Chlorine dioxide (ClO2) is a broad-spectrum biocide with proven efficacy against a range of microbial organisms such as bacteria, viruses, protozoa, yeasts, mycobacteria and bacterial spores. Originally used in water treatment and food industries, chlorine dioxide has now been adopted as the go-to high-level disinfectant in medical, pharmaceutical, veterinary and laboratory settings.
The mechanism through which ClO2 achieves its potent biocidal effect is oxidation . Oxidation involves the oxidising agent sequestering electrons from the microorganism, which causes a molecular imbalance that inevitably leads to the microorganism’s death. The main advantage of using oxidising biocides over non-oxidising biocides (alcohols, quaternary ammonium compounds) is the inability for microorganisms to develop resistance , as well as the broad range of efficacy .
The comparison of ClO2 with other oxidisers, such as hydrogen peroxide is of interest. Whilst hydrogen peroxide and other oxidisers work through the same mechanisms as chlorine dioxide, they have been shown to be less effective against microbes . This is attributed to ClO2’s unique ability to penetrate the microorganism’s 3D protein structure  and, thus, better oxidise the molecules. Additionally, ClO2 forms no hazardous by-products  and is less harmful to people and equipment than other common biocides such as hydrogen peroxide and chlorine .
ClO2 is supported through the Biocidal Product Regulation for use in product types 2, 3, 4, 5, 11 and 12 and is also approved by the United States Environmental Protection Agency.
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