Radiation protection principles of NCRP

The current recommendations of the National Council on Radiation Protection and Measurements (NCRP) relative to ionizing radiation are based on radiation protection principles that developed historically as information about radiation effects on human populations became available. Because the NCRP Charter states that the NCRP will cooperate with the International Commission on Radiological Protection (ICRP), the basic principles and recommendations for radiation protection of the NCRP are closely coupled with those of the ICRP. Thus, the fundamental principles of justification, optimization, and dose limitation as initially stated in ICRP Publication 26 have been adopted and applied by the NCRP in its recommendations. ICRP and NCRP recommendations on dose limitation for the general public and for occupationally exposed individuals are based on the same analyses of radiation risk, and, while similar, there are differences reflecting the aspects of radiation application and exposure circumstances unique to the United States. The NCRP has recently extended its guidance to address exposure to individuals engaged in space activities. Several reports have been issued or are in preparation to provide recommendations on dose limitation and the development of radiation safety programs to apply the radiation protection principles in space activities. The biological basis for these recommendations is provided in these and accompanying NCRP reports. Recommendations for the application of basic radiation protection principles have been made in many reports over the years. Those that are most current appear in approximately 50 reports published in the last 15 y. These address radiation safety practices in industrial and medical institutions, control of radionuclides in the environment, protection of the public, and assessment of radiation risk. Some of the aspects of these recommendations will be discussed. Current recommendations related to radiation safety practice are based on the principles and dose limits specified in Report No. 116. The limits are based on estimates of the risk of fatal cancer and an assessment of the risk that should be tolerated by workers who are occupationally exposed and by the general public. These levels of risk are related to other risks that individuals accept in their lives. Looking to the future, one might consider other directions that the NCRP could take in developing radiation safety recommendations that are still based upon the stated principles, such as relating dose to loss of life expectancy instead of fatal cancer risk. It may also be that the principles of justification, optimization, and dose limitation should be reconsidered. For example, the NCRP may make recommendations about the relationship of radiation dose to various biological effects or outcomes and the resulting estimates of risk, but not specify dose limits. This would relieve the NCRP of the necessity to speculate about acceptable risks. One can also imagine that the principle of justification could be applied not only to the introduction of a new source of radiation, but also to the removal of an existing source of radiation, i.e., the idea of justifying decontamination efforts. It is clear that as we move into the 21st century there will be a continuing need for the NCRP to identify the principles upon which radiation protection is to be based and to provide guidance on the application of those principles for the many beneficial uses of radiation and radioactive materials in society.