2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by David C. Kocher, SENES Oak Ridge, Inc.
Commenting as an individual

PART 1 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. The Commission is to be commended for making its draft 2005 Recommendations available for comment. I also believe that the Commission is to be commended for efforts to be more candid in describing how its recommendations have evolved over time, in presenting the rationale for its recommendations, and in discussing difficulties in addressing certain issues. My comments are divided into general concerns about broad issues and specific comments on particular discussions in the draft document. I also have commented on some issues to support the Commission’s position, especially when it represents a new development. GENERAL CONCERNS Although there is much to like about the draft 2005 Recommendations, I believe that there are important shortcomings in several areas: • the Commission’s attitude toward, and treatment of, risk due to radiation in regard to its role in radiological protection; • a lack of attention to other approaches to health protection which have challenged the Commission’s approach, especially in regard to protection of the public from carcinogens in the environment, and a failure to properly take into account that radiological protection should be conducted in concert with other health protection programs; • a failure to acknowledge and take into account important issues of right-to-know and informed consent about exposures and risks due to radiation in some situations; • a failure of the recommendations on radiation weighting factors to account for an increased biological effectiveness of lower-energy photons and low-energy electrons, with the result that the Commission, in my view, has taken a position which cannot be defended on scientific grounds, is not adequately protective of human health, and leaves the Commission open to serious challenge on ethical grounds; • a failure to address potentially important issues of uncertainty. Some of these concerns are interrelated. My general concerns on these issues are summarized as follows. Many of my concerns are discussed in more detail in specific comments. View of Role of Risk in Radiological Protection It seems to me that the draft 2005 Recommendations reflect a basic attitude by the Commission that a system of radiological protection should treat risk as something to be avoided to the fullest extent possible; i.e., the role of risk in radiological protection should be minimized. In the past (i.e., in Publications 26 and 60), the Commission attempted to relate a dose-based system to a general notion of a limit on acceptable (barely tolerable) risk. However, the Commission now seems to prefer a purely dose-based system with no evident basis in the need to limit risk. This is a rather odd attitude when, first, the need for a system of radiological protection arises from a basic assumption that exposure to ionizing radiation at any level imposes some risk and, second, risk due to radiation is basically what people are concerned about. In my opinion, the Commission needs to embrace limitation of risk as the fundamental basis of a protection system, rather than appear to run away from it. Role of Radiological Protection in General Programs of Health Protection It seems to me that the draft 2005 Recommendations reflect another fundamental and pervasive attitude by the Commission that radiological protection can be (and should be) conducted in isolation, and that there is no need to take into account other health hazards of a similar kind and to address all similar hazards in harmonious ways. I have in mind approaches to health protection for hazardous chemicals, especially protection of the public from exposure to chemical carcinogens in the environment. As I see it, there are two general issues here. First, I believe that the Commission needs to recognize that its basic approach to health protection from exposure to ionizing radiation differs fundamentally from an approach which is widely used for other environmental carcinogens. In essence, the Commission’s system represents a “top-down” approach involving a limit on dose (risk) and a requirement to reduce doses (risks) below the limit using the principle of optimization. However, regulations for other environmental carcinogens in some countries, which often are applied to radionuclides as well, are based on a different (and opposite) approach (“bottom-up”) involving a goal for risk (often zero) and allowance for relaxation of risks above the goal on the basis of such considerations as cost and technical feasibility. Why is this difference important, and why does the Commission need to recognize it? For starters, the “top-down” approach used by the Commission represents a minority view; i.e., most similar hazards are regulated using the opposite “bottom-up” approach. More importantly, the Commission’s system of radiological protection has come under increasing attack on the grounds that it allows substantially higher cancer risks than allowable risks from exposure to other carcinogens. To cite an important example, the U.S. Environmental Protection Agency, which has responsibilities for setting standards to limit radiation exposure of the public under several environmental laws (e.g., the Superfund law that governs cleanup of contaminated sites), has gone on public record and has testified before the U.S. Congress that radiation protection standards of the U.S. Nuclear Regulatory Commission, which are consistent with the Commission’s recommendations on a public dose limit and appropriate dose constraints, are not adequately protective of public health. Although this dispute involves standards for cleanup of radioactively contaminated sites, accusations about the inadequacy of cleanup standards have affected other areas of radiological protection, such as efforts to develop guidance for all federal agencies on a dose limit for the public. Even though assertions about the inadequacy of radiation protection standards are ridiculous, because they ignore the primary importance of the ALARA principle in reducing doses far below applicable limits and constraints, such accusations are serious and they resonate with a public that desires lower risks and, therefore, believes that the other approach to health protection is better. I believe that the Commission somehow needs to address such concerns about its system of radiological protection head-on. The second issue is that there is a need to compare risks due to radiation with other imposed risks in making all kinds of decisions. Not only does this indicate the need for a proper emphasis on risk in radiological protection, but it indicates to me that the Commission should address (or at least be cognizant of) important issues of harmonization of regulations for different carcinogens, so that national authorities can make reasonable choices about different options which entail different risks. The two approaches to health protection can be harmonized, and I believe that the Commission needs to give guidance on how this can be done. It seems to me that the draft 2005 Recommendations reflect a kind of bunker mentality by not addressing how a system of radiological protection fits into a larger scheme of overall health protection. In this day and age, I don’t see how radiological protection can be conducted in isolation with what appears to be a “go away and leave us alone” attitude. Right-To-Know and Informed Consent A major development in the last two decades has been an increasing recognition of the basic right of people to be informed about involuntary risks which are imposed on them and, in some circumstances, to give their consent. I believe that the draft 2005 Recommendations do well in beginning to address the importance of stakeholder involvement in the process of optimization, at least in general terms, but I believe that the draft document has fallen far short of what is needed in addressing important issues of right-to-know and informed consent. I would note two examples here. The first concerns medical exposures. I did not find any discussion in the draft document about a patient’s right-to-know about risks from radiation procedures. For example, women who regularly undergo mammography examinations for breast cancer surely have the right to be informed about the risks of breast cancer associated with doses of low-energy x rays they receive, along with information about the benefits. Without full disclosure of risks and benefits, how can women make informed decisions about whether such procedures are right for them? A second example concerns people who work as receptionists (say) in a medical x ray facility and receive doses routinely while at their place of work. The Commission apparently does not consider such individuals to be radiation workers. However, these people surely have a right to information about their doses and risks, so that they can decide whether to accept them. There seems to be a fear in the radiological protection community that giving people information about their doses and risks is bad, because it might cause them to decide against use of technologies which benefit society or medical procedures which would benefit them directly. However, the implicit message is that people are not able to use information wisely. I submit that most people are smarter and more reasonable than they have been given credit for, and that censorship of information is basically wrong. I believe that the Commission needs to come out unequivocally on the side of full disclosure of information and informed consent. Recommendations on Radiation Weighting Factors for Photons and Electrons I do not see how the Commission can continue to recommend that the radiation weighting factor should be one for photons and electrons of all energies. The draft 2005 Recommendations do acknowledge evidence that orthovoltage (e.g., 180-250 kVp) x rays are biologically more effective than higher-energy gamma rays and that lower-energy x rays are more effective than orthovoltage x rays. In addition, although this is not discussed in the draft document, the Commission surely is aware of the extensive data on the increased biological effectiveness of low-energy electrons emitted in beta decay of tritium. However, the Commission has presented arguments, which are rather lame in my view, that such differences do not need to be taken into account in radiological protection. I will discuss my concerns in more detail in later comments, but I believe that there are two basic problems with the Commission’s position on this matter. First, although the Commission strives to base its recommendations on sound science, with due allowances made for the needs of a practical system of protection, in no way does the Commission’s position represent sound science. Furthermore, the Commission’s position is open to criticism on grounds that it is not adequately protective of human health. The second basic problem is the ethical stance that the Commission’s position represents. To give just one example, does the Commission think that it is proper that a woman’s physician, in considering risks and benefits of mammography x rays, should assume that the risk from exposure to low-energy x rays is the same as the risk from exposure to high-energy gamma rays? If the physician were to inform the patient about her risks and benefits, does the Commission believe that the same assumption is proper? The answer, apparently, is yes, but I submit that the Commission’s position is subject to serious challenge on ethical grounds. As discussed in later comments, there is no evident reason why a practical system of protection can’t take increased radiation weighting factors for low-energy low-LET radiations into account to an appropriate extent. Issues of Uncertainty The draft 2005 Recommendations are largely silent on issues of uncertainty, including uncertainties in risks from whole-body or partial-body irradiation, uncertainties in data on biological effectiveness that underlie recommendations on radiation weighting factors, and uncertainties in methods of estimating organ doses from intakes of radionuclides. There are brief qualitative discussions of some uncertainties in Annex A, and some uncertainties are discussed in more detail in other Commission reports. However, I think that it is important to reveal the state of knowledge of scientific information underlying the Commission’s recommendations. Quantitative information on uncertainties at least should be summarized in this document. In my view, one reason that disclosure of uncertainty is important is that, as in the basic approaches to health protection discussed above, the Commission’s position on how uncertainty should be taken into account in radiological protection and risk assessment is in the minority. At least in the U.S., health protection standards for environmental carcinogens are applied and health risks are assessed on the basis of upper credibility limits, taking into account uncertainties in exposure and risks associated with given exposures. Such an approach requires disclosure of uncertainties. If uncertainties in radiation exposures, doses, and risks are not disclosed, approaches to risk management and assessment for different types of hazardous substances are not harmonized, and this can lead to problems for decision makers. I am not necessarily advocating that radiological protection should be based on upper credibility limits of exposures, doses, and risks, although I think that this approach should be given serious consideration. However, by not disclosing uncertainties, the Commission is again vulnerable to challenge on grounds that other approaches to regulation and risk assessment are more protective of human health. The Commission at least needs to discuss whether or not it attempts to provide central estimates of dose and risk (detriment), and it needs to fully justify the use of central estimates if that is the case, given the evident importance of uncertainty. Overall View of Recommendations As I consider the draft 2005 Recommendations as a whole, it seems to me that they reflect a certain nostalgia, i.e., a desire to go back to the period up to mid-1970s when the Commission’s recommendations were largely unchallenged and little attention had to be paid to outside influences. However, I submit that we can’t go back in time, and that the Commission needs to develop recommendations that conform to ways in which progressive societies and governments are addressing issues of health protection at the beginning of the 21st century. The draft 2005 Recommendations include what can be interpreted as a plea for relevance; e.g., see paragraph (S20). If the Commission wishes to be viewed as relevant, I believe that the Commission needs to be more cognizant of challenges and criticisms which have been directed against it and to be proactive in addressing them. The draft document does not strike me as being particularly responsive to some of those challenges and criticisms. For example, in many respects, the state-of-the-art in radiation risk assessment is leaving important aspects of the Commission’s approaches to radiological protection far behind. The danger is that the outside world may come to view the Commission as increasingly less relevant in addressing its concerns, and the Commission’s influence may become more restricted and less important. SPECIFIC COMMENTS Summary of the Recommendations Except for the mention of a “balancing of risks and benefits” in the quote from the 1990 Recommendations in paragraph (S20), strikingly absent from the Summary is any mention of risk and its role in the Commission’s system of radiological protection. Indeed, I suspect that it speaks volumes about the Commission’s attitude on the use of risk that the Summary does not even give the recommendations on nominal probability coefficients for stochastic effects. Another general comment is that there is no mention in the Summary of the Commission’s recommendations on medical or potential exposures. What seems particularly important is to at least mention whether or not the maximum dose constraints in Table S1 apply to those two situations. Without such an explanation, Table S1 could be misinterpreted, given that medical and potential exposures certainty are “exposure situations that can be controlled.” I also believe that a brief discussion of the basis for the maximum dose constraints in Table S1 needs to be given in the Summary. Clear definitions of “normal situations” and “controllable existing exposures” also are needed here. Without explaining these terms, the Commission’s intentions about specific situations to which different maximum dose constraints should be applied are vague. Neither of these issues appears to be addressed in the main report. Paragraph (S5) or (S8). The term “class of exposure” is used in the Summary without explanation. I think that the meaning of this term and an identification of the different classes should be given in the Summary. Footnote to Table S2. Here and in Table 10 on page 53, the term “daughters” should be changed to something like “its decay products” (the term “daughters” is no longer used in health physics and is seen as mildly offensive in some quarters). Paragraph (S13). I believe that this paragraph should begin with a brief statement about what “effective dose” is and how it is used in the system of radiological protection. Paragraph (S15), last sentence. This statement seems quite profound. However, I am at a loss to understand what it means, and I didn’t find any similar statement or explanation of it in the main report. What do the words after the comma mean in actual practice?