|It was my oversight, due to a distraction, that I was not aware of this document until very recently. The need to comment before 24 July 2005 means that my comments can only be relatively superficial and confined to specific sections of the report.
My main interest is in the treatment of genomic instability and bystander effect, what in the report are rightly termed epigenetic effects. Here I have to say I am disappointed with this document. However, I note that more detail is given in another document that I do not have, namely LDR-C-1. This document does not seem to be available on the website.
My comments are made from a public rather than occupational health perspective of the main conclusions of the document.
In the principal conclusions:
I doubt that the DDRF of 2 can now be defended for cancer on the evidence.
The precision to which the detriment adjusted probability coefficients for cancer are quoted are inappropriate given the uncertainty in the evidence.
As far as hereditary disease is concerned it seems unjustified to restrict risk consideration to the first two generations after exposure. Equilibrium may be over restrictive but 2 generations is too lax. Where populations live in contaminated regions, such as around Chernobyl, exposures may occur over several generations. The judgement made here is a social one and the ICRP does not have the legitimacy to make that judgment. Such social judgments cannot be applied “across the board”; different populations may take different views.
I agree that the roles of epigenetic effects are insufficiently understood to be incorporated into a radiological protection framework. However the treatment of the subject in this document is inadequate and I would need to see LDR-C-1 before making any further judgement. In biology in general epigenetic effects are moving up the agenda fast and it would be most unwise, in a document designed to stand the test of time over 15 years, to be as dismissive of their relevance to radiological protection in the future as the this document implies. A particular area of concern is the inheritance of epigenetic effects. It would be wise to signal that this (the changing appreciation of the role of epigenetic effects in general) is an aspect that may well cause reconsideration of radiological protection framework in the future.
I wonder if it is true to say that deterministic effects have true thresholds, or simply thresholds based on detection sensitivity. Rather than say it is a judgment that this is so it would be better to say that “for radiological protection purposes a threshold is assumed”.
The same applies to the in-utero situation. Indeed, I think that recent developments, which I admit are not related to radiation, raise the prospect of epigenetic effects in the affected offspring that are heritable.
I also agree that it is too early to introduce factors for non-cancer disease induction but if it turned out that it was linearly related to dose then its effects would make a significant difference to risk at low doses. It would be as well to acknowledge this.
I have not, due to lack of time, given the document a thorough review and I would need to read also the document LDR-C-1 to get the full picture. Its principal conclusions, however, read as “defensive” of the current framework rather than, as I believe would be more appropriate, as objective, discursive and “detached” from and constructively critical of, what has gone before. Probably it is difficult for this panel to do that as it is to a large degree responsible for what has been adopted in the past. One useful exercise might be to convene a panel to take a forward look (10 to 15 years) at what might be the developments in biology that would influence radiation risk and in what ways and directions. Perhaps the ICRP is not the body to do this but it would an interesting exercise and the fact that the organisation had the confidence either to do it or request that it be done, would increase public and professional confidence in the ICRP and its independence.
K F Baverstock
24 July 2005