Opponents of hydraulic fracturing or 'fracking' hold placards during a rally in Lafayette Square, across from the White House, on September 25, 2013 in Washington, DC. The demonstrators say they have collected 250,000 signatures calling on the EPA to re-open investigations into alleged fracking related pollution cases in Pennsylvania, Texas and Wyoming. AFP PHOTO/Mandel NGAN        (Photo credit should read MANDEL NGAN/AFP/Getty Images)