Two subcontractors who say they were exposed to poison chemical agents while working on a construction project at the Army's Dug-way Proving Ground filed a $1 million federal suit against the government Tuesday.

Mark Oakes and Bruce Oakes, who are subcontractors of Project Unlimited, claim in the suit that on June 17, 1986, excavators uncovered several canisters believed to contain toxic agents used in chemical warfare. The concealed or buried canisters were not disclosed to the Oakes or the prime contractor, the suit says."Upon exposure, the . . . canisters began emitting vaporous gases," the suit says. Plaintiffs and several co-workers became ill and fled. Three days later, Army officials said the substances were not dangerous, the canisters had been removed and it was safe to return to the job site.

When excavation resumed nearby, "additional chemical canisters were exposed," and the plaintiffs were again subjected to dangerous chemicals, the suit says.

A claim against the Army has not been accepted or rejected and now the plaintiffs seek at least $500,000 each, plus special damages.