Anthrax Lingers at Senate Building

Despite the fumigation two weeks ago of a small section of the Hart Senate Office Building, officials said Friday that trace amounts of deadly anthrax spores are still present.

Live anthrax spores were found in the office suite of Senate Majority Leader Tom Daschle (D-S.D.), which Environmental Protection Agency workers had pumped full of chlorine dioxide gas in an effort to rid the space of contamination.

The lingering anthrax was discovered in a follow-up on the effectiveness of the fumigation effort, which officials plan to extend to other contaminated areas of the building.

Of 380 samples taken in Daschle’s office, nine came back positive for anthrax, a result EPA officials said was “encouraging.”

“That means there is still some live anthrax there,” EPA spokeswoman Bonnie Piper said Friday. “We still have a ways to go to clean the building, but the use of the gas was so effective we are actually tonight going to fumigate a small portion of the ventilation system to see how well [the gas] performs there.”

And Piper said the cleanup, which has been going on around the clock, would be extended late Friday night to a fumigation of the southeast quadrant of Hart.

The process should take about 16 hours, she said, and will be followed by additional environmental sampling. Contaminated areas, she said, will likely require additional decontamination after the fumigation. The affected areas in Daschle’s office will now be treated with chlorine dioxide liquid.

The goal, Piper said, is “zero” contamination. Still, officials from the Centers for Disease Control and Prevention have cautioned that killing all remaining spores in any area exposed to widespread contamination may be difficult.

The challenge of ridding a facility of all anthrax contamination--and the fact that authorities are even trying--indicates a growing concern among scientists that no level of anthrax contamination is safe.

The Hart building was shuttered Oct. 17, two days after the anthrax-filled letter to Daschle was opened by an aide, releasing fine powder into the air.

Traces of anthrax spores were subsequently found throughout the building, including the offices of 11 senators.

Before the deaths of Ottilie W. Lundgren, 94, and Kathy T. Nguyen, 61, who had no obvious connection to contaminated mail or known exposure to the bacteria, federal health officials had assured a nervous public that trace amounts of anthrax posed little public health risk.

Now public health officials are saying far fewer spores may be needed to cause illness than they previously believed.

Since the anthrax mail attack was launched in September, five people have died and at least 13 others have been sickened by the disease.

Anthrax tests conducted on animals have found 8,000 to 10,000 spores are needed to infect half of those animals exposed--the level considered to be a lethal dose. But top health officials have conceded they have too little information to determine if a single spore might be enough to kill a highly vulnerable individual.

The lack of definitive research on the risk posed by a low number of spores--and the fact that medical ethics prohibit tests of highly lethal diseases on people--have made it difficult for federal officials to set policy regarding contaminated facilities.

How best to prevent the disease and what the exposure risks are in contaminated buildings are the subjects of a conference in Washington today. Some of the nation’s top anthrax researchers are scheduled to attend.

Postal hubs in Washington, D.C., and New Jersey that handled the anthrax letters remain closed, and a number of other facilities must still be decontaminated.