2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by David Fenton, Radiological Protection Institute of Ireland
Commenting on behalf of the organisation

COMMENTS FROM THE RADIOLOGICAL PROTECTION INSTITUTE OF IRELAND ON THE DRAFT 2005 ICRP RECOMMENDATIONS Introduction The Radiological Protection Institute of Ireland (RPII) is the national organisation with regulatory, monitoring and advisory responsibilities in matters pertaining to ionising radiation in Ireland. The RPII’s role includes maintaining and developing a national laboratory for the measurement of levels of radioactivity in the environment, and assessing the significance of these levels for the Irish population. In addition the RPII is responsible for implementing legislation governing all sources of ionising radiation in workplaces, including radon. In this latter role the RPII is aware of the important role ICRP plays in shaping new legislation and for this reason it gives careful consideration to any proposed new ICRP recommendations. The comments below are focussed on the possible impact of the draft Recommendations on these two key areas of the RPII’s work. General Comments 1.ICRP recommendations form the basis for legislation and can drive legislative change. The RPII therefore welcomes the approach adopted by the ICRP in consulting and seeking the views of stakeholders when formulating their recommendations. 2. The RPII recognises the important role and the contribution the ICRP has made in advancing the science on the biological aspects of radiological protection and in the quantities used in radiological protection. It therefore welcomes the new recommendations which consolidate the scientific information gained since ICRP 60 was published in 1990. 3. While clearly the draft 2005 recommendations need to stand alone, it is our view that better linkages between the 1990 recommendations and the draft 2005 recommendations would improve the reader’s understanding of the new proposals. 4. The RPII agrees with the ICRP’s observations made in paragraph S3 of the Summary of the Recommendations and again in paragraph 156 of Chapter 6 that “no major problem has been identified with the practical use of the present system of protection in normal situations”. This system “has led to an overall reduction in occupational and public doses over the past decade”. In light of this, while we welcome the new scientific information in the draft recommendations, it is not clear why a change to the international framework of radiological protection is being proposed. The proposed system seems to largely involve a change in terminology only and it is not clear how protection will be improved. For example assigning a new meaning to the term “dose constraint” and placing an increased emphasis on this term over the “dose limit”. There is not a clear indication of the problems that are likely to be solved by the new recommendations and in light of this it seems that a change to the present system is not demonstrated. 5. The RPII is concerned with the treatment of the concept of justification in the draft recommendations. Justification has been an important principal of radiation protection for many years. It is a concept that is now well understood and adhered to in the operation of the current system of radiological protection. While we agree that justification is not solely a radiological protection issue, it is our view that justification on radiological protection grounds is a pre-requisite for a broader justification and needs to be treated in this way in the text. This point is repeated in the specific comments below. 6. The purpose and scope of the recommendations are not clearly defined and essential parts emerge only later in the text. For example previous recommendations in ICRP 26 and ICRP 60 dealt with occupational exposure to ionising radiation. The new recommendations deal with exposure to controllable sources of which radon in homes is now included. However this does not become clear until Section 6.4, paragraph 178. An earlier statement of this in the Scope and Summary of the Recommendations would be beneficial. 7. The meanings of many of the terms used only become apparent when reading through the text. Clarity of the document would be aided by a list of definitions or a glossary of terms used. A list of the terms that might be included in such a glossary is given in the appendix. 8. The RPII agrees with and welcomes the introduction of the new unit “radiation weighted dose” to replace “equivalent dose”. We look forward to the name of the new unit. The introduction of this new unit will help the general understanding of the concepts of radiation protection. Specific Comments Chapter 2. The aim and scope of the Commission’s recommendations. 1. Radon in homes is classified as a controllable source section 6.4 paragraph 178 and falls within the scope of the recommendations. While paragraph 22 refers to natural sources radon is not specifically mentioned. A clear statement to this effect could usefully be made in section 2.2. 2. As mentioned in the general comments the apparent weakening/moving away from the justification principal is unhelpful. Paragraph 18 of Section 2.2. states that justification is largely outside the scope of the recommendations. Paragraph 20 however says that the system of radiological protection proposed by the Commission is aimed at practices declared to be justified. This seems contradictory but could be resolved by a statement reaffirming justification as an important principal of radiological protection. Chapter 3. Quantities used in Radiological Protection 1. Table 3 in paragraph 81 of section 3.4.2. It is unclear what quantity is being described in the third column. The same table is also repeated in table S4 of paragraph S17 of the Summary of the Recommendations. Chapter 4. Biological Aspects of Radiological Protection 1. The RPII did not review this chapter and therefore offers no comment on it. Chapter 5. The General System of Protection 1. As mentioned earlier justification is an important principal of radiological protection. The framework for the justification of proposed and continuing practices outlined in ICRP 60 is well understood and is adhered to in the operation of the current system of radiological protection. In the absence of strong reasons, it seem unwise to weaken the justification principal. A better approach could be to reaffirm the recommendations of ICRP 60 on justification. 2. Paragraph 132 of section 5.2. In this paragraph, the term “representative individual” is used. It would be helpful to define “representative individuals” . From paragraph 133 it would seem that they are representative of the most exposed individuals. Clarification would also be helpful in paragraph S5 which refers to the most exposed individual and does not mention representative individuals. 3. In figure 2, paragraph 135 under the caption “the worker is protected” the same symbols should be used to represent radiation exposure. As it is currently depicted an impression could be formed that there are two types of radiation exposure possible. The trefoil symbol used should also be consistent in both captions. 4. Section 5.3.1 paragraph 143 describes “occupational exposure as exposure incurred at work as a result of situations that can reasonably be regarded as being the responsibility of the operating management”. It is unclear if radon exposure in above ground workplaces is included here. If it is, then it should be explicitly stated as such. Chapter 6. The Commission’s Required Levels of Protection for Individuals 1. The RPII agrees with the ICRP’s observations in paragraph 156 of Chapter 6 that no major problem has been identified with the practical use of the present system of protection in normal situations and that the system has “led to an overall reduction in worker and public doses over the past decade”. In light of this it is not clear why a change to the international framework to system of radiological protection is being proposed. Without a clear indication of the problems that are likely to be solved by the new recommendations, it seems that a change to the present system is not warranted. 2. Paragraph 161 of Section 6.1 refers to sources used in practices that have not been judged to be frivolous. For the use of sources to be judged as frivolous their justification would have to be evaluated. For this reason, it would be helpful to include the principal of justification as set out in ICRP 60. 3. In Section 6.4, radon at home and at work is classified as a controllable source and recommendations for its treatment are set out in paragraphs 178 to 180. In Ireland, as in a number of other countries, the majority of the population receive most of their exposure to radiation from radon. For this reason, it is particularly important to RPII that the recommendations regarding radon and home and at work are easily explained within the overall system of radiological protection. While paragraphs 178 to 180 set out the policy in a clear way, it would be helpful if this was linked back more clearly to Sections 6.2 and 6.3. e.g some reference to exposure to radon in paragraph 164 would be helpful. In paragraph 180, it is stated that where radon levels are below the national constraint, doses from radon should not be recorded in the worker’s dose record. This seems to imply that where this is not the case, i.e. where radon levels are above the constraint, doses should be recorded. It would be useful to cover this point explicitly. As worker doses from practices continue to reduce, it is possible, at least in some countries, that exposure to radon would become the dominant source of occupational exposure. 4. In Chapter 6 a new meaning (when compared to ICRP 60) is given to the term dose constraint and more emphasis is placed on the dose constraint, as opposed to the dose limit. The concept of a limit is well understood in society generally e.g. speed limit etc., and from a regulatory perspective, and is conceptually easier to implement in a legal sense that a dose constraint. The present meaning and use of the terms dose constraint and dose limit should therefore be retained. 5. The intent of the provisions of Section 6.3.3 is to outline the measures to be taken to protect the unborn child. The title “the exposure of women” is therefore somewhat misleading. Another title along the lines “Protection during Pregnancy” might be more appropriate. 6. As outlined in paragraph 175 the present system does not make a distinction between the sexes in the control of occupational exposure. Under the present system additional controls are likely to be needed to protect the unborn child following declaration of pregnancy. With regard to women who might be pregnant, the policy is that the methods of protection at work should provide a level of protection for any conceptus broadly comparable to that provided for members of the general public. The draft goes on to state that “The Commission considers that this policy will be adequately applied if the mother is exposed, prior to her declaration of pregnancy, under the system of protection recommended by the Commission”. It is not clear what is meant by this statement – it seems to imply that women who may be pregnant should not be allowed to receive an exposure greater than 1 mSv before they might declare their pregnancy. It would be helpful to clarify this point. Notwithstanding these remarks there are a few difficulties that present themselves when considering how the proposed system might be implemented · the woman herself may not know she is pregnant for a number of weeks · an employer would not know if the woman is pregnant and in many cases is precluded from making such an enquiry. In that case it would be impossible to put in place the additional controls referred to paragraph 175 · if additional controls are needed for women who may be pregnant this might be viewed as discriminatory and might in some cases lead to the woman not been employed for certain positions · if the recommendation is to apply to women who may be pregnant it might undermine the woman’s entitlement to choose the time to declare her pregnancy. Chapter 7 Optimisation of Protection 1. Section 7.2 paragraph 201 introduces the concept of a dose matrix. This may be a worthwhile concept and might help clarify the concept of collective dose. However there is not enough information given in the draft text to judge the validity or otherwise of the dose matrix. A clear definition of dose matrix and worked examples would be beneficial. Chapter 8 Exclusion of sources from the Scope of the Recommendations 1. The RPII welcomes the quantification of the values below which it is recommended that radionuclides can be excluded from any system of protection. Specifying such exclusion values is likely to improve the present system of radiological protection in that it will make it clearer as to which sources and practices should not be subject to any form of regulatory control. 2. Section 8.1 paragraph 206, table 10 mention is made of U-238 and Th-232 decay series. However reference should also be made to the U-235 and Np-237 decay series either in the table or as a footnote to the table. This comment is also relevant to paragraph S12 where this table is reproduced. Chapter 9 Medical Exposure 1. The system that is proposed largely reflects the present system. This is welcomed. 2. Section 9.1.2 paragraph 219 discusses individual justification. As it is normally the referring physician who must perform the initial justification for the procedure the order in which the radiological practitioner and the referring physician are stated should be reversed. 3. Section 9.4 paragraph 227 while most diagnostic nuclear medicine procedures, particularly those involving Tc-99m do not require special restrictions to prevent patients travelling on public transport etc. others, such as those involving F-18 may warrant a risk assessment to be carried out. We therefore suggest that a new last sentence to paragraph 227 to read “Notwithstanding this general advice in all cases compliance with the relevant national constraints should be demonstrated”. Chapter 10 Potential Exposures 1. Section headings would be useful in placing context on the paragraph as well as making the chapter easier to read. 2. A worked example would support and help explain paragraph 230 on the probability of attributable death. Chapter 11 The Protection of the Environment 1. The RPII welcome the inclusion of a section dealing with the protection of non- human species. This should help create a more holistic system of radiological protection. 2. The RPII notes that the ICRP reaffirms its belief that if standards of environmental control are such that humans are protected then other species are not put at risk. While accepting this as the Commission’s view we feel it may need to be reviewed in light of (ongoing and finished) EU research projects in this area for example, a. Framework for Assessment of Environmental Impact (FASSET), b. Environmental Protection from Ionising Contaminants in the Arctic (EPIC) and c. Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) Appendix B Paragraph B27 1. Paragraph B27 states there are no agreed criteria or policies that explicitly address protection of the environment from ionizing radiation. We aware of efforts being made to address and promote this issue by the IAEA and the International Union of Radioecology. These efforts complement the OSPAR convention which has a significant component on disposal of radioactive material at the marine environment. Appendix to comments of RPII on draft 2005 Recommendations Terms that might to be included in a suggested “Glossary of the Terms used” in the draft 2005 Recommendations. The paragraph numbers where these terms are cited are given in parenthesis. Controllable source (S3) Dose matrix (201) Individual source (S6) Single Source (S5) Representative individuals (132) Most exposed individual (S5) Dose constraint (139) Dose Limit (139) Occupational exposure (142) Critical group (172) Probability of attributable death. (230) Hot Particles (239) Radiological Protection Institute of Ireland 24 December 2004