The biodefense lab at Fort Detrick in Frederick began a thorough search of its freezers yesterday to ensure that it has an accurate inventory of the deadly bacteria, viruses and toxins accumulated there over a period of 40 years, Defense Department officials said.
Col. John P. Skvorak, commander of the U.S. Army Medical Institute of Infectious Diseases, ordered a "stand-down," or pause in ordinary operations, and a complete inventory last week after 20 vials of "biological select agents and toxin" (BSAT) were discovered in a freezer box that was listed as containing only 16 vials.
Army officials insisted there are no missing vials of lethal substances and no danger to the public.
They said the problem lies with unused, older samples of research materials that were in storage before the institute's records were computerized in 2005.
Until then, the inventory of deadly stocks was kept on paper by hand.
"It's a record-keeping thing," said Caree Vander-Linden, a spokeswoman for the institute.
Accounting for all the material in the institute's freezers and refrigerators could take three months.
"We are not going to sacrifice accuracy for speed," she said.
Authorities moved quickly to begin to resolve the discrepancies, given the institute's role in the 2001 anthrax mailings that killed five people.
Bruce Ivins, who was identified by federal authorities last year as the perpetrator of the mailings, was an anthrax researcher at the institute when he killed himself in July after learning he was about to be charged with the crimes by the FBI.
In a memo to his staff last week, first reported by the blog ScienceInsider, Skvorak said the "probability that there are additional vials of BSAT not captured in our [computerized] data base is high."
He said he was ordering the stand-down and a suspension of some research until "a full certification" of the contents is complete.
Reporting of such discrepancies is required under tightened regulations adopted last month by the Defense Department in the wake of the Ivins case, in which authorities say the researcher was able to divert deadly anthrax without being detected.
Any material that is not properly accounted for, including material on hand that is not in the computer database, must immediately be reported to the Army vice chief of staff, Gen. Peter Chiarelli.
Officials in his office were not available for comment yesterday.
Outside Fort Detrick, some scientists were not so quick to dismiss the incident as a harmless record-keeping problem.
"If there are [bioweapons] samples that are undeclared, unaccounted for, those samples can be stolen or diverted with no means of detection," said Richard H. Ebright, a molecular biologist at Rutgers University.
He said such discrepancies "happen all the time" in normal laboratory environments, "but when it happens in a lab handling bioweapons, that's a serious concern."
Ebright acknowledged that security measures at Detrick "are substantially more stringent" than at civilian government and academic labs that handle lethal material.
There are about 400 research labs that handle lethal material in the United States, he said.
The research at the Institute of Infectious Diseases is designed to examine highly hazardous biological agents in order to design effective protection in the form of vaccinations or antidotes.
It is the government's premier research lab on biological warfare defenses.
Skvorak said that animal research currently under way at the institute will continue during the inventory process.