Validation of autopsy data for epidemiologic studies of coal miners

BACKGROUND: South Africa has one of the largest miner autopsy databases, PATHAUT, dating back to 1925. The diagnoses recorded on this database have never been evaluated for coal miners. The objective was to determine the validity of the autopsy diagnoses for coal workers, specifically bronchitis, silicosis, tuberculosis, coal workers' pneumoconiosis and emphysema, from 1975 to 1997. METHODS: Three pathologists experienced in miner respiratory pathology conducted the review. They were blinded to employment and medical histories as well as to previous pathological diagnoses on PATHAUT and reviewed 28 coal miners with mixed mining exposures, and 31 cases with exclusive coal mine exposure--all selected randomly. The reviewers' independent and consensus diagnoses were compared to PATHAUT. An additional 31 cases with available whole mount sections were reviewed for the diagnosis of emphysema. Kappa statistics were used to determine degrees of agreement among reviewers and between reviewers and PATHAUT. RESULTS: There was good to excellent agreement between the reviewers and PATHAUT for silicosis, tuberculosis, and pneumoconiosis that had progressed beyond the stage of macules, among the mixed and exclusive coal exposure cases. There was good to excellent inter-reviewer agreement for all diseases except bronchitis (agreement=fair to very good). For emphysema, there was good to very good inter-reviewer agreement but fair agreement with PATHAUT. CONCLUSIONS: This, the first systematic review of PATHAUT autopsy diagnoses made on coal workers, showed that PATHAUT can be used with confidence to establish a diagnosis of moderate to severe grades of coal workers' pneumoconiosis. The grade of emphysema recorded on PATHAUT could be used for epidemiological purposes, when whole mount sections have been prepared.     

煤工尘肺患者血清中基质金属蛋白酶-9及其抑制因子水平的变化

目的 探讨煤工尘肺患者血清中基质金属蛋白酶(MMP-9)及基质金属蛋白酶抑制剂(TIMP-9)水平的变化及意义.方法 采用双抗体夹心ELISA法检测188例煤工尘肺(煤肺组53例,煤矽肺组67例,矽肺组68例)、57例0期(0~+期组)、64例接尘对照组和50例健康对照组血清中MMP-9及TIMP-9含量;分析血清中MMP-9和TIMP-9水平在各煤工尘肺组及各对照组间的变化,以及二者的相关性;并根据煤工尘肺期别、是否有并发症以及接尘年限等因素进行分析.结果 煤肺组血清中MMP-9水平为17.16 ng/ml、煤矽肺组为15.14ng/ml,矽肺组为17.50 ng/ml,与健康对照组比较,差异均有统计学意义(P<0.05)与接尘对照组、0~+组比较,均呈降低趋势,其中矽肺组及煤矽肺组差异有统计学意义(P<0.05).3组煤工尘肺患者血清中MMP-9水平比较,差异无统计学意义(P>0.05);煤肺组、煤矽肺组和矽肺组血清中TIMP-9水平分别为(330.00±108.42),(312.044±120.09),(366.81±135.50)ng/ml,均低于健康对照组,其中矽肺组和煤肺组血清中TIMP-9水平较接尘对照组、1~+组明显增高,差异有统计学意义(P<0.05),3组煤工尘肺组间比较,矽肺组血清中TIMP-9水平较煤矽肺组升高,差异有统计学意义(P<0.05).3组煤工尘肺患者血清中MMP-9和TIMP-9水平按不同的疾病分期、是否有并发症以及接尘年限进行分析,差异均无统计学意义(P>0.05);矽肺组血清中TIMP-9水平与年龄呈正相关(r=0.249,P<0.05),血清中MMP-9和TIMP-9水平在接尘对照组中呈正相关(r=0.294,P<0.05),其他组中未发现相关性.结论 血清中MMP-9与TIMP-9水平变化与粉尘对机体的损害程度有关,MMP-9与TIMP-9共同参与了煤工尘肺的病理生理过程;动态观察0~+期及健康煤矿工人血清中MMP-9和TIMP-9水平,可为煤工尘肺的预防及早期诊断提供参考.     

Emphysema and airway obstruction in non-smoking South African gold miners with long exposure to silica dust.

OBJECTIVE--Occupational exposure to silica dust is associated with significant impairment of lung function. The present study investigates which pathological changes in the lung are associated with impairment of lung function in silica dust exposed workers who were life-long non-smokers. METHODS--242 South African white gold miners who were lifelong non-smokers and who had a necropsy at death were studied. The pathological features identified at necropsy were the degree and type of emphysema, the presence of airway disease, and the degree of silicosis in the lung parenchyma and pleura. These features were related to lung function tests done a few years before death, to type of impairment (obstructive or restrictive), and to cumulative silica dust exposure. RESULTS--The degree of emphysema found at necropsy was not associated with a statistically significant impairment of lung function or with dust exposure. The degree of silicosis in the lung parenchyma and the large airways disease (based on mucus gland hyperplasia) were associated with a statistically significant impairment of lung function. The large airway disease was, however, not positively associated with dust exposure or silicosis. In miners with a moderate or a higher degree of limitation of airflow the main findings were silicosis, heart disease, and obesity. The presence of small airways disease could not be established from the necropsy material. CONCLUSION--The results indicate that the level of exposure to silica dust to which these miners were exposed, without a confounding effect of tobacco smoking, is not associated with a degree of emphysema that would cause a statistically significant impairment of lung function. Silicosis of the lung parenchyma was associated with loss of lung function. Other factors that may play a part in impairment of lung function in these miners are obesity and heart disease.     

An investigation into the relationship between coal workers' pneumoconiosis and dust exposure in U.S. coal miners.

The National Study of Coal Workers' Pneumoconiosis (NSCWP) is a large, continuing epidemiologic study of the respiratory health of U.S. coal miners. By using information from the study, prevalence of coal workers' pneumoconiosis (CWP) was related to indexes of dust exposure obtained from research and compliance sampling data. Clear relationships between prevalences of both simple CWP and progressive massive fibrosis (PMF) and estimated dust exposure were seen. Additional effects independently associated with coal rank (% carbon) and age were also seen. Logistic model fitting indicated that between 2% and 12% of miners exposed to a 2-mg/m3 dust environment in bituminous coal mines would be expected to have Category 2 or greater CWP after a 40-yr working life; PMF would be expected for between 1.3% and 6.7%. The risks for anthracite miners appeared to be greater. There was a suggestion of a background level of abnormality, not associated with dust exposure, but increasing with age. Although there are certain weaknesses in the data used to derive these exposure estimates, the results are in general agreement with, but somewhat greater than, some recent findings for British coal miners.     

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.     

Genetic polymorphisms of MnSOD, GSTM1, GSTT1, and OGG1 in coal workers' pneumoconiosis

Little is known about the genetic susceptibility to coal workers' pneumoconiosis (CWP). We investigated the association between genetic polymorphisms of MnSOD, GSTM1, GSTT1, or OGG1 and susceptibility to CWP. The study population was composed of 259 Chinese retired coal miners who had similar dust exposure histories. Of these, there were 99 cases with International Labor Organization chest radiologic criteria for CWP and 160 controls (with no radiologic criteria for CWP). Individual dust exposure variables were estimated from work histories, and smoking information was obtained from interviews. Polymerase chain reaction-based techniques evaluated the genotypes of all study subjects. There were no differences in genotype frequency of MnSOD, GSTM1, GSTT1, and OGG1 between miners with CWP and miners without CWP, by logistic regression analysis. Cumulative dust exposures, but not genetic polymorphisms, were associated significantly with the presence of CWP. This study illustrates the complexity of factors that may contribute to the development of CWP.     

煤矿工人肺功能损害的调查研究

本文用协方差、Ｍａｎｔｅ－Ｈａｅｎｓｚｅｌ和Ｌｏｇｉｓｔｉｃ方法对煤矿工人肺功能进行统计分析，结果表明：反映煤矿工人肺功能损害的敏感而稳定的指标有ＦＥＶ１、ＦＥＶ１％，ＭＴＴ和ＲＶ％，煤矿工人肺功能损害以阻塞型为主，功能残气增加为其明显特点，混合型次之，限制型最少，肺功能损害概率随单纯性煤工尘肺期别的增加而增大，影响煤矿工人肺功能损害的主要因素是年龄、接尘工龄、吸烟指数和接尘工龄与吸烟年的交互作用     

Risk of pulmonary tuberculosis relative to silicosis and exposure to silica dust in South African gold miners [published erratum appears in Occup Environ Med 1999 Mar;56(3):215-6]

OBJECTIVES: To investigate the following questions. (1) Is silica dust on its own, without the presence of silicosis, associated with an increased risk of pulmonary tuberculosis (PTB) in workers exposed to silica dust? (2) In the absence of silicosis is the excess risk dose related? (3) What is the predominant chronological sequence between the development of PTB and the development of silicosis after the end of exposure to dust? METHODS: A cohort of 2255 white South African gold miners has been followed up from 1968 to 1971, when they were 45-55 years of age, to 31 December 1995 for the incidence of PTB. During the follow up 1592 (71%) men died. Of these, 1296 (81%) had a necropsy done at the National Centre for Occupational Health (NCOH) to determine the presence of silicosis and PTB. The incidence of PTB in the cohort was studied relative to cumulative exposure to dust and the onset of silicosis. For the miners with necropsy, the incidence for PTB was studied relative to the severity of silicosis found at necropsy. RESULTS: There were 115 subjects who developed PTB. The total person- years of follow up was 39,319. For the whole cohort, the factors associated with increased risk of PTB were cumulative exposure to dust (mg/m3.y) (the adjusted rate ratio (RR) 1.07; (95% confidence interval (95% CI) 1.04 to 1.10)), silicosis diagnosed radiologically (3.96 (2.59 to 6.06)), and tobacco pack-years (1.02 (1.01 to 1.03)). The RR (95% CI) for PTB increased with increasing quartiles of cumulative exposure to dust 1.0, 1.51 (0.78 to 2.91), 2.35 (1.28 to 4.32), and 3.22 (1.75 to 5.90). In miners who did not have radiologically diagnosed silicosis (n = 1934, PTB = 74), the adjusted RR (95% CI) for PTB and cumulative exposure to dust was 1.10 (1.06 to 1.13), and increased with quartiles of cumulative exposure to dust as 1.00, 1.46 (0.70 to 3.03), 2.67 (1.37 to 5.23), and 4.01 (2.04 to 7.88). For the subjects who had a necropsy (n = 1296, PTB = 70), the adjusted RR (95% CI) for PTB increased with the severity of silicosis found at necropsy; 1.0 for no silicosis, 1.88 (0.97 to 3.64) for negligible, 2.69 (1.35 to 5.37) for slight, and 2.30 (1.16 to 4.58) for moderate or marked silicosis. For subjects who had a necropsy and no silicosis (n = 577, PTB = 18), the adjusted RR (95% CI) increased slightly with quartiles of cumulative dust 1.0, 1.11 (0.31 to 4.00), 1.42 (0.43 to 4.72), and 1.38 (0.33 to 5.62). CONCLUSION: Exposure to silica dust is a risk factor for the development of PTB in the absence of silicosis, even after exposure to silica dust ends. The risk of PTB increases with the presence of silicosis, and in miners without radiological silicosis, with quartiles of exposure to dust. The severity of silicosis diagnosed at necropsy was associated with increasing risk of PTB and even < 5 nodules--that is, undetectable radiologically--was associated with an increased risk of PTB. The diagnosis of PTB was on average 7.6 years after the end of exposure to dust, at around 60 years of age. The onset of radiological silicosis preceded the diagnosis of PTB in 90.2% of the cases with PTB who had silicosis. The results have implications for medical surveillance of workers exposed to silica dust after the end of exposure.       

金属矿工与煤工尸检肺内粉尘及金属元素含量分析

目的 研究金属矿工与煤工尘肺尸检肺内偻尘、游主二氧化硅及元素的含量。方法 ３６例矿工尸检双肺样品,分别用Ｇｕｅｒｔ法、式外分光扫描法、原子吸收人姚光度法测定肺内粉尘、游离二氧化硅及金属元素含量。结果 随肺内滞留汾尘、游离二氧化硅含量的增加,尘病变加重;相同期别的金属矿工与采煤工尘肺,肺内粉法坦前者低于后者,游离二氧化硅量二者基本接近,肺组织中元素含量金属矿工高于采煤工,并与肺期别无关。结论 肺内粉     

煤尘职业接触者和早期煤工尘肺BAL液中表面活性物质研究

目的 探讨煤尘职业接触者和早期煤工尘肺患者BAL液中表面活性物质含量改变特点及其意义。方法 采煤工人23人,按X线诊断煤工尘肺期别分为0期（煤尘接触者）组7人、0^ 组8人和I期组8人,并取健康农民7人为对照组。经纤维支气管肺泡灌洗（BAL）收集BAL液,测定表面活性蛋白A(SP－A）和磷脂（PL）及其组分含量。结果 0期组BAL液中SP－A含量、SP－A／PL和PG／PI明显高于对照组（P＜0．01）,且随煤工尘肺期别增加而有降低趋势。结论 BAL液中SP－A含量、SP－A／PL和PG／PI升高可能是煤尘接触的早期效应指标。     

Respiratory Status of Surface Coal Miners in the United States

The United States Public Health Service examined 1,438 surface coal miners to determine the prevalence of coal worker’s pneumoconiosis (CWP), chronic bronchitis, and ventilatory impairment among them. Four percent (fifty-nine individuals) showed some roentgenographic evidence of pneumoconiosis, but only seven miners had films interpreted as CWP of category2 or greater (according to the UlCC/Cincinnati classification system). Moreover, most of the affected miners had worked in underground coal mines for prolonged periods. Significant decrements in pulmonary function to increasing exposure to surface mine dust were demonstrated only in the forced vital capacity of smokers. Increased prevalence of chronic bronchitis with increasing exposure was found in all smoking categories. However, significant airway obstruction was an uncommon finding (6.6%) in nonsmoking miners. Employment in surface mining was not likely to cause either the development of CWP or clinically significant respiratory impairment.     

Pathological findings in mine workers: II. Quality of the PATHAUT data

To assess the feasibility of using the pathology automation system (PATHAUT) for research, the quality of the data was explored by examining who comes to autopsy, the quality of the autopsy material, interobserver variability, and repeatability of diagnoses. The data indicated that autopsy rates in the gold mining industry, especially for whites, are high and that even among blacks, gold miners are represented in proportions exceeding the relative size of the working population. Because of the perception of the autopsy service as a means of obtaining compensation, miners with occupational diseases fully compensated in life are probably underrepresented. The autopsy material submitted for full autopsy is generally better preserved than cardiorespiratory organs that are sent for examination. The gold mining industry has a high proportion of full autopsies as does the Iron and Steel Corporation of South Africa. Full autopsies are more commonly performed on older deceased miners. This was true for both blacks and whites. The allocation of material to pathologists for full autopsies and examinations of the cardiorespiratory organs were clearly not random, and this may affect comparisons among pathologists. Active tuberculosis, silicosis, and emphysema prevalences appeared fairly comparable across pathologists; however, there was wide variability in the prevalence of bronchiolitis as determined by the pathologists. Agreement between the diagnoses on PATHAUT and reclassifications by single pathologists was very good for the severity of emphysema and the histological type of bronchogenic carcinoma.     

Silicosis and lung cancer in North Carolina dusty trades workers

Since 1940, 760 cases of silicosis have been diagnosed as part of the State of North Carolina's (NC) pneumoconiosis surveillance program for dusty trades workers. Vital status was ascertained through 1983 for 714 cases that had been diagnosed since 1940 and death certificates were obtained for 546 of the 550 deceased. Mortality from tuberculosis, cancer of the intestine and lung, pneumonia, bronchitis, emphysema, asthma, pneumoconiosis, and kidney disease was significantly increased in whites. Mortality from tuberculosis, ischemic heart disease, and pneumoconiosis was significantly increased in non-whites. The standardized mortality ratio (95% CI) for lung cancer based on U.S. rates was 2.6 (1.8-3.6) in whites, 2.3 (1.5-3.4) in those who had no exposure to other known occupational carcinogens, and 2.4 (1.5-3.6) in those who had no other exposure and who had been diagnosed for silicosis while employed in the NC dusty trades. Age-adjusted lung cancer rates in silicotics who had no exposure to other known occupational carcinogens were 1.5 (.8-2.9) times higher than that in a referent group of coal miners with coalworkers' pneumoconiosis (CWP) and 2.4 (1.5-3.9) times higher than that in a referent group of non-silicotic metal miners. Age- and smoking-adjusted rates in silicotics were 3.9 (2.4-6.4) times higher than that in metal miners. This analysis effectively controls for confounding by age, cigarette smoking, and exposure to other known occupational carcinogens, and it is unlikely that other correlates of silica exposure could explain the excess lung cancer mortality in the silicotics.     

Differential respirable dust related lung function effects between current and former South African coal miners

Dust-related dose-response decrements in lung function among coal miners have been reported in several studies, with varying magnitudes across populations. Few studies have compared differences between current and former coal miners. No studies on dose response relationships with lung function have been conducted in South African coal mines, one of the top three producers of coal internationally. The objectives of this study were (1) to describe the relationship between respirable dust exposure and lung function among current and former South African coal miners and to determine whether differential dust related effects were present between these employment categories; (2) to examine dust related dose response relationships, controlling for potential confounding by smoking and a history of tuberculosis (TB). Six hundred and eighty-four current and 188 ex-miners from three bituminous coal mines in Mpumalanga Province were studied. Interviews assessing work histories, smoking profiles and other risk factors were conducted. Work histories were also obtained from company records. Standardised spirometry was performed by trained technicians. Cumulative respirable dust exposure (CDE) estimates were constructed from company-collected sampling and measurements conducted by the researchers. Regression models examined the associations of CDE with per cent predicted FEV₁ and FVC, controlling for smoking, past history of TB and employment status. A statistically significant decline in FEV₁ of 1.1 and 2.2 ml/mg-year/m³ was found in representative 40-year-old, 1.7-m tall current and former miners, respectively. Significant differences were found between the highest and medium exposure categories. Ex-miners had a lower mean per cent predicted lung function than current miners for each cumulative exposure category, suggesting a healthy worker effect. Past history of TB contributed to 21 and 14% declines in per cent predicted FEV₁ and FVC, respectively. Thus, in this cohort, a dose-related decline in lung function was associated with respirable dust exposure, with a magnitude of effect similar to that seen in other studies and important differences between current and former employees. A healthy worker effect may have attenuated the magnitude of this relationship. TB was a significant contributor to lung function loss.     

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.     

CT和高分辨CT对煤工尘肺小阴影和阴影融合及肺气肿诊断的价值

目的 探讨CT和高分辨CT(HRCT)早期检测煤工尘肺小阴影、阴影融合与肺气肿的敏感性和准确性.方法 77例煤工尘肺患者、36例无尘肺煤工和37例健康非煤工接受多层螺旋CT机无间隔胸部容积扫描及HRCT扫描,对所获得的CT图像进行煤工尘肺小阴影密集度分级、平均肺密度值和肺气肿指数测定,并与其X线胸片诊断结果对照.结果 对77例煤工尘肺患者CT和HRCT诊断的尘肺小阴影密集度分级与X线胸片尘肺分期一致性较好(Kappa=0.771,P＜0.01).CT和HRCT诊断尘肺的敏感性达到98.70％,在X线胸片确诊的77例煤工尘肺患者中,CT和HRCT评估76例为煤工尘肺,可疑1例.CT和HRCT从36例X线胸片无尘肺煤工中检出8例(22.22％)达到小阴影密集度1级;从73例Ⅰ～Ⅱ期煤工尘肺患者中,检出26例(35.62％)阴影密集度≥3级,其中3级密集度阴影20例,4级密集度阴影6例;对4例X线胸片Ⅲ期煤工尘肺患者,CT和HRCT与X线胸片诊断结果相同.从113例煤工中,X线胸片检出肺气肿7例(6.19％),CT检出36例(31.86％).CT尘肺小阴影密集度1～2级组的CT平均肺密度值最高,明显高于健康对照组、无尘肺组和小阴影密集度4级组,差异有统计学意义(F1=-45.73、F2=-23.00和F3=57.72,P＜0.01或P＜0.05).结论 从多层螺旋CT获得的CT和HRCT影像,与X线胸片比较,对煤工尘肺小阴影、阴影融合与肺气肿识别的敏感性和准确性均较高,可为煤工尘肺及其并发症的早期诊断提供更先进的手段.     

Prevalence of pneumoconiosis and its relationship to dust exposure in a cohort of U.S. Bituminous coal miners and ex-miners

Information on radiographic evidence of coal workers' pneumoconiosis (CWP) is presented for a group of 3,194 underground bituminous coal miners and ex-miners examined between 1985 and 1988. Prevalence of CWP was related to estimated cumulative dust exposure, age, and rank of coal. On the basis of these data, miners of medium to low rank coal, who work for 40 years at the current federal dust limit of 2 mg/m³, are predicted to have a 1.4% risk of having progressive massive fibrosis on retirement. Higher prevalences are predicted for less severe categories of CWP. Miners in high rank coal areas appear to be at greater risk than those mining medium and low rank coals. Ex-miners who said that they left mining for health-related reasons had higher levels of abnormality compared to current miners.     

Hospital records: An underutilized source of information regarding occupational diseases and exposures

A 1993 study examined the association between pneumoconiosis and cor pulmonale using a computerized data base of hospital records in Ontario (Hospital Medical Records Institute, HMRI). The present investigation was undertaken to confirm the coding of the diagnoses of a subset of the hospital discharges from that study, to determine the validity of the coding of the diagnoses of coal workers' pneumoconiosis (CWP), and to identify work exposure (occupation and industry) information available in hospital records. We sent abstraction forms to hospitals for 521 subjects who were hospitalized for pneumoconiosis, cor pulmonale, or both conditions, requesting information regarding diagnoses, occupation and industry data, and X-ray results. Abstracts were received for 720 (76%) of 944 discharges that were sought. The hospital abstractions confirmed the HMRI coding for 90% of the charts with these conditions, including 63%, 97%, and 96% of discharges for CWP, silicosis, and asbestosis, respectively. Specific dust exposures were indicated in 42% of the charts with a code indicating a diagnosis of CWP, and of these, 67% indicated exposure to coal dust. Of charts with a code indicating a diagnosis of silicosis, 73% with specific dust information indicated silica exposure, and 95% of those for asbestosis indicated exposure to asbestos. Of 34 individuals in this data set known from the Ministry of Labour's Chest Clinic X-ray Surveillance Program of miners to have silicosis, 33 (97%) were diagnosed by the hospitals as having pneumoconiosis, and all but two were silicosis. Hospital records, as reflected by HMRI data, are reliable indicators of cor pulmonale and pneumoconiosis. The agreement with the Chest Clinic's X-ray diagnoses provides additional objective confirmation of the accuracy of the hospital information. There were relatively few cases of silicosis miscoded as CWP. At least for pneumoconioses, hospital records contained information about the exposures that led to these diseases in ∼50% of the cases. However, whether hospital records would prove useful for detecting other work-related conditions that are not pathognomonic of occupation is not known. The importance of taking occupational histories needs continued emphasis in medical education and training. Am. J. Ind. Med. 31:100–106 © 1997 Wiley-Liss, Inc.     

Presence of stable coal radicals in autopsied coal miners' lungs and its possible correlation to coal workers' pneumoconiosis.

Stable coal radicals (SCRs) were detected by electron spin resonance (ESR) spectroscopy in the lung tissue of autopsied coal miners. The SCR concentrations were measured in the lung tissues from 98 coal miners with and without (a) coal workers' pneumoconiosis (CWP), (b) cancer, and (c) a history of cigarette smoking. Concentrations of SCRs were also determined in the lungs of nonminer controls. The SCR concentration was related to longer mining tenure, CWP disease severity, lung cancer, and cigarette smoking. The mean concentration of SCRs in the lung tissues of miners with 30 +/- 1.4 y of coal mining exposure was 5.3 +/- 1.3 x 10(17) spins/g versus controls who had a nondetectable level (less than 10(15) spins/g). An increase in disease severity was accompanied by a progressive increase in SCR concentration. A SCR concentration of 4.8 +/- 0.7 x 10(17) spins/g was found for simple CWP (with moderate coal macules) versus 7.8 +/- 4.6 spins/g lung tissue for complicated CWP (with progressive massive fibrosis). Significantly higher (i.e., 10 x 10(17] concentrations of SCR in the coal miners' lung tissues were associated with an exposure history in the anthracite regions of northeastern Pennsylvania. These results indicate a possible role for SCRs in the disease process. Furthermore, ESR appears to be an adequate methodology for the quantitation of coal dust retained in the lung and for distinguishing exposures to anthracite and/or bituminous coal.     

Airways obstruction, coal mining, and disability.

It has recently been suggested that the inhalation of coal in the absence of complicated coal workers' pneumoconiosis (CWP) or smoking can lead to disabling airways obstruction. The cause of such obstruction has been variously attributed to emphysema or bronchitis. The frequency of significant airways obstruction in a group of United States coal miners seeking compensation for occupationally induced pulmonary impairment was therefore determined. In a sample of 611 "Black Lung" claimants there was only one subject who was a non-smoker and who in the absence of other non-occupationally related diseases,--for example, asthma and bronchiectasis--had sufficient airways obstruction to render it difficult for him to carry out hard labour. An alternative explanation for his reduced ventilatory capacity other than coal dust or smoking may be available. If the inhalation of coal dust in the absence of smoking and complicated CWP ever induces sufficient ventilatory impairment to preclude a miner from working, it is indeed rare.