2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by George Hunter, Scottish Environment Protection Agency
Commenting on behalf of the organisation

SEPA’s DRAFT COMMENTS ON THE ICRP’s DRAFT 2005 RECOMMENDATIONS SEPA welcomes the opportunity to comment on the Commission’s draft 2005 recommendations. Our overall impression is that the proposals would benefit from a clearer, more coherent presentation; in places the document is difficult to understand, and there are many instances of ambiguity or contradiction. It may well be, that this ambiguity has arisen from the commendable intention to make this draft more accessible to a wider audience. However, it is arguable that this draft does meet the needs of stakeholders with NO expertise in this field, in that it assumes a great deal of prior knowledge and familiarity with the subject, nor does it meet the needs of those with responsibility for implementing the Commission’s recommendations, as it lacks the detail necessary for informed discussion and comment. We are aware that the foundation documents, on which this draft is based, have yet to be finalised. Our experience has been that, without the benefit of the foundation documents, we have found it difficult to evaluate these draft recommendations in any detail. We would, therefore, welcome a further opportunity to comment on revised recommendations that are presented with sufficient clarity and supporting documentation to enable informed debate. In any further consultation, we would urge the Commission to ensure that all stakeholders are provided with the means to engage fully. A useful model for relaying technical information to audiences with various levels of awareness of specific issues is that developed by the organisation ‘GreenFacts’ (http://www.greenfacts.org). GreenFacts provides an information and educational website on environmental issues in which the information is presented in several layers, beginning with the most basic description of the issue where terminology is defined, and progressively including more technical information within each of the subsequent layers. We believe this format provides a valuable approach for information provision that acknowledges the different needs of stakeholders. We have set out our main comments on key themes below, followed by specific comments on the text. PRINCIPLES OF RADIATION PROTECTION SEPA’s primary concern, as the competent authority in Scotland for the protection of the public from controllable sources of radioactivity in the environment, is a loss of clarity over the principles of radiation protection. In particular, we are concerned that the statement in paragraph (133), “The most fundamental level of protection is the source-related restriction on individual dose called a dose constraint” appears to give the principle of limitation more importance than the principle optimisation in the radiation protection framework. We believe the principles of justification, optimisation, and limitation were set out clearly in ICRP60, and are now well established in European legislation, (Directive 96/29/EURATOM). In ICRP60, justification of a practice is the primary principle for radiation protection, requiring that the overall benefit from a practice outweighs any radiation detriment to exposed individuals. Optimisation of the practice then requires exposure, or the likelihood of exposure, of individuals to controllable sources to be kept as low as reasonably achievable (ALARA). Limitation establishes the need to define maximum acceptable bounds to exposure of individuals to controllable sources. The concept of ALARA was strongly elucidated within ICRP 60, and it was clear that optimisation provided for the best achievable level of protection to exposed individuals, while limitation specified maximum dose levels above which exposure is unacceptable. Rather than describing the dose constraint as “the most fundamental level of protection”, perhaps it could be better described as the “the basic minimum level of protection”. The change in emphasis in these proposals might simply be an artefact of presentation, but SEPA’s interpretation is that the Commission’s proposals appear to weaken the established system of radiological protection, rather than strengthen it, and to downgrade the principle of optimisation from that of a main driver to that of a complementary consideration. CONSTRAINTS These proposals inspire confusion over current understanding of the distinction between statutory limits, and constraints. It has been UK Government policy for the past decade, to set dose constraints, in line with ICRP 60, at levels lower than the statutory annual dose limit of 1 mSv for public exposure to all controllable sources. We do not find the apparent loss of differentiation between limits and constraints to be helpful. Those maximum constraints proposed by the Commission are, numerically equal to the limits recommended in ICRP60; in this context, the proposals could be construed as a relaxation of radiation protection standards. There is therefore, a need for greater clarity in the Commission’s proposals. This might be helped by explicitly restating the limits set out in ICRP 60, rather than only referring to them. It is also not clear whether these constraints are equally applicable to retrospective assessments of dose actually incurred by individuals, and to prospective assessments of dose likely to be incurred as a result of proposed activities. Another matter of concern is that the table of constraints (Table 7) blurs the distinction between controls to be applied in normal situations, and those to be applied in emergency situations. PRACTICES AND INTERVENTION The distinction between normal situations and emergency situations is further blurred by the removal from these proposals of the concept of intervention. The definition of a practice, in paragraph (17), refers only to deliberate human activity increasing, or maintaining radiation exposure. Under ICRP60 there was a clear distinction between the protection framework that applied to routine operations, or practices, and that which applied to interventions in emergency situations. This distinction appears to have been removed in these proposals, and it is not clear why, or what the justification is for such a move. Those paragraphs that deal with emergency situations in these proposals [(20), (21), (22) & (23)] lack clarity. Indeed, they seem to make certain intervention situations into practices. EXCLUSION OF RADIATION SOURCES SEPA supports an international agreement upon a single set of radionuclide specific levels for exclusion, and a graded approach to regulation. However, we consider that the level of regulation should be proportionate to the assessed risk of a specific situation rather than the hazard, as proposed in paragraph (28). We consider that the recommendations must also acknowledge the scope for national authorities to be able to grant exemptions for certain practices from all or, some of the provisions of the regulatory system, which entail use or, disposal of radionuclides at concentrations or quantities above exclusion levels. A system of exemption provides a degree of control, without excessive bureaucracy, over uses of radioactive substances where there is a clear benefit from such use whilst ensuring continued protection of the environment and the public. The absence of 3H and 14C from the radio nuclides in Table S2 is difficult to understand. We are also concerned that the values for exclusion activity concentrations are single values, with no account taken of physical form, speciation, mobility or ease of uptake. PROTECTION OF THE ENVIRONMENT SEPA’s understanding is that the Commission’s work in this field is very much in the early stages of development. The Commission consulted, prior to its issuing of Publication 91 last year. In this context, we are not convinced that it was appropriate to include what constitutes very much a “work in progress” in these draft recommendations. However, we hope the Commission will find the following comments useful. It appears to SEPA that the Commission is developing its system within the context of, an operating assumption that there is no unacceptable harm being incurred by non-human biota as a result of discharges to the environment. The evidence available to date may support this assumption, but it must be acknowledged that such evidence is not sufficiently comprehensive to rule out the potential for harm in some circumstances. Given this lack of absolute confidence, we are concerned that the system being proposed by the Commission is not sufficiently informed by sound ecological, and environmental science to enable it to stand up to the scrutiny that will be required for it to achieve credibility outside the radiation protection community. It is arguable that paragraphs (243) & (244) would be better placed in reverse order i.e. that there is “a need for the Commission to develop a common scientific basis and approach for relating exposure to dose, and dose to effect, for all living things.”, followed by “there is a need to explore further the nature of the ‘risks’ that may apply to other species, how such risks may be quantified, and thus how it can be positively demonstrated that they are, indeed, ‘…not put at risk’.” There is an over simplification of the environment and its components implicit in paragraph (245). SEPA believes that it is fundamentally impossible, given such a limited list of reference organisms, to adequately assess risks to all organisms. There will be innumerable species with very different lifecycles and exposure characteristics to those of the reference organisms. How then can risks to such species be assessed by relating data to the reference organisms? The dangers of extrapolating between apparently similar species will also need to be addressed. There is an assumption that radioactive contamination will affect similar species in similar ways, an assumption which does not withstand analysis. An example of this is the radical difference in response characteristics to polychlorinated biphenyls (PCBs) in otter, and in mink, both semi aquatic carnivores of the genus Mustela. It should also be recognised that similar species in different climatic zones may have very different lifecycles. For example, the development of amphibian young from egg to adult takes place over a period of some weeks in temperate zones, but only a matter of days in equatorial zones. What effect might these developmental differences have on sensitivity to ionising radiation? These proposals regarding Reference Organisms would benefit from the input of more up-to-date ecological thinking. The Reference Organism selection criteria in paragraph (B13) appear to be based on value judgement and an oversimplified view of the environment, rather than on a scientifically rigorous assessment of an organism’s importance, or the extent to which an organism can constitute a sentinel species in its ecological compartment. The Commission would do well to update its approach in the light of recent developments in the ecological description and understanding of the environment, such as is embodied in the concept of functional guilds. There is no sound scientific reason why an overlap with “toxicity test” organisms is desirable, as suggested in (B13). The choice of organisms for use in ecotoxicological testing is governed more by the ease with which they can be maintained in laboratory conditions than by their validity as representative organisms of those found in aquatic and terrestrial ecosystems. Rather than propagate a system based on experimental convenience, it would be desirable to take this opportunity to define a set of Reference Organisms on a sound ecological basis. The specific set of Reference Organisms proposed by the Commission is too limited in scope to be able to demonstrate protection of the environment. While SEPA recognises the need to explain the basis of a system of environmental protection to the public, and decision makers in terms concomitant with the audience’s level of understanding, the need for simplicity should not itself become a major driver behind the choice of Reference Organisms. We are particularly concerned that the set of Reference Animals and Plants referred to in (B15) has significant omissions. All of the terrestrial animal species chosen are very short-lived in their natural environments, and will therefore accumulate to a lesser extent in their lifetimes the radiation-induced effects referred to in (B16) than will long-lived species. A critical omission is that of any large long-lived predators. The position of such organisms in their food-chains means that they are vulnerable to bioaccumulation of other non-radioactive pollutants, as has been demonstrated with e.g. persistent organic pollutants and mercury in polar bears and in seals. While we appreciate that there will be considerable difficulties, both experimental and ethical, in determining the extent to which bioaccumulation of radio nuclides occurs in long-lived predators, such difficulties cannot in themselves be a reason for their omission from a set of Reference Organisms. At the other end of the scale, there is no reference to phytoplankton, the primary producers in the aquatic environment, or to mycorrhizal fungi, organisms upon which all arboreal ecosystems depend. Consideration also needs to be given to the protection of endemic, or island, species i.e. those that exist in only one area. Finally, we endorse the need to assess the impact on individual organisms, but consider that there is a need for a framework to ensure protection of populations and ecosystems. SPECIFIC COMMENTS ON THE TEXT OF THE PROPOSALS (6): We are not persuaded by the argument that “there has been a move from the utilitarian approach of ‘the greatest good for the greatest number’, to one with more concern for the ‘individual’,”. This is presented as a statement of fact, when it is actually an opinion, and one which is not necessarily based on consensus within the international community. (51): The proposal to move to a new special name for the unit of radiation weighted dose is a welcome one that will help avoid confusion with effective dose. (88): Given the increasing life expectancy of people in developed countries, are the commitment periods of 50 years for adults and 70 years for infants and children sufficiently long? (91): The ALI values have been a useful tool, and it would be helpful if the Commission resumed provision of these values. (113): This statement appears to open the door to the future reduction of risk estimates to take account of improved cancer survival rates. We believe that this is an appropriate way deal with risk and detriment from radiation exposure. (137): First mention of “risk constraint for potential exposures” – what does this mean? (145): Public exposure is also incurred as a result of a range of uncontrollable sources. (171) & (172): The stated requirement for the characteristics of a critical group to be derived from a “sustainable” group is questionable. From SEPA’s perspective, with a duty to protect the public from all controllable discharges of radioactivity to the environment, there is a need to ensure that the characteristics of the critical group are responsive to changes in the make-up and behaviour of exposed populations. The Commission may also wish to give some thought to the status of the critical group concept in a radiation protection framework intended to place greater emphasis on protection of the individual. (173): We are not persuaded that the move from age-specific dose coefficients to age-averaged dose coefficients is appropriate. Such a move is itself inconsistent with a system intending to place greater emphasis on protection of the individual, and does not fit with the European Union’s Environmental Health Strategy which identifies children as a vulnerable group. (195): We fully support this statement. (200): Collective dose remains a valuable concept, in that it provides a measure of radiation detriment to populations – this is a necessary consequence of the linear no threshold (LNT) hypothesis. The statement “a large dose to a small number of people is not equivalent to a small dose to many people, even if the two cases correspond to numerically equal collective doses” is a judgement that is not accepted by everyone, and it appears to run counter to the LNT hypothesis. There remains a need to optimise the exposure of wider populations, and these proposals do not provide clear guidance on how collective dose can be used to inform the optimisation process. (Chapter 11): This chapter would be more accurately named “Protection of Non-Human Species”. (B4): Very little is actually known about the impacts upon human health of the vast majority of chemical discharges to the environment.