Chlorine dioxide is an extremely effective disinfectant, which rapidly inactivates bacteria, viruses parasites such as Giardia and to some extent, even the highly resistant encysted parasite Cryptosporidium. Chlorine dioxide’s combination of power and selectivity enable it to penetrate biofilms and destroy the resident microorganisms.
The inactivation of bacteria by chlorine dioxide has been attributed to the selective oxidation of nitrogen-nitrogen bonds in amino acids—hierarchically, tyrosine, tryptophan, cystine, cysteine—resulting in disruption of protein synthesis. In the case of viruses, chlorine dioxide is believed to denature the outer protein layers. Chlorine dioxide appears not to attack DNA or RNA, or to cause nucleic-acid leakage.