ICRP tries to drop Collective Dose

Control of low-level radiation exposure: time for a change?
Yes! Scrap ICRP

(The account below refers to events in 1999 and the early 2000s. See this link for the outcome)

Roger Clarke, Chairman of ICRP and Director of NRPB, is making a determined attempt to strip the public of all defences against environmental pollution at the levels which the nuclear industry sees as necessary for its operation, the decommissioning of old plant, the recycling of radioactively contaminated materials, and the delicensing of contaminated land.

He has published two papers proposing a new system of regulating low-level radiation doses;

  • The first (1) was intended for discussion among the radiation protection societies of the various nations;
  • the other, published in February, (2) embodies feedback from the International Radiation Protection Association's meeting in Hiroshima in May 2000. In it Clarke declares his intention of driving his project to completion in the shape of new recommendations from ICRP.

ICRP - piggy in the middle

Clarke accepts the existing Linear No Threshold (or "no safe dose") model. He may thus seem to be a moderate, in view of the polarisation between people who believe low level risks are seriously underestimated and the hormesis camp who think small doses actually have a protective function. It is a three-sided debate, in which the third party is ICRP.

Is there a Threshold? No.

But Clarke presents a picture of two sides seeking to resolve the question of whether there is or is not a threshold dose below which radiation cannot cause potentially fatal mutation. He depicts himself as a conservative by roundly dismissing arguments for a threshold.
By ignoring the third protagonist he lets himself off the hook of addressing the wealth of compelling evidence that ICRP's risk factors are serious underestimates.
His oversimplification serves a truly appalling agenda, as we explain here.

Two problems ...

The pro-threshold side of the debate is, Clarke makes clear, motivated by the cost of decommissioning nuclear plant and disposing of contaminated land and materials.
At the same time ICRP has problems of its own, administering a radiation protection system whose complexity disquiets the public and baffles many professionals, especially those in the NORM (Naturally Occurring Radioactive Materials) industries.

Both problems are of man's own making. This is obvious in the case of the pollution. It may be less obvious that the complexity of which Clarke complains is the result of ICRP's modelling of radiation risk -- a theoretical construct in which doses even from hot particles are averaged out across large volumes of body tissue, and based on the idea that natural background radiation is comparable with man-made. Maintaining both these myths is essential to Clarke's enterprise.

He accepts that

... there is uncertainty in risk estimates due to both biology and epidemiology
and that there is a
continuing lack of definitive scientific evidence,

Faced with such ignorance, a scientist would argue for research designed to determine the true biological effects of different radioisotopes and their various chemical and physical forms. It would not be difficult to do research like this and it would put radiation protection on a scientific foundation, but Clarke prefers to alter the perception of hazard to fit ICRP's construct.

It is important to stress that radiological protection systems need to be as simple as possible and to focus on the general consistency of all relevant data, not just the inevitable biological intricacies and exceptions.
Note the sleight of hand:- ... relevant data .. are ... generally consistent ... because they are high, acute, external dose data.
On the other hand, environmental pollution exposes us mostly to long-term internal irradiation from radioactive atoms and particles which we inhale and ingest. The studies on which ICRP bases its risk factors are silent on this kind of exposure; many authorities say that ICRP makes a highly questionable assumption in drawing a straight line from the high dose data to predict risk in the low dose region which Clarke is actually discussing.
Radiobiologists (Clarke is not one) accept that in this low dose region biological intricacies predominate. And exceptions are food and drink to a scientist (is Clarke one?) Exceptions point to the mechanisms which underlie the operation of real world phenomena. Let's not forget that no-one yet knows exactly how radiation causes cancer!

... one crude solution - Let's have a threshold anyway!

Clarke proposes dumping the concept of "Collective Dose". The proposed replacement - "Controllable Dose" - is the idea that so long as the individual most exposed to radioactivity from a particular source were adequately protected, then everybody else would be adequately protected.

"Controllable dose" is reminiscent of a regulatory problem familiar to environmentalists who have long campaigned against pollution limits on the grounds that operators would inevitably tend to pollute up to the limit. In this case people will be polluted up to a limit before any alarm bells ring.

... an arbitrary threshold

"Adequate protection" is defined as what can be demonstrated by such epidemiological studies as the establishment admits, dubious though many of them are. Studies which challenge the conventional view are rigorously ignored, so "Controllable dose" amounts to an arbitrary threshold defined by ICRP's prejudices.

Never mind logic ...

Dropping "Collective Dose" cannot logically be reconciled with the No Threshold assumption. If there is no threshold it follows that releasing radioactivity into the environment is sure to harm somebody, somewhere. You just don't know who, where, or when. This means that a regulator must in all conscience add up the doses to large populations, including those yet unborn.

The extreme example history has so far seen is world-wide exposure to weapons test fallout in the 1950s and '60s; by 1964 it had caused the body of every human being on the planet to contain measurable amounts of Strontium-90. Total collective effective dose to the world population was 30 million man Sieverts (3). Multiplied by the ICRP's most recent risk factors (4) this gives 3.75 million additional cancer deaths, even on ICRP's own figures which incontrovertible evidence shows to be a 100-fold underestimate (5) -
- so the total number of deaths from bomb testing could be 375 million.

... put on blinders ...

If Clarke gets away with dropping "Collective dose" no-one will be counting the impact of future releases.

... and shut the stable door later

Radioactivity in the environment cannot be recalled, so we must consider Clarke's contemptible suggestion that if someone finally notices that letting the horse run amok in the schoolyard has caused a problem, it will be possible to shut the stable door:

If at some time in the future it became possible that some individuals might be liable to receive, in due course and over a prolonged period of time, a significant accumulation of doses from many sources, local, regional and global, then a further restriction of sources may be necessary. There would, however, be likely to be a considerable time period available to effect change.

And to make coffins.

Belt and Braces

To make doubly sure that no-one is counting the human cost of nuclear pollution Clarke explicitly proposes to abandon the principle of Justification. Justification - presently one of the corner stones of radiation protection - requires a cost-benefit analysis of radiation detriment from any particular practice, weighed against the benefits. Clarke's logic for scrapping it is circular: it is that

.. radiological protection essentially plays ... a minor part in a government's decision to justify ... a given use of radiation ...
The existence of the Justification principle has, in theory at least, meant that someone did a radiological cost-benefit calculation at some stage. But not in future, thinks Clarke. The good news is that he's swimming against the tide of public opinion, which is becoming very keenly aware of radiological protection issues.

How much poison will you take?

It is as if we were being asked what dose of poison would be acceptable to the public. There are many poisons with different modes of acting, toxic at widely differing concentrations; so we wouldn't give an answer to such a silly question without asking first What kind of poison? ; and then How do you know the relationship between dose and effect for whatever poisons you're intending to hit us with?
By analogy, Clarke's answer to the first question is: Any kind of poison - they're all essentially the same.
His answer to the second would have to be We don't know, at low doses we're just guessing.

Chalk is Cheese

Clarke's mentor seems to be Dwight D. Eisenhower, whose dictum on the health effects of nuclear bomb testing was Keep the public confused; we are to be persuaded to think of man-made radioactivity in terms of Natural Background:-

... it must be remembered that ... exposures are always increments on the natural background radiation ....
-- just as cheese is always an increment on chalk.

This is the lie, which if it can be implanted deep enough, will make life easy for ICRP:-

... if the public could be made to understand radiation risk in terms of multiples or fractions of natural background there might be "no need to destroy the credibility of the [radiation protection] profession in arguments for or against a threshold.
This is not science, it's Public Relations. What is the use of a profession that builds its standards on half truths and neglect of basic research?

Clarke asks ... Time for a change?. The answer has to be Yes; ICRP must be replaced with real science.

The end of the story
In the end ICRP dropped the idea.
The sheer cynicism of Clarke's proposals inspired this allegorical treatment:-
Roger, the King of Radsavia! - a fairy story for grown-ups


1 R. H. Clarke: "Control of low-level radiation exposure: time for a change?" Journal of Radiological Protection, 1999, 19 No. 2

2 R. H. Clarke: "Progress towards new recommendations from the International Commission on Radiological Protection", Nuclear Energy 2001, 40, No. 1 Feb. 37-45

3 UNSCEAR 1993 Table 11

4 i.e. 0.125 fatal cancers /Sv.

5 Busby, C. Scott Cato, M. 2000 Increases in Leukemia in Infants in Wales and Scotland Following Chernobyl: Evidence for Errors in Statutory Risk Estimates. Energy and Environment Vol. 11 2000, No. 2 127-139

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