The Swedish Radiation Safety Authority (SSM) welcomes the integration of environmental protection within the ICRP system of radiological protection. This report is an important step forward in the world wide evolution of environmental protection regarding ionizing radiation. The inclusion of environmental exposure as one of four types of exposures, besides occupational, public and medical exposures, together with recommendations on how to consider justification, optimization and dose limits regarding environmental exposure in isolation and in combination with the other types of exposure will facilitate a more thorough consideration of radiological protection in all exposure situations.
General comments
Consistency within the ICRP system. While ICRP strives to incorporate environmental protection within the existing system of protection and make it a natural part of that system, with much the same conceptual philosophy and practical handling regarding protection of the environment and protection of human health, there are still conceptual and terminological differences that might cause confusion in the understanding and implementation of the system (see comment 2 and 3). SSM suggests that the system is reconsidered in order to avoid these differences, or otherwise to more clearly describe and justify them.
Bands of dose rates. One example of a conceptual difference is the relation between suggested bands of dose rates and point values of dose rates used within the system. For human protection ICRP suggests bands of dose rates from within which it is recommended that point values of dose constraints or reference levels are chosen depending on source and situation. For environmental protection, on the other hand, the band of dose rates (DCRL) has no clear function as a band in the report. Instead it is the point values bounding the band that is more or less directly used in the system, the lower for derivation of the suggested ERL values used in planned situations, and the upper as an equivalent to a preset reference level in existing situations. There is thus a significant conceptual difference in setting “reference levels” in existing situation. SSM recommends ICRP to more clearly explain and justify why “reference levels” in existing situations should be preset for environmental protection (as the upper bound of the DCRL) rather than being set depending on the situations, as is done for humans.
Terminology. The terminology regarding humans includes dose constraints in planned situations and reference levels for existing and emergency situations. It might thus be confusing introducing environmental reference levels (ERL) for planned situations. As both dose constraints and ERL are supposed to be starting point of optimization, and normally are fractions of something else (dose limit and lower bound of DCRL respectively), and as both types of values are described as possible to exceed without necessarily formally be regarded as regulatory infraction, the ERLs are easily interpreted as in effect being environmental dose constraints, (EDC). SSM suggests that ICRP clarify whether, and explain why or why not, the intention of the ERL is to function as dose constraints or not. If the use of ERL is intended to be the equivalent of the use of dose constraints, this should also be reflected in the terminology. If not, the name environmental reference level is still recommended to be reconsidered. The upper bound of the DCRLs are described as to be used in existing situations “as criteria to mitigating environmental exposure, in the implementation of optimization, just as reference levels are used for mitigating individual exposures for humans”. If the term ERL is to be used it might thus be more intuitive to use the term ERL for the upper bound of the DCRL.
Environmental dose constraints? As noted in comment 3, it is possible to interpret the report as ICRP recommend that, for a planned situation, values are set that in effect are the equivalents of dose constraints for other organisms than humans. SSM notes that scientific knowledge on which to base such values still is improving and that it is possible that the DCRL and hence the ERLs are adjusted an order of magnitude up or down. Although dose constraints are reviewed and adjusted according to new knowledge also for humans, it is of extra importance that newly introduced values are not changed too soon, especially if they have direct impact on regulation. SSM thinks it is important that ICRP considers the probability of frequent and soon-coming adjustments of their DCRLs and includes a discussion on this and justify that the knowledge base is mature enough if the ERLs are to be used as environmental dose constraints.
Severe effects levels. The need, meaning, appropriate method of derivation, and use of “Severe effects levels” have been discussed for example within the EU project PROTECT, and further considerations of these levels are welcomed. Whether such levels should be directly included in the ICRP system of protection is less evident. There is no equivalent for the protection of humans, although the potential severe impact to humans would be included in the process of siting of sources just as this report recommend that potential environmental impact should be considered. The current report does not clearly explain how such values should be applied. What is the implication of potential releases giving rise to dose rates above these severe effects levels?
RAPs and representative organisms. The ICRP system builds on the assumptions that it is possible to assess environmental protection regarding ionizing radiation by assessing single species based on dose-effect responses on individual organisms. While SSM believes that such a system is justifiable and a practical way forward, it does not consider all aspects of environmental protection. SSM suggest that the ecosystem approach, interaction between species and relations between effects on individuals and population effects is further discussed and referenced within the report.
Optimization. SSM suggest that ICRP further clarify how environmental protection is recommended to be dealt with within the optimization process, especially when considering “the inter-relationships amongst the different categories of exposure”. Is there, for example, a lower environmental dose rate level below which it is recommended that no further consideration is given to environmental exposure in relation to other types of exposures?
Comments on specific part of the text
983-1058: Suggest to clarify if and when the text is referring to environmental protection in general and if and when it is referring to protection against ioniszing radiation in particular.
1533: It is stated here that “it is…not possible to say…that measures to protect individual organisms would also necessarily protect the population” which seems to contradict line 1266 ”there cannot be any effect at the population level if no effect occur in any of the individuals”. The intended meaning of paragraph A45 is not fully clear to us, and we suggest that it is further clarified.
1723: Excessive punctuation.
1790: “External” is mentioned twice although it should be “internal” at one of the occasions
1848-1869: this sections duplicate to a large extent the text of lines 1212-1237
1995-2010: This section duplicates to a large extent the text of lines 1199-1211