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Human health risk assessment of air emissions from development of unconventional natural gas resources


Human health risk assessment of air emissions from development of unconventional natural gas resources

Science of the Total Environment
21 Mar 2012 [Epub ahead of print]
Lisa M. McKenzie, Roxana Z. Witter, Lee S. Newman, John L. Adgate

Technological advances (e.g. directional drilling, hydraulic fracturing), have led to increases in unconventional natural gas development (NGD), raising questions about health impacts.

We estimated health risks for exposures to air emissions from a NGD project in Garfield County, Colorado with the objective of supporting risk prevention recommendations in a health impact assessment (HIA).

We used EPA guidance to estimate chronic and subchronic non-cancer hazard indices and cancer risks from exposure to hydrocarbons for two populations: (1) residents living >½mile from wells and (2) residents living ≤½mile from wells.

Residents living ≤½mile from wells are at greater risk for health effects from NGD than are residents living >½mile from wells. Subchronic exposures to air pollutants during well completion activities present the greatest potential for health effects. The subchronic non-cancer hazard index (HI) of 5 for residents ≤½mile from wells was driven primarily by exposure to trimethylbenzenes, xylenes, and aliphatic hydrocarbons. Chronic HIs were 1 and 0.4. for residents ≤½mile from wells and >½mile from wells, respectively. Cumulative cancer risks were 10 in a million and 6 in a million for residents living ≤½mile and >½mile from wells, respectively, with benzene as the major contributor to the risk.

Risk assessment can be used in HIAs to direct health risk prevention strategies. Risk management approaches should focus on reducing exposures to emissions during well completions. These preliminary results indicate that health effects resulting from air emissions during unconventional NGD warrant further study. Prospective studies should focus on health effects associated with air pollution.
Additional Reading:
Roxana Witter, MD, MSPH et al. (2008). Potential Exposure-Related Human Health Effects of Oil and Gas Development: A White Paper Download (missing link)

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