UNSCEAR

United Nations Scientific Committee
on the Effects of Atomic Radiation

DEVELOPMENTS SINCE THE 2013 UNSCEARREPORT ON THE LEVELS AND EFFECTS OF
RADIATION EXPOSURE DUE TO THE NUCLEAR
ACCIDENT FOLLOWING THE GREAT EAST-JAPAN
EARTHQUAKE AND TSUNAMI
A 2017 white paper to guide the Scientific Committee’s
future programme of work

EVALUATING RADIATION SCIENCE FOR INFORMED DECISION-MAKING

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORTON THE LEVELS AND EFFECTS OF RADIATIONEXPOSURE DUE TO THE NUCLEAR ACCIDENTFOLLOWING THE GREAT EAST-JAPAN
EARTHQUAKE AND TSUNAMI
A 2017 white paper to guide the Scientific Committee’s
future programme of work

UNITED NATIONSNew York, 2017

This document is available on the UNSCEAR website at www.unscear.org.
Any inquiries regarding this document should be sent to the UNSCEAR secretariat (unscear@unscear.org).

The views expressed herein are those of the authors and editors and do not necessarily reflect the views of theUnited Nations.

© 2017. United Nations for the English edition.
© 2017. United Nations for the Japanese edition prepared by BLC Corporation, Osaka, Japan.
All worldwide rights reserved.
This publication has not been formally edited.

CONTENTS
EXECUTIVE SUMMARY ......................................................................................................... v
I.

INTRODUCTION ................................................................................................................ 1

II.

EVALUATION OF NEW INFORMATION ....................................................................... 2

III. UPDATES ON RADIONUCLIDE RELEASES TO ATMOSPHERE,DISPERSION AND DEPOSITION...................................................................................... 4
IV. UPDATES ON RADIONUCLIDE RELEASES TO WATER, DISPERSION
AND DEPOSITION .............................................................................................................. 8V.

UPDATES ON THE TRANSFER OF RADIONUCLIDES INTERRESTRIAL AND FRESHWATER ENVIRONMENTS ............................................ 11

VI. UPDATES ON EVALUATION OF DOSES FOR THE PUBLIC..................................... 16VII. UPDATES ON EVALUATION OF DOSES FOR WORKERS ........................................ 22
VIII.UPDATES ON HEALTH IMPLICATIONS FOR WORKERS AND
PUBLIC .............................................................................................................................. 25
IX. UPDATES ON EVALUATION OF DOSES AND EFFECTS FOR NONHUMAN BIOTA................................................................................................................. 31
X. CONCLUSIONS OF APPRAISAL OF NEW PUBLICATIONS ...................................... 34
XI. COLLECTION AND EVALUATION OF MAJOR RESEARCH PROJECTSAND PROGRAMMES ....................................................................................................... 36
ACKNOWLEDGEMENTS ....................................................................................................... 39
REFERENCES ........................................................................................................................... 41

Attachment: Summary of the main outcomes of meetings with the Japanese research community
The attachment cited in this white paper is electronically available for download in English
only from http://www.unscear.org/unscear/en/publications/Fukushima_WP2017.html

iii

EXECUTIVE SUMMARY
This summary is based on the report of the United Nations Scientific Committee on the Effects ofAtomic Radiation to the seventy-second session of the United Nations General Assembly.1[…]
At its sixty-fourth session (29 May to 2 June 2017), the Committee recalled its
assessment of the exposures and effects due to the nuclear accident after the 2011 great eastJapan earthquake and tsunami, as presented in its report to the sixty-eighth General Assemblyin 2013 2 and the supporting detailed scientific annex. 3 It had concluded in that report that, ingeneral, doses were low and that therefore associated risks were also expected to be low. A
discernible increase in cancer incidence in the adult population of Fukushima Prefecture that
could be attributed to radiation exposure from the accident was not expected. Nevertheless, thereport noted a possibility that an increased risk of thyroid cancer among those children most
exposed to radiation could be theoretically inferred, although the occurrence of a large numberof radiation-induced thyroid cancers in Fukushima Prefecture—such as occurred after the
Chernobyl accident—could be discounted because absorbed doses to the thyroid after theaccident at Fukushima were substantially lower. It had also concluded that no discernible
changes in birth defects and hereditary diseases were expected and that any increased incidenceof cancer among workers due to their exposure was expected to be indiscernible because of the
difficulty of confirming a small increase against the normal statistical fluctuations in cancer
incidence. The effects on terrestrial and marine ecosystems were expected to have beentransient and localized.
Following its assessment, the Committee put in place arrangements for follow-up
activities to enable it to remain abreast of additional relevant information as it was published.
The Committee’s reports of the sixty-second and sixty-third sessions to the seventieth andseventy-first sessions of the General Assembly, respectively, included the Committee’sfindings from its follow-up activities up to the relevant time in each case.
The Committee has continued to identify further information that had become available
up to the end of 2016, and systematically appraised relevant new publications to assess theirimplications for the Committee’s 2013 report. A large proportion of these new publications
have again confirmed the main assumptions and findings of the Committee’s 2013 report.
None of the publications have materially affected the main findings in, or challenged the major
assumptions of, the Committee’s 2013 report. A few have been identified for which further
analysis or more conclusive evidence from additional research is needed. On the basis of thematerial reviewed, the Committee sees no need, at the current time, to make any change to its
assessment or its conclusions. However, several of the research needs identified by theCommittee have yet to be addressed fully by the scientific community.
The Committee has requested that the findings be issued electronically on its website asa non-sales publication in English and that, subject to available resources, its publication be
fostered in Japanese.
1

Official Records of the General Assembly, Seventy-second session, Supplement No. 46 (A/72/46).
Official Records of the General Assembly, Sixty-eighth session, Supplement No. 46 and corrigendum (A/68/46
and Corr.1).
3
Sources, Effects and Risks of Ionizing Radiation: United Nations Scientific Committee on the Effects of Atomic
Radiation 2013 Report to the General Assembly, vol. I, annex A (United Nations publication, Sales No. E.14.IX.1).
2

v

I.

INTRODUCTION

1.
The Committee had assessed radiation exposures of the public, workers and non-humanbiota that resulted from the 11 March 2011 accident at the Fukushima Daiichi nuclear power
station (FDNPS), considered the health implications, and presented its findings in its annual
report to the United Nations General Assembly in August 2013. 4 The United Nations
subsequently published the Committee’s findings and the detailed scientific annexes
underpinning them on 2 April 2014 [U2]. The publication (referred to hereafter as the “2013report”) was well received by the General Assembly, governments, the scientific community
and the media/public in Japan.
2.
The Committee’s assessment had, in general, been based on information disclosed or
published before the end of October 2012. Subsequently, much additional relevant information
has been published or become available and this is likely to continue for the foreseeable future.
The Committee has remained abreast of such developments because they may have
implications for the results of its assessment (for example in corroborating, challenging or
refining its findings and/or contributing to addressing identified research needs) and intends tocontinue to do so; this will enable the Committee to take informed and timely decisions on theneed to refine or update its previous findings. The Committee expects that providing soundscientific appraisal of new material will also help (a) those affected by the accident to better
understand the situation and (b) inform decision-making.
3.
Accordingly, at its sixty-first session (21–25 July 2014), the Committee had requested
the secretariat to “submit for consideration at its sixty-second session (1–5 June 2015)preliminary plans […] for follow up activities to update and consolidate some of the findings
and conclusions of the Committee’s assessment of the radiological consequences of the
Fukushima Daiichi accident”. It also asked the secretariat to “promptly develop a standing
mechanism to stay aware of new scientific developments in the follow-up to the accident. Thatmechanism should be based on the ad hoc arrangements that had been developed for
conducting its recent assessment of the accident”. It also asked the secretariat to “reportannually on the implications for the Committee’s programme of work”.
4.
In response, the secretariat developed a project plan of follow-up activities, which wasendorsed by the Committee and is being implemented. The project comprises two phases:
Phase I, a systematic and ongoing review of new information; and Phase II, an update of the2013 report at an appropriate time. The overall aim of Phase I (up to at least 2016 and beyond)is to “keep the Committee regularly apprised of the implications of new publications andresearch activities related to the accident with a view to initiating a formal update of the 2013
report (i.e. Phase II) at an appropriate time”. The more specific objectives of Phase I include:(a) To systematically keep the overall radiological situation on the FDNPS accident
under review by collecting and appraising published information;(b) To collect and evaluate progress made in, and plans for, major research projects andprogrammes related to pending questions;4

Official Records of the General Assembly, Sixty-eighth session, Supplement No. 46 and corrigendum (A/68/46
and Corr.1).

1

2

2017 WHITE PAPER(c)
To promptly identify inconsistencies between information issued after October 2012
and the 2013 report;(d) To conduct ad hoc analyses to help clarify the situation and which could be usedsubsequently in any update of the 2013 report;(e)

To respond to questions and critiques of the 2013 report;(f)
To report annually to the Committee at its regular sessions on the outcomes of theabove.
5.
At its sixty-second session, the Committee agreed to the publication of a white paper 5
setting out: (a) an assessment of the implications of new scientific developments (up till theend of 2014) for the findings of the 2013 report; and (b) a commentary on general themes
raised in the few critiques made of the 2013 report. In addition, two electronic attachments
were made available providing additional technical information that supplemented the 2013
report. This first white paper was published in October 2015 [U4]. At its sixty-third session,
the Committee agreed on the publication of a second white paper setting out a further
assessment of the implications of new scientific developments (since the first white paper and
up to the end of 2015) for the findings of the 2013 report. This second white paper was
published in October 2016 [U5].
6.
This third white paper sets out a further assessment of the implications of new scientificdevelopments (since the second white paper and up to the end of 2016) 6 for the findings of the2013 report. It provides a summary of the main outcomes of the follow-up activities that
underpin the findings reported by the Committee to the General Assembly. As before, thewhite paper includes reviews of published information, but (further to specific objective (b) inparagraph 4 above) it also includes a summary of major relevant research projects andprogrammes underway in Japan. The white paper provides an overview of the aims of theseprojects and programmes and when they are expected to provide information of particularvalue to any update of the 2013 report.

II.

EVALUATION OF NEW INFORMATION

7.
The scope of new information analysed by the Committee in its first white paper was,in general, restricted to publications in English in peer-reviewed journals that had not been
included or referenced in the 2013 report (i.e. published after October 2012, the cut-off datethat had been generally adopted for information analysed in the report), but which had become
available or published before the end of 2014. The second white paper covered information notpreviously considered that had become available or published before the end of 2015. This
third white paper covers information not previously considered that became available or was
published before the end of 2016. The scope of both the second and this white paper was
extended to include not only publications in peer-reviewed journals, but also peer-reviewed
conference papers, reports issued by regional/national institutes/organizations, government
5White papers are documents developed for the Committee to guide its future programme of work and that theCommittee has decided to share with the wider community.
6
Publications considered for this white paper comprised those which had not been reviewed in the previous white
papers and which had become available up to the end of 2016, including publications which had been made available
online. This white paper therefore includes some publications with an earlier publication date than 2016 and somewith a final publication date in 2017.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 3

departments/ministries, learned societies, utilities, and similar bodies, 7 reports issued byintergovernmental organizations, and major compilations 8 (and/or analyses) of data from official
and other sources. In practice, in preparing this white paper, only one publication was identified
for review from these additional categories: a report by the Science Council of Japan [S9].
8.
The approach the Committee used to identify, screen and appraise new information was
as described in the first white paper, with the exception of the introduction of an additional
topical area, that of transfer through the terrestrial and freshwater environments (as in thesecond white paper). In screening potentially relevant publications and selecting those thatshould be subject to more detailed appraisal, particular consideration was given to whether the
publication had the potential to:− Challenge 9 or confirm the assumptions in the 2013 report;− Affect the main findings of the 2013 report; or− Address research needs either identified in the 2013 report or in topical areas where awide consensus was emerging.
While all publications meeting the above criteria have been appraised, the content of this white
paper has a greater focus on new information that may potentially challenge the assumptions
and main findings of the 2013 report, rather than on new information which confirms theseassumptions and main findings. It also highlights some of the more relevant information which
has become available that addresses identified research needs and would be valuable to any
future assessment of the radiological impacts of the accident at FDNPS. However, it is notintended to provide a comprehensive overview of all new information relating to the FDNPS
accident.
9.
The following chapters describe the main outcomes of the screening and appraisal of
new sources of information for each topical area in turn. In each case, a brief recapitulation isprovided of the findings of the 2013 report, because these provide the context for the review, as
well as of the conclusions of the previous white papers. This is followed by a summary of theoutcomes of the appraisals, and conclusions about the implications both for the 2013 report andany follow-up activities. Chapter X then sets out overall conclusions from the appraisals andincludes a tabular summary of those sources of new information deemed to make a significant
contribution to addressing identified research needs. Finally, chapter XI summarizes major
relevant research projects and programmes underway in Japan and is supported by anelectronic attachment.
7

In exceptional cases, the scope was extended to scientific reports issued by non-governmental organizations.
Large amounts of data continue to be generated and published at relatively frequent intervals by various
Japanese organizations, and it would not be practicable to include all of these for review within this project.
Consideration has, therefore, been limited to more substantive compilations of data that have the potential to be
useful in the context of any future re-assessment or in extending the scope of any such re-assessment.
9
A publication would be considered to challenge an assumption in the 2013 report or materially affect its
conclusions if its implications were sufficient to warrant the Committee considering issuing an addendum to the2013 report.
8

42017 WHITE PAPER

III. UPDATES ON RADIONUCLIDE RELEASES TO ATMOSPHERE,DISPERSION AND DEPOSITIONA.

Recapitulation of the 2013 report

10.
The Committee had reviewed estimates of total releases to the atmosphere of 131I and137
Cs (the two most significant radionuclides from the perspective of exposures of people andthe environment). These estimates had ranged generally from 100 to 500 petabecquerels (PBq)
for 131I and from 6 to 20 PBq for 137Cs. The averages of the published estimates were about
10% and 20%, respectively, of the corresponding releases to the atmosphere estimated for the
Chernobyl accident. Much of the released material was dispersed over the Pacific Ocean, but,depending on the meteorological conditions, a fraction was dispersed over eastern mainland
Japan, and radioactive material was deposited on the ground by means of (a) dry deposition,and (b) wet deposition with rain, fog and snow. The main deposition on land occurred to thenorth-west of the FDNPS site, but significant deposition also occurred to the north, south andwest of the FDNPS site.
11.
In general, the Committee had relied on measurements of the deposition densities ofradionuclides as the basis for its estimates of doses to the public from external exposure andfrom inhalation. However, where measurement data were unavailable for the periods when
exposures occurred (e.g. for evacuees) and could no longer be obtained, the Committee had
needed to use an estimate of the source term (including the temporal patterns of release rates)
together with appropriate atmospheric transport, dispersion and deposition modelling (ATDM)
to estimate levels in the environment and resulting doses to people. The Committee had chosena published source term for this purpose [T7]. The releases of the radiologically dominantradionuclides 131I and 137Cs in this source term were 120 and 8.8 PBq, respectively. While at thelower end of the range of published estimates, and possibly an underestimate of the total release,
the Committee had considered this source term as the most appropriate for estimating doses
incurred as a result of dispersion over the land mass of Japan (see paragraphs B15–B16 in [U2]).
B.

Findings of review of new publications

12.
The first and the second white papers concluded that no publications had been
identified in this area that materially affected the main findings or challenged the major
assumptions of the 2013 report; several publications confirmed the assumptions in whole orpart. One publication [K4] was identified which provided a refinement of the source term
estimate used in the 2013 report, and the Committee recommended the use of this source termin preference in future studies, although its use was not expected to alter significantly the doses
estimated in the 2013 report. The Committee noted that new data that were becoming available
had the potential to significantly improve source term estimates and estimates of the levels ofradionuclides in the air and deposited on the ground. A detailed comparison of these new datawith those used in the 2013 report would be needed to fully understand their implications.
13.
Of the publications considered in this third white paper, 28 were reviewed in detail.
Many confirmed the assumptions and findings of the 2013 report in whole or in part. The main
implications of the findings of these publications are summarized below.
14.
Chino et al. [C2] identified which reactor units were the dominant sources ofatmospheric releases at different times during the major release period of 12–21 March 2011.
They also determined which reactor unit was the source of releases that resulted in deposition

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 5

on to specific areas of the Japanese mainland. The findings were based on 134Cs:137Cs activity
ratios derived from deposition density measurements, and information about the ratios in thefuel of the different reactor units. The study was not able to identify definitively which eventsat FDNPS resulted in large releases, but emphasized the scientific value of improved
understanding of this issue and the need for further collaborative research work in this area. A
similar approach has also been presented by Jäckel et al. [J1] using data to the north-west of
FDNPS and Snow et al. [S10] who added 135Cs:137Cs activity ratios observed in the south-westof FDNPS. Radionuclide deposition densities very close to (within 500 m of) FDNPS were
found to be dominated by contributions from reactor unit 2, whereas deposition densities atgreater distances towards the north and west were found to be more dominated by contributions
from reactor units 1 and 3. All three reactor units were found to contribute to the deposition
densities at greater distances towards the south-west.
15.
Furthermore, based on the above analysis, Chino et al. [C2] presented a minor update of
the Katata et al. [K4] source term relating solely to the period of 20 March to 21 March 2011.
They estimated a slightly lower release of 137Cs over this period compared to the previous
estimate, but little change in the total amount of 137Cs released. This small change to the Katata
et al. source term should be taken into account in future studies.
16.
Yumimoto et al. [Y10] used the source term originally estimated by Terada et al. [T7] toderive a new source term estimate using inverse modelling and a large set of deposition density
monitoring data recorded by aircraft. The authors then compared predicted concentrations of137
Cs in air using this source term with those measured by collection of suspended particulatematter on filter tape [O13, T12]. Yumimoto et al. were better able to reconstruct ground level
concentrations in air than previous studies, especially for 15 March 2011.
17.
Hanna and Young [H1] summarized briefly the current state-of-the-art techniques for
identifying the locations and/or magnitude of releases to atmosphere based on observations andmodelling of wind fields and atmospheric transport. They recommended that the researchcommunity across many disciplines should move towards harmonization of methodologies andterminologies via outreach to organizations that can influence the direction of public policy on
science. They proposed that special issues on source term estimation could be organized inpeer-reviewed journals with the goal of harmonizing methods, and that special sessions atscientific conferences could be organized on this topic.
18.
Girard et al. [G2] analysed the impact of uncertainties of model input and model
parameters on the predictions of atmospheric dispersion models. They used an estimate of therelease to atmosphere from the FDNPS accident to study the influence of uncertain model
inputs on gamma dose rates estimated using a Eulerian atmospheric transport, dispersion anddeposition model. They carried out a variance-based sensitivity analysis to understand which
input parameters had the greatest influence on estimates of gamma dose rates. The results
underline the need for further research to understand the influence of input uncertainty anduncertainty propagation through atmospheric dispersion modelling.
19.
The Science Council of Japan [S9] evaluated and compared several models used toanalyse the transportation and deposition of radioactive materials released during the FDNPS
accident. The inter-comparison covered regional-scale and global-scale atmospheric transport,
dispersion and deposition models as well as ocean dispersion models. One of the findings wasthat deposition of 137Cs on to the mainland of Japan, as assessed with different regional-scalemodels, was about 27±10% of the total emission. The global-scale model comparison indicatedthat wet deposition over the globe was 93±5% of the total 137Cs emissions assumed in themodels. The models considered were found to be capable of depicting the main features of62017 WHITE PAPER

observed radioactive material distributions. All of these findings are consistent with theassumptions and findings of the 2013 report.
20.
Fujiwara [F1] confirmed the feasibility of retrospectively reconstructing deposition
densities of 131I from the measured deposition densities of 129I, as had been presented earlier by
Muramatsu et al. [M13]. While Muramatsu et al. had applied their approach for the area within
80 km of FDNPS, where the concentrations of the two iodine radionuclides in soil were foundto be strongly correlated, the new study demonstrated that this approach—with somemodifications—was also feasible in areas far from FDNPS, where deposition densities of 131I
and 129I were relatively low.
21.
Hirose [H7] reviewed the information available on releases of radionuclides from the
FDNPS accident to the atmosphere and to the ocean and their subsequent transport, dispersion
and deposition based on many papers published between 2011 and 2016. The author confirmed
several of the assumptions and key findings of the 2013 report and the 2015 and 2016 white
papers. For example, he concluded from several publications that about 80% of the total
atmospheric release of 137Cs deposited on to the North Pacific Ocean. He also confirmed thevalue of the Tsuruta et al. [T12] publication (which presented 137Cs concentrations in air at
ground-level in the Fukushima and Kanto area derived from an analysis of filter-tapes of air
pollution monitoring stations). From a review of several publications, Hirose suggested that theparticle size of the 131I bearing particles may have differed from those bearing radiocaesium,and therefore that the dispersion and deposition behaviour of 131I bearing particles may havediffered from those bearing 134Cs and 137Cs. While the assumption in the 2013 report had beenthat particulate iodine and caesium behaved in a similar way during the atmospheric transportand deposition, the effects of any differences in particle size suggested by Hirose are likely tobe small compared with those due to assumptions about the chemical form of radioiodine (see[U5], paragraphs 15–16).
22.
Hirose [H6] investigated the monthly 137Cs deposition at monitoring stations in the
Kanto and south Tōhoku regions. The author concluded from the results that emissions ofradioactive material from FDNPS to atmosphere still continued in spring 2013, although the137
Cs emission rates were about four orders of magnitude smaller than during the initial release.
Steinhauser et al. [S11] have pointed out that secondary releases of radioactive materials are
possible—even years after the accident—because of decommissioning and dismantling
activities on the FDNPS site. This possibility was not discussed as an alternative explanation
for the monitoring results presented by Hirose. Steinhauser et al. further noted, as have Igarashi
et al. [I2] and Ochiai et al. [O1], that resuspension can lead to continuing concentrations of137
Cs in air and its re-deposition.
23.
Ochiai et al. [O1] studied the resuspension of caesium deposition in the years after theaccident. They showed that coarse and fine 137Cs-bearing particulates have different origins
and behaviours in the resuspension process. The authors introduced a new resuspension factor
that was a little smaller than the annual mean resuspension factors observed after the
Chernobyl accident in Europe. The study confirmed the assumption made in the 2013 reportthat resuspension did not significantly contribute to the long-term exposure of the public.
24.
Mikami et al. [M5] measured deposition densities and activity ratios of 110mAg, 134Cs
137
and Cs at a large number of locations across Fukushima Prefecture and several neighbouring
prefectures. They confirmed that deposition densities of 110mAg were several orders ofmagnitude smaller than those of 134Cs and 137Cs. The authors found that there was little change
in 134Cs and 137Cs deposition densities between March and December 2012, indicating that
there was little migration of radiocaesium deposited on to the soil, especially in a horizontal

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 7

direction, although this may be because of the topography of the selected measurement
locations (open and flat terrain). They also reported on spatial variations in the ratio 134Cs:137Cs,
which they attributed to multiple releases with different nuclide ratios. Such data on 134Cs:137Cs
ratios have been used by Chino et al. [C2] for linking deposition in specific areas with releases
from the different reactor units.
25.
Sato et al. [S6] demonstrated that the concentration of radiocaesium in soil varied
greatly within a small area: the average ratio (over 27 locations) of the maximum to theminimum measured concentration in five soil samples from an area 7 m by 7 m was about five.
Such information about spatial variability can improve understanding of the relationshipbetween measured concentrations in soil samples and estimated doses to the public.
26.
Satou et al. [S7] reported that they had isolated four radioactive solid particles fromsurface soil taken from a site 20 km north-west of FDNPS. According to the authors, theseparticles were larger and more radioactive than—but had similar chemical composition to—
those observed in previous studies [A1, A2, Y1]. These previous studies found caesiumbearing particles which consisted of water-insoluble “glassy spherules”, several micrometres indiameter, containing the elements caesium, oxygen, iron and zinc (Satou et al. and Yamaguchi
et al. both additionally found silicates in the caesium-bearing particles). In contrast, Kaneyasu
et al. [K2] reported that radiocaesium was attached to sulphate aerosols of submicron size andsoluble in water. Abe et al. [A1] concluded that such particles may originate from the nuclear
fuel, whereas Salbu and Lind [S4] argued that the absence of long-lived gamma-emitting
refractory fission products and the absence of transuranic elements indicated that the particles
could not have originated from spent nuclear fuel. One explanation for these differences might
be that the physical and chemical forms of the radiocaesium emitted during the FDNPS
accident varied considerably. This explanation is supported by Miyamoto et al. [M7] who
found three peaks at less than 0.5, 0.94 and 7.8 micrometres in the distribution of the activity
median aerodynamic diameter for 134Cs and 137Cs. More research is needed to fully understandthe physical and chemical properties of the caesium-bearing particles and aerosols released,because these properties will influence deposition processes, estimates of inhalation doses andthe future behaviour of radiocaesium in the environment.
27.
Sakaguchi et al. [S1] performed measurements of 236U, plutonium isotopes, and 134Cs
and 137Cs in samples of black-coloured road dusts from high radiation areas in Fukushima
Prefecture (at distances between 3 and 35 km from FDNPS). They found very highconcentrations of 134Cs and 137Cs in all samples and detected 239+240Pu and 236U at low levels.
According to the authors, the observed activity ratios for 236U:239+240Pu indicated that trace
amounts of uranium and plutonium were released from the fuel cores. They also estimated that
3.9 × 106 Bq of total uranium and 2.3 × 109 Bq of 239+240Pu were released in total from FDNPS.
This is consistent with the finding of the 2013 report that the fractional releases of plutonium
and uranium were many orders of magnitude smaller than those of the volatile elements
caesium and iodine.
28.
Terasaka et al. [T8] estimated concentrations of different radionuclides in air in theearly stage of the FDNPS accident for six locations in Ibaraki Prefecture from pulse height
distributions measured with thallium-doped sodium iodide (NaI(Tl)) scintillation detectors.
This work is similar to a previous study by Hirayama et al. [H4], who assessed the time
distribution of 131I concentration in air from measurements made at several monitoring posts inFukushima Prefecture. Further analysis is required to judge whether the Terasaka et al. study
confirms the findings of the 2013 report.

82017 WHITE PAPER

C.

Potential implication of new publications

29.
The Committee has noted the continuing progress being made in understanding thereleases to the atmosphere, including particle sizes and the releases of radionuclides other thanisotopes of iodine and caesium. New data and analyses are also continuing to improve
estimates of the levels of radionuclides in the air and deposited on the ground. The Committee
does not expect the new information to have significant implications for the findings of the2013 report, but this would need to be confirmed by more detailed analysis. 10
30.
The Committee has identified that research in the following specific areas would have thegreatest potential to contribute to addressing the needs identified in the 2013 report:(a) Continuing to investigate the modelling of wet deposition in atmospheric transportand dispersion models;(b) Investigating the influence of input uncertainty and uncertainty propagation throughatmospheric dispersion modelling;(c)Continuing to improve inverse and reverse modelling to estimate the source term;(d) Improving current estimates of the source term making use of all available
measurement data;(e) Continuing to use all available measurement data and ATDM to improveunderstanding of how the time distribution of release rates relates to events in the different
FDNPS reactor units;(f) Extending the reconstruction of 131I deposition from 129I measurements to theremaining soil samples;(g) Extending the measurements of radionuclide concentrations on filter tapes from air
quality monitoring stations to the remaining filter samples;(h) Analysing and comparing the data on 131I, 134Cs and 137Cs concentrations in air
against existing previous monitoring and modelling results;(i) Continuing to investigate the physical and chemical properties of caesium-bearing
particles and aerosols deposited after the FDNPS accident.

IV. UPDATES ON RADIONUCLIDE RELEASES TO WATER,DISPERSION AND DEPOSITIONA.

Recapitulation of the 2013 report

31.
The Committee had concluded that the direct discharges and releases from FDNPS tothe ocean mainly occurred during the first month following the accident, and that thecontinuing releases were unlikely to affect the Committee’s assessment of doses to the public
10

The new data reported in several of the publications cited above (e.g., better measurements of 137Cs in soils, itsparticle size distribution and its resuspension) will be useful for any future re-assessment of doses to members of
the public.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 9significantly. The Committee had judged that these direct releases were about 10–20 PBq for
131
I and 3–6 PBq for 137Cs, mainly on the basis of estimates derived using three-dimensionalmodelling. In addition, the Committee had judged that the release to the ocean due todeposition from the atmosphere was about 60–100 PBq for 131I and 5−8 PBq for 137Cs, with
only a small percentage of this occurring within a radius of 80 km from FDNPS. The
Committee had concluded that measured levels of 137Cs in seawater near the FDNPS site
declined rapidly from a peak of 68,000 Bq/L (6.8 × 107 Bq/m3) on 7 April 2011 and weregenerally below 200 Bq/L (2 × 105 Bq/m3) by the end of April, after which the rate of decrease
was much smaller. Concentrations decreased rapidly with distance from the coast: at 15 km
and 30 km offshore from the FDNPS site, they were about 100 times and 1,000 times lower,
respectively, than near the FDNPS site. The measured levels of 137Cs in sediment generally lay
between 10 and 1,000 Bq/kg of dry sediment, except in the port of FDNPS, where measured
levels were much higher.
32.
At the time the 2013 report was finalized, radioactive water had still been leaking on
the site, and groundwater had been transporting radionuclides into the aquatic environment.
The Committee had also noted the appearance of significant amounts of fission and activation
products in stagnant water in the basements of the reactor and turbine buildings. The
Committee had identified that key priorities for scientific research were to improve thecharacterization of the leaks and releases to the aquatic environment, and forecasting andquantifying the long-term transport and mixing of these releases.
B.

Findings of review of new publications

33.
The Committee concluded in the first and second white papers that its findings in thisarea of the 2013 report remained valid and were largely unaffected by new information that
had since been published. It noted several publications that would contribute to an improved
understanding of the release and subsequent dispersion of radionuclides in the marine
environment.
34.
Of the publications considered in this third white paper, seven have been reviewed indetail. None contradicted the findings of the 2013 report, and several confirmed the assumptionof a general decreasing trend in direct discharge to the ocean. Several publications addressed
identified research needs. Their contributions are summarized in the following paragraphs.
35.
Two publications derived new estimates of the releases of radiocaesium to the Pacific
Ocean. Inomata et al. [I4], using optimal interpolation of the measured concentrations of 134Cs
in seawater, estimated the inventory of this radionuclide in the North Pacific to be
15.3±2.6 PBq at the end of March 2011. About half of this inventory was to be found in the
coastal region near FDNPS. Tsubono et al. [T10] carried out an ensemble analysis ofsimulations of radionuclide dispersion to evaluate the uncertainties linked to the chaotic
behaviour of the ocean. Based on a regression between simulated and observed 134Cs
concentrations, the total 134Cs flux into the North Pacific was estimated at 16.1±1.4 PBq. The
flux of 137Cs can be inferred to be comparable, because the activity ratio of 134Cs to 137Cs in thereleases was around unity [U2]. These estimates are broadly consistent with the upper end of
the range of estimates for 137Cs release (directly to the sea plus deposition from the atmosphere)
set out in the 2013 report.
36.
During May and October each year from 2013 to 2015, Fukuda et al. [F2] analysed thedissolved 137Cs concentrations in seawater within a distance of 30 km from the coast of FDNPS.
They showed that the concentrations were one to two orders of magnitude higher than those102017 WHITE PAPER

before the accident. Concentrations were highest within 5 km of the coast (20 to 220 Bq/m3),
but these showed high variability with time. Concentrations tended to decrease with increasing
distance from the coast, reaching 2–4 Bq/m3 at 30 km. Two possible sources for the relatively
high concentrations and high temporal variability were identified: heavy rainfall increasing the
input into the ocean from rivers; and increased discharges of contaminated water to the open
sea from the FDNPS harbour facility.
37.
In September 2013, Castrillejo et al. [C1] reported on concentrations of 90Sr in seawater
samples taken off the coast of Fukushima Prefecture. The highest concentrations in surface
water were found close to FDNPS and were between 0.8 and 8.9 Bq/m3, suggesting continuing
releases of 90Sr from FDNPS. Estimates made by Castrillejo et al. indicated that the inputs
from continuing releases from FDNPS probably exceeded the inputs from rivers by two to
three orders of magnitude. Compared to measurements made in June 2011, concentrations in
September 2013 were one order of magnitude lower for 90Sr and 2−3 orders of magnitude
lower for radiocaesium. Castrillejo et al. considered this relative enrichment in 90Sr to be either
the result of inputs from groundwater or from leaks of tanks containing water from which
caesium had been removed.
38.
The transport of radiocaesium over long distances in the Pacific Ocean was monitored
during the summer of 2012 along a trans-Pacific line from the Arctic to Antarctic Oceans[K11]. Caesium-134 was only observed between 25 and 63°N (at the northern edge of theBering Sea), indicating that 134Cs released as a result of the FDNPS accident had not beentransported to the Arctic Ocean by the summer of 2012. The north–south distribution found by
Kumamoto et al. [K11] was consistent with the results of ATDM modelling of deposition of
releases to atmosphere on to the ocean. In measurements made about two years later, in 2014,
between 45 and 50°N, Inoue et al. [I6] found that 134Cs concentration had not decreased in thearea of the Oyashio current, indicating that radiocaesium was being continually transported tothis area. At the same time, Kumamoto et al. [K12] found that the elevated concentration of134
Cs observed in 2012 to the north of the Kuroshio Front (35–40°N) had disappeared,
probably because of its eastward propagation along the surface current towards the North
American coast. At the eastern edge of the Pacific basin, off the west coast of the North
American continent, southward transportation of released radiocaesium was not observed. In
the western subtropical area, the released radiocaesium had reached about 15°N by 2014
(compared to 18°N in 2012) with a maximum concentration at around 200 m depth, indicativeof a southward transport in the water mass called Subtropical Mode Water. Because of themode of formation of this water mass, Kumamoto et al. [K11] inferred that the origin of the134
Cs in this water mass was probably deposited from the atmosphere to the south of theKuroshio Current (between 30 and 35°N).
39.
Nagao et al. [N1] measured concentrations of 137Cs in the Niida River (about 25 km to
the north of FDNPS) of between 0.025 and 4.18 Bq/L between May 2011 and November 2012.
Concentrations were generally found to decrease with time, although higher values weresuperimposed on this decreasing trend during high river flows, attributed to rainfall events.
Naulier et al. [N4] analysing 137Cs in six coastal catchments showed that, during low tomoderate river discharge flows, the main carrier of radiocaesium in the deposited sediment andsuspended sediment was the particulate organic matter, whereas during extreme flooding it was
the mineral phase.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 11

C.

Potential implication of new publications

40.
The Committee has concluded that its findings in this area of the 2013 report remain
valid and are largely unaffected by new information that has since been published. The
Committee has noted several publications that will contribute to an improved understanding of
the release and subsequent dispersion of radionuclides in the marine environment.

V. UPDATES ON THE TRANSFER OF RADIONUCLIDES INTERRESTRIAL AND FRESHWATER ENVIRONMENTS
A.

Recapitulation of the 2013 report

41.
In the 2013 report, the Committee had modelled transfers through the terrestrial andfreshwater environments to estimate doses to members of the public from ingestion offoodstuffs for the second year after the FDNPS accident onwards. The Committee had
estimated these doses using the FARMLAND model [B1]. This model was used to predict the
migration of deposited radionuclides into the soil and their subsequent uptake into foodproducts. Some modifications had been made to the model to account for East-Asian
agricultural conditions (especially for rice, vegetables and fruit), but many radiological andagricultural parameter values based on Northern European data had been retained.
42.
In the 2013 report, the food categories with the highest per capita intake by weight for
adults, included in the assessment of doses from ingestion for the second year onwards, hadbeen rice, “other vegetables” (assumed to be in the leafy green vegetables category), wheat andwheat products (assumed to be in the cereals category), fruit and milk. The aim had been to
make realistic estimates of doses and the focus had been on assessing average doses torepresentative groups in the population; therefore, consumption of wild food products, such as
game animals, mushrooms, and freshwater fish, had not been considered.
43.
On the basis of these assumptions, and that food restrictions remained in place, theCommittee had estimated doses from ingestion for periods after the first year that were one totwo orders of magnitude lower than those from external exposure to deposited radionuclides.
Several subsequent studies, in which the internal exposure of people has been estimated more
directly from human measurements, have confirmed the dominance of the external exposure
pathway, and have indicated that doses from ingestion estimated using the FARMLAND
model were more likely overestimates than underestimates (see section VI below).
44.
The Committee had identified the need to better characterize the distributions of doses
to the public and to better quantify the uncertainties in the dose estimation as priorities for
future research. In this context, notwithstanding the minor contribution that ingestion offoodstuffs had made to estimated doses, better information on the transfer of radionuclides tofoodstuffs, and specifically regional and national parameters for models would be useful for
future assessments of the consequences of the FDNPS accident and to assess the impacts offood restrictions and remedial measures. In addition, such information would be helpful toimprove understanding of the potential impact of environmental remediation programmes.

122017 WHITE PAPER

B.

Findings of review of new publications

45.
The Committee had not explicitly considered new publications on transfers through theterrestrial and freshwater environments in its first white paper. In the second white paper theCommittee’s review was confined to papers published in 2015 with priority given to thetransfer pathways of radiocaesium (which had made the dominant contribution to ingestion
doses after the first year) to food products. The Committee concluded from its review that its
assumptions and findings in this area of the 2013 report remained broadly valid. For this third
white paper, the Committee has reviewed similar information published in 2016 as well as
considering some other relevant papers published after the accident that it had not previously
considered.
46.
Of the publications considered in this third white paper, 32 have been reviewed in detail.
The main implications of the findings of these publications are summarized below.
1.

Radiocaesium migration in soil

47.
In the 2013 report, migration of radiocaesium into deeper layers of well-mixed soil used
for crop production had been assumed to be slow, with, for example, only about 7% migrating
below the top 30 cm of well-mixed soils after 10 years. No data have yet been identified for
agricultural soils that show radiocaesium attributable to the FDNPS accident at soil depths
below 30 cm.
48.
The partition coefficient (Kd) provides an indication of the bioavailability of aradionuclide in soil; a high Kd denotes strong sorption and, therefore, low bioavailability.
Konoplev et al. [K9] reported that measured values of the Kd for radiocaesium between
suspended soil particles and water published in five papers since the FDNPS accident varied
between 1.1 × 105 and 11 × 105 L/kg; these values were one to two orders of magnitude higher(indicating much lower bioavailability) than values found in areas affected by the Chernobyl
accident in the first few years after it occurred. The difference was attributed to (a) the higher
proportion of clays in the prevailing soils and sediments in areas affected by releases fromFDNPS and (b) the presence of radiocaesium associated with glass particles, which have beenreported in areas affected by the FDNPS accident.
49.
Mishra et al. [M6] measured lower Kd values (varying from around 80 to 320 L/kg for
10 cm depth soil samples) in three undisturbed grassland sandy soils (which would be expected
to bind radiocaesium to a lesser extent than soils with higher clay contents) in other areas ofJapan. The vertical migration of radiocaesium was found to be slow with more than 90% of theradiocaesium retained within the upper 5 cm layer.
50.
Konoplev et al. [K9, K10] focused on Okuma town soils within 10 km of FDNPS andparts of the Niida river, and reported that, in both of these areas, small amounts of 134Cs and137
Cs were detected in some of the soils at soil depths of more than 20 cm. The verticalmigration of radiocaesium in undisturbed forest and grassland soils near the FDNPS site was
faster than that in soils within the 30 km zone of the Chernobyl nuclear power plant for asimilar time interval. Possible reasons for both these differences include higher precipitation,
more bioturbation and higher soil temperatures. In undisturbed soils, faster vertical migrationof radiocaesium has been reported in forest soil compared to grassland soil [K10].
51.
Uematsu et al. [U1] found that Japanese soils appeared to have a lower affinity forbinding radiocaesium than temperate European soils with similar soil clay and exchangeable

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 13

potassium contents, possibly owing to differences in mineralogy. They considered that soil
characteristics generally used in existing mechanistic models were not a good basis forpredicting the transfer of radiocaesium from soil to grass. Further soil characteristics need to beincorporated into models to be suitable for Japanese soils.
52.
Mukai et al. [M11, M12] have identified partially vermiculated (or weathered) biotite,
as found in soils in Fukushima Prefecture, to be a more effective binder for radiocaesium thanother micaceous minerals or organic matter.
53.
Kitamura et al. [K7] developed three-dimensional models of the river basins of fivecatchments in Fukushima Prefecture to estimate water flow rates, suspended sedimentconcentrations and accumulated sediment erosion and deposition. They found that the majorityof annual sediment migration in the basins occurred over storm periods, so typhoons were themain vectors for redistribution. Evrard et al. [E4] showed that, between 2012 and 2015, there
had been a decrease of around 90% in the contribution of radiocaesium in upstream soils toradiocaesium concentrations in sediment transiting the coastal plains. The occurrence of
typhoons and decontamination efforts in various tributaries of the Niida River have resulted insome temporary increases in local radiocaesium concentrations. However, the much lower
contribution of radiocaesium from upstream soils to coastal plain sediment in November 2015
indicates that the source of the easily erodible radiocaesium may have been removed bydecontamination, diluted by subsoils, or eroded and transported to the Pacific Ocean.
2.

Radiocaesium transfer from soil to crops

54.
Values of the concentration ratio (CR 11 – the ratio of the concentration of aradionuclide in the food product to its concentration in soil to 20 cm depth on a dry weightbasis) for the transfer of radiocaesium from soil to brown rice, or data that can be used toderive the CR, have been reported by Yang et al. [Y5], Endo et al. [E3], Wakabayashi et al.
[W3], Ohmori et al. [O7], Tsukada and Ohse [T11], and Eguchi et al. [E2]. Most data in thesepublications for rice sampled from 2011 to 2014 suggest that the CR for brown rice may havebeen higher (by up to around one order of magnitude) than that assumed in the 2013 report.
The changes of 137Cs concentration in rice over time between 2012 and 2014 were similar to
those predicted by the FARMLAND model [W3, Y5].
55.
Kusaba et al. [K14] confirmed earlier data showing that, in the first three years after
deposition, radiocaesium adhered to bark surfaces was a more important source ofradiocaesium in fruit than radiocaesium in soil. From 2011 to 2014 the 137Cs concentration inapples declined at a faster rate than would be predicted by the FARMLAND model. The CR
for apples in the period 2012–2014 was similar to that predicted by the model.
56.
In 2012, Win et al. [W6] measured 137Cs uptake in 97 cultivars of the azuki bean, whichis the second most important legume consumed in Japan and is an important crop in Fukushima
Prefecture. Tenfold differences in CR were noted between cultivars, and the CR values—
allowing for reductions with time and soil depth corrections—were mostly lower than thatassumed in the FARMLAND model.
11

The transfer of radiocaesium from soil to crops is normally quantified using the concentration ratio (CR), often
denoted Fʋ, and also sometimes called the transfer factor (TF). Some authors used the term TF and/or slightly
different soil depths so, where relevant, the impact of the different depth has been taken into account in thereviewed CR values.

142017 WHITE PAPER

57.
Djedidi et al. [D1] measured the CR for a large number of Brassica cultivars in fieldtrials conducted in 2013. For field mustard, Indian mustard and oilseed rape, the CR values for137
Cs were relatively high and most of them exceeded the assumed value for leafy green
vegetables in the FARMLAND model. From May 2011 to May 2013 the reduction in the 137Csconcentration in tea leaves was greater than that predicted by the FARMLAND model for leafy
green vegetables [H5].
58.
Sunaga and Harada [S13] developed a magnetic analyser method for estimating soil
adhesion on plants and applied it to some rye crops. They found that the radiocaesium
concentration was linearly correlated with the amount of adhered soil and that plants with ahigher yield had relatively less adhered soil. The adhered soil accounted for about half of thetotal radiocaesium concentration of Italian rye grass, which—with lower yields and plant
lengths—had a high soil loading. The highest values measured for both forage and Italian rye
grass were one order of magnitude smaller than that assumed by the FARMLAND model forhay/silage or for pasture.
59.
For agricultural animals, a study conducted early in spring 2011 showed that milk ofhoused dairy cows had much lower concentrations of 131I, 134Cs and 137Cs compared with thosethat were outdoors on pasture [K8]. Manabe et al. [M4] noted that most farm animals are kept
in closed barns in Japan. This is confirmed by information readily available at the website of
the Ministry of Agriculture, Forestry and Fisheries of Japan. For example, of the 14,800 dairy
cattle in Fukushima Prefecture after the accident only 720 grazed outdoors [M1, M2]. The
transfer coefficients for radiocaesium measured in four studies in controlled conditions withhoused cows [H2, K8, O8, O9] were similar to those assumed in the FARMLAND model. A
transfer coefficient measured for pigs fed rice [O6] was the same as that assumed in the
FARMLAND model.
3.

Radiocaesium transfer to food products not considered in the 2013 report

60.
Fuma et al. [F4] considered monitoring data from 2011 to 2015 and reported that theannual mean radiocaesium concentrations in bamboo shoots gradually decreased with time, but
the rate of reduction was slower than that for agricultural produce.
61.
Wada et al. [W2] summarized compiled data for sixteen species of freshwater fish froman extensive monitoring programme conducted by Fukushima Prefecture. A higher proportionof freshwater fish than marine fish had radiocaesium concentrations that exceeded the level atwhich food restrictions applied, especially in the first two years after the accident [W2]. In
2014, food restriction levels were only exceeded in areas with the highest deposition densities,
and maximum radiocaesium concentrations did not exceed 750 Bq/kg wet weight.
62.
Cultured fish are more commonly eaten in Japan than “wild” fish collected from lakes
and rivers. Cultured fish had considerably lower radiocaesium concentrations than wild fish
[Y3] partially because radiocaesium transfer to freshwater fish is mainly via the food chain
whereas cultured fish are fed with commercial pellets [W2]. A correlation was reported
between radiocaesium deposition density and radiocaesium concentrations in various
freshwater fish species [A5], especially along the higher deposition area to the north-west of
FDNPS. Radiocaesium concentrations in lake fish were generally higher than in those fromrivers [W2]. There has been a considerable reduction with time since 2011 in the radiocaesium
concentrations in wild fish species [A5, I3, W2].

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 15

63.
Wada et al. [W2] found that the radiocaesium concentrations in different freshwater
fish species and changes with time were specific to area and habitat. They were affected byfish-feeding strategies, life cycles, and features of water bodies such as the lower turnover timein lakes than rivers. For example, there was a trophic level effect such that radiocaesium
concentrations generally declined in the order: carnivorous (e.g. salmonids) > omnivorous >herbivorous > planktivorous species [A5, I3, W2]. A relatively high concentration ratio (fish towater) for Ayu (a salmonid) was reported in 2011, and the intake of algae with associatedsediment was identified as the most important pathway for 137Cs transfer into Ayu [I3]. The
retention time of 137Cs inside Ayu was relatively short, whereas for other salmonids it wasmuch longer [W2].
64.
Tagami et al. [T1] reported high transfer of radiocaesium to a range of wild animal
species (particularly bears, wild boar, sika deer and the copper pheasant) in five prefectures
between 2011 and 2015, and long effective half-lives. Similarly, high transfers to hunted
animals occurred in Europe after the Chernobyl accident.
C.

Potential implication of new publications

65.
The Committee has concluded that its assumptions and findings in this area of the 2013
report remain broadly valid. New information specific to Japanese conditions has become
available on transfers of radioactive material in soils and into foods. This information would be
more appropriate for any future assessment of the FDNPS accident than parameter values
based on European conditions (which had been used in the 2013 report in the absence of more
relevant alternatives). Use of this information may lead to changes in the time-dependence ofthe doses from ingestion of foods predicted for the second year after the accident onwards andin the relative importance of different foodstuffs. For example, the contribution of animal
products to doses from ingestion of foods over the longer term is likely to have been
overestimated, because of the conservative assumption that some agricultural animals graze on
pasture whereas most farm animals in Japan are housed. However, the Committee expects thatthe overall effect on predicted doses due to ingestion for the second year onwards would beminor, mainly because of the continued application of food restrictions. In addition,measurements on people (see chapter VI below) have confirmed that internal exposure wasvery small compared with external exposure, and suggested that the doses from ingestion offoods as predicted in the 2013 report for the second year onwards were likely to have been
overestimates.
66.
The following areas of research would be particularly beneficial in providing better
regional and national parameters on the transfer of radionuclides to foodstuffs for futureassessments and in improving understanding of the potential impact of environmental
remediation programmes:(a) Continued study of the migration of radiocaesium in agricultural, freshwater andforest environments and their transfer into various agricultural, aquatic and wild foods(especially in the categories of rice and “other vegetables”, freshwater fish, hunted animals,
wild plants and mushrooms);(b) Further development of spatial and temporal models of environmental transfer
processes specific to the diversity of food produced and consumed in Japan to support theprediction of long-term ingestion doses, addressing, in particular: feeding and management
regimes of key domestic agricultural animals and wild animals; and the potential long-term
contribution of transfer of radiocaesium in rivers and lakes to food products;

162017 WHITE PAPER(c) Continued monitoring of long-term changes with time in radiocaesium concentrations
in various agricultural and wild foods;(d) Continued study of the effectiveness of remediation measures in reducing
radiocaesium transfer from soil to agricultural products.

VI. UPDATES ON EVALUATION OF DOSES FOR THE PUBLIC
A.

Recapitulation of the 2013 report

67.
The Committee’s aim had been to make realistic estimates of doses to defined groups ofindividuals considered representative of the different subsets of the Japanese population. For
the assessment of doses from external exposure, the Committee had used models withparameter values mostly derived from European studies after the Chernobyl accident, andvalidated with numerous individual measurements by thermoluminescent dosimeter conductedin the affected Bryansk region of Russia. The Committee had used these models in its 2013
report in combination with population-averaged deposition densities of radionuclides forJapanese districts or prefectures, derived by combining measurements of radionuclide
deposition densities with the density of population. Data on population densities as well as onage compositions and occupancy factors for different groups of the Japanese population had
been based on the 2010 Japanese census.
68.
For the assessment of doses to the public from internal exposure, the Committee had
considered two exposure pathways, inhalation and ingestion. Exposure from inhalation had
been assessed only from radionuclides in the passing radioactive plume, with subsequent
inhalation of resuspended radionuclides considered insignificant. Exposure from inhalation ofradionuclides in the passing plume had been estimated from measurements of deposition
density using ratios of the concentrations of radionuclides in air to deposition density levels
derived using the assumed source term and ATDM.
69.
Intakes of radionuclides in food and drinking water in the first year following theaccident had been assessed using the database of food and drinking water measurements
carried out in Fukushima Prefecture and other prefectures of Japan. This database included
many measurements made for food inspection purposes and therefore had some bias associatedwith the sampling: samples with potentially elevated concentrations were more likely to havebeen selected. However, at the time of preparation of the 2013 report, no other foodmeasurements had been available.
70.
For subsequent years, a modified form of the FARMLAND model [B1] had been
applied for estimating the transfer of radionuclides through terrestrial food chains, with sometransfer coefficients adjusted for the conditions and agricultural practices of contemporary
Japan. The model had been used in combination with input data on population-averaged
deposition densities of radionuclides for Japanese districts or prefectures.
71.
For residents of evacuated communities, where it had not been possible to use
measurements of radionuclide concentrations in the environment, the Committee had estimatedtime-varying concentrations of radionuclides in the environment using the assumed source
term for releases to the atmosphere and ATDM. Doses from external exposure and frominhalation had then been estimated for the periods before, during and after evacuation using

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 17

scenarios representing the movements of residents derived from the results of a survey using
questionnaires.
72.
Measurements of radionuclides in people, such as whole-body and thyroid
measurements, provide a direct source of information on internal exposure. However, at thetime of preparation of the 2013 report, the number of thyroid measurements had been limited(about 1,100 persons) and these data could only be used to corroborate modelled doses to thethyroid in a few settlements. In addition, data from whole-body measurements had become
available to the Committee at a late stage of the 2013 report preparation, and comprehensive
data analysis had not been possible. Nevertheless, some assessment of doses from internal
exposure based on human measurements had been carried out by the Committee and were
presented in the 2013 report (see paragraphs 116–118 of [U2]). These had indicated that
estimates of doses from internal exposure based on whole-body measurements were
substantially lower than those based on modelling.
B.

Findings of review of new publications

73.
In the first and second white papers, the Committee concluded that its findings in thisarea remained valid and were largely unaffected by new information that had been publishedsubsequently. By far the majority of the new publications broadly supported or confirmed themain assumptions made in, and the findings of, the 2013 report. Further whole-bodymeasurements had given added weight to the statement made in the 2013 report that effective
doses from ingestion of radionuclides in foodstuffs may, in practice, have been much lower
than those estimated theoretically.
74.
Of the publications considered in this third white paper, 11 were reviewed in detail. The
main implications of the outcome of this review are summarized below.
1.

External exposure

75.
Realistic assessments of current and future individual doses from external exposure areneeded as an input into decisions to lift the evacuation order in affected areas in Fukushima
Prefecture and allow people to return. Naito et al. [N3] used personal electronic dosimeters(D-Shuttle) along with the Global Positioning System and Geographic Information System torelate individual doses from external exposure to ambient doses, and activity-patterns ofindividuals. The dosimeters of the 142 participants provided 29,550 hourly exposure data
points that were used for analysis. The results showed that the additional (i.e. relative tobackground) individual doses from external exposure were well correlated with the additional(relative to background) ambient dose determined from an airborne monitoring survey. From
the results of linear regression analysis, Naito et al. [N3] suggested that the additional
individual doses from external exposure were numerically on average about one fifth that of
the additional ambient doses. The reduction factors (the ratios of the additional individual
doses to the additional ambient doses) were calculated to be on average 0.14 and 0.32 for timespent at home and outdoors, respectively, which is in good agreement with the model used in
the 2013 report [U2]. The contribution to the total individual dose due to external exposure
from that received during each type of activity (i.e. at home, in other buildings, outdoors, intransport, and other) was in good agreement with the fraction of time spent daily in each typeof activity. The results contributed to an improved understanding of how realistic estimates ofindividual dose from external exposure can be derived from measurements of ambient doses
from airborne monitoring and information about the time individuals spend on different

182017 WHITE PAPER

activities. The data will be useful in any assessment of future cumulative doses after the returnof residents to evacuation order areas in Fukushima Prefecture.
76.
Sakumi et al. [S3] measured individual doses to workers from external exposure in theevacuated village of Iitate during an 11-month period in 2013 (see chapter VII below). Fromthe maximum dose measured for these workers, the authors estimated the annual dose fromexternal exposure for a hypothetical resident who returned to Iitate village in 2013 to be about
10 mSv, but this was based on the unrealistic assumption that the individual stayed outdoors
24 hours a day during the year. A more realistic estimate based on the model used in the 2013
report for an outdoor worker would be about 5 mSv in 2013 and 3 mSv in 2015 [I1, U2].
77.
Malins et al. [M3] developed a tool that calculates ambient dose equivalent rates at 1 m
above the ground based on a model that accounts for 134Cs and 137Cs soil deposition density,
depth profile and horizontal distribution within the ground. Good correlation was foundbetween predicted dose rates and dose rates measured with survey meters in Fukushima
Prefecture in areas with radiocaesium deposition from the FDNPS accident. Reductions seen indose rates in air above flat, undisturbed fields in Fukushima Prefecture were consistent withradioactive decay and downward migration of caesium into soil; the predictions of the tool
were in good agreement both with the measurements and with the model used in the 2013
report [U2]. The tool could also be useful in making realistic estimates of future doses fromexternal exposure.
78.
Ishikawa et al. [I8] assessed time spent outdoors (an important factor in estimating
doses from external exposure) for residents of Iitate village from information collected in the
Basic Survey conducted by Fukushima Medical University in Fukushima Prefecture [I7]. From
3,400 responses to the questionnaire collected from residents in Iitate village, the authors
randomly selected a total of 240 responses in accordance with the distribution of the original
population by age groups, and estimated the average time spent outdoors per day. The
arithmetic mean for the 170 individuals for whom there was a full set of data on behaviour for
four months was 2.08 (95% CI: 1.64, 2.51) hours. This is a much smaller value than commonly
assumed in many dose assessments, although a value of 2.4 hours had been adopted for indoor
workers in the 2013 report [U2].
2.

Internal exposure(a)Assessment of early intakes and doses

79.
Three substantial papers [K5, K6, T5] have been published addressing the difficult
issue of estimating thyroid doses from internal exposure resulting from intake of short-lived
radionuclides (mainly 131I) in the absence of early environmental and human measurements.
80.
Kim et al. [K6] presented an assessment of the doses from internal exposure to
174 residents living near FDNPS at the time of the accident based on whole-bodymeasurements performed by the National Institute of Radiological Sciences (NIRS) during theperiod between 27 June and 28 July 2011. The 174 subjects consisted of 125 adults and
49 children and included 90 individuals from Namie town, a municipality within the 20 km
evacuation zone. The number of subjects in whom both 134Cs and 137Cs were detected was
relatively small: 28.8% for the adults and 4.1% for the children. A significant gender differencein the radiocaesium concentrations in the whole body (males > females) was observed for
adults but not for children. The committed effective dose (CED) from 134Cs and 137Cs wasDEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 19

calculated by correcting individual whole-body measurements for body size, and assuming
intake was by acute inhalation of compounds easily soluble in the lungs on 12 March 2011,
when the first explosion occurred at FDNPS. The resulting 90th-percentile of the CED
distribution for adults was around 0.1 mSv and the maximum CED (0.63 mSv) was found for
an elderly male. Comparable CED results were obtained from other whole-body measurements
subsequently performed by the Japan Atomic Energy Agency (JAEA) in a similar manner tothat of NIRS. Based on measurements of 131I in the thyroid made by Tokonami et al. [T9] on adifferent group of adult subjects from the same and neighbouring municipalities, Kim et al.
evaluated an intake ratio of 131I to 134Cs of around three to five. Kim et al. then used theaverage intake ratio of 3.8 to estimate the median and maximum equivalent doses to thethyroids of adult subjects of their study as 3.5 mSv and 84 mSv, respectively. For comparison,in the 2013 report, the settlement-average absorbed dose to the thyroid in the first year after theaccident for adults evacuated from Namie town was estimated to be 34 mGy [U2]. There aresome reservations associated with this approach, particularly the use of intake ratios of 131I to
134
Cs derived from whole-body and thyroid measurements made by different research groups
with different study subjects, and the authors did not assess the uncertainty associated with theuse of the average value derived. The ratio of the concentrations of 131I to 134Cs measured insoil was very different in some locations (e.g. to the south of FDNPS) than in others [U2], andintake scenarios may not be the same for different age groups. The authors acknowledged theuncertainties associated with their approach and plan further studies on the relationshipbetween individual doses from internal exposure and personal behaviour after the accident.
81.
Kim et al. [K5] reported on other estimates made by NIRS of the dose to the thyroid
due to internal exposure for residents of Fukushima Prefecture. This estimation was performed
using a combination of information from direct thyroid measurements of 1,080 children (131I)
made at the end of March 2011, about 3,000 whole-body measurements of adults (134Cs, 137Cs)
made between 11 July 2011 and 31 January 2012, and ATDM simulations of 131I
concentrations in air for areas where no direct measurements were available. By comparing
estimated doses to the thyroid of children due to 131I with CEDs to adults due to 134Cs and 137Cs
for those locations (Iitate village and Kawamata town) where estimates of both were available
from direct measurements, an intake ratio of 131I to 137Cs of three was derived. The ratio wasthen applied to the whole-body measurement information for other municipalities to estimate
thyroid doses for these municipalities. The highest doses to the thyroid from internal exposure
were estimated for residents of Futaba town, Iitate village and Iwaki City and were mostly
below 30 mSv. The authors compared their estimates with the somewhat higher values in the2013 report but noted that the latter included doses from ingestion, whereas the authors’
method did not. The likely overestimation of doses to the thyroid (owing to the assumed intake
by ingestion) was acknowledged in the 2013 report and confirmed by analyses undertaken by
IAEA [I1] that showed that inhalation was by far the largest contributor to exposure of the
thyroid. The 2013 report estimates also took account of even shorter-lived radionuclides (132I,
132
Te and 133I), as well as 131I. This study is associated with similar reservations to the study
described in the previous paragraph. To address remaining issues, including the dose
contribution from ingestion, the authors proposed a new dose estimation method using data on
personal behaviour and presented examples of the preliminary analyses.
82.
Tani et al. [T5] calculated 131I concentrations in breast milk of nursing mothers in
Ibaraki Prefecture, based on a biokinetic model for iodine and scenarios for time-varying
intakes due to inhalation of ambient air and to ingestion of tap water, and using relevantmeasurements of 131I concentrations in air and in tap water. The authors compared thecalculated 131I concentrations in breast milk with those measured in a small number of samples
obtained from volunteers living in Fukushima Prefecture and neighbouring prefectures shortly

202017 WHITE PAPER

after the accident in 2011 and found general agreement. Tani et al. then estimated equivalentdoses to the thyroids of breast-fed infants (assuming that the infants consumed 800 mL ofbreast milk every day) of 10–11 mSv for Mito City and Kasama City and 1.1–1.8 mSv for
Tsukuba City and Moriya City. Tani et al. suggested that breast milk consumption could
therefore be a major contributor to thyroid equivalent dose from internal exposure for breastfed infants in areas where concentrations of 131I in air were relatively low; however, the authors
pointed out that further studies including personal behaviour surveys would be necessary toestimate individual doses.
(b)

Assessment of current exposures

83.
Orita et al. [O11] evaluated the current concentrations of radiocaesium in local foods
collected in Kawauchi village, which is located less than 30 km from FDNPS, in order toassess doses to the public from ingestion and to minimize public anxiety regarding internal
exposure after the accident. The number of samples exceeding the regulatory limit forradiocaesium (100 Bq/kg for general foods) was 5 out of 4,080 samples for vegetables (0.1%),
652 out of 1,986 samples for edible wild plants and fungi (32.8%), and 8 out of 647 samples
for fruits (1.2%). The study confirmed that the annual effective doses from internal exposure asa result of ingesting these foods were low, ranging from 22 to 43 μSv for adults. The authors
considered that comprehensive long-term follow-up studies should take place to clarify trends
in radiocaesium concentrations in local foods and CEDs in Fukushima-area residents.
84.
Aono et al. [A4] studied the dynamics of radionuclide concentrations in some
agricultural products of Japan and in seafoods collected off Fukushima Prefecture after theaccident. The concentration of 134Cs plus 137Cs in spinach produced across the whole of Japan
rapidly declined from a range of between 10 and 10,000 Bq/kg in spring 2011 to between 1 and
100 Bq/kg in 2012 and between 1 and 10 Bq/kg in 2013–2014. In contrast, the concentration of134
Cs plus 137Cs in mushrooms produced or collected from all over Japan showed little
reduction in the first three years after the accident, remaining in the range of 3 to 300 Bq/kg in
2013–2014. Many concentrations of radionuclides measured in mushrooms continued to
exceed regulatory levels established in April 2012. The concentration of 134Cs plus 137Cs incommon skate collected around FDNPS between 2013 and 2015 was measurable but mostly
below regulatory levels. Concentrations of radiocaesium in agricultural foods and marine fish
were generally found to be below the Japanese regulatory levels, but radiocaesium
concentrations above this level continued to be found in edible wild plants, wild mushrooms
and game such as boar meat. The authors considered that long-term kinetic studies ofradionuclides in terrestrial and marine environments were important both for the assessment ofdoses to the public from ingestion and for the prevention of unacceptable intakes ofradionuclides via the food chain.
3.

Remediation

85.
As the Committee noted in the first and second white papers, decontamination of
settlements in the evacuated Special Decontamination Area and inhabited Intensive
Contaminated Survey Area has been in progress since 2012. However, it continues to be thecase that dose-rate measurements made before and after remediation have not yet been
published in peer-reviewed literature. The Committee continues to note the importance ofassessing decontamination effectiveness in terms not only of dose rate reduction but also of the
reduction in the annual effective dose from external exposure of residents, both individuallyand collectively.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 21

86.
Howard et al. [H11] compared a range of different features relevant to remediation
following the Chernobyl and FDNPS accidents, including the characteristics of the distributionof radionuclides and the landscapes affected, the radiological criteria applied, the designationof areas to be remediated and the remediation measures adopted. For both accidents, the longterm goal of remediation has been an additional annual individual effective dose of less than
1 mSv, although there were differences in when this goal was applied. The scale of remediation
activities has been comparable in the two cases, even though the radiological consequences of
the FDNPS accident for the public were much lower. Some key reasons for this are that:(a) The radiological criteria for remediation applied in Japan have been lower than those
applied in the former USSR, and have therefore had relatively higher associated costs;(b)

Lower limits have been adopted for radionuclide concentrations in food in Japan;(c)

A decision was made to remediate the evacuated land in Japan.

87.
After the Chernobyl accident, the balancing of averted collective dose against
remediation costs was an important part of the remediation strategy. In Japan, remediation ofaffected districts has been justified and implemented based on radiological and/or social andcultural considerations.
88.
The tool developed by Malins et al. [M3] for the calculation of ambient dose equivalent
rate at 1 metre above the ground (see paragraph 77 above) could be useful for remediation
planning. Simulations of three remediation methods to reduce dose rates in air for farmland soil
using this tool demonstrated that topsoil removal and layer interchange strategies had similarlevels of effectiveness, and both methods were more effective than reverse tillage.
C.

Potential implication of new publications

89.
The Committee has concluded that its findings in this area of the 2013 report remain
valid and are largely unaffected by new information that has since become available. The
majority of the new publications broadly support or confirm the main assumptions made in—and the findings of—the 2013 report, in particular:(a) Doses to the general public in Japan continue to decline in line with the findings ofthe 2013 report;(b) Doses to the general public in Japan from external exposure, determined by personaldose measurements or dose-rate measurements combined with national shielding factors forbuildings and exposure scenarios, are in general agreement with the findings of the 2013
report. Papers published in 2016 further clarified external exposure patterns and determined
appropriate values for parameters in relevant models;(c) There were no publications in 2016 on large-scale measurements of current wholebody contents of 134Cs and 137Cs of residents of affected areas, but the Committee has
previously noted that the dose from internal exposure of residents of Fukushima Prefectureand neighbouring prefectures from current ingestion of caesium radionuclides with food is
generally low [U4, U5]. Concentrations of radiocaesium in agricultural foods have declined
rapidly since 2011, whereas concentrations in edible wild plants, wild mushrooms andgame such as boar meat have decreased more slowly;

222017 WHITE PAPER(d) Progress has been made in retrospective assessment of doses from internal exposuredue to early intake of radionuclides, especially of 131I for children.
90.
The Committee has identified the following areas as having the greatest potential tocontribute to addressing the research needs identified in the 2013 report:(a) Continue to measure the dose rates due to external exposure to deposited material invarious environments, forecast and track changes over time;(b) Determine parameter values necessary for national and regional models of doses (e.g.
shielding parameters of buildings; time spent outdoors and indoors in various building
types in different seasons, and as a function of age and social group; and parameters related
to the system of food production and distribution, and consumption habits of cultivated andwild foods);(c) Measure individual doses from external exposure of residents of towns with elevateddeposition of radionuclides in order to validate dosimetric models and obtain anexperimental basis for uncertainty analysis;(d)Continue efforts on thyroid dose reconstruction for 2011;(e) Further conduct in vivo measurements of caesium radionuclides in people withdifferent food habits to support refinement in the estimation of current doses from internal
exposure and their uncertainties;(f) Measure concentrations of caesium radionuclides in various agricultural and wild
foods as a function of time after the FDNPS accident;(g) Quantify the impact of environmental remediation programmes (decontamination,
agricultural measures and others) both in terms of reduction of environmental radiation
indicators (dose rate, radionuclide concentrations, and so on) and averted dose to residents
from external and internal exposure;(h) Better characterize the distributions of modelled doses to the public, expressing
variability between individuals using probabilistic approaches, and compare them withhuman measurements.

VII. UPDATES ON EVALUATION OF DOSES FOR WORKERS
A.

Recapitulation of the 2013 report

91.
The main aim of the Committee’s work had been to judge the extent to which theindividual doses reported in Japan provided a true and reliable measure of the doses actually
incurred by workers, and therefore the extent to which the reported doses could support a
reliable commentary on the implications for health. By the end of October 2012, the Tokyo
Electric Power Company (TEPCO) had reported statistics on doses to about 25,000 workers at
the FDNPS site, most of whom were employed by contractors. According to TEPCO’s reports,
the average effective dose to FDNPS workers over the first 19 months after the accident had
been about 10 mSv. About 34% of the workforce had received effective doses over this period
above 10 mSv, while 0.7% of the workforce (corresponding to 173 individuals) had received
effective doses more than 100 mSv. The highest reported effective dose was 679 mSv for the
TEPCO worker who had also received the highest reported CED due to internal exposureDEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 23(590 mSv). Dose statistics had been reported separately for a few hundred emergency services
workers.
92.
The Committee’s independent assessments of the doses due to internal exposure for
12 workers (out of a total of 13) who had CEDs due to internal exposure higher than 100 mSv
had confirmed that they had received absorbed doses to the thyroid due to inhalation of 131I in
the range of 2 to 12 Gy.
93.
The reliability of the internal exposure assessments for the much larger number ofworkers with lower assessed internal exposures had been evaluated by performing independent
assessments for randomly selected samples of workers.
94.
The Committee had confirmed the reliability of assessments reported by TEPCO for
those of its workers where 131I in the body had been detected. However, for most of theworkers, in vivo monitoring of 131I in the thyroid had not started until the second half of May
2011, and in many cases this delay had meant that 131I could no longer be detected. For thesame reason, the contribution to internal exposure from intakes of shorter-lived radionuclides
such as 132Te and 133I could not be reliably assessed. The Committee had been unable toconfirm the reliability of the assessments reported by TEPCO for those of its workers forwhom 131I had not been detected in the body, nor the reliability of the internal exposure
assessments reported by contractors for their workers.
95.
The Committee had judged that the major factor potentially affecting the reliability of
external exposure assessments had been the sharing of electronic personal dosimeters during
March 2011 (because the majority of the dosimeters had been lost in the tsunami flood), with
only one worker in a team wearing a dosimeter for many missions.
96.
The Committee had had insufficient information on beta irradiation to make an
informed assessment of doses to the eye lens of workers (paragraph 143 in [U2]).
B.

Findings of review of new publications

97.
The Committee concluded in the first and second white papers that its findings in thisarea of the 2013 report remained valid and were largely unaffected by new information that had
been published. While significant changes had been made to doses estimated for some workers
since the 2013 report (see [U4] and [U5]), the Committee did not expect that these would
materially affect its main findings, although this would need to be confirmed by a fuller analysis.
98.
Of the publications considered in this third white paper, three have been reviewed indetail. One publication by Yasui [Y7] presented recommendations for the design of a largescale epidemiological study on workers, developed in a meeting of experts convened by theJapanese Ministry of Health, Labour and Welfare (MHLW); when published, results of thestudy would almost certainly be relevant for any follow-up assessment to the Committee’s
2013 report. A second publication [Y6] reported on the establishment of a dose registration
system for decontamination workers and presented dose statistics for the period April 2011 to
December 2014. A third publication [S3] reported results of individual measurements ofeffective dose due to external exposure for workers in the village of Iitate during 2013; data forworkers and dose predictions for returning evacuees derived from the worker data could be
useful in any follow-up assessment.

242017 WHITE PAPER

99.
The worker epidemiological study described by Yasui [Y7] aims to examine adverse
health effects in a target group of approximately 20,000 FDNPS emergency workers. No
results from the study have yet been published, but a pilot study has been completed, and thefull-scale study commenced in April 2015. The study will continue for the lifetime of theworkers in the target group. A comprehensive re-evaluation of doses from external exposure
and internal exposure was proposed at the meeting of experts, as was an analysis of thereliability and validity of assessed doses. The experts also recommended biological dosimetry(specifically, chromosomal tests using the fluorescence in situ hybridization method) for
workers whose effective doses exceeded 100 mSv. Although the study is comprehensive in its
coverage, and its design is thorough, the Committee considers that two aspects of the study
design relating to dosimetry warrant further consideration:(a) The study recommends the estimation of cumulative effective dose up to the point ofhealth examination as the measure of exposure. The Committee believes it would be more
appropriate to identify the health effects to be investigated, and then identify theappropriate measure of exposure for that health effect. The measure of exposure inradiation epidemiology studies is usually the set of absorbed doses to specified organs
received in each year of exposure, rather than CED, and the organs specified (e.g. thyroid)
are selected on the basis of a consideration of the health effects to be investigated (e.g.
thyroid cancer);(b) For many workers, the delay in commencing thyroid monitoring meant that thyroid
doses from intakes of 131I could not be reliably assessed. These doses will be re-evaluatedin the study but large uncertainties in their values are likely to remain. An assessment of
the implications of these uncertainties for the expected outcomes of the study would better
inform judgements on the adequacy of its design.
100. The proposed comprehensive re-evaluation of worker doses means that the study
should be able to address several of the research needs for worker dosimetry identified in the2013 report.
101. Yasui [Y6] also reported on the establishment in December 2013 of a central dose
registration system for workers engaged in decontamination projects in special
decontamination areas. From the doses registered, Yasui presented distributions of effective
doses for each 3-month period between April 2011 and December 2014 and distributions ofeffective doses by sex and by age for each of the years 2012, 2013 and 2014. The number ofdecontamination workers progressively increased from 11,058 in 2012 to 34,611 in 2014, andthe average effective dose for these workers increased from 0.5 mSv in 2012 and 2013 to
0.7 mSv in 2014. The maximum effective doses were 13.9 mSv, 6.7 mSv, and 10.4 mSv in2012, 2013 and 2014, respectively. The results presented confirm that doses todecontamination workers were low.
102. Sakumi et al. [S3] reported results of individual measurements of effective dose fromexternal exposure for 64 workers in the village of Iitate made during an 11-month period in
2013. Although Iitate is within the deliberate evacuation area, the Japanese Ministry ofEnvironment permitted some companies to continue working there. Sakumi et al. reported thatthe workers were present in Iitate for 10 hours per day and 5 days per week. Measurements
were made with photoluminescence glass dosimeters. Sakumi et al. reported that 70% of theworkers received an annual effective dose of less than 2 mSv, and that all of the workers withan annual effective radiation dose of more than 3 mSv worked outdoors for almost 10 hours ineach working day. The maximum effective dose was 3.6 mSv for a worker working outdoors
close to a road in the centre of Iitate. The mean and median doses were 1.73 and 1.53 mSv,

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 25

respectively. The paper addresses an identified research need, although for a time period later
than that covered by the 2013 report.
C.

Potential implication of new publications

103. The Committee has concluded that its findings in this area of the 2013 report remain
valid and are largely unaffected by new information that has been published so far.
104. The proposed comprehensive re-evaluation of doses discussed by Yasui [Y7] should be
able to address several of the research needs for worker dosimetry identified in the 2013 report.
No new information was identified that would enable the Committee to reach informed
judgments on the exposure of the lens of the eye, and further research in this area would beparticularly valuable.

VIII.

A.

UPDATES ON HEALTH IMPLICATIONS FOR WORKERS AND
PUBLIC
Recapitulation of the 2013 report105. The Committee had expected health risks resulting from the FDNPS accident to be far
lower than those for the Chernobyl accident, owing to the substantially lower doses received by
the public and workers. No deterministic effects from radiation exposure had been observed
among the public and none had been expected. No increase in spontaneous abortions,miscarriages, perinatal mortality, birth defects or cognitive impairment had been expected fromexposures during pregnancy. Nor had a “discernible increase in heritable disease among thedescendants of those exposed from the accident” (paragraph 224 of [U2]) been expected. No
discernible radiation-related increases in rates of leukaemia or breast cancer (two of the mostradiogenic cancer types), nor in other types of solid cancer besides possibly thyroid cancer, hadbeen expected. A large excess of thyroid cancer due to radiation exposure, such as occurred
after the Chernobyl accident, could be discounted, because the estimated thyroid doses due tothe FDNPS accident were substantially lower than those sustained around Chernobyl. However,the sensitive ultrasound-based thyroid screening of those aged 18 years or younger 12 at the timeof the accident had been expected to detect a large number of thyroid cysts and solid nodules,
including a number of thyroid cancers “that would not normally have been detected without
such intensive screening” (paragraph 225 of [U2]). However, similar even slightly higher rates
of cysts and nodules had been found in the prefectures of Aomori, Yamanashi and Nagasaki
that had not received significant radionuclide deposition from the accident. The substantial
numbers that had already been observed in the Fukushima Health Management Survey(FHMS) 13 had been considered likely to be due to the sensitivity of the screening and not toradiation effects.
12Previous white papers had reported that screening was of those under 18 years old at the time of the accident,
but this has subsequently been clarified as those aged 0–18 years at the time of the accident.
13
The Fukushima Health Management Survey is a large programme of health questionnaires and health screening
conducted by Fukushima Medical University with Japanese government funding. The FHMS includes: acomprehensive health check, and lifestyle and mental health assessment, for all residents from the evacuation
zones; recording of all pregnancies and births among all women in the prefecture who were pregnant on 11 March
2011; and repeated thyroid ultrasound examinations for all children of the prefecture of ages 0–18 at the time of
the accident.

262017 WHITE PAPER

106. Among FDNPS emergency workers, deterministic effects had been considered unlikely,
but the Committee had not been able to preclude the possibility of hypothyroidism, or to assess
the risk of cataracts (owing to insufficient information on doses to the lens of the eye from beta
irradiation). Although 2−3 excess cancers could be inferred over the lifetime among the
173 workers with doses greater than 100 mSv (mainly from external exposure), the Committee
had considered it unlikely that such increased incidence of cancer due to irradiation would bediscernible. The Committee had judged the magnitude of any inferred risk of thyroid cancer
among workers to be such that any increase in incidence due to radiation exposure would likely
not be discernible.
107. The Committee had noted that the major health impacts that had been observed among
the general public and among workers were mental health problems and impaired social wellbeing [U4]. The Committee did not assess health effects unrelated to radiation exposure:estimation of the occurrence and the severity of such health effects was beyond theCommittee’s mandate.
B.

Findings of review of new publications

108. The Committee concluded in the first and second white papers that its findings in thisarea of the 2013 report remained valid and were largely unaffected by new information that
had since been published. A study reviewed in the second white paper which appeared tochallenge the Committee’s findings regarding radiogenic thyroid cancer risk was found to beseriously flawed.
109. Of the publications considered in this third digest, 20 have been reviewed in detail. The
publications served to strengthen or complement the findings of the 2013 report. Threepublications [N2, S14, S15] provided updated information on thyroid cancer screening in the
FHMS programme of clinical and ultrasound examinations among those who were aged
18 years or younger at the time of the FDNPS accident, focusing on the detection rates ofthyroid cysts, nodules and cancers in Fukushima Prefecture. They demonstrated an appreciable
elevation, caused by sensitive ultrasound screening, in the number of detected thyroid cancers.
Three publications [O5, S14, S15] compared the rates of thyroid cancer detection in areas of
Fukushima Prefecture that had received relatively high, medium or low levels of radiation
exposure. One publication [K1] reported on the biological modelling of two different pathways
for thyroid cancer development, distinguished by expression levels of a particular gene that
tend to differentiate sporadic from radiogenic papillary thyroid cancers. Of note is a publication[Y7] describing plans for the study of the FDNPS worker cohort.
110. The first round of screening of 300,476 children and adolescents aged 18 years or
younger at the time of the FDNPS accident has now been completed with a high participation
rate (81.7%). The results are reported in several papers. Two papers [S14, S15] reported that
2,294 individuals had nodules larger than 5 mm, cysts larger than 20 mm, or needed
confirmatory examination based on clinical and ultrasound examination. Nagataki [N2]indicated 116 confirmed or suspected thyroid cancers (38.6 per 100,000) based on fine needle
aspiration cytology (FNAC); 102 of these cases were subject to surgery and 100 cases werediagnosed as papillary thyroid cancers, one as a poorly differentiated cancer, and one as abenign tumour. There was a skewed distribution of tumour sizes, with a mean of 13.9 mm(range 5.1–45 mm). The mean age at exposure to 131I from the accident was 14.9 years for the
thyroid cancer cases, with no case younger than 6 years. All the papillary cancers were of theclassical type [S15]; in contrast, following the Chernobyl accident, the solid variant type was
frequently found in irradiated children [Z1]. A second round of screening has examinedDEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 27

270,379 individuals (as of 30 June 2016), most of whom were included in the first round, anddetected an additional 59 (21.8 per 100,000) suspected thyroid cancers by FNAC [N2].
111. Several papers compared the prevalence of thyroid cancer in areas of Fukushima
Prefecture with a range of levels of exposure to radionuclides released as a result of the accident.
Neither Ohira et al. [O5] nor Suzuki [S14] found any statistically significant differences inthyroid cancer prevalence for those from the highest or middle exposure areas, compared to thelowest exposure area. For example, Suzuki found thyroid cancer prevalences of 33, 39 and 35 per
100,000 in the highest, medium and lowest-exposure areas within Fukushima Prefecture,
respectively. When Suzuki et al. [S15] further subdivided the low exposure area into low andlowest, the odds ratios (ORs) were all non-significant: 1.22 (95% CI: 0.55, 2.7), 1.21 (95% CI:
0.64, 2.3), 1.19 (95% CI: 0.58, 2.4) for the high (evacuation zone), medium and low exposureareas, respectively, compared to the lowest exposure area. Though these papers divided theexposure areas differently, none of them found any relationship between thyroid cancer
prevalence and exposure level. Katanoda et al. [K3] reported that the observed prevalence of
thyroid cancer in the FHMS compared to the expected prevalence was about 20-fold higher,
which the authors attributed to an ultrasound screening effect, because the thyroid doses andother considerations make it implausible that it was an effect of radiation exposure.
112. Ohira et al. [O5] compared the estimated doses from external exposure for the
56 thyroid cancer cases with those for the remainder of the subset of about 129,300 of thosescreened for whom individual doses had been estimated. Compared to those with estimateddoses from external exposure of less than 1 mSv, the ORs for risk of thyroid cancer were 0.76
(95% CI: 0.43, 1.35) for those with estimated doses in the range 1 to 2 mSv, and 0.24 (95% CI:
0.03, 1.74) for those with estimated doses greater than or equal to 2 mSv. Suzuki et al. [S15]indicated that, of 63 confirmed or suspected thyroid cancer cases with estimated doses fromexternal exposure, 71% had doses less than 1 mSv and none had doses greater than 2.2 mSv.
However, similar, more meaningful, comparisons cannot be made for doses to the thyroid,
because no estimates of these are available. In the absence of thyroid doses, caution should be
exercised in interpreting the results of Ohira et al. [O5].
113. Other papers highlighted concerns about possible over-diagnosis of thyroid cancer
because of sensitive thyroid screening of general populations with ultrasound and about
aggressive treatment of small thyroid cancers. From international temporal trends in thyroid
cancer incidence, Vaccarella et al. [V1] showed the effect of large-scale screening in increasing
thyroid cancer incidence in Australia, the Republic of Korea, the United States, and a numberof countries in Europe. Park et al. [P1] analysed extensive thyroid cancer data from a numberof clinics in the Republic of Korea from 1999 and 2008, during which time there was a large
increase in thyroid cancer incidence in the country. They estimated that about 94% of theincrease in incidence was due to the national programme to promote population ultrasoundscreening. In 2014, when a public awareness campaign against routine population screening
was initiated in the Republic of Korea, the number of cases of thyroid cancer surgery fell by 35%
in one year. Leboulleux et al. [L1] pointed out that many of the small papillary thyroid cancers
found by ultrasound screening have indolent, benign behaviour. Since surgery has monetary
costs and potential medical and psychological risks, they advocated “watchful waiting” rather
than surgery for some small cancers; however, no consensus has been achieved regarding thissuggestion. Nagataki [N2] recommended further research to identify molecular markers thatcan distinguish aggressive from indolent papillary thyroid cancers.
114. Thyroid screening is a complex issue and judgements on its scope, nature and/or continuation
following the accident at FDNPS require considerations of factors that go far beyond the purely
scientific issues alone (e.g. those of a socio-economic, public health, legal, ethical or human282017 WHITE PAPER

rights nature). 14 Should the screening continue, the systematic collection and storage of biopsy
material (including related information on exposures) and open access to it for meritorious
research, would help investigations to be made of biomarkers and molecular signatures ofradiation-induced thyroid cancer (i.e. in a similar manner to the Chernobyl Tissue Bank).
115. Kaiser et al. [K1] put forward the hypothesis that childhood radiation-induced thyroid
cancer develops in a multistage pathway that is distinct from the carcinogenesis pathway ofsporadic thyroid cancers (in contrast to the single-pathway hypothesis of Williams [W5]). Theymodelled the Chernobyl thyroid cancer data and found that over-expression of the CLIP2 genestatistically distinguished radiation-associated thyroid cancers occurring before age 20 fromsporadic ones. Future research to find and model predictive biomarkers for radiogenic thyroid
cancer may shed new light on the pathogenesis of radiogenic thyroid cancer.
116. One paper purported to show increases in perinatal mortality associated with radiation
exposure by comparing prefecture-wide rates before and after the FDNPS accident, usingsophisticated modelling methods [S8]. However, the study is flawed in that the authors
designated six prefectures as a “severely contaminated” area for comparison with other areas,
whereas most of those prefectures received radiation exposures from the accident that were
small compared to normal background radiation exposure. In addition, as the authors admit,
this was an observational study that does not allow causal inference.
117. A study of self-reported psychological distress among those evacuated as a result of the
FDNPS accident showed a positive correlation between radiation levels in their home locality
and the frequency of distress [K13]. However, as noted in the 2013 report, psychologicaldistress is a general indirect effect of catastrophic events and should not be attributed toradiation exposure itself; such effects do not fall within the Committee’s mandate.
118. A number of papers have compared health changes in evacuees from before theirevacuation with afterwards or according to the duration of evacuation [E1, H3, O2, O3, O4].
They observed increases in such health conditions as the frequency of metabolic syndrome,
dyslipidaemia, hypertension, weight gain, psychological distress and alcoholism that could be
associated with evacuation. Of particular concern was the documented increase in mortality
among the institutionalized elderly within the first year after evacuation 15 [Y8]. The
Committee recognizes that these can be indirect effects of evacuation, stress and associatedlifestyle changes, consequent to a radiation accident or other catastrophe, but such effects ofevacuation are beyond the scope of the Committee’s considerations.
119. In 2016, the Japanese government awarded compensation to two occupationally
exposed nuclear power plant workers. Both had been employed at FDNPS following theaccident where they had accumulated part of their exposure. One was diagnosed withleukaemia and the other with thyroid cancer. The Committee has informed on the elements ofscientific attribution of malignancies to radiation exposure (see annex A of the 2012 report[U3]). Scientific attribution is not equivalent to legal imputation in an occupational context.
Therefore, the granting of these awards (and, likewise, others granted previously or in the
future to occupationally exposed workers) does not imply a scientifically proven cause–effectrelationship between radiation exposure and any particular case of cancer. Rather, it is the14

Broader issues relevant to decisions on the continuation and/or implementation of thyroid screening in the
Fukushima Prefecture have been addressed in various forums, for example, [Y4] and [N5].
15
Including 12 people who died in transit during the evacuation and 50 who died as refugees immediately after
transport.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 29

result of the application of a scheme, 16 developed several decades ago by the Japanese
government, for industrial accident compensation insurance [M8]; knowledge andunderstanding of the effects of radiation has since improved considerably.
120. Experts convened by the MHLW have planned a long-term epidemiological and healthmonitoring study of FDNPS emergency workers [Y7]. Accurate cumulative measures ofradiation dose, before, during and after the FDNPS emergency work, are to be obtained. The
study plans to maintain a long-term follow-up of the approximately 20,000 workers, withperiodic, well-standardized health examinations. The experts recommended that standard
health data on the indicators measured and the laboratory tests carried out as part of thecompulsory annual medical examination be compiled every year, and that a thyroid ultrasoundexamination, lens opacity examination and special tests for kidney function, infectious diseases
and systemic inflammation be conducted every 3-5 years for those workers exposed to over
100 mSv as a result of the accident. The thyroid outcomes of interest include thyroid cancer,
hypothyroidism and autoimmune thyroiditis. The experts also recommended that questionnaire
information should be obtained periodically on potential confounding factors: medical history,
lifestyle and socio-demographic data, psychological stresses, and exposure to other toxic
agents. They further recommended that arrangements be made to link the workers to the
MHLW national mortality (cause of death) database and the new national tumour registry.
Storage of part of the blood samples was also suggested for assessing future markers of diseaseor for other research purposes. To help prevent arbitrary statistical analysis, they recommended
that researchers report the full set of both statistically significant and null differences.
121.

The Committee has the following concerns relating to the scientific value of this study:(a) Because only 173 workers received as much as 100 mSv during emergency
operations, the statistical power of the study will likely be too low to fulfil the study’s
aspiration to distinguish cumulative dose from dose-rate effects, although information on
additional occupational radiation exposure before and after emergency operations, plus
medical exposures, will be obtained to estimate lifetime doses;(b) The study may be compromised by low participation rates, given that radiation
workers are already receiving compulsory annual medical examinations, and that contract
radiation workers are very transient and it may be difficult to keep track of their
whereabouts.

16

In 1976, the Japanese government established the basis for the award of compensation to occupationally
exposed workers through the Industrial Accident Compensation Insurance scheme [M8]. The initial focus of thescheme was leukaemia. According to this scheme, leukaemia may be deemed eligible for medical compensation
by a medical review panel if the dose was at least 5 mSv times the number of years between (first) exposure anddiagnosis of the malignancy. A similar scheme applies for certain other lympho-haematopoietic malignancies withmodification based on their comparative radiosensitivity. Up to the end of 2016, some 15 nuclear power plant
workers in Japan had been granted compensation under this scheme for lympho-haematopoietic malignancies, ofwhich about half were leukaemia. Two of these 15 workers were employed at FDNPS following the accident.
Solid cancer may be deemed eligible for medical compensation by a medical review panel if the effective dose
was at least 100 mSv, the time between (first) exposure and diagnosis of the malignancy was 5 years or more, andthere was no other aetiology than radiation. These criteria are kept under continuing review and may be revised inlight of new scientific evidence. In 2016, one worker was granted compensation for thyroid cancer; he was in his
forties, had been involved in with work on radiation since 1992, including employment at FDNPS between
March 2011 and April 2012, and his cumulative effective dose was about 150 mSv, of which 139 mSv wasreceived while working at FDNPS.

30

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Despite the potentially limited scientific value of the study, the Committee acknowledges thatit may be considered justified to address the health concerns of the workers affected.
C.

Potential implication of new publications

122. The Committee has concluded that its findings regarding health effects of radiation
exposure from the FDNPS accident in the 2013 report remain valid and are largely unaffectedby new information that has since been published.
123. The Committee has noted, and will remain abreast of, ongoing research andinvestigations into the health implications of the accident, as reported from the FHMS being
carried out in Fukushima Prefecture and other sources. It has identified the following specificareas, in particular, where further data or information would have the potential to contribute toaddressing the research needs identified in the 2013 report:(a) Provision by the FHMS of more detailed breakdowns of the numbers of young
people screened, and of confirmed/suspected thyroid cancers by tumour size, and by age at
irradiation, age at screening, and sex, because this would permit more accuratecomparisons with parallel data from young people screened but unexposed;(b) Completion of estimation of dose from external exposure for the young people in the
FHMS thyroid screening study, especially those with suspected or confirmed thyroid
cancers; this would permit an improved analysis by exposure level that would provide astronger basis for inference than comparisons with other populations who may differ fromthe FHMS study in age, sex, screening protocols and other factors;(c) Linkage of outcome information—including mortality and incidence of thyroid
cancer, other cancer and non-cancer diseases, birth defects, and clinical and laboratory
findings—with radiation exposure and information on age, sex and other risk factors, topermit the most informed assessment of health experience and risk; this would maximize
the capability to address important questions that both scientists and the public may have;(d) Provision of systematic data on the health of the FDNPS emergency workers, withcooperation by the government and nuclear industry to facilitate a high follow-up rate, so
as to develop a high-quality assessment of potential radiation effects, while also
considering possible confounding by lifestyle, toxic exposures and pre-existing medical
conditions.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 31

IX. UPDATES ON EVALUATION OF DOSES AND EFFECTS FOR
NON-HUMAN BIOTA
A.

Recapitulation of the 2013 report124. The Committee had estimated radiation doses due to the accident to non-human biota
through applying suitable models. The corresponding estimates of effects due to the radiation
exposure had then been inferred by synthesizing the Committee’s generic evaluations of dose–
effect relationships. Exposures of both marine and terrestrial non-human biota following theaccident had been, in general, too low for acute effects to be observed, although some
exceptions had been considered possible because of local variability. The Committee had
concluded that, in general, population-relevant effects on non-human biota in the marine
environment would have been confined to areas close to where highly radioactive water wasdischarged and released into the ocean. Although the Committee had been unable to exclude arisk of effects to individuals of certain terrestrial species, in particular mammals, it had
considered observable effects at the population level to be unlikely. It had concluded that any
radiation effects would have been constrained to a limited area where the deposition density ofradioactive material was greatest, and that, beyond this area, the potential for effects on biota
was insignificant.
125. The Committee had made reference to studies in which effects in various terrestrial
biota had been observed in areas with enhanced levels of radioactive material as a result of the
FDNPS accident [H8, M9, M10]. It had noted that the substantial impacts reported for
populations of wild organisms from these studies were inconsistent with the main findings of
the Committee’s theoretical assessment. The Committee had expressed reservations about
these observations, noting that uncertainties with regard to dosimetry and possible confounding
factors made it difficult to substantiate firm conclusions from the cited field studies.
B.

Findings of review of new publications

126. The Committee concluded in the first and second annual white papers that its findingsin this area of the 2013 Fukushima report remained broadly supported by the available
evidence. However, it recognized potential limitations in its approach owing to reliance largely
on laboratory-based rather than field studies. It identified a need for multidisciplinary fieldstudies tailored to analyse the impacts of ionizing radiation on populations of wild organisms
interacting under the conditions prevalent within ecosystems in areas with enhanced levels ofradioactive material.
127. Of the publications considered in this third white paper, 21 have been reviewed in detail.
The main implications of the findings of these publications are summarized below.
128. Several authors [T6, V2, V3] have applied kinetic transfer models to releases from the
FDNPS accident to provide further insights into the temporal evolution of radionuclide
concentrations in different environmental compartments. Tateda et al. [T6] carried out ananalysis that they believed indicated that the observed slow decline of concentrations of 137Cs
in benthic fish off southern Fukushima could be explained by radiocaesium transfer to such
fish from benthic invertebrates via ingestion. Vives i Batlle et al. [V3] provided an overview ofan intercomparison that was undertaken for eight models (including one steady state model and322017 WHITE PAPER

two kinetic models used in the 2013 report) designed to predict the radiological exposure ofmarine biota. The inter-comparison showed that, although there was, in some cases, significant
variability between the models because of parameter and methodological differences, thepredictions for some key indicators of exposure, e.g. radiocaesium concentrations in mostorganisms, were remarkably similar (often within one order of magnitude). This suggests thatboth kinetic models used in the 2013 report provided reasonably robust predictions of marine
biota exposures in the initial period post-accidental release.
129. Several reviewed papers concerned studies of the concentrations of radionuclides in,and their transfer to, non-human biota [A3, F3, T1, T2, T4, W1, W2]. The results weregenerally consistent with the input data sets used for the environmental impact assessment
carried out for the 2013 report, having, in some cases, been drawn from the same or related
information sources. All of the above-mentioned studies, including the kinetic transfer
modelling work, as well as other more indirectly relevant studies on transfer [S12, U1] andpost-deposition processes [S5, T3], may be useful in refining the models used in the 2013
report in any follow-up assessment.
130. Qiu et al. [Q1] presented data on concentrations of radiocaesium and radiosilver inwharf roaches (Ligia sp.) sampled from various coastal locations, including the coast of
Fukushima Prefecture, in 2011 and 2012. Samples generally contained low levels of theradionuclides—rarely exceeding 100 Bq/kg fresh weight—and therefore much lower thanthose assessed in the 2013 report. However, the study of Qiu et al. [Q1] indicated that
substantial bioaccumulation of 110mAg may have occurred in some locations: a 110mAg:137Cs
activity ratio in excess of one was found for one Fukushima Prefecture coastal location (which
is about one to two orders of magnitude greater than the ratio in coastal sediments). Given thatsilver has a relatively high concentration ratio for fish, it is therefore plausible that 110mAg may
have been more important than assumed in the 2013 report. Horiguchi et al. [H10] alsomeasured relatively elevated concentrations of 110mAg in shellfish, but the 110mAg:137Cs ratios
were even higher in this study: for example, 110mAg:137Cs ratios in the limpet and rock shellwere reported as being 1.5–54.2 and 13.6–15.7, respectively. However, in view of therelatively low 110mAg concentration in marine sediment relative to 137Cs noted by IAEA [I1]and 110mAg:137Cs ratios in marine biota rarely exceeding unity as noted by Qiu et al. [Q1], theelevated values of 110mAg as reported by Horiguchi et al. [H10] appear to be outliers and would
benefit from further investigation.
131. Two papers [T2, V2] appeared to support the finding of the 2013 report that thecontribution of radionuclides in marine sediment to exposures of marine biota in the initialperiod after the accident was negligible compared to other sources.
132. Okano et al. [O10] studied large Japanese field mice (Apodemus speciosus) in
Fukushima Prefecture, focusing on apoptosis in germ cells and abnormal sperm morphologies.
They concluded that radiation exposure did not cause substantial male subfertility during 2013
and 2014. The study provides evidence to support the main findings of the 2013 report that
regional population impacts on non-human biota were not likely. However, the sampling sites
used in the study were generally not in the areas of highest radionuclide deposition, although
one site was in a location with ambient dose equivalents (30 months after the accident)
exceeding 10 µGy/h.
133. Horiguchi et al. [H10] studied population densities and diversity of various intertidalorganisms (e.g. echinoderms, crustaceans, and bivalves) in coastal regions along the easternJapanese seaboard in the environs of FDNPS in the period 2011–2013. The authors found thatthe number of intertidal species decreased significantly at coastal locations closer to FDNPS.

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 33

Furthermore, no rock shell (Thais clavigera) specimens were collected within a distance ofapproximately 30 km from FDNPS in 2012. The fact that this particular species of gastropod
was observed at many other sites affected by the tsunami suggested to the authors that there
was a clear causal link between the absence of this organism and the FDNPS accident. The
number of species and population densities in the intertidal zones, surveyed in 2013, weremuch lower at sites near, or within several kilometres south of, FDNPS compared to othermore distant sites, and lower than in 1995, especially in the case of arthropoda. Nonetheless,the authors of this work also highlighted the complexity of establishing a definite causal linkbecause of various potential direct impacts, such as physical harm from the tsunami, andtoxicity from chemicals and radionuclides in the releases that occurred immediately after theaccident. There also appear to be some questions regarding radionuclide determinations in thisstudy, given the extremely high relative values of 110mAg that have been reported (seeparagraph 130 above). Nonetheless, the results of the biological survey, per se, appear to berobust and provide further support to the argument that the assessment in the 2013 report may
have been simplistic in not accounting for ecosystem complexity when quantifying
environmental risk.
134. Hiyama et al. [H9] provided further evidence to suggest that the high abnormality rates
observed in the pale grass blue butterfly were induced by “anthropogenic radioactive
mutagens”. However, Otaki [O12] synthesized the results from several studies of the effects on
the same species of butterfly following the FDNPS accident, and reported that ionizing
radiation was unlikely to be the exclusive source of the environmental disturbances observed.
135. Yoschenko et al. [Y9] observed significant increases in morphological abnormalities inyoung trees of the species Japanese red pine (Pinus densiflora) in areas with elevatedradionuclide deposition densities following the FDNPS accident. This is consistent with earlier
studies [W4] reported in the second white paper [U5], which found morphologicalabnormalities in Japanese fir trees. As noted in the second white paper [U5], accumulated
doses in vegetation in areas with relatively high densities of deposited radionuclides were
estimated in the 2013 report to be similar to those at which disturbances in growth,
reproduction and morphology of conifers had been observed following the Chernobyl accident.
The implications of the presence of morphological abnormalities on tree population integrity is
not well established.
C.

Potential implication of new publications

136. The Committee’s assessment of the transfer of radionuclides released as a result of the
FDNPS accident to non-human biota and consequent environmental exposures remains broadly
supported by numerous publications. Although the study of Horiguchi et al. [H10] potentiallychallenges the findings of the 2013 report in the observation of large population level impacts
in the intertidal zone, there are questions over some of the data presented in this work that need
to be resolved, as noted above, before definitive conclusions can be drawn. Geras’kin [G1]noted that there does seem to be mounting evidence to suggest that radiation exposure canresult in disruption of ecological interactions between components of ecosystems, which may
act as a trigger of perturbation and lead to consequences that may differ from those expectedfrom direct effects observed at the organism level. As noted in earlier white papers [U5], there
may be questions in relation to how calculated dose-rates are interpreted, and, in particular,
whether it is sufficient to focus on end points that do not take full account of the complexity of
ecosystem interactions. The identified need for follow-up studies investigating the dose
response at higher levels of biological organization (e.g. the population level) which take due
account of biota interactions within ecosystems remains valid.

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X. CONCLUSIONS OF APPRAISAL OF NEW PUBLICATIONS
137. Of the new sources of information appraised for this third white paper, a large
proportion confirmed one or other of the major assumptions in the 2013 report. Nonematerially affected the main findings in, or challenged the major assumptions of, the 2013
report. Those that had the potential to do so, albeit subject to further analysis or confirmationfrom studies of better quality, are summarized briefly below.
A.

Potential challenges to 2013 report138. The study of Horiguchi et al. [H10] potentially challenges the findings of the 2013
report in the observation of large population level impacts on non-human biota in the intertidal
zone. However, there are questions over some of the data presented in this work, which need tobe resolved before definitive conclusions can be drawn. Further studies [G1, H9, O12] haveadded to the evidence suggesting that irradiation can result in disruption of ecologicalinteractions between components of ecosystems. Studies that take due account of biota
interactions within ecosystems continue to be needed.
B.

Contributions to research needs

139. Table 1 summarizes those publications that have been judged to have made asignificant contribution to addressing the research needs identified in the 2013 report. Progress
is being made in many areas, but several of those research needs have yet to be addressed fullyby the scientific community (at least in peer-reviewed publications).

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 35

Table 1. Publications considered to make a significant contribution to one or other identified
research need
Research need

Publications deemed to makea high contribution toresearch need

Publications deemed to makea medium contribution toresearch need

RELEASES TO ATMOSPHERE, DISPERSION AND DEPOSITION
Improve estimates of amount and characteristics ofreleases to atmosphere as a function of time

[C2, S7, S9, T8][F1, G2, H7, J1, K2, M5,
M7, O1, S1, S4, S10, Y1,
Y10]

RELEASES TO WATER, DISPERSION AND DEPOSITION
Measure and improve characterization of leaks ofradioactive water and releases to aquatic environment
over time[C1, F2, I4, T10]

Forecast and quantify long-term transport and mixing of
releases and consequent exposures through aquatic
pathways[K11, K12]

[I5]

TRANSFER THROUGH TERRESTRIAL AND FRESHWATER ENVIRONMENTS
Collate relevant information on transfer parameter values
for food chain pathways[K8, M11, W2, Y2][D1, E3, E4, F4, I3, K7, K9,
K14, M6, M12, O6, O9, S13,
T1, U1, W3, W6, Y3, Y5]

DOSES TO THE PUBLIC
Measure dose rates due to external exposure to depositedmaterial in various environments, forecast and trackchanges over time and quantify impact of environmental
remediation programmes[M3, N3]

Conduct in vivo measurements of radionuclides inpeople to support refinement in the estimation of doses
and their distribution and to estimate current and futurelevels of exposure[K5, K6, T5]

DOSES TO WORKERS
Quantify the uncertainties in reported doses to workers,
considering the work histories of individual workers[S3, Y6, Y7]

HEALTH IMPLICATIONSContinue the ongoing health survey in Fukushima
Prefecture
Analyse and quantify the impact of ultrasonographic
surveys on the apparent incidence of thyroid cancer inFukushima Prefecture

[N2]

[S2]

[O5, S14, S15]

DOSES AND EFFECTS FOR NON-HUMAN BIOTA
Measure and assess the environmental exposures typicalfor certain species of non-human biota, and further
analyse whether radiation exposure was an importantfactor in causing environmental effects reported in fieldstudies but which were inconsistent with theCommittee’s assessment[H9, H10, O10, T1, W1, W2,
Y9][A3, F3, O12, Q1, S12, T2,
T4, V2, V3]362017 WHITE PAPER

XI. COLLECTION AND EVALUATION OF MAJOR RESEARCH
PROJECTS AND PROGRAMMES
140. One of the specific objectives in the plan for follow-up activities (see paragraph 4) was“to collect and evaluate progress made in, and plans for, major research projects andprogrammes related to pending questions”. This objective was not addressed systematically ineither of the previous white papers, where the focus was on the review of publishedinformation. Awareness and/or the evaluation of on-going and planned major research projects
or programmes will be beneficial for the Committee’s follow-up activities in two respects:
firstly, in providing advance warning of studies, the outcomes of which may have a material
impact on the findings of the 2013 report; and, secondly, in better informing judgements on if,
and if so when, it may be appropriate to update the 2013 report, i.e. moving from Phase I(review of new information) to Phase II (update of the 2013 report) of the plan for follow-up
activities (see paragraph 4).
141. Research projects and programmes being carried out, or funded by, Japaneseorganizations represent by far the majority of ongoing and planned research on the accident at
FDNPS. These have been evaluated based on meetings with the Japanese research community.
142. Two meetings were held with the Japanese research community in November 2016.
The purposes of the meetings were: to exchange views on gaps, uncertainties and researchneeds that had the potential to improve assessments of the health and environmental impact of
the accident at FDNPS; to become better informed of major Japanese research
projects/programmes, in particular their scope, objectives, current status, envisaged outcomes
and duration; and to establish mechanisms to enable effective dialogue and exchange of
information between the Committee’s experts and the Japanese research community. One
meeting was held in Tokyo for those projects/programmes being carried out or funded at anational level; a second meeting was held in Fukushima City for those projects/programmes
being carried out largely under the auspices of the Fukushima Prefecture. Members of theCommittee’s Expert Group and Japanese Working Group attended both meetings, together
with lead researchers for each project/programme and representatives of a number oforganizations that had commissioned/funded the research.
143. The scope, content and outcomes of these meetings are briefly described in anelectronic attachment to this white paper. Particular attention is given to the extent to which theresearch projects/programmes address the research needs identified in the 2013 report. Table 2
presents a summary of the major Japanese research projects/programmes, setting out the main
objectives, the envisaged outcomes which address these research needs and the timescales foreach. It is based on information initially compiled by the Committee’s Japanese Working
Group supplemented by information presented during the two meetings. Many of the research
projects/programmes, at least as currently formulated, will be completed within the next few
years (i.e. before 2020) and have the potential to enhance significantly the quality, robustness
and/or comprehensiveness of current estimates of, inter alia: the magnitude and characteristicsof the release of radioactive material, the doses to the public resulting from the accident at
FDNPS, and the health implications.

Objectives

To make best use of databases of measurements ofconcentrations of radioactive material in the air and
ATDM to better quantify concentrations in air where
people were located during the accident, and,
thereby, assess inhalation doses in the early phases of
the accident

Address uncertainties in the source term andmodelling by using improved ATDM results,
measurement data on dose rates in air, and an
updated source term
Reconstruct doses to members of the public (inparticular, in the early phases of the accident) frominternal and external exposure

Create maps of the dose rate in air and radionuclide
deposition density
Clarify the characteristics of deposition
Study radiocaesium migration in the environment
Develop a model to predict the air dose rate
distribution
Make data available to the public

Characterize releases to the aquatic environment,
including groundwater, and ultimately the Pacific
Ocean, over time
Forecast and quantify the long-term transport andmixing of these releases
Assess consequent exposures through aquatic
pathways

Assess the migration of radionuclides in theterrestrial environment

Short description of research
programme (Sponsor or Lead)

Interdisciplinary study on inhalation
exposure and risk assessment based on
measured concentrations ofradionuclides in air following thenuclear accident(Ministry of the Environment, MOE)

Comprehensive study to assess radiation
doses to residents from the FDNPS
accident(MOE)

Survey on the distribution of radioactive
materials(Ministry of Education, Culture, Sports,
Science and Technology, MEXT,
Nuclear Regulation Authority, JAEA)

Studies on releases of radioactive waterfrom the FDNPS accident to the ocean
environment(JAEA)

Studies on the transfer of radionuclides
in the terrestrial environment(MEXT, JAEA)

Table 2. Major Japanese research projects and programmes

Calculation tools and parameter values formodelling transfers of radionuclides in theterrestrial environment in Japan

Releases to the ocean by source (direct
releases, deposition from the atmosphere,
inputs from rivers and groundwater) and overtime
Understanding of transport and dispersion in
the ocean

Maps of dose rates in air and radionuclide
deposition densities on the ground
Improved understanding of how deposition
occurred and how it varied in time and space
Predictions of air dose rates up to 30 years
after the accident
Publicly available database integrating various
environmental monitoring data

New source term for releases to theatmosphere
Improved estimates of doses to members of
the public, particularly in the early phases of
the accident, from inhalation, ingestion andexternal exposure

Improved estimates of doses to members of
the public from inhalation and theiruncertainties

Key outcomes addressing UNSCEAR researchneeds

2018, with outcomesof further research tofollow

Mid-2019

Research continuingwith publication as
appropriate

Mid-2017

Mid-2018

Results envisaged by

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 37

Objectives

Understand radionuclide transport in the terrestrial
and aquatic environment, the physiochemical formsof radionuclides, the long-term behaviour ofradionuclides in rivers, reservoirs and the marine
environment, and the long-term behaviour ofradionuclides in the ecosystem
Assess the effects of chronic exposure of wildlife
populations to radiation from the accident

Understand the effects of the radioactive materials
released from FDNPS on natural ecosystems

Provide dose estimates for the residents ofFukushima Prefecture, including estimates of thedose from external exposure for the first four months
after the FDNPS accident
Assess and monitor the health and well-being ofresidents of Fukushima Prefecture through acomprehensive health check for people living inevacuation areas, thyroid screening for all children in
the prefecture, monitoring of mental health andlifestyle changes, and a pregnancy and birth survey

Estimation of individual doses and monitoring thehealth status of emergency workers including
estimates of doses from external and internal exposure
during the emergency period, a comprehensive healthcheck-up, thyroid screening by ultrasonography, acataract (lens opacity) study, a mental health survey,
and storage of biological samples

Short description of research
programme (Sponsor or Lead)

Studies on radionuclide transport in theterrestrial and aquatic environment andexposure of wildlife(Fukushima University)

Studies on the radiation effects on wild
animals and plants(MOE)

Fukushima Health Management Survey(Fukushima Prefecture and Fukushima
Medical University)

Nuclear Emergency Workers Health
Study(MHLW, Radiation Effects Research
Foundation)

Improved estimates of doses to workers frominternal and external exposure
Evidence on changes in health and well-beingof workers

Estimates of doses to members of the publicfrom internal exposure and from external
exposure
Evidence on changes in health and well-being

Assessment of the exposures of non-humanbiota and effects as a result of the FDNPS
accident

Parameter values for modelling transfers ofradionuclides in the terrestrial and aquatic
environments in Japan and for estimating
doses to members of the public from ingestionof foodstuffs
Improved estimates of long-term doses to andeffects on non-human biota

Key outcomes addressing UNSCEAR researchneeds

Baseline survey
expected complete in2019

Research continuingwith publication as
appropriate

2012 to 2015 survey
reported in 2016.
Research continuingwith publication as
appropriate

Research continuingwith publication as
appropriate

Results envisaged by

38 2017 WHITE PAPER

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 39

ACKNOWLEDGEMENTS
In approving this white paper for publication, the Committee wishes to acknowledge withgratitude the help of the experts directly involved in undertaking follow-up activities relating tolevels and effects of radiation exposure due to the nuclear accident after the 2011 great eastJapan earthquake and tsunami.
Senior technical advisers
W. Weiss (Germany) and M. Akashi (Japan)
Expert group
M. Balonov (Russian Federation), C. Estournel (France), G. Etherington (United Kingdom),
F. Gering (Germany), B. Howard (United Kingdom), R. Shore (United States), S. Solomon(Australia), P. Strand (Norway)
Japanese working group
Technical support: K. Kodama (Japan)
Members: T. Aono (Japan), M. Chino (Japan), K. Ozasa (Japan), S. Saigusa (Japan), K. Sakai(Japan), T. Takahashi (Japan), H. Yasuda (Japan)
Critical reviewers
J. Brown (United Kingdom), J. Chen (Canada), N. Harley (United States), G. Hirth (Australia),
J.-R. Jourdain (France), F. Mettler (United States), B.I. Min (Republic of Korea), H. Nies
(Germany), S. Shinkarev (Russian Federation), K.S. Suh (Republic of Korea), H. Vandenhove(Belgium)
Project manager
G.N. Kelly (United Kingdom)

REFERENCES
A1

A2

A3

A4

A5

B1

C1

C2

D1

E1

Abe, Y., Y. Iizawa, Y. Terada et al.
Detection of uranium and chemical state
analysisofindividual
radioactive
microparticles emitted from the Fukushima
nuclear accident using multiple synchrotron
radiation X-ray analyses. Anal Chem
86(17): 8521-8525 (2014).
Adachi, K., M. Kajino, Y. Zaizen et al.
Emission of spherical cesium-bearing
particles from an early stage of the
Fukushima nuclear accident. Sci Rep 3:2554 (2013).
Aono, T., Y. Ito, T. Sohtome et al.
Observation of radionuclides in marine
biota off the coast of Fukushima prefecture
after TEPCO's Fukushima Daiichi nuclear
power station accident. pp.115-123 in:Radiation Monitoring and Dose Estimationof the Fukushima Nuclear Accident.
(S. Takahashi, ed.) Springer, Tokyo, 2014.
Aono, T., S. Yoshida and M. Akashi. Initialand present situation of food contaminationin Japan after the accident at the
Fukushima Dai-Ichi nuclear power plant.
Radiat Prot Dosim 171(1): 14-19 (2016).
Arai, T. Radioactive cesium accumulationin freshwater fishes after the Fukushima
nuclear accident. Springerplus 3(1):479-491 (2014).
Brown,J.
andJ.R.
Simmonds.
FARMLAND a dynamic model for thetransfer of radionuclides through terrestrial
foodchains.
NRPB-R273.
National
Radiological Protection Board, Chilton, 1995.
Castrillejo, M., N. Casacuberta, C.F. Breieret al. Reassessment of (90)Sr, (137)Cs, and(134)Cs in the coast off Japan derived fromthe Fukushima Dai-ichi nuclear accident.
Environ Sci Technol 50(1): 173-180 (2016).
Chino, M., H. Terada, H. Nagai et al.
Utilization of (134)Cs/(137)Cs in theenvironment to identify the reactor units
that caused atmospheric releases during the
Fukushima Daiichi accident. Sci Rep 6:31376 (2016).
Djedidi, S., K. Kojima, N. Ohkama-Ohtsu
et al. Growth and (137)Cs uptake andaccumulation among 56 Japanese cultivarsof Brassica rapa, Brassica juncea andBrassica napus grown in a contaminatedfield in Fukushima: Effect of inoculation
with a Bacillus pumilus strain. J Environ
Radioact 157: 27-37 (2016).
Ebner, D.K., M. Ohsawa, K. Igari et al.
Lifestyle-related diseases following theevacuation after the Fukushima Daiichi
nuclearpower
plant
accident:
a

E2

E3

E4

F1

F2

F3

F4

G1

G2

H1

H2

41

retrospective study of Kawauchi Village
with long-term follow-up. BMJ Open 6(7):e011641 (2016).
Eguchi, T., T. Ohta, T. Ishikawa et al.
Influenceofthenonexchangeable
potassium of mica on radiocesium uptake
by paddy rice. J Environ Radioact 147:
33-42 (2015).
Endo, S., T. Kajimoto and K. Shizuma.
Paddy-field contamination with 134Cs and137
Cs due to Fukushima Dai-ichi nuclear
power plant accident and soil-to-ricetransfer coefficients. J Environ Radioact
116: 59-64 (2013).
Evrard, O., J.P. Laceby, Y. Onda et al.
Quantifying the dilution of the radiocesium
contamination in Fukushima coastal river
sediment (2011-2015). Sci Rep 6: 34828(2016).
Fujiwara, H. Observation of radioactive
iodine ((131)I, (129)I) in cropland soil after
the Fukushima nuclear accident. Sci Total
Environ 566-567: 1432-1439 (2016).
Fukuda, M., T. Aono, S. Yamazaki et al.
Dissolved radiocaesium in seawater off thecoast of Fukushima during 2013–2015.
J Radioanal Nucl Chem 311(2): 1479-1484(2016).
Fuma, S., Y. Kubota, S. Ihara et al.
Radiocaesium contamination of wild boars
in Fukushima and surrounding regions after
the Fukushima nuclear accident. J Environ
Radioact 164: 60-64 (2016).
Fuma, S., Y. Watanabe, Y. Kubota et al.
Radiocaesium contamination of bamboo
shoots in Fukushima and surrounding
regions after the Fukushima nuclear
accident. J Radioanal Nucl Chem 311(1):219-223 (2017).
Geras’kin, S.A. Ecological effects of
exposure to enhanced levels of ionizing
radiation. J Environ Radioact 162-163:
347-357 (2016).
Girard, S., V. Mallet, I. Korsakissok et al.
Emulation and Sobol' sensitivity analysis of
an atmospheric dispersion model applied to
the Fukushima nuclear accident. J Geophys
Res Atmos 121(7): 3484-3496 (2016).
Hanna, S.R. and G.S. Young. The need forharmonization of methods for finding
locations and magnitudes of air pollution
sourcesusing
observationsofconcentrations and wind fields. Atmos
Environ 148: 361-363 (2017).
Hashimoto, K., K. Tanoi, K. Sakurai et al.
The radioactivity measurement of milk
from the cow supplied with the meadow

42

H3

H4

H5

H6

H7

H8

H9

H10

H11

I1

I2

2017 WHITE PAPER

grass grown in Ibaraki-prefecture, after the
nuclearpower
plant
accident.
Radioisotopes 60(8): 335-338 (2011).
(Japanese).
Hashimoto, S., M. Nagai, S. Fukuma et al.
Influence of post-disaster evacuation on
incidenceof
metabolicsyndrome.
J Atheroscler Thromb 24(3): 327-337 (2017).
Hirayama, H., H. Matsumura, Y. Namito etal. Estimation of time history of I-131
concentration in air using NaI(Tl) detector
pulse height distribution at monitoring
posts in Fukushima prefecture. Trans At
Energy Soc Japan 14(1): 1-11 (2015).
(Japanese).
Hirono, Y. and K. Nonaka. Time serieschanges in radiocaesium distribution in tea
plants (Camellia sinensis (L.)) after the
Fukushima Dai-ichi Nuclear Power Plant
accident. J Environ Radioact 152: 119-126(2016).
Hirose, K. Two-years trend of monthly
137
Cs deposition observed in Kanto andsouth Tohoku areas, Japan: effects of the
Fukushima Dai-ichi nuclear power plant
accident. J Radioanal Nucl Chem 303(2):1327-1329 (2015).
Hirose, K. Fukushima Daiichi Nuclear
Plant accident: Atmospheric and oceanic
impacts over the five years. J Environ
Radioact 157: 113-130 (2016).
Hiyama, A., C. Nohara, S. Kinjo et al. The
biological impacts of the Fukushima
nuclear accident on the pale grass blue
butterfly. Sci Rep 2: 570 (2012).
Hiyama, A., W. Taira, M. Iwasaki et al.
Geographical distribution of morphologicalabnormalities and wing color patternmodifications of the pale grass blue
butterfly in northeastern Japan. Entomol
Sci 20(1): 100-110 (2017).
Horiguchi, T., H. Yoshii, S. Mizuno et al.
Decline in intertidal biota after the 2011
Great East Japan Earthquake and Tsunami
and the Fukushima nuclear disaster: fieldobservations. Sci Rep 6: 20416 (2016).
Howard, B.J., S. Fesenko, M. Balonov et al.
A comparison of remediation after the
Chernobyl
andFukushima
Daiichi
accidents. Radiat Prot Dosim 173(1-3):
170-176 (2017).
IAEA. The Fukushima Daiichi accident.
Technical volume 5/5: Post-accident
recovery. International Atomic Energy
Agency. Vienna, 2015.
Igarashi, Y., M. Kajino, Y. Zaizen et al.
Atmospheric radioactivity over Tsukuba,
Japan: a summary of three years ofobservations after the FDNPP accident.
Progress in Earth and Planetary Science2(1): 44 (2015).

I3

I4

I5

I6

I7

I8

J1

K1

K2

K3

K4

Iguchi, K., K. Fujimoto, H. Kaeriyama et al.
Cesium-137 discharge into the freshwater
fishery ground of grazing fish, ayu
Plecoglossus altivelis after the March 2011
Fukushima nuclear accident. Fish Sci
79(6): 983-988 (2013).
Inomata, Y., M. Aoyama, T. Tsubono et al.
Spatial and temporal distributions of(134)Cs and (137)Cs derived from theTEPCO Fukushima Daiichi Nuclear Power
Plant accident in the North Pacific Ocean
by using optimal interpolation analysis.
Environ Sci Process Impacts 18(1):126-136 (2016).
Inoue, M., H. Kofuji, K. Fujimoto et al.
Delivery mechanism of (134)Cs and(137)Cs in seawater off the Sanriku Coast,
Japan, following the Fukushima Dai-ichi
NPP accident. J Environ Radioact 137:
113-118 (2014).
Inoue, M., Y. Shirotani, S. Nagao et al.
Migration of the FDNPP-derived 134Cs and137
Cs along with 226Ra and 228Ra
concentrations across the northwestern
North Pacific Ocean. J Environ Radioact
162-163: 33-38 (2016).
Ishikawa, T., S. Yasumura, K. Ozasa et al.
The Fukushima Health Management
Survey: estimation of external doses toresidents in Fukushima Prefecture. Sci Rep
5: 12712 (2015).
Ishikawa, T., S. Yasumura, A. Ohtsuru et al.
An influential factor for external radiationdose estimation for residents after the
Fukushima Daiichi Nuclear Power Plant
accident-time spent outdoors for residents
in Iitate Village. J Radiol Prot 36(2):255-268 (2016).
Jäckel, B.S., A. Bevilacqua, G. Ducros et al.
Landcontamination
activity
data
interpretation from Fukushima Daiichi
accident. Nucl Eng Des 300: 28-33 (2016).
Kaiser, J.C., R. Meckbach, M. Eidemuller
et al. Integration of a radiation biomarker
into modeling of thyroid carcinogenesis
and post-Chernobyl risk assessment.
Carcinogenesis 37(12): 1152-1160 (2016).
Kaneyasu, N., H. Ohashi, F. Suzuki et al.
Sulfate aerosol as a potential transport
medium of radiocesium from the
Fukushima nuclear accident. Environ Sci
Technol 46(11): 5720-5726 (2012).
Katanoda, K., K. Kamo and S. Tsugane.
Quantification of the increase in thyroid
cancer prevalence in Fukushima after the
nuclear disaster in 2011--a potential
overdiagnosis? Jpn J Clin Oncol 46(3):284-286 (2016).
Katata, G., M. Chino, T. Kobayashi et al.
Detailed source term estimation of theatmospheric release for the Fukushima

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 43

K5

K6

K7

K8

K9

K10

K11

K12

K13

Daiichi Nuclear Power Station accident bycoupling simulations of an atmosphericdispersion model with an improved
deposition scheme and oceanic dispersion
model. Atmos Chem Phys 15(2):1029-1070 (2015).
Kim, E., O. Kurihara, N. Kunishima et al.
Internal thyroid doses to Fukushimaresidents-estimation and issues remaining.
J Radiat Res 57 (Suppl 1): i118-i126(2016).
Kim, E., O. Kurihara, N. Kunishima et al.
Early intake of radiocesium by residents
living near the TEPCO Fukushima Dai-Ichi
nuclear power plant after the accident. Part
1: Internal doses based on whole-bodymeasurements by NIRS. Health Phys
111(5): 451-464 (2016).
Kitamura, A., H. Kurikami, K. Sakuma etal.
Redistribution
andexportofcontaminated sediment within eastern
Fukushima Prefecture due to typhoon
flooding. Earth Surf Process Landforms
41(12): 1708-1726 (2016).
Kobayashi, M., K. Suzuki, S. Miyamoto et
al. Urgent study on the contamination ofradionuclides in milk of dairy cows
following the accident at the Fukushima
Daiichi Nuclear Power Plant in Japan.
Nihon Chikusan Gakkaiho 83(1): 57-64(2012). (Japanese).
Konoplev, A., V. Golosov, G. Laptev et al.
Behaviorof
accidentally
releasedradiocesium in soil-water environment:
Looking at Fukushima from a Chernobyl
perspective. J Environ Radioact 151 (Pt 3):
568-578 (2016).
Konoplev, A.V., V.N. Golosov, V.I.
Yoschenko et al. Vertical distribution ofradiocesium in soils of the area affected by
the Fukushima Dai-ichi nuclear power
plant accident. Eurasian Soil Sci 49(5):570-580 (2016).
Kumamoto, Y., M. Aoyama, Y. Hamajimaetal.
Meridional
distribution of
Fukushima-derived radiocesium in surface
seawater along a trans-Pacific line from the
Arctic to Antarctic Oceans in summer 2012.
J Radioanal Nucl Chem 307(3): 1703-1710(2016).
Kumamoto, Y., M. Aoyama, Y. Hamajima
et al. Fukushima-derived radiocesium in thewestern North Pacific in 2014. J Radioanal
Nucl Chem 311(2): 1209-1217 (2017).
Kunii, Y., Y. Suzuki, T. Shiga et al. Severe
psychological distress of evacuees in
evacuation zone caused by the Fukushima
Daiichi nuclear power plant accident: The
Fukushima Health Management Survey.
PLoS One 11(7): e0158821 (2016).

K14

L1

M1

M2

M3

M4

M5

M6

M7

M8

M9

Kusaba, S., K. Matsuoka, K. Abe et al.
Effect of soil surface management onradiocesium concentrations in apple
orchard and fruit. Hort J 85(1): 30-36 (2016).
Leboulleux, S., R.M. Tuttle, F. Pacini et al.
Papillary thyroid microcarcinoma: time toshift from surgery to active surveillance?
Lancet Diabetes Endocrinol 4(11): 933-942(2016).
MAFF. 2012 livestock statistics. Ministryof Agriculture, Forestry and Fishery, Japan.
[Internet] Available from (http://www.estat.go.jp/SG1/estat/List.do?lid=000001105
713) on 1 January 2017. (Japanese).
MAFF. 2011 livestock statistics. Ministryof Agriculture, Forestry and Fishery, Japan.
[Internet] Available from (http://www.estat.go.jp/SG1/estat/List.do?lid=000001099
430) on 1 January 2017. (Japanese).
Malins, A., H. Kurikami, S. Nakama et al.
Evaluation of ambient dose equivalent rates
influenced by vertical and horizontal
distribution of radioactive cesium in soil in
Fukushima Prefecture. J Environ Radioact
151 (Pt 1): 38-49 (2016).
Manabe, N., T. Takahashi, M. Endo et al.
Effects of “Clean Feeding” management on
livestock products contaminated withradioactive cesium due to the Fukushima
Daiichi Nuclear Power Plant accident.
pp.77-90 in: Agricultural Implications of
the Fukushima Nuclear Accident (T.M.
Nakanishi and K. Tanoi, eds.). Springer,
Tokyo, 2016.
Mikami, S., T. Maeyama, Y. Hoshide et al.
Spatial distributions of radionuclides
deposited onto ground soil around the
Fukushima Dai-ichi Nuclear Power Plant
and their temporal change until December
2012. J Environ Radioact 139: 320-343(2015).
Mishra, S., S.K. Sahoo, P. Bossew et al.
Vertical migration of radio-caesium
derived from the Fukushima Dai-ichi
Nuclear Power Plant accident inundisturbed soils of grassland and forest.
J Geochem Explor 169: 163-186 (2016).
Miyamoto, Y., K. Yasuda and M. Magara.
Size distribution of radioactive particles
collected at Tokai, Japan 6 days after the
nuclear accident. J Environ Radioact 132:
1-7 (2014).
ML. Criteria for approving occupational/
non-occupational diseases related toionizing radiation disease. DirectorGeneral's notice No. 810. Ministry of Labour,
Japan, 8 November 1976. (Japanese).
Møller, A.P., A. Hagiwara, S. Matsui et al.
Abundance of birds in Fukushima as
judged from Chernobyl. Environ Pollut
164: 36-39 (2012).

44

M10

M11

M12

M13

N1

N2

N3

N4

N5

O1

O2

2017 WHITE PAPER

Møller, A.P., I. Nishiumi, H. Suzuki et al.
Differences in effects of radiation onabundance of animals in Fukushima andChernobyl. Ecol Indic 24: 75-81 (2013).
Mukai, H., A. Hirose, S. Motai et al.
Cesium adsorption/desorption behavior ofclay
mineralsconsidering
actualcontamination conditions in Fukushima.
Sci Rep 6: 21543 (2016).
Mukai, H., S. Motai, T. Yaita et al.
Identification of the actual cesiumadsorbing materials in the contaminatedFukushima soil. Appl Clay Sci 121-122:
188-193 (2016).
Muramatsu, Y., H. Matsuzaki, C. Toyama
et al. Analysis of 129I in the soils of
Fukushima
Prefecture:
preliminary
reconstruction of 131I deposition related tothe accident at Fukushima Daiichi Nuclear
Power Plant (FDNPP). J Environ Radioact
139: 344-350 (2015).
Nagao, S., M. Kanamori, S. Ochiai et al.
Migration behavior of 134Cs and 137Cs in
the Niida River water in Fukushima
Prefecture, Japan during 2011–2012.
J Radioanal Nucl Chem 303(2): 1617-1621(2015).
Nagataki, S. Minimizing the health effectsof the nuclear accident in Fukushima on
thyroids. Eur Thyroid J 5(4): 219-223(2016).
Naito, W., M. Uesaka, C. Yamada et al.
Relationship between individual external
doses, ambient dose rates and individuals'
activity-patterns in affected areas in
Fukushima following the Fukushima
Daiichi Nuclear Power Plant accident.
PLoS One 11(8): e0158879 (2016).
Naulier, M., F. Eyrolle-Boyer, P. Boyer et
al. Particulate organic matter in rivers of
Fukushima: An unexpected carrier phasefor radiocesiums. Sci Total Environ 579:
1560-1571 (2017).
Nippon Foundation. Recommendations: theFifth International Expert Symposium inFukushima on Radiation and Health.
[Internet] Available from (http://www.nipponfoundation.or.jp/en/news/articles/2016/img/60/
1.pdf)
Ochiai, S., H. Hasegawa, H. Kakiuchi et al.
Temporal variation of post-accident
atmospheric 137Cs in an evacuated area of
Fukushima Prefecture: Size-dependent
behaviors of 137Cs-bearing particles.
J Environ Radioact 165: 131-139 (2016).
Oe, M., S. Fujii, M. Maeda et al. Threeyear trend survey of psychological distress,
post-traumatic stress, and problem drinking
among residents in the evacuation zone
after the Fukushima Daiichi Nuclear Power
Plant accident [The Fukushima Health

O3

O4

O5

O6

O7

O8

O9

O10

O11

O12

O13

Management Survey]. Psychiatry Clin
Neurosci 70(6): 245-252 (2016).
Ohira, T., M. Hosoya, S. Yasumura et al.
Evacuation and risk of hypertension after
the Great East Japan earthquake: The
Fukushima Health Management Survey.
Hypertension 68(3): 558-564 (2016).
Ohira, T., M. Hosoya, S. Yasumura et al.
Effect of evacuation on body weight after
the Great East Japan earthquake. Am J Prev
Med 50(5): 553-560 (2016).
Ohira, T., H. Takahashi, S. Yasumura et al.
Comparison of childhood thyroid cancer
prevalence among 3 areas based on
external radiation dose after the Fukushima
Daiichi nuclear power plant accident.
Medicine 95(35): e4472 (2016).
Ohmori, H., Y. Sasaki, K. Tajima et al.
Radioactive caesium concentrations in pigs
fed brown rice contaminated by the Tokyo
Electric Power Company Fukushima
Daiichi nuclear power plant. Livestock Sci
159: 156-160 (2014).
Ohmori, Y., M. Kajikawa, S. Nishida et al.
The effect of fertilization on cesium
concentration of rice grown in a paddy
field in Fukushima Prefecture in 2011 and2012. J Plant Res 127(1): 67-71 (2014).
Oinuma, H., K. Yanai, H. Matsuyama et al.
Inhibitory effect of zeolite and bentonite on
absorption radioactive cesium in daily
cattle. Tohoku J Agric Res 65: 89-90(2012). (Japanese).
Oinuma, H., M. Saito, Y. Oda et al. Effectof zeolite supplementation on the transferof radioactive cesium from diet in dairy
cows. Nihon Chikusan Gakkaiho 84(3):333-339 (2013). (Japanese).
Okano, T., H. Ishiniwa, M. Onuma et al.
Effects of environmental radiation on testes
and spermatogenesis in wild large Japanesefield mice (Apodemus speciosus) from
Fukushima. Sci Rep 6: 23601 (2016).
Orita, M., K. Nakashima, N. Hayashida etal. Concentrations of radiocesium in local
foods collected in Kawauchi village after
the accident at the Fukushima Dai-ichi
Nuclear Power Station. Sci Rep 6: 28470(2016).
Otaki, J.M. Fukushima's lessons from theblue butterfly: A risk assessment of thehuman living environment in the postFukushima era. Integr Environ Assess
Manag 12(4): 667-672 (2016).
Oura, Y., M. Ebihara, H. Tsuruta et al. A
databaseofhourlyatmosphericconcentrations of radiocesium (134Cs and
137Cs) in suspended particulate mattercollected in March 2011 at 99 air pollution
monitoring stations in eastern Japan. J Nucl
Radiochem Sci 15(2): 1-12 (2015).

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 45

P1

Q1

S1

S2

S3

S4

S5

S6

S7

S8

Park, S., C.M. Oh, H. Cho et al.
Association between screening and thethyroid cancer "epidemic" in South Korea:
evidence from a nationwide study. Br Med
J 355: i5745 (2016).
Qiu, X., S.L. Undap, M. Honda et al.
Pollution of radiocesium and radiosilver inwharf roach (Ligia sp.) by the Fukushima
Dai-ichi Nuclear Power Plant accident.
J Radioanal Nucl Chem 311(1): 121-126(2016).
Sakaguchi, A., P. Steier, Y. Takahashi et al.
Isotopic compositions of (236)U and Pu
isotopes in "black substances" collectedfrom roadsides in Fukushima prefecture:
fallout from the Fukushima Dai-ichi
nuclear power plant accident. Environ Sci
Technol 48(7): 3691-3697 (2014).
Sakai, A., T. Ohira, M. Hosoya et al. White
blood cell, neutrophil, and lymphocyte
counts in individuals in the evacuation zone
designated by the government after the
Fukushima Daiichi Nuclear Power Plant
accident:the
Fukushima
HealthManagement Survey. J Epidemiol 25(1):80-87 (2015).
Sakumi, A., R. Miyagawa, Y. Tamari et al.
External effective radiation dose to workers
in the restricted area of the Fukushima
Daiichi Nuclear Power Plant during thethird year after the Great East Japan
Earthquake. J Radiat Res 57(2): 178-181(2016).
Salbu, B. and O.C. Lind. Radioactive
particles released to the environment fromthe Fukushima reactors-Confirmation isstill needed. Integr Environ Assess Manag
12(4): 687-689 (2016).
Sasaki, Y., H. Abe, K. Mitachi et al. The
transfer of radiocesium from the bark to thestemflow of chestnut trees (Castanea
crenata) contaminated by radionuclides
from the Fukushima Dai-ichi nuclear
power plant accident. J Environ Radioact
161: 58-65 (2016).
Sato, I., M. Natsuhori, J. Sasaki et al. Local
variation of soil contamination withradioactive cesium at a farm in Fukushima.
Jpn J Vet Res 64(1): 95-99 (2016).
Satou, Y., K. Sueki, K. Sasa et al. First
successful isolation of radioactive particles
from soil near the Fukushima Daiichi
Nuclear Power Plant. Anthropocene 14:
71-76 (2016).
Scherb, H.H., K. Mori and K. Hayashi.
Increases in perinatal mortality inprefectures contaminated by the Fukushima
nuclear power plant accident in Japan: A
spatially stratified longitudinal study.
Medicine (Baltimore) 95(38): e4958 (2016).

S9

S10

S11

S12

S13

S14

S15

T1

T2

T3

SCJ. A review of the model comparison oftransportation and deposition of radioactive
materials released to the environment as aresult of the Tokyo Electric Power
Company’s Fukushima Daiichi Nuclear
Power Plant accident. Sectional Committee
on Nuclear Accident, Science Council ofJapan, Tokyo, 2014.
Snow, M.S., D.C. Snyder and J.E. Delmore.
Fukushima Daiichi reactor source term
attribution using cesium isotope ratios fromcontaminated environmental samples.
Rapid Commun Mass Spectrom 30(4):523-532 (2016).
Steinhauser, G., T. Niisoe, K.H. Harada etal. Post-accident sporadic releases ofairborne radionuclides from the Fukushima
Daiichi Nuclear Power Plant site. Environ
Sci Technol 49(24): 14028-14035 (2015).
Sugiura, Y., M. Shibata, Y. Ogata et al.
Evaluation of radiocesium concentrations
in new leaves of wild plants two years after
the Fukushima Dai-ichi Nuclear Power
Plant accident. J Environ Radioact 160:
8-24 (2016).
Sunaga, Y. and H. Harada. Simple method
for estimating soil mass loading onto plantsurface using magnetic material content asa soil indicator - Influence of soil adhesion
to vegetation on radioactive cesium
concentration in forage. J Environ Radioact
164: 125-132 (2016).
Suzuki, S. Childhood and adolescent
thyroid cancer in Fukushima after the
Fukushima Daiichi Nuclear Power Plant
accident: 5 years on. Clin Oncol (R Coll
Radiol) 28(4): 263-271 (2016).
Suzuki, S., S. Suzuki, T. Fukushima et al.
Comprehensive survey results of childhood
thyroid ultrasound examinations inFukushima in the first four years after the
Fukushima Daiichi Nuclear Power Plant
accident. Thyroid 26(6): 843-851 (2016).
Tagami, K., B.J. Howard and S. Uchida.
The time-dependent transfer factor ofradiocesium from soil to game animals inJapan after the Fukushima Dai-ichi nuclear
accident. Environ Sci Technol 50(17):9424-9431 (2016).
Tagami, K. and S. Uchida. Considerationon the long ecological half-life component
137
Cs in demersal fish based on fieldofobservation results obtained after the
Fukushima accident. Environ Sci Technol
50(4): 1804-1811 (2016).
Takada, M., T. Yamada, T. Takahara et al.
Spatial variation in the (137)Cs inventory
in soils in a mixed deciduous forest in
Fukushima, Japan. J Environ Radioact 161:
35-41 (2016).

46

T4

T5

T6

T7

T8

T9

T10

T11

T12

U1

2017 WHITE PAPER

Tanaka, S., K. Hatakeyama, S. Takahashi
et al. Radioactive contamination ofarthropods from different trophic levels inhilly and mountainous areas after the
Fukushima Daiichi nuclear power plant
accident. J Environ Radioact 164: 104-112(2016).
Tani, K., O. Kurihara, E. Kim et al.
Implementation of iodine biokinetic model
for interpreting I-131 contamination inbreast milk after the Fukushima nuclear
disaster. Sci Rep 5: 12426 (2015).
Tateda, Y., D. Tsumune, T. Tsubono et al.
Status of (137)Cs contamination in marine
biota along the Pacific coast of easternJapan derived from a dynamic biologicalmodel two years simulation following the
Fukushima accident. J Environ Radioact
151 (Pt 2): 495-501 (2016).
Terada, H., G. Katata, M. Chino et al.
Atmospheric discharge and dispersion ofradionuclides during the Fukushima Daiichi Nuclear Power Plant accident. Part II:
verification of the source term and analysisof regional-scale atmospheric dispersion.
J Environ Radioact 112: 141-154 (2012).
Terasaka, Y., H. Yamazawa, J. Hirouchi etal. Air concentration estimation ofradionuclides discharged from Fukushima
Daiichi Nuclear Power Station using
NaI(Tl) detector pulse height distribution
measured in Ibaraki Prefecture. J Nucl Sci
Technol 53(12): 1919-1932 (2016).
Tokonami, S., M. Hosoda, S. Akiba et al.
Thyroid doses for evacuees from the
Fukushima nuclear accident. Sci Rep 2:507 (2012).
Tsubono, T., K. Misumi, D. Tsumune et al.
Evaluation of radioactive cesium impact
from atmospheric deposition and direct
release fluxes into the North Pacific fromthe Fukushima Daiichi nuclear power plant.
Deep-Sea Res Part I Oceanogr Res Pap
115: 10-21 (2016).
Tsukada, H. and K. Ohse. Concentration ofradiocaesium in rice and irrigation water,and soil management practices in Oguni,Date, Fukushima. Integr Environ Assess
Manag 12(4): 659-661 (2016).
Tsuruta, H., Y. Oura, M. Ebihara et al. First
retrievalofhourlyatmosphericradionuclides just after the Fukushima
accident by analyzing filter-tapes ofoperational air pollution monitoring
stations. Sci Rep 4: 6717 (2014).
Uematsu, S., H. Vandenhove, L. Sweeck et
al. Variability of the soil-to-plantradiocaesium transfer factor for Japanesesoils predicted with soil and plant
properties. J Environ Radioact 153: 51-60(2016).

U2

U3

U4

U5

V1

V2

V3

W1

W2

UNSCEAR. Sources, Effects and Risks of
Ionizing Radiation. Volume I: Report to theGeneral Assembly and Scientific Annex A.
UNSCEAR 2013 Report. United Nations
Scientific Committee on the Effects ofAtomic Radiation. United Nations sales
publication E.14.IX.1. United Nations, New
York, 2014.
UNSCEAR. Sources, Effects and Risks of
Ionizing Radiation. Report to the General
Assembly and Scientific Annexes A and B.
UNSCEAR 2012 Report. United Nations
Scientific Committee on the Effects ofAtomic Radiation. United Nations sales
publication E.16.IX.1. United Nations, New
York, 2015.
UNSCEAR. Developments since the 2013
UNSCEAR Report on the Levels andEffects of Radiation Exposure due to the
Nuclear Accident following the Great EastJapan Earthquake and Tsunami. A 2015
white paper to guide the ScientificCommittee's future programme of work.
United Nations Scientific Committee on
the Effects of Atomic Radiation. United
Nations, New York, 2015.
UNSCEAR. Developments since the 2013
UNSCEAR Report on the Levels andEffects of Radiation Exposure due to the
Nuclear Accident following the Great EastJapan Earthquake and Tsunami. A 2016
white paper to guide the ScientificCommittee's future programme of work.
United Nations Scientific Committee on
the Effects of Atomic Radiation. United
Nations, New York, 2016.
Vaccarella, S., S. Franceschi, F. Bray et al.
Worldwide thyroid-cancer epidemic? The
increasing impact of overdiagnosis. N Engl
J Med 375(7): 614-617 (2016).
Vives i Batlle, J. Dynamic modelling ofradionuclide uptake by marine biota:
application to the Fukushima nuclear
power plant accident. J Environ Radioact
151 (Pt 2): 502-511 (2016).
Vives i Batlle, J., N.A. Beresford, K.
Beaugelin-Seiller et al. Inter-comparison of
dynamic models for radionuclide transfer
to marine biota in a Fukushima accident
scenario. J Environ Radioact 153: 31-50 (2016).
Wada, T., T. Fujita, Y. Nemoto et al.
Effects of the nuclear disaster on marine
products in Fukushima: An update after
five years. J Environ Radioact 164: 312324 (2016).
Wada, T., A. Tomiya, M. Enomoto et al.
Radiological impact of the nuclear power
plant accident on freshwater fish in
Fukushima: An overview of monitoring
results. J Environ Radioact 151 (Pt 1):
144-155 (2016).

DEVELOPMENTS SINCE THE 2013 UNSCEAR REPORT [...] 47

W3

W4

W5
W6

Y1

Y2

Y3

Y4

Wakabayashi, S., S. Itoh, N. Kihou et al.
Influence of water management andfertilizer application on (137)Cs and(133)Cs uptake in paddy rice fields.
J Environ Radioact 157: 102-112 (2016).
Watanabe, Y., S. Ichikawa, M. Kubota et al.
Morphological defects in native Japanese
fir trees around the Fukushima Daiichi
Nuclear Power Plant. Sci Rep 5: 13232(2015).
Williams, D. Thyroid growth and cancer.
Eur Thyroid J 4(3): 164-173 (2015).
Win, K.T., A.Z. Oo, K. Kojima et al.
Genotypic
differencein(137)Cs
accumulation and transfer from thecontaminated field in Fukushima to azuki
bean (Vigna angularis). J Environ Radioact
158-159: 138-147 (2016).
Yamaguchi, N., M. Mitome, A.H. Kotone
et al. Internal structure of cesium-bearing
radioactive microparticles released from
Fukushima nuclear power plant. Sci Rep 6:20548 (2016).
Yamaguchi, N., I. Taniyama, T. Kimura etal. Contamination of agricultural products
and soils with radiocesium derived fromthe accident at TEPCO Fukushima Daiichi
Nuclear Power Station: monitoring, casestudies and countermeasures. Soil Sci Plant
Nutr 62(3): 303-314 (2016).
Yamamoto, S., K. Mutou, H. Nakamura etal.
Assessmentofradiocaesium
accumulation by hatchery-reared salmonids
after the Fukushima nuclear accident. Can J
Fish Aquat Sci 71(12): 1772-1775 (2014).
Yamashita, S. and G. Thomas. Thyroid
Cancer and Nuclear Accidents: Long-Term
Aftereffects of Chernobyl and Fukushima.
Academic Press, 2017.

Y5

Y6

Y7

Y8

Y9

Y10

Z1

Yang, B., Y. Onda, Y. Wakiyama et al.
Temporal changes of radiocesium in
irrigated paddy fields and its accumulationin rice plants in Fukushima. Environ Pollut
208(Pt B): 562-570 (2016).
Yasui, S. Establishment of the central
radiation dose registration system fordecontamination
work
involving
radioactive fallout emitted by the
Fukushima Daiichi APP accident. J Occup
Environ Hyg 13(10): D166-D174 (2016).
Yasui, S. A recommended epidemiologicalstudy design for examining the adverse
health effects among emergency workers
who experienced the TEPCO Fukushima
Daiichi NPP accident in 2011. J Occup
Environ Hyg 13(5): D77-D88 (2016).
Yasumura, S. Evacuation effect on excess
mortality among institutionalized elderly
after the Fukushima Daiichi nuclear power
plant accident. Fukushima J Med Sci 60(2):192-195 (2014).
Yoschenko, V., K. Nanba, S. Yoshida et al.
Morphological abnormalities in Japanese
red pine (Pinus densiflora) at the territories
contaminated as a result of the accident at
Fukushima Dai-Ichi Nuclear Power Plant.
J Environ Radioact 165: 60-67 (2016).
Yumimoto, K., Y. Morino, T. Ohara et al.
Inverse modeling of the 137Cs source termof the Fukushima Dai-ichi Nuclear Power
Plant accident constrained by a deposition
map monitored by aircraft. J Environ
Radioact 164: 1-12 (2016).
Zablotska, L.B., E.A. Nadyrov, A.V.
Rozhko et al. Analysis of thyroid malignant
pathologic findings identified during
3 rounds of screening (1997-2008) of acohort of children and adolescents from
Belarus exposed to radioiodines after the
Chernobyl accident. Cancer 121(3):457-466 (2015).

unscear.org

In 1955 the United Nations General Assembly established the Scientific Committee on
the Effects of Atomic Radiation (UNSCEAR) in response to concerns about the effectsof ionizing radiation on human health and the environment. At that time fallout fromatmospheric nuclear weapons tests was reaching people through air, water and food.
UNSCEAR was to collect and evaluate information on the levels and effects of ionizing
radiation. Its first reports laid the scientific grounds on which the Partial Test Ban Treaty
prohibiting atmospheric nuclear weapons testing was negotiated in 1963.

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Over the decades, UNSCEAR has evolved to become the world authority on the global
level and effects of atomic radiation. UNSCEAR’s independent and objective evaluationof the science are to provide for—but not address—informed policymaking and decisionmaking related to radiation risks and protection.