One of the biggest changes in natural gas drilling in the last decade has been the use of hydraulic fracturing (or "fracking") to free gas from captured rock. The practice involves pumping huge amounts of water and a chemical cocktail downhole into rock sometimes two miles deep.

The practice is prevalent – and controversial. The key to the controversy is what’s in the soup the drilling companies are pumping underground. Drilling companies generally refuse to say. That means the public has no idea what toxins are in the stuff. And those toxins could eventually migrate into aquifers used for drinking water by millions.

In Wyoming, for example, EPA is concerned that "at least three water wells contain a chemical used" in fracking. And in Durango, an emergency room nurse suffered organ failure after treating a gas field worker covered in chemicals presumed to be fracking fluid. The gas company wouldn’t say what was in the goop covering the worker.

What do gas companies have to fear from disclosure of fracking fluid ingredients?

According to press reports, it’s the ’11 herbs and spices’ defense: "Industry officials argue … that the types of chemicals being used are trade secrets that can give them a production edge over competitors." For this, the public must be kept in the dark about potential poison being pumped who knows where.

But in the past few months, fractures in the gas industry’s front against transparency have appeared. Two gas executives called for dislosure at a conference in the fall.

And now, a company in Colorado has agreed to "disclose the components of both drilling and frac[k]ing fluids" (though not the volumes of those components), and will take steps "to assure that chemicals used in the fracturing process will be biodegradable, nontoxic neutral pH, residual free, non-corrosive, non-polluting and non-hazardous in the forms and concentrations being used." The company will also inject tracers into the fluids and monitor where the fluids go to determine whether fracking has impacts on the local watershed.

Which begs the question—if industry can come clean on what’s in fracking fluid here in Colorado, why can’t they do it everywhere? And if they can, shouldn’t they?