Why Low-level Radiation Exposure Should Not Be Feared.

ABSTRACT: The purpose of this paper is to address the public fear that is usually associated with low-level radiation exposure situations. Its ultimate objective is to provide persuasive assurances to informed but skeptical members of the public that exposure situations involving low-level radiation are not to be feared. Unfortunately, just acquiescing to an unsupportive public fear of low-level radiation is not without consequences. It is causing severe disruptions to the benefits that harnessed radiation can produce for the well-being of all humanity. In this pursuit, the paper provides the scientific and epistemological basis needed for regulatory reform by reviewing the history in quantifying, understanding, modeling, and controlling radiation exposure, including some of the evolving contributions of the United Nations Scientific Committee on the Effects of Atomic Radiation, the International Commission on Radiological Protection, and the myriad of international and intergovernmental organizations establishing radiation safety standards. It also explores the various interpretations of the linear no-threshold model and the insights gained from radiation pathologists, radiation epidemiologists, radiation biologists, and radiation protectionists. Given that the linear no-threshold model is so deeply imbedded in current radiation exposure guidance, despite the lack of a solid scientific base on the actually proven radiation effects at low-doses, the paper suggests near-term ways to improve regulatory implementation and better serve the public by excluding and/or exempting trivial low-dose situations from the regulatory scope. Several examples are given where the unsubstantiated public fear of low-level radiation has resulted in crippling the beneficial effects that controlled radiation offers to a modern society.

Radiological protection issues arising during and after the Fukushima nuclear reactor accident.

Following the Fukushima accident, the International Commission on Radiological Protection (ICRP) convened a task group to compile lessons learned from the nuclear reactor accident at the Fukushima Daiichi nuclear power plant in Japan, with respect to the ICRP system of radiological protection. In this memorandum the members of the task group express their personal views on issues arising during and after the accident, without explicit endorsement of or approval by the ICRP. While the affected people were largely protected against radiation exposure and no one incurred a lethal dose of radiation (or a dose sufficiently large to cause radiation sickness), many radiological protection questions were raised. The following issues were identified: inferring radiation risks (and the misunderstanding of nominal risk coefficients); attributing radiation effects from low dose exposures; quantifying radiation exposure; assessing the importance of internal exposures; managing emergency crises; protecting rescuers and volunteers; responding with medical aid; justifying necessary but disruptive protective actions; transiting from an emergency to an existing situation; rehabilitating evacuated areas; restricting individual doses of members of the public; caring for infants and children; categorising public exposures due to an accident; considering pregnant women and their foetuses and embryos; monitoring public protection; dealing with 'contamination' of territories, rubble and residues and consumer products; recognising the importance of psychological consequences; and fostering the sharing of information. Relevant ICRP Recommendations were scrutinised, lessons were collected and suggestions were compiled. It was concluded that the radiological protection community has an ethical duty to learn from the lessons of Fukushima and resolve any identified challenges. Before another large accident occurs, it should be ensured that inter alia: radiation risk coefficients of potential health effects are properly interpreted; the limitations of epidemiological studies for attributing radiation effects following low exposures are understood; any confusion on protection quantities and units is resolved; the potential hazard from the intake of radionuclides into the body is elucidated; rescuers and volunteers are protected with an ad hoc system; clear recommendations on crisis management and medical care and on recovery and rehabilitation are available; recommendations on public protection levels (including infant, children and pregnant women and their expected offspring) and associated issues are consistent and understandable; updated recommendations on public monitoring policy are available; acceptable (or tolerable) 'contamination' levels are clearly stated and defined; strategies for mitigating the serious psychological consequences arising from radiological accidents are sought; and, last but not least, failures in fostering information sharing on radiological protection policy after an accident need to be addressed with recommendations to minimise such lapses in communication.

International policies and strategies for the remediation of land contaminated by radioactive material residues.

The paper addresses the international policies and strategies for the remediation of land contaminated by radioactive material residue, its main aim being to describe the misunderstandings, evolution and status of the international paradigms in this area. Thus, the denotation and connotation of the 'remediation' and 'contamination' concepts are explored, including the ambiguity they produce in understanding of the issues by a sceptical public. Then, the international radiation protection approaches for remediation are portrayed. They derive from the recommendations of the International Commission on Radiological Protection (ICRP), which are described including their basic principles and characterization of exposure situations. Prolonged exposure situations, which are typical in cases of contaminated land, are analysed with particular detail. The newer ICRP general recommendations, as well as recent ICRP recommendations for excluding and exempting exposure situations from regulatory control and for living in long-term contaminated territories after a nuclear accident or a radiation emergency, are examined. Remediation vis-à-vis environmental protection is discussed and the non-technical factors usually involved in decision-making on remediation are examined. Finally, the international safety standards on remediation, which are being established under the aegis of the International Atomic Energy Agency (IAEA), are explored. These include the well established International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, or BSS, as well as the specific international safety requirements for remediation; a brief overview of the current process of revising the BSS is also included. In its outcome the paper suggests that the time is ripe for a simple and clear international agreement on the levels of radioactivity in territorial contamination with radioactive material that may be considered unambiguously safe.

The recommendations of the ICRP vis-à-vis the Fukushima Dai-ichi NPP accident aftermath.

The International Commission on Radiological Protection (ICRP) created a Task Group (ICRP TG84) on the initial lessons learned from the nuclear accident at the Fukushima Dai-ichi NPPs vis-à-vis the ICRP system of radiological protection. The ICRP TG84 is expected to compile lessons learned related to the efforts carried out to protect people against radiation exposure during and after the emergency exposure situation caused by the accident and, in light of these lessons, to consider ad hoc recommendations to strengthen the ICRP system of radiological protection for dealing with this type of emergency exposure. The Chairman of ICRP TG84 presents in this paper his personal views on the main issues being considered by the group at the time of the Fukushima Expert Symposium. ICRP TG84 expects to finalize its work by the end of 2012.

Cytogenetic damage in cells exposed to ionizing radiation under conditions of a changing dose rate.

The current international paradigm on the biological effects of radiation is based mainly on the effects of dose with some consideration for the dose rate. No allowance has been made for the potential influence of a changing dose rate (second derivative of dose), and the biological effects of exposing cells to changing dose rates have never been analyzed. This paper provides evidence that radiation effects in cells may depend on temporal changes in the dose rate. In these experiments, cells were moved toward or away from an X-ray source. The speed of movement, the time of irradiation, and the temperature during exposure were controlled. Here we report the results of the first experiments with TK6 cells that were exposed at a constant dose rate, at an increasing dose rate, or at a decreasing dose rate. The average dose rate and the total dose were same for all samples. Micronuclei were scored as the end point. The results show that the level of cytogenetic damage was higher in cells exposed to a decreasing dose rate compared to both an increasing and a constant dose rate. This finding may suggest that the second derivative of dose may influence radiation risk estimates, and the results should trigger further studies on this issue.

Chernobyl vis-à-vis the nuclear future: an international perspective.

The paper aims to provide an international perspective on the consequences of the Chernobyl accident vis-à-vis the future development of the use of nuclear energy for peaceful purposes. It describes the major international initiatives that were undertaken over the years in order to quantify the consequences of the Chernobyl accident, and also analyzes the impact of the accident on the development of nuclear energy taking account of the perception of its consequences. The paper revisits the historical saga flowing since the fateful explosion at the Chernobyl Nuclear Power Plant in the Ukraine 20 y ago. It looks at some of the misunderstandings about the consequences of the accident and explores the worldwide nuclear stagnation that followed Chernobyl, surveying the negative public reaction and also the possibilities of a nuclear revival. It finally searches for a way forward, concluding that an effective international nuclear safety regime is urgently needed with the purpose of preventing catastrophes like Chernobyl from occurring and also that the Chernobyl consequences need to be readdressed properly. The paper concludes with an appeal to the radiation protection community to resolve once and for all the difficult issues of attributing health effects to low-level radiation exposure.

Scope of radiological protection control measures.

In this report, the Commission recommends approaches to national authorities for their definition of the scope of radiological protection control measures through regulations, by using its principles of justification and optimisation. The report provides advice for deciding the radiation exposure situations that should be covered by the relevant regulations because their regulatory control can be justified, and, conversely, those that may be considered for exclusion from the regulations because their regulatory control is deemed to be unamenable and unjustified. It also provides advice on the situations resulting from regulated circumstances but which may be considered by regulators for exemption from complying with specific requirements because the application of these requirements is unwarranted and exemption is the optimum option. Thus, the report describes exclusion criteria for defining the scope of radiological protection regulations, exemption criteria for planned exposure situations, and the application of these concepts in emergency exposure situations and in existing exposure situations. The report also addresses specific exposure situations such as exposure to low-energy or low-intensity adventitious radiation, cosmic radiation, naturally occurring radioactive materials, radon, commodities, and low-level radioactive waste. The quantitative criteria in the report are intended only as generic suggestions to regulators for defining the regulatory scope, in the understanding that the definitive boundaries for establishing the situations that can be or need to be regulated will depend on national approaches.

Lauriston S. Taylor Lecture: Radiation protection in the aftermath of a terrorist attack involving exposure to ionizing radiation.

I would like to start this Twenty-Eighth Lauriston S. Taylor Lecture by expressing my gratitude to the National Council on Radiation Protection and Measurements (NCRP) for this unique occasion. I feel particularly honored for this opportunity to address a highly specialized and qualified audience of professionals who are specifically interested in what appears to be a forthcoming worldwide challenge, namely radiological terrorism and managing its potential radiological consequences.

Radiation safety standards and their application: international policies and current issues.

This paper briefly describes the current policies of the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection and how these policies are converted into international radiation safety standards by the International Atomic Energy Agency, which is the only global organization-within the United Nations family of international agencies-with a statutory mandate not only to establish such standards but also to provide for their application. It also summarizes the current status of the established corpus of such international standards, and of it foreseeable evolution, as well as of legally binding undertakings by countries around the world that are linked to these standards. Moreover, this paper also reviews some major current global issues related to the application of international standards, including the following: strengthening of national infrastructures for radiation safety, including technical cooperation programs for assisting developing countries; occupational radiation safety challenges, including the protection of pregnant workers and their unborn children, dealing with working environments with high natural radiation levels, and occupational attributability of health effects (probability of occupational causation); restricting discharges of radioactive substances into the environment: reviewing current international policies vis-a-vis the growing concern on the radiation protection of the "environment;" radiological protection of patients undergoing radiodiagnostic and radiotherapeutic procedures: the current International Action Plan; safety and security of radiation sources: post-11 September developments; preparedness and response to radiation emergencies: enhancing the international network; safe transport of radioactive materials: new apprehensions; safety of radioactive waste management: concerns and connections with radiation protection; and radioactive residues remaining after the termination of activities: radiation protection response to the forthcoming wave of decommissioning of installations with radioactive materials. The ultimate aim of this paper is to encourage information exchange, cooperation, and collaboration within the radiation protection professional community. In particular, the paper tries to facilitate consolidation of the growing international regime on radiation safety, including the expansion of legally binding undertakings by countries, the strengthening of the current corpus of international radiation safety standards, and the development of international provisions for ensuring the proper worldwide application of these standards, such as a system of international appraisals by peer review.