In the wake of the BP Gulf oil disaster, U.S. Sen. Robert Casey of Pennsylvania and U.S. Rep. Diana DeGette of Colorado warned in the Philadelphia Inquirer that hydraulic fracturing posed a parallel onshore risk, urging federal disclosure of fracking chemicals under the Safe Drinking Water Act. Challenging exemptions advanced during Vice President Dick Cheney’s 2005 energy legislation, Casey and DeGette argued that energy companies should disclose the ingredients in fracking fluids—diesel fuel, benzene, methanol, and formaldehyde among them—while preserving proprietary formulas, countering industry claims that state regulation alone was sufficient.