Ammonium perchlorate shows up in hundreds of military munitions, from signal smoke (orange, green, violet and beyond) to hand grenades and anti-tank rockets, and on military bases from California to Connecticut. According to an analysis of government data by the nonprofit Environmental Working Group, perchlorate has contaminated soil and water in 43 states, and drinking water in 22 states.

Now, some watchdog groups say the Defense Department is trying to avoid responsibility for its perchlorate problem. They point to a provision within the Pentagon's "Readiness and Range Preservation Initiative" that would exempt the military - along with private contractors like Kerr-McGee, Boeing, General Dynamics and Lockheed Martin - from perchlorate cleanup and financial liability (HCN, 3/31/03: While the nation goes to war, the Pentagon lobs bombs at environmental laws).

According to the Environmental Protection Agency, cleanup of just one perchlorate-contaminated site in Sacramento County, Calif., will take 240 years; the first of its six phases will cost $111 million. "You multiply that by hundreds of sites, and the cleanup liability is enormous," says Bill Martin of the Environmental Working Group's Oakland office. "It's not surprising (the Defense Department) is trying to exempt themselves from cleanup."

But Western senators - whose states could be stuck with billions of dollars in cleanup costs - are fighting the Pentagon's proposal. In California, where the state has already found perchlorate in 292 groundwater wells, Democratic Senators Dianne Feinstein and Barbara Boxer have joined forces with Sen. Harry Reid, D-Nev., to demand that the Defense Department take a more "aggressive and positive" role in cleaning up perchlorate at and around its bases.

The Pentagon released its new draft of the proposal in mid-March, and it will go to the floor of the U.S. House of Representatives on May 15.