[en] The World Health Organization (WHO) recognizes the social and economic importance of utilizing ionizing radiation for the benefit of humankind and that exposure to radiation is a natural and unavoidable consequence of living on Earth. However, exposure to radiation, both human-made and natural, can be detrimental to health. Thus, there is a need to balance the benefits from the use of radiation against the risks of consequential exposure, to ensure a net benefit. This need can only be met by developing a sound knowledge of the effects of radiation exposure on health. Thus, in the area of ionizing radiation, as well as in other areas, the WHO is striving to achieve safe, sustainable and healthy human environments, protected from biological, chemical and physical hazards, and secure from the adverse effects of global and local environmental threats. As a directing and co-ordinating authority on international health work within the United Nations system, the WHO evaluates health risks related to radiation exposure and provides advice to national authorities. Ionizing radiation is receiving an increased priority within the WHO. (author)