Comments on the ICRP draft document “Protection of the Environment under Different Exposure Situations” from Olga German and Synnöve Sundell-Bergman, VattenfallAB as of 11 October 2012.
The draft document is understood as completing the ICRP´s ongoing work on compassing the objective of environmental protection by preventing or reducing frequency of deleterious radiation effects. The efforts and concern on the protection of the environment are in line with the general interest of the society to consider protection of the environment not only in terms of maintenance of biological diversity, conservation of species, and health and status of natural habitats, communities and ecosystems but also as a part of the protection of man and society itself.
It is an ambitious document that still lacks essential information for it to be appropriate in the context of legislative frameworks. In addition, the suggested approach by the ICRP is unnecessary complicated while the question remains whether the environment will be better protected with the current ICRP approach.
The aim to have similar approaches for protection of humans and the environment may be praiseworthy but there are obvious differences that need to be recognised. Concepts and terminology used in the human framework may not be directly applicable in the suggested framework for environmental radiation protection. This has to be clarified by the ICRP especially in relation to the optimisation principle.
The detriment and target of concern
For protection of the environment the main target of concern, as stated in ICRP 91, relates to ecosystems and populations and not individuals. The implications of this, in view of endpoints, dose and dose rate levels etc, are not properly addressed in the draft document. In fact there are also some confusing remarks; in para. A22 it is stated that there can not be any effect on the population level unless there is an effect at the individual level (see also A70). But in para. A45 it indicates that the population impact may occur irrespective of impact on the individuals.
The absence of information on effects at higher organisation levels in the environment is acknowledged, but ICRP still believe that the information presented in ICRP 108 is sufficient to provide guidance. This results in skewed balance with a lot of focus and advice on individual-related matters, while the main topic for the environmental radiation protection, population and ecosystems is shrouded in mist.
It would be advantageous of ICRP to instead of referring to own produced papers and data, rely on knowledge that have been evaluated within a broader scientific community e.g. UNSCEAR in analogy with human radiation protection. There is a considerable amount of valuable judgement involved in the derivation of DCRLs which needs to be thoroughly reviewed in a larger scientific context.
It would also be appreciated if ICRP provided some kind of recommendations or wishes for research in areas of interest than simply pessimistically stating that it is “unknowable” (A24).
This term environmental exposure is introduced in para. 15 to add to the other exposure categories as applied for protection of humans while the meaning seems to be exposures of biota to radionuclides in the environment However, the definition is confusing and needs clarification. Natural radionuclides may cause exposures due to human activities, shouldn´t they also be considered? This is relevant especially in view of the RBE. Medical activities may cause releases to the environment - should that be included? This is not mentioned in the draft document. In an existing exposure situation people are exposed to radionuclides in the environment – are they included?
Dose constraints in optimization are source related and therefore there is need to give clear definition of radiation source and also its limitations. It should be emphasised that a nuclear reactor (or site) may contain several radiation sources for which constraints are developed. In relation to this it also needs to be awareness that some organisms (and RAPs) in the environment normally may not be exposed to multiple sources (see para.38) since their home range is quite narrow.
DCRL and ERL
How these reference levels should be used in the optimization process is confusing (see para. 36 and 38).
If the ERL should be the dose constraint in an optimization process what is than DCRLs – criteria?
For emergency exposures the scale of effects focussing on is not reflected in derivation of DCRLs (see para 39). But surely the aim of protection despite exposure category must ultimately be the same, although the reference dose levels may differ due to the circumstances.
To identify representative organisms under specific circumstances may be helpful since the environment is highly variable. But to make relations to RAPs in terms of radiation effects, dosimetry and exposure pathways as stated in para..44 will among other things in an EIA create interpretation problems as well as raise the uncertainties. The reason for doing this does indicate that the DCRL and RAPs in reality are to be regarded as dose limitation systems despite the denial by ICRP.
The radiation discharges from NPPs are regulated by dose and/or authorised discharge levels and to change this in future as indicated in para. 52 to measurement in the environment is a step back since the primary aim of ICRP is to contribute to the protection of man to the negative effects (synonymous with the dose) of radiation. For protection of the environment there are certainly other methods that could be envisaged with a much clearer ecosystem perspective. It should also be recognized that significant amount of resources may be required to make these complicated assessments proposed by the ICRP..
Radiation effects (Annex A and appendix 1)ICRP
ICRP implies, in the draft document, that the present knowledge on the detriment for environmental radiation protection is sufficient to propose a framework on the environment protection. However, some essential factors for sound assessments are still missing. Thus, the meaning of an effort to make assessments on an individual level for a few (unrepresented?) organisms to demonstrate protection should be questioned. There is a need for guidance on extrapolations to relevant targets; concurrently, the differences in the radiation quality (RBE) should be considered before this system is ready for a practical application in radiation protection legislations.
These issues are not easy, but ICRP has the responsibility to provide recommendations to the scientific community on why and where more and better knowledge are required.
Some specific remarks
Executive Summary It is a reasonably fair summary. It should however at the end of the summary more clearly emphasize the need of more measurements to decrease present uncertainties in experiments and assessments that are identified and discussed.
Glossary – needs to be extended; ERL, RBE, dose environmental exposures etc.
385 . Relevant radiation effects – relevant for what?
589 – Release is significant – what levels?
712 – Comparison between severe effect levels in case of radionuclides to the DCRL band should be done explicitly for relevance.