Oil and gas companies injected hundreds of millions of gallons of hazardous or carcinogenic chemicals into wells in more than 13 states from 2005 to 2009, according to an investigation by Congressional Democrats.

A federal proposal laying out new standards for a controversial natural-gas drilling practice called hydraulic fracturing likely won’t be issued until after the 2012 elections...the timing of the standards would take that hot-button issue off the table.

European energy companies are scrambling to secure licenses to roll out extraction projects this side of the Atlantic. ...Experts have increasingly expressed concern that the chemicals used in fracking may pose a threat underground or when waste fluids are transported or spilled.