"By placing politics before science, the Bush administration is putting the public in harm's way," Sen. Barbara Boxer (D., Calif.) said at a hearing into the EPA's toxic-chemical programs.

A report by the Government Accountability Office said that White House demand for broad interagency involvement in the EPA's toxic-chemical risk assessments was undermining the agency's ability to make timely, science-based conclusions on the cancer risks and other health impacts of many chemicals.

John Stephenson, the GAO's director of natural-resource programs, told the Senate Environment Committee that the White House Office of Management and Budget was closely involved in the chemical assessments and "actually dictating which assessments that the EPA can undertake."

At issue is the EPA's screening of chemicals used in everything from household products to rocket fuel to determine whether they pose serious risk of cancer or other illnesses.

Jane Lee, a spokeswoman for the OMB, said the congressional report "mischaracterizes the interagency review process" that is used in the development of the chemical assessments.

"EPA works collaboratively with OMB and other agencies to achieve resolution of issues," Lee said in a statement responding to the Senate hearing. "Only EPA has the authority to finalize an EPA assessment and the authority to send the draft for external peer review."

EPA Assistant Administrator James Guilliford said that outside agency and White House involvement in the chemical reviews was beneficial and that the agency had "a process that ultimately results in a science-based result."

"Ultimately at the end of the day, it's EPA's decision," said Guilliford, who oversees the EPA's pesticide and toxic-substance programs.

The administration's decision to give the Pentagon and other agencies an early role in the process adds to years of delay in acting on harmful chemicals and jeopardizes the program's credibility, the GAO wrote.