Your Drinking Water may contain RADON

Radon is a natural radioactive gas, originating from uranium which occurs in many types of rock. All water and air contains some radon, though levels are normally much too low to be of concern. For many years it has been recommended that, if the concentration of radon in indoor air exceeds the Action Level of 200 becquerels per cubic meter, steps should be taken to reduce it. It is now recognized that some private water supplies contain levels of radon which should also be controlled. However, it is important to recognize that radon in water almost certainly presents a smaller public health hazard than radon in air, both in term of the numbers of people exposed to high levels, and in terms of the risks to the most exposed individuals.

The European Union (EUW) is considering a draft recommendation on the protection of the public against exposure to radon in water supplies. The EU is proposing:

• for private water supplies that are part of a commercial or public activity (e.g.
  hotel or bed and breakfast) remedial action should always be taken when the
  radon concentration exceeds an Action Level of 1000 becquerels per liter.
• for individual water supplies (no commercial or public activity) consideration
  should be given to remedial action when the radon concentration exceeds an
  Action Level of 1000 becquerels per liter.

This Action Level of 1000 becquerels per liter is set so that the risk to a typical person drinking such water is similar to, but probably a little lower than, the risk which would arise from breathing air which contains radon at the Action Level of 200 becquerels per cubic meter. This comparison takes account of the different way that radon affects the body if swallowed, compared to being breathed in.

All exposures to radiation are assumed to carry some risk, though the risks from very low doses are very small. The Action Level does not mark a boundary between safe and unsafe, but rather a level at which action will usually be justified. Some people may choose to take action when the Action Level is approached.

Information from the Committee on Medical Aspects of Radiation in the Environment (COMARE) on radon contamination of UK private water supplies is available.

Further information

NRPB/Faculty of Public Health Medicine/Chartered Institute of Environmental Health. Health risks from radon. NRPB, Chilton (2000).

NRPB. Estimates of late radiation risks to the UK population. Doc. NRPB, 4, No. 4, (1993).

NRPB. Risk of radiation-induced cancer at low doses and low dose rates for radiation protection purposes. Doc. NRPB, 6, No. 1, (1993).

National Research Council. Risk assessment of radon in drinking water. National Academy Press, Washington, DC (1999).

National Research Council. Health effects of exposure to radon: BEIR VI. National Academy Press, Washington, DC (1999).