2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by Natalia Golnik, Radiation Protection Section, Polish Society of Medical Physics
Commenting on behalf of the organisation

Radiation Protection Section of the Polish Society of Medical Physics (affiliated to IRPA) International Commission on Radiological Protection through the WWW page for comments Dear Sirs, Radiation Protection Section of the Polish Society of Medical Physics (RPS PSMP) duly appreciates the invitation from the ICRP to discuss the draft of the 2005 Recommendations of the International Commission on Radiological Protection. Being aware of the importance and practical consequences of the Recommendations we collected opinions from the members of our Society, who all are qualified radiation protection experts, mostly involved in operational radiation protection but also in research and in regulatory issues of the radiation protection. The collected opinions were discussed during two workshops, organized on 21 October 2004 in Cracow and on 16 November 2004 in Warsaw. The comments presented below are based on the agreed conclusions of the workshops and on some comments sent to the Executive Council of the Society. Therefore, they do not include all the individual opinions of the members of the Society. Comments on the ICRP 2005 draft recommendations General comments 1. Comments on justification for the new Recommendations The 2005 Recommendations were prepared in the time when the previous, 1990 Recommendations were only fairly recently implemented by national regulations in several countries and their practical implementation is not completed, even in developed countries. Taking into account the need for stability in international and national regulations, the RPS PSMP underlines that the implementation of the 2005 Recommendations would need a strong scientific justification for the proposed changes in the general system of protection. In our opinion there is no such justification provided for the 2005 Recommendations. Moreover, there is no indication of the promised simplification and increase in transparency. Basing on these arguments, the RPS PSMP concluded that there is rather a need for an addendum to the ICRP 1990 Recommendations than in a new Recommendations. The addendum could consolidate all the advice included in and developed since 1990, as well as other issues important for the evolutionary improvement of the radiation protection. However, the addendum should not trigger any inevitable process of the development of the new national regulations. 2. Comments to the Section 3 "Quantities used in radiological protection" 2.1. As mentioned in the Summary, the main part of the Section is updating the weighting factors in the quantity effective dose. The use of continuous function for defining radiation weighting factors, the updating of the function and the lowering of the radiation weighting factor for protons reflects the scientific opinions and were expected by the experts from our Society. However, several of them pointed out that the 2005 Recommendations do not give any clear recommendations concerning the radiation weighting factors for complex radiation fields with unknown composition and broad energy spectrum. The recommendations (e.g. the use of the Q(L) relationship) should be given for the following external radiation fields: ƒ{ - radiation, for which the value of wR is not defined in the Table 2 ƒ{ - radiation with unknown composition and energy spectrum ƒ{ - any mixed radiation with considerable contributions of particles with energy above 100 MeV. 2.2. The Polish Society wishes to emphasize its view that the concept of radiation weighting factors, unfortunately moved the radiation protection system a step away from science, comparing with the concept of the quality factor as a function of LET (ICRP 26) or lineal energy (ICRU 40). The system based on the concept of the dose equivalent was simpler, more coherent and could offer the same level of protection, provided that the values of the dose limits and the Q(L) relationship would be properly updated. 2.3. It seems, that the change of the name equivalent dose to radiation weighted dose will not solve the problems of confusion with the term dose equivalent, because the problem lies in the complicity of all the system of radiation protection quantities, not only in the name. Also the use of the unit sievert (Sv) is formally improper both for equivalent dose and effective dose. This unit was accepted withinin the SI as a special unit of the dose equivalent. Other quantities expressed in sieverts are ambient dose equivalent, directional dose equivalent, personal dose equivalent, and organ equivalent dose. The radiation weighted dose and effective dose are not included to the list. The less important comment is that it would be extremely difficult (if possible) to translate the term radiation weighted dose to Polish and perhaps also to some other languages. 2.4. In the Section 3, the quantities radiation weighted dose and effective dose are called sometimes "dosimetric quantities" and sometimes "radiological protection quantities" or "protection quantities" (e.g. in paragraph(59)). We propose to use the name "radiological protection quantities" and to reserve the term "dosimetric quantities" for physically defined, measurable quantities. 2.5. Paragraph (70) - There is no justification, neither reference for the use of equation (3). The values QT are not specified (no reference). There is no information which set of the values wT was used for the calculations of wR. There are also no resulting values of qE, neither the reference where they can be found. The quantity DE was not included to the set of quantities used in previous recommendations, therefore it should be introduced in the present document. 2.6. Paragraph (38) - The sentence "For protection purposes, it is assumed that these effects increase with increasing radiation dose, with no threshold. and that any increment of exposure above the natural background produces a linear increment of risk" and the sentence in the Summary (S6) "¡Kthere is presumed to be some probability of health effects even at small increments of exposure to radiation above the natural background" are confusing because they suggest to the reader that there is a zero risk of health effects (threshold?) at the natural background level, independently of the dose rate of the natural radiation. 3. Comments to the Section 4 "Biological aspects of radiological protection" 3.1. Unfortunately, the ICRP document "Low-dose cancer risk" was presented for discussion much later than the 2005 Recommendations. Therefore, the Polish Society resigned from preparation of its comments to the Section 4. 4. Comments to the Section 5 "The general system of protection". 4.1. There is a very important statement that "The most fundamental level of protection is the source-related restriction called a dose constraint¡K" (paragraph (133)). Unfortunately. there is no data or evidence presented to allow the reader to reach the conclusion that this new approach will be more understood or accepted by professionals or general public. Any considerable improvement of the radiological protection, neither any benefit for individuals were not clearly demonstrated, while the regulatory system becomes more complicated. Taking this into account, the Polish Society expressed the opinion, that the concept of the dose constraints from individual sources, that is considered to be useful in operational radiation protection, should remain within the optimization process. 5. Comments to the Section 6 "The Commission's required levels of protection for individuals" 5.1. Paragraph (165) Table 7 - Optimized emergency levels in international regulations (IAEA safety Series No 116, Vienna 1996) refer to the average over suitably chosen samples of the population, not to the most exposed individuals. For temporary evacuation this level equals to 50 mSv in a week. The maximum constraint of 100 mSv in a year for public evacuation, proposed by the ICRP, applies to the most exposed person. Similar problem exists with maximum constraint for countermeasures such as sheltering and iodine prophylaxis in emergency situations. Different approaches to this important problem in the IAEA regulations and in the ICRP recommendations do not facilitate the preparation of national regulations. Please try to harmonize your recommendations with international standards. 5.2. Last sentence of the paragraph (175) should be changed as follows: ¡§The working conditions of a pregnant worker, after declaration of pregnancy, should be such as to make it unlikely that the radiation weighted dose to the fetus will exceed about 1 mSv during the pregnancy. For a period before the declaration, exposure assessment should be performed". Justification: If a level of protection for any conceptus shall be comparable to that provided for members of general public, the exposure of the fetus before a declaration of pregnancy should be, as for as possible, also taken into account. 5.3. Comments to the Section 8 "Exclusion of sources from the scope of the recommendations" 5.4. In the paragraph 205 line 13 the "inter-Agency" should be replaced with "International.Atomic Energy Agency". It would be also better to replace (FAO et al) with (IAEA) in the line 14 because the mentioned Standards are world-wide known as the IAEA International Basic Safety Standards. Sincerely yours, Natalia Golnik Chairman of the Radiation Protection Section of Polish Society of Medical Physics