Coal workers’ pneumoconiosis, also known as “black lung disease,” has reappeared in the U.S. in “alarming” numbers, according to the National Institute for Occupational Safety and Health (NIOSH).

Black lung is a disabling, often fatal occupational disease caused by overexposure to respirable coal mine dust.

A recent report in a recent CDC MMWR bulletin 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 – something which the report’s authors say argues for improved surveillance to promptly identify the early stages of the disease and stop its progression to PMF.

Radiologist calls NIOSH for help

The spike appeared on NIOSH’s radar when a radiologist contact the agency 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. 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.

Why this particular increase? NIOSH isn’t yet sure of the factor or combination of factors that caused it, and of whether there are more unrecognized cases in neighboring coal mining regions. Because PMF takes years to become manifest, the specific exposures or mining practices that led to these cases are also unknown.

Mining practices, health insurance worries might be factors

New or modified mining practices such as “slope mining” might be causing hazardous dust exposures. Slope mining involves teams of miners operating continuous miner machines, designed to cut coal and other soft rock, to cut shafts through hundreds of feet of sandstone to reach underground coal seams.

Another factor might be recent industry trends. There’s been a steep decline in coal production and coal miner employment. Miners might feel unsure about the future of health care resources and may be seeking radiographs in greater numbers.

Coal Act reduced incidence - for awhile

The number of cases of the most severe form of black lung, progressive massive fibrosis (PMF), dropped sharply after implementation of the Federal Coal Mine Health and Safety Act of 1969 (Coal Act), which established dust limits for U.S. coal mines. (The Coal Act also created the NIOSH–administered Coal Workers’ Health Surveillance Program.) After an historic low of 31 cases from 1990-1999, PMF began to be diagnosed in greater numbers in subsequent years.

The study’s authors are David J. Blackley, DrPH; James B. Crum, DO; Cara N. Halldin, PhD; Eileen Storey, MD; and A. Scott Laney, PhD.