Overall we find that there is a lack of clarity about how the RAPs and DCLs are intended to be used within an assessment (or if the Committees view is that we are near the stage when they can be used). The report needs to clearly describe how the concepts presented are envisaged to be used within an assessment preferably in one summarising chapter.
We acknowledge that the Committee has stated that this is very much a work in progress and (e.g.) the DCLs are a first step. The report needs to discuss a prioritisation of what further work is required. Moreover, the Committees reservations with regard to this being a work in progress need to be clearly stated ‘upfront’ (and in summary/conclusions). The outputs of the ICRP are held in high regard and without such clear reservations being expressed there may be a tendency for some to take the view that the suggested DCLs are THE numbers to use in assessment.
2. Reference Animals and Plants
We recognise why the RAPs are defined as ‘hypothetical entities’ and accept the ‘what they are not’ discussion within Para (29). However, we question the merit of then defining then to a fairly high degree (including 30 pages of Appendix A) down to the level of what time of day a rat feeds. Is all of this detail helpful or does it promote the type of comment ‘the RAP do not represent animals in my country’.
Are all RAPs defined at the same taxonomic level (trout rather than salmonid?)?
Table 1 assessing criteria for selection of RAPs is misleading with respect to ‘data on radionuclide accumulation’. For instance, there are few (if any) data available for ‘bee’ and ‘rat’. Whereas data for grass (classified as medium) must be amongst the most abundant.
3. Natural background dose rates?
Paragraph (9) states: ‘It was further considered that it would be helpful to decision making if this information was set out in terms of multiples of the natural background dose rates typically experienced by each type of animal or plant, in the form of Derived Consideration Levels.’ – whilst a generic background exposure rate is presented on Tables 8- 11 is this objective actually met?
Para(344): There are more recent data, specifically considering the ICRP RAPs, which would improve this discussion.
Table 8: Is a generic value of <0.01 consistent with Paras(343)-(344)?
Para(65) states ‘ It should also usually be possible to obtain direct radionuclide concentration data in order to estimate doses from internal sources’. We think this statement is incorrect, for instance, such measurements would not be available for assessments associated with new facilities nor would they be a desirable requirement for screening level assessments.
The work of the EMRAS Biota Working Group and the EURATOM PROTECT project (amongst others) has demonstrated that the transfer components of the available assessment models contribute most to the uncertainty in outputs. Therefore, Committee 5 needs to give due weight to their activities in establishing transfer parameter databases and also effectively collaborate with other groups working on this issue (i.e. IAEA initiatives). We consider that it is highly likely that data will not be available for many of the RAPs as defined.
5. Chapter 5 Radiation effects
We suggest that this chapter needs a thorough proof reading as some of the observations made do not seem credible. For instance, Para(153) states that a soil concentration of 14 Bq/kg of Sr-90 resulted in significant reductions in the number of deer and elk! Similarly, Para(278) states that 1 Bq/kg of Sr-90 (in what is not noted) reduced brown frog reproduction success to 45-90% of control levels?
Para(335): ‘As stated in the introduction, there are many data to refer to, but little guidance with respect to their reliability, consistency, interpretability, or utility.’ Should not an assessment of data reliability and utility have been an objective of Chapter 5?
A number of other groups are currently working on analysing the available data on radiation effects which is not mentioned. Has there been interaction with the on-going review by UNSCEAR (due end of March 2008) during the process to derive DCLs?
6. Derived consideration levels
Tables of DCLs follow on from the c.40 page summary of radiation effects data. However, there appears (in Chapter 6) to be no transparent link between the proceeding review and the proposed values. Also there is no discussion of how the DCLs would meet a goal of protecting populations.
7. Dose conversion coefficients
The terms ‘dose conversion factors’ and ‘dose conversion coefficients’ are currently both used. Needs to be made clear that the dose conversion coefficients presented are unweighted in Appendix C tables.
A presentation of the RAP report was made by a member of C5 at the recent EURATOM PROTECT project workshop in Oslo. The workshop report contains a number of comments from attendees on the RAP approach (see http://www.ceh.ac.uk/protect/pages/documents/PROTECTOsloworkshopWP2_3reportFinal.pdf).