Changes

Environmental impact of hydraulic fracturing in the United States of shale include the potential contamination of ground water, risks to air quality, the potential migration of gases and hydraulic fracturing chemicals to the surface, the potential mishandling of waste, and the health effects of these, such as cancer.<ref name="house1">{{cite web |url=http://democrats.energycommerce.house.gov/sites/default/files/documents/Hydraulic%20Fracturing%20Report%204.18.11.pdf |publisher=Committee on Energy and Commerce U.S. House of Representatives |title=Chemicals Used in Hydraulic Fracturing |date=April 18, 2011}}</ref><ref name="HeatOnGas"/> Many cases of suspected groundwater contamination have been documented.<ref>{{cite web |url=http://switchboard.nrdc.org/blogs/amall/incidents_where_hydraulic_frac.html |publisher=U.S. NRDC |title=Incidents where hydraulic fracturing is a suspected cause of drinking water contamination |date=December 2011 |accessdate=23 February 2012}}</ref> With the explosive growth of natural gas wells in the US, researcher Valerie Brown predicted in 2007 that "public exposure to the many chemicals involved in energy development is expected to increase over the next few years, with uncertain consequences."<ref name="HeatOnGas">{{cite article|last=Brown |first=Valerie J. |title=Industry Issues: Putting the Heat on Gas |date=February 2007 |journal=Environmental Health Perspectives |publisher=US National Institute of Environmental Health Sciences |issue=115(2) |http=http://ehp03.niehs.nih.gov/article/browseIssue.action?issue=info:doi/10.1289/issue.ehp.v115.i02}}[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1817691/ .]</ref>