Protection of the Environment under Different Exposure Situations

Draft document: Protection of the Environment under Different Exposure Situations
Submitted by SSK-Secretariat, German Commission on Radiological Protection (SSK)
Commenting on behalf of the organisation

Comments by the Committee “Radioecology” of the German Commission on Radiological Protection (Strahlenschutzkommsion - SSK)

1    General Comments

The Committee “Radioecology” of the German Commission on Radiological Protection (SSK) is presently preparing a recommendation regarding the implementation of environmental protection into the German Radiation Protection (RP) legislation and RP practice. Against this background we welcome the Draft Report as an important contribution to the development of a balanced and feasible framework regarding environmental protection. However, while the draft reflects very well the up to date knowledge we feel that it overstresses this knowledge when conveying proposals. According to our opinion the proposed RP system has not yet reached a level that will help to implement it in a legislative framework. We would therefore recommend publishing the report only after major revision that includes also modifications of some conceptual approaches. The following items describe the most important aspects from our point of view:

[1]     Term “Environmental Exposure”

The term is introduced in paragraph (15) as “Environmental exposures, which are all additional radiation exposures of biota in the natural environment as a result of human activities”. The term plays a crucial role in the whole system because it excludes implicitly the “nature” from the RP of the environment. The term associates a real “environmental exposure” but means an increment. This opens a window for misinterpretation. We therefore suggest modifying the term into “anthropogenic environmental exposures” or shorter “anthropogenic exposures”. Furthermore, the (modified) term should be included in the Glossary (see below).

[2]     Terms “Derived Consideration Reference Level” (DCRL), Environmental Reference level” (ERL)

ICRP 103 proposes the term “reference level” to define the level of individual dose in emergency exposure situations or existing controllable exposure situations. For planned exposure situations ICRP 103 retains the term “dose limits” or “dose constraints” to describe the level of dose. This clear terminology will be weakened by a term that contains the word “reference” but has to be applied to planned situations too. We therefore suggest applying DCRL to emergency exposure or existing exposure situations only and to introduce an “Environmental Constraint Level” (instead of “Environmental Reference(!) Level”) as a “prospective and source-related restriction on the anthropogenic environmental exposure (or shorter anthropogenic exposure) from a source, which provides a basic level of protection for the most highly exposed Reference Animals and Plants (RAP) from a source and serves as an upper bound on the dose in optimization of protection for that source.”

[3]     Role of ERL – DCRL in the RP system

  • According to the Draft Report paragraph (38) the lower boundary of DCRL shall be used as starting point “for optimization of environmental exposures in planned exposure situations … within a given area during the planning of controls to be applied to a source”. Consequently, this dose rate value has to be interpreted as a dose constraint. But in paragraph (38) another dose constraint, the ERL is defined. This is justified by the “possibility of multiple sources affecting the same animals or plants, or for any residual exposures (exposures) arising from previous sources affecting the same animals and plants”. This makes the system rather complicated and may result in confusion.
  • If a safety margin is to be part of the RP system, the ERL below the DCRL should be considered as the (only) dose constraint and should be the starting point of optimization.
  • Even if the exposure is within the DCRL band, the Draft Report considers that the optimization principle should nevertheless continue to be applied, assuming that the costs and benefits are such that further efforts are warranted (paragraph (42)). However, there is no guidance on the dose rate below which further reduction of exposure is not justified and the optimization process should reasonably be stopped. Is the lower boundary of the DCRL a suitable dose rate criterion?

[4]     Representative Organisms (RO) - RAPs in site specific assessments

In ICRP 103 the RAPs were introduced as a conceptual tool to quantify the impact of ionizing radiation on populations and ecosystems. ICRP 103 states that “With the exception of mammals, however, there is a general paucity of information upon which dose-response relationships can be established that would enable sensible conclusions to be drawn, particularly with respect to the relatively low dose rates likely to obtain in most exposure situations.” The current report does not give any new information, which led to a significant modified assessment. But it states (line 260 ff): “Nevertheless, differences between such biota and the RAPs should be quantifiable, in relation to their basic biology, dosimetry, or radiation effects, and such differences need to be noted and taken into account. The extent to which such factors then need to be applied, and their relevant impact on the final decision, will depend on the nature of the implementation and application of the planning process relevant to protection of the environment. Because other regulatory bodies are likely to be involved, such as those responsible for wildlife management, it is essential to have a clearly set out logical link between any radioactive releases and potential risk of biological effects (for which the RAP framework should be a starting point) and a clearly laid out strategy by which the relevant stakeholders can be engaged in the decision making process.” All these statements open a wide range of interpretation and uncertainty. We are afraid that this “scientific approach” will result in problems in legal implementation. We would like to illustrate our assessment with the paragraph (j) of the executive summary. There it says in line 257 f: “Because the RAPs are, by definition, points of reference, it is also necessary to identify Representative Organisms relevant to each evaluation.“ Here we agree, because it is necessary to consider different environments (deserts should not require consideration of fish and ducks and marine environment need no deer). But the next sentence of paragraph (j) (and the corresponding ideas given in Chapter 4.1) try to expand the approach of RAPs to the real complexity of ecosystems and overstresses the reliable basics. By the opening clause (line 257/258) “These may well be extremely similar to RAPs, or different” the selection of quite other types of organisms will be enabled. In the Draft Report it is stated (line 267) that “it is essential to have a clearly set out logical link between any radioactive releases and potential risk of biological effects (for which the RAP framework should be a starting point) and a clearly laid out strategy by which the relevant stakeholders can be engaged in the decision making process.” But referring to the statement in ICRP 103 we believe that the logical links cannot set out with the necessary confidence. Therefore, in order to develop a feasible system of RP we strongly suggest using this approach as a convention. The RO should be selected only from those RAPs that really occur at specific locations. We would like to emphasis that such convention will not reduce the set of organisms to a few very specific species if ICRP 108 is applied and “Deer” is read as “a large terrestrial mammal”, “Rat” is read as “a small terrestrial mammal” etc. We believe that the following recommendation (paragraph 44 line 775) leads to practical problems: “Where this is not the case (and it should be noted that it is not currently possible for the present range of RAP types to be increased appreciably) then attempts should be made to consider to what extent the Representative Organisms differ from the nearest RAP, in terms of known radiation effects upon it, basic biology, radiation dosimetry, and pathways of exposure.” Such attempts will open the RP systems to more or less scientific methods and approaches and could result in a misuse of the system. Scientific methods and approaches are necessary for the further progress, but they should be clearly distinct from a regulatory approach as we understand the ICRP recommendations. We have to point out that ICRP has stated (ICRP 108 para (230)): “it is not currently possible to provide recommendations regarding how to perform extrapolations that have general applicability in relation to radiation effects, and thus each case has to be considered carefully on its own merits.” For that reason we suggest a clarification that for the purpose of legal implementation ICRP believes that the standards of environmental control needed to protect RAPs ensure that other species and specific ecosystems are not put at risk (cf. ICRP 103 paragraph 362).

[5]     Dose – Effect, Relative Biological Effectiveness (RBE)

  • The Draft Report suggests (Annex A Appendix 1) numerical criteria for dose rates as a yardstick for the protection of non-human biota. However, relevant information required to calculate the dose rates of Reference Organisms and Representative Organisms, is still missing. In particular there is a lack of RBE values. The Draft Report provides no guidance on how to deal with this situation. Without an unambiguous definition of RBE values the RP system is not applicable!
  • If for simplification all RBE are arbitrarily assumed to be 1, the dose rates of Reference Organisms will be underestimated. It is unclear, how the Tables in Annex A have to be read and used without any clear definition of RBE, in particular “in communicating with stakeholders on the possible effects and implications of releases of large quantities of radionuclides into the environment as events unfold”.

Taking into consideration the obvious difficulties to derive confidential RBE we would suggest to use at the present level of knowledge dose as a convention for quantification of exposures and in order to establish a system of RP. This does not mean that any links and reprimands to effects should be eliminated. But a clarification that effects have been used by ICRP to derive a proper set of reference and constraint levels would help to avoid speculative discussion in the application of the recommendations. Otherwise we see the danger that ICRP sets standards in a field that is under scientific research and by far not clear enough for regulation. We believe that it will be much easier to expand the scope of a recommendation in future and set stronger restrictions after research has obtained more precise results than to reduce the scope of recommendations later.

[6]     Site

The Draft Report uses several times the term “site”. For instance the Representative Organisms (RO) are defined in line 338 as “A particular species or group of organisms selected during a site specific assessment.” In Line 697 it is stated for emergency exposure situations “to consider the environmental consequences of possible accidents at a site …” and in line 810 “compliance with national pollution control licensing requirements relating to particular industrial practices or to specific sites or areas” is called.

All these statements are rather vague. The question arises how the site of assessment has to be related to the radiation source and the doses that have to be derived for RAPs. Because RP of the environment means a protection of populations (line 774: “the local habitats or ecosystems”) a “hot spot” of contamination or another locally restricted source should not be considered as a “site”. A clarification of ICRP is needed. Eventually the term “site of assessment” should be introduced and defined. Currently, it could be read that ICRP recommends defining the site of an assessment in such a way that the population numbers of RAPs given in Appendix 4 shall be used as a reference in order to estimate the extension of a “site”.

[7]     Radio-eco-toxicology and chemical eco-toxicology

The Draft Report refers in Annex A extensively to the “common” environmental protection and in this connection also to the concepts and objectives of the chemical eco-toxicology. However, the Draft Report provides no clear relations between the proposed dose levels (DCRL, ERL) and eco-toxicological approaches like PNEDR (predicted no-effect dose rate), NOAEL (No Observed Adverse Effect Level); LOAEL (Lowest Observed Adverse Effect Level). A clarification would be strongly desirable. Otherwise the RP system tends to develop an own system that is not harmonized with the eco-toxicology.

2       Specific Comments

[1]     We would like to point out that the Glossary is incomplete. The following terms need definition: ERL, dose, “Environmental exposures” (now defined in paragraph (15)). Eventually, the term “site of assessment” should be defined.

[2]     The background dose rates given in Appendix 1 are very unspecific. It is unclear what RBE values and what range of natural activity concentrations have been used for deriving these values. If a range up to 1 Bq/g U-238 or Th-232 is considered as natural background (cf. IAEA) than the dose rates given in Appendix 1 seems to be too low.

[3]     The background dose rates in Appendix 1 do not comply with the term “environmental exposure” as used in the Draft Report. If environmental exposures are referred to additional exposures resulting from human activities, then the background has to be exactly zero. If the total dose rates are meant, then this should be clearly specified (for at least in a footnote).

[4]     In Appendix 3 the German legislation can be cited as: The German Radiation Protection Ordinance contains a general formulation concerning the protection of the environment in its § 1 “The purpose of this Ordinance is to regulate principles and requirements of preventive and protective measures which apply to the use and effects of man-made and naturally occurred radioactive substances and ionizing radiation in order to protect man and the environment from the harmful effects of ionizing radiation.“ Specific rules of guidelines on how to apply this in practice are not yet developed.

3       Spelling mistake

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877      situations might well in the furure be integrated in a relatively simple way, based ….