|PART 2 OF COMMENTS IN 6 PARTS
Comments on Draft for Consultation
2005 RECOMMENDATIONS OF THE INTERNATIONAL
COMMISSION ON RADIOLOGICAL PROTECTION
David C. Kocher
SENES Oak Ridge, Inc.
Center for Risk Analysis
Oak Ridge, Tennessee, U.S.A.
Introduction (Section 1)
Paragraphs (4) and (5). It might be helpful, either here or in a separate Annex, to summarize in more detail the evolution of the Commission’s basic recommendations, given that current standards in the U.S. (if not elsewhere) are still based on Publication 26. Topics to be summarized could include, for example, dose limits, dosimetric quantities used in dose limits, and the types of models used to calculated dose coefficients for intakes of radionuclides, as well as how the principles of justification, optimization, and dose limitation and their applications have changed over time.
Paragraph (8). Absent here is any mention of how potential exposures are treated in the draft 2005 Recommendations. Given that Publication 76 is listed in Table 1, should some mention of potential exposures be included in the bullet items in this paragraph?
Paragraph (8), third bullet item. Does this mean that the principle of optimization should be applied only to individual sources? If so, this statement implies that optimization of individual sources results in optimization of all sources of exposure combined. However, it’s not obvious to me that this is necessarily the case.
Paragraph (8), sixth bullet item. Surely it is a patient’s risk, not dose, which should be commensurate with the clinical benefit expected. I believe that the Commission’s unwillingness to embrace risk as fundamental to a system of radiological protection is a particularly important shortcoming in regard to recommendations on medical exposure.
Paragraph (10). While these statements are reasonable, I think that they are weakened somewhat by the Commission’s unwillingness to use risk to a greater extent in its system of radiological protection. That is, the draft 2005 Recommendations don’t give much information which can be used to properly evaluate risks from radiation exposure and compare then with risks from other similar hazards.
Aim and Scope of Commission’s Recommendations (Section 2)
Paragraph (14), last sentence. While I can agree with this statement, it is nonetheless the Commission’s responsibility to ensure that its recommendations conform to progressive ethical norms in such areas as full disclosure of risks due to radiation and informed consent.
Section 2.2. A change in the draft 2005 Recommendations compared with recommendations in Publication 60 is that the previous distinction between “practices” and “interventions” has largely been abandoned, and that situations previously viewed as interventions are now described as “existing controllable exposure situations.” I support this change. However, I believe that the change should be discussed in more detail, given that the previous approach was so important in Publication 60. This section is perhaps the place for such a discussion, e.g., in Paragraph (22). As noted in other comments, however, the change in terminology does not eliminate ambiguities in meanings of such terms as “normal situation” unless all terms used to describe different types of exposure situations are defined clearly.
Paragraph (18). I’m not convinced that it is a good idea to remove the principle of justification from the system of radiological protection. The arguments here do make sense if the term “practice” is interpreted on a large scale, e.g., if it refers to such things as use of nuclear power and use of radioactive materials in research and industry. However, it seems to me that the principle of justification is still a useful part of a system of radiological protection if it is viewed as also applying to more specific situations. For example, I believe that the principle of justification can be used to ban use of radioactive materials in children’s toys, costume jewelry, and in other frivolous ways, and I believe that the Commission should come out strongly against frivolous uses of radioactive materials even though they might provide a net positive benefit to society by increasing employment opportunities or income for sales organizations. I also think that there are situations within a fully justified practice where particular exposure situations should be avoided on grounds of inadequate justification.
I like the principle of justification, even if it has little impact on uses of radiation or radiological protection, because it represents a clear statement of a bedrock principle. Fundamental principles should not be abandoned unless there is clear benefit in doing so.
Paragraph (21), first sentence. Although discussions in Section 2.2 are general and introductory, I think that it is important even here to give a proper definition of “normal situation,” essentially because the term “everyday situations” used to define it here clearly describes many “existing controllable exposure situations,” as defined in paragraph (22). Does the description of a “practice” in paragraph (17) begin to describe a “normal situation”? The term “existing controllable exposure” also should be defined carefully.
It also seems to me that a determination that a particular source of exposure represents a “normal situation” or an “existing controllable situation” is not always clear-cut. How to classify exposures from mining and milling perhaps is an example. Releases beyond a site boundary during such operations presumably represent normal situations, but exposure due to buildup of contaminants in the environment beyond the site boundary over time during operations is not so easily classified. I think that the Commission should discuss examples of normal and existing controllable situations, especially in situations where the choice is not clear.
Paragraph (23), last sentence. I fully support this statement. Some recommendations on radiological protection by other organizations, such as the National Council on Radiation Protection and Measurements in the U.S., refer to “man-made sources” in describing the scope of recommendations. This gives the impression that only artificial sources are of concern, even though it is true that many sources of exposure to naturally occurring radionuclides result from actions by man and are, to some extent, controllable (and should be controlled).
Section 2.3. This section makes a distinction between “exclusion” and “exemption.” I wonder if the difference is all that clear from the explanations provided. Perhaps it would help to give specific examples of sources which might be excluded from the scope of the Commission’s recommendations and sources which would be within the scope but could be exempted. I think that this is particularly important in regard to artificial sources, because recommended exclusion levels for these are given in Table S2 (page 3) and Table 10 (page 53). I am concerned that the Commission may be making a distinction which seems artificial.
Indeed, the inclusion of man-made radionuclides in recommendations on exclusion may cause problems, in that it is incompatible with legislation in some countries. In the U.S., for example, the Nuclear Regulatory Commission is charged with regulating any radioactive materials arising from operations of the nuclear fuel cycle. Thus, by law, any artificial alpha or beta/gamma emitters produced in operations of nuclear reactors in any amounts are subject to regulation, which means that they can only be exempted but cannot be excluded. In general, I wonder if the concept of exclusion should be applied only to natural sources and artificial sources should be subject only to exemption (but not exclusion).
Paragraph (24), next-to-last sentence. Although I basically agree with this statement, as indicated in the previous comment, on what basis does the Commission claim that the concept of exclusion “will largely be of use in the control of natural sources”? Given that Table S2 (page 3) and Table 10 (page 53) include artificial (man-made) radionuclides in recommendations on exclusion, the Commission’s statement is not obviously true.
Paragraphs (25)-(28). I agree with these discussions. However, I also think that the Commission should recommend that general principles for exemption of sources, based on dose or risk, should be established; i.e., the preferred basis for exemption should be discussed here. For example, I believe that the recommendation on a minimum value of any dose constraint of 0.01 mSv per year provides a reasonable basis for exempting many artificial sources.
Paragraph (29), first two sentences. While I agree with this, I wonder if there are implications that should be explored. If waste disposal and remediation are parts of practices, are there important implications in regard to optimization; e.g., should the entire practice giving rise to waste disposal or environmental contamination be optimized or would the practice producing waste or contamination and the practice of waste disposal or remediation be optimized separately? It is conceivable that optimization of a practice which produces waste could result in waste forms which are not optimized with respect to the practice of waste disposal, and I can envision the same situation in regard to practices which produce environmental contamination and remediation of such contamination.
Paragraph (31), third through next-to-last sentence. I would comment that the way natural background is taken into account in radiological protection is different from the way background risks from exposure to naturally occurring hazardous chemicals are taken into account in regulating man-made substances. Risks due to the background of naturally occurring hazardous chemicals are basically ignored in regulating man-made substances, and this is an important reason why chemicals are regulated using a “bottom-up” approach, as discussed previously, in contrast to the Commission’s “top-down.”