Millions of gallons of potentially hazardous chemicals and known carcinogens were injected into wells by leading oil and gas service companies from 2005 to 2009, a report by three House Democrats said Saturday.
The report said 29 of the chemicals injected were known or suspected human carcinogens. They either were regulated under the Safe Drinking Water Act as risks to human health or listed as hazardous air pollutants under the Clean Air Act.
Methanol was the most widely used chemical. The substance is a hazardous air pollutant and is on the candidate list for potential regulation under the Safe Drinking Water Act.
The report was issued by Reps. Henry Waxman of California, Edward Markey of Massachusetts and Diana DeGette of Colorado.
The chemicals are injected during hydraulic fracturing, a process used in combination with horizontal drilling to allow access to natural gas reserves previously considered uneconomical.
The growing use of hydraulic fracturing has allowed natural gas production in the United States to reach levels not achieved since the early 1970s.
However, the process requires large quantities of water and fluids, injected underground at high volumes and pressure. The composition of these fluids ranges from a simple mixture of water and sand to more complex mixtures with chemical additives.
The report said that from 2005 to 2009, the following states had at least 100,000 gallons of hydraulic fracturing fluids containing a carcinogen injected underground: Texas, Colorado, Oklahoma, Louisiana, Wyoming, North Dakota, New Mexico, Montana and Utah.
States with 100,000 gallons or more of fluids containing a regulated chemical under the Safe Drinking Water Act were: Texas, New Mexico, Colorado, Oklahoma, Mississippi and North Dakota.
The report said many chemical components were listed as "proprietary" or "trade secret."
"Hydraulic fracturing has opened access to vast domestic reserves of natural gas that could provide an important stepping stone to a clean energy future," the report said.
"Yet, questions about the safety of hydraulic fracturing persist, which are compounded by the secrecy surrounding the chemicals used in hydraulic fracturing fluids. This analysis is the most comprehensive national assessment to date of the types and volumes of chemical used in the hydraulic fracturing process."
Online: House Energy and Commerce Democratic site