Terrorist organizations continue to call for biological weapons attacks on the U.S., experts warn, yet our early warning system for bioterrorism is under attack in the Beltway.

BioWatch, launched in 2003 as the nation’s first early detection and warning system for biological attacks, scans for dangerous pathogens in urban areas and at key events such as the Super Bowl. It uses outdoor air-collection units taken daily by hand for pathogen testing.

The Federal government has already spent a billion dollars on the system, and it could sink $3 billion more into a planned, third-generation update -- and citing performance concerns, House Homeland Security Committee Democrats are crying foul.

'Bioterrorism remains a continuing threat to the security of our nation.'

— Assistant Secretary for Health Affairs Dr. Alexander Gaska

Amid stories of false alarms and false positives, they recommended that BioWatch contracts for billions be put on hold until the program and its goals are reexamined, citing the LA Times and a Government Accountability Office report released Thursday, Sept. 13.

"The concerns raised … mark an important opportunity to stop and reevaluate Gen-3 and assess where BioWatch fits into our federal biosurveillance efforts," said Rep. Laura Richardson (D-Calif.)

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In his testimony, Assistant Secretary for Health Affairs Dr. Alexander Gaska defended the program underscoring that “bioterrorism remains a continuing threat to the security of our nation. We know that terrorist organizations continue to call for chemical, biological, radiological, nuclear, and explosive attacks targeting the West.“

His response to Committee questions reinforced his July statement addressing the allegations of false positives: “Recent media reports have incorrectly claimed that BioWatch is prone to false positives or false alarms … these claims are unsubstantiated.”

“More than 7 million tests have been performed by dedicated public health lab officials and there has never been a false positive result,” he said.

Deployed in urban areas throughout the U.S. and at high profile political or sporting events, the program is a tool to detect intentional release of aerosolized biological agents.

Currently, BioWatch involves outdoor air-collection units, filters manually taken for pathogen testing every day by the Centers for Disease Control and Prevention.

After a sample is delivered, the results take approximately 8 to 10 hours; if DNA is present from a risk organism then a BioWatch Actionable Result (BAR) is declared by that public health laboratory director.

Gaska stressed a BAR means only that further information should be obtained, not that a terrorist attack has occurred or civilians exposed. A committee then meets to decide on further action.

Under the current BioWatch system, it may take up to 36 hours after a bioterrorism attack for the results to be available.

Many of the pathogens that could be deployed as a weapon also occur in nature.  Anthrax has been used as a weapon, for example, as in the 2001 attacks against two U.S. senators and several media agencies; it is also a bacteria found in the environment.

According to DHS, 52 instances of natural biological pathogens stemming from

environmental sources were reported in those 7 million tests.

Detection of a naturally occurring pathogen is not a false positive, yet this misconception seems to be fueling Congressional reservations.

The third generation of BioWatch would automate these tests through “labs in a box.” Gen-3 could reduce detection time to as little as 4 hours, providing more time for the authorities to react to a bioterror attack -- at a cost, however.

Approximately $1 billion has been spent on the system so far, and the next generation would run about $3 billion during its first five years. On Sept.

20, the Committee will revisit Generation 3 and make a decision.

Protecting Subways from Biological Attack

Meanwhile, DHS scientists began another phase of biodefense, focusing on bioterrorism attacks in public transportation.

Using Boston’s MBTA subway system, researchers from Argonne National Laboratory, Lawrence Berkeley National Laboratory, FLIR Systems Inc., and the British Defense Science and Technology Laboratory studied the eddies and air currents an airborne contaminant would follow if released.

Earlier phases focused on such contaminants within the system; this test explored how biological agents might spread out of the subway and above ground to a city at large.

The tests did not use any biological materials and instead involved non-toxic, inert, odorless gas and particle tracers: sulfur hexafluoride, used in outdoor and indoor air tests, and perfluorocarbons that are used in medical applications like eye surgery.

The researchers tagged these inert particle tracers an optical brightener used in laundry detergents. Then they took samples of particle and gas concentrations in more than 20 stations; testing encompassed the entire underground component of the Boston subway system as well as a number of above ground locations in Boston and Cambridge.

A chemical or biological attack launched in a subway was the primary focus, but the tests will also yield information for experts to better understand airflow relating to smoke in the event of a fire and risks resulting from accidental chemical spills.

This study will also help the MBTA to better refine incident response tactics from evacuation through to ventilation. The results will more widely support design of next generation chemical and biological agent detection systems.

Ballet dancer turned defense specialist Allison Barrie has traveled around the world covering the military, terrorism, weapons advancements and life on the front line. You can reach her at wargames@foxnews.com or follow her on Twitter @Allison_Barrie