|Thank you for the opportunity to provide comment on the ICRP draft recommendations. Overall the draft has been considerably improved by the changes made in response to consultation and is in general supported. There are however a number of areas where further improvement in consistency and clarity could be achieved, as outlined in the comments below.
There are several formulations of the ALARA principle throughout the document that are not consistent. For example, in para. (30) the description under optimisation is different from that used in para. (193), which includes reference to being below dose constraints. Also is the change from social to societal intended? In some cases social is still used (e.g. in para. (227)). Given the importance of optimisation in the radiological protection system, it would be helpful to use consistent wording throughout the document when discussing ALARA.
2.3 Scope of the recommendations
The use of planned, emergency and existing situations to replace practice and intervention is supported. However, the wording of para. (39) could perhaps be improved to make its intention clearer. The first sentence is somewhat circular, and in the second sentence “the only options” may not be appropriate.
2.4 Exclusion and exemption
ARPANSA generally supports this section, particularly the approach in para. (43), that regulatory control should not be applied if it is unfeasible or the societal efforts needed for its application would be disproportionate to the saving in detriment. However, this seems to be at odds with the statement in para. (42), that one of the concepts defining the extent of radiological protection control is “… the exemption from radiological protection regulatory requirements of situations that are unwarranted to be controlled because the associated risk is negligible under any conceivable circumstance.” This inconsistency should be clarified.
3.2.1 Risk of cancer
ARPANSA strongly supports the position of the Commission as stated in para. (55) to the effect that ‘the weight of evidence on fundamental cellular processes coupled with dose-response data supports the view that in the low dose range under 100 mSv it is scientifically reasonable to assume that the increase in the incidence of cancer or hereditary effects will rise in direct proportion to an increase in the absorbed dose in the relevant organs and tissues’. The evidence in support of this position has been well reviewed and assessed in ICRP Publication 99 and the BEIR VII report.
ARPANSA also supports the view expressed in para. (57) about the calculation of hypothetical cases of cancer from very small doses to large numbers of people over a long period of time. In addition to the uncertainty, there is simply a question of how meaningful an very low additional probability of incidence of cancer is to an individual, let alone to the aggregation of such very low probabilities.
4.3.4 Effective dose and tissue weighting factors
The intended treatment of remainder tissues in para. (114) and Table 4 should be clarified further by making the wording more explicit about how the weighting factor is to be applied to the 14 remainder tissues.
5.4.3 Members of the public
ARPANSA supports the use of a representative individual to replace the concept of critical group. It is noted, however, that in other parts of the document (eg para. (198)) the term ‘the most highly exposed individual’ is used.
5.7.1 Justification in situations involving occupational and public exposure
The last sentence of para. (188) is not helpful. It should either be re-worded to make it clear what is important about justification judgements on particular types of practices, or it should be deleted.
5.7.2 Justification for medical exposure of patients
In para. (191) three levels of justification are described, however this is not consistent with paras. (247) – (250), which state that there are two levels of justification of a procedure in medicine. This needs to be made consistent.
5.8 Optimisation of protection
See earlier comments regarding ALARA in relation to para. (193).
Para. (196) provides a list of dot points on the elements of the optimisation process. However the extent and rigour with which these are applied may be limited in simple operations (e.g. dentistry). Some form of ‘graded approach’ may be usefully discussed here.
5.8.4 Dose constraints for occupational exposure
The first dash point in para. (213) is very complex and should be rewritten to make the meaning clearer.
5.8.5 Dose constraints in medical exposure of patients
The heading of this section indicates that it is about exposure of patients, however other than the first 2 lines, the remainder of para. (215) is not about exposure of patients. It is suggested that either “of patients” be deleted from the heading or the material about carers and relatives be moved elsewhere.
6.4.2 Medico-legal exposures
The point of this paragraph is not clear. Is it trying to say that constraints of a few mSv should be applied, which is different from other exposure as a patient where constraints are not used? Is it trying to say that higher dose procedures such as CT are not likely to be justified in medico-legal exposures? Some re-wording of this paragraph would be helpful.
7.2 Industries involving exposures to naturally occurring radioactive material
The approach adopted in this section is noted and agreed.
9.1 Types of emergency situations
In para. (339), the last sentence indicates that intervention levels from earlier publications are now regarded as constraints. However, in para. (348), the first sentence says that results of optimisation below the dose constraint will lead to intervention levels. This appears to be circular and requires clarification.
11.2.1 Occupational services for protection and health
While it is noted that this chapter is illustrative rather than exhaustive, paras. (385) – (388) appear to be written from the perspective of a large organisation dealing with significant radiation exposures. The wording implies that such a medical infrastructure is necessary for all radiation users, even small businesses such as dentists and veterinary surgeons. Some explanation of when such a range of services may be required, or where it may be unnecessary would be helpful.
A number of other minor typographical errors were also noted as follows:
Preface: delete hyphen before last sentence of first paragraph.
Para (1): delete “the” from last line.
Para (6): change “on the average” to “on average” on third last and second last lines.
Para (11) & Para (15): spaces between the dot points are not used consistently.
Para (17): change “computed averaging” to “computed by averaging” on line 3.
Para (28): change “from” to “to” on line 6.
Para (57): change “ambiguously” to “unambiguously”.
Para (135): change “se” to “see” on last line.
Para (148): equation number is in wrong font.
Para (188): change “they produce” to “it produces” on line 7 and “caused” to “it may cause” on line 8.
Para (255): insert “levels” after “reference” on line 1.
Para (286): insert “variable” at end of third sentence.
Para (303): delete comma at end of paragraph.
Para (314): delete extra full stop at end of paragraph.
Para (315): change “s0ome” to “some” on line 6.