Study links black lung disease to increases in silica exposure

black lung disease

High rates of severe coal worker pneumoconiosis, which is more commonly known as black lung disease, has been attributed to an increase in silica exposure in a study published by occupational health experts at the university of Illinois Chicago.

Prior to 2005, incidents of black lung disease had been on the decline ever since modern coal dust controls were implemented within mines.

The study is the first to compare the pathology and mineralogy of pneumoconiosis across generations, and the first to explain why the most severe form of black lung disease is occurring more frequently among young coal workers across the United States.

Dr Robert Cohen, Clinical Professor of Environmental and Occupational Health Sciences and Director of the Mining Education and Research Centre at UIC, explained the reasoning behind why the study was undertaken.

“We have known that silica is highly toxic, and exposure contributes to coal workers’ pneumoconiosis, but we have not known why coal workers were suddenly experiencing more disease and more severe forms of it,” Cohen said.

“Regulations have remained in place, minerals in the Earth have not changed, and there is no evidence suggesting people have become more vulnerable to coal dust, so the rise in cases among young workers that started in the late 90s was baffling.”

Researchers found a clear link between the factors of silica exposure and severe cases of black lung diseases in contemporary miners;

  • Contemporary miners had significantly higher rates of silica-type disease compared to their historical counterparts,
  • Mineral dust alveolar proteinosis was more common in contemporary miners,
  • The percentage and concentration of silica particles were significantly greater in contemporary miners; and
  • The concentration of silica particles was significantly greater (more than 50 per cent) when silica‐type severe black lung, mineral dust alveolar proteinosis, silicotic nodules or immature silicotic nodules were present.

From these finding, the mine safety and health administration has requested to change the standard of silica exposure rules, from 100 micrograms per cubic centimetre to the number which is set by the occupational safety and health administration, of 50 micrograms per cubic centimetre.

“These findings provide the first direct evidence that silica is a causative agent behind the increasing incidence of progressive massive fibrosis — severe pneumoconiosis,” said Cohen.

“This is critical information that can be used to determine health-protective permissible exposure limits for coal miners.”

These findings were published in the Annals of the American Thoracic Society, the paper titled: ‘Pathology and Mineralogy Demonstrate Respirable Crystalline Silica is a Major Cause of Severe Pneumoconiosis in US Coal Miners.