Resurgence of Progressive Massive Fibrosis in Coal Miners — Eastern Kentucky, 2016

David J. Blackley, DrPH; James B. Crum, DO; Cara N. Halldin, PhD; Eileen Storey, MD; A. Scott Laney, PhD

Disclosures

Morbidity and Mortality Weekly Report. 2016;65(49):1385-1389. 

In This Article

Abstract and Introduction

Introduction

Coal workers' pneumoconiosis, also known as "black lung disease," is an occupational lung disease caused by overexposure to respirable coal mine dust. Inhaled dust leads to inflammation and fibrosis in the lungs, and coal workers' pneumoconiosis can be a debilitating disease. The Federal Coal Mine Health and Safety Act of 1969 (Coal Act),* amended in 1977, established dust limits for U.S. coal mines and created the National Institute for Occupational Safety and Health (NIOSH)–administered Coal Workers' Health Surveillance Program with the goal of reducing the incidence of coal workers' pneumoconiosis and eliminating its most severe form, progressive massive fibrosis (PMF), which can be lethal. The prevalence of PMF fell sharply after implementation of the Coal Act and reached historic lows in the 1990s, with 31 unique cases identified by the Coal Workers' Health Surveillance Program during 1990–1999. Since then, a resurgence of the disease has occurred, notably in central Appalachia (Figure 1).[1,2] This report describes a cluster of 60 cases of PMF identified in current and former coal miners at a single eastern Kentucky radiology practice during January 2015–August 2016. This cluster was not discovered through the national surveillance program. This ongoing outbreak highlights an urgent need for effective dust control in coal mines to prevent coal workers' pneumoconiosis, and for improved surveillance to promptly identify the early stages of the disease and stop its progression to PMF.

Figure 1.

Prevalence of progressive massive fibrosis (PMF)* among underground-working coal miners with ≥25 years of underground mining tenure — Coal Workers' Health Surveillance Program, Kentucky, Virginia, and West Virginia, 1974–2015
Source: Blackley DJ, Halldin CN, Laney AS. Resurgence of a debilitating and entirely preventable respiratory disease among working coal miners. Am J Respir Crit Care Med 2014;190:708–9. Adapted with permission.
*Data are 5-year moving average (e.g., data plotted for 1974 = [PMF1970 + PMF1971 + PMF1972 + PMF1973 + PMF1974]/[Total participants1970–1974]); surveillance is conducted on a 5-year national cycle.

On June 9, 2016, a radiologist contacted NIOSH to report a sharp increase during the past 2 years in the number of PMF cases among patients who were coal miners seen at his practice serving the easternmost counties of Kentucky. The radiologist requested assistance in conducting an investigation and developing and implementing interventions to reduce the prevalence of disease in the community. NIOSH personnel traveled to Pike County, Kentucky, to assist with the investigation. A case of practice-identified PMF was defined as an International Labor Office classification of large opacity category A, B, or C pneumoconiosis (PMF) in a current or former coal miner receiving a chest radiograph from a single radiology practice in Pike County, Kentucky, during January 1, 2015–August 17, 2016, with completed radiograph classification and occupational history forms. All radiographic classifications were performed by the reporting radiologist, who is an experienced, board-certified radiologist and a NIOSH-certified B Reader (i.e., a physician certified by NIOSH as proficient in classifying radiographs of pneumoconioses).[3]

Sixty male patients who were active or former coal miners had radiographic findings consistent with PMF, including 49 (82%) whose radiographs were taken during 2016. Fifty-six (93%) patients were residents of Kentucky; 48 (86%) of the 56 resided in four contiguous counties (Floyd, Knott, Letcher, and Pike) in the southeastern part of the state that are part of the central Appalachian coalfield. The mean age of patients was 60.3 years (range = 44.9–77.4 years; median = 59.4 years). The mean coal mining tenure was 29.2 years (range = 15–47 years; median = 30.0 years). Thirty-one patients (52%) were determined to have category A PMF (one or more large opacities each >10 mm in diameter with combined dimension ≤50 mm); 23 (38%) had category B (combined dimension >50 mm but not exceeding equivalent area of right upper lung zone); and six (10%) had category C (size larger than category B).§ All 60 patients had radiographic evidence of pneumoconiosis, including 12 (20%) with a small opacity profusion classified as major category 1, 30 (50%) classified as major category 2, and 18 (30%) classified as major category 3. Seven patients had large, rounded opacities, a finding associated with silicosis lung pathology.[4] Twenty-six patients reported being roof bolters (persons who install the bolts that support the roof of an underground coal mine) for most of their careers, and 20 reported being operators of continuous miners, a type of mining machine that produces a constant flow of coal or other solid material from the working face of the mine (Figure 2).

Figure 2.

Photographs of workers and equipment under typical conditions in an underground coal mine*
*A. Two miners use a roof-bolting machine to install the bolts that support the roof of an underground coal mine. B. A continuous miner machine extracts coal from the mine face with a rotating drum.

*http://arlweb.msha.gov/solicitor/coalact/69act.htm.
PMF is a fibrotic pneumoconiotic lesion at least 1 cm in diameter; both coal workers' pneumoconiosis and silicosis can progress to PMF.
§Radiographs for the pneumoconioses are classified by small opacity profusion and large opacity size, compared with standard radiograph images from the International Labour Office. Large opacities are classified as category A, B, or C. Small opacity profusion is classified into four major categories (0, 1, 2, 3), with category 1 or higher considered to be radiographic evidence of pneumoconiosis (http://www.cdc.gov/niosh/topics/chestradiography/breader.html).

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