Recommendations

Introduction The Belgian Society for Radiation Protection (BVS•ABR) appreciates the opportunity given by the ICRP to its stakeholders to comment for a second time its proposals before these are published as new recommendations. A working group ad hoc was set up to analyse and comment the text and to make, where applicable, specific suggestions. The working group found the new draft much improved and welcomed in particular the preservation of the justification principle as one of the primary pillars of the system of radiological protection. As a general remark, the working group would appreciate a more precautionary approach by ICRP stating uncertainties and considering gaps in knowledge. The working group supports the extension of the optimisation approach into safety culture and would like to see this approach even further developed in the final text. The Belgian Society for Radiation Protection hopes that its focused comments and suggestions will be taken into account in the final text. 1 About the biological aspects of radiological protection (chapter 3) [11] Radiation-induced genetic risk In paragraphs 67 and 68, the 0.2% per Gy figure (risk up to the second generation) after continuous low dose-rate exposure over two generations is claimed to be essentially the same as that cited by UNSCEAR 2001, with reference to table 46 of UNSCEAR 2001. Note that this table gives the estimate from one-generation exposure (risk for continuing exposure being given in table 45). There is also a risk of confusion when speaking about the risk “up to” the second generation, suggesting that this is a cumulated risk and that it will be fully expressed in two generations. In the context of continuing exposure, table 45 gives the risk “in” the second generation, based on the evolution of the mutation component (see UNSCEAR 2001, paragraphs 505 and 437). With continuous exposure in subsequent generations, mutation component (and disease frequency) will continue to increase to attain a value of 1 at the new equilibrium (UNSCEAR 2001, figure V, p. 40). Finally, for obtaining the 0.2% per Gy figure, a reduction factor of 0.4 is applied to take into account the genetically significant dose in a global population: this is explained in the foundation document but not mentioned in the main text. Now, can we say that the genetic risk is practically limited to the two first generations? ICRP defends this view in paragraph 67 and supports it (in the foundation document) by radiobiological data suggesting that the major contribution to the genetic risk comes from multigene deletions expressing themselves essentially in the two first generations by multi-system developmental abnormalities and by the numerous uncertainties involved in the estimation of the long term genetic risk (“for tens or hundreds of human generations”). In fact radiation-induced DNA lesions are not always “multigene” deletions and the “short term” hereditary effects are not limited to multi-system developmental abnormalities and dominant diseases in the two first generations. When the chronic multifactorial diseases are left aside (as it was the case in UNSCEAR 1988 and 1993), the “equilibrium” risk coefficients are not significantly influenced by population changes over hundreds of years, but mostly by the selection effect for the most important component, i.e. the autosomal dominant/X-linked diseases, and this equilibrium is obtained after 5 to 6 generations (UNSCEAR 2001, figure V, p. 40). Even if we consider that the “weight” of the 2 first generations is preponderant, it would be by far more acceptable to take explicitly all the autosomal dominant/X-linked diseases into account, as it was done in the past. Finally, considering the numerous uncertainties involved for not estimating the long term genetic risk, it seems paradoxical to recognize that considerable uncertainties still exist in this field, while concluding that enough is known as regards the mechanisms of radiation-induction of genetic effects to allow ignoring the possibility of significant long term risks. The basic question is whether we know enough about possible long term radiation-induced genetic effects to close this matter and to take now the effect on the generations over the second as being zero. Suggestions: ICRP should more clearly underline that: - on comparable bases, the genetic risk has not decreased; - if the choice of a risk estimation for 2 generations only can be justified in the context of the calculation of effective dose for comparison with dose limits, long term genetic risks must be taken into account for judgments about continuous exposures affecting consecutive generations; - due to the numerous uncertainties, keeping gonadal doses ALARA is still strongly recommended (current sentence in paragraph 68 should be repeated in the relevant sections); - the current risk estimate is for a total population, not for a reproductive population. [12] Risk of in utero irradiation After irradiation during the pre-implantation period, generally considered as safe with regard to the radiation-induced risks, non lethal congenital malformations have been induced in animals, particularly (but not only) in those with a genetic predisposition to specific congenital malformations or with genetic disorders in the pathways of DNA-repair. Moreover, during the zygote-stage (about 1 day), there could be no threshold dose for the radiation-induction of congenital malformations in genetically predisposed animal strains. After irradiation during the organogenesis, more congenital malformations have also been induced in animals with genetic disorders, and there are similarities with the effects of chemical agents. In these cases, the cause of the congenital malformations may not be an increased loss of cells (classic deterministic effect) but rather the persistence of un-repaired or mis-repaired DNA-damaged cells (“teratogenically damaged cells”). Now, in humans, the same genetic susceptibilities probably exist: there are indeed families showing clusters of spontaneous congenital malformation. There are also in humans many genes implicated in the DNA-damage response and involved in the genetic susceptibility to cancer induction by irradiation; if the mechanisms are similar (persistence of mis-repaired DNA-damaged cells), it is plausible that human genotypes leading to cancer-proneness are also associated with a genetic susceptibility to the radiation-induction of congenital abnormalities (or more subtle tissue dysfunctions). Due to genetic susceptibilities, there could then be for some individuals a higher risk of radiation-induced malformations (or dysfunctions) or lower thresholds (or even no threshold at day 1?) and this risk could also exist during the “safe” periods of pre- and early post-implantation (when women are not aware of being pregnant). Although frequently assumed to be low, the frequency of these individuals is not known. This raises doubts about the “definite” and generalized character of the 100 mSv threshold dose for lethal, developmental or other detrimental effects after irradiation during the first trimester of pregnancy, currently applied by many as a practical criterion: this could be an unjustified simplification. Furthermore, 100 mSv to the foetus/embryo can be regarded as related with a very significant risk of radiation-induction of cancer! Suggestions: ICRP should: - more clearly underline the uncertainties in the evaluation of the risks after in utero irradiation and in the setting of reliable threshold doses; - emphasize that, due to the numerous uncertainties, keeping embryonic/foetal doses ALARA is still strongly recommended; - be cautious, especially in the medical field and in existing situations, and particularly avoid suggesting the “100 mSv” figure as a global and “definite” threshold for all significant effects. [13] Cataracts New data challenging the current dose threshold for radiation-induced cataracts are now available and sufficient for deriving already now appropriate conclusions. Suggestions: ICRP should: - be cautious and not wait for proposing up to date dose limits for the lens of the eye; - recommend appropriate dosimetry in critical practices as interventional radiology. [14] Non-cancer diseases Non-cancer diseases are discussed in paragraphs 86 and 87. Although the summary of the current scientific evidence in paragraph 86 seems adequate, the conclusion drawn in paragraph 87 is more questionable. While it is clear that no definite answer can be given regarding the shape of the dose-response at low dose and regarding the numerical values of possible threshold doses, that situation is somewhat comparable with the situation ICRP faced in the past regarding cancer induction: the uncertainties did not discourage ICRP several decades ago to adopt the LNT-hypothesis and the ALARA-approach. Suggestion: - ICRP should adopt a more precautionary approach and take explicitly this kind of risk into account in her judgements and protection recommendations, particularly in high dose situations as medical exposures and prolonged exposures. [15] DDREF The question of the DDREF is discussed in paragraphs 61 to 64. ICRP explains the arguments for and against a reduction of the DDREF and recognizes that maintaining a DDREF of 2 for purposes of radiological protection is the result of a broad judgement with both subjective and probabilistic uncertainty. One of the main arguments is the protracted character of the exposures incurred. However the ICRP system of radiological protection covers not only situations with chronic or protracted exposures but also high dose-rate situations like in medical radiology. Moreover, as several recent epidemiological studies point to a DDREF not significantly different of 1, the choice of a reduced value of DDREF would certainly be justifiable from a radiation protection perspective. Suggestion: - ICRP should adopt a more precautionary approach in relation with DDREF, especially in high dose-rate situations like in medical radiology. [16] Age and gender The differences of risks due to age and gender are hardly taken into account in the calculation of effective doses (single set of tissue weighting factors) and in the derived organ dose limitations. A way for better taking age and gender into account could be recommending the use of organ dose constraints where appropriate (for example for thyroid). Suggestion: - ICRP should consider recommending the use of organ dose constraints taking age and gender into account where appropriate (in particular for the thyroid). 2 About the dosimetric quantities (chapter 4) [21] Absorbed dose as defined under paragraph 95 is a non-stochastic quantity and therefore defined in a point. As such it can be determined by computation, but is not directly measurable. See ICRU33,I.B.: 'stochastic quantities can be experimentally determined, non-stochastic quantities (…) can, in principle be calculated, but (…) can be (experimentally) estimated as the average of observed values of the associated stochastic quantity' Therefore, in radiation protection mean absorbed dose (96) and averaged absorbed dose (99) is used. Suggestions: - Change in paragraph 95 'In principle, absorbed dose is a measurable quantity and primary standards exist to determine its value. The definition of absorbed dose has the scientific rigour required for a basic physical quantity' into: 'In principle, absorbed dose is not a measurable quantity, but this definition of absorbed dose has the scientific rigour required for a basic physical quantity.' - Explain the fact that, due to the fundamental stochastic nature of radiation interaction with tissue, e.g. in low doses of high LET radiation, most cells are not hit. The value of energy imparted in most individual cells is zero, but in the hit cell it will exceed the mean value by orders of magnitude. - Explain the difference between stochastic quantities and non-stochastic quantities (e.g. in annex A) and its relevance for radiation protection and e.g. general medical applications at the one side and e.g. microdosimetry and specific cases of radiation therapy at the other side. [22] The equivalent dose is a dose in a generic sense, but not in its physical sense. The unit of the equivalent dose is therefore chosen to be the sievert, and not the gray, but this is definitely not a J/kg, neither in a generic sense, nor in a physical or mathematical sense. An equivalent dose has nothing to do with a joule (J). The reason for this confusion is the choice for a dimensionless radiation weighting coefficient. Logically and mathematically correct is to choose for a dimensional radiation weighting factor while transforming the absorbed dose into an equivalent dose with the dimension of Sv/Gy: HT [Sv] = wR DT [(Sv/Gy).Gy] Suggestion: - Change the dimensionless radiation weighting coefficient into a dimensional radiation weighting factor with the dimension of Sv/Gy. [23] In paragraph 145 the special name for the collective dose quantity is proposed to be the 'man Sievert'. As radiation interactions have no human and/or gender like aspects, it is preferred to remain gender independent in the definition of units as is already the policy preferred by the Health Physics Society and by other authorities as well, and in accordance with paragraph 355 where the 'reference man' is replaced by the 'reference person'. Suggestion: - Change 'man Sievert' into 'person Sievert'. [24] To avoid aggregation of very low individual doses over extended time periods and wide geographical regions, limiting conditions need to be set in the definition of collective dose (148). Suggestion: - Please explain and specify E1 and E2 in equation 4.12. [25] In paragraph 105 the last sentence is not very clear: 'At very high neutron energies the radiation weighting factor decreases and approaches 2 to be consistent with the wR values for neutrons and protons' Suggestion: - 'At very high neutron energies the radiation weighting factor decreases and approaches 2 to be consistent with the wR values for protons' [26] Since male and female computational phantoms are defined, it seems more logical to define also gender-specific tissue weighting factors (117-120). The effective dose would still be averaged over the genders, and thus the same end-result will appear. These gender-specific tissue weighting factors will make the calculation of E clearer, and removes the need for explaining artificially gender-averaged weighting factors. Suggestion: - Change equation 4.5. [27] The quality factor Q will not be changed, thus the change in wR e.g. for neutrons will not be reflected in the operational quantities. Suggestion: - Include a paragraph explaining this, because this will be quite confusing for many people. [28] It is true that Hp(3) has rarely been used, but personal dosemeters for Hp(3) are relatively easy to construct with e.g. thermoluminescent dosemeters. So this is no reason to disregard Hp(3). Suggestion: - Delete in paragraph in 125 the last part of the sentence stating that no personal dosemeters are generally available that allow this to be measured. [29] Conversion factors to calculate the operational quantities starting from the fundamental quantities are available. These were calculated with anthropomorphic phantoms. Although nothing changes for the operational quantities, the conversion coefficients will be changed due to the introduction of the voxel phantoms. Suggestion: - Include a paragraph regarding the influence of this, i.e. should new conversion factors be calculated or will the difference be negligible. 3 About the system of radiological protection of humans (chapter 5) [31] About the definition of a source: chapter 5.1 is titled “The definition of a single source”, but in paragraphs 160 and 161 it is only discussed how the term “source” should be understood. No explicit definition of what the ICRP considers as a “source” is given. This could create some misunderstanding, especially as the term “source” could be confused with the use of “radioactive sources” or as distortions are possible, as mentioned at the end of paragraph 161. Suggestion: - Define explicitly in chapter 5.1 what is considered as a “single source” regarding the further discussion about the system of protection. [32] About the justification principle: the statements under (188-191) remain rather vague and unclear and as already mentioned in its previous comments, the working group does not understand the Commission’s motivation for making an explicit difference between medical and other exposures in relation to justification. For both medical and professional exposures a clear distinction can be made between the generic and a particular justification and the nuclear industry holds many examples of particular exposures that were judged not justified although the production of nuclear energy is generically justified. Suggestion: - reformulate paragraphs 188-191 by making a clear distinction between ‘generic’ justifications that fall under the responsibility of governments or governmental agencies and justification at the lower-level of specified procedures or the application of specified procedures, that fall under the responsibility of the operators or practitioners. No distinction between medical/occupational/public exposures needs to be made. [33] About the optimisation and the constraints: it is clear from the text of chapter 5.8 that the ICRP wants to put more emphasis on constraints, but the real purpose of this trend is not straightforward; is it only to avoid to create inequities resulting from the optimisation process, like mentioned in (185) and in (199), or are there other motivations (e.g. constraints can be seen as ‘reference levels’, in order to stimulate the optimisation process) ? Suggestion: - Summarize somewhere the real purposes that should be found behind the application of dose constraints. [34] About the dose limits: chapter 5.9 starts with the statement: "Dose limits apply in planned situations". From this, the working group understands that the limits are not applicable to emergency situations and to existing exposure situations. But the paragraph 240 mentions: "Dose limits do not apply in situations where the exposed individual is engaged in life saving actions or is attempting to prevent a catastrophic situation." This statement is then too restrictive and creates an ambiguity. Suggestions: - Replace the sentence in paragraph 240 by: "Dose limits do not apply for emergency situations and in existing exposure situations. The guidance given in section 11 would apply in such situations." - Clarify eventually in the definition of planned situations (162) that recovery operations after an emergency should be considered as a planned situation. 4 About the medical exposure of patients (chapter 6) [41] The current text of the chapter on medical exposures takes into account several of the remarks made on the previous version of the Recommendations. On some other remarks clarification is given. Suggestions: - The emphasis in the introduction (244) should not be limited to justification of acts applying ionising radiation but should also address justification of prescriptions and optimisation of as well procedures as protection. - Replace the last sentence of paragraph 246 by: Radiation exposures in medicine are not only limited by regulatory processes, but are also controlled by the physician, who therefore should be aware of the risks and benefits of the procedures involved. [42] Justification (246-250) The proposed distinction between generic justification and justification of procedures to individual patients is useful but could be more clarified in a proactive way. Generic justification in future will mainly address new technology developments and will have to consider also choices of most adequate techniques where cost-benefit consideration and value judgement will dominate. Generic justification became subject of multidisciplinary health advisory councils. Justification of procedures (6.1.2.) mainly concerns applied acts with ionising radiation. But in diagnosis particular prescriptions also require insight in radiation risks in order to be able to avoid unnecessary exposures. Medical physicists have demonstrated their important potential contribution to support the medical staff. Suggestions: - More adequate training of medical prescribers should allow them to implement justification as well. (246) (250) - Professional guidance including radiation protection concern is required to allow all physicians in medical imaging to take up their responsibility for justification as part of the regulatory requirement for protection of the patient (246). ICRP should specify the valuable supporting role of medical physicists in the processes of justification and of optimisation of patient protection, which can only succeed through a pluridisciplinary approach. [43] Optimisation Paragraph 251 should better underline that not enough attention has been given to optimisation in medical exposures. Whereas, numerous optimisation opportunities exist in particular for interventional radiology and for specific exposed groups, such as children exposed to CT and the foetus in nuclear medicine. Suggestions: - A major optimisation parameter, which allows dose reduction in digital imaging in particular, is to consider diagnostic capacity instead of maximum image resolution. - An integration of radiation protection procedures and reference levels in the process of optimisation as part of quality assurance should be underlined. [44] In paragraph 254 it is unclear why the values of the diagnostic reference levels should be left to selected professional medical bodies only. Suggestion: - In general, the Authorities should play an important role in establishing the values of the diagnostic reference levels in cooperation with the professional medical bodies and medical physicists. [45] Exposure of pregnant patients The Commission does not take into account recent results of animal in-utero irradiation experiments and states that there is no increased risk for prenatal death, developmental damage (including malformation, or impairment of mental development) resulting from in-utero exposure after correctly performed diagnostic procedures. Suggestion: - It is the working group’s conviction that regarding new experimental results, some precaution is needed in the recommendations, which should be less absolute. According to observation in animal models, effects as prenatal death and developmental damage could occur in the mSv range. [46] Patient Comforters (265)(266)(272)(275) The text of (265) is almost directly repeated in (266) and is hence superfluous. The working group does not agree with the Commission’s general point of view that the exposures of families and friends to patients discharged from a hospital have to be considered part of the medical exposure. Although the working group does acknowledge the problem in specific cases for non professional comforters and carers: not occupationally exposed individuals helping to support and comfort patients with informed consent. The fact that the Commission excludes young children, infants and visitors not engaged in the direct care or comfort of the patient (Publication 94) is reassuring to the working group. However the working group feels that this point of view should be given considerable more emphasis over the general statement found in (265) and repeated at the beginning of (266). Suggestions: - The exposure of relatives and friends in general should not be considered as medical, as these individuals are in most cases not properly informed. The correct information and the consensus of these individuals form the key elements to the discussion also whether or not the exposure to patients discharged from a hospital can be considered as part of the medical exposure. - At the end of paragraph 266, add 'dose limit' between the brackets: (i.e., be subject to a dose constraint and a dose limit) [47] Volunteers (267-268) The working group feels that there are several arguments to be found why the exposure of volunteers in biomedical research should not automatically be considered as medical exposure, although the working group does agree that a protection system with dose limits would not be practicable in this case. Amongst these arguments is the fact that protection of these volunteers cannot be governed by diagnostic reference levels due to the experimental character of the procedure, but should be based on dose constraints as is indicated by the Commission in (268). Additionally, there are ethical problems for not considering the exposures of volunteers, who are also occupationally exposed as part of their professional dose record. Suggestion: - The working group recommends only considering the exposures of volunteers in biomedical research as medical exposures under strict conditions and to register the dose of occupationally exposed persons in their professional records. [48] Medico-legal exposure (269) Suggestion: - The working group has the opinion that insurance companies and all other administrative interventions using ionising radiation for administrative reasons (such as border control of people) should respect dose constraints and dose limits for the public. Exceptions require an authorisation based on a justification procedure. [49] Release of patients after therapy with unsealed sources No specific attention is given to the release of patients treated with radionuclides with longer half-lives especially for palliative reasons and to protection considerations regarding corpses. Suggestions: - The control of radioactive contamination requires, besides dose considerations, particular attention for constraints. - The protection during different burial and incineration processes also requires optimisation efforts and constraints. - Delete in paragraph 271 'for thyroid cancer' just before (publications 73 and 94), because there are thyroid diseases other than cancer treated with radioiodine requiring special restrictions on nuclear medicine patients. 5 About the exposure to natural sources (chapter 7) [51] The suggested exclusion levels in paragraph 294 of 1000 Bq/kg for the uranium and thorium decay series and 10,000 Bq/kg for K-40 can in particular circumstances lead to significant controllable doses. Typical examples are: • The use of building materials in bulk amounts approaching the suggested exclusion levels can, according to Radiation Protection 112 of the European Commission (1999), lead to effective doses of more than 10 mSv/year to the inhabitants. • The conversion of an area contaminated with natural radionuclides approaching the suggested exclusion levels into a residential area can lead to effective doses to the inhabitants up to 10 mSv/year (e.g. a phosphogypsum deposit). From the above examples it is clear that the suggested exclusion levels cannot be generally applicable. Therefore they should be deleted from paragraph 294 or there should be a statement added in paragraph 294 "that there are circumstances where these exclusion levels could not be appropriate (e.g. bulk building materials, large contaminated areas)". Suggestion: - Delete the exclusion levels for naturally occurring radionuclides in paragraph 294 or add a statement that there are exposure situations where these exclusion levels could not be appropriate (e.g. bulk building materials, large contaminated areas). [52] The exemption of sealed sources in paragraph 295 with a dose rate less than 1 µSv/h at a distance of 0.1 m has especially to do with artificial sources and should therefore be placed in another chapter. The exemption in paragraph 295 of any amount of material with a dose rate less than 1 µSv/h at a distance of 0.1 m has no sense for alpha and beta emitters and questionable for gamma emitters. Suggestion: - Delete paragraph 295 entirely or transfer part of it to another chapter. In any case the exemption any amount of material with a dose rate less than 1 µSv/h at a distance of 0.1 m has no sense for alpha and beta emitters and questionable for gamma emitters. [53] Both the numerator and the denominator in the calculation of the conversion conventions for public and occupational exposures in ICRP 65 have been superseded (paragraph 299-301). Indeed, the numerator, which is based on the epidemiological studies of miners, was recently replaced by the pooled residential case control studies, as indicated in paragraph 297; while the denominator, the detriment associated with a unit effective dose, is superseded by table 2 on page 24 of this report. All the scientific evidences (numerator change, denominator change, dosimetric approach) point away from the ICRP 65 conversion conventions in the direction of the UNSCEAR conversion factor of 9 (nSv/h)/(Bq/m³) radon progeny exposure. Moreover, the average global exposure given in paragraph 283 of 2.4 mSv/year is calculated with the UNSCEAR conversion factor, which is 50 % higher than the ICRP 65 conversion convention for members of the public. Using the ICRP 65 conversion convention would result in an average global exposure of 2 mSv/year. For all these reasons it is only natural to replace the ICRP 65 conversion conventions by the long established UNSCEAR dose conversion factor. Suggestion: - Replace in paragraphs 299-301 the superseded ICRP 65 conversion conventions for public and occupational exposure by the UNSCEAR conversion factor of 9 (nSv/h)/(Bq/m³) radon progeny exposure. [54] It is not possible to assess the radiation dose from inhalation of thoron decay products by epidemiological means and therefore it must be estimated using dosimetric modelling. For consistency reasons it seems reasonable to adopt in paragraph 304 for thoron decay products the UNSCEAR dose conversion factor of 40 (nSv/h)/(Bq/m³). Suggestion: - Adopt in paragraph 304 for consistency reasons the UNSCEAR dose conversion factor of 40 (nSv/h)/(Bq/m³) for thoron decay products. 6 About the emergency situations and existing situations (chapter 9) [61] The chapter is well written, coherent and consistent with the other chapters and of a sufficient general nature that it doesn’t need severe amendments. There are a few issues however which would benefit from some further clarifications or explanations. Paragraph 339 states that […All accidents are different, as are the approaches of national organisations having responsibility for response to an emergency situation. The Commission’s general guidelines need to be translated into appropriate emergency plans by competent national authorities. The intervention levels given in those publications are now regarded as constraints.]. Paragraph 348 states that [Results of the optimisation process below the dose constraints will lead to intervention levels. The constraint represents the fundamental level of protection for the most exposed individuals and the level of dose or risk where action is almost always warranted. … The chosen values of constraints and intervention levels will thus depend on the circumstances. The quantities should be directly measurable…]. Constraints in the different exposure situations, including emergency situations, are in principle single values. However many of the existing emergency plans use a two-tier system of intervention levels, given per type of intervention. The upper level would then correspond to the constraint for that type of intervention and the lower level to the result of the optimisation process below the dose constraint, possibly to be further optimised during the emergency. Suggestion: - In (339) ‘constraints’ are used, allowing for different values for different intervention types, while in (348) the single ‘constraint’ is used suggesting a global value valid for an emergency situation independently of the intervention type. The working group takes the view that it is better to use throughout paragraph 348 the plural ‘constraints’. [62] It is certainly useful to have derived measurable quantities related to the avertable dose. However in the acute phase of an emergency, computed avertable doses will be used as input to the decision-making process, even if they cannot be directly measured. The working group suggests using the term ‘operational intervention levels’ for the results of the optimisation process in the case of an emergency situation. Suggestion: - The working group suggests to use in paragraph 348 the term ‘operational intervention levels’ for the results of the optimisation process; and not to require that these levels are always measurable. [63] Paragraph 349 states that [The benefit of a particular protective action within a programme of intervention should be judged on the basis of the dose averted …by that specific protective action. Thus each protective action has to be considered on its own merits.]. Although correct, a thoughtful optimisation scheme should also consider priorities and relationships between intervention types. E.g. a situation could arise that the less disrupting intervention would avert enough dose as not to justify the more disrupting evacuation any more. Suggestion: - Add in paragraph 349 the notion that a thoughtful optimisation scheme should also consider priorities and relationships between intervention types. 7 About the protection of the environment (chapter 10) [71] Environmental protection is much more than safeguard non-human species. It also includes sustainability, pollution control, general hygiene, land use, safeguard biotic compartments (atmosphere, deep sea, geological layers, South Pole, outer space...). In short, there is a need for an integrated environmental approach. The purpose of the new framework is a harmonised approach with other (non-radiological) pollutants. However, the proposed protection system (reference organisms) is similar to the existing ICRP-system for the protection of humans (reference person). The working group takes the view that the countless number of living species on earth cannot reasonably be reduced into a manageable number of reference organisms. Suggestion - Replace the reference animal and plant approach by an integrated environmental protection approach, based on a set of ambient specific activity levels. This implies the development of a framework to deal with the unavoidable very high contamination levels of small abiotic compartments (geological layers (waste disposal), remote areas (testing of nuclear weapons) and with large scale dilutions (atmosphere (Kr-85), deep sea (sea dumping)). The real challenge will be the development of an ecosystem approach for water, soil, atmosphere… and the acceptance of the integrated environmental protection approach by the general public. 8 About the implementations of the commission's recommendations (chapter 11) [81] A new separated chapter has been included, principally concerned with organisational features that may help in the implementation of the Commission’s recommendations. Some important features are quoted, like: • The importance of a regulatory authority clearly separated from organisations that conduct or promote activities causing radiation exposure; • The availability of the appropriate expertise in the different organisations involved in radiological protection and safety; • The definition of responsibilities of the different organisations and individuals, and the delegation of responsibility or authority; • The importance of safety culture and of experience feedback. All those features need a strong implication of organisations and individuals to become a reality and not only a vow or an ideal situation. It is important to actually accomplish what is said to be done. In particular safety culture and experience feedback asks for more implementation Suggestion: - Consider the necessity to give more importance on the actual implementation of the organisational features that may help in the implementation of the Commission’s recommendations, and on the implementation of means to verify their efficiency. Members of the BVS-ABR working Group Antoine Debauche, Institut National des Radioéléments (IRE) Henri Drymael, Association Vinçotte Nuclear (AVN) Gilbert Eggermont, Belgian Nuclear Research Centre (SCK•CEN) Jean-Louis Genicot, Belgian Nuclear Research Centre (SCK•CEN) Herwig Janssens, XIOS Hogeschool Limburg, VUB (XIOS-HL, VUB) Pierre Kockerols, Vice-chairman (BVS•ABR) Patrick Smeesters, Federal Agency for Nuclear Control (FANC•AFCN) Alain Sohier, Belgian Nuclear Research Centre (SCK•CEN) Michel Sonck, Association Vinçotte Nuclear (AVN) Filip Vanhavere, Belgian Nuclear Research Centre (SCK•CEN) Hans Vanmarcke, Belgian Nuclear Research Centre (SCK•CEN)