( April 16, 2025, 4:27 PM EDT) -- ST. LOUIS — The American Thoracic Society (ATS) and United Mine Workers of America International Union, along with United Steel, moved separately in the Eighth Circuit U.S. Court of Appeals for leave to intervene in a dispute over the implementation of the “silica rule” issued by the Mine Safety and Health Administration (MSHA) related to miners’ exposure to crystalline silica. The ATS argues that the rule should be enforced “as soon as possible,” and the United Mine Workers parties say they seek to protect the silica rule for “the benefit of their members and the nation’s miners generally.”...