Study examines risk of living near natural gas wells - Business, Government Legal News from throughout WV

Study examines risk of living near natural gas wells

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A new study from Colorado estimates health risks for exposure to air emissions near natural gas wells and offers some recommendations for reducing some of those risks.

The study suggests efforts to reduce exposures to emissions during the well completion process, including cancer risks. Exposure to benzene, the authors of the study found, accounted for a cumulative cancer risk of 10 in a million for those living less than one-half mile away from gas wells.

"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 Lisa McKenzie, lead author of the study and research associate at the Colorado School of Public Health.

Cancer isn't the only concern. Chemicals such as trimethylbenzenes, aliaphatic hydrocarbons and xylenes also are emitted. Those chemicals could cause eye irritation, headaches, sore throat and difficulty breathing.

Sources of the emissions include direct and fugitive emissions from the natural gas, as well as diesel engines, produced water and other on-site materials, the study states.

Emissions peaked at the site studied during well completion, when drillers are readying the well for production. This means a higher hazard index, but for mostly non-chronic conditions.

"Our results show that the non-cancer (hazard index) from air emissions due to natural development is greater for residents living closer to wells," the report states. "Our greatest hazard index corresponds to the relatively short-term (i.e. subchronic), but high emission, well completion period."

Specifically, the study links the emissions to the flowback operations, which is when hydraulic fracturing fluid resurfaces. The fluid is pumped into the ground to fracture shale formations and release the natural gas below.

According to the study, the area is mostly rural, with agricultural being the only other dominating industry. Despite this, the levels of benzene and other pollutants in the are were higher than 27 of 37 air toxic monitoring sites including urban centers such as Tulsa, Elizabeth, N.J., and Dearborn, Mich.       

Some of the same chemicals found near natural gas sites, the authors write, have been linked to acute childhood leukemia, multiple myeloma and eye irritation and headaches.

"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."

The highest hydrocarbon levels, predictably, were often found downwind of facilities.

Much of the environmental criticism of the natural gas industry has focused on water contamination issues. The Colorado School of Public Health looked at air emissions, which the authors conclude warrants even further study.

The study focused on three years of monitoring data from Colorado gas well in Garfield County. Researchers used EPA guidance to estimate chronic and subchronic risks from hydrocarbon exposure for two groups — residents within a half-mile of a well, and residents greater than a half-mile from the well.

The EPA's hazard index is a sum of hazard quotients in an area, the ratio of potential exposure and the level which no adverse affect is expected.

McKenzie said EPA standards used in the study may overestimate the risk in some cases, but due to data not available on chemicals emitted during the well development process, the risks could be underestimated as well.

According to the study, data may have been better if different distances could have been measured. Other temporal and spatial restrictions also somewhat limited the scope of the story.

"However, there is more certainty in the comparison of the risks between the populations and in the comparison of subchronic to chronic exposures because the limitations and uncertainties similarly affected the risk estimates," the study states.

The study, "Human Health Risk Assessment of Air Emissions from Development of Unconventional Natural Gas Resources" was accepted for publication in March by Elsevier Science Ireland Ltd. The researcher claims no competing financial interest with the story.


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