A crew worked on a gas drilling rig at a well site for shale-based natural gas in Zelienople, Pa.
A crew worked on a gas drilling rig at a well site for shale-based natural gas in Zelienople, Pa. File photo by Keith Srakocic The Associated Press
A crew worked on a gas drilling rig at a well site for shale-based natural gas in Zelienople, Pa. File photo by Keith Srakocic The Associated Press

U.S. tightens rules for chemical disclosure in fracking

March 20, 2015 7:08 PM