What happened with TCE is a stark illustration of a power shift that has badly damaged the EPA's ability to carry out one of its essential missions: assessing the health risks of toxic chemicals.

Half a dozen state, federal and international agencies classify TCE as a probable carcinogen. [...] California EPA regulators consider TCE a known carcinogen and issued their own 1999 risk assessment that reached the same conclusion as federal EPA regulators: TCE was far more toxic than previous scientific studies indicated.

TCE is the most widespread water contaminant in the nation. Huge swaths of California, New York, Texas and Florida, among other states, lie over TCE plumes. The solvent has spread under much of the San Gabriel and San Fernando valleys.....

The public is exposed to TCE in several ways, including drinking or showering in contaminated water and breathing air in homes where TCE vapors have intruded from the soil. [...] In addition, some cities, notably Los Angeles, have high ambient levels of TCE in the air.

If the EPA's 2001 draft risk assessment was correct, then possibly thousands of the nation's birth defects and cancers are due in part to TCE exposure, according to several academic experts.

The agency's authority and its scientific stature have been eroded under a withering attack on its technical staff by the military and its contractors.

[C]ritics say the defense establishment has manufactured unwarranted scientific doubt, used its powerful role in the executive branch to cause delays and forced a reduction in the margins of protection....

The military says it is only striving to make smart decisions based on sound science and accuses the EPA of being unduly influenced by left-leaning scientists.

A few months after the 2001 draft risk assessment came out, an Air Force rebuttal charged that the EPA had "misrepresented" data from animal and human health studies.

It said "there is no convincing evidence" that some groups of people, like children and diabetics, are more susceptible to TCE, a key part of the EPA's report. And it said the EPA had failed to consider viewpoints from "scientists who believe that TCE does not represent a human cancer risk at levels reasonably expected in the environment."

But comments such as these are outside the scientific mainstream. Other federal agencies have also expressed grave concern about TCE and some experts say it is only a matter of time before the chemical is universally recognized as a known carcinogen.

"The evidence on TCE is overwhelming," said Dr. Gina Solomon, an environmental medicine expert at UC San Francisco and a scientist at the Natural Resources Defense Council. "We have 80 epidemiological studies and hundreds of toxicology studies. They are fairly consistent in finding cancer risks that cover a range of tumors. It is hard to make all that human health risk go away."

"If you go down two or three levels in EPA, you have an awful lot of people that came onboard during the Clinton administration, to be perfectly blunt about it, and have a different approach than I do at Defense," said [Raymond F. DuBois, former deputy undersecretary of Defense for installations and environment in the Bush administration]. "It doesn't mean I don't respect their opinions or judgments, but I have an obligation where our scientists question their scientists to bring it to the surface."

[T]he Bush administration leadership at the EPA ultimately sided with the military.

They had political capital. This is how they used it. Sure, it costs money to clean up TCE and control exposure levels. But they had tax breaks to hand out, and a war of choice to fight--and what's the point of stealing elections if you still have to listen to Clinton people?