Patienteninformation zur Radontherapie

Presentation: Many people suffer from chronic illnesses associated with rheumatic pain. Radon, a naturally occurring radioactive inert gas, has had a reputation for being particularly effective in the treatment of these rheumatic diseases since ancient times. Due to the natural radioactivity of radon, there is uncertainty among patients who want to be cured and not be harmed by the therapy. This information document provides answers to the question about the possible risk of radon therapy.


Many people suffer from chronic illnesses that are associated with rheumatic pain. These so-called rheumatic diseases include, on the one hand, inflammatory changes in the joints and the spine, but also their signs of aging. Inflammatory joint diseases include chronic polyarthritis (rheumatoid arthritis); inflammatory diseases of the spine include damage to the intervertebral discs (osteochondrosis); and finally, joint wear and tear diseases include, for example, osteoarthritis of the hip and osteoarthritis of the knee and finger joints.

These diseases are treated with drugs called non-steroidal anti-inflammatory drugs (NSAIDs). In addition, radon, a naturally occurring radioactive noble gas derived from radium, has long enjoyed a reputation for the particular effectiveness of mineral sources in the treatment of these chronic rheumatic diseases. Non-steroidal anti-inflammatory drugs can, however, cause some damage to the stomach lining (ulcers, perforation or bleeding), or they can cause damage to the heart (heart attack, stroke).

Radon and its radioactive residues enter the patient's body directly through the skin during therapy in baths or inhalers (e.g. in thermal healing tunnels) or are inhaled with air and develop their healing effect there, especially on the immune system. Because of the natural radioactivity of radon and its residues, critics of radon therapy in baths or inhalers have deduced a lung cancer risk for the patient and have equated it with the risk of lung cancer due to radon in apartments with higher radon concentrations.

The result is uncertainty for the patient who wants to be cured and does not want to be harmed by the therapy. This is why doctors, biophysicists and radiation protection experts (P. Deetjen, A. Falkenbach, D. Harder, H. Jöckel, A. Kaul, H. von Philipsborn) have addressed this issue. They published the results of their investigations under the title "Radon als Heilmittel – Therapeutische Wirksamkeit, biologischer Wirkungsmechanismus und vergleichende Risikobewertung" (2005, Verlag Dr. Kovac, Hamburg) as well as more recent results. A publication by RADIZ (29/2009, A. Kaul) is devoted to the basic principles, successful healing and possible side effects of radon therapy as information for patients and physicians. It has been revised with the attached information brochure and supplemented with the new results of the risk assessment. It also explains to the reader why the reference value for radon concentrations in buildings, adopted by the European Union in 2013, cannot be applied to radon balneotherapy.

Thanks to the scientific results of the study "Radon als Heilmittel..." and the information brochure, the patient can get an answer to his question about the possible risk of radon therapy :

Dear patients,

Medical measures are sometimes associated with undesirable side effects for the patient. These are taken into account by the doctor when deciding which measure to choose in each individual case to cure a disease. His or her decision is always based on the balance between the benefit of care for the patient and the possible risk of undesirable side effects.

This applies both to pain and anti-inflammatory therapy for chronic rheumatic diseases, which are treated with non-steroidal anti-rheumatic drugs (NSAIDs), and to radon balneotherapy, in which patients are in baths or inhalers.

NSAIDs act as anti-inflammatory and analgesics (pain relievers) by inhibiting the biosynthesis of socalled mediators of the inflammatory response and pain sensation. Undesirable side effects, which cannot be ruled out with long-term use, may manifest themselves as superficial mucosal damage, bleeding ulcers in the gastrointestinal tract or even perforation (stomach perforation). Recently introduced "modern" NSAIDs for therapy, called coxibes, present a much lower danger to the mucous membrane of the stomach and intestines, but may increase the risk of cardiovascular complications (heart attacks, strokes).

Radon therapy in bathtubs or inhalers is based on the biological effect of radon, a naturally radioactive noble gas, and its radioactive residues on the immune system. It generally results in more lasting pain relief, which has been proven by long-term clinical studies (see above: "Radon als Heilmittel – Therapeutische Wirksamkeit, biologischer Wirkungsmechanismus und vergleichende Risikobewertung"). In addition to this pain relief over months or even years, the significant reduction in medication use and the resulting reduction in drug-related risk is an aspect not to be underestimated in the decision process between radon therapy and drug therapy.

 Apart from this curative effect of radon, a naturally radioactive noble gas, undesirable radiation-related effects cannot be excluded in principle, but are extremely unlikely. Radon has caused lung cancer in uranium miners and has been known to cause lung cancer in buildings with high radon content with a probability in the order of a percentage. However, in the case of therapeutic application of radon in a bath or inhaler or a cure through drinking, the probability of such an effect is a very small fraction of that, if any, that exists. This can be seen from the following facts: 

  1. The radiation from a radon treatment in a bathtub or inhaler is at most equal to or much less than the natural background radiation and its fluctuation range to which each person is exposed over a full year (see "Radon as a remedy..."). The average value of the natural radiation dose in Germany is about 2 mSv/a (milli-Sievert per year), the fluctuation range is about 1 mSv/a to 10 mSv/a. The level of this natural radiation dose is mainly determined by the geological characteristics of the region in which one lives, i.e. mainly by the uranium and radium content of the minerals in the soil.
  2. A patient's additional exposure to radon resulting from several cures over the course of his or her lifetime, due to the relatively short time spent in the bath or inhaler, is no more than one tenth of the average radon exposure in buildings (such as houses) and outdoors over an average life of 75 years.
  3. It has not yet been scientifically proven that additional exposure to radon at such low levels in a home is capable of increasing the risk of spontaneous lung cancer in all individuals. However, as a precautionary measure, as is generally the case in radiation protection, experts have made the following theoretical estimate, which is deliberately pessimistic: If we consider all radon exposures averaged over a patient's lifetime, and if we do not take into account the biological adaptation mechanisms (repair mechanisms), we obtain a hypothetical lung cancer risk of about one hundredth of the spontaneous lung cancer risk of our population. This figure is currently about 5% on average for non-smokers and smokers.
  4. The actual risk of drug-induced mortality observed in statistical surveys due to so-called nonsteroidal anti-rheumatic drugs, on the other hand, is significantly higher than the hypothetical risk of lung cancer theoretically calculated with radon therapy.
  5. Taking into account these theoretically calculated risks, if any, of radon therapy, which are very low compared to the actual risks of drug therapy, the doctor will decide on the type of therapy indicated in each individual case based on the patient's individual health problem. This means that he is always looking for optimal benefits for each patient in terms of minimizing undesirable side effects. Even the hypothetical risk of lung cancer calculated under pessimistic assumptions for radon therapy of so-called rheumatic diseases should not be considered as limiting the benefit of this therapy. It is rather small compared to the health risks of drug therapy.

The statements made above under points 1-3 and 5 concerning the radiation dose to patients undergoing radon treatment are not affected by the reference value for radon concentration in domestic or commercial indoor spaces of 300 Bq/m3 (Becquerel per cubic metre) mentioned in the European Union Directive of 5.12.2013.

The reasons for this are as follows:

  1. The reference value refers to radon in buildings where people can stay permanently, not to patients whose stay in radon bathtubs or inhalers is relatively short during a cure, even if repeated cures are performed over a lifetime.
  2. Even the minimum radon concentration in bathing water of 666 Bq/l, which is required for a radon cure in water, leads to radon concentrations in the indoor air of the therapy centre that are significantly lower than the EU reference value for premises intended for permanent residence of members of the general population. Even in the premises of a radon therapy facility with bathtubs with concentrations well above 666 Bq/l of water, the indoor air concentration is only insignificantly above the EU reference value, if at all, and is not relevant to the short periods of stay of other people in the therapy rooms.
  3. Unlike patients, staff stay in the therapy rooms for an average annual stay of 2,000 hours, which is assumed to be the maximum, on average about 500 times longer than patients during a full radon cure, without the resulting radiation dose reaching or even exceeding the fluctuation range of natural radiation exposure. On the contrary, these occupationally induced radiation doses also remain well below the legally stipulated limit value of 20 mSv/a for this group of people in the Radiation Protection Ordinance.

In summary, the EU reference value of 300 Bq/m3 for radon concentration applies only to permanent residence in domestic or commercial indoor environments. It is therefore not applicable and restrictive for the temporary medical use of radon for curative purposes. And even for staff working in radon spas, the EU value does not have a restrictive effect due to temporary residence and the radiation protection measures taken there, since the limit values set in the Radiation Protection Act are binding for occupationally exposed employees.

This means that the value of the EU - although not relevant for patients, as explained above - does not restrict the validity of the statement made in point 3:

The calculated risk of lung cancer for patients of a radon treatment in the bathtub and even by inhalation is at most one hundredth of the risk of spontaneous lung cancer in our population - including smokers.

Prof. Dr. Alexander Kaul

Member of the scientific advisory board of the "Radon Revital Bad”

Former President of the Federal Office of Radiological Protection, Berlin