Collective dose. IRSN view on its indications and contraindications

S. Supervil (travail collectif), European IRPA congress, octobre 2002, Rapport IRSN/DES/536

The concept of collective protection appeared in 1959 in the first report of the International Commission on Radiological Protection (ICRP). During the course of the next decades, ICRP gave details on the use of the collective dose, in particular on its role in the process of optimisation of protection. In 1991, ICRP outlined that the collective dose takes account of the number of people exposed to a source by multiplying the average dose to the exposed group by the number of individuals in the group. At present, the collective dose is currently used by those who practice radiological protection, in a prospective and retrospective way. Its use with respect to the management of the protection of workers scarcely raises any debates. On the other hand, its use to assess the public exposure or to estimate the health effects of exposure to ionizing radiation (workers or population) raises numerous criticisms. Some of these criticisms, relating to ethical nature, underline that the collective does not reflect the inequities among the exposed individuals. Criticisms, scientific in nature, concern the linear-nonthreshold dose effect relationship hypothesis, which enables the collective dose to be represented in terms of risk of the occurrence of stochastic effects. Other criticisms, of an operational nature, relate to the feasibility and the reliability of some collective dose calculations. The former Institut de Protection et de Sûreté Nucléaire (IPSN), being aware of the problems raised by the use of the collective dose, formulated an opinion on this question, which formed the subject of a publication within the set of « Documents IPSN », in December 2001. Institut de Radioprotection et de Sûreté Nucléaire (IRSN), which was created in February 2002, take up the this publication. It is devoted to radiological protection practitioners, whatever their level of responsibility is (operators, employers, authorities).