In 1950, the US Public Health service began a comprehensive study of uranium miners, leading to the first publication of a statistical correlation between cancer and uranium mining, released in 1962. The federal government eventually regulated the standard amount of radon in mines, setting the level at 0.3 WL on January 1, 1969.
Out of 69 present and former uranium milling sites in 12 states, 24 have been abandoned, and are the responsibility of the US Department of Energy.  Accidental releases from uranium mills include the 1979 Church Rock uranium mill spill in New Mexico, called the largest accident of nuclear-related waste in US history, and the 1986 Sequoyah Corporation Fuels Release in Oklahoma.
In 1990, Congress passed the Radiation Exposure Compensation Act (RECA), granting reparations for those affected by mining, with amendments passed in 2000 to address criticisms with the original act.