Living near to active fracking sites could increase the risk of cancer as the process harmful chemicals into the air, a new study has found.
Researchers from Oregon State University (OSU) and the University of Cincinnati found that hydraulic fracturing, commonly known as fracking, releases polycyclic aromatic hydrocarbons (PAHs), which are linked to cancers and respiratory diseases.
The study found that moving just one mile away from active sites reduced the levels of the dangerous chemicals in the air by up to 30%.
Fracking has proved a contentious issue among environmentalists, who claim the process is detrimental to the environment and human health. However, the process has been touted by some as a solution to the world's energy crisis, with a recent study estimating it could unlock 140 billion barrels of oil worldwide, the equivalent of Russia's standing oil reserves.
Co-author Kim Anderson, an environmental chemist at OSU, said: "Air pollution from fracking operations may pose an under-recognised health hazard to people living near them."
The study was published in Environmental Science & Technology. The team took air samples from sites near active natural gas wells in Carroll County, Ohio. The area is rife with fracking sites, having more than one active well per square mile.
Aluminium boxes containing polyethylene ribbons, which absorb pollutants in a similar manner to living cells, were used to measure PAH levels in the air.
Even the lowest PAH levels detected - those collected from air samples more than a mile away from a well - were 10 times higher than sites with no natural gas wells.
The team calculated that the cancer risk posed to a person living or working close to the well and constantly exposed to the pollutant exceeded the US Environmental Protection Agency's safe risk levels.
Fracking involves injecting millions of gallons of water, sand and chemicals at extremely high pressures into horizontally-drilled wells as deep as 10,000 feet below ground level. The process causes the rock to fracture and release natural gas reserves.
The US Geological Survey has previously blamed fracking for causing earthquakes.Try Newsweek: Subscription offers