WASHINGTON -- A report by congressional investigators said the Bush administration is undermining the Environmental Protection Agency's ability to determine health dangers of toxic chemicals by letting nonscientists have a bigger say.

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

The Government Accountability Office report concluded that the decision to give the Defense Department and other agencies an early role in the process adds to years of delay in acting on harmful chemicals. It also says the decision jeopardizes the program's credibility.

GAO investigators said extensive involvement by EPA managers, White House budget officials and other agencies has eroded the independence of EPA scientists charged with determining the health risks posed by chemicals.