Is chlorine dioxide harmful in drinking water?

Scientific facts and studies on safety and efficacy

We are occasionally asked whether chlorine dioxide in drinking water is harmful to the human body. Since we don't want to answer this question with our own subjective, positive experiences, we will let the scientific facts speak for themselves.

First of all, many people mistakenly equate chlorine dioxide with chlorine . However, this is completely wrong!

Chlorine has the negative property of forming compounds with other substances. This can lead to the formation of new, toxic substances.
However, this problem does not occur with chlorine dioxide , as it is a chlorine-oxygen compound which therefore does not form any further compounds with other substances.

Excerpt from Wikipedia:
" Chlorine is one of the most reactive elements and reacts with almost all other elements and many compounds. This high reactivity also explains the toxicity of elemental chlorine ... Since the reaction with other components of water can also produce undesirable and sometimes toxic or carcinogenic substances, such as trihalomethanes, chlorine is increasingly being replaced by chlorine dioxide or ozone for the disinfection of drinking water."

Scientific studies on the use of chlorine dioxide in drinking water

We would now like to draw attention to some scientific studies that have investigated the use of chlorine dioxide in drinking water. These studies have repeatedly demonstrated not only its safe and side-effect-free use at high concentrations, but also its high efficacy against many types of viruses, bacteria, fungi, Legionella, and even parasites.

Studies on the safety of chlorine dioxide at high concentrations

1. Controlled clinical evaluations of chlorine dioxide, chlorite and chlorate in man – Ohio State University, Department of Pharmacology
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569027/

   A highly publicized study from the Department of Pharmacology at Ohio University (USA). In the first part of the study, participants were administered progressively increasing concentrations of chlorine dioxide over 16 days. On the last day, the concentration was 24 mg/L .
   In part 2, the test subjects drank 500 ml of solution with a chlorine dioxide content of 5 mg/L daily for 12 weeks.

   Result (translated): "No adverse effects were observed by either the participants or the investigating medical team." And: "The absence of harmful physiological reactions during the study demonstrated the relative safety of oral ingestion of chlorine dioxide and its degradation products."

2. Toxicological effects of chlorite in the mouse – University of Massachusetts, Division of Environmental Health
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569033/

   In this study from the University of Massachusetts (USA), mice were given drinking water containing 100 mg/L of chlorine dioxide daily for 30 days. The mice were examined for changes in their blood – however, none were found.

3. Subchronic toxicity of chlorine dioxide and related compounds in drinking water in the nonhuman primate – US Environmental Protection Agency
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1569048/

   In this study, the US Environmental Protection Agency administered drinking water containing between 30 and 100 mg/L of chlorine dioxide to several monkeys over several weeks. No hematological or other changes were observed. Only after four weeks of ingestion at a concentration of 100 mg/L was there a temporary decrease in thyroxine levels.

To make the studies easier to understand:
One milliliter of 0.3% chlorine dioxide solution contains 3 mg of pure chlorine dioxide. Therefore, a chlorine dioxide concentration of 24 mg/L corresponds to 1 liter of water containing 8 ml of 0.3% chlorine dioxide solution.

Studies on the effectiveness of chlorine dioxide against pathogens

Numerous studies have demonstrated the effectiveness of chlorine dioxide against pathogens. These studies show high efficacy not only when used in drinking water, but also, for example, when used in indoor air to combat mold, as a surface disinfectant, or even in oral hygiene.

Since we cannot present all studies, we show some interesting examples here. Many more can be found in the US National Library of Medicine .

1. Effect of disinfection of drinking water with ozone or chlorine dioxide on survival of Cryptosporidium parvum oocysts
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC202897/

   In this study, drinking water contaminated with Cryptosporidium parasites (related to the malaria pathogen) was treated with 0.31 mg/L chlorine dioxide. After an exposure time of only 16 minutes, 97% of the parasites were already killed.

2. Effect of Chlorine Dioxide Gas on Fungi and Mycotoxins Associated with Sick Building Syndrome
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1214660/

   A room contaminated with four different types of mold was treated with chlorine dioxide gas (500 ppm) and sealed for 24 hours. This resulted in the complete destruction of three mold species and 90% destruction of one species.

3. Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial
   http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2831889/

   In this randomized, placebo-controlled, double-blind study, the effect of chlorine dioxide mouthwashes was tested on 15 men. Chlorine dioxide mouthwashes were used twice daily for seven days. A significant reduction in halitosis, plaque, tongue coating, and bacterial count in the oral cavity was observed.

   Note: Our chlorine dioxide products are approved exclusively for drinking water treatment. The study serves only as an example of the effectiveness of chlorine dioxide in various applications.

All studies mentioned here can be found in the US National Library of Medicine via the links provided.