Photo: ATS

New research presented Monday at the annual American Thoracic Society Conference shows that the worst form of black lung—a disease most prevalent among coal mine workers—is on the rise, placing recent generations of miners at greater risk of dying from the respiratory disease than earlier ones. And a shift in mining technology several decades back may be at least in part to blame.

Black lung, more formally known as pneumoconiosis, is a respiratory disease that results from breathing in dusts that damage the lungs. A resurgence in black lung came to the attention of medical researchers last year, but this latest information gives us some more specifics on why it’s coming back to haunt Appalachian communities in Virginia, West Virginia, and Pennsylvania.

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A team from the University of Illinois at Chicago and the National Institute for Occupational Safety and Health discussed two separate research projects during the conference, both of which involved analyzing thousands of individual death data records and thousands of lung specimens from deceased coal mine workers between the years 1970 and 2016.

They found that higher proportions of miners born after 1940 were dying from a severe form black lung that’s been increasing since 1990. Their analysis appears points to one major culprit: silica, a human lung carcinogen that makes it harder for people exposed to breathe.

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Silica dust comes off the rocks that typically surround layers of coal in the mines. It’s always been there, but the study authors hypothesize that, since the early 2000s, more miners have been exposed as newer technology has allowed them to access thinner layers of coal that feature more rock layers in between. Silica is 20 times more toxic than coal dust, said author Robert Cohen, a professor of environmental and occupational health sciences at the University of Illinois at Chicago School of Public Health.

“That probably means that there has to be much more attention to the control of the exposures to silica in our nation’s mines,” Cohen told Earther.

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You see, the lung specimens the team examined showed that the progressive massive fibrosis–the most severe state of black lung, better known as PMF—that former coal workers suffer from has changed since 1990. Silicotic PMF, which is caused by silica exposure, made up 40 percent of the researchers’ 102 cases of PMF after 1990. Of the 274 PMF cases pre-1990, only 24 percent were silicotic. This may also help explain why miners from more recent generations are dying at higher rates compared to older generations, too.

“[This discovery] reflects modern disease, modern technology, modern exposures,” Cohen said. “It doesn’t mean that [younger miners are] more susceptible than older miners, but it means that this is more recent.”

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More importantly, it’s giving us ammo to help protect these workers. Rates of PMF fell as the federal government passed regulations on dust in the workplace in the 1970s. However, there’s been an uptick since the 1990s, and scientists like Cohen are finally finding some answers.

The studies are based on individuals who voluntarily submitted the data, so there’s potential for bias in who opted to take part. And there’s always a chance death certificates include wrong or imperfect coding, but Cohen doesn’t expect that these limitations changed any of the overall conclusions.

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There’s still a lot of questions to answer, but these results are startling—especially as President Donald Trump promises to revive a dying industry responsible for killing thousands of workers over the last few decades.