La mortalité va exploser. Les pollueurs doivent payer.
Recommandations du Comité Européen pour les Risques des Radiations (CERR) : les effets sanitaires des expositions à de faibles doses de rayonnements ionisants, à des fins de radioprotection.
 |
Espanol |  |
Française |  |
Japanese |  |
English |  |
Russian |
Le ECCR a appliqué les nouveaux facteurs de pondération Wj et Wk, aux données de l’IUNSCEAR pour la dose collective due à des retombées radioactives, y compris des essais nucléaires, jusqu’en 1989. L’impact total sur la santé humaine est calculée et comparée avec les données de la CIPR :
– Total des morts par cancers : 61 619 512, (CIPR : 1 173 606),
– Total des cancers : 123 239 024 ,(CIPR : 2 350 000),
– Mortalité infantile : 1 600 000, (non prise en compte par la CIPR),
– Mort foetale : 1 880 000, (non prise en compte par la CIPR),
– Perte de la qualité de vie : 10%, (non prise en compte par la CIPR).
Le Comité reconnaît le problème éthique posé par l’exposition de populations à des substances mutagènes sans qu’elles le sachent et sans qu’elles y consentent,et quand un grand nombre des personnes exposées (beaucoup d’entre elles n’étant pas encore nées), n’en tirent aucun bénéfice pour contrebalancer les atteintes à leur santé. C’est pourquoi le Comité s’est entouré de moralistes, juristes, environnementalistes et d’universitaires, spécialistes des attitudes sociales face au risque et à la construction de la connaissance.
Les Recommandations présentent une critique de l’approche éthique, essentiellement utilitaire, de la CIPR, et une alternative dérivée des théories de Rawls basée sur les droits.
Voir www.euradcom.org pour “renseignements sur le Comité”, la “Base et le Sujet du Rapport”, et le “Sommaire” .
26th April 2011: On the 25th Anniversary of the Chernobyl Catastrophe,
mindful of the continuing discord over the extent of its impact on health,
and mindful of the implications of that discord for public safety in regions affected by radioactivity from Fukushima,
the Committee has published an appraisal of the global health consequences of the Chernobyl accident.
ECRR
2010 Recommendations
of the European Committee
on Radiation Risk
The Health Effects of Exposure to Low Doses of Ionizing Radiation
Regulators’ Edition: Brussels 2010
2010 Recommendations of the ECRR
The Health Effects of Exposure to Low Doses of Ionizing Radiation
Regulators’ Edition
Edited by Chris Busby
with
Rosalie Bertell, Inge Schmitz-Feuerhake,
Molly Scott Cato and Alexey Yablokov
Published on behalf of the European Committee on Radiation Risk
Comité Européen sur le Risque de l’Irradiation
Green Audit 2010
European Committee on Radiation Risk
Comité Européen sur le Risque de l’Irradiation
Secretary: Grattan Healy
Scientific Secretary: C.C.Busby
Website: www.euradcom.org
2010 Recommendations of the ECRR
The Health Effects of Exposure to Low Doses of Ionising Radiation
Edited by:
Chris Busby, with Rosalie Bertell, Inge Schmitz Feuerhake Molly Scott Cato and Alexey Yablokov
Published for the ECRR by:
Green Audit Press, Castle Cottage, Aberystwyth, SY23 1DZ, United Kingdom
Copyright 2010: The European Committee on Radiation Risk
The European Committee on Radiation Risk encourages the publication of translations of this report. Permission for such translations and their publication will normally be given free of charge. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise or republished in any form, without permission in writing from the copyright owner.
The ECRR acknowledges support from:
The International Foundation for Research on Radiation Risk,
Stockholm, Sweden ( www.ifrrr.org)
ISBN: 978-1-897761-16-8
A catalogue for this book is available from the British Library
Printed in Wales by Cambrian Printers
(Cover picture: XY projection of secondary photoelectron tracks induced in a 20nm diameter Uranium nanoparticle by 1000 natural background radiation photons of energy 100keV;in a water particle of the same size this exposure would produce 0.04 tracks in the same XY plane. FLUKA Monte Carlo code. Elsaessar et al. 2009)
The ECRR acknowledges the assistance of the following individuals, including contributors to its 2009 Lesvos Greece International conference where the development of its 2010 recommendations was discussed:
Prof. Elena Burlakova, Russian Federation
Dr Sebastian Pflugbeil, Germany
Prof. Shoji Sawada, Japan
Dr Cecilia Busby, UK
Prof. Mikhail Malko, Belarus
Prof. Angelina Nyagu, Ukraine
Prof. Alexey Nesterenko, Belarus
Dr Alfred Koerblein, Germany
Prof. Roza Goncharova, Belarus
Dr VT Padmanabhan, India
Dr Joe Mangano, USA
Prof. Carmel Mothershill, Ireland/Canada
Prof. Daniil Gluzman, Ukraine
Prof. Hagen Scherb, Germany
Prof. Yuri Bandashevsky, Belarus
Dr Alecsandra Fucic, Croatia
Prof. Michel Fernex, France/Switzerland
Prof. Inge Schmitz Feuerhake, Germany
Prof. Alexey V Yablokov, Russian Federation
Prof. Vyvyan Howard, UK
Mr Andreas Elsaesser, UK
Prof. Chris Busby, UK
Mm Mireille de Messieres, UK/France
Mr Grattan Healy, Ireland
The agenda Committee of the ECRR comprises:
Prof. Inge Schmizt Feuerhake (Chair), Prof. Alexey V Yablokov, Dr Sebastian Pfugbeil, Prof. Chris Busby (Scientific Secretary) Mr Grattan Healy (Secretary)
Contact: scisec@euradcom.org
Contents
Preface
1. The ECRR. 1
2. Basis and scope of this report 6
3. Scientific principles 9
4. Radiation risk and ethical principles 19
5. The risk assessment black box: ICRP 36
6. Units and definitions: extension of the ICRP system 44
7. Establishing the health effects at low dose: risk 63
8. Establishing the health effects at low dose: epidemiology 75
9. Establishing the health effects at low dose: mechanisms 84
10. Risks of cancer following exposure. Part I: early evidence 107
11. Risks of cancer following exposure. Part II: recent evidence 121
12. Uranium 144
13. Non-cancer risks 163
14. Examples of application 173
15. Summary of risk assessment, principles and recommendations 180
16. List of ECRR members and other contributors to this report 183
All References 189
Executive Summary 239
Annex A: Dose coefficients 244
Appendix: The Lesvos Declaration 246 ECRR 2010
ECRR 2003 was dedicated to Prof. Alice M Stewart, the first scientist to demonstrate the exquisite sensitivity of the human organism to ionizing radiation. The Committee dedicates this present volume to the memory of:
Prof. Edward P Radford,
Physician and Epidemiologist
“There is no safe dose of radiation”
Radford was appointed Chair of the BEIR III committee of the US National Academy of Sciences. His BEIR report in 1979 drew attention to the inadequacies of the then-current radiation risk model. It was withdrawn and suppressed but he resigned and published a dissenting report. His career was destroyed.
In 2009 the ECRR awarded the Ed Radford Memorial Prize, donated by his widow Jennifer and the Radford family in the USA to
Prof. Yuri I Bandashevsky
Physician and Epidemiologist
Bandashevsky drew attention, through his scientific research and self publications in English, to the effects of internal radioactivity from Chernobyl on the health of the children of Belarus and was rewarded by arrest and imprisonment.
1 ECRR 2010 2
Preface
The presentation in 2003 of the new radiation exposure model of the European Committee on Radiation Risk caused something of a revolution in the focus of scientists and politicians on the adequacy of previous scientific theories of the effects of radiation on living systems. This was long overdue, of course, since evidence has been available for more than 40 years that it was unsafe to use studies of external acute radiation to inform about risk from internal chronic exposures to evolutionarily novel radionuclides. Such a scientific paradigm shift is not easy: the course and direction of the nuclear, military, economic and political machine dedicated to the development of nuclear energy and its military applications is monolithic and has massive inertia. It was therefore surprising and encouraging that ECRR2003 received such attention, and effectively brought about a new and intense interest in the flaw in the then-current philosophy of radiation risk: the physics-based concept of absorbed dose. The support and encouragement for the new model, and its success in many court cases (where it was invariably set against the ICRP model) was perhaps assisted by the increasing evidence from Chernobyl fallout exposures and from examination of Depleted Uranium effects which were emerging at the time of ECRR2003. The success of the ECRR model is that it gives the correct answer to the question about the numbers of cancers or other illnesses that follow an exposure to internal fission products. This is immediately clear to anyone: to juries and judges as well as ordinary members of the public. It received powerful support from reports of increases in cancer in Belarus after Chernobyl and also from the epidemiological studies of Martin Tondel of cancer in northern Sweden published in 2004: Tondel’s findings of a statistically significant 11% increase in cancer per 100kBq/m2 of Cs-137 contamination from Chernobyl are almost exactly predicted by the ECRR2003 model.
There have also been developments in laboratory science that can be explained in the new model but are quite impossible to explain in the old ICRP model. One of these is the understanding that elements of high atomic number, like Uranium (but also non-radioactive elements like Platinum, Gold etc.) have the ability to alter the absorption characteristics of tissues in which they are embedded. Uranium is the central element around which the nuclear fuel cycle revolves, and huge quantities of the substance have been contaminating the biosphere since early in the last century. It is therefore necessary to update the ECRR risk model and include consideration of these ‘phantom radiation effects’. The widespread dispersion of Uranium from weapons usage has made it necessary to add a chapter on Uranium weapons. Since its founding in Brussels in 1998, the ECRR has been joined by many eminent radiation scientists from many countries. It will be clear from this new revised edition that the pressure on politicians and scientists to change their understanding of the health effects of ionizing radiation is now too great to ignore. ECRR 2010
1
The ECRR
1.1 The background
The European Committee on Radiation Risk is a spontaneous creation of Civil Society which was faced with clear and alarming evidence of the failure of its democratic institutions to protect it from the effects of radioactive pollution. Predictably, the engine which generated this development was the Green movement, the result of another and earlier Civil Society reassessment of the aims and ideologies behind the systematic exploitation and contamination of the planet. The ECRR was formed in 1997 following a resolution made at a conference in Brussels arranged by the Green Group in the European Parliament. The meeting was called specifically to discuss the details of the Directive Euratom 96/29, now known as the Basic Safety Standards Directive. This Directive has, since May 2000, been EU Law regulating exposure to radiation and to releases to the environment of radioactivity in most countries of the Union. The Euratom Treaty preceded the Treaty of Rome and so once the document had been passed by the Council of Ministers there was no legal requirement for the European Parliament to address it. It was thus cleared without significant amendment although, astonishingly, it contained a statutory framework for the recycling of radioactive waste into consumer goods so long as the concentrations of itemised radionuclides were below certain levels.
The Greens, who had attempted to amend the draft with only limited success, were concerned about the lack of democratic control over such a seemingly important issue and wished for some scientific advice regarding the health effects which might follow the recycling of man-made radioactivity. The feeling of the meeting was that there was considerable disagreement over the health effects of low-level radiation and that this issue should be explored on a formal level. To this end the meeting decided to set up a new body which they named the European Committee on Radiation Risk (ECRR). The remit of this group was to investigate and ultimately report on the issue in a way that considered all the available scientific evidence. In particular, the Committee’s remit was to make no assumptions whatever about preceding science and to remain independent from the previous risk assessment committees such as the International Commission on Radiological Protection (ICRP), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the European Commission and risk agencies in any EU member State.
The ECRR’s remit was and is:
To independently estimate, based on its own evaluation of all scientific sources, in as much detail as necessary, using the most appropriate scientific framework, all of the risks arising from exposure to radiation, taking a precautionary approach.
1 ECRR 2010
To develop its best scientific predictive model of detriment following exposure to radiation, presenting observations which appear to support or challenge this model, and highlighting areas of research which are needed to further complete the picture.
To develop an ethical analysis and philosophical framework to form the basis of its policy recommendations, related to the state of scientific knowledge, lived experience and the Precautionary Principle.
To present the risks and the detriment model, with the supporting analysis, in a manner to enable and assist transparent policy decisions to be made on radiation protection of the public and the wider environment.
Shortly after the ECRR was formalised, the Scientific Options Assessment (STOA) Unit of the European Parliament arranged (on the 5th Feb. 1998) a meeting in Brussels to consider criticisms of the ‘Basic Safety Standards’ for the public and workers from exposure to ionising radiation. At this meeting the eminent Canadian scientist Dr. Bertell argued that the ICRP, for historical reasons to do with the development of nuclear weapons and nuclear power during the Cold War period, were biased in favour of the nuclear industry and that their conclusions and advice in the area of low-level radiation and health were insecure.
Unfortunately, the STOA rapporteur, the late Prof. Assimakopoulos, did not accurately report the presentation of Dr Bertell, which was wide-ranging and extremely critical of the ICRP and its advice (Asssimakopoulos 1998). Responding for the ICRP, Dr.Valentin, its scientific secretary, told the workshop that the ICRP was an independent body which gave advice on radiation safety, but that those who considered this advice unsafe or questionable were entirely free to consult any other group or organisation. Members of the European Parliament who attended this meeting took note of this suggestion and agreed to support the preparation of a new report by the ECRR which would address the issue of the health effects of radiation exposure and could provide an alternative analysis to the one which underpins present legislation.
It was a widely held view, both at the initial meeting of the ECRR and at the STOA meeting, that enough evidence was available then showing that low-level exposure to man-made radioactive material caused ill health, and that the conventional models of the ICRP and other agencies, which used the same radiation risk models, entirely failed to predict these effects. A fresh approach to the problem was thus necessary, and in 2001 various members of the European Parliament together with two charitable Trusts supported the drafting of the 2003 report.
1.2 Developments since 2003
The presentation in Berlin in 2003 of the first ECRR recommendations (ECRR2003: the 2003 Recommendations of the European Committee on
2 ECRR 2010
Radiation Risk. The health effects of radiation exposure at low doses for radiation protection purposes) represented a watershed in the perception of the hazards of exposures to ionizing radiation. The ECRR published the new pragmatic risk model for calculating the effects of exposure to ionizing radiation. The application of this model, which was based on epidemiological data and scientific reasoning using historic absorbed dose data and known physico-chemical behaviour of elements, gave results which explained and predicted observations of exposed populations. It received significant attention. The report was reprinted three times and has been translated into Japanese, Russian, French and Spanish. A Czech edition is being prepared. It was addressed by the UK National Radiological Protection Board (NRPB), which dismissed it. At the same time the UK Environment Minister Michael Meacher founded an official government committee CERRIE to discuss the implications of the arguments and the evidence which supported them (CERRIE 2004, 2004a). These arguments were also addressed over the two years following the publication of ECRR2003 by the French IRSN which put a team of scientists to review the model. The resulting IRSN report (IRSN2005) concluded that the concerns of the ECRR regarding the scientific basis of the current ICRP model (and all similar models) were well-founded, although IRSN took issue with the scientific basis of the model itself. It was unlikely that ECRR’s arguments would be accepted universally: this was and is a political issue, a matter which is discussed briefly in the present report.
In the period since 2003 and the CERRIE Committee, the radiation-risk landscape has altered totally. When the ECRR began, questions about internal exposures and their anisotropy of effect at the cellular target, the DNA, were largely new, or at least had been avoided by the ICRP. The epidemiological basis of the risk model at the time was solidly that of external exposures at high doses: the Japanese A-Bomb survivors study and its interpretation in ICRP1990. Since then, the health effects of the Chernobyl accident have become all too apparent, although these data seem to have been ignored by ICRP and the UNSCEAR which have shrilly continued to categorize such alarming reports as ‘radiophobia’. Nevertheless, radiophobia cannot affect generations of bank voles, wheat plants, and other life forms whose genetic developments were described by eminent research scientists contributing to ECRR2006 and ECRR2009.
The results of real data on Chernobyl affected territories (both in the ex-Soviet Union countries and in European countries) bore out the predictions of the ECRR2003 model. Since then there have also been reports of anomalous effects of exposure to the element Uranium, in molecular and in particulate forms, as it exists in the fallout from the use of Uranium weapons, so-called Depleted Uranium. This has led to significant effort into research on the effects of internal exposures to Uranium. The questions raised by this research are also those posed by ECRR in 1997 and which have formed the basis of the ECRR2003 model, the development of weighting factors for internal exposures
3 ECRR 2010
to certain isotopes based on their chemical affinity for DNA and their mode of decay.
In 2004, Dr Okeanov of the Belarus cancer registry visited Switzerland and presented data on increased incidence rates which were in line with those predicted by ECRR2003. Also in 2004, a study of cancer in northern Sweden showed that there was a statistically significant 11% increase per 100kBq m-2 Caesium-137 contamination the 5 years following the Chernobyl fallout (Tondel et al 2004). This can be shown to demonstrate a 600-fold error in the ICRP model, and supports the evidence given in ECRR2003 that the weapons test fallout had a similar effect with a similar error factor. The data from Belarus and the findings in Sweden 2004 could therefore be seen as a confirmation of the new model.
In 2007, the latest of a long series of childhood leukemia studies was published: this one from the German Childhood Cancer Registry, showing a statistically significant effect on child cancer in those living within 5km of nuclear plants (KiKK 2007). The size of this study, and the affiliation of the authors, made it impossible to conclude that this was anything but proof of a causal relationship between childhood cancer and nuclear plant exposures to radioactive releases. This study thus added to those highlighted in ECRR2003 which collectively put the error in the ICRP model as about 500 to 1000-fold.
In 2009, in an update of the study reported in ECRR2003, a meta-analysis of data on the epidemiology of infant leukemia after Chernobyl, showed a statistically significant 43% excess in those children who were in utero at the time of the Chernobyl fallout: the error that this highlighted in comparing external and internal exposures was a 600-fold error (Busby 2009)
None of these issues were incorporated into the 2007 ICRP report which ignored all the evidence and cited a selection of research papers which supported its own model. The ICRP took its evidence from UNSCEAR 2006 which in turn failed to cite any evidence that showed that the ICRP risk model was falsified by data.
Further, it has been increasingly clear that the internal exposures to fission product fallout and to Uranium from atmospheric weapons tests has been the principle cause of the current cancer epidemic, a matter which was presented in ECRR2003. Legal cases and test veteran tribunals are now routinely won on the basis of ECRR2003 and its arguments (e.g. Dyson 2009) Government agencies increasingly employ the model to scope the outcomes of new practice, placing the outdated ICRP model at one extreme and the ECRR model at the other.
The embarrassment of the ICRP came to a head with the matter of Uranium photoelectron enhancement, a new development which is discussed in the present report. This idea, which considers the absorbing medium and its atomic variability, rather than assuming uniform tissue-equivalent material, shows Uranium to be hundreds of times more dangerous that is currently modelled by ICRP due to its high atomic number. ICRP and other satellite
4 ECRR 2010
agencies have been unable to respond credibly to this development yet nothing has changed and Uranium exposures continue to be sanctioned. Over the period many studies of epigenetic effects, such as bystander signalling and genomic instability have continued to falsify the scientific basis of the ICRP model, the clonal expansion theory of cancer. The model is now bankrupt.
In early 2009, the Scientific Secretary of ICRP, and editor of both its 1990 and 2007 reports, Dr Jack Valentin, resigned. At an open discussion in Stockholm between him and Prof Chris Busby of ECRR on April 21st 2009 he stated that the ICRP risk model could not be employed to predict or explain the health effects of exposures to human populations. This was, he continued, because the uncertainties for internal exposures were too great, a matter in some cases of two orders of magnitude. This has been the contention of ECRR since its formation, and is written down in ECRR2003. Valentin also stated (in this video interview) that since he was no longer employed by ICRP he could say that he thought it was wrong for ICRP and UNSCEAR to ignore the Chernobyl and other effects raised by the literature reports and by ECRR..
In May 2009, ECRR held an international conference in Greece, Lesvos Island, attended by physicians and radiation specialists from eight countries. At this conference, the ECRR2003 risk model and its development were intensively discussed, including new evidence which has emerged since 2003, as well as incorporation of the phenomenon of photoelectron enhancement by elements of high atomic number and with a discussion of the effects of Uranium exposure. A concluding statement, the Lesvos Declaration, was formulated (see Appendix). The statement called for the urgent abandonment of the ICRP risk model by governments and, as an interim measure, the adoption of the ECRR2003 model. This model is updated here in 2010 with addition of new evidence which has emerged since 2003, and the incorporation of the phenomenon of photoelectron enhancement by elements of high atomic number, and with a discussion of the effects of Uranium exposure.
Since it is clear to the Committee that political and lobbying opposition to the adoption of new rules which have massive political, economic, military and legal implications is likely to be (and has been) significant, the area of the science-policy interface requires discussion. New approaches must be developed with a view to obtaining secure policy from scientific advice. Such a discussion has been added to Chapter 3. This is extremely relevant to the event which founded the ECRR. Although the Greens were unable to significantly affect the Basic Safety Standards Directive 96/29, they were able to amend it so that Article 6.2 required that:
Member States must review Justifications of all classes of practice
involving exposures if new and important evidence emerges.
Such is now clearly the case on both epidemiological and theoretical grounds.
5 ECRR 2010
2
Basis and Scope of the 2010 Report
2.1 Objectivity
For reasons based on the principles outlined in the previous chapter, the Committee takes the view that its analysis should be based on all available information. The Committee believes that in the search for scientific objectivity it should ‘look out of the window’, rather than following the trend of increasing dependence on desktop mathematical modelling. Thus the Committee has considered the results of studies published in the peer-review literature and also reports, books and articles which have not been submitted for peer review. The Committee believes that the approach adopted by scientific risk committees of only accommodating evidence with accurate dose-response data published in peer-review scientific journals has resulted in the propagation of a model which is increasingly seen to be unsafe (Carson 1962, Bertell 1986, Nussbaum and Koehnlein 1994, Busby 1995, 2006, 2009, Sawada 2007). Furthermore, the Committee believes that discussions in the area of radiation risk must involve all groups in society. Therefore, although primarily consisting of scientists, the Committee and its advisors include those physicians and specialists who must deal with medical problems of exposed persons. For example, risk assessment should include physicians trained in public health, occupational health, oncology, pediatrics, and scientists trained in genetics, epidemiology and biochemistry. These disciplines are not represented in the Main Committee of the ICRP. The regulations on membership as posted by ICRP includes: physicists, medical regulators, radiologists, biophysicists, etc. Among those included as advisors to the ECRR are specialists such as ecologists, zoologists, botanists, risk sociologists, lawyers, politicians and members of non-governmental organizations and pressure groups.
2.2 Basis of the report
The present report, like the 2003 report, is intended to be accessible to and to inform decision makers who need to assess health risks to workers and members of the public who may be exposed as a result of practices which involve ionising radiation. The basis of the report is a perceived failure of the present radiation-risk model (referred to in this report as the ICRP model) to explain or predict real increases in ill health in a large number of groups exposed to ionising radiation at low doses and low dose rates. Most of the examples where this has occurred will be referred to in the body of the report but the position of the Committee has also been affected by much that cannot be included, for reasons of space.
This includes reports which have been published in the peer-review literature, and reports which have not, or which started life as television documentaries and ended as court cases. It includes consideration of those who
6 ECRR 2010
voted with their feet and left areas where there were nuclear sites, regions which slowly became wastelands where only the poorest people would live and where the beaches were deserted by holidaymakers and fish were increasingly difficult either to catch or sell. It includes the stories of ordinary people who have been affected by man-made radioactivity, in India, Namibia, Kazakhstan, Nevada, Australia, Belarus and the Pacific Islands. It includes the massive literature, both peer-reviewed and so-called grey literature, that surrounds the phenomena of exposure to Uranium weapons, from the Atomic Bomb test veterans to the populations of Iraq and the Balkans and veterans of those Uranium wars.
2.3 Scope of the report
The report will critically review the present methodology for assessing radiation risk. It will argue that its dependence on averaging, in the area of energy deposition in tissue in space as well as in time, and also its dependence on epidemiological studies involving external exposure, has resulted in major errors in its quantification of risk from internal irradiation. It is intended that the report should convey sufficient evidence that the present radiological safety models are largely accurate for external irradiation situations involving doses greater than 100 mSv so long as the exposures are well defined and uniform, but break down where calculations involving averaging methods are used to examine non-uniform doses in microscopic tissue volumes. It is the microscopic distribution of ionizing events in tissue, from the point of view both of the external field and of the medium of absorption, which is the critical factor in radiobiological damage and this has not been modelled by the physics-based ICRP model which largely ignores molecular interactions, dealing rather with average energy transfer.
The report will examine the historical origin of the ICRP model and will review epidemiological evidence for its successes and failures. The report will consider the philosophical and methodological aspects of the science of radiation risk and make a distinction between the inductive and deductive approaches to establishing objective risk estimates. It will discuss the current science-policy interface and the opportunity for (and evidence of) bias in the translation of scientific (experimental) knowledge into changes in policy. It will present evidence for quantitative ranges of error in the ICRP models as highlighted by various authors and studies and will assemble these into a set of hazard enhancement weighting factors which form the basis of a pragmatic approach to the problem of assessing radiation risk using the present units and quantities. It will extend radiological protection to non-cancer illnesses, lens destruction, neurological illnesses, diabetes, immunologies and several other radiogenic illnesses and will now specifically include a risk factor for heart disease.
7 ECRR 2010
Finally, the report will briefly outline some examples of the application of such a system for assessing radiation risk. A calculation of the mortality yield of the post-war nuclear age based upon ICRP and modified ICRP risk factors will also be presented. The approach is necessarily pragmatic. Data on radiation exposures and activities has historically been tabulated and recorded using units of absorbed dose devised from within the ICRP system: it is therefore necessary to provide factors which may be used with this system and this is what the Committee has striven to achieve. These factors are provided as central estimates of hazard-enhancement for certain types of exposure and may be used as multipliers of risk for the risk factors presently used by ICRP. However, the Committee believes that the use of the average energy dose units Gray and Sievert places too many constraints on the science of risk assessment for internal isotopes and that a different, more rational system of assessing such exposures is required. Some suggestions were made towards achieving such a system were made at the 2009 ECRR conference in Lesvos, Greece, but the consensus was that major difficulties existed in developing such a system and that the bases of such a system were best employed in developing semi-empirical weighting factors for the current system of absorbed doses.
2.4 References
In ECRR2003 the Committee carefully considered the question of whether the editors should attempt to reference every statement made in this Regulators’ Edition. On the one hand, the ICRP, whose handbook ICRP90 the ECRR2003 volume was intended to supplant, provided no references. On the other hand, the more lengthy reviews of the United Nations (UNSCEAR) and the US Academy of Sciences (BEIR) carry selected references which support their statements whilst failing to cite work which either falsified or did not support their statements. The new 2007 ICRP Publication 103 contains 286 references. However, as the analysis in Chapter 5 shows, 90 of these are to non-peer-reviewed reports by ICRP itself, whilst only 120 are in peer-reviewed journals and these are reports mostly written by individuals associated with the risk organizations themselves. There are no references to any effects of Chernobyl or to childhood leukemia clusters near nuclear sites or to Uranium effects.
In ECRR 2003 the Committee considered the constraints that would be placed on the size of the edition if all statements were fully referenced, and the loss of flow of the argument which would follow the considerable expansion of the text. As a compromise, it decided to attach a list of the main works on which its beliefs are founded, without attaching each to some piece of the text. There was some criticism of the 2003 report on the matter of references and so in this 2010 report many references are now linked to text where it is felt that such a link would be valuable to the reader.
8 ECRR 2010
3
Scientific Principles
Since a wise man may be wrong, or a hundred men, or several Nations, and since even human nature, as we know it, goes wrong for several centuries on this matter or on that, how can we be certain that it occasionally stops going wrong and that in this century it is not mistaken?
Montaigne 1533-92, The Essays
3.1 Radiation Risk and Scientific Method
The Committee believes that it is instructive to examine the scientific basis of the method which has been historically developed to create the radiation risk models.
The classical exposition of the scientific, or inductive method (originally due to William of Occam) is what is now called Mill’s Canons, the two most important of which are:
The Canon of Agreement, which states that whatever there is in common between the antecedent conditions of a phenomenon can be supposed to be the cause, or related to the cause, of the phenomenon.
The Canon of Difference, which states that the difference in the conditions under which an effect occurs and those under which it does not must be the cause or related to the cause of that effect.
In addition, the method relies upon the Principle of Accumulation, which states that scientific knowledge grows additively by the discovery of independent laws, and the Principle of Instance Confirmation, that the degree of belief in the truth of a law is proportional to the number of favourable instances of the law.
Finally, to the methods of inductive reasoning we should add considerations of plausibility of mechanism.
These are the basic methods of science (Mill, 1879; Harre, 1985; Papineau, 1996)
The questions of interest here are:
What are the health consequences of exposure to external radiation doses at levels below 2mSv, the approximate annual dose received from natural background?
What are the health consequences of exposure to novel internal radioisotope exposures at whole organism and individual organ dose levels below 2mSv?
Is the concept of dose applicable to internal radiation exposures?
Although risks from exposure to high levels of ionising radiation are generally accepted, since they are fairly immediate and visible, the situation with regard to low-level exposure is curious. There are now two mutually exclusive models describing the health consequences of such exposure. There
9 ECRR 2010
is the ICRP one, based on reductionist physics-based arguments and which is presently used to set legislation on exposure limits and argue that low-level radiation is safe, and one which is espoused by concerned independent public domain organisations and their associated scientists. These two models are shown schematically in Fig 3.1.
They arise from two different scientific methods. The conventional model is a physics-based one, developed by physicists prior to the discovery of DNA. Like all such models it is mathematical, reductionist and simplistic, and consequently has a powerful descriptive utility. Its quantities, dose, are average energy per unit mass or dE/dM and in its application, the masses used are greater than 1kg. Thus it would not distinguish between the average energy transferred to a man warming himself in front of a fire and a man eating a red hot coal. In its application to the problem at hand, the internal, low-level, isotopic or particulate exposure, it has been used entirely deductively. The basis of this application is that the cancer and leukemia yield per dose has been determined following the external acute high-dose irradiation by gamma rays of a large number of Japanese inhabitants of the towns of Hiroshima and Nagasaki. Together with this, other arguments based on averaging have been used to maintain that there is a simple linear relationship (in the low-dose region) between dose and cancer yield. This Linear No Threshold (LNT) assumption enables easy calculations to be made of the cancer yield of any given external irradiation.
By comparison, the mechanistic/epidemiological model shown at the bottom of Fig. 3.1 arises from an inductive process. There have been many observations of anomalously high levels of cancer and leukemia in populations living near nuclear sites, especially those where the measurements show that there is contamination from man-made radioisotopes, e.g. reprocessing plants. In addition there are populations who have been exposed to man-made radioisotopes from global weapons tests, downwinders living near nuclear weapon test sites, and those exposed to these materials because of accidents (like the Chernobyl infant leukemia cohort), or because of work in the nuclear industry or military. More recently, research has addressed those exposed to the fallout from the use of Uranium weapons: these have shown a wide range of genetic and neurological effects. A review of these findings is given later in this report. In contrast to the averaging approach of the conventional model, the biological model preferred by the ECRR considers each type of exposure according to its cellular radiation track structure in space and in time. Since ECRR2003 the effect of the absorbing element in the body has also become important. It is not easily possible to employ such a model to predict risks from unspecified ‘radiation dose’ to ‘populations’; rather it is concerned with microscopically described doses from specific isotopes or particles whose decay fractionations are considered to interact with cells which themselves respond biologically and biochemically to the insults and may be in various
10 ECRR 2010
stages of their biological development. The dose-response relationship following from this kind of analysis might be expected to be quite complex.
In examining radiation risk, the Committee finds that these philosophical models are mutually exclusive and has to decide which one is correct. In making such a decision the Committee has employed the basic rules of scientific method.
The Committee believes that the Linear No Threshold (LNT) model is fundamentally acceptable (with some reservations) in its application to acute, high dose, external irradiation, although it notes that the ICRP, UNSCEAR and BEIR Committees introduce a reduction of the modelled risk by a factor of 2 for low-dose-rate exposure, which breaks the assumption of linearity. The Committee believes that the extension of LNT to acute, external, low level radiation may be justified on the basis of theory, since the plausibility of the model rests on the idea of uniform density of radiation track events in microscopic tissue volumes. For chronic external irradiation, the Committee does not believe that the scientific method has been properly used to show that there is either epidemiological or theoretical justification for assuming a linear response at low doses. This is because the complex ways in which the organism responds to low-dose radiation both at the cell and at the organism level have been overlooked. However, the Committee believes that the errors introduced by the assumption are unlikely to be more than an order of magnitude.
The Committee is also concerned that the assumption of linearity of dose response is used to inform epidemiological studies of trend. A number of epidemiological studies have shown decreasing health effects at the highest doses and this finding has been used to suggest that radiation exposure cannot be responsible for the effects studied, although several plausible reasons for such a result (e.g. high-dose cell killing) may exist. The range of error for external irradiation effects and the mechanisms involved will be addressed in Chapter 9.
With regard to internal radiation doses, the Committee identifies a serious misuse of scientific method in the extension and application of the ICRP external model. Such a process involves deductive reasoning. It falsely uses data from one set of conditions— high-level, acute, external exposure— to model low-level, chronic, internal exposure. The procedure is scientifically bankrupt, and were it not for political considerations, would have been rejected long ago. On the other hand, it should be clear that the radical model shown in Fig 3.1, suggesting high risk, conforms to all the requirements of the scientific method listed at the beginning of this chapter. Man-made radioisotopes, often in the form of ‘hot particles’, are common contaminants of the areas near nuclear sites where there are cancer and leukemia clusters, and of nuclear site and test site downwinders, and of fallout-exposed populations. This satisfies the Canon of Agreement. The contingency analysis tables with control populations for such studies show that the Canon of Difference is also satisfied: people living in more remote regions than the downwinders show lower levels
11 ECRR 2010
of illness. The Principle of Instance Confirmation is fulfilled since so many studies have shown that increases in cancer and leukemia follow exposure regimes at low dose. We are left only with Plausibility of Mechanism, which will be addressed later in this report.
The Committee’s position on the scientific applicability of the ICRP model to the yield of fatal cancer in a range of exposure types is outlined in Table 3.1.
It is important to note that science and scientific conclusions are not the same as conclusions based on legal styles of evidential analysis. Science is not a simple question of weighing evidence for and against a theory or model of reality as it might be in a court of law or in everyday decision-making. The rules are strict. If one single piece of experimental evidence cannot be explained or incorporated into a theory, the theory has to be discarded (Kuhn 1962, Popper 1962). Therefore the existence of the nuclear site child leukemia clusters alone is enough to falsify (to prove wrong) the ICRP risk model; yet nothing has been done despite these data emerging in the 1980s. The Committee feels that it may be illuminating to ask how such a state of affairs, once set up in ignorance, becomes crystallised and difficult to challenge, even when large numbers of sick and dying draw attention to the existence of an insecure model. The conservative nature of science and its systems was considered in the late 1950s by an eminent and past member of the British Royal Society, the Nobel-Prize winner, chemist and economist Michael Polanyi.
Table 3.1 Errors associated with ICRP extension of acute high dose external studies to other types of exposure Type of exposure
Is ICRP model applicable?
Uncertainty in error factor for fatal cancer identified by ECRR
External acute >100mSv
Yes
0.5 to 25
External <100mSv
Very approximately but problems with cell and organism responses.
1 to 50
Internal <100mSv
No
1 to 2000
Internal
High Z elements
No
1 to 2000
http://www.euradcom.org/2011/ecrr2010.pdf
http://www.euradcom.org/2003/nouvellesnormes.htm
Commentaires récents