"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," said Doctor Lisa McKenzie of the Colorado School of Public Health.
The report, based on three years of monitoring, found a number of potentially toxic petroleum hydrocarbons in the air near the wells including benzene, ethylbenzene, toluene and xylene. Benzene has been identified by the Environmental Protection Agency as a known carcinogen. Other chemicals included heptane, octane and diethylbenzene but information on their toxicity is limited.
"Our results show that the non-cancer health impacts from air emissions due to natural gas development is greater for residents living closer to wells," the report said. "The greatest health impact corresponds to the relatively short-term, but high emission, well completion period."
That is due to exposure to trimethylbenzenes, aliaphatic hydrocarbons, and xylenes, all of which have neurological and/or respiratory effects, the study said. Those effects could include eye irritation, headaches, sore throat and difficulty breathing.
"We also calculated higher cancer risks for residents living nearer to the wells as compared to those residing further away," researchers say. "Benzene is the major contributor to lifetime excess cancer risk from both scenarios."
The report, which looked at those living about a half-mile from the wells, comes in response to the rapid expansion of natural gas development in rural Garfield County, in western Colorado.
Typically, wells are developed in stages that include drilling followed by hydraulic fracturing, the high powered injection of water and chemicals into the drilled area to release the gas. After that, there is flow back or the return of fracking and geologic fluids, hydrocarbons and natural gas to the surface. The gas is then collected and sold.
McKenzie analysed ambient air sample data collected from monitoring stations by the Garfield County Department of Public Health and Olsson Associates Inc. She used standard EPA methodology to estimate non-cancer health impacts and excess lifetime cancer risks for hydrocarbon exposure.
"However, there was not data available on all the chemicals emitted during the well development process," she said. "If there had been, then it is entirely possible the risks would have been underestimated."
MEDICA.de; Source: Colorado School of Public Health