A group of Indiana soldiers returned safely from Iraq, but may still be in a life-threatening situation.

A letter of caution has been sent to roughly 600 members of the Indiana National Guard.

But, it may have come too late for the family of National Guard Sergeant David Moore.

Senate hearings in June revealed sodium dichromate was used at a water treatment plant near Basra, Iraq between May and September in 2003.

The 42-year-old had served near the plant during that timeframe.

After returning home to Jasper, Indiana in 2004 his health got progressively worse and his lung collapsed.

Those soldiers who did receive a letter will likely get a second one--further advising them what steps to take.