Thierry Schneider

The classification of harmful radiation-induced effects into ‘stochastic’ and ‘deterministic’ or ‘cancer/heritable effects’ and ‘tissue reactions’ has played a significant role in the recommendations of the International Commission on Radiological Protection (ICRP) over a number of decades. More recently, however, there has been a debate regarding the adequacy of the current scheme for classification of health effects with current scientific evidence. While these scientific aspects are discussed in greater detail in a parallel article, we will emphasise the practical importance of the classification itself here. The setting of dose limits is quite different for ‘deterministic’ and ‘stochastic’ effects. In the first case, provided reliable data regarding the threshold doses for radiation effects on a particular tissue are available, the dose limit is supposed to avoid harm altogether. With ‘stochastic effects’, the expected risks at the dose limit are supposed to be ‘tolerable’. Below the dose limit, optimisation must be aimed for based on the ‘prudent’ assumption that the stochastic risks linearly depend on the dose and that there is no threshold. If the distinction between the two kinds of harmful effects is drawn into question, possible consequences for the system of radiological protection need to be considered, especially in the context of its aims as they currently apply, namely, ‘to manage and control exposures to ionising radiation so that deterministic effects are prevented, and the risks of stochastic effects are reduced to the extent reasonably achievable’. It may be necessary, moreover, to discuss if and how the terminology used by ICRP (and others), in particular the terms ‘deterministic effects’ and ‘tissue reactions’, should continue to be used for the classification of radiation effects.

In the current system of radiological protection, radiation effects are classified as either tissue reactions (also known as deterministic effects) or stochastic effects. The objectives of the system are to manage and control exposures to ionising radiation so that harmful tissue reactions are prevented, and the risks of stochastic effects are reduced to the extent reasonably achievable. Thus, the classification of health effects is a very important pillar of the system of radiological protection. In recent years, there has been debate regarding the adequacy of the current scheme for classifying health effects. Recent publications, including those from ICRP, have highlighted the need for a review of the ICRP scheme for health effects classification. This article outlines the basis for the establishment of ICRP Task Group (TG) 123 and the outlined tasks, the key sources of uncertainties for consideration, the agreed approach and timeline to tackle the above tasks, as well as the links with and dependencies on the other ongoing developments to the system being considered by the other ICRP task groups.

The context of armed conflict situations presents unique challenges that can compromise the safety and well-being of both affected populations and responders in radiological and nuclear emergencies. The focus of the EU project RRADEW “Resilience to RADiological Events in Wartime” is to enhance nuclear Emergency Preparedness, Response and Recovery (EPR&R) systems by strengthening resilience to potential incidents in the context of war or armed conflict. The project is structured in five workpackages focusing on the development of war scenarios (WP1), identification of resilience dimensions and indicators (WP2 and 3), development of decision-support, training materials and recommendations targeting key stakeholders (WP4), and key ethical questions for radiological protection in the context of armed conflicts (WP5). Together, these efforts aim to provide actionable frameworks and recommendations to ensure the safety and well-being of both affected populations and responders in wartime radiological incidents.

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.

The 16th International Congress of the International Radiation Protection Association (IRPA16), held in conjunction with the 69th Annual Meeting of the Health Physics Society (HPS) in Orlando, USA, provided an excellent platform for radiation protection professionals to exchange knowledge and advancements in radiological protection science and practice. The event featured 1241 participants from 67 countries, with 241 oral presentations and 440 posters spanning 11 thematic areas, including radiation health effects, dosimetry, medical applications, nuclear energy, and emergency preparedness. Key discussions covered updates on radiological protection systems, new findings in low-dose radiation epidemiology, and advancements in radiation measurement and dosimetry. Special focus was given to education and training, stakeholder engagement, and the integration of ethical considerations into radiological protection practices. The congress also highlighted emerging challenges in non-ionising radiation (NIR), medical radiation safety, and radioactive waste management. Notably, the prestigious Rolf M. Sievert Award was presented to Dr Maria del Rosario Perez for her significant contributions to global radiation protection, and the Gold Medal for Radiation Protection was awarded to Dr Ohtsura Niwa for his work in community engagement following the Fukushima accident. IRPA16 reinforced the importance of harmonising radiation protection standards globally and fostering interdisciplinary collaboration to address emerging scientific and societal challenges in radiological safety.

The accident at the Fukushima Daiichi Nuclear Power Station in March 2011 has left the people of the region with the task of rebuilding the lives of their families and communities, ensuring public health, and securing economic and social sustainability. The insights of the social sciences and humanities (SSH) have an important role to play in the recovery of individuals and communities affected by the accident. Sharing lessons and perspectives from the accident is essential for the recovery in Fukushima and for global future disaster preparedness. An online preparatory meeting was held on 25 May 2024 and the workshop was held on 26–27 October 2024 in a hybrid form to discuss the role of SSH in the recovery process after the Fukushima accident. After a brief presentation of the discussions held at the preparatory meeting, this article presents the main conclusions of the workshop as well as its possible future developments.

The System of Radiological Protection (the “System”) developed by the International Commission on Radiological Protection (ICRP) is built on nearly a century of efforts of numerous scientists and practitioners working together internationally. It rests on three enduring pillars: science, ethics, and experience. These pillars support the three fundamental principles that shape radiological protection strategies: justification, optimisation, and application of dose limits. Of note, optimisation of protection must be understood as a flexible and context-sensitive process, which allows identification of the appropriate level of protection, not simply the lowest dose, taking into account economic, societal and environmental factors. The System has proven effective in protecting workers, patients, members of the public, and the environment in all exposure situations. Effects of high doses, where acute injuries to healthy tissue occur, are rarely observed, and mostly due to accidental situations except for unavoidable side effects of radiotherapy. At low doses, the System is supported by application of the Linear-No-Threshold (LNT) model. This model enables prudent (that is, carefully considered given existing uncertainties) policy decisions and estimation of risks at low doses by extrapolation from epidemiological data observed at medium and high radiation doses, acknowledging uncertainty without ignoring potential harm.

A risk indicator that allows for the comparison of risks caused by different factors is highly useful for enhancing public understanding. The International Commission on Radiological Protection developed the concept of ‘detriment’ to quantify radiation-related health effects at low doses. However, the detriment is specific to the radiation field and cannot be simply compared with other risks. In this study, the disability-adjusted life years (DALYs), lifetime incidence risk, and lifetime mortality risk due to radiation exposure were compared among 33 countries. These risk indicators were calculated for all solid cancers, colon cancer, lung cancer, breast cancer, thyroid cancer, and leukaemia. The values of risk indicators for all solid cancers differed by a factor of 1.5–2.0 for male and 1.2–1.5 for female among countries, with higher values observed in countries with a higher socio-demographic index. The ratios of radiation risk indicators to the baseline indicators (R/B ratios) were 10%–15% for male and 15%–25% for female under chronic exposure to 20 mSv yr⁻¹ radiation from the age of 18 to 64 years, and 1.0%–1.5% for male and 1.5%–2.5% for female under chronic exposure to 1 mSv yr⁻¹ radiation over a lifetime. In particular, the R/B ratios under chronic exposure to 1 mSv yr⁻¹ radiation were smaller than the variation in the baseline risk indicators across countries. The impact of different countries and stages of disability weight of DALYs was small. Note that estimates of DALYs for less lethal thyroid cancers were subject to greater uncertainty. This study indicated that DALYs should be noted as an alternative indicator to the radiation detriments when discussing the tolerability of radiation and communicating with the society.

This study examined how discharged ALPS-treated water (DTW), social capital (SC), health-related quality of life (HR-QOL), and radiation risk perception influence residents’ intention to return (ITR) to the affected areas around TEPCO Fukushima Daiichi Nuclear Power Station (FDNPS), within a 20 km radius. The concerns about DTW were investigated six months before authorities began discharging treated water into the Pacific Ocean, in August 2023. It was revealed that residents who wanted to return were mostly concerned about the DTW (p < 0.05). Compared to the residents who had already returned, the community trust and attachment was lower in non-returnees (p < 0.01). Residents of areas affected by the FDNPS accident remain concerned about various issues regarding radiation. These results provide important suggestions for how to provide appropriate support that addresses the specific concerns of former residents of affected areas.

Un atelier sur l’avenir de la radioprotection a été organisé conjointement par l’Institut de radioprotection et de sûreté nucléaire (IRSN), le Centre d’étude sur l’évaluation de la protection dans le domaine nucléaire (CEPN) et la Commission internationale de protection radiologique (CIPR) en mars 2024. L’objectif était de présenter les développements récents au sein de la CIPR et d’échanger avec les représentants de la communauté française de la radioprotection sur l’examen et la révision du Système de protection radiologique. Cet article présente une synthèse des principaux points de discussion abordés durant cet atelier.