THE OTHER REPORT ON CHERNOBYL (TORCH)
AN INDEPENDENT SCIENTIFIC EVALUATION OF HEALTH AND ENVIRONMENTAL EFFECTS 20 YEARSAFTER THE NUCLEAR DISASTER PROVIDING CRITICAL ANALYSIS OF A RECENT REPORT BY THE
INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) AND THE WORLD HEALTH ORGANISATION (WHO)AUTHORS Ian Fairlie, PhD, UK. David Sumner, DPhil, UK
AFTERWORD Prof. Angelina Nyagu, Ukraine

Berlin, Brussels, Kiev, April 2006

COMMISSIONED BY Rebecca Harms, MEP, Greens/EFA in the European Parliament
WITH THE SUPPORT OF The Altner Combecher Foundation

Acknowledgements

This report was financed by Rebecca Harms, MEP, of the Greens/EFA Party in theEuropean Parliament and the Altner-Combecher Foundation.
The publishers are grateful in particular to Herr Günter Altner, Frau Altner and Herr Graf
Hatzfeldt for their support.
-----The authors thank Dr M DeCort of DG-TREN of the European Commission for permission
to reproduce plates from the Atlas of Caesium Deposition on Europe after the Chernobyl
Accident (1998) EUR Report 16733. Office for Official Publications of the European
Communities, Luxembourg. The authors also thank Dr Y Demidchik for permission to
reproduce figure 4.2.
The authors thank Dr K Baverstock, Professor Y Dubrova, U Fink and Dr W Neumann for
their helpful comments on drafts of the report. The authors also thank Dr E Cardis, Dr GN
Kelly, Dr E Lyman, Professor A Nyagu, Dr T Ruff, M Schneider, J Simmonds and others
for their helpful information. They also thank Margit Göbel, Silke Malorny and Anna
Turmann for their expert administrative help.
Any errors, of course, remain the sole responsibility of the authors.

2

Table of Contents
Acknowledgements..............................................................................................................2
Foreword by Rebecca Harms ..............................................................................................5
EXECUTIVE SUMMARY AND CONCLUSIONS .................................................................7

Chapter 1. Introduction ......................................................................................................14
AIMS OF THE REPORT .......................................................................................................14
SCOPE AND LIMITATIONS ...................................................................................................14
RADIATION AND RADIOACTIVITY .........................................................................................15
Uncertainty .................................................................................................................15
Difficulties with Epidemiology Studies.........................................................................16
Polarised Views on Radiation Risks ...........................................................................16
RECOMMENDED READING LIST ..........................................................................................18

Chapter 2. The Chernobyl Accident and Source Term ......................................................19
THE ACCIDENT .................................................................................................................19
SOURCE TERM .................................................................................................................20
Reactor Inventory .......................................................................................................22
RELEASE ESTIMATES FOR MAIN NUCLIDES .........................................................................23
Estimates for Cs-137 and I-131 ..................................................................................24
The Question of Plate-Out ..........................................................................................24
ANNEX 2A: EXCERPT FROM OECD/NEA (1995) ................................................................26
ANNEX 2B. ORIGINAL TABLE REPRODUCED FROM SICH (1996) .............................................27
ANNEX 2C. DERIVATION OF CS-137 AND I-131 SOURCE TERMS............................................28

Chapter 3. Dispersion and Deposition of Chernobyl Fallout ..............................................30
INTRODUCTION .................................................................................................................30
DEPOSITION DENSITY MEASUREMENTS ..............................................................................31
Official Reactions........................................................................................................36
CS-137 FROM TEST BOMB FALLOUT ..................................................................................36
CONTAMINATION LEVELS - WHAT DO THEY MEAN?...............................................................38
CS-137 CONTAMINATION ..................................................................................................39
EFFECTS THROUGHOUT EUROPE .......................................................................................41
CONTINUING HIGH LEVELS OF CONTAMINATION...................................................................42
RESTRICTED REPORTING BY UNSCEAR (2000) AND IAEA/WHO (2005A, 2005B) ...............43
ANNEX 3A. CHERNOBYL CONTAMINATION BY AREA IN EACH COUNTRY ...................................45
ANNEX 3B. FUTURE EFFECTS FROM CHERNOBYL ................................................................46

Chapter 4. Health Effects Resulting from the Chernobyl Accident.....................................47
INTRODUCTION .................................................................................................................47(1) THYROID CANCER .......................................................................................................48
How many more thyroid cancers can we expect? ......................................................50
Thyroid cancer in adults..............................................................................................51
3

Thyroid cancers outside Belarus, Ukraine and Russia ...............................................52(2) LEUKAEMIA .................................................................................................................53
Leukaemia in cleanup workers ...................................................................................53
Leukaemia in residents of contaminated areas ..........................................................53
Leukaemia in other European countries .....................................................................54(3) OTHER SOLID CANCERS................................................................................................55
Cancers in cleanup workers .......................................................................................55
Breast cancer in Belarus, Ukraine and Russia ...........................................................56
Bladder and Kidney Cancer........................................................................................56
Cancer in other European countries ...........................................................................56(4) NON-CANCER EFFECTS ................................................................................................56(a) Cataract Induction .................................................................................................57(b) Cardiovascular diseases .......................................................................................57(5) HERITABLE EFFECTS ....................................................................................................58(6) MENTAL HEALTH AND PSYCHOSOCIAL EFFECTS .............................................................59
ANNEX 4. RADIATION DOSE UNITS .....................................................................................60

Chapter 5. Collective Doses ..............................................................................................61
INTRODUCTION .................................................................................................................61
A. Collective Dose Estimates for Belarus, Ukraine and Russia ..................................62
B. Collective Doses in the Rest of Europe ..................................................................63
C. Collective Doses in the Rest of the World (excluding the whole of Europe)...........63
D. Global Collective Doses .........................................................................................64
COLLECTIVE DOSES FROM LONG-LIVED NUCLIDES..............................................................64
COMPARISON WITH OTHER RELEASES ................................................................................65
ANNEX 5A. BENNETT’S STUDY ...........................................................................................66
ANNEX 5B. COLLECTIVE DOSE ESTIMATES IN EUROPEAN COUNTRIES ...................................67

Chapter 6. Predicted Excess Cancer Deaths.....................................................................68
PREDICTIONS FOR BELARUS, UKRAINE AND RUSSIA.............................................................68
GLOBAL PREDICTIONS OF EXCESS CANCER DEATHS ...........................................................68
Radiation Risk Estimates and DDREFs......................................................................69
Inappropriate Comparisons with Background Radiation .............................................70
ANNEX 6A. COLLECTIVE DOSE AND THE LINEAR NO-THRESHOLD THEORY ............................71
ANNEX 6B. INAPPROPRIATE COMPARISONS WITH BACKGROUND RADIATION ..........................72

Chapter 7. Conclusions......................................................................................................73
Afterword ...........................................................................................................................76
References to Main Report ................................................................................................81
Acronyms and Abbreviations .............................................................................................914

Foreword by Rebecca Harms„There are two compelling reasons why this tragedy must not be forgotten. First, if we forget Chornobyl, we
increase the risk of more such technological and environmental disasters in the future. Second, more thanseven million of our fellow human beings do not have the luxury of forgetting. They are still suffering, every
day, as a result of what happened 14 years ago. Indeed, the legacy of Chernobyl will be with us, and with
our descendants, for generations to come."
Kofi Annan
UN Secretary General in April 2000
"We did not yet possess a system of imagination, analogies, words or experiences for the catastrophe ofChernobyl."
Svetlana Alexiyevich
Writer from Belarus

In August 1986, four months after the Chernobyl disaster, Morris Rosen, head of the Division of
Nuclear Safety of the Vienna based International Atomic Energy Agency (IAEA), declared: "Even if
there was a Chernobyl type accident every year, I would still consider nuclear power an interesting
type of energy production". 1 After a gigantic explosion and a ten day blazing fire had spread two
hundred times the amount of radioactivity of the combined releases of the Hiroshima and Nagasaki
bombs all over the planet, after the evacuation of over one hundred thousand people, the IAEA’s
chief nuclear safety officer considered an annual repetition of such a catastrophe an acceptable
hypothesis. This man was the most powerful person in the IAEA on the issue of nuclear safety
between 1981 and 1996, when he retired from his position then as Assistant Director General for
Nuclear Safety. Breathtaking.
Rosen’s post-Chernobyl declaration sheds a particular light on the mission statement of the IAEA,
which stipulates that the Agency “develops nuclear safety standards and, based on thesestandards, promotes the achievement and maintenance of high levels of safety in applications of
nuclear energy, as well as the protection of human health and the environment against ionizing
radiation”. Frightening.
When the IAEA in September 2005 released two reports on the environmental effects (coordinatedby the IAEA) and health impacts (coordinated by the World Health Organisation - WHO) of theChernobyl accident, numerous people and NGOs were suspicious about intentions and content.
The IAEA is not neutral. Its primary role, as defined on its website, is “to promote safe, secure andpeaceful nuclear technologies”. The IAEA led interagency cooperation with the WHO is not acoincidence. An 1959 agreement between both organisations stipulates: “Whenever eitherorganization proposes to initiate a program or activity on a subject in which the other organization
has or may have a substantial interest, the first party shall consult the other with a view to adjusting
the matter by mutual agreement.” The term is well chosen: “adjusting the matter”.
For the Swiss medical doctor Michel Fernex, the consequences are straight forward: “ThisAgreement explains why the WHO action plan for Chernobyl, IPHECA 2 , launched as late as
5 years after the catastrophe, was designed by the IAEA, it explains why the proceedings of the
WHO Chernobyl Conference (Geneva 1995) were never published, and why the inter-agency UN
report on Chernobyl 3 still indicates, against all evidence, that Chernobyl caused 32 deaths, 200
irradiated and 2,000 thyroid cancers (in children and teenagers only), those being the IAEA andUNSCEAR 4 figures, and not those of WHO and OCHA 5 .”1

Le Monde, 28 August 1986
International Programme on the Health Effects of the Chernobyl Accident
3
dated 6 February 2002
4
United Nations Scientific Committee on the Effects of Atomic Radiation
5
United Nations Office for the Coordination of Humanitarian Affairs
25

On 5 September 2005 an IAEA press release entitled “Chernobyl: The True Scale of the Accident”,
stated: “A total of up to four thousand people could eventually die of radiation exposure from the
Chernobyl nuclear power plant (NPP) accident nearly 20 years ago, an international team of morethan 100 scientists has concluded.”
The IAEA statement was widely disseminated by the international media and raised an outcry
amongst independent experts and environmental organisations that considered that the releasescandalously downplayed the true scale of the disaster. However a solid scientific critique was
missing.
I decided to commission an independent analysis of the IAEA/WHO reports in order to clarify thescience basis for the assertions. You are holding the result of the study, The Other Report on
Chernobyl or TORCH, by Ian Fairlie and David Sumner, in your hands. It becomes clear fromtheir conclusions that the IAEA had indeed issued a seriously misleading statement about the
WHO findings on health impact that forecasts, rather than 4,000, close to 9,000 excess cancer
deaths. However, other evaluations estimate the death toll from cancer alone to between 30,000
and 60,000, most of them outside the most intensely affected countries Ukraine, Belarus andRussia. In fact, the TORCH report also shows that more radioactivity was released from the reactor
than previously thought and that more than half of the fallout came down in Europe outside theformer Soviet Republics.
The excellent Afterword from renowned Ukrainian expert Prof. Angelina Nyagu, President of theKiev based association "Physicians of Chernobyl", reveals a number of additional issues that were
not the focus of the main report but highlight the scale of the ongoing drama. Ukrainian experts
estimate, for example, that the economic damage to Ukraine will be $200 billion until 2015. Incomparison, Ukraine’s GDP in 2001 was $37 billion. In 1992 Ukraine spent 15% of its State budget
dealing with the aftermath of Chernobyl. While the figure has dropped to 5% in recent years, there
are many issues that remain unresolved. Some of these are extremely urgent, including the factthat close to 10,000 people continue to live in zones of compulsory evacuation.
The present report cannot make up for the 20 years of systematic downplaying, secrecy,
misinformation and misunderstanding of the effects of the Chernobyl catastrophe. But it does makea significant contribution to the better understanding of what is at stake when the nuclear industry
and its lobby as well as some political leaders want us to agree to a new round of nuclear folly. It is
stunning to what extent the energy sector, in East and West, has never experienced its
Perestroïka, has never been exposed to Glasnost. It is the responsibility of political leaders to takeup the debate on energy policy and, beyond the commemorations of the 20th anniversary of what
will remain an ongoing disaster, guarantee a truly democratic decision making process that takes
into account the experiences from the past in order to design a sustainable energy future for all.
The aftermath of the Chernobyl disaster is far from mitigated. Not even on a technical level. The
conditions at the reactor site, in particular concerning spent fuel and waste management at theother three Chernobyl units, represent significant additional risks to be solved under very difficult
radiological conditions. However, nuclear waste and contamination in many other places aroundthe world from activities often decades ago still await a costly solution. Nobody can guarantee that
another accident of Chernobyl dimensions or worse won’t happen tomorrow. In most countries alarge majority of the people do not want any more nuclear power plants. It is about time thatindustrial, economic and political leaders listen. No more Chernobyl.

6

EXECUTIVE SUMMARY AND CONCLUSIONS
On 26 April 2006, twenty years will have passed since the Chernobyl nuclear power plant
exploded, releasing large quantities of radioactive gases and particles throughout thenorthern hemisphere. While the effects of the disaster remain apparent particularly in
Belarus, Ukraine and Russia, where millions of people are affected, Chernobyl’s fallout
also seriously contaminated other areas of the world, especially Western Europe.
The Other Report on Chernobyl (TORCH) provides an independent scientific examination of available data on the release of radioactivity into the environment and subsequent
health-related effects of the Chernobyl accident. The Report also critically examines recent
official reports on the impact of the Chernobyl accident, in particular two reports by the “UN
Chernobyl Forum” released by the International Atomic Energy Agency (IAEA) and theWorld Health Organisation (WHO) in September 2005 6 , which have received considerable
attention by the international media.
Many uncertainties surround risk estimates from radiation exposures. The mostfundamental is that the effects of very low doses are uncertain. The current theory is thatthe relationship between dose and detrimental effect is linear without threshold down tozero dose. In other words, there is no safe level of radiation exposure. However the risk, at
low doses, may be supralinear, resulting in relatively higher risks, or sublinear, resulting in
relatively lower risks.
Another major source of uncertainty lies in the estimates of internal radiation doses, that is,from nuclides, which are inhaled or ingested. These are important sources of the radiationfrom Chernobyl’s fallout. Uncertainties in internal radiation risks could be very large,
varying in magnitude from factors of 2 (up and down from the central estimate) in the mostfavourable cases, to 10 or more in the least favourable cases for certain radionuclides.

The Accident
Early on April 26 1986, two explosions in Chernobyl unit 4 completely destroyed thereactor. The explosions sent large clouds of radioactive gases and debris 7 - 9 kilometresinto the atmosphere. About 30% of the reactor’s 190 tons of fuel was distributed over thereactor building and surrounding areas and about 1-2% was ejected into the atmosphere.
The reactor’s inventory of radioactive gases was released at this time. The subsequentfire, fuelled by 1,700 tons of graphite moderator, lasted for eight days. This fire was theprincipal reason for the extreme severity of the Chernobyl disaster.

How Much Radioactivity Was Released?
The World Health Organisation (WHO) has estimated that the total radioactivity from
Chernobyl was 200 times that of the combined releases from the atomic bombs dropped
on Hiroshima and Nagasaki. The amount of radioactivity released during a radiologicalevent, is called the ‘source term’. It is important because it is used to verify nuclide
6

IAEA/WHO Health Effects of the Chernobyl Accident and Special Health Care Programmes. Report of the
UN Chernobyl Forum Expert Group “Health” (EGH) Working draft, July 26 2005. IAEA/WHO Environmental
Consequences of the Chernobyl Accident and their Remediation. Report of the UN Chernobyl Forum Expert
Group “Environment” (EGE) Working draft, August 2005

7

depositions throughout the northern hemisphere. From these, collective doses andpredicted excess illnesses and fatalities can be estimated.
Of the cocktail of radionuclides that were released, the fission products iodine-131,
caesium-134 and caesium-137 have the most radiological significance. Iodine-131 with its
short radioactive half-life 7 of eight days had great radiological impact in the short term
because of its doses to the thyroid. Caesium-134 (half-life of 2 years) and caesium-137(half-life of 30 years) have the greater radiological impacts in the medium and long terms.
Relatively small amounts of caesium-134 now remain, but for the first two decades after
1986, it was an important contributor to doses.
Most of the other radionuclides will have completely decayed by now. Over the next few
decades, interest will continue to focus on caesium-137, with secondary attention onstrontium-90, which is more important in areas nearer Chernobyl. Over the longer term
(hundreds to thousands of years), the radionuclides of continuing interest will be theactivation products, including the isotopes of plutonium, neptunium and curium. However,overall doses from these activation products are expected to remain low, compared withthe doses from caesium-137.
The authors have reassessed the percentages of the initial reactor inventories of caesium137 and iodine-131 which were released to the environment. They conclude that official
figures underestimate the amounts released by 15% (iodine-131) and 30% (caesium-137).

Dispersion and Deposition of Chernobyl Fallout
During the 10 day period of maximum releases from Chernobyl, volatile radionuclides were
continuously discharged and dispersed across many parts of Europe and later the entire
northern hemisphere. For example, relatively high fallout concentrations were measured at
Hiroshima in Japan, over 8,000 km from Chernobyl.
Extensive surveying of Chernobyl’s caesium-137 contamination was carried out in the
1990s under the auspices of the European Commission. The largest concentrations ofvolatile nuclides and fuel particles occurred in Belarus, Russia and Ukraine. But more thanhalf of the total quantity of Chernobyl’s volatile inventory was deposited outside thesecountries.
Russia, Belarus and Ukraine received the highest amounts of fallout while former
Yugoslavia, Finland, Sweden, Bulgaria, Norway, Rumania, Germany, Austria and
Poland each received more than one petabecquerel (1015 Bq or one million billion
becquerels) of caesium-137, a very large amount of radioactivity. 8
In area terms, about 3,900,000 km2 of Europe was contaminated by caesium-137 (above
4,000 Bq/m2) which is 40% of the surface area of Europe. Curiously, this latter figure
does not appear to have been published and, certainly has never reached the public’s
consciousness in Europe. Also 218,000 km2 or about 2.3% of Europe’s surface area wascontaminated to higher levels (greater than 40,000 Bq/m2 Cs-137 9 ). This is the area citedby IAEA/WHO and UNSCEAR, which shows that they have been remarkably selective intheir reporting.
7

Half-life is the time it takes for half of a given amount of a radionuclide to decay.
Cf. the EU limit of 600 Bq per kg of caesium-137 in dairy foods
9Compared with contamination levels in the Chernobyl exclusion zone > 555,000 Bq/m2.
88

In terms of their surface areas, Belarus (22% of its land area) and Austria (13%) weremost affected by higher levels of contamination. Other countries were seriously affected;
for example, more than 5% of Ukraine, Finland and Sweden were contaminated to highlevels (> 40,000 Bq/m2 caesium-137). More than 80% of Moldova, the European part ofTurkey, Slovenia, Switzerland, Austria and the Slovak Republic were contaminated tolower levels (> 4,000 Bq/m2 caesium-137). And 44% of Germany and 34% of the UK weresimilarly affected.
The IAEA/WHO reports do not mention these comprehensive datasets on European
contamination by the European Commission. No explanation is given for this omission.
Moreover, the IAEA/WHO reports do not discuss deposition and radiation doses in any
country apart from Belarus, Ukraine and Russia. Although heavy depositions certainly
occurred there, the omission of any examination of Chernobyl fallout in the rest of Europe
and the northern hemisphere is questionable.

Restrictions on Food Still in Place
In many countries, restriction orders remain in place on the production, transportation andconsumption of food still contaminated by Chernobyl fallout.
• In the United Kingdom restrictions remain in place on 374 farms covering 750 km2 and
200,000 sheep.
• In parts of Sweden and Finland, as regards stock animals, including reindeer, in naturaland near-natural environments.
• In certain regions of Germany, Austria, Italy, Sweden, Finland, Lithuania and Poland
wild game (including boar and deer), wild mushrooms, berries and carnivore fish fromlakes reach levels of several thousand Bq per kg of caesium-137.
• In Germany, caesium-137 levels in wild boar muscle reached 40,000 Bq/kg. The
average level is 6,800 Bq/kg, more than ten times the EU limit of 600 Bq/kg.
The European Commission does not expect any change soon. It has stated 10 :“The restrictions on certain foodstuffs from certain Member States must therefore
continue to be maintained for many years to come.” (emphases added)

The Health Impacts – So Far…
The immediate health impact of the Chernobyl accident was acute radiation sickness in
237 emergency workers, of whom 28 died in 1986 and a further 19 died between 1987 and2004. The long-term consequences of the accident remain uncertain. Exposure to ionisingradiation can induce cancer in almost every organ in the body. However, the time interval
between the exposure to radiation and the appearance of cancer can be 50 to 60 years or
more. The total number of cancer deaths from Chernobyl most likely will never be fully

10

Andris Piebalgs, European Commission, written answer to Question P-1234/05DE by MEP Rebecca
Harms dated April 4, 2005

9

known. However the TORCH Report makes predictions of the numbers of excess cancer
deaths from published collective doses to affected populations.
Thyroid Cancer
Up to 2005, about 4,000 cases of thyroid cancer occurred in Belarus, Ukraine and Russia
in those aged under 18 at the time of the accident. The younger the person exposed, thegreater the subsequent risk of developing thyroid cancer.
Thyroid cancer is induced by exposures to radioactive iodine. It is estimated that morethan half the iodine-131 from Chernobyl was deposited outside the former Soviet Union.
Possible increases in thyroid cancer have been reported in the Czech Republic and theUK, but more research is needed to evaluate thyroid cancer incidences in Western
Europe.
Depending on the risk model used, estimates of future excess cases of thyroid cancer
range between 18,000 and 66,000 in Belarus alone. Of course, thyroid cancers are also
expected to occur in Ukraine and Russia. The lower estimate assumes a constant relativerisk for 40 years after exposure; the higher assumes a constant relative risk over the wholeof life. Recent evidence from the Japanese atomic bomb survivors suggests that the latterrisk projection may be more realistic.
Leukaemia
The evidence for increased leukaemia is less clear. Some evidence exists of increased
leukaemia incidence in Russian cleanup workers and residents of highly contaminatedareas in Ukraine. Some studies appear to show an increased rate of childhood leukaemia
from Chernobyl fallout in West Germany, Greece and Belarus.
Other Solid Cancers
Most solid cancers have long periods between exposure and appearance of between
20 and 60 years. Now, 20 years after the accident, an average 40% increased incidence insolid cancer has already been observed in Belarus with the most pronounced increase in
the most contaminated regions. The 2005 IAEA/WHO reports acknowledge preliminary
evidence of an increase in the incidence of pre-menopausal breast cancer among women
exposed at ages lower than 45 years.
Non-Cancer Effects
Two non-cancer effects, cataract induction and cardiovascular diseases, are well
documented with clear evidence of a Chernobyl connection. Lens changes related toradiation have been observed in children and young people aged between 5 and 17 livingin the area around Chernobyl. A large study of Chernobyl emergency workers showed asignificantly increased risk of cardiovascular disease.

Heritable Effects
It is well known that radiation can damage genes and chromosomes. However the
relationship between genetic changes and the development of future disease is complex
and the relevance of such damage to future risk is often unclear. On the other hand, anumber of recent studies have examined genetic damage in those exposed to radiationfrom the Chernobyl accident. Studies in Belarus have suggested a twofold increase in the10germline minisatellite mutation 11 rate. Analysis of a cohort of irradiated families from
Ukraine confirmed these findings. However the clinical symptoms which may result fromthese changes remain unclear.
Mental Health and Psychosocial Effects
While seeming to downplay other effects, the recent IAEA/WHO reports clearly recognise
the vast mental, psychological and central nervous system effects of the Chernobyl
disaster: “The mental health impact of Chernobyl is the largest public health problem
caused by the accident to date. The magnitude and scope of the disaster, the size of theaffected population, and the long-term consequences make it, by far, the worst industrial
disaster on record.”
The origins of these psychosocial effects are complex, and are related to several factors,
including anxiety about the possible effects of radiation, changes in lifestyle – particularly
diet, alcohol and tobacco – victimisation, leading to a sense of social exclusion, and stressassociated with evacuation and resettlement. It is therefore difficult to state exactly how
much of these symptoms are directly related to Chernobyl related radiation exposures.

Collective Doses
Radiation exposures are mainly measured in two ways: individual doses and collective
doses. Individual doses are measured or calculated per person and collective doses are
the sum of individual doses to all exposed persons in a defined area, for example aworkforce, a country, a region, or indeed the world. The use of collective doses isparticularly relevant in cases where large population groups are exposed to relatively low
individual doses over long periods of time. The estimation of collective doses is anindispensable tool to evaluate potential future health effects of radiation.
It is necessary to identify clearly the time periods over which a collective dose is estimated.
For example, the exposed populations in Belarus, Ukraine and Russia received
approximately one third of a 70-year collective dose in the first year after Chernobyl.
Approximately another third was received in the next nine years (ie 1987 to 1996), andthe remaining third will be received approximately between 1997 and 2056.
The IAEA/WHO reports estimate the collective dose to Belarus, Ukraine and Russia is
55,000 person sieverts, which is the lower end of a range of evaluations reaching over
300,000 person sieverts. The IAEA/WHO restrict their time estimate to 2006, and fail topresent estimates for European and worldwide collective doses: these are significant
limitations.

The most credible published estimate for the total worldwide collective dose from
Chernobyl fallout is 600,000 person sieverts making Chernobyl the worst nuclear
accident by a considerable margin. Of this total collective dose, approximately:-

36% is to the populations of Belarus, Ukraine and Russia
53% is to the population of the rest of Europe
11% is to the population of the rest of the world 12

11

Human germline mutations are those that affect sequences of repeated DNA and thus the genes of thegerminal or reproductive cells (the egg and the sperm).

11

Estimated Future Excess Cancer Deaths
Excess cancer deaths can be estimated from published collective doses. For Belarus,
Ukraine and Russia, published estimates range between 4,000 and 22,000 excess cancer
deaths. For the world, published estimates range between 14,000 and 30,000. Theseestimates depend heavily on the risk factor used: different scientists use different factors.
Recent studies indicate that currently-used risks from low doses at low dose rates mayneed to be increased.
The IAEA, in its 5 September 2005 press release “Chernobyl: The True Scale of theAccident” stated that up to 4,000 people could eventually die of radiation exposure from
Chernobyl. This figure has been quoted extensively by the world media. However thestatement is misleading, as the figure calculated in the IAEA/WHO report is actually 9,000
fatalities.
Depending on the risk factor used (ie the risk of fatal cancer per person sievert), theTORCH Report estimates that the worldwide collective dose of 600,000 person sieverts
will result in 30,000 to 60,000 excess cancer deaths, 7 to 15 times the figure release in
the IAEA’s press statement.

Conclusions
The full effects of the Chernobyl accident will most certainly never be known. However,
20 years after the disaster, it is clear that they are far greater than implied by official
estimates. Our overall conclusion is that the unprecedented extent of the disaster and its
long-term global environmental, health and socio-economic consequences should be fully
acknowledged and taken into account by governments when considering their energy
policies.

In summary, the main conclusions of the Report are:• about 30,000 to 60,000 excess cancer deaths are predicted, 7 to 15 times greaterthan the figure of 4,000 in the IAEA press release• predictions of excess cancer deaths strongly depend on the risk factor used
• predicted excess cases of thyroid cancer range between 18,000 and 66,000 in
Belarus alone depending on the risk projection model12

It is remarkable that the author of these evaluations published in 1995 and 1996 (see hereunder), thathave not found their way into the 2005 IAEA/WHO studies, was also the Chairman of the Chernobyl Forumthat coordinated the 2005 IAEA/WHO studies.
• Bennett B (1995) Exposures from Worldwide Releases of Radionuclides. In Proceedings of anInternational Atomic Energy Agency Symposium on the Environmental Impact of Radioactive Releases.
Vienna, May 1995. IAEA-SM-339/185• Bennett B (1996) Assessment by UNSCEAR of Worldwide Doses from the Chernobyl Accident inProceedings of an IAEA Conference One Decade after Chernobyl: Summing up the Consequences of theAccident, Vienna, 8-12 April 1996.

12• other solid cancers with long latency periods are beginning to appear 20 years after
the accident• Belarus, Ukraine and Russia were heavily contaminated, but more than half ofChernobyl’s fallout was deposited outside these countries• fallout from Chernobyl contaminated about 40% of Europe’s surface area
• the most credible published collective dose is estimated to be about 600,000 person
sievert, more than 10 times greater than the 55,000 estimate by the IAEA/WHO in2005• about 2/3rds of Chernobyl’s collective dose was distributed to populations outside
Belarus, Ukraine and Russia, especially to western Europe• caesium-137 released from Chernobyl is estimated to be about a third higher thanofficial estimates
Recent IAEA/WHO studies
Our verdict on the two recent IAEA/WHO studies on Chernobyl’s health and environmental
effects respectively is mixed. On the one hand, we recognise that the reports containcomprehensive examinations of Chernobyl’s effects in Belarus, Ukraine and Russia. On
the other hand, the reports are silent on Chernobyl’s effects outside these countries.
However most of Chernobyl’s fallout fell outside Belarus, Ukraine and Russia. Collective
doses from Chernobyl’s fallout to populations in the rest of the world, especially in western
Europe, are twice those to populations in Belarus, Ukraine and Russia. This means thatthese populations will suffer twice as many predicted excess cancer deaths, as the
populations in Belarus, Ukraine and Russia.
The failure to examine Chernobyl’s effects in the other countries does not seem to lie withthe scientific teams but within the policy-making bodies of IAEA and WHO. In order torectify this omission, we recommend that the WHO, independently of the IAEA, shouldcommission a report to examine Chernobyl’s fallout, collective doses and effects in the restof the world, particularly in western Europe.
___________________________________________

13

Chapter 1. Introduction
1.
On April 26 2006, 20 years will have passed since the world’s worst industrial
accident. The disaster is now a generation away, yet the word ‘Chernobyl’ still resonates
throughout the world, and its effects are still apparent particularly in Belarus, Ukraine andRussia, the three countries most affected by the disaster. As this report will show,
Chernobyl fallout also seriously contaminated other areas of the world. In the United
Kingdom, for example, over 2,500 kilometers from Chernobyl, more than 360 farms arestill subject to restrictions because of Chernobyl contamination. Ultimately, fallout from
Chernobyl was distributed over the entire northern hemisphere.

Aims of the Report
2.
The report aims to provide an impartial scientific examination of mainly healthrelated effects of Chernobyl, and to critically examine recent official reports on Chernobyl
from a European point of view. Although the subject matter of the report is clearlyscientific, we have tried to write the report in plain English ensuring we explain our terms
and avoid jargon, in order to make the report more accessible to members of the public. In
some cases, the complexity of the matter may have defeated our intentions, but we have
tried to keep the report simple and understandable.
3.
The five main chapters of the report cover source term matters, dispersal anddeposition issues, health effects, collective doses and predicted excess cancer deaths.
Chapter 2 discusses official estimates of the total amount of radioactivity released by the
explosions and subsequent fire at Chernobyl. This chapter derives our own estimates of
the releases of the most important nuclides, Cs-137 and I-131, which are greater thanofficial estimates. Chapter 3 illustrates the extremely wide diffusion of Chernobyl fallout
over Europe and the northern hemisphere. Chapter 4 discusses the incidences of thyroid
cancer, leukaemias, solid cancers and non-cancer effects appearing in Belarus, Ukraine
and Russia and elsewhere. Chapter 5 estimates collective dose estimates world-wide, andChapter 6 predicts excess cancer deaths from Chernobyl fallout.

Scope and Limitations
4.
Several hundred official and unofficial reports and books have been written about
Chernobyl. Web searches for the word “Chernobyl” reveal over 38,000 scientific citationsin Google Scholar and about 3,000 peer-reviewed articles in scientific journals in PubMed(http://www.ncbi.nlm.nih.gov/entrez/). Therefore it was necessary to focus on what to us
were the most important issues: source term, dispersal and deposition, health effects,
collective doses and predicted excess cancer deaths. Unfortunately, the time available did
not permit us to examine the socio-economic effects of the disaster, the ecologic effects(see Moller and Mousseaux, 2006; Moller et al, 2005) and the present state of thedestroyed reactor at Chernobyl and its sarcophagus. These serious subjects deserve
detailed examination in other reports.
5.
Our emphasis on a scientific approach means that we have relied mainly on
scientific articles published in peer-reviewed journals. Mainly but not exclusively: we havealso referenced articles from non-published sources including the websites of a number ofinternational research institutes. Our main criteria for inclusion were whether the authors
had approached their subject critically and had been scientifically rigorous with their14evidence. Inevitably, there remains an element of subjectivity in our choice of references,and there may well be articles which have escaped our attention.
6.
In addition, our work has been inevitably limited by the difficulties in gaining access
to, and translating, many scientific reports written in Ukrainian and Russian. These
constraints inhibit a full understanding of the impacts of Chernobyl, and we draw attention
to this difficulty and to the need for it to be tackled at an official level. Our research has
also been limited by the failure to publish their findings on cancer incidences - for example,
the ECLIS programme on childhood leukaemias in European countries. Also, our report isa ‘snapshot’ of a moving scene: much Chernobyl-related research is still underway andnew findings may well change our understanding of radiation’s effects, just as they have inthe past 20 years.

Radiation and Radioactivity
7.
Radiation and radioactivity (including their risks, doses, biology and epidemiology)
are complex matters which are not easily understood. This brief report does not discussradiation and radioactivity in detail as this would require a book in itself. However we doprovide a note on radiation dose units (see Annex 4), a list of acronyms (see end of report)
and a reading list of the more critical articles and books for those interested in learning
more about radiation (see end of this chapter). Perhaps the most recent and accessible
introduction to radiation and radioactivity in English is the report of the UK Government’s
Committee Examining the Radiation Risks of Internal Emitters (CERRIE, 2004) which canbe downloaded from www.cerrie.org. The CERRIE Committee contained independentscientists and representatives of environmental organisations as well as scientists fromofficial agencies: its report therefore contains a spectrum of views.
8.
Although we do not discuss radiation per se, we should mention some ancillarymatters to radiation, including uncertainty, the limitations of epidemiology and the wide
disparity of views on radiation risks.
Uncertainty
9.
Many uncertainties surround risk estimates from radiation exposures. The mostfundamental is that we are unsure of the dose-response relationship at very low doses.
The current theory is that this relationship is linear without threshold down to zero dose
(Brenner et al, 2003). However it may be supralinear resulting in higher risks, or sublinear
resulting in lower risks. See discussion in Annex 6A. The result is that risk estimates fromexposures to radiation inevitably contain uncertainties. This does not prevent such
estimates being made, but they have to be treated with caution.
10.
Another main source of uncertainty lies in our estimates of internal radiation doses,that is, from nuclides which are inhaled or ingested. These are an important source of theradiation impact resulting from Chernobyl fallout. This issue was comprehensively
examined in the 2004 CERRIE report which concluded that uncertainties in the internal
dose coefficients 13 for some nuclides could be very large. The uncertainties in internalradiation risks could also be large, varying in magnitude from factors of 2 (up and downfrom the central estimate) in the most favourable cases, to 10 or more in the least
favourable cases. These uncertainties depended on factors such as the type ofradionuclide, its chemical form, the mode of exposure and the body organ under13

a dose coefficient expresses the dose given by one decay of a radionuclide in Sv per Bq

15

consideration. Under some circumstances, equivalent doses could be substantially greateror smaller than current best estimates; therefore great care has to be taken when judging
the risks of radioactive sources inside the body.
11.
The CERRIE report also advised that a precautionary approach should be used. In
our view, this means that we should err on the side of caution - in other words, we should
be aware that doses and risks might be greater than those presently used.
Difficulties with Epidemiology Studies
12.
For a number of reasons, epidemiology studies are a blunt tool for discovering
whether adverse effects result from particular exposures. One reason is that manymethodological difficulties can exist with epidemiology studies. For example, muchepidemiology data on Chernobyl is descriptive (or ecological) with poor case identification,
non-uniform registration, variable or uncertain diagnostic criteria and uncertainties in theuniformity of data collation. Predicted excess deaths are often uncertain due to
confounding factors, competing causes of death and different risk projection models. For
example, one difficulty in interpreting Chernobyl mortality studies is the large recent
decrease in average lifespan in all three countries occurring in all areas not just thecontaminated ones.
13.
Only very large, expensive and lengthy epidemiology studies are able to reveal
effects where the signal (added cancers) is weak, and the noise (large numbers of natural
cancers) is strong. Often, we see instead many small studies each showing perhaps a few
extra cases which prove little. Meta-studies which group together small studies in order tostrengthen their statistical significance are a solution, but few have been carried out so far.
In addition, various agents can produce significant bias in studies. For example, smoking
and alcohol cause major increases in overall mortality and morbidity, and in cancer andcardiovascular disease. Another problem is establishing causality. This often requires
estimating doses in order to show a dose – effect relationship. However, as shown by the
CERRIE report, there are often large uncertainties in estimating doses - especially frominternal radiation sources which are important in Chernobyl exposures.
14.
The conclusion is that there needs to be more awareness of the many factors thathave to be taken into account when considering epidemiology studies. In particular, theresults of epidemiology studies need to be interpreted with care.
Polarised Views on Radiation Risks
15.
Widely different views exist on radiation risks between the authors of many official
publications and members of the public especially in Belarus, Ukraine and Russia. In
addition, the contents of many unofficial websites reveal a lack of knowledge about
radiation and its effects among many members of the public, often coupled with anapparent fear of radiation. It’s also apparent that a substantial number of people in
Belarus, Ukraine and Russia – as in most of the EU Member States – are suspicious ofGovernments and official agencies with pro-nuclear policies, seeing them as having aninterest in minimising the effects of radiation and controlling public perceptions about therisks. They are therefore often hostile towards official publications on radiation risks whosefindings, in their view, do not match their own experiences.
16.
Many unofficial accounts have criticised official reports on the health effects from
Chernobyl, in particular for their reluctance to acknowledge the existence of increased16

effects and their practice of denying links between such increases and radiation from theaccident. Notably, during the IAEA/WHO Conference on Chernobyl in Vienna in
September 2005, officials from health ministries and academic institutions in Belarus andUkraine spoke out against the refusals of their Governments and international agencies torecognise what was, in their view, the true scale of Chernobyl’s effects.
17.
Outspoken criticisms have been made by Malko (1998b) who has accused theinternational radiation protection community of being unable to objectively assess thehealth consequences of the accident. He has stated that the international radiation
protection community had attempted to play down the consequences from the beginning.
He gave numerous examples of official refusals to accept the existence of data from theirown health ministries and of their far-fetched explanations for observed effects. Perhaps
the most disheartening example was the WHO’s initial explanation in 1992 for the large
increases in childhood thyroid cancer in Belarus. These were allegedly due to (a) the
administration of prophylactic iodine to children after the accident and (b) nitrates in foodbrought into the country from Asia (Nucleonics Week, 1992).
18.
Some agencies have dramatically changed their views on radiation’s effects,
without discussing the reasons for doing so. One example is the decision by UNSCEAR
after about 1998 not to discuss global collective doses from Chernobyl - see chapter 5. In
addition, some Governments and official agencies have refused to recognise the data andreports by other official agencies. The Director General of the IAEA, Mr Elbaradei
highlighted this when he stated (IAEA/WHO, 2005b)“…a lack of trust still prevails … due in part to contradictory data and reports on the
precise environmental and health impacts of the accident, among national
authorities as well as among the relevant international organizations”
19.
One should tread warily in this battleground of views and values. Nevertheless, it isworth pointing out that, while many official reports contain equivocations, omissions,misleading language and understatements, others are more forthright and transparent. In
our experience, a significant minority of scientists working in official international andnational agencies do not necessarily agree with the downplaying of radiation effects. In
other words, it would be unwise to reject all official reports, as they sometimes containvaluable information and insights. What are needed instead are critical and discriminating
examinations of official reports. We have attempted to do this here, while avoiding both theunderstatements in official reports and the discussions of effects clearly not due toradiation in unofficial reports.

17

Recommended Reading List
Caufield C (1990) Multiple Exposures: Chronicles of the Radiation Age. Penguin Books.
London UK
CERRIE (2004) Committee Examining the Radiation Risks of Internal Emitterswww.cerrie.org
Gofman JW (1981) Radiation and Human Health. A Comprehensive Investigation of the
Evidence Relating Low-level Radiation to Cancer and Other Diseases. Sierra Club Books.
San Francisco
Greenberg M (1991) The Evolution of Attitudes to the Human Hazards of Ionising
Radiation and to its Investigators. Am J of Industrial Medicine Vol 20 pp 717-721
Greene G (1999) The Woman Who Knew Too Much. University of Michigan Press. Ann
Arbor, MI, US
Lambert B (1990) How Safe is Safe? Radiation Controversies Explained. Unwin. London
UK (Out of print but copies may be available in libraries. A good introduction but now out ofdate.)
Proctor RN (1995) Cancer Wars: How Politics Shapes What We Know and Don’t Know
about Radiation. Basic Books. New York, NY, US
Rose G (1991) Environmental Health: Problems and Prospects. J of Royal College ofPhysicians of London Vol 25 No 1, pp 48-52
Stewart AM (1991) Evaluation of Delayed Effects of Ionising Radiation: an Historical
Perspective. Am J of Industrial Medicine Vol 20 pp 805-810
Sumner DS, Watson D and Wheldon T (1994) Radiation Risks. Tarragon Press. (Out of
print but copies may be available in libraries. A good introduction but now out of date.)
US EPA website contains a relatively unbiased but basic description of radiation and its
effects http://www.epa.gov/radiation/understand/index.html

18Chapter 2. The Chernobyl Accident and Source Term
The Accident
1. In April 1986, the world’s worst industrial accident occurred at the Chernobyl nuclear
power plant in Ukraine. The IAEA (1996) has described it as the “foremost nuclear
catastrophe in human history” which resulted in the “largest regional release ofradionuclides into the atmosphere.” WHO (IPHECA, 1995) has estimated that, althoughdifferent radionuclides were released, the total radioactivity of the material from Chernobyl
was 200 times that of the combined releases from the atomic bombs dropped on
Hiroshima and Nagasaki. The disaster not only resulted in an unprecedented release ofradioactivity but also a series of unpredicted and serious consequences for the public andthe environment.
2. Early on April 26, an explosion occurred in Chernobyl reactor 4 followed moments later
by a second explosion. The explosions completely destroyed the reactor, sheared allpressure tubes and water coolant channels, and dislodged the upper biological shieldweighing 1,400 tonnes. The resulting damage is shown in Figure 2.1. The explosions senta large cloud of radioactive fission products and debris from the core and reactor 7-9
kilometres into the atmosphere (UNSCEAR, 1988). About 30% of the reactor’s fuel was
sprayed over the reactor building and surrounding areas and about 1-2% was ejected into
the atmosphere. Most of the reactor’s inventory of radioactive gases was released at thistime.
Figure 2.1 Cross-section view of Chernobyl Unit 4 reactor

3. Worse was to follow. About a day later, combustible gases from the disrupted corecaught fire producing flames that reached 50 m (UNSCEAR, 2000) above the reactor. This19

ignited the graphite moderator containing 1,700 tonnes (Hohenemser, 1988) of carbon
which subsequently burned for 8 days. As explained in the OECD/NEA (1995) account(see Annex 2A), the long-lasting graphite fire was the main reason for the extreme severityof the Chernobyl disaster. The graphite fire ceased when all the carbon had been burned.
Revealingly, the phrase “graphite fire” does not appear in the UNSCEAR (2000) andIAEA/WHO (2005a and 2005b) reports.
4. Much of the heat generated by the graphite fire, by radioactive decay, and possibly bycontinuing fission in the remaining fuel was retained by the graphite mass. As a result,temperatures in the destroyed core rose to 2,500°C according to analyses of dispersed
fuel particles by Devell et al (1986) 14 . These temperatures led to the melting of the fuelremaining in the stricken reactor (metallic uranium melts at 1130°C; zirconium at 1850°C),
the total release of gaseous nuclides and the vaporisation, to varying degrees, of volatileand less volatile nuclides. After vaporisation, it is assumed that some plating out occurredon cooler parts of the shattered reactor and its debris: much uncertainty surrounds thefractions of nuclides which condensed in this way.
5. After about 9 days, the temperature of the molten fuel rose sufficiently high to melt thereactor’s lower biological shield allowing the remaining molten fuel to flow into
subterranean chambers beneath the reactor. Here the fuel cooled and solidified into lavalike formations which remain today. Many reports state that this evacuation is the reason
for the significant reduction in radionuclide emissions after the tenth day.
6. Nuclide emissions continued sporadically for a further 20 to 30 days but on a much
reduced scale. At the end, the reactor core contained neither fuel nor graphite moderator.
During the fire, many tonnes of borated lead and other materials were dropped byhelicopter into the reactor in an attempt to extinguish the graphite fire but it appears little
reached its target: most fell to one side (Sich, 1996). See figure 2.1. Annex 2A contains atechnical description of the disaster by the OECD/NEA (1995) which reveals the serious
predicaments resulting from the catastrophic events of April/May 1986.

Source Term
7. Much debate has surrounded the magnitude of the Chernobyl “source term,” that is, theamount of radioactivity released from the Chernobyl disaster. Although many reports havebeen written on Chernobyl’s radioactive releases, unfortunately they often raise as manyquestions as answers. The source term is important because it can be used to verify
nuclide depositions throughout Belarus, Ukraine, Russia, the rest of Europe 15 and thenorthern hemisphere. From these, collective doses and predicted excess deaths may be
estimated.
8. Source terms may be estimated in two main ways(i) The first is to use computer programs which model the atmospheric dispersal ofpollutants. Fallouts are averaged over blocks of territory and are integrated overspace and time. Early efforts at assessing radioactivity source terms using thesemodels produced very low estimates. This was partly because the blocks used were
too large in space and time, and partly because rainfall was very localized, so
14

Devell et al collected and analysed radioactive fuel particles by electron microscopy. They concluded fromtheir form and composition that the temperature in at least part of the reactor core reached ~2,500°C.
15“Europe” has a slightly elastic geographical extent. In this report, Europe extends eastwards to the Ural
mountains, that is, it includes some of Russia, all of Ukraine, and all of Belarus.

20

average deposition densities over large areas were inaccurate. Later, moresophisticated attempts were made using extensive gamma measurements andmapping techniques with satellite Geographic Information Systems (European
Commission, 1998).
(ii) The second is to estimate the amounts of fission and activation products in thereactor before the accident by using computer programs (such as FISPIN,
ORIGEN2, etc) which calculate fuel isotope inventories in reactors. The source termis the difference between the reactor fuel's isotope inventory and the estimatedamounts of nuclides in the fuel remaining beneath or nearby the reactor.
Both methods have their drawbacks, particularly their use of questionable assumptions,and both produce estimates with significant uncertainties. The second method produces
more realistic estimates and is perhaps burdened with fewer uncertainties.
9. The source term was not used in estimating doses to the affected populations in thethree former Soviet republics of Belarus, Ukraine and Russia: these were derived frommeasured nuclide concentrations and dose reconstructions. Here, measured
concentrations were used with external and internal dose factors 16 to estimate doses overvarious time periods. This method has been criticised because of the lack of data on the
habits and diets of local populations: these data are important in assessing internal doses
from ingestion and inhalation of nuclides which are responsible for about half of theradiation dose to inhabitants of heavily contaminated areas.
10. In the early years after Chernobyl, large uncertainties existed in initial estimates of thefuel inventory and the amounts which remained, due to the inaccuracy and inadequacy of
the Soviet data provided at the time. In subsequent years, later estimates were made(reviewed by Khan, 1990) using the second of the above methods. Ten years later,
attempts were made to harmonise estimates and develop a consensus view on the source
term (see Devell et al, 1995), which were only partially successful. At the same time,reports by Sich (1994, 1994a, 1996) and Borodin and Sich (1996) gave additional
information on the fate of the fuel in the stricken reactor.
11. In 2000, UNSCEAR estimated that the total radioactive material released from
Chernobyl was 12 x 1018 becquerels (Bq) 17 including 6.5 x 1018 Bq of noble gases, mainly
krypton and xenon (12 x 1018 means 12 followed by 18 zeroes). According to UNSCEAR(2000), 100% of gases, and 20 - 60% of volatile radionuclides, were released into theatmosphere and carried for large distances. In addition, ~30% of the reactor’s fuel wasejected to areas around the reactor during the initial explosions and ~1 - 2% of the fuelwas more widely dispersed.
12. UNSCEAR (2000) did not discuss a number of studies - see table 2.2 – which citedlarger releases of important nuclides. The UNSCEAR (2000) conclusions were
subsequently reiterated in the WHO/IAEA (2005a) report without qualification or
discussion. In our view, there is no up-to-date critical discussion of the Chernobyl source
term that takes these factors into account. The present report tries to fill this gap and, inparticular, attempts to estimate the amounts of Cs-137 and I-131 released from Chernobyl.

16

which relate the absorbed dose in Sv to the degree of land contamination
the amount of a radionuclide is expressed in terms of its 'activity', that is, the number of spontaneous
nuclear disintegrations per second releasing radiation. Its unit is the becquerel (Bq). 1 Bq = 1 disintegration
per second.
17

21

Reactor Inventory
13. The reactor contained about 190 tonnes of nuclear fuel, 1,700 tonnes of graphite
moderator, and a very large volume of cooling water. The fuel elements mainly consistedof mainly (>95%) uranium oxide. The reactor had been operating since 1983 and its fuelhad an average burnup of 11 GWdays per tonne. Therefore it contained considerable
quantities of fission products (eg caesium-137) and activation products (eg plutonium 239).
The explosions ejected about a third of the fuel, mostly to nearby areas; the continuing
graphite fire resulted in much wider releases of fission and activation products.
14. The fission products iodine-131, caesium-134 and caesium-137 have the mostradiological significance. Iodine-131 with its short radioactive half-life of 8 days had thegreater radiological impact in the short term because of its doses to thyroid. Caesium-134(half-life = 2 years) and caesium-137 (half-life = 30 years) have the greater radiologicalimpacts in the medium and long terms. Very small amounts of Cs-134 now remain but for
the first two decades after 1986, it was an important contributor to doses because of its
relatively high dose coefficient 18 . Although strontium-90 also has a relatively long half-lifeof 29 years and a high dose coefficient, measurements indicate that relatively little (~5%)
was released as it is less volatile. Most was deposited within 100 km or so of the reactor.
Also relevant are tellerium-132 (half-life = 3.3 days) as the parent of I-132 (half-life = 2.3
hours), and Te-129m (half-life = 33.6 days) as the parent of I-129 (half-life = 16 million
years).
15. The latest official estimates (UNSCEAR, 2000; IAEA/WHO, 2005b) of initial nuclide
inventories and activities released for the most relevant nuclides are set out in table 2.1.
The percentages released were omitted in the official reports but they have been
calculated (by dividing each nuclide’s release by its initial inventory) and are presented in
the final column. Note that many of the official figures are qualified by the tilde sign “~”,meaning “approximately”. Percentage releases are discussed further in paragraphs 19 and
20 below.
16. Some tables in this report contain greyed columns or cells. These contain data or
estimates prepared by this report. Normal unshaded columns contain data or estimatesfrom other reports.
Table 2.1 Initial nuclide inventories and amounts released for key nuclides released
from Chernobyl
PBq = 1015 Bq
RadionuclideHalf-life

Core Inventory on April 26
1986 - PBq

Activity Released -PBq

Estimated Percentage
Released

INERT GASES
Kr-85
Xe-13310.72 a5.25 d33
6,500

Te-129m
Te-132
I-129

1040
4200
-5
8.1 x 10

I-131
I-133
Cs-134
Cs-136
Cs-13733.6 d3.26 d15,700,000a8.04 d20.8 h2.06 a13.1 d30.0 aSr-89
Sr-90
Ru-103
Ru-106
Ba-14050.5 d29.12 a39.3 d368 d12.7 d

33
6,500

100
100

240
~1,150-5~8 x 10

23
~27
~50

VOLATILE ELEMENTS

18

3180
~1,760
6700
2,500
150
~54
110
36
260
~85
ELEMENTS WITH INTERMEDIATE VOLATILITY
3960
~115
220
~10
4810
>168
850
>73
4800
240

~56
37
~36
33
~33
~3
~4.5
>3.5
>8.6
5

ie high values of Sv per Bq (delivering high radiation doses to persons who inhale or ingest the nuclide)22

RadionuclideHalf-life

Zr-95
Mo-99
Ce-141
Ce-144
Np-239Pu-238
Pu-239Pu-240Pu-241
Pu-242
Cm-24264.0 d2.75 d32.5 d284 d2.35 d87.74 a24,065 a
6,537 a14.4 a376,000 a
18.1 aCore Inventory on April 26
1986 - PBq

Activity Released -PBq

Estimated Percentage
Released

REFRACTORY ELEMENTS (incl fuel fragments***)
4810
196
5550
> 168
5550
196
3920
~ 116
58,100
945
0.93
0.035
0.96
0.03
1.5
0.042
190
~6
0.00210.00009
31
~0.9

4
>3
3.5
~3
1.6
3.7
3
3
~3.2
4.3
~3

sources: UNSCEAR (2000) and Dreicer et al (1996)*** Based on fuel particle release of 1.5% (Kashparov et al, 2003)
Shaded column – derived in this report by dividing column 4 values by column 3 values

17. Most of the radionuclides in table 2.1 will have completely decayed by now. Over the
next few decades, interest will continue to focus on Cs-137, with secondary attention on
Sr-90 which is more important in areas near Chernobyl. Over the longer term (hundreds tothousands of years), the radionuclides of continuing interest will be the activation products,
including the isotopes of plutonium, neptunium and curium. The only radionuclide
expected to increase in the coming years is americium-241 which arises from the decay ofplutonium-241; the amount of americium-241 will reach a maximum about 100 years after
1986. Doses from americium-241 are expected to be small in comparison with those fromCs-137.

Release Estimates for Main Nuclides
18. Our focus is primarily on the main nuclides mentioned above: tables 2.2 and 2.3 set out
published estimates of the percentages released and source terms.
Table 2.2 Estimates of percentage of core inventory released
Study
Cs-137
Cs-134
Sr-90
I-131
Te-132US DoE
40% - 60%
40% - 60%
40% - 60%
40% - 60%
Anspaugh et al, 1988
Gudikson et al, 1989
40%
40%
60%
Seo et al, 1989
57%
9%
70%
OECD, 1995
20%-40%20%-40%
4%-6%
50%-60%25-60%2
Sich, 1996
30%
33%
41%
15%
Devell et al, 1996
33%+10%1
33%+10%1
4% -6%
50% - 60%
25-60%2
Borovoi et al, 2001
33%±10%33%±10%50% - 60%
UNSCEAR, 2000
~33%
36%
~4.5%
~56%
~27%
IAEA/WHO, 2005b
1 table data in Devell et al, 1996 states “+” without explanation
2 Devell et al (1996) report that Te-132 air samples above the reactor and in Nordic countries indicated arelease fraction 1 to 2 times that of caesium.

Table 2.3 Estimates of released nuclides from Chernobyl – PBq
Study
Sorenson,1987
US DoE(Anspaugh et al, 1988)
Aarkrog, 1994
OECD, 1995
UNSCEAR, 2000
IAEA/WHO, 2005b

Cs-137
100
98

Cs-134
-

Sr-90
-

I-131
-

Te-132
-

100
~85
~85

50
~54
~54

8
~10
~10

~1,760~1,760~1,150~1,15023

19. Tables 2.2 and 2.3 indicate that the percentage of the core inventory Cs-137 released
ranged between 20% - 60%, ie between 85 -100 PBq. For iodine, the percentages
released ranged between 40% and 70%, and the amount was ~1,760 PBq according to
UNSCEAR (2000).
20. Given the length and severity of the graphite fire during which temperatures rose to2500°C, it may be expected that more than a third of the Cs inventory may have beenreleased. Caesium is volatile: metallic caesium melts at 28°C and boils at 671°C, althougha range of Cs compounds with higher melting points would have been present in themolten fuel. Even more volatile is iodine which has an elemental melting point of 114ºC
and and a boiling point of 185ºC. In our view, therefore, the above IAEA/WHO percentage
release figures may be underestimates. Because of its importance, we investigate thematter further.
Estimates for Cs-137 and I-131
21. Detailed analyses of the source terms for the main nuclides were carried out by Sich
(1994, 1996) and Borovoi and Sich (1996). Using photographic evidence andmeasurements of heat flux and radiation intensities, Sich and Borovoi estimated that 135
tonnes of melted nuclear fuel, that is 71% of the initial inventory of 190 tonnes, remained
under the reactor. Other researchers have suggested different values. Purvis (1995)
estimated between 27-100 tonnes and Kisselev et al (1995, 1996) reported that only 24
tonnes could be identified visually. These differences clearly require further study andexplanation.
22. Sich estimated the nuclide concentrations remaining in two compartments (a) the fuelremaining below the reactor, and (b) the fuel ejected by the explosions. The fuel in the firstcompartment released its volatile nuclides during the 10 day period before the melting of
the lower biological shield and the subsequent draining of molten fuel into chambers below
the reactor. The fuel in the second compartment would have released its volatile nuclides
primarily during the two explosions.
23. In the first compartment, Sich’s measurements indicated that 35% 19 of the fuel’s
original Cs-137 remained in the solidified fuel lava, ie 65% had been volatilised. Borovoi
and Gagarinski (2001) later estimated that 60% had been volatilised. In the second
compartment, ie the fuel ejected by the explosions and fires, Sich estimated that only 30%
of its caesium content was volatilised.
The Question of Plate-Out
24. Sich further assumed that, during the 10 day period of maximum releases, 50% of thevolatilised caesium and iodine would have “plated-out” on adjacent structures, ie
precipitated on cooler surfaces. As far as we are aware, this assumption does not appear
to be backed by evidence or arguments. Sich’s assumption of 50% plate-out in the firstcompartment is questionable for many reasons, including

19

Sich stated the 0.35 fraction was “surprising”, in other words, it was an unexpectedly large amount, and hesurmised that the carbon moderator in the stricken reactor had acted to filter and retain Cs isotopes during
the 7 day fire. However this filtration did not occur with other nuclides: for example over 95% of (less volatile)
ruthenium isotopes were released, cf 65% of caesium isotopes.

24• the 2500°C temperatures (Devell et al, 1986) 20 attained in the reactor with similar
temperatures in the structures above it.
• the destroyed reactor - see Figure 2.1 - reveals few structures above the reactor
on which plate-out could occur.
• some plate-out may have occurred when temperatures were low. However, as
temperatures rose throughout the 10 days, earlier plated isotopes may have been
revaporised.
• UNSCEAR 2000 (Volume II, page 455, paragraph 15) states “The very hightemperatures in the core shaft would have suppressed plate-out of radionuclides
and maintained high release rates of penetrating gases and aerosols.”• Sich uses only 10%, not 50%, plate-out for his second compartment.
• Sich states his estimates of fractional releases are “probably quite low” and thosefor plate-out are “probably high”. See footnote (a) to his original table in Annex 2B.
• his release estimates are low compared with other estimates using the same
method.
25. Despite his unrealistic values for plate-out, Sich’s overall methodology is useful.
Therefore we have used this to derive better estimates of the source terms for Cs-137 andI-131 in Annex 2C. For Cs-137, our estimated range of the percentage released is 37% 49% with a point estimate of 43%. This is the same as the higher value of the range 23%
to 43% cited by UNSCEAR (2000) and IAEA/WHO (2005b) – see table 2.2. It lies within
the 40-60% range estimated by Anspaugh et al (1988) for the US Department of Energy see table 2.3. In Bq terms, our estimate for Cs-137 lies in the range of 95 -128 PBq with apoint estimate of 110 PBq. This is about a third greater than the UNSCEAR (2000)
estimate and is closer to the 98 PBq estimate estimated by the US DoE (Anspaugh et al,1988).
26. For I-131, our estimated range is 54% to 75% released with a point estimate of 65%.
This is slightly higher that the 56% release estimated by UNSCEAR (2000), but similar to
the estimates by Gudikson et al (1989) and Seo et al (1989). Because of the greater
uncertainties with iodine releases, only UNSCEAR has made an estimate of the Bqamount released - 1,760 PBq - see table 2.3. Our estimated range for I-131 is 1,700 to
2,300 PBq with a point estimate of 2,000 PBq which is 14% higher than the UNSCEAR(2000) estimate. These estimates will have uncertainties attached to them mainly from theplate-out fractions

20

Devell et al (1986) collected and analysed radioactive fuel particles by electron microscopy. They
concluded from their form and composition that the temperature in at least part of the reactor core reached2,500°C.

25

Annex 2A: Excerpt from OECD/NEA (1995)“The Accident
The accident occurred at 01:23 on Saturday, 26 April 1986, when the two explosions destroyed the core of
Unit 4 and the roof of the reactor building. In the IAEA Post-Accident Assessment Meeting in August 1986
(IA86), much was made of the operators’ responsibility for the accident, and not much emphasis was placedon the design faults of the reactor. Later assessments suggest that the event was due to a combination of
the two, with a little more emphasis on the design deficiencies and a little less on the operator actions.
The two explosions sent a shower of hot and highly radioactive debris and graphite into the air and exposed
the destroyed core to the atmosphere. The plume of smoke, radioactive fission products and debris from thecore and the building rose up to about 1 km into the air. The heavier debris in the plume was deposited close
to the site, but lighter components, including fission products and virtually all of the noble gas inventory were
blown by the prevailing wind to the North-west of the plant. Fires started in what remained of the Unit 4building, giving rise to clouds of steam and dust, and fires also broke out on the adjacent turbine hall roof
and in various stores of diesel fuel and inflammable materials. Over 100 fire-fighters from the site and calledin from Pripyat were needed, and it was this group that received the highest radiation exposures andsuffered the greatest losses in personnel. These fires were put out by 05:00 hr of the same day, but by thenthe graphite fire had started. Many firemen added to their considerable doses by staying on call on site. The
intense graphite fire was responsible for the dispersion of radionuclides and fission fragments high into theatmosphere. The emissions continued for about twenty days, but were much lower after the tenth day when
the graphite fire was finally extinguished.
The Graphite Fire
While the conventional fires at the site posed no special fire fighting problems, very high radiation doses
were incurred by the firemen. However, the graphite moderator fire was a special problem. Very little national
or international expertise on fighting graphite fires existed, and there was a very real fear that any attempt to
put it out might well result in further dispersion of radionuclides, perhaps by steam production, or it mighteven provoke a criticality excursion in the nuclear fuel.
A decision was made to layer the graphite fire with large amounts of different materials, each one designed
to combat a different feature of the fire and the radioactive release. Boron carbide was dumped in large
quantities from helicopters to act as a neutron absorber and prevent any renewed chain reaction. Dolomite
was also added to act as heat sink and a source of carbon dioxide to smother the fire. Lead was included asa radiation absorber, as well as sand and clay which it was hoped would prevent the release of particulates.
While it was later discovered that many of these compounds were not actually dropped on the target, they
may have acted as thermal insulators and precipitated an increase in the temperature of the damaged coreleading to a further release of radionuclides a week later.
By May 9, the graphite fire had been extinguished, and work began on a massive reinforced concrete slab
with a built-in cooling system beneath the reactor. This involved digging a tunnel from underneath Unit 3.
About four hundred people worked on this tunnel which was completed in 15 days, allowing the installation of
the concrete slab. This slab would not only be of use to cool the core if necessary, it would also act as abarrier to prevent penetration of melted radioactive material into the groundwater.
In summary, the Chernobyl accident was the product of a lack of "safety culture". The reactor design waspoor from the point of view of safety and unforgiving for the operators, both of which provoked a dangerous
operating state. The operators were not informed of this and were not aware that the test performed could
have brought the reactor into explosive conditions. In addition, they did not comply with establishedoperational procedures. The combination of these factors provoked a nuclear accident of maximum severity
in which the reactor was totally destroyed within a few seconds.”

26

Annex 2B. Original table reproduced from Sich (1996)(NB. This original table contains a mathematical mistake. The fig for I-131 in the lastcolumn should be 34.5 not 24.5 MCi.)27

Annex 2C. Derivation of Cs-137 and I-131 source terms(i) Tables 2C(i) and 2C(ii) set out our calculations for Cs-137 and I-131 releases using
Sich’s methodology but with a range of reasonable parameter values. In particular, we
assume values of between 20% and 50% plate-out for the first compartment. In addition,
we use the later value of 60% estimated by Borovoi and Gagarinski (2001) as the Cs
release fraction for both compartments.
Table 2C(i) - Estimated Cs-137 releases using Sich’s methodology and a range ofreasonable assumptions for plate-out fraction in the first compartment (in bold)First Compartment
AuthorInitialActivityThis
report

260
PBq

This
reportSecond Compartment

Fraction
Fuel
below
reactor.71

Fraction
Released(1Plateout)

Released

Fractionof FuelejectedFraction
Released(1Plateout)

ReleasedTotal
Cs-137
release% of core
inventory
released.6
Borovoi= 88 PBq.29.6
Borovoi.9Sich= 40 PBq

128
PBq

49%

260
PBq

.71

.6
Borovoi= 77 PBq.29.6
Borovoi.9Sich= 40 PBq

117
PBq

45%

This
report

260
PBq

.71

.6
Borovoi= 66 PBq.29.6
Borovoi.9Sich= 40 PBq

106
PBq

41%

This
report

260
PBq

.71

.6
Borovoi= 55 PBq.29.6
Borovoi.9Sich= 40 PBq

95 PBq

37%

Sich

260
PBq

.71

.65
Sich

.8
this
report.7
thisreport.6
thisreport.5
thisreport.5
Sich= 60 PBq

.29

.3
Sich

.9
Sich

= 20 PBq

80 PBq31%(ii) To help, we shall work through an example. Go to the first row starting with “Thisreport” on the extreme left. Moving to the right into the green section, we multiply the initial
260 PBq in the reactor x 0.71 x 0.6 x 0.8 to arrive at 88 PBq released from compartment 1.
In the yellow section, we multiply the initial 260 PBq x 0.29 x 0.6 x 0.9 to get 40 PBq
released from compartment 2. Adding the green and yellow PBq values, we arrive at the
total of 128 PBq in the penultimate column. This is 49% of the initial 260 PBq in the final
column.
(iii) For Cs-137, from table 2C(i), our estimated range of the percentage released is 37% 49% with a point estimate of 43%. This is the same as the higher value of the range 23%
to 43% cited by UNSCEAR (2000) and IAEA/WHO (2005b). In Bq terms, our estimate for
Cs-137 lies in the range of 95 -128 PBq with a point estimate of 110 PBq. This is about athird greater than the UNSCEAR (2000) estimate and is closer to the 98 PBq estimate
derived by Anspaugh et al (1988) for the US Department of Energy.
(iv) For I-131, in table 2C(ii) we use the later findings by Borovoi and Gagarinski (2001)
that no I-129 was found in the fuel below the reactor, indicating all the I-131 was released
from the first compartment. We also use their findings that 25% - 37% (average ~30%) of
the original I-131 remained in the ejected fuel indicating that an average of 70% of the I131 was released from the second compartment.

28

Table 2C(ii). Estimated I-131 releases using Sich methodology and a range ofreasonable assumptions for plate-out fraction in the first compartment (in bold)First Compartment
Fraction Fraction
Fuel
Releasedbelow
reactor.71
1
Borovoi

AuthorInitialActivityThis
report

3080
PBq

This
report

3080
PBq

.71

1
BorovoiThis
report

3080
PBq

.71

1
BorovoiThis
report

3080
PBq

.71

1
Borovoi

Sich
1996

3080
PBq

.71

.8
.Sich

Second Compartment
Fraction Fraction(1of Fuel
Released Plateejectedout)(1Plateout)

Released

ReleasedTotal
Cs-137
release% of core
inventory
released.8
thisreport.7
thisreport.6
thisreport.5
thisreport
.5
Sich

=1750
PBq

.29

.7
Borovoi

.9
Sich

=563
PBq

2313
PBq

75%

=1530
PBq

.29

.7
Borovoi

.9
Sich

=563
PBq

2093
PBq

68%

=1294
PBq

.29

.7
Borovoi

.9
Sich

=563
PBq

1857
PBq

60%

=1093
PBq

29

.7
Borovoi

.9
Sich

=563
PBq

1656
PBq

54%

=875
PBq

.29

.5
Sich

.9
Sich

=402
PBq

-

41%

(v) For I-131, from table 2C(ii), our estimated range is 54% to 75% released with a point
estimate of 65%. This is slightly higher that the 56% release estimated by UNSCEAR(2000), but similar to the estimates by Gudikson et al (1989) and Seo et al (1989).
Because of the greater uncertainties with iodine releases, only UNSCEAR has made anestimate of the Bq amount released - 1,760 PBq - see table 2.3. Our estimated range for I131 is 1,700 to 2,300 PBq with a point estimate of 2,000 PBq which is 14% higher than the
UNSCEAR (2000) estimate.

29

Chapter 3. Dispersion and Deposition of Chernobyl Fallout
Introduction
1. During the 10 day period of maximum releases from Chernobyl, volatile radionuclides
were continuously discharged into the atmosphere. During this period, the prevailing windschanged direction frequently with the result that the radioactive plume was widely spreadand Chernobyl’s nuclide emissions were dispersed across many parts of Europe, and later
across the entire northern hemisphere. For example, relatively high concentrations of
nuclides from the Chernobyl plume were measured at Hiroshima Japan, over 8,000 km
from Chernobyl (Kiyoshi, 1987). European dispersal is shown in the satellite pictures fromthe Lawrence Livermore Research Laboratory in the US, reproduced from OECD/NEA(2002) in Figure 3.3.

Figure 3.1 Areas covered by the main body of Chernobyl radioactive clouds on
successive days during the releaseon April 26, 1986

on April 30, 1986

on April 28, 1986

on May 2, 198630

on May 4, 1986

on May 6, 1986

original source: ARAC, Lawrence Livermore Research Laboratory, California, US
reproduced from OECD (2002)
2. Initially, the dry deposition of volatile radionuclides from the Chernobyl plume acrossEurope and the northern hemispheres was modelled by a number of authors (seediscussion in UNSCEAR, 1988 and Hohenemser, 1988). However, rainfall resulted inmarkedly heterogeneous depositions of fallout throughout Europe and the northernhemisphere. Most ejected fuel was deposited in areas near the reactor with wide variations
in deposition density, although some fuel hot particles were transported thousands ofkilometres. The heaviest concentrations of nuclides and fuel particles were deposited in
Belarus, Russia and Ukraine. More than half of the Cs-137 source term was deposited incountries outside Belarus, Ukraine and Russia (see table 3.6 below): as an approximation,
it is assumed that all volatile radionuclides were similarly dispersed.
3. An important characteristic of fallout is solubility in water as this determines the initialmobility and bioavailability of deposited radionuclides in soils and surface waters after
deposition. In fallout sampled at Chernobyl, water-soluble and exchangeable forms of Cs137 varied from 5% to >30% (Bobovnikova et al, 1991). Water-soluble and exchangeable
forms of Sr-90 deposited on 26 April accounted for only about 1%, but increased to 5% –10% in subsequent days due to the smaller size of particles emitted by the graphite fire. At
further distances, the fraction of soluble condensed particles increased considerably
because of their smaller particle sizes: for example almost all Cs-137 deposited in 1986 in
the United Kingdom was water-soluble and exchangeable (Hilton et al, 1992).
4. Radiation exposures to humans from Chernobyl occurred via four main pathways(i) External exposures by the Chernobyl plume as it passed overhead(ii) Inhalation of nuclides in the plume(iii) Continuing external radiation from nuclides deposited on the ground(iv)Ingestion of contaminated foodAt the time of the accident, pathways (i) and (ii) were very important, especially (ii) for
thyroid doses. Twenty years later, pathways (iii) and (iv) are the main contributors to dose.

Deposition Density Measurements
5. Between 1995 and 1998, the European Commission and Member States measured
Cs-137 contamination levels throughout Europe using extensive gamma measurementsfrom low altitude flights (EC, 1998). The quality of the EC mapping was determined largely
31

by the density of sampling and measurement points. Hundreds of thousands ofmeasurements were carried out in Ukraine, Belarus, Russia and Sweden by aero-gamma
surveys conducted on map scales of 1:200k and 1:1,000k at flight altitudes of 50 -150 m.
About 10,000 soil samples were taken in Central and Western European countries. The
territories of Norway, Finland, UK, Greece, Germany, the Netherlands, Austria, andSwitzerland were investigated most thoroughly. The EC’s comprehensive contamination
data for Cs-137 concentrations above 4 kBq/m2 are reproduced in table 3.1 below.
6. The contamination data were mapped and Figure 3.2 reproduces plate 1 from EC,
1998. This indicates the very widespread nature of Cs-137 contamination throughout
Europe.
Figure 3.2 Caesium-137 contaminated areas in European countries

reproduced with permission from De Cort et al, 1998
7. In addition, particularly large areas of Belarus, Ukraine and Russia were contaminatedwith high levels of radioactivity, as shown in figures 3.3, 3.4 and 3,5.

32

Figure 3.3 Caesium-137 contaminated areas in Belarus

reproduced with permission from De Cort et al, 1998
Figure 3.4 Caesium-137 contaminated areas in Ukraine

reproduced with permission from De Cort et al, 1998
33

Figure 3.5 Caesium-137 contaminated areas in former USSR

reproduced from IAEA/WHO (2005b)
34

Table 3.1 Areas contaminated by Caesium-137 in European countries
Areas (1,000 km2) contaminated above specified levels (kBq/m2)
Country
Russia(European part)UkraineRomania
NorwayFinlandGermany
SwedenBelarus
Italy
PolandUnited Kingdom
Austria
GreeceCzech Rep
FranceLithuania
Ireland
Croatia
Slovak Rep
Switzerland
Hungary
Moldova
Turkey(European part)
LatviaSlovenia
Estonia
Denmark
Netherlands
Luxembourg
Belgium
Totals

4-10
2
kBq/m
1110

10-20
2
kBq/m
250

20-40
2
kBq/m
180

40-1002
kBq/m
44100-185
2
kBq/m
7.2

185-555
2
kBq/m
5.9

555-1480
2
kBq/m
2.2

>1480
2
kBq/m
0.46

Totals

240
120
89
50
110
55
50
37
71
64
17
37
42
54
48
47
29
32
26
29
13
23

120
54
44
32
29
31
22
37
10
15
28
21
13
1.2
0.05
1.3
11
6.8
6.4
5.2
19
0.04

43
13
23
59
14
33
16
15
3.5
1.7
25
8.3
3.5
0
0
0.01
0.03
0.61
2.3
0.23
1.9
0

29
1.2
7.1
19
0.32
23
21
7
0.52
0.09
11
1.2
0.21
0
0
0
0
0.02
0.73
0
0
0

4.3
0
0.08
0
0
0.44
8.7
1.3
0
0.04
0.08
0.04
0.01
0
-

3.6
0
0
0
0
>0.01
9.4
0.05
0
0.03
-

0.73
4.4
-

0.56
0
2.6
-

441
188
163
160
153
142
134
97
85
81
81
68
59
55
48
48
40
39
35
35
34
23

21
2.5
8.7
0.8
0.64
0.12
0.09
2427

0
8.1
1.7
767

0
8.7
0.28
452

0
0.61
0
0
0
0
0
166

22

19

7

3.62

21
20
11
0.8
0.64
0.12
0.09
3,864

1600

source: EC (1998)
greyed column inserted by the authors of this report

8. The data in the final column in table 3.1 was calculated by adding the data in thecolumns to the left. The final column indicates that the European area contaminated by
Chernobyl (above the 4 kBq/m2 Cs-137 level) is about 3,900,000 km2, which is about 40%of the surface area of Europe (9,700,000 km2). This percentage is surprisingly large, yet it
was not reported in the 1998 EC report, and to our knowledge, it has not appeared in any
other official publications.
9. Of this total, 218,000 km2, or about 2.3% of Europe’s surface area was contaminated tolevels greater than 40 kBq/m2. This is the area cited by the IAEA/WHO and UNSCEAR
reports. Therefore it is seen that IAEA/WHO and UNSCEAR have been economical with
their use of the available data, to say the least, as they have chosen to report upon only
highly contaminated areas.
10. A more detailed table showing the percentage areas of each country affected by
Chernobyl contamination is contained in Annex 3A. This indicates that Belarus and Austria
were the countries most affected by higher levels of contamination (>40 kBq/m2 Cs-137) interms of area. However, other countries were seriously affected; for example, more than
5% of Ukraine, Finland and Sweden were contaminated to high levels. Annex 3A also
reveals that > 80% of the surface areas of Moldova, Turkey (the European part), Slovenia,

35

Switzerland, Austria, and the Slovak Republic were contaminated to lower levels (>4kBq/m2 Cs-137) and that 44% of Germany and 34% of the UK were similarly affected.
Official Reactions
11. When the accident occurred in 1986, many governments denied or minimised theaccident’s effects (Medvedev, 1990). This was particularly true of the former Soviet Union,
but it was by no means the only country in denial. The UK Government, for example, wasaccused of minimising Chernobyl’s effects (Edwards, 1989) and misleading the public(Weaver, 1986). In France, allegations were recently made in legal proceedings byenvironmental groups 21 that French official bodies had suppressed information about the
spread of radioactive fallout over France from the Chernobyl disaster. In December 2005,
the magistrate investigating the allegations, Maitresse Marie-Odile Bertella-Geffroy,
handed over a report she had commissioned from two independent scientists, Paul Genty
and Professor Gilbert Mouthon at Chimie et Physique Biologiques et Medicales, ENVA,
France. This stated that the French Government’s Central Service for Protection against
Radiation (SCPRI) had known of high levels of contamination in Corsica and south-easternFrance but had kept the details under wraps. Instead it had issued imprecise maps thatconcealed high levels of fallout in certain areas. The case is continuing (The Australian,2005).

Cs-137 from Test Bomb Fallout
12. Considerable amounts of Cs-137 were deposited on Europe by fallout from the atomic
bomb tests in the 1950s and 1960s, and residual low levels of between 0 and 3.5 kBq per
m2 still existed in 1986, as shown in figure 3.6.

21

including CRIIRAD, AFMT and about 200 plaintiffs

36

Figure 3.6 Test bomb Cs-137 levels in Europe before Chernobyl

reproduced with permission from De Cort et al, 1998
13. These test bomb concentrations need to be considered when estimating Chernobyl
depositions. It is for this reason that table 3.1 above is restricted to data for concentrations
greater than 4 kBq/m2. In fact, the relevant table in the EC report cites concentrations forbelow 4 kBq/m2 down to 0 - 1 kBq/m2. In our view, the interpretation of such low-level data
(0-4 kBq/m2) is difficult because of the possible presence of test bomb Cs-137: accordingly
they are not cited here. We acknowledge that this is a somewhat arbitrary decision, but inour view a cut-off level has to be applied, otherwise one could be measuring mostly bomb
Cs-137 rather than Chernobyl-related Cs-137.
14. Nevertheless, in terms of actual amounts deposited, more Cs-137 from Chernobyl was
deposited (at concentrations lower than 4 kBq/m2) over Europe than is shown in table 2.1
above. In other words, the area values of Chernobyl contamination in table 2.1 should beconsidered minimum values. Unfortunately, a further complication exists with the EC’s
methodology for estimating Cs-137 levels: this is discussed in paragraphs 22-23.

37

Contamination Levels - What do they mean?
15. Table 3.2 sets out the definitions of the contamination zones in Belarus, Ukraine andRussia.
Table 3.2 Zones of contamination in Belarus, Russia and Ukraine
Contamination density Official designation of zones
Cs-137 (Ci/km2 )Belarus*
Russia**Ukraine***1-5

Periodic radiation monitoring

5-15

Zone with the right to resettle

15-40

Zone of secondary
resettlement
Zone of priority resettlement>40

Privileged socioeconomic status
Right to resettle (ifdose > 1 mSv/year)
Mandatory
resettlement if 137Cs>40 Ci/km2 or dose
>5 mSv/a. Voluntary
if below thisResettlement zone
(exclusion zone)

Territories adjacent toZone of evacuation
Chernobyl (including 30-km (exclusion zone)zone). Population
evacuated 1986 - 1987
sources: * Goskomchernobyl, 2001 ** Russian Federation, 1992 *** Ukraine, 2001

Zone of enhanced
radiological control
Zone of guaranteed
resettlement
Zone of obligatory
resettlement

Exclusion zone

16. After the Chernobyl accident, the then Soviet Union introduced various criteria for
managing contaminated areas. It established 1 curie (Ci) per km2 (equal to 40 kBq/m2) as
the lowest Cs-137 contamination level at which occasional controls were required:
voluntary resettlement was permitted above this level in practice. Stricter controls wereapplied in more heavily contaminated areas. Subsequently, the 1 curie level was adopted
by Belarus, Ukraine and Russia. It is often viewed as a “safe” level by the media andpublic, but in fact this is not the case. It is merely an administrative number, arbitrarily
chosen most probably for its convenience, being 1 curie per km2. The reality is that there is
no absolutely “safe” level of exposure to radioactivity. No matter how low the level, somesmall risk will accrue. To determine how much and to establish whether this is acceptable,
it is necessary to estimate the radiation doses from external exposures to radioactive Cs137, which we do in the next paragraph.
17. In système internationale (SI) units, 1 curie per km2 is 40 kBq/m2 rounded to one
significant figure 22 . This concentration means that an area of one square meter would, on
average, emit the external beta and gamma radiation from 40,000 Cs-137 decays eachsecond. Determining the annual external radiation “dose” from external contamination is
not straightforward and depends on many factors, such as whether people live and workoutside, and whether they live in wooden or concrete homes, etc. Table 3.3 sets out official
estimates of external dose coefficients expressed in microsieverts (µSv) per kBq/m2 of Cs137 in the year 1996 from UNSCEAR (2000). This indicates an approximate average doseof 10 µSv per kBq/m2 per year in 1996.

22

1.0 curie is equal to 3.7 x 109 becquerels. But since the administrative limit is expressed as a single digit,
ie 1 (and not 1.0), the equivalent is more correctly expressed as 4 x 109 Bq.

38

Table 3.3 Official estimates of absorbed dose rate in air / Cs-137 density(Normalized absorbed dose rate in air in 1996)[Columns 1 and 2 are the same annual dose rates expressed in different units. Column 1
is expressed in nGy per hour per kBq/m2. Column 2 is expressed in µGy per year per
kBq/m2.]
Column 1
Column 2
Country
Dose rate
Dose rate(nGy per hour per kBq/m2 Cs-137)(µGy per year per kBq/m2 Cs-137)
Belarus1.0
8.7
Russia0.85
7.4
Ukraine1
1.5
13
Ukraine2
1.1
9.6
average
9.7
estimates from table 32 of UNSCEAR (2000)
estimates in greyed column estimated by the authors of this report

18. From table 3.3, we can derive an average dose conversion factor 23 of about 10 µSv per
year per kBq/m2 of Cs-137. Although some uncertainty is inevitably associated with thisdose conversion factor, we derive an approximate dose estimate of 0.4 mSv per year fromexternal exposures to 40 kBq/m2 of Cs-137 for rural workers in Belarus, Ukraine andRussia. This is about the same level as the annual dose constraint of 0.3 mSv used in the
UK for the regulation of radiological practices: doses to critical groups above this constraint
are not authorised. Other countries maintain more stringent limits. For example, guidancefrom the US Environmental Protection Agency (US EPA, 1997) on minimum clean-up
levels for radioactively contaminated sites stipulates a maximum dose of 0.15 mSv per
year. This equates to a lifetime risk of fatal cancer of 3 x 10-4 (assuming a risk of 5% per
Sv over 40 years) and achieves an excess upper-bound lifetime cancer risk of 10-4 to 10-6
which is applied to all carcinogens in the US 24 .
19. Similarly, a contamination level of 4 kBq/m2 means that an area of one square meter
would, on average, emit the external radiation from 4,000 Cs-137 decays each second.
Using the above dose coefficient results in an external dose of about 0.04 mSv per annum.
This is a relatively “low” dose of radiation, about the same as the radiation dose from achest X-ray in a modern hospital 25 . Assuming a linear no-threshold dose-response
relationship, some health effects (ie a low number of additional cancers) would occur fromexternal exposures at these levels, although it would be almost impossible to ascertain
these small numbers of increased cases by means of epidemiology studies. To assess
health effects correctly in these situations of low radiation doses, we need to estimate
collective doses – see Chapter 5.

Cs-137 Contamination
20. The countries in table 3.1 are ranked by the size of their contaminated areas. This isinteresting, but it hides large variations in the amounts of Cs-137 (in Bq) deposited in eachcountry. These amounts are shown in tables 3.4 and 3.5 which rank countries by the Bqamounts of Cs-137 contamination. These data are from two sources EC (1998) and US
23

in theory, this should be multiplied by ~0.9 to convert Gy to Sv, but we shall not introduce this factor here.
in 2005, the UK Government proposed new limits allowing permanent habitation on radioactively
contaminated land where annual doses did not exceed 10 mSv. However these have been objected to byenvironmental groups, and they have not been implemented as of the date of drafting this report.
25
although this has a countervailing benefit for the individual who is X-rayed, and no benefit accrues to those
exposed by Chernobyl releases.
24

39

DoE (1987). Most data are from the EC Atlas but this does not cover Bulgaria, Albania andmost of former Yugoslavia which are covered in the US data. The EC data includes
amounts from areas with very low Cs-137 concentrations, ie 0 - 4 kBq per m2.
Table 3.4 Cs-137 deposition
ranked by country
Country
Russia (Europe part)
Belarus
UkraineFinlandSwedenNorwayRumania
Germany
Austria
PolandGreece

PBq
29
15
13
3.8
3.5
2.5
2.1
1.9
1.8
1.2
0.95

Country
Italy
FranceUnited Kingdom
Czech Rep
Lithuania
Moldova
Slovenia
Spain
Croatia
Switzerland
Hungary

PBq
0.93
0.93
0.88
0.6
0.44
0.4
0.39
0.38
0.37
0.36
0.35

Country
Ireland
Slovak Rep
LatviaEstonia
Turkey (Europe part)
Denmark
Netherlands
Belgium
Luxembourg
Total

PBq
0.35
0.32
0.25
0.18
0.16
0.087
0.062
0.053
0.008
85

data reproduced from table III.1 in EC, 1998

Table 3.5 Cs-137 deposition
ranked by country
Country
PBq
Yugoslavia
5.4
Bulgaria
2.7
Albania
0.4
TOTAL
8.5
data reproduced from US DoE, 1987
[Yugoslavia reduced by 0.76 PBq to avoid double-counting Slovenia and Croatia in table 3.4]

21. These tables indicate that the three former Soviet Union republics received the highest
Bq amounts of Cs-137 fallout and that former Yugoslavia, Finland, Sweden, Bulgaria,
Norway, Rumania, Germany, Austria and Poland each received more than 1 PBq (1015
Bq) Cs-137, which is a large amount of radioactivity (cf the EU limit of 600 Bq per kg of Cs137 in dairy foods see table 4.2).
22. As shown in table 3.4, the total Cs-137 deposited on Europe was estimated by the EC(1998) to be 85 PBq. An additional 8.5 PBq should be added to include Chernobyl fallout
on Yugoslavia, Bulgaria and Albania, giving a total of ~94 PBq in Europe. The EC reportstated that Cs-137 previously deposited on Europe from test bomb fallout in 1950s and1960s should be deducted from these estimates. In 1996, about 20 PBq remained fromthis fallout. However, a problem exists with the EC’s methodology for arriving at the latter
estimate. The EC report stated that the average estimated contribution from weapons
fallout in each 1 x 1 km area cell was subtracted from the total caesium-137 estimated forthe same cell. Nevertheless, where the average fallout level exceeded the total deposition,
the contribution from Chernobyl was assumed to be zero. The report admitted that, as aresult,“this approach has clear limitations and may result in large uncertainties in
estimates of the amount of Chernobyl caesium-137 deposited in some countries.
These uncertainties will be greatest for those countries with the lowest levels of
deposition. ….this aspect warrants further attention in future with a view to making
more rigorous estimates of Chernobyl deposition in the less affected countries.”
23. So there are uncertainties in the EC’s estimates of the amounts of caesium-137 fromresidual test bomb fallout and of the Chernobyl caesium-137 amounts in some countries.
40

This means that the EC’s deposition estimates are unsuitable for estimating the Chernobyl
source term, and in fact the EC report refrains from doing this.

Effects throughout Europe
24. The high levels of contamination from Chernobyl resulted in countermeasures andrestrictions on the use of contaminated foodstuffs being introduced in many areas ofEurope. Some of these restrictions are continuing to this day because unexpectedly highlevels of Cs-137 remain in the plants and soils of upland pastures. It was discovered thatacid soils promote the mobility and bioavailability of Cs and that many grass plants on
upland pastures accumulate it. These findings apply to varying extents to such countries
as the UK and Ireland. These findings are one of a number of surprising new findings
resulting from the Chernobyl accident.
25. In the United Kingdom, approximately 2,500 km from Chernobyl, fallout was deposited
on sheep-grazing upland areas in Wales, Cumbria and Scotland following heavy rainfall.
As a result, 8,900 farms were placed under restriction. In particular, the movement, saleand slaughter of 4,225,000 sheep were restricted in order to stop contaminated animals
from entering the food chain. As of 2005, these restrictions remain on 375 farms and
215,000 sheep (RIFE, 2005).
26. Similar situations exist in parts of Sweden and Finland as regards stock animals,
including reindeer, in natural and near-natural environments. From a 2002 survey in EU
Member States, wild game (including boar and deer), wild mushrooms, berries andcarnivore fish from lakes in certain regions of Germany, Austria, Italy, Sweden, Finland,
Lithuania and Poland could occasionally reach caesium-137 contamination levels of
several thousand Bq/kg 26 .
27. In Germany, the Federal Office for Radiation Protection (BfS) stated in its 2004 annual
report 27 that wild boar remained highly contaminated by Cs-137, especially in the south ofthe country. According to studies carried out in 2004 in the Bavarian forest, soil
contamination levels were still as high as 100,000 Bq/kg. Cs-137 levels in wild boar
muscle were between 60 and 40,000 Bq/kg with an average of 6,800 Bq/kg. This averageis >10 times the 600 Bq/kg EU limit, see table 4.2. Only 15% of the boar samples were
within the EU limit, and 20% exceeded 10,000 Bq/kg. The EU limit was also exceeded inless contaminated areas of Germany, the Pfaelzerwald for instance, which had soil Cs-137
contamination levels of up to several thousand Bq/m2. Recent data from the RhinelandPalatinate Research Institute for Forest Ecology and Forestry has revealed that more than
20% of wild boar samples had Cs-137 levels greater than 600 Bq/kg, with a peak value of
8,200 Bq/kg in 2004 28 .
28. In 2005, the European Commissioner for Transport and Energy, Andris Piebalgs
explained 29 that restrictions will need to be continued for many years.
“… one cannot count on notable changes in the radioactive caesium
contamination of certain products from natural … environments. The
radioactive caesium contamination level of these products is
26

information contained in written answer to Question P-1234/05DE by MEP Rebecca Harms dated April 4,
200527
http://www.bfs.de/bfs/druck/jahresberichte/jb2004_kompl.pdf
28
information contained in written answer to Question P-1234/05DE by MEP Rebecca Harms dated April 4,
2005
29
written answer to Question P-1234/05DE by MEP Rebecca Harms dated April 4, 2005

41

essentially dependent on the half-life of this radionuclide….30 years.
The restrictions on certain foodstuffs from certain Member States
must therefore continue to be maintained for many years to come.”

Continuing High Levels of Contamination
29. Over the next few hundred years, Cs-137 concentrations will gradually decline. Thisdecline will be due to a very small degree from environmental causes (ie Cs-137 entering
deeper levels of some soils), but will mostly will be a result of radioactive decay(IAEA/WHO, 2005b). In practice, this means that Cs-137 contamination levels in wild foods
will remain high for a long time in the future. Indeed, in April 2005, the European Energy
Commissioner, Andris Piebalg admitted as much when he wrote that Cs contamination incertain food products would not decline appreciably in the near future. He stated 30“Due to the experience gained since the Chernobyl accident, the Commission
believes that in the Member State regions significantly affected by the ….accident,
one cannot count on notable changes in the radioactive caesium contamination ofcertain products from natural or near natural environments.”
30. This was repeated in the IAEA/WHO (2005b) report which stated that Cs-137 and Sr90 concentrations and transfer coefficients 31 had decreased only slowly in most plant andanimal foodstuffs during the last decade. This indicated that these radionuclides wereclose to equilibrium in labile and non-labile pools of soil within agricultural ecosystems.
The IAEA/WHO concluded that as far as nuclide concentrations in plant and animal
foodstuffs were concerned:“Given the slow current declines, and the difficulties in quantifying long-term
effective
half-lives for currently available data because of high uncertainties, it is not possible
toconclude that there will be any further substantial decrease over the next decades,
except due to the radioactive decay of 137Cs and 90Sr with half-lives of about 30
years.”
31. Annex 3B (table 3B(i)) sets out official estimates of residual amounts of radioactive
nuclides in the global environment from Chernobyl over the next 50 years until 2056 fromofficial data. However, 2056 is only 70 years after the Chernobyl accident and is anarbitrary choice of date. Scientifically speaking, a more rigorous date would be 2286, ie
300 years after Chernobyl. The reason is that a convention exists among radiation
protection scientists that 10 half lives 32 are necessary to ensure radioactivity levels decline
to an acceptably “safe” level. In the case of Cs-137, this would be about 300 years after
1986, or 2286. Indeed, for this reason, conventional proposals 33 for dealing withradioactive waste usually propose initial storage for 300 years to allow Cs-137 and Sr-90
decay sufficiently to enable its safe handling.
32. Due to the slow radioactive decay of Cs-137, radiation doses from external exposures
to Cs-137 will decline slowly over the next few hundred years. Table 3B(ii) in Annex 3B
30

written answer to a Question P-1234/05DE by MEP Rebecca Harms dated April 4, 2005
parameter describing the velocity of transport of a nuclide usually through soil
32
10 half lives will reduce the original activity by a factor of about 1000 (in fact by 1024)
33
see UK Committee on Radioactive Waste Management draft report (CoRWM, 2006)
31

42

contains estimated future external doses expressed per contamination level (kBq/m2) of
Cs-137. In addition, table 3B(iii) contains estimated future doses from both internal andexternal radiation (1996-2056) to adults living in rural areas contaminated to 555 kBq/m2(15 Ci/km2).

Restricted reporting by UNSCEAR (2000) and IAEA/WHO(2005a, 2005b)
33. Unfortunately, the UNSCEAR (2000) and IAEA/WHO (2005a, 2005b) reports do notdiscuss the comprehensive datasets on European contamination in EC (1998) and do notcite EC (1998) among their references. No explanation is given for this omission.
Moreover, the UNSCEAR (2000) and IAEA/WHO (2005a. 2005b) reports do not discuss
deposition and radiation doses in any country apart from Belarus, Ukraine and Russia.
Indeed, UNSCEAR (2000) stated 34“Information on the contamination levels and radiation doses in other (ie other than
Belarus, Ukraine and Russia) countries will be presented only if it is related toepidemiology studies conducted in those countries.”
This restriction also apparently applies to the 2005 IAEA/WHO reports.
34. It appears that IAEA/WHO decided to focus in their reports only on countries with highdensity depositions of Cs-137 which meant Belarus, Ukraine and Russia. Although heavy
depositions certainly occurred there, the omission of any examination of Chernobyl fallout
in the rest of Europe and the northern hemisphere is questionable. Most of the Cs-137
source term from Chernobyl was deposited outside Belarus, Ukraine and Russia. This wasindicated by the US DoE (1987) and by UNSCEAR (1988) 35 which stated that less thanhalf of the Cs-137 source term was deposited in the then USSR (including Belarus,
Ukraine and Russia), with the majority deposited elsewhere, including the rest of Europe(39%), Asia (8%), Africa (6%), and the Americas (0.6%) 36 . UNSCEAR (2000) 37 also
stated that 40 PBq of Cs-137 was deposited in Belarus, Ukraine and Russia, ie less thanhalf its source term. These data are set out in table 3.6.
Table 3.6 Cs-137 depositions – PBq
ReportBelarus,
UkraineandRussiaRest ofEuropeRest of World(excl Europe
and Belarus,
Ukraine andRussia)~32

US DoE~33~33(Goldman et al, 1987)
UNSCEAR, 1988
29
26
15
EC, 1998
57
28 + 9*UNSCEAR, 2000
40
*for Yugoslavia, Bulgaria and Albania from US DoE data (1986)
shaded cells = estimated by this report34

volume II, Annex J, page 453, paragraph 6
page 342, paragraph 201
36table 24 of UNSCEAR, 1988
37
volume II, Annex J, page 462, paragraph 41
35

43

Total

% in
Belarus,
Ukraineand Russia

~98

~33%

70
85

42%
47%

35. IAEA/WHO’s decision to discount nuclide depositions and radiation exposures in
European countries and the northern hemisphere outside Belarus, Ukraine and Russia isunfortunate. This restriction makes it difficult to estimate the collective dose impact of thedisaster as these depend on Cs-137 depositions, as we shall see in Chapter 5.

44Annex 3A. Chernobyl contamination by area in each country
Table 3A(i) Cs-137 contamination >40 kBq/m2
Country
BelarusAustria
UkraineFinlandSwedenItaly
Slovenia
NorwaySwitzerland
Russia (Europe part)
GreeceRumania
Czech Republic
PolandGermany
United Kingdom
Slovak Republic
TotalsTotal area
1,000 Km2
210
84
600
340
450
280
20
320
41
3,800
130
240
79
310
350
240
49
9,700*

area contaminated >40
kBq/m2 Cs-137: 1,000 Km2
46.1
11
38
19
23.4
8.35
0.61
7.2
0.73
60
1.26
1.2
0.22
0.52
0.32
0.16
0.02
218.95% OF COUNTRY
22%
13
6.3
5.6
5.2
3
3
2.3
1.8
1.6
1
0.5
0.28
0.16
0.09
0.06
0.04
2.3%

data from EC (1998) *includes areas of unlisted countries for which data is not available

Table 3A(ii) Cs-137 contamination 4 - 40 kBq/m2
Country
Moldova
Turkey (Europe part)Slovenia
Switzerland
Austria
Slovak Republic
Rumania
Czech Republic
Lithuania
Croatia
IrelandUkraine
GreeceNorwayGermany
BelarusFinland
Russia (Europe part)
Hungary
United Kingdom
LatviaPolandSwedenEstonia
Italy
FranceLuxembourg
Denmark
Netherlands
Belgium
TotalsTotal area
34
24
20
41
84
49
240
79
65
56
70
600
130
320
350
210
340
3,800
93
240
64
310
450
45
280
550
2.6
45
35
31
9,700*

area contaminated to 4 40 kBq/m2 Cs-137
34
23
19.3
34.7
70
39
187
59
48
40
48
403
66.3
156
153
88
141
1,530
35
81
21
85
119
11
59
55
0.12
0.8
0.64
0.09
3,864

% OF COUNTRY

data from EC (1998) *includes areas of unlisted countries for which data is not available

45

100%
96
96
85
83
80
78
75
74
71
68
67
51
49
44
42
41
40
38
34
33
27
26
24
21
10
5
2
2
0.2
40%

Annex 3B. Future Effects from Chernobyl
Table 3B(i) Residual radionuclides in the global environment from Chernobyl
NuclideHalf-life PBq
PBq
PBq
PBq
years
Released in
Remaining in Remaining in Remaining in
1986
2056
1996
2006
Sr-90
28.8
8
6
4.9
1.5
Cs-134
2.06
48
1.6
0.05
0
Cs-137
30.1
85
68
54
17
Pu-238
87.7
0.03
0.03
0.03
0.02
Pu-23924,400
0.03
0.03
0.03
0.03
Pu-240
6,500
0.044
0.044
0.044
0.04
Pu-241
14.4
5.9
3.6
2.3
0.2
Am-241
432
0.005
0.08
0.12
0.2
source: Dreicer et al, 1996
Greyed column estimated by this report
Am-241 is the decay daughter of Pu-241, and therefore increases in magnitude. Am-241 doses are currently
not thought to exceed doses from other nuclides

Table 3B(ii). External effective doses per Cs- 137 density for residents ofcontaminated areas, expressed over various time periods
Normalized effective dose (μSv per kBq/m2 Cs-137) for rural workers for time period
indicated
Country
1986
1986 - 1995
1996 - 2056
1986 - 2056
Former USSR
13-28
47- 6248
95-110Belarus19
55
Russia15
37
28
65
Ukraine2460
28
88source: table 31, UNSCEAR, 2000

Table 3B(iii). Estimated future doses (1996 - 2056) to adults living in rural areas
contaminated with 555 kBq/m2 Cs-137
Exposure Path
Average Person
Critical GroupmSv
mSv
External Radiation
20
27
Ingestion
1033
Inhalation
0.1
0.3
TOTAL
30
60
source: table VII, Dreicer et al, 1996

46

Chapter 4. Health Effects Resulting from the Chernobyl Accident
Introduction
1.
The immediate impacts of the Chernobyl accident on human health are now wellknown. Acute radiation sickness was diagnosed initially in 237 emergency workers, ofwhom 134 were treated clinically. 28 of them died in 1986 and a further 19 died between
1987 and 2004: more premature deaths may occur.
2.
Less certain are the long term consequences of the accident. Exposure to ionisingradiation can induce cancer in almost every organ in the body. However, the latency
period 38 between exposure to the radiation and appearance of the cancer can be many
years and even several decades. Clearly, therefore, it will be a long time before the full
effects of Chernobyl are known. Indeed, they may never be fully known, as cancer is acommon disease and it may be impossible to distinguish additional cancers from the large
number that would occur anyway.
3.
Many publications list four categories of people affected by the Chernobyl accident.
(a) About 600 emergency workers, who were involved during the first day of theaccident. Of these, 22 workers received whole-body doses of externalradiation greater than 4 Gy and 21 received doses greater than 6 Gy.
(b) About 240,000 cleanup workers or liquidators who, from 1986 to 1989, weresent in to the power station or the zone surrounding it for decontamination
work, sarcophagus construction, and other cleanup operations. Theiraverage dose was 100 mSv.
(c) About 100,000 persons who were evacuated within 2 weeks of the accident
and 16,000 more before the autumn of 1986. Their average dose was 33
mSv.
(d) The approximately 5 million residents of contaminated areas in Belarus,
Ukraine and Russia. Their average dose was 10 mSv. In addition, about
270,000 people were living in highly contaminated areas (more than 555
kBq/m2 Cs-137). Their average dose was 50 mSv.
4.
In addition two other categories exist, which are often not discussed in official
reports and are conspicuously omitted from the IAEA/WHO (2005) reports:(e) Approximately 600 million people who live in the rest of Europe.
(f) Approximately 4 billion people who live in the rest of the northernhemisphere 39
The effects in these last two categories are more diffuse and indeed have been difficult to
detect in epidemiology studies. Nevertheless, they can be estimated using collective
doses. These are considered in Chapter 5.
5.
The health effects resulting from Chernobyl will be discussed under the following
headings:(1) Thyroid cancer(2) Leukaemia
38
39

the latency period is the time interval between the exposure to radiation and the appearance of cancer
little atmospheric mixing occurs between the northern and southern hemispheres47

(3) Solid cancers(4) Non-cancer effects(5) Heritable effects(6) Mental health and psychosocial effects.
6.
There have been a large number of publications in all these categories, many ofwhich have been reviewed in the recent IAEA/WHO (2005a) report and the US BEIR VII(2005) report. Papers continue to appear steadily, together with many anecdotal reports.
Because of the often long delay between exposure to radiation and the appearance of its
effects, lengthy follow up times are necessary before definite conclusions can be drawn.
For example, an important source of information about the induction of cancer by radiation
are the survivors of the Hiroshima and Nagasaki bombings, who have now been followed
up for more than 50 years; it is only relatively recently (Preston et al, 2003) that clear
evidence has emerged of non-cancer effects due to radiation, for example cardiovasculardisease. It is therefore likely that a clear picture of the effects of Chernobyl will not emerge
for many years.
7.
In this report, we shall concentrate on more recent publications, using mainly thosepublished in peer-reviewed journals, always mindful of the many uncertainties involved intrying to unravel the past and the even greater ones in predicting the future. In view of theuse of the words ‘grays’ and ‘sieverts’, a short note on radiation units is set out in Annex 4.

(1) Thyroid Cancer
8.
The first reports of an increase in thyroid cancer in children in the early 1990s(Prisyazhiuk et al, 1991; Kazakov et al, 1992; Baverstock et al, 1992) were greeted withconsiderable scepticism, as it was thought that more cancers were being seen simply
because more were being looked for – a ‘screening effect’. Moreover, the cancers had
appeared only four years or so after the radiation exposure, whereas the latency period of
thyroid cancer was thought to be ten years or more (UNSCEAR, 1988). Another reason for
scepticism was the belief that internal radiation from iodine-131 was not as carcinogenic
as external radiation. For example, there was no evidence of an increased incidence of
thyroid cancer in patients treated with iodine-131 for overactive thyroid (Hennemann,1986).
9.
However, further work (Astakhova et al, 1998; Jacob et al, 2000; Heidenreich et al,1999) confirmed that there was indeed a dramatic increase in childhood thyroid cancer,
and there is now overwhelming evidence that this is related to exposure to iodine-131 andpossibly to other isotopes of iodine with shorter half-lives. Between 1990 and 1997,
childhood thyroid cancer increased by a factor of about 30 in the most heavily
contaminated areas (Tawn, 2001). The short latency period, 3-4 years, may well havebeen influenced by the promptness with which screening of school children occurred inareas of high fallout (Astakhova, 1998).
10.
Up to 2005, there have been about 4,000 cases of thyroid cancer in Belarus,
Ukraine and Russia (Cardis, 2005a) in those who were under 18 at the time of theaccident; 3,000 of these were under 15. Annual incidence rates up to 2002 in Belarus andUkraine are shown in figure 4.1.

48

Figure 4.1. Annual thyroid cancer incidence rates per 100,000 in those who werechildren and adolescents in 1986

source: Jacob et al (2005)

Figure 4.2 Annual incidence of thyroid cancer in Belarus
12

Incidence per 100 000 in Belarus

11.3
Adolescents

9.5

10Children (0 -14)

9.7

Adolescents (15 - 18)
Adults (19 - 34)

8

C ases per 100 000

Young adults

6.6

6

5.7

5.6

6.9

5.7

4.9
4

4

3.5

3.4
2.9
2.3

2

1.2

1.4

0.8
0.3

0.1

0.3

0.2

0.4

3.8
2.9

3.2

4.2
3.8
3
2.1

1.9

3.1

2.5

2.6
2.6

1.4

1,0

3.4

1.7 Children
0.7

0.8

0

0
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

source: reproduced from lecture presentation by E Cardis to IAEA/WHO Conference Chernobyl: Looking
Back to Go Forward. September 2005. Original data from Dr Yuri Demidchik.

49

11.
As can be seen in figure 4.2 for Belarus, the peak incidence in the 0-14 age group
was in 1995, and for the 15-18 age group, the peak was in 2000. In addition, the incidenceof thyroid cancer among adults is rising. (Cardis, 2005a).
12.

Several important points emerge from the many papers published on this topic:(i) the younger the person exposed, the greater the subsequent risk of developing
thyroid cancer. For a given intake of radioiodine, children will receive the highest
thyroid dose, as their thyroid glands are smaller and still growing(ii) there is no clear evidence that exposure to iodine-131 in utero has caused thyroid
cancer, but the relevant studies have limited statistical power 40(iii) the risk of thyroid cancer is greater when there is iodine deficiency(iv)dietary iodine supplements can reduce the risk, even if administered some time after
the exposure to radiation
13.
Before the Chernobyl accident, the principal source of information about radiationinduced thyroid cancer in children was several studies in which children had been exposed
to external X-rays. A survey of these studies (Ron et al, 1995) showed that the thyroid
cancer risk was still increased more than 40 years after the initial exposure. For children
aged under 15 at the time of exposure there was a linear relationship between risk anddose down to 100 mGy. The best estimate of the excess relative risk per gray (ERR/Gy) 41
was 7.7 (95% confidence intervals 42 2.1 to 28.7). This is consistent with the estimate by
Cardis (2005b) in which the ERR/Gy varied between 4.5 to 7.4, depending on the model
used (95% confidence intervals 1.0 to 16.3). More recently, Jacob et al (2005, 2006) fromtheir study of thyroid cancer risk in Ukraine and Belarus, also estimated ERR/Gy values
close to those observed by Ron et al (1995).
How many more thyroid cancers can we expect?
14.
Because we do not know at this stage how the risk will change in the future, there
are considerable uncertainties in estimating the total number of thyroid cancers that arelikely to result from Chernobyl. In the words of the IAEA/WHO report [ pp 39-40]:‘although thyroid cancer risk is continuing at a high level, and there is no reason
to expect a decrease in the next 15 or more years, at the present time thefollow-up of Chernobyl-exposed children is too short to determine the long-termrisks’.
15.
Some attempt at prediction can be made by assuming that the change in risk in the
future will be similar to that seen with external radiation. Jacob et al (2000) estimate thatfor Belarus, starting in 1997, 15,000 thyroid cancers will occur with an uncertainty range of
5,000-45,000. The UNDP (2002) says that ‘according to conservative estimates, thenumbers of thyroid cancers are likely to rise to 8,000 to 10,000’. Cardis et al (1999) predict40

The power of a study is the probability of detecting a given difference. Even if a difference is real, if it issmall and the size of the groups we are comparing is small, there will only be a very small probability ofdetecting the difference.
41
Relative risk (or Odds Ratio) is the risk of contracting a particular disease for an exposed individual,
divided by the risk of contracting that disease in an unexposed individual. So if the relative risk (RR) of
thyroid cancer is 8.7 per gray (8.7/Gy), this means that a radiation dose of 1 gray (Gy) to the thyroid will
make that individual 8.7 times more likely to contract thyroid cancer. Excess relative risk (ERR) = relative risk
(RR) – 1; so a relative risk of 8.7 corresponds to an excess relative risk of 7.7.
42
If we were to carry out a large number of similar studies, the true value of the risk would lie within the 95%
confidence interval in 95% of the studies. So essentially the confidence interval gives a range of values withwhich the data are compatible.

50

the lifetime number of thyroid cancers that would develop among children in Belarus aged
less than 5 years at the time of the accident. Depending on the risk projection used, theirestimates range between 18,000 and 66,000 excess thyroid cancers. The lower estimate
assumes a constant relative risk for 40 years after exposure; the higher assumes aconstant relative risk over the whole of life.
16.
A very recent study (Imaizumi et al, 2006) of thyroid cancer incidence in thesurvivors of the Japanese atomic bombs found that a significant dose-response
relationship still existed nearly 60 years after exposure, and that the effects weresignificantly greater in those exposed at younger ages. This suggests that of the above
two risk projections, the latter may be more likely with a consequently larger number ofthyroid cancers.
Thyroid cancer in adults
17.
Although there is now good evidence from a number of studies that the increased
incidence of thyroid cancer in children is related to Chernobyl, the association is less clear
in adults. Table 4.1 contains a review by Moysich et al (2002) of studies of adult thyroid
cancer incidences.
Table 4.1 Studies of adult thyroid cancer incidence
Reference Country Kind
Period Comparison
Type

Exposurevariables

Findings

Mettler et al,
1992

Ukrainedescriptive

1990

Prevalence of
thyroid nodules

high and low
contam villages

Prisyazhniuk
et al, 1995
Inskip et al,
1997

Ukrainedescriptive
liquidator
cohortIncidence rates
over time
Prevalence of
thyroid nodules-

Estonia

19801993
1995

Ivanov et al
1997a,
1997b

Russiaincidence,mortality

19861990

Incidence incohort vs
population

Assigned ext
doses during
clean-up
exposures

Ivanov et al
1997cRussiaDescriptive
incidence

19811995

Incidence rates
over time

Rahu et al,
1997

Estonia

Liquidator
cohort19861993

Ivanov et al,
1999

Russiadescriptive
incidence

19821995

Incidence incohort vs
population
Incidence rates
over time

No differ inprevalence of
thyroid
nodulesNo sigincrease
No differ inprevalence of
thyroid
nodules>incidence inliquidators
SIR=670 95%
CI=420-1030
No sigincrease incontam vsnon-contam
areas
No excessthyroid cancer
incidence>nos ofthyroidcancers incontam areas

questionnaire;measurements

questionnaire
Contam vs noncontam areas

source: Moyisch et al, 2002

18.
One study which has shown a significant effect examined data on 168,000 cleanup
workers from Russia (Ivanov et al, 1997d). The ERR/Gy for thyroid cancer was found to be
5.31 (95% CI: 0.04, 10.58) which is consistent with the value of 7.7 estimated by Cardis(see paragraph 13 above).

51

Thyroid cancers outside Belarus, Ukraine and Russia
19.
In total, about 2,000 PBq of iodine-131 was released in the Chernobyl accident, andmore than half of this was deposited outside Belarus, Ukraine and Russia. One might
therefore expect some thyroid cancers to occur elsewhere, at least in the morecontaminated countries. The 2005 IAEA/WHO reports did not consider this, except to referto the Sali review (Sali et al, 1996). Although this concluded that no increase in thyroid
cancer among children was observed, it also pointed out that “no study focussed
specifically on childhood thyroid cancer, since the disease is so rare and a small increase
could have gone undetected in these studies”. (emphasis added)20.
Since 1996, there have in fact been a number of reports of possible increases inthyroid cancer in other European countries. Murbeth et al (2004) reported an increase in
the Czech Republic. They found the incidence of thyroid cancer had increased by 2.6%
per year (95%-CI: 1.2 - 4.1, p=0.0003) in all age categories after 1990. The Czech
Republic received a moderate amount of radioactive fallout: as shown in Annex 3A, withthree quarters of its surface area slightly contaminated (ie to a level greater than 4
kBq/m2). The authors came to the reasonable conclusion that “one should look carefully atcollective dose and at the groups of persons low in individual organ dose but high in
number”. This recommendation has not been followed up by the IAEA/WHO (2005) reports
which, as we stated earlier, fail to examine health effects in Europe outside Belarus,
Ukraine and Russia.
21.
Cotterill et al (2001) reported an increasing incidence of thyroid cancer in the Northof England, particularly Cumbria one of the two areas in the UK receiving the heaviest
fallout. They pointed out that iodine-131 concentrations in rainwater were as high as 784
Bq/litre and in goat’s milk as high as 1,040 Bq/litre. These concentrations are higher thanthe EC’s Community Food Intervention Levels shown in table 4.2.
Table 4.2

Community Food Intervention Levels (Bq/kg)
Baby Foods

Dairy Produce

Other Foods

Sr-90

75

125

750

I-131

150

500

2,000

Sum ofCs-137 and Cs-134

370

370

600

1

20

80

Plutonium-239

source: European Council Regulations (Euratom) Nos 3955/87, 944/89, 2218/89, 4003/89, 737/90 and
1609/2000

22.
Shortly after the accident, Baverstock (1986) estimated that young children might
receive thyroid doses between 10 and 20 mGy resulting in a 10-20% greater risk of thyroid
cancer. Thyroid doses of 20 mGy are not negligible; the study of childhood thyroid cancer
in Belarus and Russia by Jacob et al (1999) points out that the risk of thyroid cancer waselevated even in the lowest dose group, which received an average dose of only 50 mGy(range 25 to 98 mGy).
23.
Although Cotterill et al state that factors such as earlier detection of tumours may
have contributed to the increasing incidence, their conclusion is that ‘further collaborativeinternational studies are needed to investigate changes in the incidence of thyroid cancer
in children and young adults’. To the best of our knowledge, this has not been done.
24.
A contrary view was taken by Colonna et al (2002), who examined the incidence
data for thyroid cancer from eight French cancer registries over the period 1978-1997.
Their analysis showed an increase in thyroid cancer but not a recent one, which therefore52

could not be due to Chernobyl (the authors suggest that it could be a screening effect).
Obviously there are many uncertainties here, and it is clear that further work is necessary
to establish the extent of thyroid cancer in all countries, not just Belarus, Ukraine andRussia, which received significant depositions of iodine-131.

(2) Leukaemia
25.
Leukaemia is a well-documented effect of ionising radiation, with a relatively shortlatency period of between 2 and 5 years.
Leukaemia in cleanup workers
26.
Fairly clear evidence indicates that leukaemia incidence increased in the clean-up
workers: there was a two-fold increase in the most highly exposed group, although dose
estimates are uncertain. More precise estimates are expected in the near future from ongoing studies (Cardis 2005a). Ivanov et al (1997d) in their study of Russian cleanup
workers suggest that one of every two leukaemias diagnosed in emergency workers today
could be radiation-induced. They also point out that the incidence of leukaemia in the
Russian cleanup workers is consistent with the incidence predicted from the atomic bomb
survivors - see figure 4.3.
Figure 4.3 Anticipated and Observed Standardised Incidence Ratios of Leukaemia in
Russian Clean-up Workers (bars give 95% confidence intervals)

source: reproduced from Ivanov et al (1997d)

Leukaemia in residents of contaminated areas
27.
Noshchenko et al (2001) have suggested that there was an increased risk ofleukaemia and acute leukaemia among children who were born in 1986 and were resident
in radioactively contaminated territories. They suggested this increased risk may be
associated with exposure to radiation. A case-control study by Noshchenko et al (2002)
examined residents aged 0-20 at the time of the Chernobyl accident in the most53

radioactively contaminated territories of the Ukraine. They estimated the risk of radiationinduced acute leukaemia for the period 1987-1997. The mean value of the estimatedaccumulated dose to the bone marrow was 4.5 mSv, and the maximum was 101 mSv. A
statistically significant increased risk of leukaemia was found among males whose
estimated radiation exposure was higher than 10 mSv. This association was statisticallysignificant for acute leukaemia cases that occurred in the period 1993-1997, particularly foracute lymphoblastic leukaemia. A similar association was found for acute myeloid
leukaemia, diagnosed in the period 1987-1992.
Leukaemia in other European countries
28.
A number of studies appear to show an increased rate of childhood leukaemia as aresult of the Chernobyl fallout in parts of Europe. These were recently reviewed by the UK
Government’s Committee Examining Radiation Risks of Internal Emitters (CERRIE, 2004)
which reported increases in infant leukaemia in West Germany, Greece and Belarus. The
IAEA/WHO (2005a) report on health effects downplayed the importance of these studies,mainly because in their view the studies did not show a clear link between the incidence ofleukaemia and the degree of contamination (ie with dose).
29.
However, given the large uncertainties in estimating doses from the degree ofcontamination, the absence of a strong association between leukaemia incidence andcontamination does not rule out a radiation effect. The IAEA/WHO report (2005a) itself lists
the gaps in our knowledge of doses, including:• “There is a lack of information on intercomparison between the various dosimetricmethods, though studies are currently in progress.
• Doses to be received in the future can only be predicted.
• The reliability of interviews used to assess factors which affect an individual’s dose
has not been definitively assessed.
• Internal doses resulting from intakes of Sr-90 and of Pu-239 have received limited
attention.
• Methods to estimate doses received by those exposed in utero need further work on
the dosimetric methodology and validity of such dose estimates.
• The conversion of effective doses into absorbed organ-specific doses such as bonemarrow dose needs to be delineated.”30.
In 1988, the European Childhood Leukaemia-Lymphoma Incidence Study (ECLIS)
was set up by IARC to investigate possible changes in incidence rates of childhood
leukaemia and lymphoma in Europe following the Chernobyl accident (Parkin, 1993). Data
were drawn from 36 cancer registries in 23 European countries. The study’s follow-up
report for the period 1980-1991 (Parkin, 1996) found a small increase in leukaemia
incidence in Europe as a whole (13 cases observed against 7.3 expected in the highest
dose category), but there did not appear to be any association between the overall risk ofleukaemia in the period 1987-91 and the estimated doses received. However, they added“at this stage of follow-up, the study has low power to detect a trend in risk with dose.”
31.
Regarding the possible consequences of radiation doses received in utero, Parkin
et al (1996) stated that they found'”no suggestion of an increase in risk of childhood leukaemia for children exposed inutero, even among the 1987 birth cohort in Belarus, some of whom would havereceived in utero exposures in excess of 1 mSv”.
However, both BEIR VII (2005) and the IAEA/WHO(2005a) suggested that there may well
be an effect:
54

”Focusing on the risk of leukaemia by age of diagnosis (six months intervals)
in relation to the estimated dose from the Chernobyl fallout received in utero,preliminary results suggest a small increase in risk in infant leukaemia andleukaemia diagnosed between 24-29 months.” (IAEA/WHO, 2005a)
This issue remains unresolved. We recommend in paragraph 33 below that funding bemade available to IARC to clarify this matter.
32.
The 1996 ECLIS paper was re-evaluated by Hoffmann (2002) who stated thatleukaemia incidence in the birth cohort of 1987 was increased in the two highest exposure
categories. He concluded that Chernobyl fallout could well have caused a small, but
significant, excess of childhood leukaemia cases in Europe, possibly due to the inductionof chromosome aberrations in early pregnancy. He went on to say that “…if indeed
Chernobyl fallout has caused childhood leukaemia cases in Europe, we would also expect
an increased incidence for other childhood cancers and excess malignancies in adults aswell as non-malignant diseases of all ages. Neither of these endpoints has as yet beensystematically studied.” [emphasis added]
33.
Although most of the data from the ECLIS study has now been collected andstudied, the final results of the study have not been published. This is unfortunate: werecommend that funds be made available to permit the IARC to finish and publish its
study, and, while doing so, to resolve the evidence on the possible consequences ofradiation doses received in utero.

(3) Other solid cancers
Cancers in cleanup workers
34.
Using data for cleanup workers from the Belarus National Cancer Registry,
Okeanov et al (2004) compared baseline incidence rates for overall cancer and various
cancers between 1976-85 with those between 1990-2000. An average 40% increase incancer incidence was observed in all regions with the most pronounced increase in themost contaminated region. The 56% increase between the two time periods was
statistically significant. In 1997-2000, male liquidators had statistically significantly raisedrisk of cancers of all sites, colon, lung and bladder cancer compared with adults in theleast contaminated region - as shown in table 4.2. Based on the estimated collective doseto all cleanup workers in Belarus, Ukraine and Russian (see table 5.1), we might expect
around 1,000 – 2,000 excess deaths from solid cancers due to Chernobyl-related radiation
exposures in this group.
Table 4.2 Relative risk (RR) in cancer incidence (truncated age-standardised rate forages 20-85 per 100,000 population) in Belarus liquidators 1997-2000, compared with
control adults in least contaminated area (Vitebsk)
CancerAll sites
Breast (female)
Lung
StomachColon
RectumKidneyBladder

Incidence incontrols
373.3
58.6
52.4
41.7
17.0
19.0
14.8
10.9

Incidence inliquidators
449.3
61.3
67.3
44.9
22.3
18.4
17.9
17.0

source: Okeanov et al (2004)*statistically significant differences

55

RR
1.20*
1.05
1.28*
1.08
1.31*
0.97
1.21
1.55*

95% confidence
intervals
1.14 – 1.27
0.81 – 1.35
1.13 – 1.46
0.92 – 1.26
1.03 – 1.67
0.77 – 1.23
0.97 – 1.50
1.21 – 1.99

Breast cancer in Belarus, Ukraine and Russia
35.
Breast cancer is particularly important, because the risk of breast cancer among
women exposed in childhood and adolescence is the next highest risk after leukaemia andthyroid cancer risks, as regards radiation-induced cancer (IAEA/WHO, 1995). Moreover,iodine (and therefore radioiodine) is concentrated in the breast and salivary glands inaddition to the thyroid.
36.
The IAEA/WHO report (2005a) acknowledges preliminary evidence of an increasein the incidence of pre-menopausal breast cancer among women exposed at ages lower
than 45 years. This has been confirmed in a soon-to-be published study by Pukkala et al(in press) which describes trends in the incidence of breast cancer in Belarus and Ukraine.
Their results suggest that women who reside in the most contaminated districts have an
increased risk of breast cancer compared with women in less contaminated areas. Doses
were estimated using average whole body doses accumulated since the accident, bothfrom external exposure and the ingestion of long-lived radionuclides. Those living in themost contaminated districts had an average cumulative dose of 40 mSv or more. In these
districts, a significant two-fold increase in risk was observed during the period 1997-2001
compared with the least contaminated districts (the RR in Belarus was 2.24, 95% CI 1.513.32 and in Ukraine the RR was 1.78, 95% CI 1.08-2.93). The increase, though based ona relatively small number of cases, appeared approximately 10 years after the accident; it
was highest among women who were younger at the time of exposure, and was observed
for both localised and metastasised cancers. The authors conclude that “it is unlikely that
this excess could be entirely due to increased diagnostic activity in these areas.”
Bladder and Kidney Cancer
37.
Romanenko et al (2003) have reported that the incidence of urinary bladder cancer
in the Ukraine has increased from 26.2 to 43.3 per 100,000 person-years between 1986
and 2001. Romanenko et al (2000) have also reported that the incidence of cancer of thekidney has increased from 4.7 to 7.5 per 100,000 person years.
Cancer in other European countries
38.
Sali et al (1996) did not show any significant increases in cancer incidence in other
European countries, but they pointed out the lack of statistical power and the fact that the
study only covered the first nine years after the accident. Apart from leukaemia andperhaps thyroid cancer in children, there is evidence that the minimum latency period formost solid cancers is at least 10 years, so positive results would not have been expected
in 1996. According to Tondel et al (2004), there has been an increase in the total incidenceof cancer in northern Sweden; they estimate the excess relative risk to be 0.11 per 100
kBq/m2 of Cs-137 (95% confidence intervals 0.03 to 0.20) corresponding to a relative riskof 1.21 for the most contaminated areas.

(4) Non-cancer effects
39.
Over the last twenty years, a large number of health effects have been attributed to
the Chernobyl accident, including reduced fertility, increased incidence of stillbirths, birthdefects, Down’s syndrome and infant mortality. Evaluation of the many reports and claims
is extremely difficult, given the prevailing context of political changes, adverse economic
circumstances and the apparent deterioration of many health and well-being indices. The
following problems are associated with many of these reports of adverse health effects:• diagnostic criteria often differ• insufficient control groups exist
56• the studies have low power, and• confounding factors are present, notably smoking and alcohol
In response to this, the IAEA/WHO has stated “there remains an overall need to design
future studies with extreme care in order to be able to obtain useful, unbiased and nonconfusing information” (IAEA/WHO, 2005a).
40.
Many commentators have highlighted the marked general deterioration in healthindicators in Belarus, Ukraine and Russia. To give a graphic illustration - over the last 15
years, the average lifespan for a male in Russia has decreased from over 70 to about 61
years and in the Ukraine from 67 to 61 years: in western Europe, the average male life
span is about 75. The reasons for the considerable declines in health indicators in Belarus,
Ukraine and Russia are complex and due to a number of interrelated factors as describedin the UNDP (2002) report. Without access to government data, it is very difficult to assess
whether continuing exposures to low residual levels of radioactivity is a factor in thegeneral deterioration in health in Belarus, Ukraine and Russia. However it is noted that the
declines have occurred in all areas of Belarus, Ukraine and Russia and not merely thoseareas affected by radioactive fallout.
41.
Two non-cancer effects that are now reasonably well-documented and for which
there is clear evidence of a Chernobyl connection are cataract induction andcardiovascular disease.
(a) Cataract Induction
42.
Cataract-opacity (cloudiness of the eye lens) is an effect of exposure to radiation.
The latency period seems to be inversely proportional to dose, so long follow-up times arenecessary for small exposures. As with childhood thyroid cancer, this is another area
where previous thinking on radiation’s effects is being revised as a result of Chernobyl. In
1990, the ICRP had stated that the threshold for opacities sufficient to cause impairment ofvision was in the range 2 to 10 Gy (ICRP, 1991). In contrast, IAEA/WHO now states that “afocus of the Chernobyl eye studies is a hypothesis that radiation cataract/opacifications
detectable by an experienced examiner may occur at doses lower than previously thought.
These studies do not appear to support the older classic literature on radiation cataracts,
which concluded that a relatively high threshold (e.g. 2 Gy) must be exceeded forcataracts to appear after ionising radiation exposure.” (IAEA/WHO, 2005a) Studies of thecleanup workers suggest that cataracts might be caused by doses as low as 0.25 Gy.
Lens changes related to radiation have been observed in children and young people aged
between 5 and 17 living in the area around Chernobyl (Day et al, 1995).
(b) Cardiovascular diseases
43.
Here again an ICRP pronouncement has been contradicted by new evidence. ICRP
Publication 60 had stated (para 62, page 16) “It seems that no stochastic effects in the
exposed individual other than cancer (and benign tumours in some organs) are induced byradiation. In particular, any life-shortening found in exposed human populations and inexperimental animals after low doses has been shown to be due to excess radiationinduced cancer mortality” (ICRP, 1991). But the most recent follow-up of the Hiroshima
and Nagasaki survivors shows clearly that there is a linear dose-response relationship for
myocardial infarction among survivors exposed at less than 40 years of age (Preston et al,2003). In fact, statistically-significant radiation effects are seen for• heart disease (ERR/Sv = 0.17, 95% CI 0.08 to 0.26)• stroke (ERR/Sv = 0.12, 95% CI 0.02 to 0.22)• respiratory disease (ERR/Sv = 0.18, 95% CI 0.06 to 0.32) and57

• digestive disease (ERR/Sv = 0.15, 95% CI 0.00 to 0.32)
44.
A large study of Chernobyl emergency workers (Ivanov et al, 2000) showed asignificantly increased risk of cardiovascular disease. The ERR/Sv was 0.54 (95% CI 0.18
– 0.91), three times higher than the value from the atomic bomb survivors, although the
95% confidence intervals overlap, meaning that the two ERR values could be consistent
with one another.

(5) Heritable effects
45.
It is well known that radiation can damage genes and chromosomes. The
relationship between genetic changes and the development of future disease is complex
however and the relevance of such damage to future risk is often unclear. We might
expect that parental exposure to radiation would produce an increased incidence ofinherited disease in the children of exposed individuals. Nevertheless no evidence ofincreased genetic damage has yet appeared in the children of the Hiroshima andNagasaki survivors. This could be because the samples are not large enough to show astatistically significant effect - in other words, there is insufficient statistical power. As aresult, estimates of genetic risk in humans are usually based on data from animal
experiments.
46.
On the other hand, a number of recent studies have examined genetic damage inthose exposed to radiation from the Chernobyl accident. Some have examined changes inminisatellites, which are sequences of repeated DNA particularly prone to mutations.
These are often used as markers for measuring the effects of low doses of radiation,although whether such mutations affect the future health of those exposed is unknown.
Potentially important are changes in the DNA of eggs and sperm (collectively referred toas germline DNA) as this DNA becomes incorporated into every cell in the children of the
exposed individuals.
47.
Studies of the population of Mogilev province in Belarus have suggested a twofold
increase in the germline minisatellite mutation rate (Dubrova et al, 1996; Dubrova et al,1997). Analysis of another cohort of irradiated families from Ukraine confirmed thesefindings and showed that in both groups the observed increase was attributed to mutationinduction in exposed fathers but not mothers (Dubrova et al, 2002). In contrast to the
Belarus study which used non-irradiated families from the United Kingdom as the control
group, the Ukraine study used fully-matched controls and exposed groups of families.
Conversely, Livshits et al (2001) and Kiuru et al (2003) found exposure to radiation had no
significant effect on minisatellite mutations in the children of Chernobyl cleanup workers
compared with the children of control families from the Ukraine. However, Livshits et al did
find that the subgroup of children conceived either while their fathers were working at
Chernobyl or up to two months later had a higher frequency of mutations than children
conceived at least four months after their fathers had stopped working at the site. Slebos
et al (2004) also examined DNA from lymphocytes in the children of cleanup workers andfound no significant difference in mutation frequency between children conceived before
their father’s exposure and those conceived after. They pointed out, however, that theirsample size was small giving the study low the statistical power.
48.
Clearly this is a matter requiring further studies over longer time periods. Futurestudies may indicate that this could be another area where established views about
radiation’s effects may need to be revised.

58

(6) Mental Health and Psychosocial effects
49.
The Chernobyl accident has had profound and far-reaching psychosocial effects.
The origins of these effects are complex, and are related to several factors, including:• Anxiety about the possible effects of radiation, often leading to extreme
pessimism, depression, apathy and fatalism• Changes in lifestyle, particularly diet, alcohol and tobacco• Feelings of being a victim, leading to a sense of social exclusion and an
expectation of external support, including financial help and special medical
treatment• Stress associated with evacuation and resettlement (see UNDP, 2002)
50.
In a short report such as this it is difficult, if not impossible, to do justice to the scaleof these problems. Chapter 15 of the IAEA/WHO report (2005a) which describes themental, psychological and central nervous system effects of Chernobyl states:“The mental health impact of Chernobyl is the largest public health problem caused by the accident
to date. The magnitude and scope of the disaster, the size of the affected population, and the longterm consequences make it, by far, the worst industrial disaster on record. Chernobyl unleashed acomplex web of events and long-term difficulties, such as massive relocation, loss of economic
stability, and long-term threats to health in current and, possibly, future generations, that resulted in
an increased sense of anomie and diminished sense of physical and emotional balance. It may
never be possible to disentangle the multiple Chernobyl stressors from those following in its wake,
including the dissolution of the Soviet Union. However, the high levels of anxiety and medically
unexplained physical symptoms continue to this day. The studies also reveal the importance ofunderstanding the role of perceived threat to health in epidemiology studies of health effects.”“What the Chernobyl disaster has clearly demonstrated is the central role of information and how it iscommunicated in the aftermath of radiation or toxicological incidents. Nuclear activities in Westerncountries have also tended to be shrouded in secrecy. The Chernobyl experience has raised theawareness among disaster planners and health authorities that the dissemination of timely andaccurate information by trusted leaders is of the greatest importance.”

59Annex 4. Radiation Dose Units
A measure of the effect of radiation is the amount of energy it deposits in unit mass ofbody tissue. This quantity is called the absorbed dose. The unit of absorbed dose is thegray (Gy). One gray is equal to the energy deposition of 1 joule in 1 kilogram of tissue.
The biological effects of alpha particles and neutrons (high LET 43 radiation) are in generalmuch greater than the effects of beta particles and gamma rays (low LET radiation) of thesame energy. The Radiation Weighting Factor wR is introduced to take account of thedifferent biological effectiveness of alpha and beta particles, neutrons, X and gamma rays.
The quantity equivalent dose is then defined as: equivalent dose = absorbed dose x wR
The unit of equivalent dose is the sievert (Sv).
In studies of low dose radiation, the sievert is too large a unit and doses are usually given
in millisieverts (mSv) where 1 Sv = 1,000 mSv (see below)
For low LET radiation, wR = 1, so grays and sieverts will be numerically equivalent.
However, for alpha particles wR = 20, so an absorbed dose of 1 mGy produced by alphaparticles will have an equivalent dose of 20 mSv.

Systeme Internationale Nomenclature (commonly used units)
E = exa
P = peta
T = teraG = giga (one billion)
M = mega (one million)
K = kilo (one thousand)= 1018= 1015= 1012
= 109
= 106
= 103

c = centi (one hundredth)m = milli (one thousandth)µ = micro (one millionth)n = nano (one billionth)p = pico (one trillionth)= 10-2= 10-3= 10-6= 10-9= 10-12

Examples are
mSv = millisievert (one thousandth of a sievert)µSv = microsievert (one millionth of a sievert)
nSv = nanosievert (one billionth of a sievert)

43= 10-3 Sv= 10-6 Sv= 10-9 Sv

LET= linear energy transfer, ie the energy transferred per unit length of the radiation track60

Chapter 5. Collective Doses
Introduction
1. Radiation exposures are mainly measured in two ways: individual doses and collective
doses. As their names suggest, individual doses are per person: collective doses are thesum of individual doses to all exposed persons in a defined area, for example a workforce,a country, a region, or indeed the world. This may appear straightforward, but within many
governments, the nuclear industry and, to a lesser extent, within radiation protection
circles, there is a noticeable reluctance to use and discuss collective doses. For example,
although legal limits exist in most countries for individual doses, to our knowledge none
exists for collective doses. This means that few, if any, legal or administrative sanctions
exist against high collective doses. Also, of the ICRP’s three main principles of justification,
optimisation and limitation (of radiation exposures), only the first two refer to collective
dose 44 .
2. This reluctance is partly due to the uncertainties involved, and partly due to the fact thatfrom a given collective dose one can estimate the numbers of future cancer deaths, whichsome radiation protection authorities do not wish to emphasise. Despite this reluctance,
scientifically speaking a good case exists for using collective doses. This arises fromlinear-no-threshold (LNT) hypothesis for radiation’s effects. This theory predicts thatradiation’s effects continue to exist even at very low doses, declining linearly with dose
without a threshold. That is, there is no dose below which effects do not occur. A corollaryof the LNT is that it is scientifically correct to estimate collective doses even whereindividual doses are very low, for example below background radiation doses. This isdiscussed in more detail in Annex 6A. The recent reports by the IAEA/WHO (2005a,
2005b) and UNSCEAR (2000) give short shrift to collective doses particularly when
individual doses are low.
3. This chapter discusses collective dose estimates made by official studies for Belarus,
Ukraine and Russia; the rest of Europe; the rest of the world; and total global doses. We
shall also make an estimate for collective doses from very long-lived nuclides including C14 and I-129.
4. Collective doses are estimated by assessing the average doses to populations
exposed to radiation. Such dose assessments take into account
•
•
•
•
•
•

deposition densities of Cs-137 and other nuclides
population numbers in affected areas
estimates of average external dose from deposited nuclides
estimates of average internal dose from ingestion and inhalation of nuclides
habits and diets of affected populations (in some reports), andconversion factors from Gy to Sv (from organ doses to whole body doses)

5. It is necessary to identify clearly the time periods over which a collective dose isestimated. For example, the exposed populations in Belarus, Ukraine and Russia received
approximately one third of their collective dose in the first year after Chernobyl.
Approximately another third was received in the next nine years (ie 1987 to 1996), and44

in the 1980s and 1990s, the ICRP (without informing the public) debated the issue of collective dose, but
was unable to agree on recommending a limit.

61

about another third will be received between 1997 and 2056, ie 70 years after Chernobyl.
Unfortunately, time periods are missing, glossed over or left to footnotes in some official
reports. In other reports, no consistency exists: one year, 10 years, 20 years and 70 years
are variously used. This is unscientific as it makes proper comparisons very difficult and isindicative of the poor attitude towards collective dose in official reports.
6. No greater time periods than 70 years are used, to our knowledge. This limitation to 70
years (the so-called lifetime period) is illogical as collective doses will continue to arise
from Cs-137 exposures well into the next century and beyond. A 300 year period (ie 10
halflives of Cs-137) would be more relevant, but such a period does not appear in theliterature on Chernobyl we have examined.
A. Collective Dose Estimates for Belarus, Ukraine and Russia
7. The report prepared by Cardis et al (1996) for the IAEA/WHO Conference in 1996 on
the 10th anniversary of Chernobyl contained the following table reproduced below
Table 5.1 Estimates of Collective Effective Doses to 1996 in Belarus, Ukraine andRussia by Cardis et al, 1996
Population
NumberCollective effectivedose(a) (person Sv)
Liquidators (1986-1987)
200,000
20,000Evacuees
135,000
1,600
Persons living in contaminated areas
270,000
10,000 - 20,000
Cs-137 > 555 kBq/m2
Persons living in contaminated areas
6,800,000
35,000 -100,000
Cs-137 > 37-555 kBq/m2
Total
7,405,000
67,000 - 140,000(a) These doses are for 1986-1995; over the longer term (1996-2056), the collective dose will
increase by approximately 50% (footnote in original)

In view of the Cardis et al’ advice to increase the collective dose by 50%, we do this below
Total
7,405,000
100,000 – 210,000
source: Cardis et al (1996)

8. Table 5.2 compares estimates of collective doses in Belarus, Ukraine and Russia
reports by national and international agencies and others including Cardis et al (1996).
Table 5.2 Estimated Collective Doses in Belarus, Ukraine and Russia
StudyCollective effective
Exposure period
dose - Person Sv
US DoE (Anspaugh et al, 1988)
326,000*
50 years
UNSCEAR 1988 (Bennett 1995,1996)
216,000
to 2056
Cardis et al (1996) table 5.1 using footnote
100,000 - 210,000
to 2056
Malko (1998a)
165,000
lifetime
Ukraine Government (2001)
58,000 (Ukraine)
2056
IAEA/WHO (2005b)
55,0002006* (person Gy)
9. The IAEA/WHO’s collective dose assessment of 55,000 person Sv is the lowest
estimate by some margin: it is considerably lower than the estimates by Cardis et alpresented to the IAEA/WHO 1996 conference and shown in table 5.1. It is lower than the62Ukrainian Government’s estimate for Ukraine alone. Note that the IAEA/WHO estimate is
only to 2006 and they make no estimate for future doses, unlike the other studies. The
studies by Cardis et al (1996), Malko (1998) and Bennett (1995, 1996) werecomprehensive using the latest available data. It is difficult to understand the IAEA/WHO’s
decision not to include these estimates in their report to the 2005 Conference. The studies
by Bennett in particular are relevant: his methodology is set out in Annex 5A.
B. Collective Doses in the Rest of Europe
10. Estimates for collective doses in the rest of Europe are set out in table 5.3. Moredetailed country by country estimates are contained in Annex 5B.
Table 5.3 Collective dose estimates for Europe (excluding Belarus, Ukraine andRussia)Study
Collective Dose
Periodperson Sv
US DoE (Anspaugh et al,
580,000
50 years
1988)
UNSCEAR, 1988
318,000
to 2056(Bennett 1995,1996)
OECD/NEA, 1996
68,000in first year
11. The OECD/NEA estimate is only for the first year (ie 1986 to 1987) in which only about
30% of the collective dose would have been received. To obtain a proper estimate to2056, we need to increase this value by a factor of about 3.4:.
OECD/NEA, 1996
~230,000
to 2056(ie 68,000 x 3.4)
12. The OECD/NEA estimate should be treated as a minimum as it excludes non-OECD
countries, including Bulgaria, Rumania and Yugoslavia that are known to have received
large depositions of Chernobyl fallout. It is not possible to make an estimate of thecollective doses in these countries, as information on the populations affected by the
Chernobyl depositions is not available. However, their collective doses may have been
relatively large.
C. Collective Doses in the Rest of the World (excluding the whole of Europe)
13. Bennett (1995) estimates a collective dose commitment of 66,000 person Sv andAnspaugh et al (1988) 28,000 person Sv to all areas of the world outside Europe. In orderto check these estimates, we make an order-of-magnitude estimate from the following
assumptions• population of the Northern Hemisphere(less population in Belarus, Ukraine and Russia and rest of Europe)• Average Cs-137 deposition density throughout northern hemisphere(from 4x 1016 Bq Cs-137/surface area of 2.45 x 1014 m2)(Bennett (1996) cites range of 1,000 kBq/m2 to 0.01 kBq/m2)• Average external dose from Cs-137 density of 1 kBq/m2 1986-2056(from table 3A (ii), Annex 3A)63= 4 x 109
= 0.16 kBq/m2= 90 µSv

• Therefore average external dose from Cs-137 density of 0.16 kBq/m2 =14µSv• Add contribution from other nuclides (30% of Cs-137 dose)= 4 µSv• Add contribution from internal doses(50% of external dose - see Annex 3A, table 3A(iii))= 7 µSv___________________________________________________________________
Total average dose 1986-2056 per person= 25 µSv
Therefore the estimated collective dose = 4 x 109 x 25 Sv-6 person Sv which is ~100,000
Person Sv and which is not far from Bennett’s estimate of 66,000 person Sv.
D. Global Collective Doses
14. Table 5.4 sums the contributions from sections A to C above.
Table 5.4 Total Collective Doses from Chernobyl Discharges- person Sv
UNSCEAR OECD/NEA Cardis et
Malko IAEA/WHOArea
US DoE
Bennett(1996)al (1996)(1998)(2005b)Anspaugh(1995,et al
1996)(1988)*
Belarus,326,000
216,000
100,000 – 165,000
55,000
Ukraine210,000**
and Russia
Rest of580,000
318,000
230,000***
EuropeRest of28,00066,000World930,000
600,000
TOTAL* person Gy** see table 5.1*** see paragraph 11 of this chapter
15. The earlier study by Anspaugh et al estimated a collective dose of 930,000 person Gy(approximately the same as 930,000 person Sv) on the basis of environmental data
available at the time and the use of early dose assessment and risk models. Bennett’s
estimate of 600,000 person Sv is probably more reliable, as UNSCEAR had access tomore data and more recent data.
16. The collective dose estimates described above are not mentioned in the UNSCEAR(2000) or the IAEA/WHO (2005b) reports. We consider that some explanation for thisomission should be given, particularly as Bennett himself was the Scientific Secretary of
UNSCEAR until the late 1990s, and was Chairman of the September 2005 IAEA/WHO
Conference. His estimates were regularly cited in official reports in the 1980s and 1990s
until about 1996. From this examination of collective dose estimates, it is clear that
Bennett’s estimates are reliable and his studies still relevant.

Collective Doses From Long-Lived Nuclides
17. The worldwide distribution of some nuclides with long half-lives result in small
exposures to the population of the world (~6 billion people) for many years into the future.
This matter is not considered by any of the above studies therefore an estimate is madebelow in table 5.5. Releases of Cl-36 and Tc-99, two other globally distributed nuclides
with very long half-lives, are unknown but should be added. Global dose coefficients(person Sv/TBq) rounded to two significant figures were obtained from Simmonds et al64

(1996) and Mayall et al (1993). Estimated nuclide releases are from Kirchner and Noack(1988) and UNSCEAR (2000).
Table 5.5 Collective doses from long-lived nuclides
Nuclide Half-life
Estimated
Global Dose Coefficient(years)Release (TBq) (Person Sv per TBq
released to air)
C-14
5,740
100
110
I-129
15,700,000
0.08
9,500
Kr-85
10.7
33,000
0.004
H-3
12.3
1,400
0.002
Total

Collective
dose Person
Sv
11,000760
130
2.8
12,00018. The result of 12,000 person Sv is relatively small in comparison with the above
collective dose estimates of 600,000 and 930,000 person Sv respectively by Bennett andAnspaugh et al. But it should be kept in mind when considering predictions of excess
cancer deaths.

Comparison with other Releases
19. Bennett (1995) compared the collective dose from Chernobyl’s fallout with thecollective doses from other man-made releases. These are set out in table 5.6. It can beseen from this table that the Chernobyl accident certainly is the most serious nuclear
accident. Indeed the fallout from Chernobyl is second only to the fallout from the hundredsof atomic test bombs detonated above ground in the 1950s and 1960s.
Table 5.6 Committed Collective Doses from Man-Made Radionuclide Releases
ReleaseCollective Effective dose
person Sv
Atomic test bombs (in atmosphere) 1950s and
30,000,000
1960s
Chernobyl accident USSR 1986
600,000
Nuclear power production (to 1995)
400,000
Radioisotope production and use (to 1995)
80,000
Nuclear weapons fabrication (to 1995)
60,000Kyshtym accident USSR 1957
2,500
Windscale accident UK 1957
2,000
source: Bennett (1996)

65

Annex 5A. Bennett’s Study(i)
Bennett (1995, 1996) and UNSCEAR (1988, 1994) arrived at their estimates byusing a Cs-137 deposition vs distance relationship to make dose estimates for thenorthern hemisphere of the world. Based on Cs-137 deposition estimates in all areas of
the northern hemisphere (derived from his deposition-distance relationship and transfer
factors relevant for the latitudinal area), he derived effective dose commitments for all
regions. These doses multiplied by the populations of the regions give the collective
effective dose commitments.
(ii)
Bennett stated that a general decrease of radionuclide deposition with distancefrom the release site could be expected, with variability due to wind and rainfall
differences. In the Chernobyl accident, the release continued for ten days and the windchanged to all directions. Therefore some variability was averaged out and Bennett
observed a relatively uniform decrease in Cs-137 deposition with distance to the capitalcities or the approximate population centres of the relevant countries. A log-log plot of
average Cs-137deposition in countries outside the USSR was made of Cs-137
measurements with distances from the accident site. This allowed Bennett to determine anapproximate deposition-distance relationship ranging from about 10 kBq/m2 at 1,000 km to~ 0.01 kBq/m2 at 10,000 km. With this relationship, Cs-137 deposition densities were
estimated in all regions of the northern hemisphere where measurements were
unavailable.
(iii)
Bennett estimated that the total collective dose from the Chernobyl accident was
600,000 person Sv, distributed 53% to European countries, 36% to the former USSR, andthe remaining 11 % to the rest of the northern hemisphere. The calculations indicated that
70% of the collective dose was due to Cs-137, 20% to Cs-134, 6% to I-131 and theremaining 4% to short-lived radionuclides deposited immediately after the accident. The
lifetime dose on average was approximately 60% from external irradiation and 40% fromingestion. According to Bennett, approximately one third of the 600,000 man Sv total
effective dose committed by the accident was received during the first year following theaccident. The remainder would be delivered over “some tens of years”, mainly determinedby the 30 year half-life of Cs-137.

66

Annex 5B. Collective Dose Estimates in European countries(i) Table 5C(i) sets out collective dose estimates in European countries by the UK NRPB 45 ,the US DoE, and the OECD/NEA.
Table 5C(i) Collective Doses to European Countries. Person-Sv
Country
Population NRPB, 1987
DoE, 1987
millions(all time)(50 years)
Albania
Austria
Belgium
Bulgaria
Czechoslovakia
Denmark
FinlandFranceEast Germany
West Germany
GreeceHungary
Ireland
Italy
Luxembourg
Netherlands
NorwayPolandPortugal
Rumania
Spain
SwedenSwitzerland
TurkeyUK
Yugoslavia
TOTAL

7.4
10
5.2
4.9
55
61
9.8
3.5
56.6
0.37
14.5
4.2
9.3
37.7
8.3
6.5
52
56.6
400

940
1,100
5,600
30,0008,500
95027,000
42
1,200
2.3
57
1,000
78,000880
820
12,00058,0004,700
1,800
52,000
76
3,400
low
low
15,000149,000

OECD/NEA, 1996
(first year)
4,900
400
140
2,500
1,300
18,0003,600
370
28,000
45
950
700
58
1,700
1,400
830
2,100
67,000(ii) These estimates are difficult to compare as different studies exclude different countries
and apply to different time periods. The OECD study which was prepared by an NEA
committee of national experts is considered to be relatively reliable. Nevertheless, it only
presents an estimate for the first year after Chernobyl, during which only about 30% of thecollective dose occurs, Therefore it is necessary to increase the total 3.4 fold to extend thedoses until 2056. This would result in a European collective dose of about 230,000 person
Sv.

45

Formerly the UK National Radiological Protection Board, now subsumed within the UK Health Protection
Agency- Radiation Protection

67

Chapter 6. Predicted Excess Cancer Deaths
1. An estimate of the number of world-wide cancer deaths may be made from theestimates of collective doses in the previous chapter. The scientific justification and themethod for this procedure are set out in Annex 6A.

Predictions for Belarus, Ukraine and Russia
2. IAEA/WHO (2005a) reported the following numbers of predicted excess cancer deaths
in table 16.4 of its report.
Table 6.1 Predicted Excess Cancer Deaths in Belarus, Ukraine and Russia (fromlifetime exposures of 95 years)
Population
NumberAverage
Cancer type
Predicted excessdose Sv
cancer deaths
Liquidators
200,000
0.1
solid cancers
2,000(1986-87)
leukaemias
200
Evacuees from 30
135,000
0.01
solid cancers
150
km zoneleukaemias
10
Residents of SCZs
270,000
0.05
solid cancers
1,500
leukaemias
100
Residents of other
6,800,000
0.007
solid cancers
4,600
contamin areas
leukaemias
370
Totals7,405,000
8,930
source: table 16.4 in IAEA/WHO (2005a)

3. This table gives fairly detailed estimates of expected cancer deaths in Belarus, Ukraine
and Russia expressed over a lifetime. These estimates were previously reported in 1996
(IAEA/WHO) but they were apparently not mentioned in the IAEA Press briefings and notcommented upon in the media at the time. In September 2005, some of these data werementioned in the IAEA Press Release (2005c) issued at the IAEA/WHO conference on
Chernobyl. The IAEA Press Release stated that 4,000 excess cancer deaths were
expected. It is considered that this statement was being “economical” with the data in table
6.1 above. It would appear that the IAEA decided to refer only to the expected deaths
among those who received higher doses, ie the liquidators and residents of Severely
Contaminated Zones (SCZs). The other lower dose categories were ignored. At the least,
this is a manipulative use of data. At worst, it is a misleading use of data, as the real figure- as can be seen above - is nearly 9,000 excess cancer deaths.

Global Predictions of Excess Cancer Deaths
4. If we assume that the linear no-threshold hypothesis of radiation’s effects is correct, we
may apply a risk factor 46 to the collective doses cited in Chapter 5 to derive predictions of
the excess cancer deaths that will result from Chernobyl exposures. Table 6.2 sets out thepredictions by various international studies of the numbers of excess cancer deaths from
Chernobyl. Uncertainties inevitably surround these estimates, but they serve to indicate
the probable magnitude of the effects of the Chernobyl disaster. They are our best46

expressed in cancer deaths per sievert. 5% per Sv means that if 100 people were each exposed to 1 Sv ofradiation, there would be 5 excess deaths from radiation-induced cancer

68estimates given the currently available information, although few of these excess deaths
are likely to be discernible by epidemiology studies.
Table 6.2 Predicted Excess Cancer Deaths from Exposure to Chernobyl Discharges
Study
Population
Risk factor used
ExcessPer Svcancerdeaths
IAEA/WHO Press
Belarus, Ukraine
assumed to be 5%
4,000
Release (2005c)
and Russia
Cardis et al, 1996
Belarus, Ukraine
11% inferred from data
~9,000and Russia
Malko (1998)
Belarus, Ukraine
13% inferred from data
22,000and Russia
Rytomaa (1996)
World
5% inferred from data
30,000US DoEWorld~3%
28,000(Goldman, 1987)
US-NRC, 1987
World
~1.5% inferred from data
14,000UNSCEAR 1988
World
5%
30,000(Bennett, 1996)
in greyed cells, prediction is calculated by this report (ie 5% of 600,000 person Sv)
5. The figure of 4,000 reported in the IAEA/WHO Press Release (2005c) at the
IAEA/WHO Conference on Chernobyl held in Vienna in September 2005 is the lowest
value of predicted excess fatal cancers in table 6.2. In terms of good scientific practice, itwould have been preferable for the IAEA/WHO report to place its estimate in the context ofother published predictions of excess cancer deaths.
Radiation Risk Estimates and DDREFs
6. Table 6.2 indicates that various authors use different radiation risk estimates to predict
the numbers of excess fatal cancers. The current ICRP recommendation (ICRP, 1991) is
to apply an average risk factor (over all populations, ages and sexes) of 5% per Sv for fatal
cancers. This risk figure comes from studies of the Japanese atomic bomb survivors.
However, the risk factor from Japan 47 is halved because the ICRP takes the view thatradiation at low doses and low dose rates (like that from Chernobyl fallout) is lessdangerous than high dose, high dose rate radiation (like that from the atomic bomb blast).
In scientific jargon, this is known as applying a dose and dose-rate effectiveness factor(DDREF) of 2.
7. The ICRP’s rationale has been that animal and cell studies show low doses of radiation
at low dose rates to be less damaging than high doses at high rates. However, the BEIR
VII Committee of the US National Academy of Sciences on ionising radiation has taken adifferent view of the evidence. Its recent report (BEIR, 2005) recommends that a median 48
DDREF of 1.5 rather than 2 should be used for solid cancers. This in turn suggests thatthe correct risk factor for most cancers should be increased from 5% to about 7% per Sv.

47

the most recent estimate from the atomic bomb survivors (Preston et al, 2003) is an average of 12% per
Sv48
with a range of 1.1 to 2.3

69

8. As regards DDREFs, it is notable that the US EPA (1994) has not used a DDREF forbreast and thyroid cancers for many years. Also, an increasing number of scientists (forexample Cardis et al, 1996; Malko,1998) refrain from using a DDREF factor, partly 49
because the supporting evidence for their use are animal and cell studies and not humanepidemiology studies. Indeed, two recent epidemiology studies (Cardis et al, 2005b;
Krestinina et al, 2005) indicate the opposite, ie that exposures to protracted radiation might
be more not less damaging (as regards cancer induction) than high dose-rate exposuresby as much as 2.5 times. This matter is the subject of continuing discussion in radiation
protection circles.
9. In view of these matters, we consider that the inappropriate use of DDREFs may welllead to inaccurate estimates of future cancer deaths. For this reason, we set out in table
6.3 a range of estimated excess cancer deaths using reasonable risk factors derived fromdifferent values for DDREF and from not using a DDREF.
Table 6.3 Predicted Excess Cancer Deaths from Exposure to Chernobyl Discharges
Study
Population
Risk factor used
ExcesscancerdeathsUNSCEAR 1988
World
10% per Sv
60,000(Bennett, 1996)(using no DDREF)
UNSCEAR 1988
World
6.7% per Sv
40,000(Bennett, 1996)(using BEIR DDREF of 1.5)
UNSCEAR 1988
World
5% per Sv
30,000(Bennett, 1996)(using ICRP DDREF of 2)
greyed cells = calculated by this report from data in Bennett, 1996
10. In table 6.3, we derive three predictions of excess cancer deaths, and our best
estimate lies in the range 30,000 to 60,000. Although our predictions are higher than otherestimates of predicted excess cancer deaths by Goldman (1987) and Rytomaa (1996) –see table 6.2, they have been derived using a simple scientific procedure. If future studies
were to confirm that a DDREF should not be applied (ie that the Japanese risk estimatesshould not be divided by any figure), then the higher figure of our estimated range would
be applicable. If future epidemiology studies were to go further and indicate that protracted
radiation might be more rather than less damaging (as regards cancer induction) than highdose-rate exposures, then the above estimates would need to be increased still further.
Inappropriate Comparisons with Background Radiation
11. Official reports (eg IAEA/WHO, 2005a) often compare the numbers of expected excess
cancer deaths with the much larger numbers of cancer deaths expected from backgroundradiation over the same time period. In our view, such comparisons are inappropriate, as
they conflate man-made radiation with naturally-occurring radiation. They may also be
misleading because they invite the uninformed public to infer that background radiation issomehow “safe”. In reality, background radiation is a killer. For example, the former UK
NRPB has calculated that an average background dose rate of 2.6 mSv/a in the UK
population results on average in about 6,000 to 7,000 future cancer deaths per year (Robb1994). This matter is explored further in Annex 6B.

49

also because the use of DDREFs is inconsistent with the accepted practice of extrapolating risks linearly
from data at high doses to low doses

70Annex 6A. Collective Dose and the Linear No-Threshold Theory(i) Epidemiology evidence exists of an excess risk of radiation-induced cancer at doses atleast as low as 10-50 mSv and that this risk is directly proportional to dose. The latest
study of cancer in nuclear industry workers (Cardis, 2005c), in which the overall average
cumulative recorded dose was 19.4 mSv, suggest, according to the authors that ‘anexcess risk of cancer exists, albeit small, even at the low doses and dose rates typicallyreceived by nuclear workers in this study’. The most recent follow-up of the Hiroshima andNagasaki survivors (Preston et al, 2003) shows that ‘the excess solid cancer risks appear
to be linear in dose even for doses in the 0-150 mSv range’. In the particular case of
thyroid cancer, there is evidence that the risk is directly proportional to dose, down todoses as low as 10 mSv (Ron et al, 1995).
(ii) However, at doses of a few mSv or lower, risks have to be inferred by extrapolationfrom higher doses, as epidemiology studies would require unfeasibly large numbers ofpeople to be studied to achieve adequate statistical power. Radiobiology can help here:
because the transformation of a cell to a pre-cancerous state may result from the lowest
possible dose of radiation - a single radiation track traversing a single cell nucleus – goodreasons exist for supposing that the risk is directly proportional to dose right down to zero,i.e. there is no-threshold (NRPB, 1995; Stather, 1995).
(iii) The ICRP’s view (2004) is that the LNT relationship should be used as it provided a“conservative” estimate of risks. The word “conservative” has a special meaning inradiation protection. It means that because, in the ICRP’s view, the real risk is likely to belower, acting on the higher risk estimate gives an added safety margin. Recently, aneminent group of the world’s foremost radiobiologists re-affirmed the LNT and stated that itprovided a real estimate of radiation risks and not a “conservative” one (Brenner et al,2003).
(iv) Assuming the risk of cancer is directly proportional to dose with no threshold, it follows
that the number of cancer deaths can be estimated as follows:• number of cancer deaths = number of people exposed x average dose (Sv) x risk
factor (cancer deaths per Sv)• the product (numbers exposed x average dose) is the collective dose, so• predicted number of excess cancer deaths = collective dose x risk factor(v) More detailed discussions of collective dose are contained in Fairlie and Sumner(2000) and Sumner and Gilmour (1995), and of the biological justification for the LNT in
Brenner et al (2003).

71Annex 6B. Inappropriate Comparisons with Background Radiation(i) Offical reports often compare collective doses from man-made radiation with the muchlarger collective doses received from background radiation, in attempts to put them "incontext". Such comparisons invite the public to conclude that, because doses from manmade radiation are smaller than those from background radiation, they are therefore
acceptable. Many objections can be made against these assertions.
(ii) First, comparisons with natural background doses invite the inference that backgroundradiation is “safe”. This is not the case, of course: background radiation is a killer. For
example, the former UK NRPB has calculated, using a 5% per Sv risk factor, that an
average UK background dose rate of 2.6 mSv per year in a population of 55 million will
result on average in about 6,000 to 7,000 future cancer deaths per year, about 4% to 5%of the 160,000 cancer deaths occurring each year in the UK (Robb, 1994).
(iii) Second, comparisons with background radiation conflate different risks, ie naturallyoccurring and anthropogenic risks. Risks from anthropogenic releases are (or were in thecase of past exposures) subject to by social and political decisions. Risks frombackground radiation are not.
(iv) Third, it is notable that comparisons with background are not used to justify theacceptability of industrial discharges of chemical toxins that also occur naturally, such asaflatoxin, ozone or dioxin.
(v) Finally, and notably, the current ICRP system of radiation protection of limitation,
optimisation and justification (ICRP, 1991) notably does not use comparisons with natural
background radiation as a criterion of radiological acceptance. This is a deliberateomission, as the issue of using background radiation has often been discussed at ICRP
committee meetings. In recent years, the past chairman of the ICRP had attempted tojettison the ICRP’s principles and to introduce background radiation as a criterion of
acceptance. These attempts failed as they were not supported during the ICRP’s
consultations on updating its 1991 recommendations which took place in 2004. Indeed, inthe past, many scientists have stated (NRPB, 1990), (Webb et al, 1983), (section 8.3.4 in
Bush et al, 1984) that comparisons of radiation exposures from anthropogenic releases
with natural background radiation are inappropriate.

72

Chapter 7. Conclusions
1.
It is widely agreed that the Chernobyl disaster was unprecedented and unique inthe history of civil nuclear power. Its effects are clearly still occurring and the fullconsequences may take centuries to unfold. Even then, it is likely that many details will
never be known.
2.

The main conclusions of our report are• about 30,000 to 60,000 excess cancer deaths are predicted, 7 to 15 times greaterthan IAEA/WHO’s published estimate of 4,000• predictions of excess cancer deaths strongly depend on the risk factor used
• predicted excess cases of thyroid cancer range between18,000 and 66,000 in Belarus
alone depending on the risk projection model used
• other solid cancers with long latency periods are beginning to appear 20 years after
the accident• Belarus, Ukraine and Russia were heavily contaminated, but more than half ofChernobyl’s fallout was deposited outside these countries• fallout from Chernobyl contaminated about 40% of Europe’s surface area
• collective dose is estimated to be about 600,000 person Sv, more than 10 times
greater than official estimates• about 2/3rds of Chernobyl’s collective dose was distributed to populations outside
Belarus, Ukraine and Russia, especially to western Europe• Cs-137 released from Chernobyl is estimated to be about a third higher than official
estimates
Recent IAEA/WHO studies3.
Our verdict on the two recent IAEA/WHO (2005a, 2005b) studies on health andenvironment respectively is mixed. On the one hand, we recognise that the reports
comprehensively examine Chernobyl’s effects in Belarus, Ukraine and Russia. They
contain a great deal of important information which will repay future study. Clearly muchscientific effort was put into the reports by the respective scientific teams and theirchairpersons, and they are welcomed for this reason.
4.
On the other hand, the reports contain some deficiencies, for example the lack of
discussion on Chernobyl’s source term and the low estimates of collective dose in Belarus,
Ukraine and Russia. Significantly they are silent 50 on Chernobyl’s effects outside Belarus,
Ukraine and Russia. Most of Chernobyl’s fallout was deposited outside these countries.
Countries in the rest of the world, especially in Europe, will suffer twice as many predictedexcess cancer deaths (and collective doses) as Belarus, Ukraine and Russia.
5.
We recognise that the failure to examine Chernobyl’s effects in all other countries
does not lie with the scientific teams but with higher echelons of the IAEA and the WHO.
We recommend that the WHO, independently of the IAEA, should now commission areport to examine Chernobyl’s effects in all other countries in order to rectify the omission.
50

except for one table on Cs-137 contaminatio n levels in a few Europeam countries73

We also recommend that UNSCEAR, presently located within the IAEA’s headquarters in
Vienna, should be relocated to a more neutral venue.
Uncertainties
6.
As we have shown in this report, the reconstruction of the accident and theprediction of its health consequences involve many uncertainties: in the size of the source
term, the distribution of fallout, the relationship of contamination to doses received, and theestimation of health effects from radiation doses. To estimate the likely effects, value
judgements have to be made; values of various parameters have to be assumed when weuse models; and some assumptions may be arbitrary. This is particularly the case withpredictions of excess cancer deaths from Chernobyl’s collective doses. These strongly
depend on the risk factor used, but divergent views exist on what is the correct factor. Up
to a few years ago, 5% per Sv was widely used: nowadays 10% per Sv or more isincreasingly used. This obviously results in increased numbers of predicted excess cancer
deaths, therefore close scrutiny of the risk factor used is needed.
7.
As a result, many of the doses, predicted effects and risks we cite in this report will
be subject to considerable uncertainties. We draw attention to these uncertainties andrecommend that a precautionary approach be adopted when using them.
Scientific Lessons
8.
Many lessons are still being learned from Chernobyl. Some of them should alreadybe part of the scientific approach, but at the risk of stating the obvious, we set them out
below
(i)

(ii)

(iii)

We must not jump to conclusions, especially about the absence of radiation
effects with long latency periods. The studies published so far have follow-up
periods that are smaller than the typical latency periods for solid cancers
induced by radiation. Many studies are still in progress, and their results areawaited. For example, the follow-up studies of the atomic bomb survivors, whichhave now continued for more than 60 years, are still yielding new, andsometimes surprising, information.
Many years ago, a British politician, Oliver Cromwell, stated: “Always think it
possible that thou art mistaken”. It has now been shown that the initial
scepticism that greeted the first reports of childhood thyroid cancer from
Chernobyl was unjustified. This should make us more careful about deciding
what is and what is not a radiation effect. In other words, we need to keep a very
open mind on Chernobyl’s effects.
“Absence of evidence is not evidence of absence” (Altman and Bland, 1995). A
real effect can elude detection because of low statistical power, often because
the samples are too small. The lack of statistical power is a recurrent theme inmany of the studies published so far.

The Future9.
As for the future, we recommend that follow-up studies are continued andbroadened, with satisfactory funding and the involvement of independent scientists. A
good model in this respect is the Radiation Effects Research Foundation (RERF) in Japan,
74

which continues to follow-up effects in the atomic bomb survivors and whose funding is
independently secured. In this connection, we note the apparent lack of independence inthe relations between the WHO and the IAEA as regards the WHO’s studies on Chernobyl
effects. The WHO should be able to carry out health-related research and publish healthreports on radiation matters independently of the IAEA, just as other UN agencies publish
reports independently of each other. In our view, there is no reason why the WHO alone
should not investigate these matters and publish its results without the permission of the
IAEA.
10.
Collaborative work is sometimes limited by the inability of Western scientists to gain
access to, and/or translate, many scientific reports written in Ukrainian and Russian.
These language constraints inhibit a full understanding of the impacts of Chernobyl; wedraw attention to this difficulty and to the need for it to be tackled at an official level. In thepast, laudable attempts have been made with this aim (Shershakov and Kelly, 1996) but
translations of more recent reports are needed.
11.
Finally, there remains the question of the future of nuclear power. A number ofcountries are currently considering the renewal and/or enlargement of their nuclear power
programmes. Chernobyl should give us all pause for thought before we embark on any
revival of nuclear power. Even though future reactors have been stated to be inherently
safer than the Chernobyl design, accidents can still occur and it is important that robust
plans are agreed internationally for dealing with any future accidents (see Williams, 2001).
We should keep in mind the view of the philosopher George Santayana that those who areunable to learn from history are condemned to repeat it.

75

Afterword
THE CURRENT SITUATION IN UKRAINE: February 2006
Professor A. NYAGU
President of "Physicians of Chernobyl" Association
8, Chernovol str.
Kiev 01135
Ukraine
The radiation accident at Chernobyl in April 1986 is still affecting the lives of many people
in Ukraine and is still determining its national economic policy. There are many problems
in Ukraine resulting from radio-ecological Chernobyl catastrophe including:• the remaining reactors at Chernobyl which are currently closed;• the “Shelter” and its reconstruction;• the exclusion zone and radioactive waste - there are more than 800 temporarystorage places for radioactive wastes containing about 300,000 Ci (Cs), 12,000 Ci(Sr) and 300 Ci (Pu) and about 110,000 Ci (Cs), 44,000 Ci (Sr) and 110 Ci (Pu) inpermanent stores (7);• the radioecological monitoring of 4.8% of the surface area of Ukraine (including
2,300 settlements);• the radiological monitoring the Dneiper river water basin, which provides water for
32 million people and for the irrigation of 1.8 million hectares of land;• the health monitoring of over 2,646,000 citizens, including 643,000 children, whoreceived acute radiation doses during the accident and are still exposed to low
doses of radiation in the contaminated territories;• the social protection of these citizens and personnel of the Chernobyl nuclear
plant, including residents of Slavutich town.
As a result of the accident, 2,300 settlements in 12 Ukraine Oblasts were exposed toradioactive contamination. This corresponds to 55,000 km2 including some 25,000 km2 offorests. In addition, in 1986, 91,000 people were evacuated from the 30 km exclusion zone
around Chernobyl. Where Cs-137 contamination levels exceeded 555 kBq/m2, (ie II zone),compulsory evacuation was required in Ukraine. These contamination levels were
estimated to result in an annual exposure of >5 mSv, five times greater than the legal limit.
The radiation dose criteria for the zone of guaranteed settlement (III zone) is 1 to 5 mSv
and for the zone of strengthened ecological control (IV zone) is 0.1 to 0.5 mSv. The lesser
contaminated zones III and IV are presently used for agricultural production. The
Chernobyl accident stopped traditional methods of forestry engineering. There is now aneed to introduce new technologies and new work equipment to be used in conditions ofradioactive contamination (2, 3, 7).
Ukrainian experts estimate the economic damage to Ukraine will be $200 billion up to2015 (7, 9). In comparison, Ukraine’s GDP in 2001 was $37 billion. In 1992, Ukraine spent
15% of its entire budget dealing with the effects of Chernobyl. In 1996, the figure was 6%,
and in recent years it has been 5% (4, 9).
The radiation exposures to the Chernobyl liquidators ranged between 50 mSv and 7 Sv.(1)Evacuated people from the 30 km exclusion zone received exposures between 10mSv
and >700 mSv. People in contaminated areas in Ukraine, by conservative calculations,76

received exposures between 2 to 74 mSv (1, 4). Their total accumulated collective doseamounts to 46,000 man/Sv. The International Chernobyl project (1991) expected that the
average exposure to those in contaminated areas during 70 years (1986-2056) will amountto 160 mSv. This means that the Ukraine population in contaminated areas will continue tobe exposed to radiation for many years. About 80-95% of radiation doses are from theconsumption of contaminated food (milk, meat, vegetables, forest products), and theremainder is from external radiation – primarily surface Cs-137.
In accordance with the Law of Ukraine on “Status and Social Protection of Citizens
Affected by Chernobyl Catastrophe,” about 7% of Ukraine's population was affected by
Chernobyl, not including the citizens of Kiev (although they were also irradiated). By 2005,
this amounted to 2, 646, 000 citizens, including (9):••••165,000 residents of evacuated areas
253,000 liquidators
643,000 children born to the accident liquidators, and1,563,000 people from 2, 293 settlements in contaminated areas

9, 500 people in 1,337 families still remain in zones of compulsory evacuation. For thesepeople, life is very difficult and amounts to a humanitarian catastrophe. They lack all
infrastructure, all services, the right for land use, and all medical care. They are subject tovery high exposures from radioactive contamination. Most young families abandoned
these lands independently without assistance and a dramatic ageing of the population took
place.
In 2004, more than 2,320,000 Chernobyl survivors continued to receive periodic medical
examinations. The Ukraine National Registry system has registered all Chernobyl
survivors and has commenced automatic long-term health monitoring. By January 2005,
the Registry had compiled information on 2,240,000 persons. The percentage of the adult
population diagnosed ill after medical examination, is constantly growing. At present, 94%
of accident liquidators, 89% of evacuees; 85% of residents of radioactively contaminatedterritories, and 79% of children directly or indirectly affected by the accident are officiallyconsidered ill under the Ukraine National Registry. These indices, although very large,
could in fact be worse if screening were carried out thoroughly. But there is neither thefinance nor political will for thorough screening in Ukraine.
According to the dose distribution in the Ukrainian population in 1986, thyroid exposures inchildren were distributed as follows (7, 12):• ~85% of all children < 3 years old and children irradiated in utero received
between 0.1 and 1 Gy;• about 60% of children 4-15 year old and 50% of teenagers received between 50300 mGy;
• >15, 000 children born between 1979-1986 before the accident received morethan 2 Gy.
By January 2005, 3,270 patients had been operated on for thyroid cancer in Ukraine (9).
Children from 17,000 communities (ie 60% of all communities of Ukraine) received thyroid
doses greater than the limits in force. The total collective dose to the thyroid in Ukraine isestimated to be 1,300,000 man/Gy, of which about half (607,000 man/Gy) is to 0-18 year
olds. Also the cumulative incidence of thyroid diseases is expected to increase in future.
(7, 12) Various experts estimate that the lifetime risk of thyroid cancer for children who
77

were 0-4 years old at the time of the accident will reach 30%. (12, 13). These estimatescannot be treated as final (12) until the completion of cohort epidemiology studies (overthe next 20 years when all the radiation–induced thyroid cancers in the exposed
population will have arisen).
For cancers in the exposed adult population, there has been a 2-fold increase in breast
cancer, and a 2 to 7 fold increase in thyroid cancer. (7)In the post-accident period, increases in cardiovascular, neurological, respiratory,
digestive, and bone-muscular diseases have been registered among the affected
populations. Over 105,000 disabled exposed people are registered in Ukraine, including
over 2,000 children. They are disabled from diseases related to a complex of factors fromthe Chernobyl catastrophe and require annual therapy. The children are registered as
invalids due to cancers, congenital malformations, and diseases of endocrine, nervous,
respiratory and digestive systems. (8)Genomic instability from long-term low-level radiation exposure is a newly discovered
effect which remains under investigation. Uptakes of low levels of caesium, strontium,
plutonium and other radionuclides by mothers and their fetuses may cause additional
cancers, leukaemias and congenital diseases in the first generation. This makes the
problem especially urgent. Unfortunately, there is little coordination between postChernobyl researchers in Ukraine, as there has been no systematic collection,
standardisation and evaluation of findings as yet. This means that valuable findings are notproperly analyzed or compared with other findings. Data from the National Chernobyl
Registry are not properly assessed which makes it impossible to estimate the real levels ofradiation effects on the population from the accident at present. The main health effects
considered to be connected to Chernobyl exposures are cancers and diseases of the
cardiovascular, blood and nervous systems; and among children – cancers and congenital
malformations.(9).
During 2005, mortality indices increased slightly among the population affected by
Chernobyl and total mortality in Ukraine also increased. Mortality indices among liquidators
are constantly increasing. The highest mortality level is among the adult population
resident in radioactively-contaminated territories. At the same time, birth rates in all
observation groups are distinctly decreasing. Taking into account a decreased latency
period of oncological abnormalities, the survival of Chernobyl victims becomes even more
problematic. (9)It is widely accepted that the Chernobyl accident has resulted in a complex of direct andindirect factors which adversely affect the health of exposed people. These factors are
considered by the affected people themselves to be significant and dangerous. They
include the following:• radioactive contamination of the environment by caesium, strontium, andplutonium• ingestion of contaminated food• anxiety over higher illness rates among children.
On the 4th International Conference on «Chernobyl Children – Medical Consequences andSocio-Psychological Rehabilitation», a persistent complex of post-accident pathogenic
factors was reported (11). This complex included radiation exposure, psychological stress,78

evacuation and resettlement with subsequent socio-economic effects etc., all of which
adversely affected the somatic and psychological health of children.
Long-term monitoring in the three affected countries has made it possible to select cohortsof children and teenagers exposed to radiation, with a view to• continued observation of genetic and oncological diseases;• epidemiology investigations on the health of survivors of different ages;• studies on new approaches to the diagnosis, prophylaxis and treatment of low
dose radiation-related diseases (with special attention to molecular-genetic
studies and estimating the impact of genomic instability on morbidity of offspring);• changing approaches to overcoming of psychosocial problems of affectedchildren.
The Conference also demonstrated that epidemiology research had been conducted on
thyroid cancer in children and teenagers at the time of the accident, when studies onradiation-induced non-cancer diseases were lacking. (11)Abnormal psychological development has been detected in 60-70% of children andteenagers exposed to radiation. This is two times higher than among general population.
More than 60% of teenagers see their futures away from home because radiation
pollution; (7, 10) affected areas would suffer from depopulation and decline if thisoccurred. Therefore, the coordination of efforts between governments, internationalorganizations and voluntary organizations and all people of goodwill towards the solutionof this complex of economic, ecological, medical and social problems of affected children
and youth is very important. (8, 10).
The report of the UNDP Chernobyl Program in Ukraine in 2003-2005 revealed that thechronic crisis in the Chernobyl community resulted from its extremely low material status
which restricted its access to medical care.(6) All affected people point to the extremely
low level of medical care at the place of dwelling and the very high costs of better healthcare at oblast centres and in Kiev. The international community has been informed about
the humanitarian needs of the affected people, and since 1986 has rendered the affected
people invaluable assistance (6, 7, 10).
The UN report Human Consequences of the Chernobyl Nuclear Accident: A Strategy for
Recovery outlined a ten-year strategy for tackling and reversing the downward spiral ondevelopment. (5) It is clear that the environmental effects of Chernobyl cannot be
considered in isolation from its social, economic and institutional aspects within Ukraine.
The international and national communities are interested not only in the safety of thereactor Sarcophagus but also in the knowledge to be gained about the long-term effects ofradioactive fallout on health, and disaster management and rehabilitation needed in postaccident responses. However, scientific interest in the lessons of Chernobyl cannot besatisfied in isolation from the well-being of those whose lives have been shattered by
Chernobyl (10, 11).
There is little doubt that the Ukraine will have to undergo a long-term period of
rehabilitation. In order to realize the program on the minimization of Chernobyl’s socialeconomic, health, and radio-ecological effects, it will be necessary to mobilize not only
national efforts but also the efforts of international communities. Chernobyl in Ukraine is
not only a painful memory of the past, but a major current problem and an even greater
future challenge (5).
79

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Acronyms and Abbreviations(see Annex 4 for radiation dose units and SI nomenclature)
AFMT
ARAC
BfS
Bq
CERRIECi
CRIIRADDDREF
DG TREN
DNA
DoE
EC
ECLIS
EPA
ERR
EU
Gy
IAEA
IARC
ICP
ICRP
IPHECA
LET
LNT
NEA
NCI
NRC
NRPB
OCHA
OECD
RERF
SCPRI
Sv
UNDP
UNICEFUNSCEAR
USSR
WHO

L'Association Française des Malades de la Thyroïde
Atmosphere Release Advisory Centre, Lawrence Livermore ResearchLaboratory, US
German Federal Office for Radiation Protection
becquerel (unit of radioactivity)
UK Committee Examining the Radiation Risks of Internal Emitterscurie (unit of radioactivity)
Commission de Recherche et d'Information Indépendantes sur laRadioactivité
dose and dose rate effectiveness factor
Directorate-General for Transport and Energy of the EC
deoxyribose nucleic acid
US Department of Energy
European Commission
IARC European Childhood Leukaemia-Lymphoma Incidence Study
US Environmental Protection Agency
excess relative risk
European Union
gray (unit of absorbed radiation dose)International Atomic Energy Agency
International Agency for Research on Cancer
International Chernobyl ProjectInternational Commission on Radiation Protection
International Project on the Health Effects of the Chernobyl Accident
linear energy transfer
linear no-threshold (theory of radiation’s dose-effect relationship)
Nuclear Energy Agency of the OECDUS National Cancer Institute
US Nuclear Regulatory Commission
former UK National Radiological Protection Board
UN Office for the Coordination of Humanitarian Affairs
Organisation for Economic Cooperation and Development
Radiation Effects Research Foundation
French Government Central Service for Protection against Radiation
sievert (unit of equivalent or effective radiation dose)
United Nations Development Programme
United Nations Children’s Fund
United Nations Scientific Committee on the Effects of Atomic Radiation
former Union of Soviet Socialist Republics
World Health Organisation91