Emerging challenges for the international system of radiation protection quantities and units

This paper submitts a diagnosis of potential difficulties with the international system of radiation protection quantities and units and describe potential successes and challenges for addressing possible difficulties with the system. It summarizes critiques to the system, including lessons compiled in the aftermath of the Fukushima accident and reflections from professionals in metrology. It also addresses the reaction of ICRP and ICRU for addressing those challenges. It suggests that the proposed revisions, while welcomed, could be insufficient. The system seems to present some epistemological challenges that need to be addressed. They include that a common quantity and unit are used for: distinct outcomes, such as clinically observable, or statistically observable or biologically plausible radiation effects; different concepts, such as that at high doses, effects are attributed and at low doses risk are inferred; diverse outputs, such as diagnosis of individual effect, estimates of collective incidences, or judgment of risk; attesting on health outcomes trough formal evidence by radiopathologists, or radioepidemiologists or radioprotectionists; and, for imputing individual harm or collective harm (class actions) or presumptions of risk. Moreover, the same family of dosimetric quantities (without any provisos) are used as: intensive quantities, and extensive quantities. This does not happen in other areas of science requiring measurability. Finally, an important shortcoming of the current system is addressed: the current quantities and units seems to be unhelpful for public information and communication; they should fail to convey, in a fully and easily understandable and credible manner, radiation effects and risks therefore facilitating psychological associated to the misunderstanding of radiation. It is concluded that the relevant international and intergovernmental organizations should consider improving the current international system of quantities and units not only in its obvious shortcomings but also in its epistemological deficiencies and its communicational weaknesses. (authors)