2005 ICRP Recommendation

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

NEA Comments on Specific Paragraphs (Submission 5 of 5) (215) The physicians (insert: and other professionals) (Comment: To assure that all relevant workers are trained) involved in the processes that irradiate patients should always be trained in the principles of radiological protection. This is because the exposures of patients are deliberate. Except in radiotherapy, it is not the aim to deliver a dose of radiation, but rather to use the radiation to provide diagnostic information or to conduct interventional radiology. That exposure is not limited by any regulatory process, but is controlled by the physician, who therefore should be aware of the risks and benefits of the procedures involved. The need for training is accentuated by several recent cases of radiation injury to patients, the root cause of which appears to be insufficient training. 9.1.1 The generic justification of a defined radiological procedure (218) The generic justification of the radiological procedure is a matter for national professional bodies, (insert: and as relevant) (Comment The EGIR feels that it should be more clearly stated that consultation with authorities is related to the relevance of the situation, rather than the vague “sometimes” of the original phrase) (Deleted: sometimes) in conjunction with (regulatory authorities) (insert: national health authorities.) (Comment: Here, health authorities, rather than regulatory agencies, should be noted.) The total benefits from a medical procedure include not only the direct health benefits to the patient, but also the benefits to the patient's family and to society. Although the main exposures in medicine are to patients, the exposures to staff and to members of the public who are not connected with the procedures should be considered. The possibility of accidental or unintended exposures (potential exposure) should also be considered. The decisions should be reviewed from time to time, as more information becomes available about the risks and effectiveness of the existing procedure and about new procedures. 9.3 The optimisation of protection for patient doses (222) The medical procedures causing patient exposures are clearly justified and are usually for the direct benefit of the exposed individual and consequently somewhat less attention has been given to optimisation of protection in medical exposures than in other applications of radiation sources. (insert: However, while optimisation of protection for patient exposures is somewhat conceptually different that for worker or public exposures (for example) the optimisation of protection in patient exposures does not necessarily mean the reduction of doses to the patient) (insert: it is still an essential aspect of applying the Commission’s system of protection to patients.) (Comment: The EGIR feels that optimisation of patient protection is as important as justification, and should be clearly presented as such.) It is difficult to make a quantitative balance between loss of diagnostic information and reduction in dose to the patient. The use of diagnostic reference levels is seen by the Commission as an important and useful reminder to check that doses are not excessive. 9.4 Helpers and carers, and the public (225) The exposure, other than occupational, of informed and consenting individuals helping to support and comfort patients, is a part of medical exposure. This definition includes the exposures of families and friends of patients discharged from hospital after diagnostic or therapeutic nuclear medicine procedures. Their exposure is different from that for public exposure, since the constraints on their exposures are not restricted by the dose limits. In Publication 73 the Commission specified that dose in the region of a few millisieverts per episode is likely to be reasonable (Comment: The dose level of 20 mSv, given in Tables S1 and 7, seems to be too high if applied to children or pregnant women, and to be in contradiction with this paragraph. A Coherent approach, between this section and the recommended dose constraints, should be developed.). This constraint is not to be used rigidly. For example, higher doses may well be appropriate for the parents of very sick children, if they are properly informed of the risks. (226) Also, medical exposures are incurred by those volunteering for research involving exposures to radiation. (Comment: It was noted that there is some question of whether exposures required by insurance companies – or in other “medico-legal” contexts, are in fact “Medical Exposures” at all. An extensive conference in Dublin addressed this issue, which is primarily one of justification (and then of course optimisation.). In any case, the EGIR felt that this reference to exposures required by insurance companies was not appropriate here and should be deleted. For example, this is not the case in Italy, insurance companies can not require this.) (Deleted: and insurance companies may require individuals to receive medical exposures) In these cases again, the public constraints are not appropriate and national authorities should use higher values similar to those quoted in the paragraph above. (Comment: Other rationale for exposures, for security or safety issues are not sufficiently addressed in this section. Also, for all the cases mentioned in this paragraph, justification is a clear issue on which to expand) (227) Some public exposure may result from wastes discharged by nuclear medicine departments. The implications of such discharges to sewers and of airborne effluents should be assessed to ensure the relevant national constraints for public exposure are met. The adventitious exposure of members of the public in waiting rooms and on public transport is not high enough to require special restrictions on nuclear medicine patients (Comment: The EGIR feels that the deleted phrase is too specific, and that such treatments may change in the future) (Deleted: except for those being treated with radioiodine for thyroid cancer (Publication 73 and 94, ICRP, 1996a, 2004) . 10. POTENTIAL EXPOSURES (Comment: The risk approach that is used in this section is very much appreciated.) (Comment: A table, as was used for dose constraints, would be useful in this section to describe risk constraints.) (228) Potential exposures are those that may or may not occur (Comment It would be useful to more clearly define Potential exposures. For example, are transport exposures, which are not certain, Potential? This could be a term added to the Glossary that was proposed by the EGIR.) . Such events can be foreseen and their probability of occurrence estimated, but they cannot be predicted in detail. It is necessary to control both the probability and the severity of exposures. There is usually an interaction between potential and normal exposures (see Publication 64; ICRP, 1993a). For example, actions taken to reduce the probability of a potential exposure may increase the normal exposures. On the other side, storage of waste rather than its dispersal will reduce normal exposures, but will increase the potential exposures. (234) In Publication 76, the Commission recommended such a generic risk constraint for occupational potential exposures of 2 10-4, based on the observation that where the Commission’s system of radiological protection (including optimisation) had been applied, annual occupational doses to an average individual were rarely greater than about 5 mSv, and the ICRP cancer death risk for occupational exposure in Publication 60, 4 10-2 Sv-1. The reasoning also assumed a scenario unlikely to affect more than a limited number of individuals at the same time (see also paragraph 237). For potential exposures of the public, Publication 76 recommended a corresponding risk constraint of 5 10-6, based on an assumed average dose to individual members of the public from normal authorised discharges of 0.1 mSv or less, and again limited to potential exposure scenarios that could only be expected to affect a limited number of individuals. (Comment: This paragraph seems to suggest fixing constraints on the basis of protection “achieved”. This approach is completely different than that suggested for dose constraints. The EGIR suggests that the Commission rethink this, and that the basis for risk constraints should be much more clearly expressed.) (239) Sometimes, after the termination of practices and in the aftermath of events involving radioactive contamination, radioactive residues may remain in the environment and fragments may become very sparsely distributed in the environment, usually as ‘hot particles’. For these situations, the Commission continues to recommend the derivation of protection criteria based on the principles described in this section.(Comment: The Commission’s recommendations for protection against hot particles are not clear from this paragraph. It is suggested to rewrite the last sentence as proposed.) (insert: Specifically,) (deleted: namely of) the unconditional probability that members of the public would develop fatal stochastic health effects attributable to the exposure situation (insert: could be the criteria used as the benchmark against which to gage the optimisation of protective actions. ) (240) In these situations, such a probability should be assessed by combining the following probabilities: the probability of being exposed to the hot-particle residues; the probability of incorporating a hot particle into the body as a result of such exposure; the incurred average radiation weighted dose as a result of such incorporation; and, the probability of developing a fatal stochastic effect from that dose. These probabilities should be integrated over all the range of situations and possible doses. In establishing such criteria, consideration should be given to the possibility that localised tissue reactions may also occur as a result of the incorporation of hot particles. (Comment How you would act to reduce potential exposures would be difficult and is not explained in these paragraphs. ) 11. THE PROTECTION OF THE ENVIRONMENT (Comment: This section is written more as a discussion of what the Commission intends to pursue, rather than a presentation of the Commission’s recommendations. Because the Commission is waiting, correctly, the advice of Committee 5, this sections should present recommendations of what to do in the mean time. For example, mention the science that we currently understand (FASSETT, ERICA, etc.), and suggest a precautionary approach. While protection of ecosystems is most likely a goal, this is currently too little understood, so the Commission suggests the protection of the individual, through a reference individual approach, until more is known about the link between individuals of particular species and overall ecosystem protection.) (Comment: The introduction to Publication 91 is good and should be used here) (241) (Comment: This chapter could be considerably reduced if it were to focus uniquely on policy, as for example in paragraphs 246 and 247) (Comment: The EGIR feels that Appendix B is far too detailed and of little use. It is thus suggested that Appendix B be deleted.) (Comment: This chapter seems to be a “plan for future work”, but not a recommendation. This should be clarified, as there is not necessarily an agreement on the proposed plan.) The Commission has not made any specific recommendations with regard to protection of species other than the human, but in its 1990 Recommendations in Publication 60 it did express the view that ‘The Commission believes that the standards of environmental control needed to protect man to the degree currently thought desirable will ensure that other species are not put at risk. Occasionally, individual members of non-human species might be harmed, but not to the extent of endangering whole species or creating imbalance between species. At the present time, the Commission concerns itself with mankind’s environment only with regard to the transfer of radionuclides through the environment, since this directly affects the radiological protection of man.’ (242) The Commission still believes that this judgement is correct in general terms. Thus it is probably true that the human habitat has been afforded a fairly high level of protection through the application of the current system of protection. However, there are now also other demands upon regulators, in particular the need to comply with the requirements of legislation directly aimed at the protection of wildlife and natural habitats; the need to make environmental impact assessments with respect to the environment generally; and the need to harmonise approaches to industrial regulation, bearing in mind that releases of chemicals from other industries are often based upon their potential impact upon both humans and wildlife. All of these demands are currently being met in a multitude of differing ways, partly because of the lack of advice on the subject at international level, and partly because there are therefore no agreed assessment procedures, criteria, guidelines or data sets with which to approach these issues in a coherent way. This, in turn, leads to different national approaches being developed and makes international harmonisation difficult. (Comment: The suggestion that there is a need for broad international standards in this area is premature.) (249) In order to be of practical value, and to assist in their interpretation, the Commission believes that bands of derived consideration levels for Reference Animals and Plants could be set out in logarithmic bands of dose rates relative to normal natural background dose rates of the reference organisms. Additions of dose rate that are below their background might then be considered to be of low concern, and those that are orders of magnitude greater (Comment: This is the correct view, not that presented in the figure of appendix B ) than background would be of increasingly serious concern because of their known adverse effects on individual organisms. But the need for any managerial action, however, would be dependent upon, for example, factors including the numbers and types of individuals affected, the nature of the effects, the spatial and temporal aspects of contamination, and legal requirements.