How Environmentalists Lost the Battle Over TCE

"It is a World Trade Center in slow motion," said Boston University epidemiologist David Ozonoff, a TCE expert. "You would never notice it."

Senior officials in the Defense Department say much remains unknown about TCE.

"We are all forgetting the facts on the table," said Alex A. Beehler, the Pentagon's top environmental official. "Meanwhile, we have done everything we can to curtail use of TCE."

But in the last four years, the Pentagon, with help from the Energy Department and NASA, derailed tough EPA action on such water contaminants as the rocket fuel ingredient perchlorate. In response, state regulators in California and elsewhere have moved to impose their own rules.

The stakes are even higher with TCE. 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, as well as the shuttered El Toro Marine Corps base in Orange County.

Developed by chemists in the late 19th century, TCE was widely used to degrease metal parts and then dumped into nearby disposal pits at industrial plants and military bases, where it seeped into aquifers.

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. Limiting such exposures, even at current federal regulatory levels, requires elaborate treatment facilities that cost billions of dollars annually. In addition, some cities, notably Los Angeles, have high ambient levels of TCE in the air.

An internal Air Force report issued in 2003 warned that the Pentagon alone has 1,400 sites contaminated with TCE.

Among those, at least 46 have involved large-scale contamination or significant exposure to humans at military bases, according to a list compiled by the Natural Resources New Service, an environmental group based in Washington.