Chlorine dioxide (CAS 10049-04-4) is a highly potent agent with oxidizing, bactericidal, fungicidal, algaecidal and antiseptic properties. It is used in the pulp industry as a bleaching agent in combination with sodium chlorate (NaClO3) in a very low ratio of 1:170. However, this fact is irrelevant to its medical applications, since it is also used as a disinfectant in the public water supply for human consumption. Chlorine dioxide can be used both in gaseous form and dissolved in water, and the two forms are of considerably different toxicological significance.

Pure gas, in high concentrations, can cause irritation to the eyes, skin and respiratory tract of exposed persons. However, the most common exposure of the general population to chlorine dioxide is through consumption of disinfected water and is considered safe. In addition, it is not considered an environmentally persistent compound, as it degrades rapidly in water. 

There is no evidence to indicate immunotoxicity, reproductive toxicity or carcinogenicity of chlorine dioxide.


The dissolved form of chlorine dioxide in water can be rapidly absorbed through the gastrointestinal tract. Peak blood concentration levels can be reached within one hour after a single dose administered orally. It can also be absorbed slowly through the skin, with an absorption time of up to 12 hours. In high concentrations, in an occlusive manner, it may cause skin irritation. Chlorine dioxide is mainly metabolized to sodium chloride (common salt) and oxygen. Most of the administered chlorine dioxide and its metabolites remain in the blood, followed by the kidneys, lungs, stomach, intestine, liver and spleen, where they react rapidly with acids present such as lactic acid, uric acid, histamine or pathogens by oxidation. According to studies, approximately 43% of orally administered chlorine dioxide is eliminated in urine and feces within 72 hours. It is not excreted through the lungs. There is no evidence to suggest immunotoxicity, reproductive toxicity or carcinogenicity of chlorine dioxide.

LD50 oral rat
Value:292 mg/kg
JAT, Journal of Applied Toxicology. Vol. 2, Pg. 160, 1982. (Oficial EPA Data)
Logarithmic graph showing the lack of toxicity of chlorine dioxide at the doses used.

It has been observed that many media, especially in large chains, warn about the danger of chlorine dioxide based on an anecdotal testimony that lacks scientific basis. This testimony comes from a statement of the FDA (Food and Drug Administration, USA) and was copied by most health agencies in the world without any technical verification.

The statement warns about the danger of consuming chlorine dioxide, but does not specify any amount, concentration or duration of the alleged toxicity. In addition, they cite some cases of alleged poisoning citing the sodium chlorite precursor, which is a salt and not a gas like CDS, confusing these two substances in an ignorant, unprofessional or perhaps deliberate manner.

Claiming that a substance is toxic without providing accurate information supported by the toxic quantities is invalid by definition. Furthermore, no health agency can cite scientifically proven cases or studies to support this claim. Wikipedia warns about an alleged toxicity of CDS based on media and non-scientific articles, even alleging alleged deaths without citing sources or scientific veracity or allowing rectification evidenced with scientific studies from our side.

Any medical professional or toxicologist knows that any substance in very high quantities or concentrations can be toxic to the human body. The toxicity of chlorine dioxide (292 milligrams per kilogram) is similar to that of caffeine (367 milligrams per kilogram). This implies that a healthy 70 kg person would have to consume about 20,440 mg of a gas dissolved in water for 14 days to become intoxicated, which is impossible.

According to studies presented in an Environmental Protection Agency (EPA) report, the NOAEL has been determined to be 293 milligrams per kilogram of body weight per day. This is equivalent to 210 mg in a 70 kg person and 150 mg in a 50 kg person, with no toxic effects. This implies that, in theory, it is possible to increase the amount indicated in protocol C up to ten times without experiencing any intoxication, and the first light adverse effect would only be observed when multiplying the dose by twenty. It is important to note that this does not constitute a recommendation, but it clearly demonstrates the evidence of the non-toxicity of CDS.

The maximum amount recommended in the protocols is 30-60 mg daily in adults. To speak of a danger from the ingestion of chlorine dioxide in these quantities is completely absurd, especially after 16 years of experience in which no serious problems related to CDS have been recorded. Moreover, hundreds of thousands of people have shared their testimonials on the Internet confirming its efficacy and safety at the same time. Sadly this testimonies are often censored.