"Responding to reports of environmental contamination in gas drilling areas across the country, the U.S. Environmental Protection Agency will conduct a nationwide scientific study to determine if the problems are caused by the practice of injecting chemicals and water underground to fracture the gas-bearing rock.

The study, announced Thursday but hinted at for months, will revisit research the agency published in 2004, which concluded that the process of hydraulic fracturing did not pose a threat to drinking water. The 2004 report has been widely criticized, in part because the agency didn't conduct any water tests in reaching that conclusion."

Abrahm Lustgarten reports for ProPublica March 18, 2010. [2]