|Comments on the ICRP Task Group Report: The Concept and Use of Reference Animals and Plants for the purposes of Environmental Protection
Prepared by the Environmental Subcommittee of the US Interagency Steering Committee on Radiation Standards (ISCORS)
The following comments represent a consensus of views from participating members of the subcommittee representing the Nuclear Regulatory Commission (NRC), the Environmental Protection Agency (EPA), and the Department of Energy (DOE).
We are pleased to participate in the open process of consultation offered by the International Commission on Radiological Protection (ICRP).
• The draft recognizes that the approach discussed in the report cannot reflect the full range of biological diversity, or provide a general assessment of the effects of radiation on the environment as a whole. A safety case that the current system of regulations (i.e., if humans are protected, then so is the environment) is an unacceptable method or has weaknesses has not been demonstrated. To the contrary, the empirical evidence demonstrates that the environment is being adequately protected by the current system of radiation protection. This fact is recognized in paragraph (6) of the draft publication ("Thus it is probably true that the human habitat has been afforded a fairly high level of protection through the application of the current system of protection.”). The potential burden to regulators and industry associated with developing and implementing such a new system is not balanced by any increased protection to non-human species. An assessment of where, under what exposure scenarios, and to what degree the current system of radiation protection for humans is not protective of non-human species is warranted.
• Page 9, section (8), last sentence: “The question of whether one should protect individuals or populations from harmful effects of radiation in any particular circumstance, however, is not an issue of direct concern to the Commission.” Comment: This question is indeed of significant importance as it may impact the manner in which we determine if plants and animals are negatively impacted by radiation. In general, for both technical and regulatory applications in the U.S (e.g., Comprehensive Environmental Response, Compensation, and Liability Act ), it is the population that is used to determine if impacts have occurred; not the individual. Current radiological and non-radiological methods and the expected safe levels of exposure are intended for use in protecting natural populations of biota, rather than individual members of a population. The ICRP will need to address this question, or identify the appropriate organization that is best suited to address this question. This issue will impact some of the ICRP’s proposed approaches in the use and interpretation of dose estimate results from application of reference organisms relative to dose rate guidelines, effects benchmarks, increments of background concentrations, or other measures of effects to biota ultimately selected to determine “risk” or harm to non-human species.
This approach also appears to be inconsistent with the ICRP's aim to safeguard the environment by reducing the frequency of effects likely to cause early mortality or reduced reproductive success to levels where they would have a negligible impact on conservation of species, maintenance of bio-diversity, or the health and status of natural habitats or communities. The draft publication also notes that a large number of animals and plants are already afforded protection at the level of the individual and that it would be inappropriate to provide advice that could not be used in such legal context. While we recognize that there are appreciable scientific difficulties in estimating the impact on communities of species and the ecosystem based on impacts to individual species, we believe that affording every individual the same level of protection as threatened and endangered species is problematic.
• As stated in previous DOE and U.S. federal agency consensus comments provided to ICRP by ISCORS, consideration should be given to a graded or tiered approach, to include screening levels, to cost-effectively eliminate those situations which pose no harm. In this regard it is not clear how the current ICRP document on reference animals and plants would be used to implement such an approach.
• Paragraph 51.
The proposed set of reference animals and plants remains overly complex and is being advertised as “…..the development of a small set of Reference Animals and Plants, plus their relevant databases, for a few types of organisms that are typical of the major environments.” (page 10, section (11), lines 4-6).
By including the various stages of development, the original set of 12 reference plants and animals seems to be expanded by 3 or 4 times. Thus the reference system is much more complex than seemingly first described.
• Paragraph 13. We disagree with the approach of comparing derived consideration levels (dose rates) for reference animals and plants to normal natural background dose rates of the reference organisms. Natural background for humans varies by location around the world because of many factors including local geology and elevation. Natural background will vary even more significantly among other species. For example, terrestrial mammals will have vastly different natural backgrounds than fish or even earthworms. Adding to this the variability of natural background globally, the approach proposed by the ICRP will make practical evaluation exceedingly complex or potentially meaningless.