Updated

With a top government scientist calling for more research into the possible health effects of hydraulic fracturing, Colorado has enacted the toughest fracking disclosure rules in the country.

Hydraulic fracturing, or fracking, is a technique developed to enable the extraction of vast, untapped amounts of oil and natural gas trapped inside underground shale rock formations.

"The shale plays are very important for the United States and for the world," according to Colorado School of Mines Professor Dr. William Fleckenstein. "There is such a large, vast amount of hydrocarbons that are now available for development. That's probably one of the most important energy developments that's occurred essentially since the first oil well was drilled."

Fracking involves drilling straight down, past aquifers, anywhere from 3,000 to 12,000 feet and from there drilling horizontally along shale formations anywhere from 1,000 to 10,000 feet.

Fleckenstein explains that several of these horizontal shafts can be drilled in any direction from a single vertical well. "It allows you to develop a square mile only from one surface location so that you don't have the disruption that's going to occur with a bunch of different vertical wells."

Liquid is pumped along each horizontal shaft at high pressure causing fractures in the shale through which oil or gas can be extracted. There is no denying the value of fracking: 90 percent of the wells in operation today have been fracked. But public fears about exactly what energy companies are pumping into the ground and whether it might affect the environment abound.

"Actually, these are primarily what they call water fracks," Fleckenstein says. "Which are what the name implies: mainly water. So 99 1/2 percent of the material that's going down in these wells is either water or a solid propping agent like a sand. You might have a half of a percent of other chemicals, most of which are very commonly found in a lot of households."

Companies have been reluctant to reveal exactly what those chemicals they are for fear that competitors will copy what they consider proprietary secrets.

Under an agreement brokered by Colorado Gov. John Hickenlooper energy companies have agreed to disclose to the public at least the chemical family of each chemical they use. The disclosure must be made within two months on an independent internet database: FracFocus.org. Anyone can go to the site to look up chemicals used in the fracking of virtually any well in the state of Colorado. Representatives from both the energy industry and environmental groups who were involved in the negotiations credit Hickenlooper, a Democrat and businessman who once worked as a geologist in the energy industry, with bringing the two sides together.

"It's his vision that resulted in a sometimes bumpy, sometimes not so smooth, sometimes antagonistic process that resulted in what I can call one of the best rules in the country when it comes to disclosure of fracking materials," noted Dan Grossman, Rocky Mountain Regional Director for the Environmental Defense Fund.

"As Governor Hickenlooper explained trade secrets are are a vital part of our legal process," added Dave Neslin, Director of the Colorado Oil and Gas Conservation Commission. "They are protected by federal and state law and they encourage innovation and investment including innovation in greener fracturing fluids.

"I think we've reached the fairest rules on the transparency of frack fluids of any state in the country," Hickenlooper said. "I think this will likely become a national model that if other states don't copy it, they will certainly use it as a touch point."

So far 11 states have, or are working on, their own regulations regarding the disclosure of fracking fluids. But concerns remain. Dr. Christopher Portier of the Centers for Disease Control maintains that not enough is known about the possible effects of fracking fluid ingredients and that further studies are needed to determine if they pose any threat to human health.