The concern was over the disinfection by product chlorite. Abdel-Rahman et all discovered that the disinfection by product of chlorine dioxide used to purify water was chlorite. They ran tests and found that the half life of chlorite in animals was a little over 40 hours.
Chlorite is a free radical in the body and taking antioxidants neutralizes this free radical as it is eliminated from the body.
If you have a link to studies done showing something different please post them. If not, we will just have to go with the studies already done.