(CNN) -- The Environmental Protection Agency is formally requesting the chemical composition of fluids used in hydraulic fracturing during natural gas extraction, senior agency officials said.
In the first-of-its-kind request from the agency, the EPA sent letters Tuesday to nine leading national and regional hydraulic fracturing service providers: Halliburton, BJ Services, Complete Production Services, Key Energy Services, Patterson-UTI, PRC Inc., Schlumberger, Superior Well Services and Weatherford.
"Natural gas is an important part of our nation's energy future, and it's critical that the extraction of this valuable natural resource does not come at the expense of safe water and healthy communities," EPA Administrator Lisa P. Jackson said in a statement. "EPA will do everything in its power, as it is obligated to do, to protect the health of the American people and will respond to demonstrated threats while the study is underway."
The companies have seven days to say if they will cooperate, and then 30 days to produce the list of the fracturing fluid chemicals used and their percentages, senior agency officials said.
If they do not comply, the EPA will "use authorities to require the information needed to carry out its study," senior agency officials said.
Halliburton had yet to receive the formal request Tuesday from the EPA regarding additional information on its hydraulic fracturing fluids, but will "fully cooperate with their request," Halliburton spokeswoman Teresa Wong said in a statement.
"Halliburton supports and continues to comply with state, local and federal requirements promoting the forthright disclosure of the chemical additives that typically comprise less than one-half of one percent of our hydraulic fracturing solutions," Wong said. "We view this both as a means of enhancing public safety, and as a way to engage the public in a straightforward manner."
Natural gas extraction is at the forefront of one of the biggest energy developments this century. And the 2005 Energy Act signed during the Bush administration did not subject fracturing to oversight under the Clean Water Act.
The Marcellus Shale, one of the largest natural gas deposits in the nation, is beneath parts of Pennsylvania, New York, West Virginia and Ohio. The natural gas reserve is attracting a flurry of gas companies wanting to drill.
Accessing the natural gas involves the controversial process of hydraulic fracturing, or "fracking." Fracturing requires drillers to pump large amounts of water mixed with sand and chemicals into the shale formation under high pressure to depths 8,000 feet or greater, or even wells less than 1,000 feet, according to the EPA. This process fractures the shale around the well, which allows the natural gas to flow freely, according to the Pennsylvania Department of Environmental Protection.
With the expansion of fracturing, there are increased concerns about its potential effects on the underground water table, public health and the environment. The concerns have prompted an EPA study of the potential problems with fracturing and public hearings to help decide how to conduct the study. The chemical data collected will be used in the study.
In 2009, Congress directed the agency to conduct a study to determine whether hydraulic fracturing has an effect on drinking water and the public health of Americans living near hydraulic fracturing wells.
Meanwhile, on August 31, the EPA said it found benzene and methane in wells and in groundwater in Pavillion, Wyoming, after a drinking water contamination investigation. No conclusions were made about the sources of chemical compounds found in drinking water wells, including hydraulic fracturing.
The U.S. Department of Health and Human Services' Agency for Toxic Substances recommended that affected well owners use alternate sources of water for drinking and cooking, agency officials said.
In Pavillion, the EPA is working with government partners and EnCana, the primary natural gas drilling company in the region, to provide affected residents with water and to address potential sources of the contamination, agency officials said.
The EPA will hold its final public hearing on hydraulic fracturing at the Broome County Forum Theater in Binghamton, New York, on Monday and Wednesday. In July, public hearings were held in Fort Worth, Texas; Denver, Colorado; and Canonsburg, Pennsylvania, to help determine how the EPA will conduct the study.
The agency plans to begin the study in January 2011 and release initial study results by late 2012.