The U.S. Department of Defense hopes to ship over 3,000 tons of materials containing polychlorinated biphenyls stored at military bases in Japan to the United States for recycling or disposal, officials at the U.S. Embassy in Tokyo said Wednesday.

The department will release an environmental assessment of the shipping procedure finding "no significant impact," but recommending that the materials be transported to the U.S. instead of stored indefinitely, the U.S. officials said.

The decision is pending the results of a public comment period. If approved, the assessment would allow the import of U.S.-manufactured PCBs, which account for just over a third of those on U.S. military facilities in Japan, the officials said. The import of Japanese manufactured PCBs would require the U.S. Environment Protection Agency to exempt these materials from a ban on such imports.

The move is an effort to overcome a glut of PCB-containing materials stored at U.S. bases in Japan since a U.S. court ruled against the import of PCBs in 1997.

Contaminated materials are stored at at least 15 sites around Japan, but the bulk, or 357 tons, is located at the Sagami Depot administered by Camp Zama in Sagamihara, Kanagawa Prefecture. The majority of PCB-containing equipment, 1,234 tons, is still in use at Kadena Air Base in Okinawa.

From the late 1970s to 1997, the U.S. government regularly imported PCBs. However, the last shipment from Japan was to Wake Island, an unincorporated territory of the United States, in spring 2000, the officials said.

A 2001 study indicated that there are some 3,118 metric tons of PCB-containing materials in use or in storage, including the weight of shipping crates. More than 70 percent, or 2,238 tons, of the toxin-laden materials are still in use. Government officials said there is no schedule for removing those still in use.

PCBs are used largely in electrical equipment, including transformers, condensers, voltage regulators and wiring. Military officials said there was little concern that PCBs might leach from underground wiring into the soil at military installations.