By now, emergency responders know the drill for dealing with suspicious white powder found in the office of the Senate majority leader.

A top official for the Environmental Protection Agency (search) said on Tuesday that she expects cleaning up after ricin (search) will pose "nowhere near the level of complexity" of anthrax (search), which took three months and cost at least $23 million to handle.

Tests confirmed it was an "active" form of the deadly poison ricin, found Monday in the mail room of Senate Majority Leader Bill Frist (search), R-Tenn. The six-story Dirksen Senate Office Building, where the substance was found, and the other two main Senate office buildings were closed. Congressional mail got a much closer look.

Senate officials again turned to the Environmental Protection Agency to decontaminate a Senate building.

On Oct. 15, 2001, it was a deadly anthrax bacteria, found in the mail room of then-Senate Majority Leader Tom Daschle, D-S.D. The nine-story Hart Senate Office Building closed for three months of cleaning. Around the nation, five people were killed and 17 sickened after coming into contact with letters containing anthrax.

Daschle drew a clear parallel between the two events. "Terrorists acts, criminal attacks of this kind, will not stop the work of the Senate or the Congress," he said Tuesday.

In both cases, the powders were analyzed by the Army Medical Research Institute of Infections Diseases at Fort Detrick, Md., where scientists conducted tests to verify the substances and determine just how dangerous they were.

Marianne L. Horinko, who heads EPA's Office of Solid Waste and Emergency Response, said the same team that handled the anthrax decontamination of the Hart building was assembling to deal with the ricin attack.

Three on-scene coordinators were dispatched Tuesday from EPA's Philadelphia regional office, said Horinko, who also was in charge of EPA's contribution to the cleanup at the World Trade Center site and the Pentagon after the terrorist attacks of Sept. 11, 2001.

The EPA teams will report to U.S. Capitol police. Experts in monitoring the safety of the air in and around the building were sent from New Jersey, along with other cleanup contractors.

"Our initial research is that this is nowhere near the level of complexity with the anthrax," she told The Associated Press.

Because ricin is a biological agent that typically can be cleaned up with a dilute bleach solution, she said, "I think it will not be anywhere near the scope" of the anthrax cleanup efforts.

It wound up taking three attempts to decontaminate the Hart building with poisonous chlorine dioxide gas and other techniques before it was finally declared "clean and safe" by the Centers for Disease Control and Prevention.

In November 2001, then-EPA Administrator Christie Whitman described those cleanups as "writing the book as we go along." She said decisions on how best to decontaminate a building must be custom-fit to each job and take into account the types of equipment, electronics and office furniture there.

In 1998, EPA gained responsibility for cleaning up buildings and other sites contaminated by chemical or biological agents due to terrorism. But the responsibility of "defining how clean is clean" so workers can reoccupy a building rests with CDC, not EPA, Whitman said.

Anthrax-laced envelopes were mailed in the fall of 2001 to government and news media offices, including those of Daschle and Sen. Patrick Leahy, D-Vt.