ICRP Publication 124: Protection of the Environment under Different Exposure Situations.

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A DECADE ON RADIOLOGICAL PROTECTION OF THE ENVIRONMENT Diego M. Telleria, R.J. Pentreath, Carol A. Robinson, Christopher H. Clement, J. Lochard, C-M. Larsson, D.A. Cool, P. Strand, J. Simmonds, D. Copplestone, D. Oughton and E. Lazo Ann ICRP 2014 43: 1 DOI: 10.1177/0146645313497456 The online version of this article can be found at: http://ani.sagepub.com/content/43/1/1

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International Commission on Radiological Protection

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Annals of the ICRP ICRP PUBLICATION 124

Protection of the Environment under Different Exposure Situations Editor-in-Chief C.H. CLEMENT Associate Editor M. SASAKI Authors on behalf of ICRP R.J. Pentreath, J. Lochard, C-M. Larsson, D.A. Cool, P. Strand, J. Simmonds, D. Copplestone, D. Oughton, E. Lazo

PUBLISHED FOR The International Commission on Radiological Protection by

Please cite this issue as ‘ICRP, 2014. Protection of the environment under different exposure situations. ICRP Publication 124, Ann. ICRP 43(1).’

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CONTENTS EDITORIAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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GLOSSARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2. Objectives and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

23 23

2. THE COMMISSION’S FRAMEWORK FOR PROTECTION OF THE ENVIRONMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

25

2.1. 2.2. 2.3. 2.4.

Objectives of protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reference Animals and Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Derived Consideration Reference Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Exposure pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

25 26 27 28

3. APPLICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3.1. Types of exposure situations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Principles of protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3. Reference values for environmental protection based on Derived Consideration Reference Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

29 29

4. IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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4.1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Selecting representative organisms and their relationships to Reference Animals and Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Additional considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. Stakeholder involvement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

35 35 39 40

5. COMPLIANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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6. DISCUSSION AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

45

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31

REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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APPENDIX A: TABLES OF DOSE RATES AND EFFECTS FOR REFERENCE ANIMALS AND PLANTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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APPENDIX B: ASSUMED BASIC POPULATION CHARACTERISTICS OF REFERENCE ANIMALS AND PLANTS . . . . . . .

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ANNEX C: ENVIRONMENTAL PROTECTION LEGISLATION. . . . . . . . . .

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ICRP Publication 124

Editorial A DECADE ON RADIOLOGICAL PROTECTION OF THE ENVIRONMENT It is somehow fitting that this report should be published as we approach the 10th anniversary of Publication 91 (ICRP, 2003), the International Commission on Radiological Protection’s (ICRP) first publication on protection of the environment. It also marks 10 years since the International Conference on the Protection of the Environment from the Effects of Ionizing Radiation, held in Stockholm in 2003. The primary objective of the Stockholm conference was to promote the development of a coherent international policy on the protection of the environment from effects attributable to ionising radiation. It is worth briefly revisiting the findings of the Stockholm conference to fully appreciate how far we have travelled over the last decade. The main finding of the conference was that time is ripe for launching a number of international initiatives to consolidate the present approach to controlling radioactive discharges to the environment, taking explicit account of the protection of species other than humans (IAEA, 2003). In specifying this, the international community gathered in Stockholm set expectations on a number of international organisations, including ICRP, as follows: 1. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) should continue to provide findings on the sources and effects of ionising radiation that can be used as the authoritative scientific basis for future international efforts in environmental radiation protection. 2. ICRP should continue to issue recommendations on radiation protection, including specific recommendations for the protection of non-human species. 3. The International Atomic Energy Agency (IAEA) should establish appropriate international undertakings, including international standards and mechanisms for their worldwide application, to restrict releases of radioactive materials into the environment over time, in order that not only humans but also the non-human component of the environment is protected adequately. IAEA should continue to foster information exchange by organising international meetings on this subject. In the intervening period, UNSCEAR has published an annex on the effects of ionising radiation on non-human biota (United Nations, 2008); ICRP has published a series of reports that will be mentioned in more detail below; and IAEA, with other international organisations, has revised the International Basic Safety Standards that 5



define requirements to satisfy the fundamental safety objective of protecting people and the environment from harmful effects of ionising radiation (IAEA, 2011). Other efforts at national and international level also nurtured the process of development of a system for environmental protection, notably the work promoted by the International Union of Radioecology (IUR, 2012). The European Commission’s initiatives FASSET (Larsson, 2004) and ERICA (Larsson, 2008), and the US Department of Energy’s Biota Dose Assessment Committee (US Department of Energy, 2002) also provided significant contributions. In 2003, the system of radiological protection, as it related to the environment, was entirely dependent on the belief that the standards of environmental control needed to protect humans to the degree currently thought desirable will ensure that other species are not put at risk (ICRP, 1991). In Publication 91 (ICRP, 2003), ICRP acknowledged that this system provided indirect protection of the human habitat, but that a more comprehensive approach to study the effects on, and thus the protection of, all living matter with respect to ionising radiation should be developed. This publication further identified the principles of environmental protection, and proposed a framework for assessing the impacts of ionising radiation on non-human species, based on a reference flora and fauna approach. The 2007 Recommendations of ICRP (ICRP, 2007) effectively extended the system of protection to address protection of the environment, including flora and fauna, more explicitly. These recommendations explore the objectives of environmental protection and explain the basis for the proposed Reference Animals and Plants (RAPs), which are a small set of hypothetical entities that are representative of animals and plants present in different environments (terrestrial, freshwater, marine) and which form the basis of a structured approach to the assessment of exposures to, and effects of, ionising radiation. The concept and use of RAPs was dealt with in more detail in Publication 108 (ICRP, 2008), which contains information on the assumed biology, dosimetry, and available effects database for these entities. A range of Derived Consideration Reference Levels (DCRLs) were also proposed for each of the RAPs as numerical guidance for evaluating the level of potential or actual radiological impacts and as an input to decision making. These values were defined in terms of bands of doses within which certain effects have been noted, with a focus on those which may have some impact on the population structures of the animals and plants under consideration. In 2009, Publication 114 was issued (ICRP, 2009), providing transfer parameters for the set of RAPs. The present report, which results from a joint effort of ICRP Committees 4 and 5, consolidates the suite of ICRP recommendations on environmental protection and provides further guidance on their application. It places the assessment of potential impacts on animals and plants within the existing system of radiological protection. In particular, it provides a mechanism for allowing environmental considerations to be 6


Protection of the environment under different exposure situations

included in the identification of the best management options, as part of the optimisation process. At the planning stage, the approach will allow practical environmental considerations to be part of decisions about minimising the possibility of potential exposures. During normal operations, the approach will allow explicit demonstration of the level of radiological protection of flora and fauna, as part of the process of routine assessment and surveillance. The approach will also allow impacts on animals and plants to be assessed and managed in a more informed manner in seeking solutions to existing exposures as a result of past practices or accidents. Finally, it will allow the significance of the impact of a severe emergency situation on animals and plants to be assessed where appropriate. Thus, this approach allows protection of the environment to be considered in a more explicit manner in all the exposure situations, and provides an objective basis for better management of environmental resources. It is worth noting that, although this report represents a significant milestone in the development of an approach for environmental radiation protection, its publication does not represent the end of the story. The ICRP framework and its application are open to future inputs from the scientific community. Indeed, ICRP recognises that protection of the environment is a complex issue and that its framework cannot be expected to solve all relevant issues immediately; after all, it has taken almost 40 years for the system of radiological protection for humans to reach its current state of development. It is anticipated that this approach will serve to provide a mechanism to inspire future scientific activities and to help define priorities. Its strength is that it can serve as a starting point to assess and manage the radiological impact on non-human species, and as a concrete reference against which to analyse the need for expansion or alternative solutions to the concept of RAPs in the future. In developing its framework, ICRP has successfully navigated a difficult course between a range of external and internal expectations and drivers. The external situation has been tempered by the markedly different opinions among members of the radiological protection community, particularly in the early stages. Many argued that no change in the existing system of radiological protection was necessary given that humans and the environment were already adequately protected by current safety levels, and that the existing hypothesis has been confirmed by numerous studies in the context of normal exposures. The main driver for change has been the increasing awareness in society, since the 1990s, of the need for equitable consideration of economic development and environmental protection, which has been reflected in the establishment of formal international and national legal instruments related to, for example, conservation, sustainability, and biodiversity. In light of this, ICRP has responded to growing international consensus that, for certain situations, methods that allow explicit evaluation of the potential impact of releases of radioactivity to the environment are a necessary input to decision making. In undertaking this work, ICRP also specified a number of internal conditions that are worthy of note. It determined that complexity of the framework for protection of 7



the environment, including the assessment of impacts on flora and fauna, should be commensurate with the level of risk, such that its application would facilitate the best use of appropriate resources and avoid the expenditure of unnecessary effort. ICRP also specified that the approach should be compatible with both the existing system of radiological protection and current methods for assessing the effects of other environmental stressors. Finally, ICRP set out to develop a method that was based on best use of the current level of scientific knowledge, while allowing the new information to be collected and incorporated into the approach in the future. At the end of an eventful decade, with the publication of the present report, organisations with the mandate to develop further international and national standards have the basis for developing practical guidance and standards that allow the environment to be considered in a more explicit manner that ultimately reinforce the system of radiological protection. On a completely different subject, this issue of Annals of the ICRP is the first to be published by SAGE UK. From 1928 to 1959, ICRP reports, including those under ICRP’s former name – International X-ray and Radium Protection Committee – were published as articles or on behalf of ICRP by other organisations. What later became known as Publication 1 (ICRP, 1959) was the first volume issued by ICRP, published as a book by Pergamon Press. Eventually, ICRP moved to a journal format, producing Publication 24 as Volume 1, Issue 1 of Annals of the ICRP in 1977 (ICRP, 1977). In 2004, Pergamon Press was acquired by Elsevier, who continued to publish Annals of the ICRP for many years, up to and including Publication 123 (ICRP, 2013). The move from Elsevier to SAGE was the result of a competitive process, and has been almost seamless thanks to the professionalism of both companies. It seems more like a move to SAGE than a move from Elsevier, with whom we continue to have very good relations. Examining the current issue, readers will see that we have not made any major changes in format to coincide with this change in publisher, and none are planned. It may be possible to detect a few minor style changes, but these are evolutionary improvements not unlike other small changes that have occurred over the last few years. ICRP looks forward to this new partnership with SAGE, together finding new and exciting ways to make it even easier for those with an interest in radiological protection to access the guidance and recommendations of ICRP. DIEGO M. TELLERIA CAROL A. ROBINSON CHRISTOPHER H. CLEMENT ICRP SCIENTIFIC SECRETARY EDITOR-IN-CHIEF

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REFERENCES US Department of Energy, 2002. A graded approach for evaluating radiation doses to aquatic and terrestrial biota, DOE Standard, DOE-STD-1153-2002, US Department of Energy, Washington DC. IAEA, 2003. International Conference on the Protection of the Environment from the Effects of Ionizing Radiation, 6 – 11 October 2003, Presidents’s Findings, Available at: (last accessed 13 November 2013). IAEA, 2011, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards Interim Edition, General Safety Requirements Part 3 No. GSR Part 3 (Interim), International Atomic Energy Agency, Vienna, Austria. ICRP, 1959. Recommendations of the International Commission on Radiological Protection. Now known as ICRP Publication 1, Pergamon Press, London, UK. ICRP, 1977. Radiation protection in uranium and other mines. ICRP Publication 24, Ann. ICRP 1(1). ICRP, 1991. 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann. ICRP 21 (1–3). ICRP, 2003. A framework for assessing the impact of ionising radiation on non-human species. ICRP Publication 91. Ann. ICRP 33(3). ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological Protection, ICRP Publication 103. Ann. ICRP 37(2–4). ICRP, 2008. Environmental protection: the concept and use of Reference Animals and Plants. ICRP Publication 108. Ann ICRP 38(4–6). ICRP, 2009. Environmental protection: transfer parameters for Reference Animals and Plants. ICRP Publication 114. Ann ICRP 39(6). ICRP, 2013. Assessment of Radiation Exposure of Astronauts in Space. ICRP Publication 123. Ann ICRP 42(4). IUR, 2012. Towards an ecosystem approach for protection with emphasis on radiological hazards. IUR Report 7, 2nd Edition, Cadarache, France. Larsson, C-M., 2004. The FASSET framework for assessment of environmental impact of ionizing radiation in European ecosystems – an overview. J. Radiol. Prot. 24, A1–A12. Larsson, C-M., 2008. An overview of the ERICA integrated approach to the assessment and management of environmental risks from ionizing contaminants. J. Environ. Radioact. 99, 1364–1370. United Nations, 2008. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2008 Report, Sources and effects of ionising radiation, Vol ll. Annex E. Effects of ionizing radiation on non-human biota. United Nations, New York.

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Protection of the Environment under Different Exposure Situations ICRP PUBLICATION 124 Approved by the Commission in April 2013

Abstract—In this report, the Commission describes its framework for protection of the environment and how it should be applied within the Commission’s system of protection. The report expands upon its objectives in relation to protection of the environment, in so far as it relates to the protection of animals and plants (biota) in their natural environment, and how these can be met by the use of Reference Animals and Plants (RAPs); their Derived Consideration Reference Levels (DCRLs), which relate radiation effects to doses over and above their normal local background natural radiation levels; and different potential pathways of exposure. The report explains the different types of exposure situations to which its recommendations apply; the key principles that are relevant to protection of the environment; and hence how reference values based on the use of DCRLs can be used to inform on the appropriate level of effort relevant to different exposure situations. Further recommendations are made with regard to how the Commission’s recommendations can be implemented to satisfy different forms of environmental protection objectives, which may require the use of representative organisms specific to a site, and how these may be compared with the reference values. Additional information is also given with regard to, in particular, communication with other interested parties and stakeholders. Issues that may arise in relation to compliance are also discussed, and the final chapter discusses the overall implications of the Commission’s work in this area to date. Appendices A and B provide some numerical information relating to the RAPs. Annex C considers various existing types of environmental protection legislation currently in place in relation to large industrial sites and practices, and

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the various ways in which wildlife are protected from various threats arising from such sites. ß 2014 ICRP. Published by SAGE. Keywords: Radiation; Exposure situations; Environmental protection; Biota AUTHORS ON BEHALF OF ICRP

R.J. PENTREATH, J. LOCHARD, C-M. LARSSON, D.A. COOL, P. STRAND, J. SIMMONDS, D. COPPLESTONE, D. OUGHTON, E. LAZO

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PREFACE At its meeting in Suzhou, China in 2010, the Main Commission approved the formation of a new Task Group reporting to Committees 4 and 5 on ICRP’s approach to protection of the environment. This was undertaken because, although Publication 103 (ICRP, 2007) had introduced a new environmental protection requirement into its recommendations [following on from Publication 91 (ICRP, 2003)], Publication 108 (ICRP, 2008) had made it necessary to demonstrate, explicitly, how the expanded ICRP framework held together collectively in a coherent manner. This was essential in order to articulate how more practical advice could be accommodated in the future within existing and anticipated regulatory frameworks. It was also recognised that although Publications 91 and 108 (ICRP, 2003, 2008) had collectively set out the ethics, values, and current science base underlying the Commission’s environmental objectives, it was still necessary to explain how these new areas resided within the long-standing context of the Commission’s principles of justification, optimisation, and the application of limits. The membership of the Task Group was as follows: R.J. Pentreath (Chair) D. Copplestone J. Lochard (Vice-Chair) C-M. Larsson D.A. Cool J. Simmonds

P. Strand M. Watanabe

The corresponding members were: A. Janssens D. Oughton E. Lazo I. Outola

G. Pro¨hl

D. Telleria was invited as an observer. The Task Group met twice, on 12–13 June 2010 at STUK, Helsinki, Finland, and on 28–29 June 2011 at CEPN, Fontenay-aux-Roses, France, but worked mainly by correspondence. The explanation of how the Commission’s approach to environmental protection relates to that of human radiation protection, and how the principles of justification, optimisation of protection, and application of limits apply to different exposure situations received the full endorsement of Committees 4 and 5 in Washington, USA in October 2011. Following public consultation, a small editing group met in Chilton, UK on 23–24 January 2013. The membership of Committee R.J. Pentreath (Chair) C-M. Larsson (Vice-Chair) F. Brechignac

5 during the preparation of the report was: D. Copplestone P. Strand K.A. Higley A. Real K. Sakai A. Ulanovski

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The membership of Committee J. Lochard (Chair) W. Weiss (Vice-Chair) P.A. Burns D.A. Cool T. Homma M.Kai

4 during the preparation of the report was: J.F. Lecomte G. Massera H. Liu K. Mrabit S. Liu S. Shinkarev A. McGarry J. Simmonds S.M. Magnusson A.S. Tsela P. Martinez W. Zeller

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EXECUTIVE SUMMARY (a) Within the Commission’s overall framework for protection against ionising radiation, the Commission has now broadened its scope by introducing a new requirement, that of protecting the environment. The present report describes the Commission’s framework for protection of the environment and how it should be applied within the Commission’s system of protection. (b) The Commission’s aims in terms of environmental protection are to prevent or reduce the frequency of deleterious radiation effects on biota to a level where they would have a negligible impact on the maintenance of biological diversity; the conservation of species; or the health and status of natural habitats, communities, and ecosystems. The biological endpoints of most relevance are therefore those that could lead to changes in population size or structure. Due to the immense variety of biota, and their presumed response to radiation, any credible system needs to have some key points of reference that provide some form of auditable trail that links the basic elements of the framework together, or at least could do so if further data were forthcoming and it is feasible to obtain such data. The Commission therefore developed a small set of 12 Reference Animals and Plants (RAPs), plus their relevant databases, for a few types of organisms that are typical of the major environments. The RAPs were described to the generality of the taxonomic level of Family, because this is the highest taxonomic level at which the biological features of an animal or plant of relevance to the effects of radiation can be assumed to be relatively constant. They are essentially reference models. (c) Derived Consideration Reference Levels (DCRLs) that are specific to each of the different types of RAPs have also been defined. A DCRL can be considered as a band of dose rate, spanning one order of magnitude, within which there is some chance of deleterious effects from ionising radiation occurring to individuals of that type of RAP. Thus, when considered together with other relevant information, DCRLs can be used as points of reference to inform on the appropriate level of effort that should be expended on environmental protection, dependent on the overall management objectives, the exposure situation, the actual fauna and flora present, and the numbers of individuals thus exposed. (d) The Commission therefore recommends that DCRLs should be used under all circumstances where there is, or may be, an incremental environmental exposure of significance above the natural background locally experienced by the relevant biota. In planned exposure situations, the lower boundary of the relevant DCRL band should be used as the appropriate reference point for protection of different types of biota within a given area during the planning of controls to a source. Due to the possibility of multiple sources affecting the same biota, or for any residual exposures arising from previous sources, consideration also needs to be given to possible cumulative impacts. (e) For existing exposure situations, and in emergency exposure situations where control of the source has not been obtained, if the dose rates are above the relevant DCRL band, the Commission recommends that the aim should be to reduce 15



exposures to levels that are within the DCRL bands for the relevant populations, with full consideration of the radiological and non-radiological consequences of so doing. If dose rates are within the bands, the Commission believes that consideration should be given to reduce exposures, assuming that the costs and benefits are such that further efforts are warranted. Thus, in the case of existing exposure situations, the DCRLs should be used as the criteria for mitigating environmental exposures. (f) As the RAPs are, by definition, points of reference, it may also be necessary to identify representative organisms relevant to each situation. These may be extremely similar to RAPs or may be different. In some cases, there will be little choice in selection because this may have been undertaken previously by way of other existing legislation. Nevertheless, differences between such biota and the RAPs should be quantifiable in relation to their basic biology, dosimetry, or radiation effects, and such differences need to be noted and taken into account. The extent to which such factors need to be applied, and their relevant impact on the final decision, will depend on the nature of the implementation and application of the planning process relevant to protection of the environment. As other regulatory bodies are likely to be involved, such as those responsible for wildlife management, it is essential to have a clearly set out logical link between any radioactive releases and potential risk of biological effects (for which the RAP framework should be a starting point), and a clearly laid out strategy by which the relevant stakeholders can be engaged in the decision-making process. (g) With regard to responding to an actual emergency event, or accidental release of radionuclides into the environment, consideration of environmental protection may not be an immediate priority, depending on the extent to which human exposures, or human food chains, are likely to be affected. However, even where human exposure concerns predominate, consideration should be given to the environmental consequences of the possible options available to achieve the adequate level of human protection. (h) After the occurrence of an accident, the framework of the DCRLs, and the set of indicative population impacts relative to the doses they receive, may be useful in communicating the implications of the situation to stakeholders, particularly in relation to environmental conditions where humans have been removed from the area, and food chains leading to human exposure have been severed. The concept of such severe-effect reference levels is often used within the chemical industry. The Commission notes that this type of level could be considered to be approximately equivalent to a band of doses two orders of magnitude above the DCRL band. With the passage of time immediately following an accidental release, information can be conveyed to the public in terms of an assessment of the environmental situation relative to a predetermined reference point, and thus the results of mitigation actions, or simply the effect of natural events, can be readily assessed and evaluated. (i) Wherever possible, protection of the environment from a source should complement controls to protect the public, and not add unnecessarily to its complexity. The Commission therefore believes that, having essentially clarified the basis upon which decisions relating to protection of the environment can be made by way of a 16



framework relating exposure to dose, and dose to effect, for different types of organisms (the set of RAPs), the demonstration of protection of both humans and nonhuman species as a result of normal planned exposure situations could well be integrated in a relatively simple manner, based solely on estimations (at the design stage) and measurements (during operation) of concentrations of radionuclides in the environment. (j) The practical implementation of these recommendations will be kept under review by the Commission, and any future revisions will be made in light of this experience.

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GLOSSARY Benthic Pertaining to the fauna and flora at the bottom of the sea or a lake.

Concentration ratio Activity concentration within an organism relative to that in its surrounding habitat (as represented by a particular media such as air, sediment, soil, or water).

Derived Consideration Reference Level A band of dose rate within which there is likely to be some chance of deleterious effects of ionising radiation occurring to individuals of that type of reference animal or plant (derived from a knowledge of defined expected biological effects for that type of organism) that, when considered together with other relevant information, can be used as a point of reference to optimise the level of effort expended on environmental protection, dependent upon the overall management objectives and the relevant exposure situation.

Dose conversion factor A value that enables the dose to an organism to be calculated on the assumption of a uniform distribution of a radionuclide within or external to an organism, assuming simplified dosimetry, in terms of (mGy day-1)/(Bq kg-1).

Emergency exposure situation Emergency exposure situations are exposure situations resulting from a loss of control of a planned source, or from any unexpected situation (e.g. a malevolent act) that requires urgent action to avoid or reduce undesirable consequences.

Environmental exposures All radiation exposures of biota in the natural environment, in addition to natural background exposures that result from human activities. (This term has also been used in previous ICRP documents to refer to human exposures via environmental pathways.)

Environmental radiation protection Measures taken to prevent or reduce the frequency of deleterious radiation effects in animals and plants (biota) in their natural environmental setting to a level where they would have a negligible impact on the maintenance of biological diversity; the conservation of species; or the health and status of natural habitats, communities, and ecosystems.

Existing exposure situation Existing exposure situations are exposure situations resulting from sources that already exist when a decision to control them is taken (including natural radiation, past activities, or following emergencies).

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Exposure situation An exposure situation is the process that includes a natural or man-made radiation source, the transfer of radiation through various pathways, and the exposure of individuals.

Gray (Gy) The special name for the SI unit of absorbed dose: 1 Gy ¼ 1 J kg1.

Iteroparous Reproducing more than once in a lifetime.

Justification The process of determining whether either (1) a planned activity involving radiation is, overall, beneficial [i.e. whether the benefits to individuals and to society from introducing or continuing the activity outweigh the harm (including radiation detriment) resulting from the activity]; or (2) a proposed remedial strategy in an emergency or existing exposure situation is likely, overall, to be beneficial [i.e. whether the benefits to individuals and society (including the reduction in radiation detriment) from introducing or continuing the remedial strategy outweigh the cost and any harm or damage it causes].

Natural environment A collective term for all of the physical, chemical, and biological conditions within which wild animals and plants normally live.

Optimisation of protection (and safety) The process of determining what level of protection and safety makes exposures, and the probability and magnitude of potential exposures, as low as reasonably achievable, economic and societal factors being taken into account.

Pelagic Pertaining to fauna and flora that live near the surface of the sea or a lake.

Planned exposure situations Planned exposure situations are exposure situations resulting from the operation of deliberately introduced sources. Planned exposure situations may give rise both to exposures that are anticipated to occur (normal exposures) and to exposures that are not anticipated to occur.

Radioactive material Material designated in national law or by a regulatory body as being subject to regulatory control because of its radioactivity, often taking account of both activity and activity concentration.

20



Reference Animal or Plant A hypothetical entity, with the assumed basic biological characteristics of a particular type of animal or plant, as described to the generality of the taxonomic level of Family, with defined anatomical, physiological, and life-history properties, that can be used for the purposes of relating exposure to dose, and dose to effects, for that type of living organism.

Representative organism A particular species or group of organisms selected during a site-specific assessment, taking account of their assumed location with respect to the source. In many cases, the actual representative organisms chosen for this purpose may be the same as, or very similar to, the Reference Animals and Plants; however, in some cases, they may be very different.

Semelparous Reproducing only once during a lifetime.

Source Any physical entity or procedure that results in a potentially quantifiable radiation dose (usually in relation to a person or group of persons).

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1. INTRODUCTION 1.1. Background (1) All of the Commission’s recommendations for protection against ionising radiation are based on a framework of aims, fundamental principles, and scope. In its latest revision of its general recommendations (ICRP, 2007), the Commission broadened its scope by introducing a new requirement – that of protecting the environment. This decision followed on logically from a previous ICRP document that had discussed the basis for assessing the impact of ionising radiation on non-human species, the basic principles and approaches to environmental protection generally, and how such information could be applied specifically to environmental radiation protection (ICRP, 2003). (2) The Commission therefore set its aims for the protection of animals and plants, in their natural environmental setting, as being those of. . .. ‘preventing or reducing the frequency of deleterious radiation effects to a level where they would have a negligible impact on the maintenance of biological diversity, the conservation of species, or the health and status of natural habitats, communities and ecosystems’ (ICRP, 2007). In order to achieve this aim, the Commission recognised that exposure to radiation is but one factor to consider, and is often likely to be a minor factor. This also raised the question of how protection of the environment fitted within the Commission’s overall, well-established radiation protection framework for human protection. (3) The Commission stated in Publication 103 (ICRP, 2007), based on the advice given in Publication 91 (ICRP, 2003), that it intended to base the concept of protection of the environment within a scientific and conceptual framework, similar to that which had been developed for the protection of humans, by employing a set of reference models and databases. This proposed framework was further developed in Publication 108 (ICRP, 2008) by explaining the concept and use of a small set of Reference Animals and Plants (RAPs) to explore the issues of relating exposure to dose, and dose to effects, for different types of animals and plants. Publication 108 (ICRP, 2008) included biological descriptions of the RAPs, relevant radiation effects data, and a number of new terms and numerical values, such as RAP-specific dose conversion factors for a variety of radionuclides, and Derived Consideration Reference Levels (DCRLs) as starting points for optimising the level of protection. The overall dataset for these RAPs has been extended recently by the compilation of relevant transfer factors (concentration ratios), describing the relationship between environmental concentrations of a number of radionuclides and the corresponding concentrations in such animals and plants (ICRP, 2009). 1.2. Objectives and scope (4) The present report describes the Commission’s framework for protection of the environment, and how it should be applied within the Commission’s system of protection. This is to ensure that comprehensive and coherent decisions are made in relation to providing protection from any source of exposure, in any specified exposure situation, including non-human species – referred to in this report simply as ‘biota’. 23



(5) The term ‘environmental protection’ is sometimes taken to include the prevention of the contamination of environmental media that are considered to constitute environmental resources (such as soil, water, sediment, and air) of human value with the objective of protecting such natural resources for the future. A typical example is that of guarding against the risk of contaminating groundwater that could be of use to humans with radionuclides from waste disposal. In such cases, the object of protection (e.g. groundwater) is not itself harmed by exposure to ionising radiation, and the concern is essentially regarding the future use of the resource by humans. It thus forms part of the framework of human protection. In the same manner, however, these resources also form part of the network of exposure media for non-human biota. As such, protection of such resources is a mechanism for limiting exposures for both humans and biota. Environmental media are therefore considered by the Commission as ‘pathways’ of exposure, whereas the recommendations relating to protection of biota are derived from an understanding of effects in, and the sensitivity of, the organisms living in a particular environment. Thus, although the protection of resources is an aspect of environmental protection (and often a legal requirement with regard to the principles of sustainable development) that should not be overlooked, it is not the object of this report. (6) The structure of this report is therefore as follows. Following a description of the endpoints of relevance to environmental protection, the development of the Commission’s set of RAPs is reviewed, and the purpose of DCRLs is explained. Consideration is given to how the RAPs may be exposed to radiation, over and above their local levels of natural background radiation. The report describes how the Commission’s framework for protection may be applied to different types of exposure situations, how its application relates to the basic principles of protection, and how reference values based on the DCRLs can be used to inform on the appropriate level of effort relevant to different exposure situations. Further recommendations are made with regard to how the Commission’s advice can be implemented to satisfy different forms of environmental protection objectives, which may require the use of representative organisms specific to a site, and how these may be compared with the reference values. Additional information is given with regard to communication with other interested parties and stakeholders. Issues that may arise in relation to compliance are also discussed, and the final chapter discusses the overall implications of the Commission’s work in this area to date. Annexes A and B provide some numerical information relating to the RAPs, and Annex C considers some existing types of environmental protection legislation currently in place in relation to large industrial sites and practices, and the various ways in which wildlife are protected from various threats arising from such sites.

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2. THE COMMISSION’S FRAMEWORK FOR PROTECTION OF THE ENVIRONMENT 2.1. Objectives of protection (7) The Commission’s aims in terms of environmental protection are to prevent or reduce the frequency of deleterious radiation effects on biota to a level where they would have a negligible impact on the maintenance of biological diversity; the conservation of species; or the health and status of natural habitats, communities, and ecosystems. The biological endpoints of most relevance are therefore those that could lead to changes in population size or structure. Nevertheless, radiation affects individuals, and most available data on the effects of radiation relate to individuals rather than populations. (8) The biological endpoints of interest to individuals that could have a consequence at a population level are those of: . early mortality (leading to changes in age distribution, death rate, and population density); . some forms of morbidity (that could reduce ‘fitness’ of the individuals, making it more difficult for them to survive in a natural environment); . impairment of reproductive capacity by either reduced fertility or fecundity (affecting birth rate, age distribution, number, and density); and . induction of chromosomal damage. (9) Although some of these endpoints, such as mortality or reduced reproductive capacity, could have a direct effect on the population growth rate or structure, the consequences of other endpoints at the population level, such as morbidity and some forms of chromosomal damage, are either not fully understood or are simply unknown. The grouping of effects into those that are known to be stochastic and those that are known to be non-stochastic (as in the case of human radiation protection) is therefore of little value in characterising these endpoints; it is the broader biological consequence that is of interest, particularly at the population level. There cannot be any effect at the population level if no effects occur in any of the individuals of that population, although the inverse is not always the case, because detectable effects in some members of a population would not necessarily have a consequence for the population as a whole. (10) In order to apply the Commission’s recommendations in practice, and to meet its overall objective, a framework would ideally include all of the following elements: . clearly stated local environmental protection objectives that relate to a specific environmental exposure situation; . knowledge of the effects of radiation, at different dose rates, to different tissues, organs, and life stages of the relevant biota relating to such objectives; . estimates of the dose likely to be received by the relevant biota, under those environmental exposure situations, in terms of the tissues, organs, and life stages most likely to be at risk with regard to the relevant biological endpoints; . the number of individuals, or fraction of the relevant population, that would be likely to receive such dose rates, and when; and 25



. the actions, or choice of actions, that could be taken to optimise the level of protection of the relevant biota relating to radiation exposure, bearing in mind other possible threats to the same population. (11) Quite clearly, apart from the first point, this is collectively a daunting and virtually impossible task. The range of biota is immense, and the effects of radiation on them, at different stages in their life cycles, are not only unknown but unknowable. Nevertheless, the Commission believes that there is sufficient information to provide basic guidance and advice on this issue, providing that it is well structured, and logically and scientifically linked to the framework, and system, that has been developed for the protection of human beings. (12) Due to the immense variety of biota, and their presumed response to radiation, any credible system needs to have some key points of reference which provide some form of auditable trail that links the basic elements of the framework together, or at least could do so if further data were forthcoming and it is feasible to obtain such data. The advantage of such a systematic approach is that, as the need for change to any component of the system arises (as in the acquisition of new scientific data, changes in societal attitudes, or simply from experience gained in its practical application), it is possible to consider the consequences of such a change elsewhere within the system, and upon the system as a whole. 2.2. Reference Animals and Plants (13) The Commission developed a small set of RAPs, plus their relevant databases, for a few types of organisms that are typical of the major environments. The RAPs were described to the generality of the taxonomic level of Family, because this is the highest taxonomic level at which the biological features of an animal or plant of relevance to the effects of radiation can be assumed to be relatively constant. They are essentially reference models and not, therefore, necessarily the direct objects of protection themselves (although they could be directly related to them). However, by serving as points of reference, they provide a basis upon which some management decisions can be made. (14) A RAP was therefore defined as. . . ‘a hypothetical entity, with the assumed basic characteristics of a specific type of animal or plant, as described to the generality of the taxonomic level of Family, with defined anatomical, physiological, and lifehistory properties, that can be used for the purposes of relating exposure to dose, and dose to effects, for that type of living organism’. (15) The set of RAPs and the criteria for their selection were set out in Publication 108 (ICRP, 2008). Essentially, the following points were considered, including the fact that a reasonable amount of radiobiological information was already available on these organisms, and they were amenable to future research in order to obtain the necessary missing or imprecise data. It was also considered that they were likely to be

26



exposed to radiation from a range of radionuclides in a given situation, both as a result of bio-accumulation and the nature of their surroundings, and because of their overall life span, life cycle, and general biology. A further consideration was that their life cycles were likely to be of some relevance for evaluating total dose or dose rate, and producing different types of dose–effect responses, and there was a reasonable chance of being able to identify any effects at the level of the individual organism that could be related to radiation exposure. Bacteria and unicellular organisms were excluded because of their high resistance to radiation. It was also considered that their taxonomic Family names should have some form of public or political resonance, so that both decision makers and the general public at large were likely to know what these organisms actually are, in common language. (16) A set of 12 RAPs was therefore identified, but there is nothing sacrosanct about the set. They are all considered to be organisms with a wide geographic distribution and are typical of different environments, in the sense that one might expect to find them there: earthworms in soil; ducks in estuaries; flatfish, crabs, and brown seaweed in coastal waters; trout in rivers and lakes; frogs in marshland; deer, pine trees, wild grass, and bees across much of the temperate part of the globe; and small mammals such as the rat being virtually ubiquitous. The set is also essentially one of wild, rather than domesticated, animals and plants, although many of them are farmed in some countries in one way or another. With regard to the need for reference models to represent typical farm animals – primarily large mammals that live essentially in a human environment – it was considered that the use of the human animal itself was probably sufficient for such managed environmental or ecological situations. (17) Publication 108 (ICRP, 2008) also included reference data sets (dose conversion factors) by which concentrations of radionuclides inside or outside the RAPs could be converted into dose rates at an approximate whole-body level, and Publication 114 (ICRP, 2009) provided reference data sets (concentration ratios) by which concentrations in the ambient media, under equilibrium conditions, could be related to whole-body concentrations for the relevant RAPs. 2.3. Derived Consideration Reference Levels (18) A review of all of the known data on the effects of radiation relevant to the RAPs was also made, and the information is summarised (Annex A) in terms of increasing orders of magnitude of dose (ICRP, 2008). From these compilations, a band of dose rate for each RAP, spanning one order of magnitude, was selected for the purpose of providing a starting point for considering what action, if any, should be undertaken in relation to protection of the RAPs under different exposure situations. The term used for these bands is ‘DCRLs’. A DCRL is. . .. . . ‘a band of dose rate within which there is some chance of deleterious effect from ionising radiation occurring to individuals of that type of RAP (derived from a knowledge of defined expected biological effects for that type of organism) that, when considered together with other relevant information, can be used as a point of reference to optimise the level of effort expended on environmental protection, dependent upon the overall

27



management objectives and the relevant exposure situation’ (ICRP, 2008). The values themselves are very similar to those that have been derived by other reviews and analyses of radiation effects data from a wider range of biota, and grouped in various ways (Larsson, 2012). 2.4. Exposure pathways (19) In assessing doses and effects to representative organisms, all relevant exposure pathways need to be considered. . Inhalation of (re)suspended contaminated particles or gaseous radionuclides. This pathway is relevant for terrestrial animals and aquatic birds, mammals, and herptofauna. Respired or otherwise volatile forms of radionuclides may also contribute to the exposure of plants via gaseous exchange. . Contamination of fur, feathers, skin, and vegetation surfaces. This has both an external exposure component (radionuclides on or near the epidermis cause irradiation of living cells beneath), plus an internal exposure component, as contaminants are ingested and incorporated into the body of an animal. This pathway is clearly of considerable relevance to terrestrial fauna in accident situations. . Ingestion of lower-trophic-level plants and animals. This leads to direct irradiation of the digestive tract, and internal exposure if the radionuclide becomes assimilated and distributed within the animal’s body. . Direct uptake from the water column. This pathway is relevant to truly aquatic organisms (e.g. fish, molluscs, crustaceans, macro-algae, and aquatic macrophytes), leading to both direct irradiation of, for example, the gills or respiratory system, and internal exposure if the radionuclide becomes assimilated and distributed within the animal’s body. . Ingestion of contaminated water. In addition to imbibition (drinking) by animals, the corresponding pathway for plants relates to root uptake of water. . External exposure.This essentially occurs from exposure to g irradiation and, to a lesser extent, b irradiation originating from radionuclides present in the organism’s surroundings. For small organisms, irradiation from a particles is also relevant. The configuration of the source relative to the target clearly depends on the organism’s ecological characteristics and habitat. A benthicdwelling adult fish will, for example, be exposed to radiation from radionuclides present in the water column and deposited in sediment, but a pelagic fish may only be exposed to the former. The eggs of the fish, however, may be laid on the sediment or may float near the surface. (20) The predominance of any particular exposure pathway, for any particular type of animal or plant, will not only be determined by the biology of the animal and its relevant stage in the life cycle, but also by the type of exposure situation; these are discussed in Chapter 3.

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3. APPLICATION 3.1. Types of exposure situations (21) All biota are exposed to ionising radiation from natural sources, and many are, or may be, exposed to man-made sources. The processes causing these exposures can be considered as a network of events and situations. Each part of the network starts from a source. Radiation or radioactive material passes through environmental or other pathways, leading to the exposure of biota that can be expressed in terms of dose. Protection of the relevant biota can be achieved by taking action at the source, or at points in the exposure pathways, and occasionally by modifying the location or characteristics of the exposed biota. The available points of action therefore have a substantial effect on the system of protection. (22) As stated in Publication 103 (ICRP, 2007), the Commission intends that its recommendations should be applied to all sources of radiation in the following three types of exposure situations. . Planned exposure situations are exposure situations resulting from the operation of deliberately introduced sources. Planned exposure situations may give rise to exposures that are anticipated to occur (normal exposures) and to exposures that are not anticipated to occur. . Emergency exposure situations are exposure situations resulting from a loss of control of a planned source, or from any unexpected situation (such as a malevolent event), that requires urgent action in order to avoid or reduce undesirable exposures. . Existing exposure situations are exposure situations resulting from sources that already exist when a decision to control them is taken. (23) In the context of this report, planned exposure situations are situations involving the discharge and disposal of radioactive waste, decommissioning of installations, and the activities related to eventual remediation and decontamination work of resulting contaminated sites. Emergency exposure situations are situations that may occur as a result of an accident, a malicious act, or any other unexpected situation in which control of the source has been lost and urgent actions are required in order to avoid or reduce undesirable consequences. Existing exposure situations are situations where the source already exists and a decision on control has to be taken. They include prolonged exposure situations after emergencies. 3.2. Principles of protection (24) The Commission has three fundamental principles that underlie its system of radiological protection: justification, optimisation of protection, and application of dose limits. (25) Of these, the principle of the application of dose limits for protection of people applies in relation to occupational and public exposures in planned exposure situations, other than medical exposure of patients. The use of dose limits is not 29



recommended for protection against occupational and public exposures in emergency or existing exposure situations. The Commission does not, however, recommend any general form of dose limitation for biota. This is because the need for dose limits to ensure equity for human exposures does not clearly exist in protection of the environment. In addition, the objectives of such protection, and the highly variable nature of the exposure situations, make it difficult to establish limits that would be scientifically defensible. (26) With regard to the principle of justification, this is the process of determining whether: (1) a planned activity involving radiation is, overall, beneficial (i.e. whether the benefits to individuals and to society from introducing or continuing the activity outweigh the harm, including radiation detriment, resulting from the activity); or whether (2) a proposed protection strategy in an emergency or existing exposure situation is likely, overall, to be beneficial (i.e. whether the benefits to individuals and to society, including the reduction in radiation detriment, from introducing or continuing the strategy, outweigh its cost and any harm or damage it causes).There are two different approaches to applying the principle of justification that depend upon whether or not the source can be controlled directly. The first is used in the introduction of new activities, where radiological protection is planned in advance and the necessary protective actions on the source can be taken. The second approach is used where exposures can be controlled mainly by action to modify the pathways of exposure, and not by acting directly on the source, such as existing exposure situations and emergency exposure situations. The benefits are deemed to apply to humans and society as a whole, and thus also to biota; the term ‘harm’ encompasses any increased risk from radiation exposure, and this will also apply to humans and biota. (27) As the principle of justification also includes the need to take account of future harm and benefits, the Commission considers that the potential risk of radiation harm to the environment should also be considered within the overall evaluation of whether or not an activity or action does more harm than good. Such evaluations – that will ultimately be made by governments or regulatory bodies – are likely to be part of more inclusive and holistic assessments relating to all of the impacts of introducing activities where control is exercised over the source. (28) With regard to remedial strategies, in the context of emergency and existing exposure situations, consideration should also be given to the likely consequences for radiation exposure of biota (as, for example, by way of relocating contaminated material), so that the overall outcome does more good than harm. These decisions must be made in the more inclusive and holistic context of benefits and impacts, and again the Commission notes that radiation exposure is often not the dominant impact to biota from proposed actions. (29) The principle of optimisation of protection is intended for application to those situations that have been deemed to be justified in the first place. The principle is central to the system of protection and applies to all exposure situations; it considers all exposures, and thus includes environmental exposures. It is a source-related process, aimed at achieving the best level of protection under the prevailing 30



circumstances through an ongoing, iterative process. The Commission has drawn attention to the fact that it is always necessary to consider the relationships between the different categories of exposure (ICRP, 2006). Thus, for example, in optimising the level of protection in the case of occupational exposure, it is also necessary to consider the potential effect on public exposure (e.g. as a result of releasing more radioactive material into the environment in order to reduce occupational exposures). If the scale of release is significant, it is also necessary to consider any impact on biota. (30) To assist in the optimisation process for human exposures, the Commission has defined dose constraints for restricting, during the planning process, the range of acceptable outcomes for occupational and public individual exposures in planned exposure situations in relation to a source. In emergency and existing exposure situations, the Commission has also recommended that reference levels should be used in conjunction with the optimisation of protection to restrict occupational and public exposures. The Commission believes that steps taken to protect the environment should fall within the concept of optimisation. 3.3. Reference values for environmental protection based on Derived Consideration Reference Levels (31) The Commission recommends that reference values should also be used for protection of the environment, using the DCRLs relevant to the different RAPs as points of reference to inform on the appropriate level of effort that should be expended on environmental protection, dependent on the overall management objectives, the exposure situation, the actual fauna and flora present, and the numbers of individuals thus exposed. The DCRLs have been defined in terms of bands of dose rates spanning one order of magnitude relevant to each RAP (Fig. 3.1). (32) The Commission recommends that DCRLs should be used under all circumstances where there is, or may be, an environmental exposure of significance above the natural background locally experienced by the relevant biota. The use of the DCRLs in each exposure situation is elaborated as follows. (33) In planned exposure situations, the lower boundary of the relevant DCRL band should be used as the appropriate reference point for protection of different types of biota (Fig. 3.2) within a given area during the planning of controls to be applied to a source. As the DCRL bands apply to animals and plants within a given location, the extent of such an area needs to be determined in advance relative to the overall conservation objectives. In the case of multiple sources of exposure (e.g. from historical discharges or multiple sites), these other sources should be taken into account in comparison with the DCRLs when assessing protection options. If the assessed dose rates are below the appropriate reference point, the level of control is determined by selection of the most reasonable protective action. (34) Consideration should always be given as to whether all reasonable actions have been taken under the prevailing circumstances, following the general guidance given in Publication 101 related to the principle of optimisation (ICRP, 2006). If the 31



1000

100

mGy/d

10

Bee Worm

1

0.1

Grass

Deer Rat Pine tree

Crab

Trout Frog Flatfish Seaweed

Duck

0.01

0.001

Increasing dose rate

Fig. 3.1. Derived Consideration Reference Levels (DCRLs) for environmental protection for each Reference Animal or Plant (RAP), the RAPs being grouped according to their terrestrial, freshwater, or marine habitat.

D C R L

DCRL for relevant RAP Reference point for the sum of all sources

Fig. 3.2. Relationship between Derived Consideration Reference Levels (DCRLs) and sources under planned exposure situations. RAPs, Reference Animals and Plants.

assessed value is greater than the reference point, further actions should be considered. Protective actions resulting in doses above the upper boundary of the relevant DCRL band imply a stronger need to consider further protection efforts. (35) Planned exposure situations relating to the management of long-lived wastes are especially difficult with regard to protection of the environment because the biosphere is likely to change, and may even change substantially, over the long time frames that are considered in such waste disposal. Such changes may entail alterations that are natural, or are enhanced or perturbed through human action. The default case for protection, and protective actions, should therefore be the set of 32


Increasing dose rate


Potential for dose rate reduction

Minimum level of ambition

D C R L

DCRL for relevant RAP

Fig. 3.3. Relationship between Derived Consideration Reference Levels (DCRLs) and ambition to reduce exposures in existing exposure situations. RAPs, Reference Animals and Plants.

RAPs, bearing in mind that this set was chosen deliberately because its components are considered to be typical biotic types of the major environmental domains of land, sea, and fresh water. (36) Although their use offers a challenge for waste management which is similar to that of demonstrating compliance with dose/risk standards for humans, it also offers an additional line of argument and reasoning in building a safety case, using endpoints that are different from, but complementary to, the protection of human health. Consideration of environmental protection, where appropriate, will thus broaden the basis for risk-informed decision making, and address issues that may have differing levels of importance for different stakeholders. It should, however, be noted that the DCRLs are not intended to apply within the waste facility itself. (37) Planned exposure situations may also involve consideration of the possibilities and magnitude of the consequences of potential events or accidents (potential exposures). Thus, during planning phases, there may be a need to consider different siting options for a specific source (such as placing an outlet into a river, an estuary, or the sea) with regard to the potential environmental impact of accidental releases of radionuclides into these different media. It may also include a need to consider the potential impact of accidental releases (such as an accidental release into the aquatic medium or the atmosphere) from a defined source on the different surrounding media (terrestrial, freshwater, or marine environments) and the mitigating measures that may be available. The DCRL bands may serve as a point of reference in such assessments, and be used as a mechanism to compare impacts in the overall siting and emergency planning activities. (38) For existing exposure situations, and emergency exposure situations where control of the source has still not been obtained, if the dose rates are above the relevant DCRL band, the Commission recommends that the aim should be to reduce exposures to levels that are within the DCRL bands for the relevant populations, with 33



full consideration of the associated radiological and non-radiological consequences (Fig. 3.3). (39) However, the Commission recognises that it may be difficult, or impractical, to significantly reduce the concentrations or quantities of radioactive material that exist in the affected environment. If dose rates are within the band, the Commission believes that consideration should be given to reduce exposures, assuming that the costs and benefits are such that further efforts are warranted. Thus, in the case of existing exposure situations, the DCRLs are to be used as the criteria for mitigating environmental exposures, just as reference levels are used for mitigating individual exposures for human protection in such situations. In emergency exposure situations, the levels of exposure may be orders of magnitude greater than the DCRLs. The practical implications of this situation are discussed in Chapter 4.

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4. IMPLEMENTATION 4.1. Introduction (40) The objectives for evaluation of the impact of enhanced radiation in the environment with regard to human exposures under different exposure situations are well established. With regard to exposures to biota, however, the needs may arise for reasons that stem from a wide range of environmental management requirements. These may be of a very general nature, or specifically defined in order to meet national or international legal requirements including, in some cases, a specific need in relation to specific types of habitat or to specific types of fauna or flora. The practical consequence, however, is that this need may include any of the following objectives: . compliance with the spirit or the letter of transnational general pollution or wildlife-protection obligations; . compliance with national pollution control licensing requirements relating to particular industrial practices or to specific sites or areas; . compliance with the requirements of specific national wildlife and habitat protection legislation; . compliance with specific environment-based industry needs, such as those relating to fisheries, forestry, farming, etc.; or . general assurance of the public or their representatives, at national or international level, of the likely environmental impact of any actual or proposed specific practices, and demonstration of the ability to deal with any consequences should accidents occur. (41) In application of the principle of optimisation of protection of the natural environment, an integrated approach is important. Optimisation is always implemented through a procedure aimed at achieving the best level of protection under the prevailing circumstances through an ongoing, iterative process that involves: characterisation of the exposure situation; selection of the representative organisms; identification of the possible protection options; selection of the best protection option under the prevailing circumstances guided by the DCRLs as a point of reference; and . implementation of the selected protection option. . . . .

4.2. Selecting representative organisms and their relationships to Reference Animals and Plants 4.2.1. Basic assumptions (42) When a specific situation has been identified, it is necessary to identify the representative organisms. These may be among the RAPs, and data on DCRLs can be used without further consideration. In other circumstances, the representative 35



Protection desired at community or ecosystem level

Population status of species typical of the ecosystem

Key biological parameters affecting population status of typical species (Mortality, morbidity, reduced reproductive success, chromosomal damage)

Factors affecting the key biological parameters that are amenable to control

Fig. 4.1. Relationships between the aims of protecting a community or ecosystem by way of focusing on the key species and the factors affecting their key biological parameters.

organisms may not be well represented by any of the RAPs, and the differences will need to be assessed. (43) One area in which selection might be more difficult is that involving the need to meet environmental protection criteria that relate to protecting the entire habitat, or ecosystem as a whole, as is often the case with regard to nature conservation. The same difficulties apply to all aspects of managing such habitats, and it is customary to break down the problem as illustrated in Fig. 4.1. (44) In order to assess the level of radiological impact for comparison with the reference criteria, the location of the representative organism(s) needs to be considered and defined carefully. Due to the characteristics of the distribution of radionuclides in the environment, the levels of exposure of individuals, and groups of individuals of the same species, may change drastically depending on their location. The concept of a group of individuals that is representative of those more highly exposed should be borne in mind when making such assessments. (45) In practice, because of the impossibility of being able to understand all of the numerical components of an ecosystem, subsets of typical organisms are used as indicators of the whole. The use of representative organisms and their links to the set of RAPs in such situations is shown in Fig. 4.2. In fact, many potential representative organisms have been identified in relation to satisfying the requirements of nature conservation (Larsson, 2004, 2008), and applied in relation to different ecological sites (EA, 2009). (46) Nevertheless, because of the vast variety of potential representative organisms, there may be considerable differences between the chosen or necessary representative organisms and the set of 12 RAPs. Such differences will fall into one of four areas. If the set of RAPs does not include all or any of the animal or plant types requiring 36



Protection at community or ecosystem level

Population status of species typical of the ecosystem Representative organisms

Key biological parameters affecting population status of typical species (Mortality, morbidity, reduced reproductive success, chromosomal damage)

Derived Consideration (Reference) Levels (based on dose rates likely to affect such biological parameters in such types)

Reference Animals and Plants (Typical biotic types of major ecosystem)

Fig. 4.2. Relationships between the aims of protecting a community or ecosystem and the use of representative organisms and Reference Animals and Plants.

protection, then, compared with the RAPs, that are, by definition, a reference set, there will be differences from the reference set in terms of: . their biology, such as life span or life cycle; . their dosimetry, because of size, shape, or location; and . their response to radiation at similar rates of (or total) dose. Such differences were considered in the original RAP document (ICRP, 2008) and are discussed briefly below. 4.2.2. Differences in biology (47) The RAPs have to be considered merely as points of reference. It is simply not possible to cater for all of the biotic types in which environmental protection interests may be expressed, and there will clearly be situations in which the biotic objects of interest will be different from those of the RAPs. Such differences could be relatively small, such as differences in the time span of a particular stage in the life cycle, or in overall life span. In other cases, differences in biology could make large differences to estimates of exposure to certain radionuclides via different pathways. Reference to their natural background dose rates in that area, if known, may therefore be of some value in considering the extent to which the application of this approach to other types of animals and plants would make a significant difference, 37



simply on the basis of differences in their basic biology. One way in which differences from the set of 12 RAPs would obviously make a difference, however, is that of shape and size, and thus with regard to estimates of dose received. 4.2.3. Differences in radiation dosimetry (48) Issues relating to differences in dosimetry are more easily addressed. There are several aspects of the extrapolation and interpolation of the basic dosimetry models used for the RAPs to other biota, including shape, size, and location. With regard to shape, matters have been simplified considerably by the use of solid spheres and ellipsoids, although it is recognised that such shapes may not readily extrapolate to some forms of organism. Nevertheless, some flexibility is possible. (49) The RAPs represent a wide range of ecosystems, habitats, masses, and shapes, and allow estimation of a wide range of dose rates to biota caused by radionuclides in the environment. However, the variety of the flora and fauna in the natural world is enormous. (50) For external exposure, dose conversion factors decrease with the size of the animal due to the increasing self-shielding effect. The differences in dose conversion factors for external exposure are more pronounced for low-energy emitters because of the effect of self-shielding. (51) For internal exposure to g emitters, dose conversion factors increase in proportion to the mass of the organism due to the higher absorbed fractions, the dependence being more pronounced for high-energy photon emitters (e.g. 137Cs/137mBa). For a and b emitters, dose conversion factors for internal exposure are, to some extent, size-independent if it is assumed that they are evenly distributed within an organism, which is unlikely to be the case. The influence of the shape of the RAPs on both external and internal exposure is relatively small. 4.2.4. Differences in radiation effects (52) In contrast to dosimetry, it is not yet possible to provide recommendations regarding how to perform extrapolations that have general applicability in relation to radiation effects, and thus each case has to be considered carefully on its own merits. Due to the relative paucity of information, the main cases for extrapolations, and challenges for methodological development, include the following. There are clearly issues with regard to extrapolating from high acute doses and dose rates of low-linear energy transfer g and x rays to lower doses accumulated at lower dose rates. In the radiobiological and radio-ecological literature, the qualifiers ‘low level’, ‘chronic’, ‘higher’, ‘acute’, etc. are often used without any definition. However, a radiation exposure lasting for several days may be effectively ‘chronic’ for a shortlived organism, and yet effectively ‘acute’ for a long-lived organism. Unfortunately, there are very few data that relate directly to the chronic, low-level irradiation conditions of relevance for animals and plants in the wild (i.e. exposures at dose rates of 0.1–1 mGy day1 over the life span of the organisms), and the response endpoints most commonly assessed after acute, high-dose irradiation are not those that are relevant in such situations. 38



(53) Although the information does not cover all taxa to the same depth, there is nevertheless clear evidence that there are substantial variations in the radiosensitivity of organisms both within, and between, taxonomic groups; this difference in sensitivity also extends to different stages of the life cycle for any given organism. Extrapolation may be easier when organisms are more closely related, and the effects endpoints considered for the relevant stage in the life cycle are more similar. Interactions at community and ecosystem level, however, can be particularly complex, as discussed in a recent publication by the International Union of Radioecology (IUR, 2012). Data sets have been developed for a large range of animals and plants (other than those relating to the RAPs), and these were summarised in the final report on the European Council’s fifth framework programme (Larsson, 2004). 4.3. Additional considerations (54) One issue that is likely to arise more than any other is the extent to which one should be precautionary, for one reason or another. The reasons could be due to the current lack of data at lower dose rates for many types of RAPs, or because of other uncertainties in the data or their derivation. At present, the DCRLs make no allowance for relative biological effectiveness, a subject still under consideration by the Commission (Higley et al., 2012). Equally, a degree of precaution may be considered necessary because of the importance of the site or habitat, or the importance of the actual species present or likely to be present. When this is the case, such additional precautionary measures should be identified separately for transparency in the assessment. (55) Care should also be taken in making decisions with regard to populations of animals or plants, as opposed to small groups of individuals. Population modelling approaches demonstrate that the linkage between radiation effects in the individuals and in the population is very complex, and may be dependent on factors other than radiation doses and dose–response relationships. Publication 108 (ICRP, 2008) discusses this issue, and Appendix B gives reference population size characteristics. (56) With regard to responding to an actual emergency event, or accidental release of radionuclides into the environment, consideration of environmental protection may not be an immediate priority depending on the extent to which human exposures, or human food chains, are likely to be affected. However, even where human exposure concerns predominate, consideration should nevertheless be given to the environmental consequences of the possible options available to achieve the adequate level of human protection. (57) Human exposures may be minimal or readily controlled. Although the options available for mitigation are usually very limited with respect to the protection of biota, consideration should be given to the different environmental radiological consequences of either dispersing the contaminated medium further by physical means, or restricting its dispersion (such as by using chemicals to precipitate radionuclides from a water column, or using simple physical barriers). (58) After the occurrence of an accident, the framework of the DCRLs, and the set of indicative population impacts relative to the doses they receive, may be useful in 39



Dose rate to relevant biota DCRL

Order of magnitude bands of dose rate

Severe Effects Level

Time after event

Fig. 4.3. Potential use of severe-effects bands, relative to Derived Consideration Reference Levels, to relate exposure of relevant biota following an accidental or emergency release of radionuclides into the environment.

communicating the implications of the situation to stakeholders, particularly in relation to environmental conditions where humans have been removed from the area, and food chains leading to human exposure have been severed. Within the chemical industry, the concept of such severe-effect reference levels is often used. The Commission notes that this type of level could be considered approximately equivalent to a band of doses two orders of magnitude above the DCRL band, in view of the type of effects that these levels represent. Fig. 4.3 illustrates the potential use of severe-effects levels. With the passage of time immediately following an accidental release, information to the public can be conveyed in terms of an assessment of the environmental situation relative to a predetermined reference point, and thus the results of mitigation actions – or simply the effect of natural events – can be readily assessed and evaluated. 4.4. Stakeholder involvement (59) The role of stakeholders should always be recognised in the wider decisionmaking process. Indeed, there is a requirement in the Joint Convention on the Safety of Spent Fuel Management and Radioactive Waste Management to consult contracting parties in the vicinity of a facility (in so far as they are likely to be affected by that facility) and provide them, upon their request, with general data relating to the facility to enable them to evaluate its likely safety impacts upon their territory (IAEA, 1997). Stakeholders include individuals and groups who have a personal, financial, legal, or legitimate interest in policy or recommendations that directly affect their well-being or that of their environment. In most cases, the role of stakeholders is to aid and inform the decision-making process, but there may be situations where stakeholders have the authority and responsibility for making or recommending decisions (such as a nationally appointed board or committee). 40



Generally, however, the government agencies or the regulators are the decision makers, and the stakeholders help in the process by providing information and guidance related to decisions being made. (60) Stakeholders can be helpful in determining the reasonableness, sustainability, and consistency of data used in the decision-making process. Collaboration with stakeholders can improve the quality, understanding, and acceptability of the assessment significantly, and also strengthen support for the process and the results. If stakeholder involvement is used as part of the overall decision-making process, however, guidelines should be established at the beginning to ensure that the process is effective and meaningful for all parties. Some of these guidelines include, but are not limited to, the following: . clear definition of the role of stakeholders at the beginning of the process; . agreement on a plan for involvement; . provision of a mechanism for documenting and responding to stakeholder involvement; and . recognition, by operators and regulators, that stakeholder involvement can be complex and can require additional resources to implement. (61) The Commission understands that the concept of stakeholder involvement may vary significantly between countries for cultural, societal, and political reasons. The value and extent of stakeholder involvement should therefore be considered by individual authorities in each country. Nevertheless, the Commission believes that stakeholder involvement can play an important role in the implementation, understanding, and acceptance of ICRP’s system of environmental protection.

41



5. COMPLIANCE (62) With regard to environmental exposures, the Commission would expect that the need for consideration of exposures to biota would apply mainly to significant sources where there may be activities generating waste, discharges with significant concentrations of radionuclides, or when significant inventories of radionuclides are present on a site. The precise details of where a reasonable line should be drawn, however, will vary considerably between countries, particularly in relation to the general environmental legislation applying to the areas into which any radioactive materials may be released, or upon which they may be stored. The Commission therefore recommends that the relevant national authorities should articulate clearly when such considerations must be part of the decision-making process. (63) The Commission believes that if the processes and procedures described in this report are undertaken, then, on the basis of current knowledge, it should be possible to demonstrate compliance with the various forms of legislation relating to protection of the environment with respect to ionising radiation. The results of the decisions described in this report will lead to the specification of conditions on the authorisation of the source. The Commission believes that this could normally be approached by reference to radionuclide concentrations in different environmental media that can be related to estimates of dose rates to the relevant representative organisms over a suitable spatial area. Once these conditions have been established, compliance can be demonstrated on a regular basis, just as it is today for the protection of humans in planned exposure situations. (64) Wherever possible, protection of the environment from a source should complement controls to protect the public and not add unnecessarily to its complexity. The Commission therefore believes that, having essentially clarified the basis upon which decisions relating to protection of the environment can be made – by way of a framework relating exposure to dose, and dose to effect, for different types of organisms (the set of RAPs) – the demonstration of protection of both humans and nonhuman species as a result of normal planned exposure situations could well be integrated in a relatively simple manner. This could be based solely on assessments (at the design stage) and measurements (during operation) of concentrations of radionuclides in the environment, as suggested when the concept of RAPs was first raised and subsequently elaborated (Pentreath, 1999, 2012). In planned exposure situations, environmental impact assessments are required to assess the impacts of routine activities, and are likely to require an evaluation of the likelihood and the possible magnitude of potential consequences of different scales of accidents on the environment. (65) Existing and emergency situations would need to be examined on a case-by-case basis. In both situations, DCRLs can be used as tools to inform decisions with regard to consequence management alternatives. The Commission’s recommendations are intended to function within this existing framework of regulatory controls.

43



6. DISCUSSION AND CONCLUSIONS (66) The Commission has developed a comprehensive and systematic framework for radiological protection, based on the principles of justification, optimisation of protection, and limitation of individual doses. Also included is a set of modelling approaches for relating exposure to radiation and radioactive materials to dose, and hence the risk. The advantage of such a framework approach has been that, as the need for adaptation and evolution of the system has arisen, it has been possible to consider the consequences of such a change elsewhere within the system, and thus upon the system as a whole. The explicit consideration of the actual or potential consequences of radiation effects upon the natural environment is just such an evolution. The Commission has therefore proceeded in a manner similar to that developed for human radiological protection, in that it has examined the broader sociological context in Publication 91 (ICRP, 2003), the science base in Publications 108 and 114 (ICRP, 2008, 2009), and how it might be applied to different exposure situations (this report). (67) A key step in the development of the scientific framework for human protection was the development of a model then known as ‘Reference Man’, the subsequent development of which has served as a conceptual and analytical tool for many of the Commission’s numeric analyses and resulting conclusions. For humans, a substantial body of epidemiological information exists with regard to exposures and risk that, together with the linear-non-threshold model, plus experimental animal data, allows generally agreed levels of risk to be translated into dose. It is also possible to relate concentrations of radionuclides in the environment into internal and external dose rates using radiation and tissue weighting factors. Hence, for a given set of radionuclides in the environment, regardless of their origin or quantity, one can relate that to dose, and thus to risk, and thus to the basic principles of justification, optimisation, and limitation. (68) For other species, the situation is different. Notwithstanding the fact that it is necessary to directly address the issue of the extent to which the environment itself is protected for the satisfaction of many international and national legislative requirements, one also has to consider the present state of scientific knowledge, and how this can be interpreted and used, in a pragmatic and simple manner, for the purposes of environmental protection. Despite the need for more scientific information, the Commission believes that it has been sensible and timely to draw together, in a consistent manner, existing data for a limited set of different types of organisms (the RAPs) to serve as a basis for an environmental protection framework. With regard to radiation effects for this set, all that can be concluded is that it is possible to discern bands of dose rates within which it is known, or suspected, that there may be adverse effects for individuals of that type of organism. These bands, or DCRLs, have therefore been identified as dose rate bands within which, if experienced or expected, one should stop and consider further what best to do in the context of justification and optimisation decisions. These values are not limits and are not intended to be used in that manner. 45



(69) The Commission therefore believes that, given the present state of knowledge, and of ignorance, it would be prudent to use the DCRLs as indicated in this report for different exposure situations. In doing so, the Commission has thus extended its overall system of radiation protection, but has attempted to do so in a manner that is consistent with, and sits within, the overall framework of protection that has evolved for the protection of humans and which now extends to the natural environment. (70) In situations where there are pathways leading to human exposure, the process of optimisation of protection for the public will itself have a great influence on reducing the actual quantities released in planned exposure situations. This, in turn, will lead to a consequential reduction in the doses received by biota. Where human exposures, or pathways leading to such exposures, are lacking or are of minor concern, the system outlined in this document should serve to demonstrate explicitly that the environment can and will be protected in relation to that specific exposure situation. (71) Implementation of optimisation of protection will always focus on source management in planned exposure situations, and exposure pathway management in emergency and existing exposure situations. The lower end of the DCRL bands can be used as points of reference for decision making in planned exposure situations. Similarly, the DCRL bands themselves can be used as references to inform optimisation decisions in emergency and existing exposure situations. (72) The practical implementation of these recommendations will be kept under review by the Commission, and any future revisions will be made in light of this experience.

46


REFERENCES EA, 2009. Environment Agency, Habitat assessment for radioactive substances. Science Report SC060083/SR1, UK. Higley, K.A., Kocher, D.C., Real, A.G., et al., 2012. Relative biological effectiveness and radiation weighting factors in the context of animals and plants. Proceedings of the First ICRP Symposium on the International System of Radiological Protection. Ann. ICRP 41(3–4). IAEA, 1997. Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. INFCIRC/546, International Atomic Energy Agency, Vienna. ICRP, 2003. A framework for assessing the impact of ionizing radiation on non-human species. ICRP Publication 91. Ann. ICRP 33(3). ICRP, 2006. The optimization of radiological protection: broadening the process. ICRP Publication 101b. Ann. ICRP 36(3). ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37(2–4). ICRP, 2008. Environmental protection: the concept and use of Reference Animals and Plants. ICRP Publication 108. Ann. ICRP 38(4–6). ICRP, 2009. Environmental protection: transfer parameters for Reference Animals and Plants. ICRP Publication 114. Ann. ICRP 39(6). IUR, 2012. Towards an ecosystem approach for protection with emphasis on radiological hazards. IUR Report 7, 2nd Edition. Larsson, C-M., 2004. The FASSET framework for assessment of environmental impact of ionizing radiation in European ecosystems – an overview. J. Radiol. Prot. 24, A1–A12. Larsson, C-M., 2008. An overview of the ERICA integrated approach to the assessment and management of environmental risks from ionizing contaminants. J. Environ. Radioact. 99, 1364–1370. Larsson, C-M., 2012. Biological basis for protection of the environment. Proceedings of the First ICRP Symposium on the International System of Radiological Protection. Ann. ICRP 41(3–4). Pentreath, R.J., 1999. A system for radiological protection of the environment: some initial thoughts and ideas. J. Radiol. Prot. 19, 117–128. Pentreath, R.J., 2012. Clarifying and simplifying the management of environmental exposures under different exposure situations. Proceedings of the First ICRP Symposium on the International System of Radiological Protection. Ann. ICRP 41(3–4).

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APPENDIX A: TABLES OF DOSE RATES AND EFFECTS FOR REFERENCE ANIMALS AND PLANTS Table A.1. Dose rates and effects [Derived Consideration Reference Levels (shaded)] for Reference Deer, Rat, and Duck. Dose rate (mGy day1)

Reference Deer

Reference Rat

Reference Duck

>1000

Mortality from haemopoietic Mortality from haemopoietic Mortality in adults (LD50/30 syndrome (LD50/30 1–8 Gy) syndrome in adults (LD50/30 7–11 Gy) 6–10 Gy)

100–1000

Reduction in life span due to Reduction in life span due to Long-term effects on develvarious causes various causes oping embryos

10–100

Increased morbidity. Possible Increased morbidity. Possible Increased morbidity reduced life span. Reduced reduced life span. Reduced reproductive success reproductive success

1–10

Potential for reduced repro- Potential for reduced repro- Potential for reduced reproductive success due to ductive success due to sterility ductive success due to reduced fertility in males and reduced hatchling viability of adult males females

0.1–1

Very low probability of effects

0.01–0.1

No observed effects

No observed effects

No information

1000

Mortality in adults (LD50/ Mortality in embryos (0.3–19 Gy LD50) depending on embryonic 160 19 Gy); mortality in tadpoles (LD50/30 17 Gy) stage

Mortality in adults (LD50/50 30 Gy); mortality in eggs (LD50 1 Gy)

100–1000

Mortality in eggs (LD50/40 0.6 Gy)

Potential for increased morbidity

Some mortality expected in larvae and hatchlings

10–100

No positive effect information

Some deleterious effects expected on young fish (e.g. reduction in resistance to infections). Reduced reproductive success

Reduced reproductive success

1–10

No positive effect information

Possible reduced reproductive success

Possible reduced reproductive success due to reduced fertility in males

0.1–1

No information

No information

No information

0.01–0.1

No information

No information

No information

1000

Mortality in adults (20– 3000 Gy LD50); larvae (1–2 Gy LD50)

Mortality in adults (420 Gy LD50/40)

Mortality in adults (650 Gy LD50/30)

100–1000

Possible reduced reproductive success due to effects on gonads and pupal mortality

Probable effects on growth rates and reduced reproductive success

Some morbidity and reduced reproductive success

10–100

No information

No information

Effects unlikely

1–10

No information

No information

No information

0.1–1

No information

No information

No information

0.01–0.1

No information

No information

No information

1000

Mortality (5–16 Gy LD50)

Mortality (16–22 Gy LD50)

100–1000

Mortality of some trees after Reduced reproductive prolonged exposure capacity

Effects on growth rate

10–100

Mortality of some trees after Reduced reproductive very long exposure. Growth capacity defects. Reduced reproductive success

Potential effects on growth rate and reproductive success

1–10

No information Morbidity as expressed through anatomical and morphological damage. Prolonged exposure leads to reduced reproductive success

Potential effects on growth rate

Reference Brown Seaweed Deleterious effects expected at very high dose rates. No LD50 data

0.1–1

No information

No information

No information

0.01–0.1

No information

No information

No information

ICRP's approach to protection of the living environment under different exposure situations.

ICRP Publication 126: Radiological Protection against Radon Exposure.

Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129.

Evaluation of effective dose conversion coefficients for Korean adults during medical x-ray examinations up to 150 keV through comparison with ICRP Publication 74 and ICRP Publication 116.

Overview of ICRP Committee 3 'Protection in Medicine'.

Overview of ICRP Committee 2 'Doses from Radiation Exposure'.

Use of the ICRP system for the protection of marine ecosystems.

Radiation protection of the eye lens in medical workers--basis and impact of the ICRP recommendations.

Cancer Risk Assessment in Welder's Under Different Exposure Scenarios.

Radiation exposure to angiographers under different fluoroscopic imaging conditions.

Rat lung response to PM2.5 exposure under different cold stresses.

Spine protection in the austere environment.

Peroxidase(s) in environment protection.

The effects of different beverage intake on blood components during exercise under high-temperature environment.

Assessing the distribution and protection status of two types of cool environment to facilitate their conservation under climate change.

Jephcott lecture. Protection of the environment: the human dimension.

Writing for publication: institutional support provides an enabling environment.

Effect of different test situations on creativity scores.

Conservative Tests under Satisficing Models of Publication Bias.

How Anxiety Leads to Suboptimal Decisions Under Risky Choice Situations.

The new ICRP concept of person dose related to the exposure for radiation qualities used in industrial radiography.

[Warming-up under cold environment].

Publication, publication, publication.

sodium fluoride rinses under different salivary flows in vitro.