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.

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.)