New US data shows many more coal miners suffering from the most serious form of black lung disease than previously reported.
America's National Public Radio reported on Friday that its investigation shows 962 cases so far this decade.
It comes as a number of miners in Queensland have also been diagnosed with the deadly disease.
On Thursday, the National Institute for Occupational Safety and Health said that 60 current and former miners from the US state of Kentucky were diagnosed with progressive massive fibrosis, the most severe form of black lung, between January 2015 and last August.
"The current numbers are unprecedented by any historical standard," NIOSH epidemiologist Scott Laney said.
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In the last three years, 644 cases of complicated black lung were diagnosed in three communities in the state of Virginia.
That's six times the NIOSH national count in nearly half the time.
Laney and other black lung experts believe thinner coal seams in the area are probably to blame.
The thin seams that remain have coal embedded in rock containing quartz - producing mining dust with silica that's especially toxic in lung tissue.
"I think the percentage of black lung that we're seeing now here ... is unprecedented in any recorded data that I can find anywhere," said radiologist Brandon Crum at United Medical Group clinic in Kentucky.
"In this clinic we're roughly around 9 to 10 per cent complicated rate, which is around three times higher than even the highest reported numbers."
Crum told NPR he was alarmed also that some affected miners were in their 30s and 40s and had worked less than 20 years underground.
