2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by Ted Lazo: Comment 4 of 5, OECD Nuclear Energy Agency (NEA)
Commenting on behalf of the organisation

NEA Comments on Specific Paragraphs (Submission 4 of 5) (180) The upper levels of 600 Bq m-3 for homes and 1500 Bq m-3 for workplaces can now be seen as Maximum Constraints, since the Commission regards these levels as providing the basic level of protection. The Commission now reconfirms its recommended maximum constraints for radon-222, which are set out in Table 8. It is the responsibility of the appropriate national authorities, as with other sources, to establish their own constraints and then to apply the process of optimisation of protection to arrive at the most applicable level at which to act in their country. All efforts should be made to reduce radon-222 exposures at home and at work to below the levels that are set. For occupational exposure below these levels (Comment: The phrase, as it was, seemed to imply that exposures below an optimised level should be Excluded. If any authorisation on these exposures is necessary, Exemption would seem to be the more applicable concept. If so, not applying the system to these exposures is in contradiction with paragraph 26 which suggests that such exposures remain within the system, although they are not regulated.) (deleted: the system of protection is not applied) and the resulting doses should not be recorded in the worker’s dose record. (Comment: If the numbers in table 8 are intended to be dose constraints, then one optimises below and thus this text is not correct. If these numbers are intended to be action levels, above which one takes action, then the text should be kept, but modified to account for miner’s doses which WOULD be recorded) For the public, there should be no attempt to reduce exposures further, and (as) they should not be (Comment: This same argument would also seem to apply to public exposures below levels set through optimisation. These would not be subject to regulatory actions, but there does not seem to be a need to refer to these as not being controllable) (regarded as controllable exposures) subject to regulatory actions. Table 8. Recommended Maximum Constraints for Radon-222†(Comment: These numbers seem to be too high, with respect to the latest epidemiological studies. These considerations should be put into the ICRP recommendations.) Situation Maximum Constraint Domestic dwellings 600 Bq m-3 Workplaces 1500 Bq m-3 †Head of chain activity level. (185) The Commission has concluded that the existing limits on effective dose that it recommended in Publication 60 continue to provide an appropriate restriction on total regulated doses in normal situations. The reasons for this are twofold: firstly, the Commission now emphasizes the use of constraints on single sources which are more restrictive than limits in normal situations; and secondly, the nominal detriment coefficients for both a workforce and the general public (Table 6) are more than 10% lower than those specified in the 1990 Recommendations. Within a class of exposure, occupational or public, dose limits apply to the sum of exposures from sources related to practices that are already justified in normal conditions. (Comment: This rationale would be useful earlier, because it probably applies to the selection of dose constraints also) For occupational exposure: ‘A limit on effective dose of 20 mSv per year, averaged over 5 years (100 mSv in 5 years), with the further provision that the effective dose should not exceed 50 mSv in any single year’ (paragraph 166, Publication 60). (Comment: This needs clarification if limits are meant to be used WITH a constraint of 20 mSv.) And for public exposure: ‘The limit should be expressed as an effective dose of 1 mSv in a year. However, in special circumstances a higher value of effective dose could be allowed in a single year, provided that the average over 5 years does not exceed 1 mSv per year’ (paragraph 192, Publication 60). Table 9. Recommended annual dose limits for individual organs or tissues Radiation weighted dose in Workers Public Lens of the eye 150 mSv 15 mSv Skin 1,2 500 mSv 50 mSv Hands and feet 500 mSv - 1 The limitation on effective dose provides sufficient protection for the skin against stochastic effects. An additional limit is needed for localised exposures in order to prevent tissue reactions. 2 Averaged over 1 cm2 area of skin regardless of the area exposed (Comment: The rationale for 1 cm2 has been revised to 10 cm2 in the United States based on work published by the National Council on Radiation Protection and Measurements. Suggest that ICRP consider incorporating this change.) 6.6 Complementary levels of protection of individuals (Comment: This section should be moved to the beginning of chapter 6 to show that limits, constraints and optimisation all go together) 7.1 The characteristics of the optimisation process (Comment: No mention of optimisation of Medical exposures in this section.) (189) Optimisation of protection is a process that is an important component of a successful radiological protection programme. In application, it involves evaluating and, where practical to do so, incorporating measures that tend to lower radiation doses to members of the public and to workers. An ICRP description of this procedure appeared in the 1990 Recommendations in Publication 60, where it is defined as follows: ‘In relation to any particular source within a practice, the magnitude of individual doses, the number of people exposed, and the likelihood of incurring exposures where these are not certain to be received (Comment: It should be noted that this early description of optimisation is already “Broader” than “classic” differential cost benefit analysis.) should all be kept as low as reasonably achievable, economic and social factors being taken into account’. The Commission now wishes to emphasise that conceptually, the optimisation of protection is broader, in that it entails consideration of the avoidance of accidents (Comment: Linking optimisation to accidents in this sense is new, and should have some text to provide explanation) and other potential exposures; it incorporates a range of qualitative and quantitative approaches and involves adopting a safety culture (paragraph 153). (190) The optimisation of protection is a forward-looking iterative process aimed at preventing exposures before they occur. It is continuous, taking into account both technical and socio-economic developments and requires both qualitative and quantitative judgements. This process must be systematic and carefully structured to ensure that all relevant aspects are taken into account. Optimisation is a frame of mind, always questioning whether the best has been done in the prevailing circumstances. It also requires the commitment from all levels of all concerned organisations as well as adequate procedures and resources. Both the operators and the appropriate national authority have responsibilities for optimisation. Operators design, propose and implement optimisation, and then use experience to further improve it. Authorities require and promote optimisation and may verify that it has been effectively implemented. (insert: The detailed requirements and good practice for optimisation should be elaborated by national-level bodies, public and private. International standards for implementation are developed by bodies other than the ICRP.) (Comment: In general, practical approaches to the implementation of the Commission’s recommendations are left to other organisations (national and international).) (194) The procedure for judging that no further dose reduction is reasonable should involve the comparison of a number of feasible protection options aimed at reducing the planned or potential doses to individuals. These options should first consider direct actions at the source, but should also include environmental actions. For exposures, the principle to be considered is whether these are as low as reasonably achievable. For the control of emissions to the environment, the ‘best available technology not entailing excessive costs’ principle may be used with due consideration to social and economic factors (insert: as one of the inputs in the optimization process) (Comment: This is added here to assure that BAT is not taken to be a complete substitute for optimisation). The resulting ‘optimal’ protection option would then be said to result in exposures to individuals that represent the best choice under the prevailing circumstances, (insert: taking health risks and social aspects into consideration.) (Comment: Health risks should be part of the consideration of BAT) (195) The basic role of the optimisation of protection is (Deleted: to foster a) (insert: complementary to) (Comment: This text is an attempt to clarify the relationship between safety culture and optimisation. A more detailed explanation, discussing the need to consider the specific nature of each situation, would be useful. Although the EGIR has no specific suggestion for this extra text, it is felt to be an important issue that merits clarification.) ‘safety culture’ as discussed in paragraph 153 and thereby to engender a state of thinking in everyone involved in the control of radiation exposures, such that they are continuously asking themselves the question, ‘Have I done all that I reasonably can to reduce these doses?’. Clearly, the answer to this question is a matter of judgement and necessitates co-operation between all concerned parties and, as a minimum, the operating management and the regulatory agencies. (196) The involvement of stakeholders, a term which has been used by the Commission in Publication 82 to mean those parties who have interests in and concern about a situation, is an important input to optimisation. While the extent of stakeholder involvement will vary from one situation to another in the decision-making process, it is a proven means to achieve the incorporation of values into decisions, the improvement of the substantive quality of decisions, the resolution of conflicts among competing interests, the building of shared understanding with both workers and the public as well as trust in institutions. Furthermore, involving all parties affected by the decision reinforces the protection culture and introduces the necessary flexibility in the management of the radiological risk that is needed to achieve more effective and sustainable decisions.(Comment: Stakeholder involvement is important, and is a key new issue, but lots more explanation is needed. The EGIR felt that the Commission should not say that Optimisation concludes when there is agreement among stakeholders. The Decider decides, taking into account various inputs, including those from stakeholders.) (201) The Commission now recommends the maintenance of the distribution of individual doses related to a given source in components reflecting the characteristics of the exposed individuals and the time and space distributions of exposures, relevant for the decision making process considered. This disaggregating process results in a ‘dose matrix’ which may be defined on a case by case basis. Furthermore, the components of this dose matrix can be individually weighted to perform appropriately the optimisation process. The weighting of these various elements will depend on the preferences and values of those involved in the decision making process, as well as on the feasibility of actions considered. Therefore, in the presentation of results, such case-specific weighting factors should be distinguishable from the elements of the actual dose matrix.(Comment: Should further describe the weighing that is discussed here. For example, what could be considered when weighting very small doses, or doses far into the future.) (Comment: Some members of the EGIR feel that collective dose can be a representation of collective detriment, while others do not accept the use of any collective detriment based on collective dose. There is some support for the use of collective dose as an indicator, particularly in selecting optimised protection for occupational exposure. In any case, the Commission should provide its views on collective detriment clearly, perhaps in this paragraph.) (202) Key matrix elements of such a matrix include the characteristics of exposed individuals, and the dose distribution in time and space. Aspects to be considered when establishing the importance of each matrix element in the decision-making process may include: -(Comment: It should be made clear that one can use the matrix for defining specific boundaries on the calculation of collective dose. For example, matrix elements can be chosen to characterise exposures for one generation only, for one specific population, or over a limited geographic area. This can, in certain situations, be a useful decision tool.)  Number of exposed individuals  Magnitude of individual doses  Dose distribution in time  Age and gender dependent risks as modifiers to dose distributions  Equity considerations (achieving a balanced dose distribution)  Real or potential exposure 8. EXCLUSION OF SOURCES FROM THE SCOPE OF THE RECOMMENDATIONS (204) Controllable sources and the associated radiation exposures fall within the scope of these recommendations. However, as stated in Section 2.3, the development of exclusion criteria would be beneficial in the practical application of protection and avoid the excessive regulation of radiation sources, both natural and artificial. The situation differs somewhat from the use of constraints and reasonable dose reduction by optimisation (See Chapters 6 and 7) but may be aided by their use. (Comment: Should say that practices and sources can be exempted when there is not more value in regulating) 8.1 Exclusion of quantities of artificial radionuclides (Comment: Note that DS 161 does not apply to effluents, and can thus not be applied as a definition for radioactive substance) (205) The starting point for consideration of values at which artificial radionuclides may be excluded from the scope of the Commission’s recommendations is the minimum constraint recommended in Section 6.2. (Deleted: this) The (Deleted: constraint) (insert: value) of 0.01 mSv (Comment: Here this number in its previous uses is called a constraint, but described as a number below which you do nothing. This is inconsistent with the Commission’s current definition.) in a year has been used extensively to establish the Exemption criteria used internationally and regionally. The inter-Agency Basic Safety Standards (FAO et al., 1996) and the Euratom Basic Safety Standards (Council of the European Union, 1996) have derived radionuclide-specific activities and activity concentrations, principally for users of small quantities of radionuclides. Recently, the IAEA has extended the use of the minimum constraint criterion to derive radionuclide-specific exemption activity concentrations for bulk materials (IAEA, 2005). Finally, the UN Food and Agriculture Organization (FAO) has revised its recommended activity concentrations in foodstuffs that can be traded internationally (CODEX, 2004). (Comment: . The EGIR believes that CODEX has not yet been approved, so the Commission should be careful with its references.) (209) The Commission proposes a set of exclusion values (insert: shown in Table 10) for the activity concentrations of natural radionuclides in materials (Deleted: Table 10). These levels were established from consideration of the distribution of concentrations of natural radionuclides in natural materials, representing a value towards the higher end of the generally observed range. In the UNSCEAR(The EGIR feels that the reference to UNSCEAR and the numbers here is wrong, the UNSCEAR numbers are much lower. See Table 15 of UNSCEAR 2000 Annex B.) (2000) report, activity concentrations of the naturally occurring radionuclides in food range from less than 0.001 up to about 0.1 Bq g-1. The exception is shellfish where 210Po, in the decay series of 238U can have activity concentrations of the order of 1 Bq g-1. Exposures from environmental materials and intakes of food and water, at these activity concentrations, would lead to individual annual effective doses of no more than about 0.2 millisieverts, which does not in the Commission's opinion imply an unacceptable level of exposure.(Comment: The EGIR feels that the dose levels that would result from the complete U series in equilibrium would be much higher than these values) (210) The Commission notes the recent work undertaken by the IAEA in the production of its report DS161 in which the exclusion levels for the uranium and thorium series and for 40K have been agreed internationally. These activity concentrations are shown in Table 10 and are recommended by the Commission as the levels below which materials do not enter the scope of its recommendations. Table 10. Recommended Exclusion Levels (Comment: During discussion with Prof. Clarke, he suggested that the Exclusion Levels in Table 10 could be each reduced by a factor of 10 to assure that they would be correctly applicable in all situations. The EGIR felt that such a reduction could be explored as an approach to address its other comments listed below. However, the implications of such a significant reduction would need to be well thought out and vetted before implementation.) (Comment: This table should be coherent with the recent IAEA work ( (Comment: The EGIR feels that the values proposed here are inconsistent with those proposed for radon in a previous chapter) (Comment: These numbers should be revisited. For example, EGIR members noted that using these numbers bananas can be excluded, but not K-supplements. Also, one member suggested that using these numbers for building materials could results in direct gamma dose - i.e. excluding radon dose - of on the order of 10 mSv/a. Even 10 times lower than this may be too high) Nuclides Exclusion activity concentration Artificial α-emitters 0.01 Bq g-1 Artificial β/γ emitters 0.1 Bq g-1 Head of chain activity level†, 238U, 232Th 1.0 Bq g-1 40K 10 Bq g-1 † For 238U and 232Th chains, this value also applies to any nuclide in a chain that is not in secular equilibrium excluding 222Rn and daughters in air which in all situations are controlled separately. 9. MEDICAL EXPOSURE (213) First and most important, the limitation of the dose to the individual patient is not recommended because it may, by reducing the effectiveness of the patient’s diagnosis or treatment, do more harm than good. The emphasis is then on the justification of the medical procedures (Comment: Should also emphasise that Optimisation is a key principle), (insert: and on optimisation of the implementation of patient exposures.) The recommendations do apply to the exposures of workers in medical services and members of the public. For both these classes, some changes of emphasis have to be considered. The constraints in Chapter 6.4, above, should apply to the workers and members of the public, but it should be recognised that some exposures have to be incurred in the care and support of patients. Members of the public may also be exposed in the course of caring for patients at home.