Black lung diagnoses have doubled in the last decade, and a new investigation blames a combination of factors, including operators who cheat the system and lax enforcement by regulators.

Experts have warned of the disease's resurgence since 1995.

But an investigation by National Public Radio (http://n.pr/MUBhbH), the Center for Public Integrity and the Charleston Gazette concludes that all the systems designed to protect coal miners have failed.

That includes federal lawmakers, who won't pass regulations to toughen 1969 standards for coal dust.

The reports say the number of advanced black lung cases has quadrupled since the 1980s in eastern Kentucky, southern West Virginia and southwestern Virginia.

Scott Laney of the National Institute for Occupational Safety and Health says it's a public health epidemic, with a disease that shouldn't be occurring.