|Draft Recommendations of the International Commission on Radiological Protection (02/276/06 - 05 June 06)
Comments from Switzerland
The document presented for consultation has been studied by the Swiss authorities responsible for radiological protection and by the Federal Commission on Radiological Protection and Radioactivity Surveillance.
The Swiss radiological protection authorities are pleased at the considerable progress which has been made since the previous version of the recommendations was published. In particular, they are pleased to see that many of the comments they made at the end of 2004 have been incorporated into the new project.
The harmonized approach to radiological protection presented in the recommendations is based on general principles which are both well established and transparent. It distinguishes clearly between the different types and categories of exposure and operates on two complementary levels – the source and the individual. Overall it represents a true evolution and a firming up of the concepts involved and justifies a revision of the ICRP’s basic document.
Since the document is destined to play a central role in radiological protection at the international level in the years to come, however, it still needs some further improvements.
Suggestions for improvements
1. Consistency of the recommendations
The ICRP’s recommendations should form a unified whole; the document needs to be consistent within itself and self-contained. In this context the document should not:
• refer (except in the explanations given in the introduction) to the ICRP’s Publication 60 by giving a detailed description of the differences;
• reiterate the proposals made in the operational documents (such as the BSS) since their content ought to be derived from the ICRP’s recommendations and not the other way round (cf. for example paragraph 311).
2. Estimation of the radiological risk
With respect to the risk factors for induction of cancer, the ICRP’s arguments in favour of introducing the DDREF are not very convincing, even if Annex A is taken into account. Introducing the elegant Bayesian theory to account for uncertainties does not essentially change this situation. Moreover, the introduction by BEIR VII of a lower factor (1.5) demonstrates the lowering tendency of this type of correction. Given the current state of knowledge and the general principle that caution should prevail, it seems reasonable simply not to introduce this factor.
The introduction by ICRP of the multifactorial diseases in the assessment of genetic effects is a new and positive achievement. However the fact that the assessment of genetic risk is limited to exposure over the first two generations, in contrast to the approach taken in the past, is in itself surprising. The motivation for this decision is debatable and difficult to justify to the public. In addition, this restriction is at odds with the precautionary principle and also with the principle of sustainable development.
3. LNT hypothesis
Given the current level of knowledge, the LNT hypothesis adopted by the ICRP is certainly the only reasonable approach. It is also compatible with the results of studies of the effect of radiation at the molecular level: a single particle is capable of inducing cancer.
It is regrettable that the ICRP implicitly questions this hypothesis every time its application is discussed. In this way deaths become “hypothetical” and estimating their number becomes unreasonable (cf. for example paragraph 147). Adding a small risk of dying to a large number of individuals leads mathematically and logically to a certain number of deaths. If a linear non-threshold relationship is postulated, this estimate is correct. It is not possible to use the LNT hypothesis yet not accept its consequences.
4. Dose limits
Abandoning the DDREF (see point 2 above) would mean putting the dose limit for professionals at 10 mSv annually. It seems that the ICRP does not envisage taking this step in its next recommendations. However, it is regrettable that the opportunity presented by the new recommendation has not been taken to eliminate the annual dose limit of 50 mSv providing a mean annual exposure of 20 mSv over 5 years is not exceeded. The experience gained since the de facto reduction of the limit from 50 mSv/year to 20 mSv/year in 1990 ought to be sufficient to eliminate the margin which was perhaps necessary at the time to ensure a smooth transition. The Swiss radiological protection authorities feel that the annual limit of 50 mSv is not acceptable for normal situations and should therefore be eliminated.
5. Dose constraints
The introduction of dose constraints as a fundamental element of radiological protection is a Copernican revolution. Its propagation as a fundamental parameter (paragraph 184), perhaps on a level with dose limits, implies that the legislation governing radiological protection will have to be reconsidered in the future.
The Swiss authorities have considered the impact of this development in full. They feel that it would be useful to define the concept in more detail in order to facilitate its implementation. In particular, it would be useful to create a direct link between constraint and risk and to define the hierarchical position of this parameter in the general structure of radiological protection. We feel that this is not a parameter that has been derived from the dose limit (primary parameter) but one that is on the same level. It would equally be useful to outline the way in which the idea of constraint is intended to be used in practice, in particular in workplace protection.
Finally, we would like to thank the ICRP for the opportunity to comment the draft recommendations. The chapters on dosimetric quantities and on medical exposure meet with our full approval, particularly the introduction of diagnostic reference levels, which we are planning to incorporate into our legislation in the near future. In contrast, the chapter on environmental protection looks very much like “work in progress” , difficult to incorporate into either the legislation or the everyday practice of radiological protection. We suggest waiting until the concepts mentioned here have been finalized before propagating them and, accordingly, removing chapter 10 from the recommendations.