"President Barack Obama's top environmental adviser urged the natural gas industry on Tuesday to disclose the chemicals it uses in drilling, warning that the development of massive U.S. shale gas reserves could be held back otherwise.

Joseph Aldy, special assistant to the president for energy and the environment, said concerns about water contamination from drilling chemicals could lead to states requiring disclosure and that could deter additional investment. ...

Some energy companies decline to publish lists of toxic chemicals used in hydraulic fracturing, a technique used to extract natural gas from shale beds far underground.

Companies have been under pressure from critics of fracturing and from some lawmakers, who say the technique is damaging the water supplies of people who live near gas rigs.

Aldy said it is unclear whether fracturing chemicals are fouling groundwater but acknowledged the industry is under pressure from those who say the process leads to contamination with chemicals that can cause a range of illnesses."

Jon Hurdle reports for Reuters March 11, 2010. [2]