SAN DIEGO -- Despite stricter rules aimed at reducing dust levels from coal extraction, there has been an increase in incidence of a particularly deadly form of black lung disease among the nation's coal miners, researchers reported here.
The confirmation of an increase in progressive massive fibrosis (PMF) across the coal mining industry follows several reports of outbreaks in isolated coal mining regions, including a 2016 CDC report of 60 PMF cases identified at a single radiology clinic in eastern Kentucky.
Earlier this year, the National Institute for Occupational Safety and Health reported more than 550 cases of PMF occurring in three clinics in southwestern Virginia since 2013 -- the largest cluster of advanced black lung disease ever reported in the U.S.
The newly reported analysis of U.S. Department of Labor data on coal miners collected since 1970 identified 4,679 cases of PMF, with half occurring among miners presenting for evaluation after 2000.
The analysis was presented May 22 at ATS 2018, the annual international conference of the American Thoracic Society.
"We have known about the clusters of PMF cases, but this study represents the first systematic attempt to assess the burden of PMF in former miners," the study's lead researcher, Kirsten Almberg, PhD, of the University of Illinois at Chicago, told ֱ.
The show a significant increase in cases during the past 2 decades, relative to the previous 20 to 30 years, her team found.
In 2014, the Mine Safety Health Administration lowered acceptable breathable dust levels at coal mines from 2.0 to 1.5 per cubic meter of air. Almberg said the resurgence in PMF may reflect mine conditions before these stricter standards went into effect.
The change may also be influenced by changes in mining practices in recent decades, she said. Current mining practices, such as surface mining, typically expose miner to high levels of rock dust, including crystalline silica dust. "Silica is much more toxic to the lung than coal dust. And it is now profitable to sort out coal from rock, so that is increasingly part of the process."
In an effort to better understand the impact of silica dust exposure on the PMF resurgence, Almberg and colleagues are now conducting a study to compare the mineral composition of lung dust from biopsied or extracted tissue of contemporary miners with PMF with stored lung autopsy samples from miners who died of black lung disease 40 or 50 years ago.
"Once we start analyzing the samples, we should be able to see if the silica levels are significantly higher."
Despite the cause, the resurgence in PMF is alarming: "This is a totally preventable disease," Almberg said. "If you don't have the dust exposure, you won't get the disease. So every case of PMF is a failure of the system to protect these coal miners."
Another of the co-authors, Robert Cohen, MD, of the University of Chicago, discussed recent clusters of PMF among coal miners in a separate session at the conference devoted to lung disease risks associated with energy extraction.
"We are seeing resurgent coal mine lung disease, and it's not a relic of the past or something we learned about in medical school," he said.
Active surveillance has not been particularly effective in identifying PMF cases, in part because participation in federally mandated surveillance programs is low among active coal miners, he noted.
"We are finding many of these cases after people have been laid off or after the mine in their area has closed. People don't participate because of fear of job loss and fear of knowing. And sometimes there is a certain amount of mistrust of the government and government programs."
The researchers recently linked black lung compensation claims to surveillance data from the Coal Workers Health Surveillance Program to see if people who applied f0r benefits at the end of their careers had participated in the surveillance program while they were still working in the mines. The results showed that 39% of miners who applied for black lung benefits had never participated in surveillance during their careers.
Also at the session, a fourth-generation coal miner, William "Cotton" Jarrell of Peabody Energy, a Fortune 500 coal company, who now works in mining safety, addressed the challenge of getting miners to seek medical attention: "We don't want to know, so a lot of us just don't go to doctors," he said.
"You can help us by not letting us cancel appointments. Instead of having a receptionist do it, the doctor should pick up the phone and call us with a simple 'Hey buddy, I need you to get in for this appointment.' That would make a huge difference. And if that doesn't work call our wife. She'll get us in there. And as a last resort, call and tell us you're disappointed. We hate to disappoint people. If you tell us you're disappointed that we missed an appointment, I guarantee you we will make the next one."
Primary Source
American Thoracic Society
Almberg K, et al "Resurgence of progressive massive fibrosis in U.S. coal Miners filing for federal black lung program benefits" ATS 2018; Abstract A6064.