|The Interagency Steering Committee on Radiation Standards (ISCORS) is comprised of Federal Agencies in the United States that facilitate consensus on acceptable levels of radiation risk to the public and workers and promote consistent risk approaches in setting and implementing standards for protection from ionizing radiation. A goal of ISCORS is to improve consistency in Federal radiation protection programs. Specific objectives include: facilitating consensus on acceptable levels of radiation risk; promoting consistent risk-assessment and risk-management approaches in setting and implementing standards for protection from ionizing radiation; promoting completeness and coherence of Federal standards for radiation protection; and identifying interagency issues and coordinating their resolution. ISCORS is also a forum for Federal agencies to keep abreast of national and international radiation protection activities.
The ISCORS Federal Guidance Subcommittee appreciates the continued opportunity to offer our views on the draft recommendations of the International Commission on Radiological Protection (ICRP), and we commend the openness and responsiveness of the ICRP in making drafts available for public comment. The most recent draft, posted on the Internet for public comment on June 7, 2006, represents a considerable evolution from the earlier draft on which the Subcommittee previously commented. We believe that the latest draft ICRP recommendations are an improvement compared to the 2004 iteration. It is apparent that the ICRP addressed many, albeit not all, of the comments provided previously. We look forward to interacting with the ICRP as these recommendations continue to evolve.
The following observations present views developed by the Federal agency staff participating in the Federal Guidance Subcommittee of ISCORS. They are not intended to represent the official views of the Agencies. Federal Agencies will also be submitting general and specific comments reflecting their unique roles and responsibilities within the United States.
In the draft document posted for public comment on June 7, 2006, ICRP stated the following primary objectives:
• Take account of the new biological and physical information and trends in setting radiation protection standards.
• Improve and streamline the presentation of the recommendations.
• Maintain as much stability in the recommendations as is consistent with the new scientific information.
The ISCORS Federal Guidance Subcommittee offers the following comments on the draft document, and how these objectives have been achieved.
1. The ICRP has stated that these recommendations are intended to consolidate, simplify, and elaborate on the previous set of recommendations published in 1991 as ICRP Publication 60. However, the current draft does not appear to appreciably consolidate, simplify, or clarify the recommendations. For example, the draft simply indicates that many of the previously published values should be considered as constraints. Furthermore, much of the material that elaborates and expands on previous recommendations, in fact, describes the current state of the system of radiological protection being implemented by many well-run radiation protection programs throughout the world. With the conclusion that there has not been any significant change in radiation risks, there is no compelling public health and safety argument to make any significant changes to the current recommendations, or to national regulations that implement these recommendations.
2. The ICRP proposes changing the radiation weighting factors, tissue weighting factors, and nominal risk coefficients for cancer and hereditary disease. Of all of the material in the draft recommendations, these changes have the greatest potential for an impact on regulations promulgated by national authorities. Yet, some of these changes may be premature. The cancer incidence data used by the Biology Working Group is largely based on data published in the early 1990s (Thompson et al., 1994; Preston et al., 1994) using Japanese A-bomb data and the DS86 dosimetry. A new dosimetry system has since been developed, but the “new analyses of the latest A-bomb cancer incidence data are expected soon (Preston et al., in preparation)” [see Annex A, lines 1647–1648]. We believe that recommendations of the ICRP should be based upon published, peer-reviewed scientific information that reflects the current state of knowledge. Thus, we propose that the ICRP not adopt a new set of tissue weighting factors and nominal risk coefficients until the assessment of the A-bomb data is completed and published in a peer-reviewed journal for public scrutiny
3. The ICRP’s attempt to clarify the meaning and use of dose constraint is an improvement over the previous draft, but further clarification is needed. The use of the phrase “provides a fundamental level of protection” clouds the relationship of constraints and dose limits. We believe a constraint is a value that helps to ensure the achievement of a fundamental level of protection in the process of optimization. However, from an individual’s standpoint, it is the dose limit that provides the ultimate fundamental level of protection. The constraint, properly implemented in the context of a radiation protection program and optimization of activities, will contribute to ensuring that each individual is adequately protected. This is, in fact, how a well-run radiation protection program functions. Therefore, the dose constraint can be seen as a value, selected by the user, for use in the radiation protection program that the user employs to ensure compliance with the regulatory requirements, i.e., an administrative limit. The national authorities’ role is to ensure that each user establish appropriate values. Thus, we request that the ICRP further clarify how constraints and limits function within a radiation protection program and how the optimization of protection from one or more sources ensures that adequate protection for an individual is achieved.
4. As the draft recommendations have been developed, the ICRP continues to draw a connection between optimization of protection and the concept of a safety culture. This draft publication has not resolved the previous confusion between these two concepts. Optimization of radiation protection activities alone will not create a safety culture. Safety culture is a much broader and encompassing concept. Although an effective safety culture will contribute to continuing efforts to optimize protection, they are not equivalent. We believe that the underlying tenets of a safety culture and, in particular, the mindset of continually challenging the radiation protection activities to ensure that safety is being achieved, are also key components in the ongoing process of optimization. However, the relationship between optimization of protection and the concept of safety culture should be more clearly articulated.
5. An apparent increased radiation sensitivity observed in females has been described in publications of the U.S. National Academy of Sciences in 1990 (BEIR V) and 2005 (BEIR VII) and by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 2000). However, the ICRP does not recommend gender-specific data for the purposes of radiological protection, and continues to present gender-averaged tissue weighting factors and numerical risk estimates. Although we agree that the proposed approach provides adequate protection, we request that the ICRP clearly explain its rationale for this decision and how it accounts for gender differences in radiation sensitivity. Regulatory agencies may need to reference such a rationale and basis in developing any revised regulations.
6. The ICRP presents a number of recommendations related to the concepts of exemption and exclusion. As presently written, these recommendations are internally inconsistent, and could lead to misinterpretations. In particular, we believe that the present text inappropriately implies that exemption would only be appropriate when the individual dose is very low, when in fact, an exemption may be the logical regulatory solution even when individual doses are greater than the values given. The actions to exempt certain materials should still follow the three principles of radiation protection. At the exemption level, the effort on optimization may have reached a near optimal point (i.e., a diminishing return for further investment in the ALARA process). We also disagree with the presumption that some international values, such as those for foodstuffs following an accident, are appropriate for generic exemption. We request that the ICRP revise its discussion of exemption and exclusion.
7. We appreciate the observations provided by the ICRP with regard to the use of collective dose and calculation of health effects from very small doses. We also welcome the clarification that collective dose is mainly an instrument for optimization; i.e., for comparing radiological technologies and protection practices. However, we note that the draft document does not provide specific recommendations or guidance regarding the minimum number of individuals considered, exposure levels, or the duration of exposures that should be met before collective dose is estimated. The ICRP should clearly articulate the boundary conditions within which the calculations are valid, as well as the dose ranges for which epidemiological and cellular or molecular data provide information on the health effects associated with radiation exposure.
8. We continue to believe that the established system of protection provides adequate protection of the environment. In the introduction to the draft recommendations, the ICRP states that Section 10, “Protection of the Environment,” describes a policy approach for radiological protection of non-human species. However, Section 10 does not, in fact, state a policy. Instead, Section 10 provides a brief description of ongoing work of the ICRP. No framework for protection or assessment of exposures and pathways is proposed, and no recommendations are provided. There is also no indication of how “protection” would be defined. Furthermore, there is no definition of the relationship of protection of the environment to the more general system of protection, or how these materials would impact the current system for controlling sources. Consequently, the entire section, as presently constructed, has not been developed sufficiently for publication. We, and other stakeholders, should have the opportunity to comment formally as the assessment framework is developed. Until there is a consensus on the need for, and components of, an assessment framework, material on protection of the environment should not be published in the ICRP recommendations.
9. We believe that material related to specific implementation of radiation protection recommendations is generally more appropriate in documents published by the International Atomic Energy Agency, other international agencies, and national regulatory authorities. The discussion in Section 11, for the most part, replicates the work of other organizations and does not seem to be necessary or appropriate in the ICRP’s recommendations, and, therefore, should be deleted.
10. We believe that the statements on physician training, and risk assessments in medical exposure, should be expanded and strengthened. As diagnostic radiology procedures become more complex, and the doses from diagnostic procedures such as CT screening continue to increase, the typical reliance on generic justifications is not necessarily sufficient.
11. The draft recommendations require a thorough editorial review. There are numerous instances of incorrect spelling, incorrect usage of terms, references to publications that are not included in the reference lists, text and table numbers that do not agree, and references to documents that are yet to be drafted, being drafted, or are under review.