Another crack in the “fracking is safe” story for the industry to address.

You know that fracking thing? For the uninitiated, hydraulic fracturing (a.k.a. fracking) is the technique of injecting water, sand and chemicals at high pressures into shale and other tight rock formations to release the fuel trapped inside. Combined with horizontal drilling, fracking has allowed us to access huge amounts of heretofore unrecoverable natural gas.

What a bonanza: a new and sizable source of natural gas. And, at first blush, a fuel that’s good for the environment: natural gas is the cleanest of the fossil fuels and has already begun displacing coal, the dirtiest fossil fuel, in U.S. power plants.

But alas, as with most too-good-to-be-true things, fracking’s