Fracking, or hydrofracking, which is short for hydraulic fracturing, is a common but controversial practice among companies that drill underground for oil and natural gas. In fracking, drillers inject millions of gallons of water, sand, salts and chemicals-all too often toxic chemicals and human carcinogens such as benzene-into shale deposits or other sub-surface rock formations at extremely high pressure, to fracture the rock and extract the raw fuel.
The purpose of fracking is to create fissures in underground rock formations, thereby increasing the flow of oil or natural gas and making it easier for workers to extract those fossil fuels.
How Common Is Fracking?
The fracking process is used to boost production at 90 percent of all oil and gas wells in the United States, according to the Interstate Oil and Gas Compact Commission, and fracking is increasingly common in other countries as well.
Although fracking most often occurs when a well is new, companies fracture many wells repeatedly in an effort to extract as much valuable oil or natural gas as possible and to maximize the return on their investment in a profitable site.
The Dangers of Fracking
Fracking poses serious dangers to both human health and the environment. The three biggest problems with fracking are:
- Fracking leaves behind a toxic sludge (called drill cuttings) that companies and communities must find some way to manage. Safely disposing of the sludge created by fracking is an ongoing challenge.
- Somewhere between 20 percent and 40 percent of the toxic chemicals used in the fracking process remain stranded underground where they can, and often do, contaminate drinking water, soil and other parts of the environment that support plant, animal and human life.
- Methane from fracture wells can leak into groundwater, creating a serious risk of explosion and contaminating drinking water supplies so severely that some homeowners have been able to set fire to the mixture of water and gas coming out of their faucets.
Methane also can cause asphyxiation. There isn't much research on the health effects of drinking water contaminated by methane, however, and the EPA doesn't regulate methane as a contaminant in public water systems.
According to the U.S. Environmental Protection Agency (EPA), a least nine different chemicals commonly used in fracking are injected into oil and gas wells at concentrations that pose a threat to human health.
Fracking also poses other hazards, according to the Natural Resources Defense Council, which warns that besides contaminating drinking water with toxic and carcinogenic chemicals, fracking could trigger earthquakes, poison livestock, and overburden wastewater systems.
Why Concerns About Fracking are Increasing
Americans get half their drinking water from underground sources. Accelerated gas drilling and hydrofracking in recent years has fueled public concern about well-water contamination by methane, fracking fluids and "produced water," the wastewater extracted from wells after the shale has been fractured.
So it's no wonder people are increasingly concerned about the risks of fracking, which is becoming more widespread as gas exploration and drilling expands.
Gas extracted from shale currently accounts in 2011 for about 15 percent of natural gas produced in the United States. The Energy Information Administration estimates it will make up almost half of the nation's natural-gas production by 2035.
In 2005, President George W. Bush exempted oil and gas companies from federal regulations designed to protect U.S. drinking water, and most state oil and gas regulatory agencies don't require companies to report the volumes or names of the chemicals they use in the fracking process, chemicals such as benzene, chloride, toluene and sulfates.
The result, according to the nonprofit Oil and Gas Accountability Project, is that one of the nation's dirtiest industries is also one of its least regulated, and enjoys an exclusive right to "inject toxic fluids directly into good quality groundwater without oversight."
Congressional Study Confirms Fracking Uses Hazardous Chemicals
In 2011, congressional Democrats released the results of an investigation showing that oil and gas companies injected hundreds of millions of gallons of hazardous or carcinogenic chemicals into wells in more than 13 states from 2005 to 2009. The investigation was initiated by the House Energy and Commerce Committee in 2010, when the Democrats controlled the U.S. House of Representatives.
The report also faulted companies for secrecy and for sometimes “injecting fluids containing chemicals that they themselves cannot identify.”
The investigation also found that 14 of the most active hydraulic fracturing companies in the United States used 866 million gallons of hydraulic fracturing products, not including the water that makes up the bulk of all fracking fluid. More than 650 of the products contained chemicals that are known or possible human carcinogens, which are regulated under the Safe Drinking Water Act or listed as hazardous air pollutants, according to the report.
Scientists Find Methane in Drinking Water
A peer-reviewed study conducted by scientists at Duke University and published in the Proceedings of the National Academy of Sciences in May 2011 linked natural gas drilling and hydraulic fracturing to a pattern of drinking-water contamination so severe that faucets in some areas can be lit on fire.
After testing 68 private groundwater wells across five counties in northeastern Pennsylvania and southern New York, the Duke University researchers found that the amount of flammable methane gas in wells used for drinking water increased to dangerous levels when those water sources were close to natural-gas wells.
They also found that the type of gas detected at high levels in the water was the same type of gas that energy companies were extracting from shale and rock deposits thousands of feet underground. The strong implication is that natural gas may be seeping through either natural or man-made faults or fractures, or leaking from cracks in the gas wells themselves.
“We found measurable amounts of methane in 85 percent of the samples, but levels were 17 times higher on average in wells located within a kilometer of active hydrofracking sites,” said Stephen Osborn, postdoctoral research associate at Duke's Nicholas School of the Environment.
Water wells farther from the gas wells contained lower levels of methane and had a different isotopic fingerprint.
The Duke study found no evidence of contamination from chemicals in the fracking fluids that are injected into gas wells to help break up shale deposits, or from produced water.