Protection of the Environment under Different Exposure Situations

Draft document: Protection of the Environment under Different Exposure Situations
Submitted by Terry Brock, U.S. NRC staff
Commenting on behalf of the organisation

General Comments

 The U.S. Nuclear Regulatory Commission (NRC) staff appreciates the ICRP providing the opportunity for stakeholders to comment on draft documents in an open and transparent manner.  The NRC Commission, in SECY-04-0055, addressed the issue of having a separate dose standards to non-human species and stated that: “The Commission has deep misgivings about the need to go forward with the development of a separate standard for the protection of non-human species, i.e., flora and fauna.  The NRC staff should be involved in the on-going efforts by the International Atomic Energy Agency and the International Commission on Radiation Protection on this topic to ensure that our opinion is heard.  The NRC staff should expend appropriate resources to participate in this international effort and provide comments.” 

 Consistent with NRC staff comments on ICRP 108, it is more appropriate to assess radionuclide transport from the original source, or from the licensed facility, that can potentially be released to environmental media reaching non-human biota as well as human simultaneously.  It should be pointed out that exposure scenarios particularly for major facilities or activities always assume that human is indeed interacting with all surrounding media including air, soil, groundwater, and surface water.  Therefore, considering such exposure scenarios, and considering that non-human species (e.g., ducks, trees, deer, etc.) share and interact with the same environment as the human, the concept of human protection should provide sufficient assurance for protection of non-human species. 

 As such, the NRC staff has provided specific comments nelow on the subject document for ICRP consideration.

 Specific Comments:


1.    Line 169:  A DCRL can be considered as a band of dose rate – should this criteria also include Total Integrated Dose, as the dose rate noted in Appendix 1: Table of Dose Rates and Effects for Reference Animals and Plants, appear to be inconsistent with the normally expected plant/animal occupancy times. 

2.    Line 170:  Regarding chromosomal abnormalities, as noted on line 1265-1268, “…it is the broader biological consequence that is of interest, particularly at the population level. And there cannot be any effect at the population level if no effects occur in any of the individuals of that population.”  This should be reflected within the discussion of cytogenetic effects.

3.    Line 170:  Deleterious effect – is not defined.  In some ICRP documents, it is defined as those causing early mortality, reduced reproductive success, some form of observable cytogenetic damage (the consequences of which are not known) or just some form of morbidity, such as reduced growth rate. – While some of these effects are clearly deleterious (e.g., early mortality) it is not clear that there is an actual deleterious effect associated with some observation of chromosomal abnormalities.  Are there any criteria for how long these abnormalities are observable? Do chromosomal anomalies observed immediately following an emergency condition carry the same weight as chromosomal anomalies which remain present a year or more after an acute exposure or following a long period of chronic exposure. In addition, it is not clear how the impact of these abnormalities would be assessed (i.e., first generation, 2nd generation, no observed effect).  If there is no observed impact, would these effects still be considered deleterious?  If so, why?  Perhaps a permutation of the information contained in ICRP 103 section 2.1 paragraph (30) would be useful: “Deleterious effect – one where there is an impact on the maintenance of biological diversity, the conservation of species, or the health and status of natural habitats, communities and ecosystems.”

4.    Line 170:  The term “some chance”, is overly vague.  Under LNT, there is always “some chance”.  Is there some threshold value that needs to be exceeded?

5.    Line 175:  In the discussion of the DCRLs, the “number of individuals” exposed needs to be elaborated upon. Would the size of the population make a difference if the species were already stressed or healthy? How does that relate to the subsequent introduction of “representative organisms” on line 257?” Is one always a subset of the population group of interest?  How does one account for transient or migratory species where the impacts might be manifested at locations distant from the source of exposure?

6.    Line 177:  “Exposure of significance” does not appear to be defined within this document.  I was not able to find a definition in ICRP 91, 103, 108 or IAEA STI/PUB/1229.

7.    Line 201:  Since this process is being used to plan contingency/optimization actions following emergency releases as well as routine releases, “expected situation” may be more aptly characterized as “postulated situation.”

8.    Line 213:  Define and discuss “benefits”.  What are the benefits of continued optimization to the environment and how are additional costs associated with additional efforts to optimize exposure balanced against benefits when no adverse health effects are anticipated in the exposed biota?  This concept for the environment needs additional discussion.

9.    Lines 213-216:  “For existing exposure situations, if the dose rates are above the relevant DCRL bands, the Commission recommends that the level of ambition for optimization would be to reduce exposures to levels that are within the relevant DCRL bands, fully considering the radiological and non-radiological costs and benefits of so doing.”  Since it is not completely clear how we do cost/benefit analysis for human protection, it will certainly be a very complex process to determine the benefit to be derived for a given expenditure to protect biota.

Given ICRP Report 103 cautionary recommendations on the use of collective dose, the recommendations here should be more detailed and address differences on how one would conduct cost-benefit analyses using collective doses for RAPs, and provide guidance in identifying a threshold below which no further action would be necessary.  The concept of a “cost-benefit ratio” should be introduced and defined for this purpose.

10.  Line 236:  Is “intsdcavernational” supposed to be “international”?

11.  Line 273:  There is a need to define “minimum level of ambition” given its use in this report.  How should this concept be applied in conducting cost-benefit analysis?  Would the result of a cost-benefit analysis be used to define a site-specific “minimum level of ambition”?

12.  Line 292:  The definition of environmental exposure is too limiting.  Environmental exposures are composed of natural radiation (terrestrial, cosmic) and man-made exposures to the biota in the natural environment.  If the authors wish to discuss man-made sources of radiation on the biota only, another term is needed.

13.  Lines 302-303:  Defines an existing exposure situation as one that includes natural background.  Based on lines 213-216, some optimization action may be required when radiation levels to biota from exclusively natural background radiation exceeds the DCRL.  Normal radiation protection practices are for consideration of the net (above background) dose increment resulting from human generated sources of radiation.

14.  Lines 308-315:  The definition of justification should be revised given the context of this report.  How would the benefits to society or individuals be linked to RAPs exposed to industrial sources of radiation or radioactivity? 

15.  Line 356:  Change “requirement” to “aim.”  Publication 103 articulates a number of recommendations based on aims described in the report, but there are few, if any, references to requirements, especially as they pertain to environmental protection.  The phrase “requirement” is unique to organizations like the International Atomic Energy Agency that articulate requirements with “shall” statements, whereas the ICRP promulgates recommendations.


16.   Line 370: Change “requirement” to “aim.” 


17.  Lines 386-388:  How do the values contained in existing NRC documents compare to the values referred to in the “RAP-specific dose conversion factors for a variety of radionuclides, and Derived Consideration Reference Levels”?

18.  Lines 429-431:  States that Existing exposure situations, which are defined as situations that already exist when a decision on control has to be taken, including natural background radiation and residues from past practices that were operated outside the Commission’s recommendations.”  Therefore, some optimization of “a decision on control“ action may be required when radiation levels to biota from exclusively natural background radiation exceeds the DCRL.  Normal radiation protection practices are for consideration of the net (above background) dose increment resulting from human generated sources of radiation.

19.  Lines 458-459:  This is the correct statement, and should be referenced in all other statements dealing with DCRLs.  “Environmental exposures, which are all additional radiation exposures of biota in the natural environment as a result of human activities.”

20.  Lines 555-561:  The discussion should note that remediation, by itself, may be a stressor to RAPs.  The impacts associated with such actions should be recognized as not being related to actual exposures to radiation and that the impacts may be temporary if the area is returned to its natural state or permanent if reindustrialized.  Moreover, the discussion should point out that in some instances, RAPs have thrived even in well industrialized sites and remediation would have an impact in such instances.   

21.  Lines 648-649:  It is not clear what is meant by “…A DCRL can be considered as a band of dose rate within which there is some chance of deleterious effect from ionizing radiation…”.  What constitutes “some chance”? How would one consider chance in structuring a cost-benefit analysis in justifying acceptable exposure levels to some RAPs?

22.  Line 656, Figure 2:  The placement of the DCRL bands should be based on the same biological endpoint, that is, a “band of dose rate within which there is some chance of deleterious effect from ionizing radiation occurring to individuals of that type of Reference Animal or Plant.”  Several bands are based on no information; other bands are described as effects unlikely, and others are described as very low probability of effects.    The DCRLs originally described in Publication 108 have been modified slightly - presumably due to the accumulation of additional data.  However, Publication 108 did not articulate how these bands would be used.  In this document, they are used as a basis for beginning optimization.  As such, careful scrutiny is needed as to what dose rates are ascribed to each RAP. 

23.  Lines 761-781:  How does one account for transient or migratory species where the impacts might be manifested at locations distant from the source of exposure at a specific site?  Should the process involve the conduct of species-census that is time dependent or seasonal?

24.  Lines 820-838:  The discussion on the range of possible protective measures should attempt to illustrate and bound methods of acceptable levels of protection.  For example, the relocation of some RAPs may be impractical.  Similarly, the interdiction and prevention of reentry of some fauna may also be impossible.  In such instances, the only practical means in providing some level of protection may have to rely instead on remediation, where the acceptable remediation methods would be defined by cost-benefit analyses.  


25.  Line 995:  Why is this text underlined?  The information contained in this publication (or publications 108 and 114) are not internationally endorsed criteria and standards.  They contain recommendations that may be adopted of other organizations like the International Atomic Energy Agency or the European Commission which may use this information to develop criteria and standards.


26.  Lines 1029-1097:  There are a number of European standards referenced within this section.  It is not clear how these standards comport with the relevant NRC & EPA standards and regulations.


27.  Lines 1096-1097:  Is it the expectation that the most exposed or most sensitive biota, be based on those identified in the RAP, or is it the expectation that this list would be an environment specific list that would need to be generated by owner of each potential discharge source?  If so, it is not clear as to whether the owner/operator of a site would have the expertise, obtain the right of access to adjacent properties, and resources to conduct such studies or census of local RAPs.


28.  Line 1514:  It is not clear what is meant by “, or of potential discharges in the future.”, either with respect to the time frame encompassed by the “…in the future…”. The discussion should provide more details, are future releases associated with routine (e.g., continuous or periodic) discharges associated with normal plant operations, or is it the expectation that some discharges will be associated with accidental releases in addition to normal release? 


29.  Line 1518:  It is not clear how exposure during migration or from the use of other feeding grounds can routinely be considered during the evaluation of a potential discharge scenario, nor is it clear how other potential owners of discharge pathways would be expected to interact with each other.


30.  Line 1618:  This line refers to Annex 4, but this document does not contain an Annex 4.  Is this a reference to Appendix 1?


31.  Line 1676:  Suggest changing “benthic” to “bottom” for clarity to more readers.


32.  Line 1678:  Change “pelagic” to “deepwater dwelling” for clarity to more readers.


33.  Line 1766:  This line refers to Annex 3, but this document does not contain an Annex 3.  Is this a reference to Appendix 1?


34.  Lines 2204-205:  APPENDIX 3: SELECTED EXAMPLES OF NATIONAL ENVIRONMENTAL LEGISLATION – USA should list a US Government sponsored website such as  instead of a commercial or advocacy legal entity, such as


35.  Lines 2209-2210:  In the Appendix 4 tabulation, what does the population “>1000” mean for grass and seaweed?  Wouldn’t an areal unit be more practical, such as fractional hectares, or as a productive yield, such as kg/m2?


36.  Line 2163:  Cite a reference for these four tables or state they are adapted from tables in Publication 108 (2008).


37.  Line 2163, Appendix 1:  Reconsider which dose bands LD50/30 data is placed.  The first dose band is for a dose rate > 1 Gray per day.  In most instances, the LD50/30 will be exceeded within one to four weeks.  The second dose rate band (100-1,000 mGy per day) will deliver between 3 and 30 Gy within the first month of exposure.  Would this be lethal to 50% of the exposed deer?  Might this also occur in the next dose rate band (10 – 100 mGy per day), as well?  The LD50/30 data in Table A3 appear to be appropriate for the top dose rate band with the exception of the bee larvae data which would be more appropriately placed in a lower dose band.