2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by Allen Brodsky, Sc.D., CHP, CIH, DABR, Adjunct Prof. of Radiation Science, Georgetown Univ.
Commenting as an individual

Allen Brodsky, Sc.D., CHP, CIH, DABR 121 Windjammer Road Berlin (Ocean Pines), MD 21811 (410) 641-6523 FAX: (410) 208-1015 E-mail: ALBRODSKY@AOL.COM Date: December 6, 2004 To: Members, International Commission on Radiological Protection From: Allen Brodsky, Sc.D., Founding Member, Health Physics Society Through: Dr. Kenneth R. Kase, Past President, Health Physics Society Subject: My personal comments on the proposed revision of ICRP general recommendations These comments have been more immediately inspired by the article by Ralph L. Andersen in the December 2004 Health Physics News, and represent my opinions and perspectives alone and not necessarily those of any associates or affiliations. Until the article by Ralph Andersen, I was not sure I would take the time to offer comments. As indicated in the background remarks below, I did not feel I could take the time to adequately examine and comment on each detailed change in the proposed 2005 ICRP recommendations. However, I have now examined much of the proposed recommendations and have some general conclusions. After stating my general conclusions, I will provide some background remarks and some suggestions to consider in formulating basic radiation safety recommendations. General Conclusions: The proposed ICRP revisions should not be published as recommendations superseding the previous recommendations in ICRP 60. If ICRP decides to publish these recommendations, after consideration of, and attempts to incorporate, all comments, they should be labeled as “commentary” or “additional guidance.” Also, future publications should incorporate on the front cover disclaimers such as: “NOTHING IN THIS DOCUMENT SHOULD BE INTERPRETED TO REQUIRE CHANGES IN ANY NATIONAL LAWS OR REGULATIONS ON RADIATION SAFETY. PROVISIONS OF PREVIOUS ICRP RECOMMENDATIONS AND REPORTS HAVE BEEN FOUND TO PROVIDE ADEQUATE SAFETY WHEN IMPLEMENTED BY NATIONAL BODIES.” Since the previous ICRP general recommendations there has not been, nor is there likely to be in the near future, significant changes in risk estimates or failures in implementation of previous recommendations to justify renewed regulatory changes. Such changes would waste resources that could be put to better public health use, and would add further regulatory burdens to beneficial uses of radioactive materials. This is implied within the proposed ICRP document, but it is too subtle if buried within the text. Unfortunately, regulators (in some nations) who might not be familiar with the safety records of the beneficial applications of nuclear energy and byproduct radionuclides, will still take seriously the need to again convert into national regulations any ICRP general recommendation revisions. Because my conclusions above are negative, I need to follow them with some background, positive commentary, and specific suggestions. Commentary: I am very appreciative of the past efforts of the ICRP to provide recommendations and guidance on radiation protection, and have made good use of ICRP documents, and concomitant ICRP and NCRP recommendations, in many aspects of my 55-year career in radiation protection. I also commend the ICRP on the new procedure of widely publishing draft documents for comment, and have been in favor of this procedure since my early efforts in writing standards and regulations in the 1950s. One never can predict from what practicing person might come an important idea or perspective. My perspectives originate from a long background of interest and participation in the use and writing of standards, recommendations, and regulations since the 1950s. ICRP recommendations have been appreciated and considered in all of these endeavors, even if not adopted verbatim. I was involved in 1957-58 in converting ICRP/NCRP recommendations into the early Manual Chapters used by the U.S. Atomic Energy Commission, under Dr. G. Victor Beard and Dr. Charles L. Dunham. In 1958-61, I was assigned, under the direction of Les Rogers, my Branch Chief, and Bob Lowenstein, Director of the Division of Licensing and Regulation, USAEC, to review the 180 letters of comment on the 1961 revision of Title 10 Code of Federal Regulations, “Standards for Protection Against Radiation” (10 CFR 20), and to prepare drafts for further review and comment. I was required to discuss in writing the details of my acceptance or rejection of each comment in each of the 180 letters. This effort on my part ranged only over about 2.5 years (while performing many other facility and practice safety proposals and exempt item evaluations), even though I remember discarding about 17 drafts in the process of obtaining concurrences from many other scientists, engineers, and lawyers within the USAEC, and reworking many revisions with Les and Bob. After returning to government in a later position under Robert E. Alexander, I was assigned in early 1986 to continue the years of work of several other full-time health physicists in reviewing over 800 letters of comment to convert the ICRP 26 and 30 recommendations into revised 10 CFR 20 regulations that were later adopted in the 1990s. Bob had commended me for my detailed write-ups the previous ten years of how each comment was considered in respect to others on the number of “Regulatory Guides” that I prepared to provide licensees with acceptable guidance on implementing the 10 CFR 20 regulations. Some notable health physicists even questioned whether such a revision of regulations in response to changes from ICRP II was necessary back then to improve public and worker health. After several months, I decided to accept an offer for early retirement in 1986; I had been through this before and was not sure even then that replacement of the earlier regulation was necessary for health protection. In 1959-61, as Chair of the Standards Committee of the Health Physics Society under Elda E. Anderson and John Laughlin, I proposed that the HPS not just comment on, but be an originator of, American National Standards in the field of radiation protection. In a later 1967-70 term as Chair under Walter Snyder, Wright Langham, and Newell Stannard, I was finally able to persuade the HPS Board of Directors to join with the American National Standards Institute in writing standards, and I set up the first three Committee 13 Standards Working Groups on uranium bioassay, film badge dosimetry, and safety requirements for handling radioactive materials, chairing the latter two. As a result of my naïve desire to satisfy all commenters in writing consensus documents, I failed to complete the latter two before resigning to change into a busy career as radiation therapy physicist and research professor. Later, in the 1975-95 period, I joined the working level of many ANSI working groups and chaired the uranium bioassay working group that finally issued a standard after 25 years. I know of the amount of work required to examine and re-write standards to resolve mountains of comment. Indeed, a serious effort is required to consider all comments in respect to document details and the comments of others whenever a public health document is under revision. Thus, you can see that I do not take lightly ICRPs efforts, but am also concerned about the amount of work and diligence necessary to convert ICRP recommendations to regulatory language and provisions that can be audited and inspected for enforcement purposes. I also know how a completely new revision of basic ICRP recommendations might well cause a cascade, or avalanche, of work by regulators – many of whom think that every new “recommendation” of ICRP must be converted appropriately to changes in regulations or standards, and who will seek to employ new staff for the conversion. (I note that my fit to Parker’s data but including the year 1928 when the ICRP was formed as a point of 1 standard, shows a perfect exponential increase in standards to be read by health physicists (N = exp(0.1085[T – 1928]), which passes through Parker’s data (collected by Jack Selby) at about 105 documents in the year 1970 (Brodsky 1978). If this fit is still true, there must already be over 2,500 documents that the health physicist writing new guidance must now read. Perhaps Jack, or someone on ICRP, would like to count them again.) Suggestions: 1. Tissue weighting factors. My impression is that there is no scientific justification for changing tissue weighting factors again. Although I have not reviewed the very latest literature on the subject, I delved carefully into the subject in writing my book reviewing radiation risks (Brodsky 1996), and examined reviews and data from the Japanese studies for several years after. I do not believe that there could so far be statistically significant changes in organ-specific risk factors even at the highest doses received in Hiroshima and Nagasaki to justify disruption in current methods of estimating internal dose. It was interesting to note that the changes in tissue weighting factors that were substantial in detail between ICRP II and ICRP 26 and 30 did not change resulting overall risks of cancer mortality from exposure to clouds of mixed fission products from various reactor operating and cooling times (Brodsky et al 2001). Moreover, some observations of my own in my chapter examining evidence for hormesis, as well as recognition of the existence of adaptive responses to more severe stresses that are provided by small radiation doses, would indicate more time is needed to allow current research to provide a more definitive picture of radiation carcinogenesis and associated repair or hormetic processes at low radiation exposure levels. I suggest that the ICRP should let stand in place for the time being the excellent work of Warren Sinclair and colleagues in adjusting the higher-dose Japanese data to obtain appropriate measures of detriment in the ICRP 60 recommendations. These standards are quite conservative enough in the safety direction. 2. Justification, Optimization, and Limitation. Again, I suggest that the use of these criteria, already embodied in so many radiation safety regulations and programs, not be changed again just based on the different approaches of new ICRP committee members. Preceding the original definition of these criteria by ICRP, a similar set of criteria were embodied in Brodsky (1965), in which after reviewing the public health literature I could find no quantitative criteria or units for expressing human benefit. After some thought, I realized that to truly balance benefit vs. risk (as we called it in those days), a societal decision (by an appropriately organized body) was needed to quantize defined applications of radiation (and in further dimensions other produced agents of exposure) into allowed total public exposures according to constraints that differed by one order of magnitude each (the justification; items of no benefit would be given a zero total group exposure limit, under the assumed absence of hormetic effects). (This discovery might crudely be compared to the discovered need to quantize energy levels in atoms to further advance physical science.) Then, each successive nth item within a benefit group that would come up for approval (allowing an unlimited number of beneficial products to be proposed as exempt from licensing), would be assigned a sequential limit of total population exposure based on the nth term of a most slowly converging arithmetic series (a constraint). The actual exposure allowance for this nth item (in a jth group) would then be based on maximizing the benefit/risk ratio within the sequential dose constraint, placing the remainder allowed for that nth item into a bank for possible future items of advanced benefit (this was the optimization). Thus, justification, optimization, and limitation are all included in the organized decision and accounting scheme proposed in Brodsky (1965). Some later papers were presented after that publication, but I doubt that members of the ICRP have had the opportunity to review that scheme. The members of the ICRP will probably need to read my paper in detail to fully understand my concerns; however, I have tried to summarize my concepts as best I can in a few paragraphs. (It might be noted that, to illustrate my scheme, I selected in this 1960s paper a limit of 10 millirem per year to a member of the public as the dose limit from all present and future items released under exemptions for individual use. This was a dose limit that I deemed appropriate for my own family, and one that I had found allowed many beneficial applications of radioactive materials in consumer products. It is, of course, based on linear extrapolation of risks from higher dose levels, and thus might need to be revised in the future if well-defined hormetic effects should ever suggest.) As indicated in the chapter in Brodsky (1996) that critiques other publications on optimization by the ICRP (and discovers certain problems), a scheme such as that proposed in Brodsky (1965) is necessary if indeed an overall constraint on total annual dose to a member of the public is to be implemented and monitored, without at the same time using up an allowed dose constraint or limit and possibly preventing future application of some newly discovered product or service of enormous health benefit. The scheme could also be expanded into other dimensions to organize decisions on all possible human products. In fact, without considering other possible health uses of monetary or other resources, one can not truly attain a proper benefit/risk ratio if examining radiation detriments alone vs. beneficial applications. As Burton Weisbrod concluded in a book on the economics of public health (referenced in Brodsky (1965)), and which he expanded upon in later books, any society – no matter how wealthy – can assign only a certain amount of financial resources to public health. There are two choices: the money is used wisely and improves health; or it is used unwisely and depreciates the public health. These are, as ICRP recognizes, matters that must be considered with extreme care. I do not think that the current changes in justification, optimization, and limitation philosophy are warranted. Our profession should be considered just another specialty of the profession of public health. We need to be involved in the justification stage, even though as indicated in my paper other representatives of the public should also be involved; we have the knowledge and interest to be so involved, and the justification step should not be separated from the others. We should be interested in avoiding all unjustified expenditures of professional and government resources, and unnecessary burdens on economic progress (which is known to be well correlated with public health). 3. Converting ICRP recommendations to practice guidance. I have been particularly grateful for the work of the ICRP (particularly Karl Morgan, Walter Snyder, Keith Eckerman, and other ICRP colleagues, including those from other nations) in deriving for the many radionuclides and forms the estimated limits of intake and internal exposure, using the basic literature on animal experiments and human epidemiology. As part of my early work evaluating different uses and facilities at the USAEC, I became concerned about proper requirements for safety that at the same time would not be unnecessarily burdensome to the independent entrepreneur who develops beneficial applications. I was, through experience with accident cases and releases from processes, able to use the ICRP work to devise a scheme for judging when many of the facility, equipment and procedural requirements under review should be required based on quantity of radionuclide in use and the maximum relative internal dose per unit intake (which I misnamed “radiotoxicity” for want of a better word) (Brodsky 1980). When this scheme was used or compared with practices in the United States, it was found to prevent unacceptable exposures, and radiation accidents were found to be associated with quantities of specific nuclides in process for which the suggested safety features were not in place. The publication in 1980 was based on an earlier publication in 1965. A number of States in America adopted this scheme as a standard for reviewing license applications. After several other publications of this scheme, a more recent exposition was published to confirm that the original scheme need not be changed significantly as a result of the ICRP 30 values (Brodsky 1992). ICRP 60 would also not seem to require further appreciable changes in the scheme, which divides nuclides into particular categories extending over 8 orders of magnitude of “radiotoxicity.” It is important to note that in this scheme, criteria are kept simple in terms of quantity and types of radioactivity in process, without adjusting “radiotoxicity” according to the specific activity of the pure nuclide, except for uranium and thorium. The mass quantities, or specific activities of the pure nuclides for other nuclides in use, are not deemed limiting or a factor, because in undefined or changeable chemical processes it is the material with which the radionuclide is mixed that determines mass quantities released to the biosphere, thus limiting aerosol concentrations. I have been glad to see that ICRP and IAEA standards have generally adopted a wider range of relative radiotoxicity for the nuclides, to more aptly represent doses per unit intake. All of these schemes, and much additional regulatory and national standard guidance, would not have been derivable without the work of the ICRP. Adjustment factors for material in storage or in non-dispersible forms have also been adapted from the work of these international bodies. Thus, it is important for any new recommendations or guides to be consistent with whatever regulatory or practice guides or standards have already been developed and used effectively in the various nations. Spurious changes in what I have called “relative radiotoxicity” should not be made without checking on the agreement of results of application with “real-world” experience in health physics practice. Thus, my interest here is as a user of ICRP documents who wants to avoid unnecessary regulatory burden and maintain consistency and minimum cost in safety programs that have already been established. References: Brodsky A. Balancing benefit vs. risk in the control of consumer items containing radioactive material. Am. J. Public Health 55:1971-1992; 1965. Brodsky A. Rate of growth of standards and literature in radiation protection. In: Brodsky A., editor. Handbook of radiation measurement and protection, Vol. 1, Science and Engineering Data. Boca Raton, FL: CRC Press, Inc.; 1978, pp. 9-12. Brodsky A. Determining industrial hygiene requirements for installations using radioactive material. Reprinted as an historical paper in the 25th anniversary issue, Health Phys 38:1155-1171; 1980. Brodsky A. Properly relating radiation protection requirements to relative radiotoxicity and risk. In Miller K, editor. Handbook of Management of Radiation Protection Programs, 2nd edition. Boca Raton, Florida: CRC Press, Inc. 1992. Brodsky A. Review of radiation risks and uranium toxicity, with applications to decisions associated with decommissioning clean-up criteria. Hebron, Connecticut: RSA Publications; 1996. Brodsky A, Raine DA III, Moshaashaee. Estimating “acceptable emergency doses” from submersion in fission product clouds. Rad. Protection Management 18:17-33; 2001.