FEATURES Radiation safety: New international standards The forthcoming International Basic Safety Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources are the product of unprecedented co-operation by Abel J. B*y the end of the 1980s, a vast amount of new This article highlights an important result of Gonzalez information had accumulated to prompt a new this work for the international harmonization of look at the standards governing protection radiation safety: specifically, it presents an over- against exposures to ionizing radiation and the view of the forthcoming International Basic safety of radiation sources. Safety Standards for Protection Against Ionizing First and foremost, a re-evaluation of the Radiation and for the Safety of Radiation Sour- radioepidemiological findings from Hiroshima ces — the so-called BSS. They have been jointly and Nagasaki suggested that exposure to low- developed by six organizations — the Food and level radiation was riskier than previously es- Agriculture Organization of the United Nations timated. (FAO), the International Atomic Energy Agency Other developments — notably the nuclear (IAEA), the International Labour Organization accidents at Three Mile Island in 1979 and at (ILO), the Nuclear Energy Agency of the Or- Chernobyl in 1986 with its unprecedented ganization for Economic Co-operation and transboundary contamination — had a great ef- Development (NEA/OECD), the Pan American fect on the public perception of the potential Health Organization (PAHO), and the World danger from radiation exposure. Accidents with Health Organization (WHO). radiation sources used in medicine and industry also have attracted widespread public attention: Cuidad Juarez (Mexico), Mohamadia (Moroc- The framework for harmonization co), Goiania (Brazil), San Salvador (El Sal- vador), and Zaragoza (Spain) are names that ap- In 1991, within the framework of the Inter- peared in the news after people were injured in agency Committee on Radiation Safety, the six radiation accidents. Furthermore, the decade saw organizations created a Joint Secretariat under the rediscovery of natural radiation as a cause of the co-ordination of the IAEA. The action concern for health: some dwellings were found capped decades of continuing efforts and marked to have surprisingly high levels of radon in air; an unprecedented international co-operation that natural radiation exposures of some non-radia- has involved hundreds of experts from the Mem- tion-related workers were discovered to be at ber States of the sponsoring organizations for levels much higher than the occupational limits establishing the BSS. These international stand- specified in recognized standards. ards supersede any previous ones in the field of Following these developments, the Interna- radiation safety, in particular those developed tional Commission on Radiological Protection under the auspices of the IAEA. (See box, next (ICRP) in 1990 revised its standing recommen- page.) dations. The concerned organizations of the Radiation effects. From the time of early United Nations family and other multinational studies on X-rays and radioactive minerals it was agencies promptly followed by triggering a recognized that exposure to high levels of radia- review of their own standards. tion can harm exposed tissues of the human body. These radiation effects can be clinically diagnosed in the exposed individual; they are called deterministic effects because, given a Dr Gonzalez is Deputy Director of the IAEA Division of radiation dose, they are determined to occur. Nuclear Safety. Posteriorly, long-term studies of populations ex- IAEA BULLETIN, 2/1994 FEATURES A number of bodies have supported the United Nations Scientific Committee on International work to harmonize international radiation the Effects of Atomic Radiation (UNSCEAR). harmonization in safety standards which draw upon information In developing the BSS, UNSCEAR provided radiation safety derived from extensive research and develop- the scientific information on which the stand- ment by scientific and engineering organiza- ards are based. The Committee — which was tions at national and international levels. For established by the UN General Assembly in its part, the IAEA has the statutory authoriza- 1955 and today includes representatives from tion to establish or adopt, in consultation and, 21 countries — compiles, assesses, and dis- where appropriate, in collaboration with the seminates information on the health effects of competent organs of the United Nations and radiation and on the levels of radiation ex- with the specialized agencies concerned, posure from different sources. standards of safety for protection of health...". International Commission on Radiologi- In discharging this function, the IAEA Board of cal Protection (ICRP). Radiation safety stand- Governors first approved Agency health and ards are based on the recommendations of the safety measures in March 1960. The Board ICRP, a non-governmental scientific organiza- approved the first version of the IAEA's Basic tion founded in 1928. Its most recent recommen- Safety Standards for Radiation Protection in dations were issued in 1990 (Publication 60, June 1962 and a revised version in September Annals of the ICRP, Vol. 21, No.1-3)) and form 1965. A third revision was published by the IAEA the basis of the BSS. as the 1982 Edition of Safely Series No. 9; this International Commission on Radiation edition was jointly sponsored by the IAEA, fie Units and Measurements (ICRU). The quan- ILO, the OECD/NEA, and the WHO.* tities and units used in the BSS are primarily The Inter-Agency Committee on Radia- those recommended by the ICRU, a sister or- tion Safety (IACRS). A number of years ago, ganization of the ICRP. (See box, next page.) the IAEA promoted the formation of IACRS as The International Nuclear Safety Ad- a mechanism for consultation and collabora- visory Group (INSAG). This advisory body of tion in radiation safety matters with competent nuclear safety experts serves as a forum for organs of the United Nations and with the the exchange of information and for the specialized agencies. The Committee aims provision of advice to the IAEA on safety is- inter alia to encourage the co-ordination of sues of international significance. In 1988, it policies and consistency in radiation safety issued through the IAEA the Basic Safety Prin- principles and standards. Members are the ciples for Nuclear Power Plants (Safety Series FAO, ILO, NEA/OECD, PAHO, UNSCEAR, No. 75-INSAG-3). Many of these principles are WHO, Commission of the European Com- relevant to the safety of other radiation sour- munities (CEC) and the IAEA. A number of ces and installations and have been used in organizations — the ICRP, the International the BSS. Commission on Radiation Units and Measure- ments (ICRU), the International Electrotechni- cal Commission (IEC), the International Radiation Protection Association (IRPA) and * For a description of these previous international the International Standards Organization standards see the author's article in the IAEA Bul- (ISO) — have observer status. letin; Vol. 25, No. 3; (September 1983). posed to radiation, especially of the survivors of the advance, may be expected to increase the back- atomic bombing of Hiroshima and Nagasaki, have ground exposure that people already receive: demonstrated that exposure to radiation also has a they are termed practices. potential for the delayed induction of malignancies On the other hand, there are radiation ex- and possibly of hereditary effects. These radiation posures incurred de facto by people. The ac- effects cannot be related to any particular in- tivities which are intended to reduce these ex- dividual exposed but can be inferred from posures are termed interventions. epidemiological studies of large populations; Because of the radiation effects on health, they are called stochastic effects because of their practices and interventions need to be subject to aleatory statistical nature. (See box, next page.) certain standards of radiation safety to protect Human activities and radiation exposure: those persons adventitiously exposed.The BSS practices and interventions. Many beneficial are intended to harmonize internationally the human activities involve the exposure of people basic requirements for protecting people against to radiation from both natural and man-made undue radiation exposure in practices and inter- sources. These activities, which are planned in ventions. (See box, page 5.) IAEA BULLETIN, 2/1994 FEATURES Radiation health effects Exposure to radiation can cause detrimental health ef- impair the function of the exposed tissue. The severity of a fects. At large acute doses, radiation effects — such as particular deterministic effect is higher as doses increase nausea, reddening of the skin and, in severe cases, acute above the threshold which varies depending on the type of syndromes — are clinically expressed in exposed in- effects. The lower thresholds are a few sieverts for acute dividuals within a short period of time after exposure. Large exposures and a few hundred millisieverts per year for chronic dose rates also cause clinically detectable chronic exposures. The likelihood of incurring the deter- deleterious effects. These effects are called deterministic ministic effect, therefore, is nil at lower doses and ap- because they are certain to occur if the dose exceeds a proaches certainty at threshold doses. certain threshold level.