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Air Pollutants Found Near Hydraulic Fracturing Gas Wells

Marcellus shale gas well in West Virginia (dep.wv.gov)
Marcellus shale gas well in West Virginia (dep.wv.gov)

Research conducted at the University of Colorado School of Public Health in Denver indicates the natural gas drilling practice known as hydraulic fracturing or fracking may be causing the release of toxic chemicals in the air near drilling sites. The findings of Lisa McKenzie, a Colorado public health research associate, and colleagues have been accepted for publication by the journal Science of the Total Environment.

McKenzie and colleagues carried out their research in Garfield County, Colorado after the county asked the School of Public Health to help assess the impact of shale gas drilling near the community of Battlefield Mesa, Colorado, about 200 miles west of Denver. The team analyzed ambient air samples taken for three years by Garfield County and the engineering company Olsson Associates Inc. within a half-mile of the proposed wells. The researchers used standard EPA methods for estimating non-cancer health impacts and excess lifetime cancer risks for hydrocarbon exposure.

The report of the research found several toxic petroleum hydrocarbons in the air near the wells including benzene, ethylbenzene, toluene, and xylene. Benzene, in particular, has been identified by the Environmental Protection Agency as a known carcinogen, for all routes of exposure, including inhalation. The researchers found higher cancer risks for residents living nearer to the wells compared to those residing further away, with benzene being the major contributor to lifetime excess cancer risk.

McKenzie also found higher risks of non-cancer health impacts, mainly for residents living closer to wells, particularly during the short-term, but high-emission drilling period early in the fracturing process. The non-cancer risks appear related to the use of trimethylbenzenes, aliphatic hydrocarbons (those without benzene, such as methane and alkanes), and xylenes, all of which have neurological and/or respiratory effects. Symptoms of these effects include eye irritation, headaches, sore throat, and difficulty breathing.

“Our data show that it is important to include air pollution in the national dialogue on natural gas development that has focused largely on water exposures to hydraulic fracturing,” says McKenzie.

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