Radiation protection standards: a practical exercise in risk assessment

"Radiation and Risk", 1992, vol. 2, pp. 119-127


Clarke Roger H.
Director, National Radiological Protection Board Member, International Commission on Radiological Protection


Within 12 months of the discovery of x-rays in 1895, it was reported that large doses of radiation were harmful to living human tissues. The first radiation protection standards were set to avoid the early effects of acute irradiation. By the 1950s, evidence was mounting for late somatic effects - mainly a small excess of cancers - in irradiated populations. In the late 1980s, sufficient human epidemiological data had been accumulated to allow a comprehensive assessment of carcinogenic radiation risks following the delivery of moderately high doses. Workers and the public are exposed to lower doses and dose-rates than the groups from whom good data are available so that risks have had to be estimated for protection purposes. However, in the 1990s, some confirmation of these risk factors has been derived from occupationally exposed populations. If an estimate is made of the risk per unit dose, then in order to set dose limits, an unacceptable level of risk must be established for both workers and the public. There has been and continues to be a debate about the definitions of "acceptable", "unacceptable" and "tolerable" and the attributing of numerical values to these definitions. This paper discusses the issues involved in the quantification of these terms and their application to setting dose limits on risk grounds. Conclusions are drawn about the present protection standards and the application of the methods to the other fields of risk assessment.

Key words
Standardization, radiation exposure, radiation safety, radiation risk, radiation carcinogenesis, radiation dose limits, risks of professionals


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