Comments on Use of E consultation.
Overall
1. Availability of the quantity E, supported by a workable set of international standards, has hugely simplified the control of different types of radiation exposures from different sources, and has thereby contributed to a high level of radiation safety in the normal course of events. Though not a new observation, this is perhaps the most crucial continuing message of the report. The value to radiation protection in this message can hardly be over-stated.
2. The use of E is not, and was never intended, to supplant the use of other protection quantities in specific exposure conditions where the alternatives are more appropriate. This is another important message that appears to need re-iterating, perhaps more strongly.
3. There are several references to the use of E in risk assessment or in the determination of the scale of health effects as never having being unintended. This contradicts many publication issued by people who were directly involved in the development of the E concept, and could therefore be misleading to stakeholders. If the current intended use of E is different from that originally intended, then the specific differences need to be spelt out very clearly alongside the reasoning for the changes.
4. The above comment is not intended to imply that use of E in risk and/or health effects assessment is always correct, nor that such assessments have always been done in a sensible manner. Much of this is discussed in the current document, with emphasis on medical aspects of radiation protection. However, there would be great benefit from ICRP producing examples illustrating when and how it is appropriate/(or “pragmatic”) to use E in risk or health effect assessment, as regards public and worker exposure alongside medical exposures, and corresponding supporting guidance provided on when collective dose can reasonably be converted to health effects and when it is not so reasonable.
5. In any case, if it is wrong (i.e. was never intended) to convert E into health effects, what has been the point in continuing to recommend nominal risk coefficients, since they don’t apparently apply to individuals either? And if you are not intended to use them, then ICRP needs to offer an alternative approach to demonstrating that the utilitarian as well as the deontological components of the ethical foundations of the system of radiological protection (ICRP 138).
6. Communication of doses and risk needs to address the circumstances. Section 5.4 dose that well for medical exposures, but the document seems to avoid saying equivalent of other exposures, which is a missed opportunity.
7. Of course opinions and methods can develop and change with new information, or for wider social reasons, but it would be good to have a more transparent explanation of those changes, with illustrations showing how various applications of use of E (examples above, but there are a great many more) are still appropriate and reasonable, or no longer are, or never were.
Details
8. L106: Could room be made in the abstract to say what these “questions” are and who raised them and why they are important to consider? (It is well set out in the main text for medical, but perhaps not so well of other exposures.)
9. L116: “Unintended” by whom?
The history of publications provides many examples demonstrating that the E concept was developed in parallel with the need for risk and health effect assessment and then, once developed, applied in a corresponding manner – implying a clear and unambiguous intent to use E as an indicator of risk by some highly relevant organisations and experts. See, for example,
Both contain caveats to the effect that there is more to the decision than CBA or similar technical analyses. In fact this was clearly noted as early as 1970 by Dunster H J and Mclean A. An Approach to the Use of Risk Estimates in Setting and Using Radiation Protection Standards. Proc. Presented at Second International Congress of the International Radiation Protection Association. (1970), vi:
“In recent years, there has been an increasing emphasis on the quantitative assessment of risk following exposure to radiation. {...} It has generally been assumed that this trend will contribute to the formulation of policy and standards in the field of radiation protection. The difficulties of achieving this contribution have, perhaps, been underestimated because the problem has been seen too often as an exercise in science rather than as a combined operation involving, in addition, the skills of management, government and sociology.”
It would thus be good for the current document to more clearly describe the intent behind Dunster, Lindell, Jammet, Pochin and Beninson et als’ development of E for ICRP26, and that they recognised difficulties, as in ICRP27. And then to go on to explain what they did not intend that people apparently have done.
“the then director of the NRPB {Roger Clarke} estimated {in Clarke R H (1989). Current radiation risk estimates and implication for the health consequences of Windscale, TMI and Chernobyl accidents. In Medical Response to Effects of Ionising Radiation. London, Elsevier Applied Science: pp 102–118.} from information available at that time that around 60 thyroid cancers would result from exposure to iodine-131 released during the Windscale accident. These predicted excess thyroid cancers will be distributed geographically according to the areal distribution of the collective thyroid dose (under the conventional assumption of a linear no-threshold dose response), so that although the highest individual thyroid doses will have occurred in Cumbria, followed by Lancashire, only about one-sixth of the collective thyroid dose was received by the population of Cumbria, the remainder being received principally by the population of the rest of England.”
The fact that most of the estimated health effects are said by Carke to come from large numbers of small doses, away from the source, is particularly telling of an intent even to add up small doses over large numbers of people. If such calculations were never intended, is ICRP saying that Clarke made the calculations by accident? If they were right then, but wrong now, what has changed exactly?
“Application of collective dose should be limited to stochastic effects (deterministic effects are not included) and to the dose range in which risk is assumed to be proportional to dose and independent of dose rate…. All doses should be included in calculations of collective dose;
There is no conceptual basis for excluding any individual doses, however small, from the collective dose calculation. There may, however, be practical limitations [see {various}..] ”
This reference provides a more recent and particularly important example of effects estimation based on based on E. It is concluded that no discernible changes in future cancer rates and hereditary diseases are expected and, that no increases in the rates of birth defects are expected that could be attributed to radiation exposure from the accident at Fukushima Daiichi nuclear power station. It was clearly important to have had available a robust basis to make such an assessment and draw the corresponding conclusions.
It was also an important observation that, although no discernible changes in disease rates are expected, it was acknowledged that there is a theoretical basis for possible cancer induction and the situation needs to be followed closely and further assessed in the future. So the current document could be more informative about what have has been learned since 2013.
Of course opinions and methods can develop and change with new information, or for wider social reasons, but it would be good to have a more transparent explanation of those changes, with illustrations showing how various applications of use of E (examples above, but there are a great many more) are still appropriate and reasonable, or not, or never were.
10. L121-124. The caution given is very relevant but could be rephrased to allow that if your best available information based on E level of data, then use it, (RP has to do its job); but if better data are available then you should use that and not, as sometimes happens, adopt the first and simplest approach, and assume it is adequate. Adequacy can be determined in the context of the situation and through consideration of uncertainties. So, and in any case, ICRP could remind/recommend that you should not present results of any such risk analysis without also making clear the assumptions and without discussing the uncertainties.
11. L190. Here is says absorbed dose is, whereas in abstract, absorbed does will be…
12. L227-229. Suggest to add, "However, the currently available dose coefficients in ICRP 119 correspond to the ICRP 60 definition of E, not the ICRP 103 definition." If this is not added, there is a danger that people will use the 119 values under a potentially serious misapprehension that they are using the best available information. ICRP does properly encourage the latter, as explained in Appropriate selection of dose coefficients in radiological assessments: C-14 and Cl-36: response to the letter of G Smith and M Thorne (2015) J. Radiol. Prot. 35 737–40.
13. L232. Implies updates are generally irrelevant to safety- in which case why make the update. (As Geoff Webb said in Hiroshima in 2000, if it ain’t broke, don’t mend it.) It might be better to say that each time there is a major update, then major decisions on safety made on previous recommendations might need to be reviewed. It is more honest to recognise explicitly that best scientific advice (the ICRP role) can change with new information, and that society (if it exists) has to live with it.
14. L236. change site-specific to site and wider circumstances specific.
15. L241. At some stage, this element of conservatism should be at least roughly quantified, e.g. for some key nuclides such as Pu-239 in some key exposure circumstances. This would be really useful. If it has been done, then provide references, ee.g. Puncher et al papers, but they were {arguably} of limited scope.
16. L244-245. Important to add that for long-term dose assessments made in relation to solid radioactive waste disposal, adult is sufficient from a technical point of view, for the demonstration of compliance with RP objectives. (Of course this is said elsewhere by ICRP, but is worth re-stating here since these elsewhere references are not always noticed.)
17. Paras at L254 and 260. These paragraphs are useful advice. Why cannot something similar be said about use of E in assessing (and communicating) risks in prognostic assessment of options for controlling worker and public exposure? Would the advice be different?
18. Para at L281. It should be explained what is the difference between risk projection. and prediction of potential/possible health effects? Clearly, the authors have something in mind, but is not so clear the distinction intended.
For many users of ICRP recommendations, an estimate/prediction/projection of possible future health effects (where possible here covers aspects of probability), is exactly what risk project is. And it can be/is applied with respect to health effects on real or hypothetical or representative individuals and to populations. Some clarification of what ICRP means would be very helpful, e.g. why E was not intended for risk projection, but that it could be ok to “predict potential/possible health effects”. For sure, in common or garden understanding, E was once intended for risk projection, so once again, what changed?
One partial solution might be if the sentence, “It is not intended for use in risk projection.” is deleted. Unaltered the para effectively means, don't use it and when you do be careful. The words in Harrison J D, Balonov M, Martin C J, Ortiz Lopez P, Menzele H-G, Simmonds J R, Smith-Bindman R and Wakeford R 2016 Use of effective dose Ann. ICRP 45 215-24, may be helpful.
19. L300-302. Are these references examples of E’s miss-use, or references showing that it was never intended? Or maybe both…?
20. L499. Consensus among whom… just Preston, ICRP and UNSCEAR? Not IAEA, EC, BEIR, PHE, ASN, FMBA, BfS, SSI, …? (It would be good to demonstrate where the consensus is, but then see next comment too.)
21. L503-504. Add references for this side of the argument too, so it is transparent who is not falling in with the consensus. Maybe consensus is the wrong word, but rather, call it ICRP's and other key organisations’ judgement as opposed to others. But provide the weight of evidence on both sides.
22. L521-522. “These risk coefficients are not intended for use in estimating risks to specific individuals.” This is clear, but the implication is that they are intended to be applied to populations, otherwise they have no use at all.
23. L672- 675. “Publication 103 does present, but does not use, separate risk factors for males and females, averaged over all ages, showing greater nominal risk coefficients and detriment values for females by a few tens of percent.” What is the point in saying does not use above? Makes it look like there is something wrong with them. Should be opposite, i.e. encourage to use when the data are available for their determination.
24. Table 2.5 cases power 100 per Gy)?
25. L1013. Anyone can understand the need not to get over-excited about small changes, or even big changes in things that do not matter. But current text reads too glibly and implies that Webb was right. Surely if you found a big change in something important, you'd need to at least point it out and invite, rather than discourage, review of decisions made. That should not lead to recrimination, but to avoidance of perpetuation of the previous no-longer appropriate decision.
26. Section 3.8 It might be useful to introduce this section with a recognition that ICRP 103 defines "The Principle of Optimisation of Protection: The likelihood of incurring exposure, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking into account economic and societal factors.", suggesting that, in order to adequately address the utilitarian component of the ethical basis to the system of radiation protection (ICRP 138) you need to consider the overall exposure of the exposed group in a given context. This is called collective dose… etc.
27. L1224-1225. It could be added that this is no different from the basis for individual protection, so it is reasonable to think it should work just as well for protection of a group of individuals. E.g. the individual doses (and any inferred detriment) do not disappear when you add them up. (Unless ICRP thinks they doJ)
28. L1228-1232. “Collective effective dose is not intended as a tool for epidemiological risk assessment and it is inappropriate to use it in formal risk projections for such studies. In particular, the computation of cancer deaths based on collective effective doses involving trivial exposures to large populations is not reasonable and should be avoided.”
This reasoning is not adequate. There is a world of difference between epidemiological studies and analysis of optimisation of current or future activities and the two should not be simplistically convoluted. And to say that effective dose and risk coefficients should not be used because the results get quoted out of context is extraordinary. In such a case it is the messenger who wants shooting, not the message.
ICRP should be working to identify and correct those examples instead of throwing away a significant aspect of the system of radiation protection. As indicated above, it is vital for ICRP to show much more clearly where the link between dose and risk is not warranted and where it is. It would be very useful to consider, for example, was the example in Clarke (1989) correct or not, then and now? Study of range of examples could also explore, without necessarily prescribing, what counts as trivial exposures in different circumstances?
Note that, the current wording implicitly makes it clear that when the doses are not trivial, then the computation can and should be done, as part of the optimisation process. ICRP therefore needs to advise on what is likely to be trivial and show how that can be investigated.
It might be noted that, “There are significant challenges in the application of the principle of optimisation, not just within radiation protection itself, but as part of wider judgements on appropriate management of different radiation exposure situations. Without some use of our understanding of the risk associated with a given level of exposure, one cannot balance the risks and benefits of different courses of action that involve multiple hazards. For example, a Gy cannot be readily compared to an intake of a hazardous chemical. Risk estimation for both forms of exposure is necessary to evaluate options proportionately and optimize the application of resources in line with the utilitarian component of {the ethical foundations}…." Smith G M and Martinez N (2017). Ethics, stakeholders and low doses. J. Radiol. Prot. 37, 947–952 (6pp) https://doi.org/10.1088/1361-6498/aa9600
The basis for such commentary is extensive, in IAEA, NEA and other international collaborative work; but just for example, see Sneve et al (2018) Regulatory Supervision of Legacy Sites: The Process from Recognition to Resolution. Report of an international workshop, Lillehammer, 21-23 November 2017. Report of an international workshop organised by the Norwegian Radiation Protection Authority (NRPA) with the official support of the IAEA, ICRP, NEA and IUR, NRPA-2018:4, Østerås.
In the meantime, the parallel words from UNSCEAR are very much clearer than those in the current ICRP document. (Report of UNSCEAR to Fifty-ninth session May 2012. UN General Assembly Official Records. Sixty-seventh session. Supplement No. 46, New York.) viz:
“{Projecting health effects for comparative purposes}, though based upon reasonable but untestable assumptions, could be useful K.. provided that it were applied consistently, the uncertainties in the assessments were taken fully into account, and it were not inferred that the project health effects were other than notional”.
29. Presumably, notional effects mentioned by UNSCEAR are those arising from use of nominal risk coefficients, but it remains unclear what that means in terms of whether, or in what circumstances, we are intended to ignore them or not. ICRP could usefully clarify their position on the meaning of nominal in the context of nominal risk coefficients.
30. L1264-1265. Clear, but:
a. It is vital to recognize that the doses have to be converted to health effects... or some measure of risk to health, so that the radiological risks can be assessed against the other risks associated with an activity and then contribute to optimization in a wider sense.
b. If the balance can be done and is useful for workers, then maybe it can to done for public, e.g. taking account of age and sex distribution if that is not the same as that used to obtain the nominal risk coefficient.? Or if not, then ICRP needs to be clear why/when not, and what to do instead.
31. L136-1347. “… the management of long-term contamination resulting from an emergency situation should also be treated as an existing exposure situation.” ICRP might consider that IAEA GSG11 says different in Arrangements for the Termination of a Nuclear or Radiological Emergency (March, 2018) viz:, “The emergency should be terminated if the relevant prerequisites set forth in this section and selected on the basis of a graded approach (see para. 3.1) have been fulfilled; the decision to terminate the emergency should be a formal decision and should be made public. The new exposure situation should then be managed as either a planned exposure situation or an existing exposure situation (see Fig. 1), as appropriate, in line with the national legal and regulatory framework…”. This appears to leave door open for a different approach, at least so long as an existing exposure situation is never recognised in the first place.
32. L1417, “current requirements” needs clarification: Does it mean the current requirements in the jurisdiction where the exposure occurs (which may be current locally but inconsistent with and/or out of date compared with international recommendations standards and guidance), or current requirements of IAEA, i.e. in accordance with the set or IAEA requirements documents? It might make sense to use the same words as in the final version of IAEA DS468, and avoid scope for inconsistency.
33. L1448-1450. “…consideration of three age groups, 1 year and 10 years old children and adults, is sufficient for most dose assessments, especially for long-term exposures when individual cohort members will naturally proceed through age groups.” Please take account of ICRP advice in 122 and 81 which say that for long-term exposures, adult is enough.
34. L1522-1524. This is very useful guidance. The document might also note that you should not use cautious assumptions in options assessment, as already acknowledged by ICRP in … ICRP 37. It would be very useful to make this clear, for ICRP consistency, but also for consistency with options assessment methods in a wider context..
However, the reduction in dose means nothing unless translated into reduced detriment…
a) so that you can assess the change in radiation {risks} against the change in other (e.g. chemical and physical) risks which will arise concomitantly in many cases,
b) and transparently show the benefits and dis-benefits of alternative uses of resources..
Of course such translation should be subject to all the caveats already mentioned in the report and above.
35. L1522-1524. Suggest adding words to the effect. "Large differences in trivial collective doses arising from two options should not be used to indicate that one option is better than the other." Once again some discussion of the trivial is needed, though again without prescription.
36. L1545. ICRP should explain here the significance of a given difference between two collective doses linked to two options, dis-aggregated in time and space and by individual dose-rate, as appropriate. ASP 4 ref’d above might be a good place to start, updated and corrected, as appropriate.
37. L1549. Is it rotgh to call µSv to nSv very low? UNSCEAR (see comment 34 below) has said very low is less than about 10 mGy so this can’t possibly be right…unless UNSCEAR is entirely wrong. See also Table 5.2 … why would very low be so different for patients and non-patients?
Anyone can understand that patients might accept higher risks, but that would not change the risk (to them) of a given additional exposure. Using different words to describe the same level of dose in different circumstances is not a good way of allowing that the significance of a given dose will depend on the circumstances.
Any communication needs to address the local circumstances. Section 5.4 dose that well for patient exposures, but the document seems to avoid saying equivalent of other exposures, which is a pity.
38. Section 5.4 and table 5.2. Very useful section. but why no equivalent for other public and worker exposure? Big opportunity to be very useful here, e.g. building on Table 5 of ICRP 103 and UNSCEAR and UNEP descriptors for dose levels, as discussed in.Smith G and Thorne M C (2016). Communicating the significance of different levels of dose. Letter in J. Radiol. Prot. 36 (2016) 1004–1007. doi:10.1088/0952-4746/36/4/1004. No implication to agree with recommendations there, but at least address the issues.
39. “In retrospective assessments of planned or existing exposure situations, assessments of 1556 collective effective dose can provide initial screening evaluations of possible health impact to inform medical and epidemiological evaluation.” This conclusion, with the caveats that follow it, should be included in the main points up front. However, this is the first time that the word screening has appeared in the document. It would be helpful to explain briefly what is meant by a screening evaluation.
Thanks for opportunity to comment.