WASHINGTON - Preparing to face chemical and biological weapons for the first time in 85 years, U.S. troops sent into Iraq will carry equipment that leaves them vulnerable to an attack.

Facing this risk, the Pentagon has come under fire for making slow or insufficient progress in protecting its troops against gas and germs, despite advances in protective gear and detectors since Desert Storm.

Congressional analysts, outside experts and defense planners and even some Pentagon officials have pointed to these problems:

Biological weapons detectors don't register an attack until about a half-hour after exposure, meaning soldiers would first know they were being attacked with anthrax or botulinum toxin only after the fact. Chemical weapons detectors are more advanced, warning of dangers as far as three miles off.

But even chemical detectors don't pick up common but deadly compounds, such as chlorine gas, used by the Germans in World War I. Also, these units easily can be fooled by putting an innocuous chemical coating on the deadly agents.

Half of 20,000 gas masks tested at random during a 1999 study were found to have "critical defects" that could render them useless in an attack.

Hindrance in battle

U.S. troops now have cooler protective suits than during Desert Storm. But some outside experts charge that the Pentagon underestimates how difficult it is to fight while wearing the gear, with some saying soldiers could be at 25 percent to 50 percent of normal effectiveness in Iraq's searing heat.

The new suits' carbon-based liner begins to degrade when exposed to something expected to be a significant factor in the Iraqi desert - sweat. U.S. officials acknowledge the problem but say the suits can be replaced on the battlefield before they lose their protective ability.

War planners worry that U.S. troops are more likely to face Iraqi President Saddam Hussein's most horrific weapons this time because the United States has served notice that Hussein's days are numbered in the face of an American onslaught. Iraq didn't use mass-destruction weapons during the 1991 Persian Gulf war.

In the realm of battlefield hazards, biological weapons are the most insidious. Chemical weapons such as sarin or mustard gas kill quickly but their deadly effects can fade quickly in combat. Biological weapons can take days to show themselves, with some, such as smallpox, killing slowly and passing easily from person to person.

'Highly vulnerable'

Many experts believe U.S. troops could fight through a chemical attack but fear that a bio-attack would be crippling.

"We are highly vulnerable to even small-scale biological attacks," said retired Air Force Col. Randy Larsen, former head of military strategy at the National War College, a military school for commanders and civilian leaders.

For Maj. Gen. John Doesburg, head of the U.S. Army Soldier and Biological Chemical Command, bioweapons are "what keeps me awake at night. ... You can't see them, you can't touch them, you can't smell them."

What Pentagon planners fear most is a weapons of mass destruction attack against massed U.S. troops, perhaps one that could shut down a port or an airfield, a strategy Hussein used effectively in the Iran-Iraq war.

Still, Doesburg and other top officials strongly dispute assertions that U.S. troops are being sent into battle without adequate protections or that the Pentagon hasn't pushed hard enough to make strides ahead of a possible Iraqi invasion.

Today, the Pentagon is fielding 22 new systems developed in the past 12 years, including 10 new detectors. Troops facing a chemical weapons attack today would be given ample warning to don protective gear. About 500,000 troops are expected to be vaccinated against smallpox.

The Pentagon hopes to prevent Hussein from using the weapons by persuading his generals to disobey orders - or face war crimes charges. Knocking out Scud missile launchers and weapons plants will be an early priority in any invasion.

But the trick of detecting a biological attack remains elusive because detectors aren't sophisticated enough to distinguish between a bioweapons cloud over the horizon and one of a harmless natural substance such as pollen, Doesburg said.

The Pentagon is working on a smaller and easier-to-operate biodetector but none has been given to troops. The Pentagon had hoped to buy 143 units last year but obtained only five, according to a Pentagon report, and now is seeking proposals from manufacturers to build several hundred.

Gas mask problems uncovered in 1999 resulted from poor upkeep as well as manufacturing defects. Army officials dispute the findings, saying all but about 10 percent of problems were easily correctable through better maintenance.

The new chemical suit is cooler and more durable than one used during Desert Storm, but special forces soldiers have raised the concern that sweat and sea water can degrade the suits and weaken their effectiveness against an attack.

Army Brig. Gen. Stephen Reeves, program executive for chemical and biological defense, acknowledged that sweat degrades the carbon liners in current suits but said the Pentagon took that into account when setting its 45-day life cycle.

Meanwhile, the Pentagon still can't account for 250,000 older-model suits known to be defective, though they were recalled in 2000. U.S. officials say they are confident no front-line troops have the suits but can't say for sure where they are.

Pentagon officials declined to give a specific estimate of how much a soldier's skills are impaired while wearing the suits and masks, though studies show the mask can reduce a soldier's aiming ability by 20 percent.

Jack Sawicki, technical director of homeland security for Versar-Geomet, a Virginia company that develops and tests personal protective equipment, believes a soldier's effectiveness while in the suit can be reduced as much as 50 percent to 75 percent by heat stress, difficulty breathing through a gas mask, reduced field of vision and other hindrances.

That's what makes fighting in the suits so dangerous, particularly in the type of urban environment that U.S. soldiers could face in a fight to take Baghdad, Sawicki said.

Craig Gordon writes for Newsday, a Tribune Publishing newspaper.