Characterizing Lung Particulates Using Quantitative Microscopy in Coal Miners With Severe Pneumoconiosis.

CONTEXT.­: Current approaches for characterizing retained lung dust using pathologists' qualitative assessment or scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) have limitations. OBJECTIVE.­: To explore polarized light microscopy coupled with image-processing software, termed quantitative microscopy-particulate matter (QM-PM), as a tool to characterize in situ dust in lung tissue of US coal miners with progressive massive fibrosis. DESIGN.­: We developed a standardized protocol using microscopy images to characterize the in situ burden of birefringent crystalline silica/silicate particles (mineral density) and carbonaceous particles (pigment fraction). Mineral density and pigment fraction were compared with pathologists' qualitative assessments and SEM/EDS analyses. Particle features were compared between historical (born before 1930) and contemporary coal miners, who likely had different exposures following changes in mining technology. RESULTS.­: Lung tissue samples from 85 coal miners (62 historical and 23 contemporary) and 10 healthy controls were analyzed using QM-PM. Mineral density and pigment fraction measurements with QM-PM were comparable to consensus pathologists' scoring and SEM/EDS analyses. Contemporary miners had greater mineral density than historical miners (186 456 versus 63 727/mm3; P = .02) and controls (4542/mm3), consistent with higher amounts of silica/silicate dust. Contemporary and historical miners had similar particle sizes (median area, 1.00 versus 1.14 µm2; P = .46) and birefringence under polarized light (median grayscale brightness: 80.9 versus 87.6; P = .29). CONCLUSIONS.­: QM-PM reliably characterizes in situ silica/silicate and carbonaceous particles in a reproducible, automated, accessible, and time/cost/labor-efficient manner, and shows promise as a tool for understanding occupational lung pathology and targeting exposure controls.

Pathologic Findings in Severe Coal Workers' Pneumoconiosis in Contemporary US Coal Miners.

CONTEXT.­: The pathology of coal workers' pneumoconiosis (CWP) and its most severe form-progressive massive fibrosis (PMF)-in US coal miners has changed in recent years. Severe disease is occurring in younger miners and has been linked to an increase in silica dust exposure. OBJECTIVE.­: To update the description of the pathologic features of CWP in contemporary miners compared to historical miners. DESIGN.­: This study is a retrospective expert classification of lung tissue from 85 historical and contemporary coal miners with PMF. Significant pathologic features were scored by using a standardized instrument with consensus achieved for major findings, including newly defined categories of PMF as coal-type, mixed-type, and silica-type. RESULTS.­: Pathologic features associated with silica dust exposure, including silica-type PMF, mineral dust alveolar proteinosis (MDAP), and immature (early stage) silicotic nodules were increased in contemporary miners. Detailed descriptions of the pathology of contemporary CWP with illustrative figures are provided. CONCLUSIONS.­: Silica-related pathologies are more common in contemporary miners. Severe forms of CWP can be detected by subtyping PMF lesions (if present) or by identification of mature and immature silicotic nodules, coal mine dust-related alveolar proteinosis, and severe inflammation in coal miners' lungs. Silica-type PMF cases showed significantly higher levels of MDAP than either mixed- or coal-type PMF (P < .001). High profusion of birefringent silica/silicate particles was observed more frequently in cases with immature (early stage) silicotic nodules (P = .04). Severe inflammation was also significantly increased in contemporary miners (P = .03). Our findings underscore the urgent need to revise current exposure limits and monitoring of respirable crystalline silica in US coal mines.

Historical shift in pathological type of progressive massive fibrosis among coal miners in the USA.

BACKGROUND: Pneumoconiosis among coal miners in the USA has been resurgent over the past two decades, despite modern dust controls and regulatory standards. Previously published studies have suggested that respirable crystalline silica (RCS) is a contributor to this disease resurgence. However, evidence has been primarily indirect, in the form of radiographic features. METHODS: We obtained lung tissue specimens and data from the National Coal Workers' Autopsy Study. We evaluated specimens for the presence of progressive massive fibrosis (PMF) and used histopathological classifications to type these specimens into coal-type, mixed-type and silica-type PMF. Rates of each were compared by birth cohort. Logistic regression was used to assess demographic and mining characteristics associated with silica-type PMF. RESULTS: Of 322 cases found to have PMF, study pathologists characterised 138 (43%) as coal-type, 129 (40%) as mixed-type and 55 (17%) as silica-type PMF. Among earlier birth cohorts, coal-type and mixed-type PMF were more common than silica-type PMF, but their rates declined in later birth cohorts. In contrast, the rate of silica-type PMF did not decline in cases from more recent birth cohorts. More recent year of birth was significantly associated with silica-type PMF. CONCLUSIONS: Our findings demonstrate a shift in PMF types among US coal miners, from a predominance of coal- and mixed-type PMF to a more commonly encountered silica-type PMF. These results are further evidence of the prominent role of RCS in the pathogenesis of pneumoconiosis among contemporary US coal miners.

Mining Tenure and Job Duties Differ Among Contemporary and Historic Underground Coal Miners With Progressive Massive Fibrosis.

OBJECTIVE: To characterize differences in mining jobs and tenure between contemporary (born 1930+, working primarily with modern mining technologies) and historic coal miners with progressive massive fibrosis (PMF). METHODS: We classified jobs as designated occupations (DOs) and non-DOs based on regulatory sampling requirements. Demographic, occupational characteristics, and histopathological PMF type were compared between groups. RESULTS: Contemporary miners ( n = 33) had significantly shorter mean total (30.4 years vs 37.1 years, P = 0.0006) and underground (28.8 years vs 35.8 years, P = 0.001) mining tenure compared with historic miners ( n = 289). Silica-type PMF was significantly more common among miners in non-DOs (30.1% vs 15.8%, P = 0.03) and contemporary miners (58.1% vs 15.2%, P < 0.0001). CONCLUSIONS: Primary jobs changed over time with the introduction of modern mining technologies and likely changed exposures for workers. Elevated crystalline silica exposures are likely in non-DOs and require attention.

Pathology and Mineralogy Demonstrate Respirable Crystalline Silica Is a Major Cause of Severe Pneumoconiosis in U.S. Coal Miners.

Rationale: The reasons for resurgent coal workers' pneumoconiosis and its most severe forms, rapidly progressive pneumoconiosis and progressive massive fibrosis (PMF), in the United States are not yet fully understood. Objectives: To compare the pathologic and mineralogic features of contemporary coal miners with severe pneumoconiosis with those of their historical counterparts. Methods: Lung pathology specimens from 85 coal miners with PMF were included for evaluation and analysis. We compared the proportion of cases with pathologic and mineralogic findings in miners born between 1910 and 1930 (historical) with those in miners born in or after 1930 (contemporary). Results: We found a significantly higher proportion of silica-type PMF (57% vs. 18%; P < 0.001) among contemporary miners compared with their historical counterparts. Mineral dust alveolar proteinosis was also more common in contemporary miners compared with their historical counterparts (70% vs. 37%; P < 0.01). In situ mineralogic analysis showed that the percentage (26.1% vs. 17.8%; P < 0.01) and concentration (47.3 × 108 vs. 25.8 × 108 particles/cm3; P = 0.036) of silica particles were significantly greater in specimens from contemporary miners compared with their historical counterparts. The concentration of silica particles was significantly greater when silica-type PMF, mineral dust alveolar proteinosis, silicotic nodules, or immature silicotic nodules were present (P < 0.05). Conclusions: Exposure to respirable crystalline silica appears causal in the unexpected surge of severe disease in contemporary miners. Our findings underscore the importance of controlling workplace silica exposure to prevent the disabling and untreatable adverse health effects afflicting U.S. coal miners.

Non-diabetic ketoacidosis associated with a low carbohydrate, high fat diet in a postpartum lactating female.

A 31-year old non-diabetic woman presented to our hospital with symptoms of dehydration, drowsiness, fatigue, shortness of breath and vomiting present for two consecutive days prior to admission. She had started a low carbohydrate, high fat (LCHF) diet to induce weight loss while breastfeeding her 4-month-old child 2 weeks prior to admission. The patient was found to have a severely high anion gap metabolic acidosis. It was determined to be due to ketoacidosis, which was as a result of carbohydrate restriction in the presence of increased metabolic demands related with the synthesis and secretion of milk. She denied alcohol use or ingestion of any drugs prior to admission. The patient underwent dialysis and received insulin, 5% dextrose water alongside a well-balanced diet with adequate calories. All abnormal laboratory results normalized and follow-up visits were done. Lactating women are at risk of developing ketoacidosis due to high metabolic demands of the body to produce milk. LCHF diets may exacerbate the body's demand to meet its milk production requirement and result in ketoacidosis. Health professionals need to be aware of the complications of LCHF diet in this population to prevent mortality associated with this condition.

Effects of commodity on the risk of emphysema in South African miners.

PURPOSE: To examine associations between mine commodity such as coal, platinum, or diamonds and emphysema among South African miners at autopsy. METHODS: We examined the association between mine commodity and emphysema using the Pathology Automation (PATHAUT) database, 1975-2014. Exposure was characterized as longest tenure in each commodity. We constructed separate multivariable logistic regression models for black and white miners. Smoking was assessed in a sub-analysis of white miners. RESULTS: Among black miners, coal mining was significantly associated with increased odds of emphysema [OR = 2.39 (95% CI 1.86, 3.07)] when compared to gold mining. Asbestos was also associated with significantly increased odds of emphysema among black miners [OR = 1.47 (95% CI 1.01, 2.12)]. No associations between commodity and emphysema were observed among white miners. Cumulative years of exposure and age at death were significant predictors for emphysema for both black and white miners. Smoking was a significant predictor of emphysema in the sub-analysis of white miners with smoking information, but no effect of commodity was observed. CONCLUSIONS: We observed a significant association between coal mining and emphysema among black miners. Adverse health effects of coal mining are evidenced by more than twofold increase in emphysema among black coal miners compared to gold miners. This suggests that South African Coal miners are exposed to high dust concentrations or more damaging components compared to other commodities, resulting in elevated risk of emphysema.

Occupational emphysema in South African miners at autopsy; 1975-2014.

PURPOSE: To determine the associations between exposure duration, measured by employment tenure, and emphysema presence and severity in black and white South African miners at autopsy. METHODS: We examined the association between mining tenure and emphysema presence or severity using the Pathology Automation (PATHAUT) database, 1975-2014. We used logistic regression models adjusted for age, tuberculosis, HIV status, and year of death. The effect of smoking on the presence and severity of emphysema was assessed in a sub-analysis of white miners. RESULTS: Mining tenure was significantly associated with increased odds of emphysema presence in black and white miners. For every 10-year increase in tenure, black miners had a 17% increase in odds of emphysema [ORblack = 1.17 (95% CI 1.12, 1.22)] and white miners had a 7% increase in odds of the disease [ORwhite = 1.07 (95% CI 1.04, 1.10)]. Tenure was significantly associated with emphysema severity among black miners [ORseverity = 1.16 (95% CI 1.06, 1.28)]. In a subset of white miners with smoking status, we found that for every 10 years of tenure, there is a significant increase in odds of emphysema presence and severity [ORpresence = 1.14 (95% CI 1.09, 1.19); ORseverity = 1.06 (95% CI 1.00, 1.10)] after adjusting for smoking. CONCLUSIONS: We observed a significant relationship between mining tenure and emphysema severity among South African miners in PATHAUT between 1975 and 2014. This relationship was evident in multi-variable analyses adjusted for smoking among white miners. Hazards from long term exposure to inhaled mineral dust leading to lung damage (silicosis, fibrosis, COPD) is evident and warrants further improvement of working conditions and prevention measures in South African mines especially for black workers. Further research is needed to determine if there is an effect of TB and HIV co-infection on the development of emphysema.

Asbestos-related diseases in mineworkers: a clinicopathological study.

The accurate diagnosis of asbestos-related diseases is important because of past and current asbestos exposures. This study evaluated the reliability of clinical diagnoses of asbestos-related diseases in former mineworkers using autopsies as the reference standard. Sensitivity, specificity, positive predictive value and negative predictive value were calculated. The 149 cases identified had clinical examinations 0.3-7.4 years before death. More asbestos-related diseases were diagnosed at autopsy rather than clinically: 77 versus 52 for asbestosis, 27 versus 14 for mesothelioma and 22 versus 3 for lung cancer. Sensitivity and specificity values for clinical diagnoses were 50.6% and 81.9% for asbestosis, 40.7% and 97.5% for mesothelioma, and 13.6% and 100.0% for lung cancer. False-negative diagnoses of asbestosis were more likely using radiographs of acceptable (versus good) quality and in cases with pulmonary tuberculosis at autopsy. The low sensitivity values are indicative of the high proportion of false-negative diagnoses. It is unlikely that these were the result of disease manifestation between the last clinical assessment and autopsy. Where clinical features suggest asbestos-related diseases but the chest radiograph is negative, more sophisticated imaging techniques or immunohistochemistry for asbestos-related cancers should be used. Autopsies are useful for the detection of previously undiagnosed and misdiagnosed asbestos-related diseases, and for monitoring clinical practice and delivery of compensation.

38 years of autopsy findings in South African mine workers.

BACKGROUND: South African miners have a statutory right to autopsies for occupational lung disease compensation. These autopsies also provide information for research and surveillance. METHODS: Cardio-respiratory organs are removed where miners die and are examined at the National Institute for Occupational Health. We extracted data from the PATHAUT database and described key demographic, exposure and disease trends (1975-2013). RESULTS: Of 109,101 autopsies, 72,348 (66.3%) were black, and 34,794 (31.9%) were white miners. Autopsies declined from over 3,000 (1975-1998) to 1,118 in 2013. Most were gold miners (74.0%). 78.6% black and 13.2% white miners died while in employment. Overall proportions of silicosis and pulmonary tuberculosis were 12.0% and 13.0% in black, and 20.5% and 2.4% in white miners, respectively. Disease increased over time. CONCLUSIONS: High levels of disease persist. Black ex-miners are underrepresented, indicating a need for strategies to improve awareness and provision of autopsy facilities in labor-sending areas.