Report of the United Nations Scientific Committee on the
Effects of Atomic Radiation to the General AssemblyContents
ChapterPage

I.

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

II.

Deliberations of the United Nations Scientific Committee on the Effects of Atomic Radiation
at its sixtieth session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2A.

Completed evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2

B.

Present programme of work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

1.

III.

Radiation exposures from electricity generation and an updated methodology for
estimating human exposures due to radioactive discharges . . . . . . . . . . . . . . . . . . . .

3

2.

Biological effects from selected internal emitters . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

3.

Epidemiology of low-dose-rate exposures of the public to natural and artificial
environmental sources of radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4.

Development of an evaluation of medical exposures . . . . . . . . . . . . . . . . . . . . . . . . .

3

5.

Outreach activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4C.

Strategic plan for 2014-2019 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

D.

Future programme of work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5E.

Administrative issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5

Scientific findings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

A.

Levels and effects of radiation exposure due to the nuclear accident after the 2011 greateast-Japan earthquake and tsunami . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6

1.

The accident and the release of radioactive material into the environment . . . . . . .

6

2.

Dose assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

3.

Health implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10

4.

Radiation exposures and effects on non-human biota . . . . . . . . . . . . . . . . . . . . . . . . .

11

Effects of radiation exposure on children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12Members of national delegations attending the fifty-eighth to sixtieth sessions of the United
Nations Scientific Committee on the Effects of Atomic Radiation . . . . . . . . . . . . . . . . . . . . . .

15

Scientific staff and consultants cooperating with the United Nations Scientific Committee on
the Effects of Atomic Radiation in the preparation of its scientific report for 2013 . . . . . . . . .

17

B.
Appendices
I.
II.

v

REPORT TO THE GENERAL ASSEMBLY

Chapter I
Introduction
1.
Since the establishment of the United Nations Scientific Committee on
the Effects of Atomic Radiation by the General Assembly in its resolution
913 (X) of 3 December 1955, the mandate of the Committee has been toundertake broad assessments of the sources of ionizing radiation and its
effects on human health and the environment.1 In pursuit of its mandate, theCommittee thoroughly reviews and evaluates global and regional exposuresto radiation. The Committee also evaluates evidence of radiation-induced
health effects in exposed groups and advances in the understanding of thebiological mechanisms by which radiation-induced effects on human healthor on non-human biota can occur. Those assessments provide the scientificfoundation used, inter alia, by the relevant agencies of the United Nations
system in formulating international standards for the protection of thegeneral public and workers against ionizing radiation;2 those standards, inturn, are linked to important legal and regulatory instruments.
2.
Exposure to ionizing radiation arises from naturally occurring sources(such as from outer space and radon gas emanating from rocks in the Earth)and from sources with an artificial origin (such as medical diagnostic andtherapeutic procedures; radioactive material resulting from nuclear weapons
testing; energy generation, including by means of nuclear power; unplanned
events such as the nuclear power plant accidents at Chernobyl in 1986 andfollowing the great east-Japan earthquake and tsunami of March 2011; andworkplaces where exposure to artificial or naturally occurring sources ofradiation may be increased).

__________________
1 The

United Nations Scientific Committee on the Effects of Atomic Radiation wasestablished by the General Assembly at its tenth session, in 1955. Its terms of reference
are set out in resolution 913 (X). The Committee was originally composed of thefollowing Member States: Argentina, Australia, Belgium, Brazil, Canada,
Czechoslovakia (later succeeded by Slovakia), Egypt, France, India, Japan, Mexico,
Sweden, Union of Soviet Socialist Republics (later succeeded by the RussianFederation), United Kingdom of Great Britain and Northern Ireland and United Statesof America. The membership of the Committee was subsequently enlarged by the
Assembly in its resolution 3154 C (XXVIII) of 14 December 1973 to include theFederal Republic of Germany (later succeeded by Germany), Indonesia, Peru, Poland
and the Sudan. By its resolution 41/62 B of 3 December 1986, the Assembly increased
the membership of the Committee to a maximum of 21 members and invited China tobecome a member. In its resolution 66/70 of 9 December 2011, the Assembly further
enlarged the membership of the Committee to 27 and invited Belarus, Finland, Pakistan,
the Republic of Korea, Spain and Ukraine to become members.
2 For example, the international basic safety standards for protection against ionizing
radiation and for the safety of radiation sources, currently co-sponsored by theInternational Labour Organization, the Food and Agriculture Organization of the United
Nations (FAO), the World Health Organization (WHO), the International Atomic
Energy Agency (IAEA), the Nuclear Energy Agency of the Organization for Economic
Cooperation and Development and the Pan American Health Organization.

12 UNSCEAR 2013 REPORT

Chapter II
Deliberations of the United Nations Scientific Committee on the
Effects of Atomic Radiation at its sixtieth session
3.
The Scientific Committee held its sixtieth session in Vienna from 27 to
31 May 2013.3 Carl-Magnus Larsson (Australia), Emil Bédi (Slovakia) andYoshiharu Yonekura (Japan) served as Chair, Vice-Chair and Rapporteur,
respectively. The Committee took note of General Assembly resolution
67/112 on the effects of atomic radiation.

A.

Completed evaluations
4.
The Committee discussed in detail two substantive scientificdocuments. The principal findings of those two documents are summarized
in a scientific report (see chap. III below) and, together with the two detailed
scientific annexes that underpin the findings, will be published separately inthe usual manner, after comments from the Committee have been addressed.
The first document reported the results of an assessment of the levels
5.
and effects of radiation exposure due to the nuclear accident after the 2011
great east-Japan earthquake and tsunami. The General Assembly, in its
resolution 66/70, had endorsed the Committee’s decision at its fifty-eighth
session to conduct that assessment. The Committee acknowledged that it had
been a major undertaking that had required efforts well beyond the resources
normally available to the Committee and its secretariat. Over 80 experts
from 18 countries and 5 international organizations had been involved in thework, constituting a major contribution in kind, and prepared material for theCommittee’s scrutiny at its sixtieth session. The experts had collected andreviewed data and information, and defined methodologies and processes for
ensuring the quality of the data and for their use. Germany, Sweden and
Switzerland had made financial contributions to the general trust fund tosupport the work of the Committee in this regard. An expert (offered by theGovernment of Japan under a non-reimbursable loan arrangement) had been
assisting the secretariat in Vienna.
There were many sources of data: (a) specific datasets in electronic
6.
formats and supplementary information requested of the Government ofJapan and other authenticated Japanese sources; (b) results of measurements
and evaluations made by other United Nations Member States; (c) datasets
made available by international organizations, including the Preparatory
Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization(CTBTO), the Food and Agriculture Organization of the United Nations(FAO), the International Atomic Energy Agency (IAEA), the World HealthOrganization (WHO) and the World Meteorological Organization; (d)information and independent analyses published in peer-reviewed scientificjournals; and (e) measurements made by non-governmental organizations.

__________________
3 The sixtieth session of the Committee was also attended by observers for FAO, WHO,the International Agency for Research on Cancer, the World MeteorologicalOrganization (WMO), IAEA, the Preparatory Commission for the Comprehensive
Nuclear-Test-Ban Treaty Organization (CTBTO), the European Commission, theInternational Commission on Radiological Protection, and the International
Commission on Radiation Units and Measurements.

REPORT TO THE GENERAL ASSEMBLY

37.
The Committee also discussed a substantive scientific document that
represented an extensive review of the effects of exposure to ionizing
radiation during childhood. The Committee had decided at its fifty-seventhsession (16-20 August 2010), in deliberations on its future programme ofwork, that it should undertake to address radiation risks for and effects onchildren, to help clarify how those risks and effects were different forchildren and adults. The delegation of the United States of America had led
the preparation of detailed technical documents on this subject, which had
been discussed at the fifty-eighth (23-27 May 2011) and fifty-ninth sessions(23-27 May 2012).

B.

Present programme of work

1.

Radiation exposures from electricity generation and an updated methodology
for estimating human exposures due to radioactive discharges
8.
The Committee discussed two progress reports, one on an evaluation ofradiation exposures from electricity generation and the other on updating theCommittee’s methodology for estimating human exposures due toradioactive discharges into the environment. The Committee noted that thereview and update of the existing methodology was well advanced. It notedthat electronic spreadsheets were being developed that would implement themethodology for use in conducting the assessment of radiation exposures of
populations from various types of electricity generation. The Committee
anticipated that both documents would be ready for final scrutiny at its sixtyfirst session.

2.

Biological effects from selected internal emitters
9.
The Committee discussed progress on evaluations of the biologicaleffects of exposure to selected internal emitters, addressing two specificradionuclides: tritium and uranium. It considered that further work wasneeded, but envisaged that the two components might be ready for detailed
discussion at the Committee’s sixty-first session.

3.

Epidemiology of low-dose-rate exposures of the public to natural and artificial
environmental sources of radiation
10. The Committee discussed progress on an evaluation of epidemiologicalstudies of low-dose-rate exposures of the public to naturally occurring andartificial environmental sources of radiation. The Committee acknowledgedthat the work was progressing but envisaged that it might not be completed
before the sixty-second session.

4.

Development of an evaluation of medical exposures
11. The Committee took note of a progress report by the secretariat on
developing an evaluation of medical exposures. Because (a) exposures ofpatients undergoing medical procedures represented the most significant
source of artificial exposure to ionizing radiation, (b) technology andpractices in this area were changing rapidly and (c) this was a thematic
priority of the Committee’s strategic plan (2009-2013), the Committee hadrequested the secretariat to prepare a detailed plan for a report on thissubject. It had also requested the secretariat to initiate the Committee’s next
Global Survey of Medical Radiation Usage and Exposures and to foster close
cooperation with other relevant international organizations (such as IAEA

4 UNSCEAR 2013 REPORTand WHO), as appropriate. A web-based questionnaire on medical exposures
had been developed and was being tested. The secretariat planned to initiate
the survey during 2013 and to obtain feedback from the Committee at its
sixty-first session on preliminary findings, with a view to completing theevaluation thereafter.
12. The Committee suggested that the General Assembly might (a)encourage Member States, the relevant organizations of the United Nations
system and other pertinent organizations to provide further relevant data
about doses, effects and risks from various sources of radiation, which would
help greatly in the preparation of future reports of the Committee to the
Assembly; and (b) encourage IAEA, WHO and other relevant organizations
to further collaborate with the Committee’s secretariat to establish andcoordinate the arrangements for the periodic collection and exchange of dataon radiation exposures of the general public, workers and, in particular,
patients.
5.

Outreach activities
13. The Committee took note of progress reports by the secretariat onoutreach activities, in particular plans for the dissemination of theCommittee’s report on the levels and effects of radiation exposure due to the
nuclear accident after the 2011 great east-Japan earthquake and tsunami. It
took note of the progress that the secretariat had made in enhancing the
public website of the Committee, developing leaflets and posters andupdating a booklet to explain in plain language the findings of its recent
reports.

C.

Strategic plan for 2014-2019
14. The Committee discussed a strategic plan to provide vision anddirection for all its activities during the period 2014-2019, to facilitate
results-based programming by the secretariat, to help foster the managementof sufficient, assured and predictable resources and to improve planning andcoordination among the various parties involved.
15. The Committee considered that its strategic objective for the period
2014-2019 was to increase awareness and deepen under-standing among
decision makers, the scientific community and civil society with regard tolevels of exposure to ionizing radiation and the related health andenvironmental effects as a sound basis for informed decision-making onradiation-related issues.
16. The Committee identified its thematic priorities for the period: (a) the
global impact of energy production (including follow-up of the radiologicalconsequences of the 2011 accident at the Fukushima Daiichi nuclear power
station) and of the rapidly expanding use of ionizing radiation in medical
diagnosis and treatment; and (b) radiation effects at low doses and low dose
rates.
17. Further strategic shifts were envisaged in order to better meet the needsof Member States, including: (a) further streamlining the Committee’sscientific evaluation processes to complete both wide-ranging summary
reports on the levels and effects of radiation exposure and preparing special
reports that respond to emerging issues as the need arises; (b) further using
intersessional expert groups to develop assessment methodologies, conduct

REPORT TO THE GENERAL ASSEMBLY

evaluations and maintain surveillance on emerging issues; (c) developing
networks of experts, scientific focal points in Member States and centres of
excellence to facilitate access to expertise; (d) further enhancing mechanisms
for data collection, analysis and dissemination; and (e) further raisingawareness and improving dissemination of the Committee’s findings inreadily understandable formats for decision makers and the public.

D.

Future programme of work
18. At its previous session, the Committee had decided that the work toassess the levels of exposure and radiation risks resulting from the nuclear
accident following the great east-Japan earthquake and tsunami of March2011 and to complete an extensive review of the effects of radiation
exposure on children should take priority over other evaluations andactivities that had been initiated as part of the present programme of work.
Because those two studies were to be completed and published during thefollowing months, the Committee, in discussions about its future programmeof work, agreed to focus on completing other outstanding evaluations that
had been delayed owing to the unexpected work resulting from the accident
at the Fukushima Daiichi nuclear power station, and not to introduce further
new topics at this stage.

E.

Administrative issues
19. The Committee welcomed developments in streamlining procedures for
publishing the Committee’s reports as sales publications. Nevertheless theCommittee suggested that the General Assembly might request the United
Nations Secretariat to continue to streamline the procedures, recognizing
that, while maintaining quality, the timeliness of their publication isparamount to fulfil the expected accomplishments approved in the
programme budget, and expecting that the report ought to be publishedwithin the same year in which it is approved.
20. The Committee recognized that, because of the need to maintain theintensity of its work and particularly to improve dissemination of its
findings, voluntary contributions to the general trust fund established by the
Executive Director of the United Nations Environment Programme toreceive and manage voluntary contributions to support the work of theCommittee would be beneficial. The Committee suggested that the General
Assembly might encourage Member States to consider making voluntary
contributions to the general trust fund for this purpose or to makecontributions in kind.
21. The Committee agreed to hold its sixty-first session in Vienna from26 to 30 May 2014.

5

6 UNSCEAR 2013 REPORT

Chapter III
Scientific findings
22. Two scientific annexes (published separately) provide the rationale forthe conclusions expressed in the present chapter.

A.

Levels and effects of radiation exposure due to the nuclear
accident after the 2011 great east-Japan earthquake andtsunami1.

The accident and the release of radioactive material into the environment
23. On 11 March 2011, at 14.46 local time, a 9.0-magnitude earthquake
occurred near Honshu, Japan, creating a devastating tsunami that left a trail
of death and destruction in its wake. The earthquake and subsequenttsunami, which flooded over 500 square kilometres of land, resulted in theloss of more than 20,000 lives and destroyed property, infrastructure andnatural resources. They also led to the worst civil nuclear disaster since theone at Chernobyl in 1986. The loss of off-site and on-site electrical powerand compromised safety systems at the Fukushima Daiichi nuclear power
station led to severe core damage to three of the six nuclear reactors on thesite; this resulted in the release, over a prolonged period, of very large
amounts of radioactive material into the environment.
24. As an immediate response, the Government of Japan recommended theevacuation of about 78,000 people living within a 20-km radius of the power
plant and the sheltering in their own homes of about 62,000 other people
living between 20 and 30 km from the plant. Later, in April 2011, theGovernment recommended the evacuation of about 10,000 more people
living farther to the north-west of the plant (referred to as the deliberate
evacuation area), because of the high levels of radioactive material on the
ground. The evacuations greatly reduced (by up to a factor of 10) the levelsof exposure that would otherwise have been received by those living in thoseareas. However, the evacuations themselves also had repercussions for thepeople involved, including a number of evacuation-related deaths and thesubsequent impact on mental and social well-being (for example, because
evacuees were separated from their homes and familiar surroundings, andmany lost their livelihoods).
25. The information reviewed by the Committee implies atmosphericreleases of iodine-131 and caesium-137 (two of the more significant
radionuclides from the perspective of exposures to people and theenvironment) in the ranges of 100 to 500 petabecquerels (PBq) and 6 to
20 PBq, respectively; for its further work, the Committee used estimates thatlie within those ranges. These estimates are lower, indicatively, by a factor of
about 10 and 5, respectively, than corresponding estimates of atmosphericreleases resulting from the Chernobyl accident. Winds transported a large
portion of the atmospheric releases to the Pacific Ocean. In addition, liquid
releases were discharged directly into the surrounding sea. The directdischarges amounted to perhaps 10 and 50 per cent of the corresponding
atmospheric discharges for iodine-131 and caesium-137, respectively; lowlevel releases into the ocean were still ongoing in May 2013.

REPORT TO THE GENERAL ASSEMBLY

2.

Dose assessment
26. Iodine-131 (with a short half-life of 8 days) and caesium-137 (with amuch longer half-life of 30 years) were found to be the two most importantradionuclides for dose assessment. For those two radionuclides, the affected
tissues and the time span of the exposure were quite different. Iodine-131
tended to accumulate in the thyroid gland for a few weeks after the releaseand delivered a dose primarily to that organ. Caesium-137 was deposited on
the ground; it delivers a dose to the whole body over many years following
the release.
27. The Committee has made estimates of the radiation exposures ofvarious categories of people, namely: members of the public exposed as aresult of the release of radioactive material into the environment;
occupationally exposed workers employed at the Fukushima Daiichi nuclear
power station at the time of the accident and those subsequently involved in
on-site recovery operations; and emergency personnel involved in on-site
and/or off-site activities. Where practicable, the Committee based its
evaluations on results of individual monitoring. Occupationally exposed
workers and emergency personnel were generally monitored for exposure tosources of radiation external to the body (external exposures) and for
exposures from intakes of radioactive materials into the body (internal
exposures) where these may have been significant.
28. At the time the Committee’s evaluation began, few direct
measurements of internal exposures were available for members of the
public. These were insufficient for the Committee to estimate doses for theareas in Japan most affected by the accident. Therefore, the Committee had
to rely on the use of various models to estimate doses on the basis ofmeasured, or predicted, levels of radioactive material in the environment andtheir transfer through the environment to humans (for example, the figure
illustrates the pattern — derived from measurements — of caesium-137
deposition in the areas of Japan most affected as a result of the accident). Of
necessity, modelling had to be used to forecast potential doses in the future.

7

8 UNSCEAR 2013 REPORT

FigureDeposition of caesium-137 on the ground in the Fukushima Prefecture andneighbouring prefectures based on measurement data adjusted to 14 June 2011
This map is derived by interpolating between measurements; its aim is
to portray the overall pattern of deposition levels and extent rather than toindicate precise demarcation areas.

29. The estimated effective doses resulting from the accident at the
Fukushima Daiichi nuclear power station can be put in perspective bycomparing them with those received from exposures to radiation sources ofnatural origin (such as cosmic rays and naturally occurring radioactive
material in food, air, water and other parts of the environment). The Japanesepeople receive an effective dose of radiation from naturally occurringsources of, on average, about 2.1 millisieverts (mSv) annually and a total of
about 170 mSv over their lifetimes. The Committee’s latest estimate for the
global average annual exposure to naturally occurring sources of radiation is
2.4 mSv and ranges between about 1 and 13 mSv, while sizeable populationgroups receive 10 to 20 mSv annually.4 Absorbed doses to individual organs
are expressed in milligrays (mGy). The average annual absorbed dose to thethyroid from naturally occurring sources of radiation is typically of the orderof 1 mGy.
__________________
4 Official Records of the General Assembly, Sixty-third Session, Supplement No. 46(A/63/46), table 1.

REPORT TO THE GENERAL ASSEMBLY(a)

Members of the public
30. The districts with the highest average estimated doses for members of
the public were within the 20-km evacuation zone and the deliberate
evacuation area. For adults, the effective dose estimated to have been
received before and during the evacuation was, on average, less than 10 mSv
and about half of that level for those evacuated early on 12 March 2011. The
corresponding estimated average absorbed dose to the thyroid was up to
about 35 mGy. For 1-year-old infants, the effective dose was estimated to beabout twice that for adults and the dose to the thyroid was estimated to be up
to about 80 mGy, as much as one half of which arose from the ingestion ofradioactivity in food. However, there was considerable variation between
individuals around this value, depending on their location and what foodthey consumed.
31. Adults living in the city of Fukushima were estimated to have received,on average, an effective dose of about 4 mSv in the first year following theaccident; estimated doses for 1-year-old infants were about twice as high.
Those living in other districts within the Fukushima Prefecture and inneighbouring prefectures were estimated to have received comparable or
lower doses; even lower doses were estimated to have been received
elsewhere in Japan. Lifetime effective doses (resulting from the accident)
that, on average, could be received by those continuing to live in the
Fukushima Prefecture have been estimated to be just over 10 mSv; thisestimate assumes that no remediation measures will be taken to reduce dosesin the future and, therefore, may be an overestimate. The most importantsource contributing to these estimated doses was external radiation from
deposited radioactive material.
32. Doses higher or lower than the average values above can be estimatedfor people with habits or behaviour significantly different from the average,
and/or for those living in areas where the levels of radioactive material wereor are significantly different from the average for a particular district orprefecture. Within a district the individual doses related to inhalation andexposure to external radiation typically range from about one third of theaverage up to three times the average. Larger doses cannot be totally
discounted for some individuals — in particular, if they consumed certain
locally produced foodstuffs in the aftermath of the accident despite
governmental advice or continued living in evacuation areas for an extended
period. Some infants may have received thyroid doses of 100 mGy or more.
33. Some information on internal doses, based on direct measurements ofradioactivity in people, was available shortly after the accident, but more
information became available after the Committee completed its dose
estimations. Collectively, these measurements of radioactive content of the
thyroid and of the whole body indicated doses due to internal exposure lower
than those estimated by the Committee, by a factor of about 3 to 5 forthyroid doses and up to about 10 for whole-body doses. Thus, the Committee
considers that its dose estimates may overestimate actual exposures.
34. Radiation exposures in neighbouring countries and the rest of the world
resulting from the accident were far below those received in Japan; effective
doses were less than 0.01 mSv, and thyroid doses were less than 0.01 mGy;these levels would be of no consequence for the health of individuals.

910 UNSCEAR 2013 REPORT(b)

Fukushima Daiichi nuclear power station workers, emergency
personnel, municipal workers and volunteers
35. By the end of October 2012, about 25,000 workers had been involved
in mitigation and other activities at the Fukushima Daiichi nuclear power
station site; about 15 per cent of them were employed directly by the plant
operator (Tokyo Electric Power Company (TEPCO)), while the rest were
employed by contractors or subcontractors. According to their records, theaverage effective dose of the 25,000 workers over the first 19 months after
the accident was about 12 mSv. About 35 per cent of the workforce received
total doses of more than 10 mSv over that period, while 0.7 per cent of theworkforce received doses of more than 100 mSv.
36. The Committee examined the data on internal exposure for 12 of themost exposed workers and confirmed that they had received absorbed doses
to the thyroid in the range of 2 to 12 Gy, mostly from inhalation of iodine131. The Committee also found reasonable agreement between its
independent assessments of effective dose from internal exposure and thosereported by TEPCO for those workers for whom there were measurable
levels of iodine-131 in the body. No account was taken of the potential
contribution from intakes of shorter-lived isotopes of iodine, in particulariodine-133; as a result, the assessed doses from internal exposure could havebeen underestimated by about 20 per cent. For many workers, because of thelong delay before monitoring, iodine-131 was not detected in their thyroids;
for those workers the internal doses estimated by TEPCO and its contractors
are uncertain.
37. Apart from those groups, in vivo monitoring of 8,380 personnel
affiliated with the United States Department of Defense was carried out
between 11 March 2011 and 31 August 2011. About 3 per cent of thosemonitored had measurable activity levels with a maximum effective dose of
0.4 mSv and a maximum absorbed dose to the thyroid of 6.5 mGy.

3.

Health implications
38. No radiation-related deaths or acute diseases have been observed
among the workers and general public exposed to radiation from theaccident.
39. The doses to the general public, both those incurred during the firstyear and estimated for their lifetimes, are generally low or very low. No
discernible increased incidence of radiation-related health effects are
expected among exposed members of the public or their descendants. The
most important health effect is on mental and social well-being, related tothe enormous impact of the earthquake, tsunami and nuclear accident, andthe fear and stigma related to the perceived risk of exposure to ionizing
radiation. Effects such as depression and post-traumatic stress symptoms
have already been reported. Estimation of the occurrence and severity ofsuch health effects are outside the Committee’s remit.
40. For adults in Fukushima Prefecture, the Committee estimates average
lifetime effective doses to be of the order of 10 mSv or less, and first-yeardoses to be one third to one half of that. While risk models by inference
suggest increased cancer risk, cancers induced by radiation are
indistinguishable at present from other cancers. Thus, a discernible increasein cancer incidence in this population that could be attributed to radiation
exposure from the accident is not expected. An increased risk of thyroid

REPORT TO THE GENERAL ASSEMBLY

cancer in particular can be inferred for infants and children. The number of
infants that may have received thyroid doses of 100 mGy is not known withconfidence; cases exceeding the norm are estimated by model calculations
only, and in practice they are difficult to verify by measurement.
41. For the 12 workers whose exposure data were scrutinized by theCommittee and who were estimated to have received absorbed doses to thethyroid from iodine-131 intake alone in the range of 2 to 12 Gy, an increased
risk of developing thyroid cancer and other thyroid disorders can be inferred.
More than 160 additional workers received effective doses currently
estimated to be over 100 mSv, predominantly from external exposures.
Among this group, an increased risk of cancer would be expected in the
future. However, any increased incidence of cancer in this group is expected
to be indiscernible because of the difficulty of confirming such a small
incidence against the normal statistical fluctuations in cancer incidence.
Workers exposed to doses above 100 mSv will be specially examined,
including through annual examinations of the thyroid, stomach, large
intestine and lungs for potential late radiation-related health effects.
42. In June 2011, a health survey of the local population (the Fukushima
Health Management Survey) was initiated. The survey, which began in
October 2011 and is planned to continue for 30 years, covers all 2.05 million
people living in Fukushima Prefecture at the time of the earthquake andreactor accident. It includes a thyroid ultrasound survey of 360,000 children
aged up to 18 years at the time of the accident, using modern high-efficiency
ultrasonography, which increases the ability to detect small abnormalities.
Increased rates of detection of nodules, cysts and cancers have been
observed during the first round of screening; however, these are to be
expected in view of the high detection efficiency. Data from similar
screening protocols in areas not affected by the accident imply that theapparent increased rates of detection among children in Fukushima
Prefecture are unrelated to radiation exposure.
4.

Radiation exposures and effects on non-human biota
43. Exposures of selected non-human biota in the natural environment
were also estimated. The doses and associated effects of radiation on nonhuman biota following the accident were evaluated against the Committee’s
previous evaluations of such effects.5 Exposures of both marine andterrestrial non-human biota following the accident were, in general, too low
for acute effects to be observed, though there may have been some
exceptions because of local variability:(a) Effects on non-human biota in the marine environment would be
confined to areas close to where highly radioactive water was released into
the ocean;(b) Continued changes in biomarkers for certain terrestrial organisms,
in particular mammals, cannot be ruled out, but their significance forpopulation integrity of those organisms is unclear. Any radiation effects
would be restricted to a limited area where the deposition of radioactive
material was greatest; beyond that area, the potential for effects on biota is
insignificant.

__________________
5 See Official Records of the General Assembly, Fifty-first Session, Supplement No. 46(A/51/46), and Sixty-third Session, Supplement No. 46 (A/63/46).

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44. While it was not within the scope of the Committee’s evaluation, it isimportant to note that the effects of the protective actions and any
remediation conducted to reduce human exposure have a significant impact
on, inter alia, environmental goods and services, resources used inagriculture, forestry, fisheries and tourism, and amenities used in spiritual,cultural and recreational activities.

B.

Effects of radiation exposure of children
45. Epidemiological studies reported in the literature vary with regard to
the specific age groups they consider. For the purposes of the Committee’s
evaluation of the effects of radiation exposure on children, the term
“children”, in contrast to “adults”, included those exposed as infants,
children and adolescents. The evaluation did not specifically address effects
of in utero exposure to radiation because such information is contained inother comprehensive reports. The evaluation also did not address the many
beneficial uses of radiation exposure for children, such as in medical
diagnosis and therapy, which are outside the mandate of the Committee.
46. Sources of exposure to children that are of particular interest include
accidental exposures, and specific regions with enhanced levels of natural
background radiation, as well as diagnostic and therapeutic procedures. The
data reviewed by the Committee were derived from studies covering a wide
range of doses, variable dose rates, whole and partial body exposure andchildren of different ages. The effects described in the annex are often very
specific to a given exposure scenario.
47. At its sixtieth session the Committee considered the effects of radiation
exposure of children and reached the following conclusions:(a) For a given radiation dose, children are generally at more risk oftumour induction than are adults. Cancers potentially induced by exposure toionizing radiation at young ages may occur within a few years, but also
decades later. In its report on its fifty-fourth session, the Committee statedthat estimates of lifetime cancer risk for those exposed as children wereuncertain and might be a factor of 2 to 3 times as high as estimates for a
population exposed at all ages.6 That conclusion was based on a lifetime risk
projection model combining the risks of all tumour types together;(b) The Committee has reviewed evolving scientific material andnotes that radiogenic tumour incidence in children is more variable than in
adults and depends on the tumour type, age and gender. The term “radiation
sensitivity” with regard to cancer induction refers to the rate of radiogenic
tumour induction. The Committee reviewed 23 different cancer types.
Broadly, for about 25 per cent of these cancer types, including leukaemia andthyroid, skin, breast and brain cancer, children were clearly moreradiosensitive. For some of these types, depending on the circumstances, therisks can be considerably higher for children than for adults. Some of thesecancer types are highly relevant for evaluating the radiological consequencesof accidents and of some medical procedures;(c) For about 15 per cent of the cancer types (e.g. colon cancer),children appear to have about the same radiosensitivity as adults. For about__________________
6 Official Records of the General Assembly, Sixty-first Session, Supplement No. 46 andcorrigendum (A/61/46 and Corr.1) paras. 21-22.

REPORT TO THE GENERAL ASSEMBLY

10 per cent of cancer types (e.g. lung cancer), children appear less sensitive
to external radiation exposure than adults. For about 20 per cent of cancer
types (e.g. oesophagus cancer), the data are too weak to draw a conclusion
regarding any differences in risk. Finally, for about 30 per cent of cancer
types (e.g. Hodgkin’s disease and prostate, rectum and uterus cancer), there
is only a weak relationship or none at all between radiation exposure andrisk at any age of exposure;(d) At present, projections of lifetime risk for specific cancer types
following exposure at young ages are statistically insufficient. Estimatescurrently do not adequately capture the known variations, and additional
studies are needed;(e) For direct effects that occur after high (either acute or
fractionated) doses (so-called deterministic health effects), the differences inoutcome between exposure in childhood and in adulthood are complex andcan be explained by the interaction of different tissues and mechanisms.
These effects may be seen after radiation therapy or following highexposures in accidents. The difference between the radiation sensitivity ofchildren and that of adults for deterministic effects in a specific organ isoften not the same as the difference for cancer induction. There are someinstances in which childhood exposure poses more risk than adulthood
exposure (e.g. risk of cognitive defects, cataracts and thyroid nodules). There
are other instances where the risk appears to be about the same (e.g. risk ofneuroendocrine abnormalities), and there are a few instances wherechildren’s tissues are more resistant (e.g. lungs and ovaries);(f) Because of all the above considerations, the Committee
recommends that generalizations on the risks of effects of radiation exposure
during childhood should be avoided. Attention should be directed to
specifics of the exposure, age at exposure, absorbed dose to certain tissues
and the particular effects of interest;(g) There have been many studies of possible heritable effects
following radiation exposure; such studies were reviewed by the Committee
in 2001. It has been generally concluded that no heritable effects in humans
due to radiation exposure have been explicitly identified (specifically instudies of offspring of survivors of the atomic bombings). Over the past
decade, there have been additional studies that have focused on survivors ofchildhood and adolescent cancer following radiotherapy, where gonadal
doses are often very high. There is essentially no evidence of an increase inchromosomal instability, minisatellite mutations, transgenerational genomic
instability, change in sex ratio of offspring, congenital anomalies orincreased cancer risk in the offspring of parents exposed to radiation. One
reason for this is the large fluctuation in the spontaneous incidence of theseeffects;(h) Health effects and risks are dependent on a number of physicalfactors. Because children have smaller body diameters and there is lessshielding by overlying tissues, the dose to their internal organs will be larger
than for an adult for a given external exposure. Because they are also shorter
than adults, children may receive a higher dose from radioactivity distributedin and deposited on the ground. These factors are important when
considering doses to populations in some areas with high levels ofradionuclides in and on the ground. In diagnostic medical exposure, children
may receive significantly higher doses than adults for the same examination

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if the technical parameters for delivering the dose are not specifically
adapted;(i) Regarding internal exposure, because of the smaller size of
infants and children, and thus because their organs are closer together,radionuclides concentrated in one organ irradiate other organs of children’sbodies more than occurs in adults. There are also many other age-related
factors involving metabolism and physiology that make a substantial
difference in dose at different ages. Several radionuclides are of particularconcern regarding internal exposure of children. Accidents involving
releases of radioactive iodines (for example, in a nuclear power plant
accident) can be significant sources of exposure of the thyroid gland, andthus have the potential to induce thyroid cancer. For a given intake, the doseto the thyroid for infants is eight or nine as large as that for adults. For
intakes of caesium-137, there is very little difference in dose between
children and adults. Internal exposure of children also occurs in the medical
use of radionuclides. The spectrum of procedures normally performed onchildren is different from that performed on adults. Potentially higher doses
in children are offset in practice by the use of a lower amount ofadministered radioactive material.
48. The Committee recognizes that continued research is needed to identify
the full scope and expression of the differences in effects, mechanisms andrisk from exposure to ionizing radiation for children and for adults. This isnecessary because for a number of studies (such as of the atomic bombing
survivors, children exposed to radioiodine after the Chernobyl accident andthose who have had computed tomography scans), the lifetime results remain
incomplete. Future long-term studies following childhood exposure will facesignificant difficulties owing to unlinked health records, administrative andpolitical barriers and ethical and privacy considerations.
49. Important areas of future research and work also include evaluation ofpotential radiation effects for children: (a) in areas of high natural
background exposure; (b) after high-dose medical procedures involving
interventional fluoroscopy; and (c) after cancer radiotherapy (including
evaluation of potential interactions with other therapies). The Committee has
identified the following areas for future research as well: development of
databases on radiation doses for children who can be tracked in the longterm; and evaluation of effects following whole and partial irradiation ofjuvenile organs. Studies at the molecular, cellular, tissue and juvenile animallevel are potentially informative.

REPORT TO THE GENERAL ASSEMBLY

15

Appendix I
Members of national delegations attending the fifty-eighth to
sixtieth sessions of the United Nations Scientific Committee on
the Effects of Atomic Radiation
Argentina

A. J. González (Representative), A. Canoba, M. di Giorgio

Australia

C. M. Larsson (Representative), C. Baggoley, G. Hirth,
S. B. Solomon, R. Tinker

BelarusJ. Kenigsberg (Representative), A. Stazharau, V. Ternov

Belgium

H. Vanmarcke (Representative), S. Baatout, H. Bijwaard,
H. Bosmans, G. Eggermont, H. Engels, F. Jamar,
L. Mullenders, H. Slaper, P. Smeesters, A. Wambersie,
P. Willems

BrazilJ. Hunt (Representative), D. R. Melo (Representative),
M. Nogueira Martins (Representative), M. C. Lourenço,
L. Holanda Sadler Veiga

CanadaC. Purvis (Representative), B. Pieterson (Representative),
N. E. Gentner (Representative), D. Boreham, K. Bundy,
D. B. Chambers, J. Chen, S. Hamlat, R. Lane, C. Lavoie,
E. Waller

China

Pan Z. (Representative), Chen Y., Du Y., Gao H., Liu J.,
Liu S., Pan S., Su X., Sun Q., Wang Y., Yang H., Zhang W.,
Zhu M.

Egypt

T. S. El-Din Ahmed (Representative), M.A.M. Gomaa(Representative)

Finland

S. Salomaa (Representative), A. Auvinen, E. Salminen

FranceL. Lebaron-Jacobs (Representative), A. Rannou(Representative), E. Ansoborlo, M. Bourguignon,
J.-R. Jourdain, F. Ménétrier, M. Tirmarche

Germany

W. Weiss (Representative), A. A. Friedl, K. Gehrcke,
P. Jacob, T. Jung, G. Kirchner, J. Kopp, R. Michel,
W. U. Müller

India

K. B. Sainis (Representative), B. Das, P. C. Kesavan,
Y. S. Mayya, K. S. Pradeepkumar

Indonesia

S. Widodo (Representative), Z. Alatas, G. B. Prajogi,
G. Witono, B. Zulkarnaen

Japan

Y. Yonekura (Representative), S. Akiba, T. Aono, N. Ban,
M. Chino, K. Kodama, M. Kowatari, M. Nakano, O. Niwa,
K. Ozasa, S. Saigusa, G. Suzuki, T. Takahashi, Y. Yamada,
H. Yamagishi

MexicoJ. Aguirre Gómez (Representative)

Pakistan

M. Ali (Representative), Z. A. Baig

Peru

A. Lachos Dávila (Representative), B. M. García Gutiérrez

16 UNSCEAR 2013 REPORT

PolandM. Waligórski (Representative), L. Dobrzyński, M. Janiak,
M. Kruszewski

Republic of Korea

K.-W. Cho (Representative), S. H. Na (Representative),
K.-H. Do, D.-K. Keum, J.-I. Kim, J. K. Lee, S. Y. Nam

RussianFederation

M. Kiselev (Representative), A. Akleyev, R. Alexakhin,
T. Azizova, V. Ivanov, N. Koshurnikova, A. Koterov,
I. Kryshev, B. Lobach, O. Pavlovskiy, A. Rachkov,
S. Romanov, A. Sazhin, S. Shinkarev

Slovakia

E. Bédi (Representative), M. Chorváth, Ž. Kantová,
K. Petrová, L. Tomášek, I. ZachariášováSpain

M. J. Muñoz González (Representative), M. T. Macías
Domínguez, B. Robles Atienza, E. Vañó Carruana

Sudan

M.A.H. Eltayeb (Representative), I. Salih Mohamed Musa
(Representative), E.A.E. Ali (Representative)

SwedenL. Hubbard (Representative), L. Moberg (Representative),
A. Almén, L. Gedda, J. Johansson Barck-Holst

UkraineD. Bazyka (Representative)

United Kingdomof Great Britain
and Northern
Ireland

J. Harrison (Representative), J. Cooper (Representative),
S. Bouffler, J. Simmonds, R. Wakeford

United States ofAmerica

F. A. Mettler Jr. (Representative), L. R. Anspaugh,
J. D. Boice Jr., N. H. Harley, E. V. Holahan Jr.,R. J. Preston

REPORT TO THE GENERAL ASSEMBLY

Appendix II
Scientific staff and consultants cooperating with the United
Nations Scientific Committee on the Effects of Atomic Radiationin the preparation of its scientific report for 2013
G. N. Kelly
V. Golikov
L. S. Constine
H. D. Nagel
D. Nosske
R. Shore

Secretariat of the United Nations Scientific Committee on the
Effects of Atomic Radiation
M. J. Crick
F. Shannoun
H. Yasuda (seconded)17