Chlorine dioxide for the use of water purification has been well studied. In those studies the scientists and doctors observed that chlorine dioxide quickly breaks down in the bodies of animals. In one study chlorine dioxide in solution was pumped into the stomach of monkeys and then removed after about 5 minutes. They observed that 95% of the oxidation potential of the chlorine dioxide was lost in that amount of time.
Other studies have shown that chlorine dioxide breaks down to around 70% chlorite and 30% chloride inside the body. The chlorite penetrates all organs of the body, and has a half life of a little over 40 hours. Chlorite levels are monitored closely in water treatment because chlorite damages red blood cells. The levels allowable in water treatment are very low, but there was one study done with humans at a level 5 times higher than the allowable limits. This study was conducted over 12 weeks and no adverse effects were observed. However, this study was done with chlorine dioxide in water and did not involve ingesting acidified sodium chlorite solutions.
I believe Jim Humble has all of these studies listed on his information site.