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Abstract Coal mining remains a sizable industry, with millions of working and retired coal miners worldwide. This article provides an update on recent advances in the understanding of respiratory health issues in coal miners and focuses on the spectrum of disease caused by inhalation of coal mine dust, termed coal mine dust lung disease. In addition to the historical interstitial lung diseases (coal worker’s pneumoconiosis, silicosis, and mixed dust pneumoconiosis), coal miners are at risk for dust-related diffuse fibrosis and chronic airway diseases, including emphysema and chronic bronchitis. Recent recognition of rapidly progressive pneumoconiosis in younger miners, mainly in the eastern United States, has increased the sense of urgency and the need for vigilance in medical research, clinical diagnosis, and exposure prevention. Given the risk for disease progression even after exposure removal, along with few medical treatment options, there is an important role for chest physicians in the recognition and management of lung disease associated with work in coal mining.

ObjectivesEpidemiological reports since 2000 have documented increased prevalence and rapid progression of pneumoconiosis among underground coal miners in the United States. To investigate a possible role of silica exposure in the increase, we examined chest x-rays (CXRs) for specific abnormalities (r-type small opacities) known to be associated with silicosis lung pathology.MethodsUnderground coal miners are offered CXRs every 5 years. Abnormalities consistent with pneumoconiosis are recorded by National Institute for Occupational Safety and Health (NIOSH) B Readers using the International Labour Organization Classification of Radiographs of Pneumoconioses. CXRs from 1980 to 2008 of 90 973 participating miners were studied, focussing on reporting of r-type opacities (small rounded opacities 3–10 mm in diameter). Log binomial regression was used to calculate prevalence ratios adjusted for miner age and profusion category.ResultsAmong miners from Kentucky, Virginia and West Virginia, the proportion of radiographs showing r-type opacities increased during the 1990s (prevalence ratio (PR) 2.5; 95% CI 1.7 to 3.7) and after 1999 (PR 4.1; 95% CI 3.0 to 5.6), compared to the 1980s (adjusted for profusion category and miner age). The prevalence of progressive massive fibrosis in 2000–2008 was also elevated compared to the 1980s (PR 4.4; 95% CI 3.1 to 6.3) and 1990s (PR 3.8; 95% CI 2.1 to 6.8) in miners from Kentucky, Virginia and West Virginia.ConclusionsThe increasing prevalence of pneumoconiosis over the past decade and the change in the epidemiology and disease profile documented in this and other recent studies imply that US coal miners are being exposed to excessive amounts of respirable crystalline silica.

OBJECTIVE:The National Institute for Occupational Safety and Health (NIOSH) B Reader Program provides the opportunity for physicians to demonstrate proficiency in the International Labour Office (ILO) system for classifying radiographs of pneumoconioses. We summarize trends in participation and examinee attributes and performance during 1987 to 2018. METHODS:Since 1987, NIOSH has maintained details of examinees and examinations. Attributes of examinees and their examination performance were summarized. Simple linear regression was used in trend analysis of passing rates over time. RESULTS:The mean passing rate for certification and recertification for the study period was 40.4% and 82.6%, respectively. Since the mid-1990s, the number of B Readers has declined and the mean age and years certified have increased. CONCLUSIONS:To address the declining B Reader population, NIOSH is currently taking steps to modernize the program and offer more opportunities for training and testing.

Lung function level and decline are each predictive of morbidity and mortality. Evaluation of the combined effect of these measurements may help further identify high-risk groups. Using Copenhagen City Heart Study longitudinal spirometry data (n = 10,457), 16–21 year risks of chronic obstructive pulmonary disease (COPD) morbidity, COPD or coronary heart disease mortality, and all-cause mortality were estimated from combined effects of level and decline in forced expiratory volume in one second (FEV 1 ). Risks were evaluated using Cox proportional hazards models for individuals grouped by combinations of baseline predicted FEV 1 and quartiles of slope. Hazard ratios (HR) and 95 % confidence intervals (CI) were estimated using stratified analysis by gender, smoking status, and baseline age (≤45 and >45). For COPD morbidity, quartiles of increasing FEV 1 decline increased HRs (95 % CI) for individuals with FEV 1 at or above the lower limit of normal (LLN) but below 100 % predicted, reaching 5.11 (2.58–10.13) for males, 11.63 (4.75–28.46) for females, and 3.09 (0.88–10.86) for never smokers in the quartile of steepest decline. Significant increasing trends were also observed for mortality and in individuals with a baseline age ≤45. Groups with 'normal' lung function (FEV 1 at or above the LLN) but excessive declines (fourth quartile of FEV 1 slope) had significantly increased mortality risks, including never smokers and individuals with a baseline age ≤45.

Objective: To investigate occupational latex allergy in health care workers (HCWs) before and after an intervention designed to reduce latex allergen exposure from gloves. Methods: Latex antigen concentrations in work area air ducts were measured before the intervention. Symptoms and latex sensitization were monitored annually before and after the intervention in 805 HCWs, using questionnaires and skin prick testing. Results: The prevalence of latex sensitization before the intervention correlated with air duct latex antigen measurements, for HCWs exposed to low (9/413,2%), intermediate (23/292, 8%), and high (11/67, 16%) antigen levels, P < 0.0001. After the intervention, new latex sensitization rates declined 16-fold, and 25% of previously sensitized employees reverted to negative skin tests. Conclusion: Airborne antigen exposure is a major source of latex sensitization among HCWs. Use of powder-free latex gloves markedly reduces the risk of sensitization.

Abstract Rationale Recent reports of progressive massive fibrosis and rapidly progressive pneumoconiosis in U.S. coal miners have raised concerns about excessive exposures to coal mine dust, despite reports of declining dust levels. Objectives To evaluate the histologic abnormalities and retained dust particles in available coal miner lung pathology specimens, and to compare these findings with those derived from corresponding chest radiographs. Methods Miners with severe disease and available lung tissue were identified through investigator outreach. Demographic as well as smoking and work history information was obtained. Chest radiographs were interpreted according to the International Labor Organization classification scheme to determine if criteria for rapidly progressive pneumoconiosis were confirmed. Pathology slides were scored by three expert pulmonary pathologists using a standardized nomenclature and scoring system. Measurements and Main Results Thirteen cases were reviewed, many of which had features of accelerated silicosis and mixed dust lesions. Twelve had progressive massive fibrosis, and 11 had silicosis. Only four had classic lesions of simple coal workers’ pneumoconiosis. Four had diffuse interstitial fibrosis with chronic inflammation, and two had focal alveolar proteinosis. Polarized light microscopy revealed large amounts of birefringent mineral dust particles consistent with silica and silicates; carbonaceous coal dust was less prominent. On the basis of chest imaging studies, specimens with features of silicosis were significantly associated (P = 0.047) with rounded (type p, q, or r) opacities, whereas grade 3 interstitial fibrosis was associated (P = 0.02) with the presence of irregular (type s, t, or u) opacities. Conclusions Our findings suggest that rapidly progressive pneumoconiosis in these miners was associated with exposure to coal mine dust containing high concentrations of respirable silica and silicates.

BackgroundPneumoconiosis 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.MethodsWe 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.ResultsOf 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.ConclusionsOur 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.

ObjectivesIn 2010, 29 coal miners died due to an explosion at the Upper Big Branch (UBB) mine in West Virginia, USA. Autopsy examinations of 24 individuals with evaluable lung tissue identified 17 considered to have coal workers’ pneumoconiosis (CWP). The objectives of this study were to characterise histopathological findings of lung tissue from a sample of UBB fatalities and better understand the respirable dust concentrations experienced by these miners at UBB relative to other US coal mines.MethodsOccupational pulmonary pathologists evaluated lung tissue specimens from UBB fatalities for the presence of features of pneumoconiosis. Respirable dust and quartz samples submitted for regulatory compliance from all US underground coal mines prior to the disaster were analysed.ResultsFamilies of seven UBB fatalities provided consent for the study. Histopathologic evidence of CWP was found in all seven cases. For the USA, central Appalachia and UBB, compliance dust samples showed the geometric mean for respirable dust was 0.468, 0.420 and 0.518 mg/m3, respectively, and respirable quartz concentrations were 0.030, 0.038 and 0.061 mg/m3. After adjusting for quartz concentrations, UBB exceeded the US permissible exposure limit (PEL) for respirable dust in 28% of samples.ConclusionsAlthough higher than average respirable dust and quartz levels were observed at UBB, over 200 US underground coal mines had higher dust concentrations than UBB and over 100 exceeded the PEL more frequently. Together with lung histopathological findings among UBB fatalities, these data suggest exposures leading to CWP in the USA are more prevalent than previously understood.

BACKGROUND:Coal workers’ pneumoconiosis (CWP) steadily declined among US miners following dust control regulations in 1970. In 2000, severe forms of this disease reemerged among young miners, and are well described among working—but not former—miners. METHODS:Black lung benefits program (BLBP) data (2001 to 2013) were used to estimate respiratory disease burden among former miners including(1) CWP (simple; advanced CWP, and progressive massive fibrosis [CWP/PMF]); and (2) respiratory impairment (FEV1 percent referencemild, moderate, ≥moderately-severe). RESULTS:Among 24,686 claimants, 8.5% had advanced CWP/PMF; prevalence was highest among younger (less than or equal to 56 years10.8%) and older (greater than 70 years8.4%) miners and those who began work after versus before 1970 (8.3% vs. 4.0%). CONCLUSIONS:BLBP claims provide potentially useful data for monitoring the burden and severity of coal mine dust lung disease, and assessing efficacy of protective regulations.

Diisocyanates, a group of highly reactivechemicals, have frequently been associated with occupational asthma. Weevaluated respiratory health in workers at a new wood productsmanufacturing plant that uses methylene diphenyl diisocyanate (MDI),and was designed and operated with a goal of minimizing workerexposures. Health surveys using standardizedrespiratory questionnaires were done prior to the initial use of diisocyanates in the plant, and semiannually thereafter for a period of2 years. Other testing included occupational and work practicehistories, serial peak flow measurements, spirometry, methacholinechallenge, and measurement of specific IgE antibodies to MDI-albuminconjugate. Of 214 plant employees whoparticipated in at least one health survey, a follow-up survey was alsoavailable from 178 employees (83%). New-onset asthma-like symptoms(NAS) were reported by 15 of 56 workers (27%) in areas with thehighest potential for exposures to liquid MDI monomer and prepolymer, vs 0 of 43 workers in the lowest potential exposure areas(p = 0.001). In the areas with high potential exposure, NAS developedin 47% of workers who had noted MDI skin staining, vs 19% withoutskin stains (p = 0.07). Working around and cleaning up liquid MDIrepresented a significant risk for asthma-like symptoms in both currentsmokers and nonsmokers; work with finished wood products did not. Asthma-like symptoms were associated with variable airflow limitation(odds ratio [OR], 5.0; confidence interval [CI], 1.4 to 18.7) andspecific IgE to MDI-albumin (OR, 3.2; CI, 1.1 to 9.0), but not withskin prick tests to common aeroallergens (OR, 1.1; CI, 0.5 to2.7). During the first 2 years of operation, in a plant designed and operated to control exposure todiisocyanates, the development of asthma-like symptoms was reported ina relatively high proportion of the employees who worked with liquidMDI. To prevent asthma symptoms among workers, careful control of respiratory tract exposures associated with liquid MDI is important, especially during cleanup activities. Strict limitation of skin contactwith diisocyanates may also be necessary.