Larry Roberta’s every breath is a painful reminder of his time in Iraq. He can’t walk a block without gasping for air. His chest hurts, his migraines sometimes persist for days and he needs pills to help him sleep.

James Gentry came home with rashes, ear troubles and a shortness of breath. Later, things got much worse: He developed lung cancer.

David Moore’s postwar life turned into a harrowing medical mystery: nosebleeds and labored breathing that made it impossible to work, much less speak. His desperate search for answers ended last year when he died of lung disease at age 42.

What these three men — one sick, one dying, one dead — had in common is they were National Guard soldiers on the same stretch of wind-swept desert in Iraq during the early months of the war in 2003.

These soldiers and hundreds of other Guard members from Indiana, Oregon and West Virginia were protecting workers hired by a subsidiary of the giant contractor, KBR Inc., to rebuild an Iraqi water treatment plant.

The area, as it turned out, was contaminated with hexavalent chromium, a potent, sometimes deadly chemical linked to cancer and other devastating diseases.

No one disputes that. But that’s where the agreement ends.

Reform needed?

Among the issues now rippling from the courthouse to Capitol Hill are whether the chemical made people sick, when KBR knew it was there and how the company responded. But the debate is about more than this one case; it has raised broader questions about private contractors and health risks in war zones.

Questions, says Sen. Evan Bayh, who plans to hold hearings on the issues, such as these:

“How should we treat exposure to potentially hazardous chemicals as a threat to our soldiers? How seriously should that threat be taken? What is the role of private contractors? What about the potential conflict between their profit motives and taking all steps necessary to protect our soldiers?”

“This case,” says the Indiana Democrat, “has brought to light the need for systemic reform.”

For now, dozens of National Guard veterans have sued KBR and two subsidiaries, accusing them of minimizing and concealing the chemical’s dangers, then downplaying nosebleeds and breathing problems as nothing more than sand allergies or a reaction to desert air.

KBR denies any wrongdoing. In a statement, the company said it actually found the chemical at the Qarmat Ali plant, restricted access, cleaned it up and “did not knowingly harm troops.”

Ten civilians hired by a KBR subsidiary made similar claims in an arbitration resolved privately in June. (The workers’ contract prevented them from suing.)

This isn’t the first claim that toxins have harmed soldiers in Iraq and Afghanistan; there have been allegations involving lead, depleted uranium and sarin gas.

This also isn’t the first challenge to KBR, whose billions of dollars of war-related contracts have been the subject of congressional scrutiny and legal claims.

Among them are lawsuits recently filed in several states against KBR and Halliburton Co. — KBR’s parent company until 2007 — that assert open-air pits used to burn refuse in Iraq and Afghanistan caused illnesses and death. (KBR says it’s reviewing the charges. Halliburton maintains it was improperly named and expects to be dismissed from the case.)

Hexavalent chromium

This case stems from the chaotic start of the war in 2003 when a KBR subsidiary was hired to restart the treatment plant, which had been looted and virtually stripped bare.

The Iraqis had used hexavalent chromium to prevent pipe corrosion at the plant, which produced industrial water used in oil production.

It’s the same chemical linked to poisonings in California in a case made famous in the movie “Erin Brockovich.”

Hexavalent chromium — a toxic component of sodium dichromate — can cause severe liver and kidney damage and studies have linked it to leukemia as well as bone, stomach and other cancers, according to an expert who provided a deposition for the civilian workers.

The chemical “is one of the most potent carcinogens know to man,” declared Max Costa, chairman of New York University’s Department of Environmental Medicine.

KBR, however, says studies show only that industrial workers exposed to the chemical for more than two years have an increased risk of cancer — and in this case, soldiers were at the plant just days or months.

The company also notes air quality studies concluded the Indiana Guard soldiers were not exposed to high levels of hexavalent chromium. But Costa says those tests were done when the wind was not blowing.

Both soldiers and former workers say there were days when strong gusts kicked up ripped-open bags of the chemical, creating a yellow-orange haze that coated everything from their hair to their boots.

“I was spitting blood and I was not the only one doing that,” recalls Danny Langford, who worked for the KBR subsidiary. “The wind was blowing 30, 40 miles an hour. You could just hardly see where you were going. I pulled my shirt over my nose and there would be blood on it.”

Larry Roberta, a 44-year-old former Oregon National Guard member, remembers 137-degree heat and dust everywhere. He sat on a bag of the chemical, unaware it was dangerous.

“This orange crud blew up in your face, your eyes and on our food,” he says. “I tried to wash my chicken patty off with my canteen. I started to get sick to my stomach right away.”

Roberta had coughing spells and agonizing chest pains, he says, that “went all the way through my back. … Every day I went there, I had something weird going on.”