Revisiting Tolerability and Reasonableness in the System of Radiological Protection.

The concepts of risk tolerability and the search for reasonableness are central to the implementation of the International Commission on Radiological Protection (ICRP) system of radiological protection. For a given exposure situation, it is necessary to ask whether the doses received (or potentially received) by those exposed can be considered tolerable with regard to the radiation-induced risk (consistent with the principle of application of dose limits). In addition, it should be assessed whether all exposures are maintained or reduced as low as reasonably achievable taking into account economic, societal, and environmental factors (consistent with the principle of optimization of protection). Relying on the ethical foundations of the ICRP system (i.e., Publication 138), ICRP Task Group 114 (TG114) is engaged in a critical reflection on the history, definitions, roles, scope, and application of "tolerability" and "reasonableness" in the context of radiological protection. In developing and articulating a revised framework for tolerability and reasonableness, focusing on the achieved level of protection and the concept of well-being, consideration has been given to application of this framework in different contexts. This paper provides a brief overview of the motivation and current work of TG114 and highlights key points for the application of the proposed revised framework in three contexts: i.e., medicine, emergency and recovery after a nuclear accident, and the nuclear sector.