Two important choices for the general internal dose assessment methodology should be done from C2 ICRP members. They relate to acceptance of the “Dose per unit content” methodology and of the “constant chronic intake” approach for routine monitoring. In my opinion the present version of the document puts together parts written by different authors, but does not have a complete agreement on these two items thus producing confusion to the reader. I think that a unique, well defined procedure would be the principal aim for a guidance document.
Routine monitoring approach
It must be clarified if C2 of ICRP supports the use of the hypothesis “T/2” (as the ICRP 78) or “constant chronic” (as indicated in for routine monitoring in Ann. F). Mixing the two approaches as it is in the current version of the document is confusing. After making such decision, in the whole document, tables and graphs must be consistent to this choice, for all quantities (content per unit intake, dose per unit content, content per unit dose). In Annex D regarding dose assessment with the dose per unit content approach it is indicated a “Mid-point dose” (Page 6 Ann. D) that conflicts with the “constant chronic” approach of Annex F. On the contrary the values for day 14 in table 27.10 for routine monitoring of U-234,235,238 that, adopting the “T/2” approach, should be equal to those reported for day 7 in Table 27.8, have been calculated with the “constant chronic” approach.
On the other hand the values of Mc are calculated with the “T/2” approach for routine monitoring in eq. 7.1 and also the numerical value in table 7.1 are consistent with this approach.
Dose per unit content approach
If ICRP supports the Dose per unit content approach inside the guidance document a clear indication must be provided in each part of the document. Consequently if the intake evaluation can be considered of practical no importance, also the definition of ALI should be cancelled.
Paragraph 5.8 page 45. For wound modeling: I do not agree to provide indication on wound excision on the base of a limit of 20 mSv as Committed Effective Dose (CED).
In the present version of the guidance the wound excision is determined from dose assessment during stages 7A (fig G7) and 7B (fig. G8). In stage 7C if the evaluated CED exceeds 20 mSv it is foreseen the possibility to re evaluate the retained activity in the wound.
I do not support the idea that in a guidance document on dose assessment a procedure of excision [that I consider to be under the responsibility of the Approved Medical Practitioner (e.g. in EU Directive 96/29 art. 36) as a decontamination measure (e.g. DTPA treatment)] is indicated. To better evaluate the part of the wound material that can be absorbed into the systemic circulation (to evaluate the CED via the excretion curves per unit uptake as those presented in figures 3.8 and 3.9) the excretion measurement could better indicate the amount of material in the different physical and chemical forms that is available for the absorption ion the blood. The excised material can provide isotopic ratios and physical-chemical composition, and the direct wound measurement (if the efficiency parameter is correctly applied) can provide the upper limit of the amount of what can be absorbed inside the blood circulation. For the intake evaluation, i.e. for the material that actually has been made available for absorption in the blood stream I will be more confident on excretion and organ retention data.
For the same argument it would be useful also read the Appendix H of the application of the new wound model, when it will be available, considering also some practical examples of dose assessment from intakes via wound. .
Use of the guidance document
To actually perform a dose assessment it is foreseen always to use
-the Guidance document for the flow charts and the procedure, mainly the Chapter 8 and Annex G) plus
-the OIR document (for general tabulations) and
-for particular evaluation (e.g. the delivered dose at different time) or for planning procedure (content per unit CED) also the CD-ROM.
Is there a simpler way to provide information or a summary to be given to the assessor? One aim of the IDEAS guidelines has been to provide indication for dose assessment with simple tools, at least up to stage 5B, 6B or 7B i.e. before trying to change non-systemic or systemic model parameter values.
I strongly support the idea that up to these stages the internal dose assessment should be performed only using spread-sheets and tabulations provided in ICRP documents or having all tabulation on a unique CD.
Page 67 approximately at half page: mistyping (Chapter 9); must be (Chapter 8)
Page 7 “Tables and figures”: correct the values for SF for faeces with those reported in J.Marsh et. al. paper at Montpellier 2006 workshop.
Page 15 “Tables and figures”: provide figures 5.1 and 5.2.
Page 20 “Tables and figures”: Provide table/s of retention and excretions curves per unit intake in the wound for the default types of any element (e.g. for Caesium Soluble Weak and Particle categories) after Table 27.10 and before Table 27.11.