3、3.9 mg/m³。结论 不同煤种的尘肺病检出率、平均接尘工龄、呼尘接触浓度限值均不同,在煤尘累计接尘量相似情况下,煤的挥发分越低（含碳量越高）,累计患病率越高（无烟煤 > 烟煤 > 褐煤）。建议按照不同煤种分别制定国家职业卫生煤尘标准。     

Quantitative relations between exposure to respirable coalmine dust and coalworkers'' simple pneumoconiosis in men who have worked as miners but have left the coal industry.

Present estimates of the quantitative relations between exposure to mixed respirable coalmine dust and risk of developing coalworkes' simple pneumoconiosis are based on studies of working miners. These studies did not include men who had been miners but had left the coal industry, and it was not known whether the estimates of risk were also appropriate for these men. The results are reported of a study in which the dust/disease relations in men who have been miners but have left the industry have been compared with those in men who have remained in it. A sample of 17738 men who were first examined when working in 24 British collieries in the 1950s has been followed up about 22 years later. It was possible to examine 61% of the survivors, 44% of the original sample. Simple pneumoconiosis was more frequent among men (particularly older men) who had left the industry than among those who had stayed in it. A detailed analysis did not show any systematic or statistically significant difference between men who stayed and men who left in the quantitative relations between dust exposure and simple pneumoconiosis. Present estimates of risk of simple pneumoconiosis in relation to exposure to mixed respirable dust in working miners adequately describe the relation found in men who have been miners but have left the industry.     

Quantitative relations between exposure to respirable coalmine dust and coalworkers' simple pneumoconiosis in men who have worked as miners but have left the coal industry

Present estimates of the quantitative relations between exposure to mixed respirable coalmine dust and risk of developing coalworkes' simple pneumoconiosis are based on studies of working miners. These studies did not include men who had been miners but had left the coal industry, and it was not known whether the estimates of risk were also appropriate for these men. The results are reported of a study in which the dust/disease relations in men who have been miners but have left the industry have been compared with those in men who have remained in it. A sample of 17738 men who were first examined when working in 24 British collieries in the 1950s has been followed up about 22 years later. It was possible to examine 61% of the survivors, 44% of the original sample. Simple pneumoconiosis was more frequent among men (particularly older men) who had left the industry than among those who had stayed in it. A detailed analysis did not show any systematic or statistically significant difference between men who stayed and men who left in the quantitative relations between dust exposure and simple pneumoconiosis. Present estimates of risk of simple pneumoconiosis in relation to exposure to mixed respirable dust in working miners adequately describe the relation found in men who have been miners but have left the industry.     

Assessment of respirable dust and its free silica contents in different Indian coalmines

Assessment of respirable dust, personal exposures of miners and free silica contents in dust were undertaken to find out the associated risk of coal workers' pneumoconiosis in 9 coal mines of Eastern India during 1988-91. Mine Research Establishment (MRE), 113A Gravimetric Dust Sampler (GDS) and personal samplers (AFC 123), Cassella, London, approved by Director General of Mines Safety (DGMS) were used respectively for monitoring of mine air dust and personal exposures of miners. Fourier Transform Infra-red (FTIR) Spectroscopy determined free silica in respirable dusts. Thermal Conditions like Wet Bulb Globe Temperature (WBGT) index, humidity and wind velocity were also recorded during monitoring. The dust levels in the face return air of both, Board & Pillar (B&P) and Long Wall (LW) mining were found above the permissible level recommended by DGMS, Govt. of India. The drilling, blasting and loading are the major dusty operations in B&P method. Exposures of driller and loader were varied between, 0.81-9.48 mg/m3 and 0.05-9.84 mg/m3 respectively in B&P mining, whereas exposures of DOSCO loader, Shearer operator and Power Support Face Worker were varied between 2.65-9.11 mg/m3, 0.22-10.00 mg/m3 and 0.12-9.32 mg/m3 respectively in LW mining. In open cast mining, compressor and driller operators are the major exposed groups. The percentage silica in respirable dusts found below 5% in all most all the workers except among query loaders and drillers of open cast mines.     

Dust exposure during small-scale mining in Tanzania: a pilot study

Small-scale mining in developing countries is generally labour-intensive and carried out with low levels of mechanization. In the Mererani area in the northern part of Tanzania, there are about 15000 underground miners who are constantly subjected to a poor working environment. Gemstones are found at depths down to 500 m. The objectives of this pilot study were to monitor the exposure to dust during work processes, which are typical of small-scale mining in developing countries, and to make a rough estimation of whether there is a risk of chronic pulmonary diseases for the workers. Personal sampling of respirable dust (n = 15) and 'total' dust (n = 5) was carried out during three consecutive days in one mine, which had a total of 50 workers in two shifts. Sampling started immediately before the miners entered the shaft, and lasted until they reappeared at the mine entrance after 5-8 h. The median crystalline silica content and the combustible content of the respirable dust samples were 14.2 and 5.5%, respectively. When drilling, blasting and shovelling were carried out, the exposure measurements showed high median levels of respirable dust (15.5 mg/m(3)), respirable crystalline silica (2.4 mg/m(3)), respirable combustible dust (1.5 mg/m(3)) and 'total' dust (28.4 mg/m(3)). When only shovelling and loading of sacks took place, the median exposures to respirable dust and respirable crystalline silica were 4.3 and 1.1 mg/m(3). This study shows that the exposure to respirable crystalline silica was high during underground small-scale mining. In the absence of personal protective equipment, the miners in the Mererani area are presumably at a high risk of developing chronic silicosis.     

煤矽肺患者血中微量元素和脂质过氧化的改变

目的 了解煤矽肺患质过氧化水平。方法 检测煤矽肺患血清中微量元素Cu、Zn含量及MDA、SOD和GSH的水平。结果 煤矽肺患血清中Cu、Zn、MDA、SOD明显高于对照组,GSH明显低于对照组。煤矽肺患工龄、期别不同,其脂质过氧化水平也不同。吸烟可促进脂质过氧化发生改变。结论 煤尘可引起接触人群脂质过氧化紊乱。脂质过氧化可能是影响煤矽肺发生、发展的主要因素之一。