By Rajini Vaidyanathan
BBC News, Washington
Sixteen American soldiers who served in Iraq are suing the defence contractor KBR, accusing it of knowingly exposing them to a cancer-causing chemical.
The soldiers say they were exposed to the chemical while working at a water pumping plant in southern Iraq.
Their lawsuit, filed in a US District Court, claims that KBR managers knew the site was contaminated but "downplayed and disregarded" the risk.
KBR denies the accusation and has vowed to fight the lawsuit.
The claims go back to 2003, when the soldiers, from the Indiana National Guard, were protecting the Qarmat Ali water pumping plant in Southern Iraq.
The 23-page lawsuit argues that KBR managers knew as early as May of that year that the site was contaminated with sodium dichromate, which contains the highly dangerous chemical hexavalent chromium, said to cause cancer.
The soldiers say that they and other civilian contractors there were repeatedly told there was no danger, and that when they reported health problems such as nose-bleeds to their bosses, they were told they were simply "allergic to the sand".
The court papers claim that these symptoms were the early side-effects of the chemical, and that some who served on the site went on to suffer severe breathing problems and nasal tumours.
In a statement issued to the BBC, KBR said it intended to vigorously defend itself.
It denied it harmed troops, saying that managers notified army engineers about the substance on site, and were told that their efforts to remedy the situation were effective.