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.)

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."