Respiratory morbidity among U.S. coal miners in states outside of central Appalachia

Racial Differences in Respiratory Impairment, Pneumoconiosis, and Federal Compensation for Western U.S. Indigenous Coal Miners

Rationale: Indigenous populations in the United States face numerous health disparities, but the health of Indigenous workers is less well understood. In a recent surveillance study of active Indigenous coal miners, 3% had coal workers' pneumoconiosis/black lung, and 9% had respiratory impairment. However, occupational lung disease prevalence among Indigenous coal miners has not been directly compared with that among other race/ethnicity groups. Coal miners who are totally disabled from black lung may qualify for U.S. Department of Labor (DOL) compensation benefits, but it is unclear how current federal spirometry criteria affect qualification for Indigenous coal miners.Objectives: To compare findings of pneumoconiosis and respiratory impairment in Indigenous and non-Indigenous coal miners in the western United States and assess federal compensation qualification for Indigenous miners using different spirometry standards.Methods: We used voluntary medical surveillance data from 2002 to 2023 to compare the adjusted odds of pneumoconiosis and respiratory impairment between Indigenous/non-Indigenous coal miners. We examined the proportion of Indigenous miners meeting DOL criteria for federal compensation using different spirometry standards.Results: We identified 691 western U.S. coal miners with at least one year of coal mining employment, 289 Indigenous and 402 non-Indigenous (96% White/Hispanic). Indigenous miners had a greater odds ratio for pneumoconiosis for each additional decade of life (2.47 [95% confidence interval (CI), 1.66-3.68]) compared with non-Indigenous coal miners (1.48 [95% CI, 1.19-1.85]). For each decade, Indigenous coal miners also had a greater adjusted odds ratio for respiratory impairment (1.67 [95% CI, 1.25-2.24]) than non-Indigenous miners (1.06 [95% CI, 0.90-1.25]). Indigenous miners had an additional decline of 71 ml (95% CI, 6-136 ml) in forced expiratory volume in 1 second for each decade of life compared with non-Indigenous coal miners. Using the DOL-mandated Knudson (1976) spirometry standard rather than an Indigenous-specific standard, 6 of 18 (33%) Indigenous miners would not qualify for federal compensation.Conclusions: Indigenous coal miners experience greater adjusted odds for pneumoconiosis and respiratory impairment per decade of life and greater decline in forced expiratory volume in 1 second despite lower smoking rates. Structural inequities exist in federal spirometry requirements for Indigenous miners seeking DOL black lung benefits. Regulatory reform is needed to address barriers to compensation for these underrepresented workers.

Impact of Epidemic Intelligence Service Training in Occupational Respiratory Epidemiology

The Centers for Disease Control and Prevention's Epidemic Intelligence Service (EIS) is a fellowship in applied epidemiology for physicians, veterinarians, nurses, scientists, and other health professionals. Each EIS fellow is assigned to a position at a federal, state, or local site for 2 years of on-the-job training in outbreak investigation, epidemiologic research, surveillance system evaluation, and scientific communication. Although the original focus of the program on the control of infectious diseases remains salient, positions are available for training in other areas of public health, including occupational respiratory disease. In this Perspective, we describe the EIS program, highlight three positions (one federal and two state-based) that provide training in occupational respiratory epidemiology, and summarize trainees' experiences in these positions over a 30-year period. For early-career health professionals interested in understanding and preventing occupational respiratory hazards and diseases, EIS offers a unique career development opportunity.

Prevalence of coal worker's pneumoconiosis: a systematic review and meta-analysis

Global prevalence trend and regional differences of coal worker's pneumoconiosis (CWP) remain unclear. This study aimed to provide systematic and comprehensive evidence for the global prevalence of CWP. Literature research for studies that reported prevalence of CWP was conducted in PubMed, CNKI, and Web of Science. The identified studies were strictly screened according to predetermined inclusion and exclusion criteria. The pooled prevalence of CWP in different periods and regions was calculated. A total of 37 studies were included after screening, and data from the Coal Workers' Health Surveillance Program was additionally included in the meta-analysis. The global pooled prevalence of CWP decreased from 23.33% (95% confidence interval [CI]: 18.03%, 28.62%) before 1970 to 6.00% (95% CI: 4.11%, 7.90%) in 1981-1990, but indicated a rebound (10.35%, 95% CI: 8.08%, 12.62%) in 1991-2000 and finally dropped to 2.29% (95% CI: 2.06%, 2.51%) in 2011-2020. In the recent 30 years, the top three pooled prevalence of CWP was found in Europe, China, and the USA, respectively. Few articles have reported the prevalence in developing regions, but available evidence indicated that the prevalence in developing regions was much higher than that in developed regions. Higher pooled prevalence was observed in studies which reported larger number of miners in collieries, older average age of miners, underground collieries, and longer dust exposure time. The global prevalence of CWP indicates a rebound in 1990s, but the overall trend is downward in the recent 60 years. The prevention and treatment of CWP should be currently emphasized in developing countries.

Understanding the pathogenesis of occupational coal and silica dust-associated lung disease

Workers in the mining and construction industries are at increased risk of respiratory and other diseases as a result of being exposed to harmful levels of airborne particulate matter (PM) for extended periods of time. While clear links have been established between PM exposure and the development of occupational lung disease, the mechanisms are still poorly understood. A greater understanding of how exposures to different levels and types of PM encountered in mining and construction workplaces affect pathophysiological processes in the airways and lungs and result in different forms of occupational lung disease is urgently required. Such information is needed to inform safe exposure limits and monitoring guidelines for different types of PM and development of biomarkers for earlier disease diagnosis. Suspended particles with a 50% cut-off aerodynamic diameter of 10 µm and 2.5 µm are considered biologically active owing to their ability to bypass the upper respiratory tract's defences and penetrate deep into the lung parenchyma, where they induce potentially irreversible damage, impair lung function and reduce the quality of life. Here we review the current understanding of occupational respiratory diseases, including coal worker pneumoconiosis and silicosis, and how PM exposure may affect pathophysiological responses in the airways and lungs. We also highlight the use of experimental models for better understanding these mechanisms of pathogenesis. We outline the urgency for revised dust control strategies, and the need for evidence-based identification of safe level exposures using clinical and experimental studies to better protect workers' health.

Respiratory health of American Indian and Alaska Native coal miners participating in the Coal Workers' Health Surveillance Program, 2014-2019

BACKGROUND

In 2014, a federal rule reduced occupational exposure limits to coal mine dust and expanded medical surveillance eligibility beyond underground miners to surface and contract coal miners. This expansion may have provided an opportunity for more American Indian and Alaska Native (AI/AN) coal miners to participate in screening, since many surface coal mines are located near AI/AN communities and may employ AI/AN miners. Therefore we sought to better understand the respiratory health of AI/AN coal miners by characterizing prevalence of coal workers' pneumoconiosis (CWP), progressive massive fibrosis (PMF), and abnormal lung function in this population.

METHODS

Descriptive analysis of 1405 chest radiographs and 627 spirometry test results for AI/AN miners who participated in the Coal Workers' Health Surveillance Program (CWHSP) during 2014-2019 was conducted.

RESULTS

Most AI/AN miners (0-25+ years of tenure) were western United States residents (82.3%) and active surface miners (76.9%) with no underground tenure. Among miners with at least 10 years of tenure, prevalence of CWP was 3.0%, and of PMF was 0.3%. Lung function abnormalities were seen in 9.0% with primarily restrictive patterns.

CONCLUSIONS

The prevalence of CWP, PMF, and lung function abnormality among active and former AI/AN coal miners was higher than seen in a larger CWHSP study of active western miners working primarily underground with 10+ years of tenure. Interventions that eliminate or control coal mine dust exposure, identify miners with CWP early, and limit respiratory disease progression and complications remain vital for eliminating the preventable adverse health effects of coal mining. Comprehensive demographic data on the coal mining workforce are needed to improve CWHSP participation assessment.

A systematic review and meta-analysis on international studies of prevalence, mortality and survival due to coal mine dust lung disease

BACKGROUND

Coal mine dust lung disease comprises a group of occupational lung diseases including coal workers pneumoconiosis. In many countries, there is a lack of robust prevalence estimates for these diseases. Our objective was to perform a systematic review and meta-analysis of published contemporary estimates on prevalence, mortality, and survival for coal mine dust lung disease worldwide.

METHODS

Systematic searches of PubMed, EMBASE and Web of Science databases for English language peer-reviewed articles published from 1/1/2000 to 30/03/2021 that presented quantitative estimates of prevalence, mortality, or survival for coal mine dust lung disease. Review was conducted per PRISMA guidelines. Articles were screened independently by two authors. Studies were critically assessed using Joanna Briggs Institute tools. Pooled prevalence estimates were obtained using random effects meta-analysis models. Heterogeneity was measured using the I2 statistics and publication bias using Egger's tests.

RESULTS

Overall 40 studies were included, (31 prevalence, 8 mortality, 1 survival). Of the prevalence estimates, fifteen (12 from the United States) were retained for the meta-analysis. The overall pooled prevalence estimate for coal workers pneumoconiosis among underground miners was 3.7% (95% CI 3.0-4.5%) with high heterogeneity between studies. The pooled estimate of coal workers pneumoconiosis prevalence in the United States was higher in the 2000s than in the 1990s, consistent with published reports of increasing prevalence following decades of declining trends. Sub-group analyses also indicated higher prevalence among underground miners, and in Central Appalachia. The mortality studies were suggestive of reduced pneumoconiosis mortality rates over time, relative to the general population.

CONCLUSION

The ongoing prevalence of occupational lung diseases among contemporary coal miners highlights the importance of respiratory surveillance and preventive efforts through effective dust control measures. Limited prevalence studies from countries other than the United States limits our understanding of the current disease burden in other coal-producing countries.

ACR Appropriateness Criteria® Occupational Lung Diseases

Ordering the appropriate diagnostic imaging for occupational lung disease requires a firm understanding of the relationship between occupational exposure and expected lower respiratory track manifestation. Where particular inorganic dust exposures typically lead to nodular and interstitial lung disease, other occupational exposures may lead to isolated small airway obstruction. Certain workplace exposures, like asbestos, increase the risk of malignancy, but also produce pulmonary findings that mimic malignancy. This publication aims to delineate the common and special considerations associated with occupational lung disease to assist the ordering physician in selecting the most appropriate imaging study, while still stressing the importance of a multidisciplinary approach. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Respirable coal mine dust at surface mines, United States, 1982-2017

BACKGROUND

Exposure to respirable coal mine dust can cause pneumoconiosis, an irreversible lung disease that can be debilitating. The mass concentration and quartz mass percent of respirable coal mine dust samples (annually, by occupation, by geographic region) from surface coal mines and surface facilities at U.S. underground mines during 1982-2017 were summarized.

METHODS

Mine Safety and Health Administration (MSHA) collected and analyzed data for respirable dust and a subset of the samples were analyzed for quartz content. We calculated the respirable dust and quartz concentration geometric mean, arithmetic mean, and percent of samples exceeding the respirable dust permissible exposure limit (PEL) of 2.0 mg/m3, and the average percent of quartz content in samples.

RESULTS

The geometric mean for 288 705 respirable dust samples was 0.17 mg/m³ with 1.6% of the samples exceeding the 2.0 mg/m³ PEL. Occupation-specific geometric means for respirable dust in active mining areas were highest among drillers. The geometric mean for respirable dust was higher in central Appalachia compared to the rest of the U.S. The geometric mean for respirable quartz including 54 040 samples was 0.02 mg/m³ with 15.3% of these samples exceeding the applicable standard (PEL or reduced PEL). Occupation-specific geometric means for respirable quartz were highest among drillers.

CONCLUSION

Higher concentrations of respirable dust or quartz in specific coal mining occupations, notably drilling occupations, and in certain U.S. regions, underscores the need for continued surveillance to identify workers at higher risk for pneumoconiosis.

Current Review of Pneumoconiosis Among US Coal Miners

PURPOSE OF REVIEW

This review summarizes recent research on pneumoconiosis in coal workers following the identification of the resurgence of this disease among US coal miners in the early 2000s. We describe the impact of this research and how this has led to increased public attention, benefitting affected miners.

RECENT FINDINGS

The latest research shows that the prevalence of pneumoconiosis, including progressive massive fibrosis, continues to increase, especially in central Appalachia. Contributing factors may include mining of thin coal seams or cutting rock to access coal, which may expose miners to coal mine dust with a higher content of silica and silicates than in the past. The impact of recently implemented changes, such as the reduced occupational exposure limit for respirable coal mine dust and the introduction of continuous personal dust monitors, will likely take years to appropriately evaluate.