|Comments on the draft of the new recommendations released in June 2006
A. Not complete consolidation of practice and intervention
In this new draft ICRP intends to apply the same radiation protection approach to “practice” and “intervention.” However, there are several paragraphs that are not consistent with the new approach.
A1. Paragraph 185: This paragraph states that a set of principles apply equally to planned, emergency and existing situations. However, the principle of limitation of maximum doses is remained as one of the principles but can be apply only for planned situations. It is not self-consistent in the initial statement in the paragraph. If ICRP wants to consolidate practice and intervention with one set of principles, then the dose limits should be replaced with the dose constraints.
A2. Paragraph 219: In this paragraph the ICRP states that “Also for existing exposure situations, the Commission recommends that optimisation of protection of the public should be performed if the projected individual dose to the public exceeds a level for which some form of intervention with protective actions would be warranted under almost any circumstances in order to reduce the level of exposure as low as reasonably achievable below the constraint.” in paragraph 219. The statement is not correct. It is mentioned in other paragraphs in this draft that optimisation is applied to reduce the dose from the constraint. Therefore, it is not appropriate and rather confusing to describe that optimization should be performed if the dose exceeds a constraint.
A3. Paragraph 223: In this paragraph it is mentioned that “In emergency and existing exposure situations, where exposures are not planned, constraints should be viewed as a level of ambition and not as a mandatory level which must be achieved.” It is not an appropriate expression because in planned situation, the constraint is not considered as a mandatory level. Their explanations should be consistent.
B. Action levels and constraints
Constraints and action levels are mixed up in the new draft. It is necessary to clarify the difference between the two, since they are not the same.
B1. Paragraph 279: This paragraph should be rewritten taking care of the difference between the constraints and action levels. Especially the underlined parts in paragraph 279 shown below are not appropriate. “These action levels are effectively constraints i.e., levels of aspiration often set by national authorities and not a mandatory level which must be achieved. In circumstances where doses exceed the value of constraints, optimised protective actions should be taken to reduce doses.”
B2. Paragraph 301: The ICRP states in this paragraph that the Commission retains the relationship between the constraint of 10 mSv given in Publication 65. It is not the right statement, since 10mSv in publication 65 is not the constraint but the action level. They should not be confused. In addition, quotation of 10mSv as a constraint is not appropriate, since three bands of dose range are proposed in the draft to decide feasible dose constraints in each country. The 10mSv is not consistent with the dose range of 1 to 20 mSv in which the exposure to radon is considered.
B3. Paragraphs 330, 348: Intervention levels are introduced in these paragraphs. It is not necessary to introduce “intervention levels”, since the intervention is no more used. Introduction of unnecessary term works just the cause of confusion.
The description of justification is better than before. A little more expansion of the justification concept in the recommendations might be required.
C1. Paragraph 188: It says in this paragraph that there are two different approaches to applying the principle of justification in situations involving occupational and public exposure. We believe that one more approach should be introduced in applying the principle of justification during the process of selection among options with and without use of radiation. In this process its risk derived from the use of radiation should be taken into consideration as an input for a better decision although it is not necessary to cover ethical or economic aspects.
D1. Paragraph 221: In this paragraph the ICRP states that “The optimisation of protection is a forward-looking iterative process aimed at preventing exposures before they occur.” This is not true in the case of existing situation where the exposure has already occurred. Therefore, following correction might be necessary.
Revised paragraph 221: In the case of planned situations, the optimisation of protection is a forward-looking iterative process aimed at preventing exposures before they occur.
E. Collective dose
Abolishment of matrix for the expression of collective dose is a better decision, since matrix is not a familiar way, nor easy to use in a regular single line sentences. Rather we had proposed a vector for that purpose, since it can be fit in a single line.
F. Expression for high dose
In the new draft it says in paragraph 144 that “in cases of high doses that could give rise to tissue reactions the use of effective dose is completely inappropriate.” Moreover, it says in paragraph 93 that “in such situations, doses should be evaluated in terms of absorbed dose (in gray, Gy).” On page 8 in the draft of BASIS FOR DOSIMETRIC QUANTITIES USED IN RADIOLOGICAL PROTECTION it says that “if high-LET radiations are involved, an RBE-weighted dose, RBE•D (Gy) may be used in this situation.”
We propose again the use of “GyEq” for the region of high dose where we expect deterministic effects due to radiation exposure. Present proposals of “absorbed dose (in gray, Gy)” or “RBE•D (Gy)” are not distinguishable from the unit used in the low dose range.
G. Definition of dose limits
The description of dose limit in paragraph 235 as “the dose limit represents a selected boundary in the region between unacceptable and tolerable.” We think the dose limit should not be the boundary rather be in the region of tolerable.
H. Deterministic effect
It is nice to remain the terminology of “deterministic effect” as a compromise by saying it is synonymous to “tissue reaction.”
It is then necessary to take some action to be consistent in the report of “Basis for Dosimetric Quantities Used in Radiological Protection” that is preparing for publication now.
I. Tissue weighting factors
This is not the comment for the present draft but for the future revision of some other publications produced by ICRP.
It is not appropriate to change the parameters used in ICRP so frequently in a short time. Some of the tissue weighting factors have been drastically changing during the process of making new recommendations. That kind of handling may provide bad image to the general public that ICRP does not based on sound scientific results and their handling is very much arbitrary.
J. Typographical errors:
The draft recommendations require a thorough editorial review. Followings are some examples to be amended.
Page 31 (101), line5: R of wR should be a subscript
Page 35 (113), line 7: “thewT” should be spelled separately.
Page 35: Table 4 appears twice on page 35 and page 61 and refers a different table.
Page 37 (131), line 7: The quoted number of the equation is wrong. It should be 4.9.
Page 42 (145), line 4: “man sievert” should be “person sievert.”
Page 50 (184), line 2: “dosethat” should be spelled separately..
Page 78 (318), line 6: “s0ome” should be spelled as “som”.
Page 83 (342), line 3,4: There is no verb for the subject, sometimes prompt actions in this sentence.