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Per Wikman, Philosophy Unit, Royal Institute of Technology, Stockholm, Sweden.
First, I want to thank the ICRP for providing this opportunity to comment on the forthcoming Recommendations. The new ICRP Recommendations have been a major topic of study for me in more than two and a half year in my present occupation of doing a PhD concerning Ethics of Radiation Protection. These comments are based on this work, and are presented for the Commission to consider.
My main impression of the development of the ICRP system of protection is that it is represents a thorough and responsible approach to many of the problematic ethical issues raised in radiation protection. However, I think that the present draft lacks clarity and coherence compared to the previous system. I believe that these deficiencies can be amended and my hope is that my comments can be of some use as an input in such a process.
My comments are focused on aspects of clarity and coherence and are divided into 1) the general system of principles, 2) dose constraints and 3) optimisation. Each of these sections starts with a summary and ends with suggestions.
1. THE SYSTEM OF PRINCIPLES
In the present draft there has been a major change in presentation from the previous Recommendations (Publication 60). However, the reason for this change is not clear. When examined it turns out that the new system of principles is, strictly speaking, equivalent with the previous. If the reason is to clarify the concept of dose-constraints, it is likely that such a clarification could have been achieved without reforming the whole system of principles. It can be argued that a clarification will be better understood, if stated in a familiar system.
Another problem with the present presentation is that it gives the impression that the emphasis now should be on dose constraints and that optimisation is not as important as before. If this really is the Commissions intention it ought to be stated more clearly. If there is no change in the importance of optimisation there is a potential of misunderstanding due to the increased emphasis on dose constraints. This is further augmented by to the loss of the previous explicit “system of principles”. My suggestion is that the description of an explicit system of principles is retained and that optimisation is emphasised in the forthcoming Recommendations.
1.2. EQUIVALENCE BETWEEN PREVIOUS AND NEW SYSTEM
The previous system, stated in ICRP’s Publication 60 (ICRP 1991), is based on three general principles combined in a coherent system:
B. Optimisation and dose constraints
C. Dose limits
From Publication 60 it is clear that the dose constraints and optimisation are lexically ordered, i.e. both are required but dose constraints have a higher priority than optimisation: “[optimisation] should be constrained by restrictions on the doses to individuals (dose constraints)“ (ICRP 1991, Paragraph 112). Thus, the order of priority in Publication 60 between dose constraints and optimisation is:
B1. Dose constraints
But this is exactly the same order of priority as the principles in the proposed new Recommendations. The principle of justification is removed in the present draft, but here I am primarily interested in optimisation and dose constraints. Thus, strictly speaking, the previous system of principles and the new are essentially equivalent. Although there is no change in the priority of the fundamental principles of protection, there have been substantial changes in the presentation in the new draft.
1.3. CHANGES IN THE NEW RECOMMENDATIONS
One important change in the new Recommendations is that the principles of protection are not described as a coherent system of principles. This is very different from Publication 60, where it is stressed, “It is important that the basic principles should be treated as a coherent system. No one part should be taken in isolation. In particular, mere compliance with dose limits is not a sufficient demonstration of a satisfactory performance.” (ICRP 1991, Paragraph 114).
Another difference is the increased emphasis on dose constraints and the decreased emphasis on optimisation. This is also shown by the number and length of paragraphs discussing dose-constraints compared to optimisation.
1.4. WHAT ARE THE REASONS FOR CHANGES?
The Commission has previously stated that the reason for the new Recommendations is the need to “clarify the meaning and the use of the constraint.” (ICRP 2003, p.130). And the draft states that the new system “is to be seen as a natural evolution of, and as a further clarification of, the 1990 Recommendations.” (ICRP 2004, Paragraph S4)
This is understandable if the previous Recommendations have not been fully understood or implemented. However, as argued above, it should already be clear from the previous Recommendations that dose constraints are lexically prior to optimisation. Also, it seems that such a clarification could have been made without the major changes introduced in the current presentation and that a clarification of the concept of dose constraints are likely to be better understood if stated in a familiar system.
1.5. PROBLEMS WITH THE CHANGES
The principle of optimisation has the lowest lexical priority; this was already the case in Publication 60. Since optimisation has the lowest priority, there is a risk that the importance and the requirement of the principle is not appreciated or understood. The system of principles in Publication 60, ordered in the way it was, can be seen as a clever way of emphasising the importance of optimisation. This is amplified by stressing that the principles should be seen as a coherent system of required principles.
The present emphasis on dose constraints, combined with decreased emphasis on optimisation and the removal of the explicit system of principles lead to a loss of clarity regarding the requirement of optimisation. The point is simply that it is unnecessary to put further emphasis on dose constraints than what is needed to make the intended lexical priority clear. But this should already be clear from the description in Publication 60 (and if it is not clear, it could easily be explained). This gives the paradoxical consequence that an increased emphasis on dose constraints, if it is made for the sake of clarifying the concept of dose constraints, might instead lead to less clarity.
My suggestion is that
1) An explicit system of principles is retained, and preferably the presentation ought to be made in the previous system (justification, optimisation & dose constraints, dose limits). The main argument given by the ICRP for the changes in the new Recommendations seems to be to clarify the concept of dose constraints. This is not a good reason as a clarification could be made using the previous system, and a clarification is likely be better understood if presented in a familiar system.
2) Optimisation is further emphasised in the forthcoming Recommendations. The present draft makes it less clear that optimisation is a required principle. This is due to the combined impression made by the absence of a explicit system of principles, the increased emphasis of dose constraints, the lesser emphasis on optimisation and, most importantly, that the fact the optimisation already is the principle with the lowest lexical priority.