Officials at the Centers for Disease Control and Prevention, the federal agency that would be chiefly responsible for rushing medications to the site of an attack, told White House aides at a meeting Nov. 21 that they would not do so unless a BioWatch warning was confirmed by follow-up sampling and analysis, several attendees said in interviews.
Those extra steps would undercut BioWatch's rationale: to enable swift treatment of those exposed.
Federal officials also have shelved long-standing plans to expand the system to the nation's airports for fear that false alarms could trigger evacuations of terminals, grounding of flights and needless panic.
BioWatch was developed by U.S. national laboratories and government contractors and is overseen by the Department of Homeland Security. Department officials insist that the system’s many alerts were not false alarms. Each time, BioWatch accurately detected some organism in the environment, even if it was not the result of an attack and posed no threat to the public, officials said.
At the same time, department officials have assured Congress that newer technology will make BioWatch more reliable and cheaper to operate.
The current samplers are vacuum-powered collection devices, about the size of an office printer, that pull air through filters that trap any airborne materials. In more than 30 cities each day, technicians collect the filters and deliver them to state or local health labs for genetic analysis. Lab personnel look for DNA matches with at least half a dozen targeted pathogens.
The new, larger units would be automated labs in a box. Samples could be analyzed far more quickly and with no need for manual collection.
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Buying and operating the new technology, known as Generation 3, would cost about $3.1 billion over the next five years, on top of the roughly $1 billion that BioWatch already has cost taxpayers. The Obama administration is weighing whether to award a multiyear contract.
Generation 3 "is imperative to saving thousands of lives," Dr. Alexander Garza, Homeland Security's chief medical officer, told a House subcommittee on March 29.
But field and lab tests of automated units have raised doubts about their effectiveness. A prototype installed in the New York subway system in 2007 and 2008 produced multiple false readings, according to interviews with scientists. Field tests last year in Chicago found that a second prototype could not operate independently for more than a week at a time.
Most worrisome, testing at the Pacific Northwest National Laboratory in Washington state and at the Army's Dugway Proving Ground in Utah found that Generation 3 units could detect a biological agent only if exposed to extremely high concentrations: hundreds of thousands of organisms per cubic meter of air over a six-hour period.
Most of the pathogens targeted by BioWatch, scientists said, can cause sickness or death at much lower levels.
A confidential Homeland Security analysis prepared in January said these "failures were so significant" that the department had proposed that Northrop Grumman Corp., the leading competitor for the Generation 3 contract, make "major engineering modifications."
A spokesman for the department, Peter Boogaard, defended the performance of BioWatch. Responding to written questions, he said the department "takes all precautions necessary to minimize the occurrence of both false positive and false negative results."
"Rigorous testing and evaluation" will guide the department's decisions about whether to buy the Generation 3 technology, he said.
Representatives of Northrop Grumman said in interviews that some test results had prompted efforts to improve the automated units' sensitivity and overall performance.
"We had an issue that affected the consistency of the performance of the system," said Dave Tilles, the company's project director. "We resolved it. We fixed it.... We feel like we're ready for the next phase of the program."
In congressional testimony, officials responsible for BioWatch in both the Bush and Obama administrations have made only fleeting references to the system's documented failures.
"BioWatch, as you know, has been an enormous success story," Jay M. Cohen, a Homeland Security undersecretary, told a House subcommittee in 2007.