Industrial Disease Clinical Research Grants fromJapanese Ministry of Health, Labour and Welfare

Epidemiological Study on the Health Effects in Radiation
Workers(Epidemiological Study of Health Effects in TEPCO Fukushima Daiichi Nuclear Emergency Workers)

The first period (FY2014 to FY2018)

Third Party Committee Report

Chairman

Ginji Endo

June 2020−21−

Table of contents
Introduction ................................................................................................................................. 1
Third-party committee report
Chapter I

Evaluation of research so far ............................................................................... 3

1. Securing research participants ............................................................................................... 3
2. Scientific evaluation of health effects by radiation exposure under emergency work .......... 3(1) Statistical detection power and analysis method ............................................................. 3(2) Evaluation of radiation dose .......................................................................................... 4(3) Survey of cause of death and cancer morbidity ............................................................... 4(4) Survey of thyroid cancer morbidity ............................................................................... 5(5) Survey of cataract .......................................................................................................... 6(6) Survey of psychological influence .................................................................................. 7(7) Research on radiation biology ....................................................................................... 7
3. Research system .................................................................................................................. 8
Chapter II

Proposal to research in the second period ...................................................... 12

1. Securing research participants ........................................................................................... 12
2. Scientific evaluation of health effects of radiation exposure under emergency work ....... 13(1) Statistical detection power and analysis method ......................................................... 14(2) Confounding factors .................................................................................................... 14(3) Dose evaluation ........................................................................................................... 15(4) Survey of cause of death and cancer morbidity ........................................................... 16(5) Survey of thyroid cancer morbidity ............................................................................. 17(6) Survey of cataract ........................................................................................................ 19(7) Survey of psychological influence .............................................................................. 20
3. Research system ................................................................................................................ 21
Chapter III

Summary ............................................................................................................ 21−22−

Introduction
This research started as clinical research for industrial accident diseases by the Ministry of Health,Labour and Welfare in FY2014, four years after the accident at TEPCO’s Fukushima Daiichi Nuclear
Power Plant. Prior to starting the research, experts were gathered around the Industrial Safety and Health
Department Manager of the Labor Standards Bureau in the Ministry of Health, Labour and Welfare in
February 2014, a “Review meeting by experts concerning the ideal state of epidemiologic study for
emergency workers at TEPCO’s Fukushima Daiichi Nuclear Power Plant” (hereafter referred to as “Ideal
state review meeting”) was established, and conferences were thereafter held five times. In this review
meeting, the research method for epidemiologically investigating the health effects on emergency workers
due to radiation exposure, etc. were reviewed, and the report showing the basic items regarding the way
to proceed with this research was prepared and published based on this.
The study plan of this research was developed following the basic policy of that report, and the research
was started in October 2014. The progress status of the research was checked to reveal that some parts
progressed according to the policy, while other parts did not. In addition, during this period, the technicaladvances and the modification of social needs were remarkable, and the necessity of a review of the basic
policy became clear.
Concerning how to proceed with this research that is expected to take a long period of time, the reportof the review meeting proposed to “establish an independent committee (third-party committee) including
researchers whose research achievements are internationally evaluated” “at intervals of once every five
years in addition to the usual research evaluation, in order to secure good quality research” and “toimplement the evaluation of whether any arbitrary deviation exists that may derive analysis results thatare statistically significant or statistically insignificant concerning the selection of the adopted study
hypothesis, study plan, exposure factor, statistical technique, etc.”
Since five years of the first period has elapsed this time, it was decided to establish this committee as
an important place where third party experts not only evaluate the study achievements, but also propose
the method for proceeding with the research of the next period based on that. In order to select committee
members, we explained to the relevant expert societies about the aim of the committee establishment,
asked to recommend committee members and held a third-party committee with the following
composition of members:Name list of the third-party committee
Hirotsugu Ueshima

Specially appointed professor, Center for Epidemiologic Research in
Asia, Shiga University of Medical Science

Ginji Endo*

Director, Osaka Labor Health General Center, Japan Industrial Safety
and Health Association
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Kazuyuki Omae

Professor Emeritus, Keio University

Michiaki Kai

Professor, School of Nursing, Oita University of Nursing and Health
Sciences

Takashi Kitaoka

Professor, Ophthalmology and Visual Science, Nagasaki University
Graduate School of Biomedical Sciences

Kazuo Sakai

Professor, Higashigaoka and Tachikawa Nursing School, Tokyo
Healthcare University

Gen Suzuki

Director, International University of Health and Welfare

Masayuki Tatemichi**Professor, Dept of Preventive Medicine, Tokai University School of
Medicine

Akizumi Tsutsumi*: Chairman

Professor, Public Health, School of Medicine, Kitasato University**: Vice-chairman

Date and time when Third-party Committee is to be held
1st meeting

10 am to 4 pm, November 5, 2019, Room No. 702, 7th floor, Vision Center in front ofTokyo Station
2nd meeting

1 pm to 3 pm, January 28, 2020, Room No. 701, 7th floor, Vision Center in front ofTokyo Station
3rd meeting

June 26, 2020

To be held using documentation**Although the third meeting of the committee was planned to be held on March 23, 2020, the meeting
was suspended due to the self-restraint request, etc. associated with the novel coronavirus infection, andit was decided to hold the committee using documentation.
The deliberation of the committee was implemented on the committee’s own initiative under themutually elected chairman, and this report was prepared.
We described the details of the establishment of this committee and sincerely thank Director Endo, who
acted as the chairman of the third-party committee to establish this committee and prepare the report,
along with every committee member, and the parties concerned of Ministry of Health, Labour and Welfare
for their great efforts.
On June 26, 2020
Epidemiologic study for emergency workers at TEPCO’s Fukushima Daiichi Nuclear Power Plant(Public invitation name: Epidemiologic study concerning health effects on radiation workers)
Study representative Toshiteru Okubo
2
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Third-party committee report
Chapter I

Evaluation of research so far

This chapter summarizes the evaluation, etc. of research achievements in the first period from the aspectof securing research participants, scientific evaluation of health effect by radiation exposure underemergency work and research system.
1. Securing research participants
In the difficult circumstances whereby survey subjects (19,808) who were emergency workers are
dispersed nationwide, and that three or more years have elapsed before the start of survey since thenuclear power plant accident and the end of the subsequent emergency work, the survey was planned,
informed consent was obtained, and invitations to the subjects to participate in the health survey were
implemented. Although the number of persons who agreed to take the follow-up survey as a cohort
survey against the population is currently 7,270, a long time had elapsed before the start of the survey
and the locations of subjects were dispersed all over the prefectures. Therefore, considering the difficultyof follow-up of persons who do not belong to the limited region or workplace, it can be well evaluatedthat suitable invitation to each subject to participate in the research and the following health survey weresuccessfully implemented. Since the participation ratio (36.7% of subjects) with the total number as adenominator is not necessarily high, it is difficult to deny that a sufficient number of participants forclarifying the risk to emergency workers was not secured. However, it is possible to clarify certain healtheffects due to high dose exposure because the participation ratios for each exposure dose are as high as
79.9% and 78.4% for the population of 100 mSv or more to less than 150 mSv and the population of
150 mSv or more, respectively. In addition, since minute surveys such as a cataract survey and thyroid
echo survey were implemented, it can be said this is a valuable research not seen in a conventional
exposure survey.
2. Scientific evaluation of health effects by radiation exposure under emergency work
(1) Statistical detection power and analysis method
When applying the evaluation index (end point) to probabilistic events such as cancer, the numberof subjects was small in the result so far, and analysis is obliged to be performed with insufficient
detection power. As the method for accepting the limitation of insufficient detection power, aregression analysis is planned that takes the event capable of being observed as a response variable,with the exposure dose as an explanatory variable. At least, the risk factor for the outbreak ofcirculatory disease is possible to analyze because it was surveyed in this cohort. However, although
the outbreak factor of circulatory diseases is strongly related to lifestyle habits and the adjustment of
a confounding factor is required, it can be well evaluated that the information on the confounding
factor has been collected.
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(2) Evaluation of radiation dose
Since the quality of dose evaluation for emergency workers is important because the reasonablenessof the epidemiologic survey is affected by this quality, this study performs a detailed examinationfrom both the physical and biological aspects of dose evaluation. In the evaluation of the thyroid
absorbed dose received by internal exposure through the inhalation of radioactive iodine (mainly I131) with a large dose contribution, it was recognized that the accuracy of thyroid measurement
performed at the time of the accident is sufficiently high even when considering the uncertainty of theposition of an examinee, and it was clarified that the volume of thyroid shape obtained from the MRI
images shows large personal difference.
Further, the evaluation of the uncertainty regarding the estimated dose, including the effect by acuteingestion of radioactive iodine, the effect of chronic ingestion and the effect on in-body behavior ofradioactive iodine due to the ingestion of a stable iodine tablet remains as future tasks. On the other
hand, the analysis of iodine 129 in urine sampled for evaluating internal exposure over several months
just after the accident is performed using the accelerator mass spectrometry method (AMS). This
result will hereafter be the important information for correcting the inhalation ingestion pattern andthe personal difference of in-body behavior that will be the uncertainty in the dose estimated from thethyroid measurement.
Concerning external exposure, the dose information of personal dosimeters was further obtained
from the central registration center of the Radiation Effects Association based on personal agreement.
The evaluation of the reading of a dosimeter and the conversion factor to the organ absorption dose
and the verification of the reasonableness of the estimated value of a dosimeter by the chromosome
aberration analysis have been advanced, and the total work of dose evaluation progresses steadily.
From the above points, the point of this research to be most highly evaluated is that the dosimetryis accurately identified. In addition, the number of workers whose dosimetry during emergency work
exceeds 100 mSv is 174, and we consider that this is important data enabling the evaluation ofcomplex health effects concerning the exposure to 100 mSv or more by hereafter adding medical
exposure.
(3) Survey of cause of death and cancer morbidity
The cause of death and cancer morbidity survey subcommittee has the purpose of grasping thecause of death and cancer morbidity. Since matters concerning the cause of death and cancer morbidity
above all are major consequences, a high degree of attention is paid, and a high grasp rate and longterm follow-up are required. As the follow-up plan, information on the cause of death is periodicallyunderstood by obtaining death slips through the procedure of the out-of-purpose utilization of thedemographic surveys concerning subjects whose agreement has been obtained. Further, since it is
4
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difficult to obtain consent that was not anticipated at the beginning, we decided to deal with it by optout, and take the technique for reviewing the content of opt-out for subjects who continue medical
checkups. The periodical application of death slips for the demographic survey of the generation
corresponding to the follow-up subjects is planned in order to calculate the standardized death ratio,
and the information on the death slips for the demographic survey from March 2011 to December
2016 is already issued.
Concerning cancer morbidity, since grasping the morbidity in periodic cancer tests, the periodic
cancer registration in the prefectural regions where the subjects live and nationwide cancer registration
were both fully realized, it is planned to submit the list of survey subjects to the National Cancer
Center to collect the information from the nationwide cancer registration. Concerning the research,
the acquisition of agreement was implemented on a highest priority basis as the activity in the first
period, and a lot of labor was spent from the viewpoint that agreement is required in order to use theinformation on the cancer registration for this research. We have evaluated that the above matter isreasonable as the methodology for the follow-up in the follow-up environment at the beginning of theplan.
(4) Survey of thyroid cancer morbidity
The thyroid cancer survey subcommittee has the purpose of collecting and analyzing 1) the data of
627 subjects who were subjected to thyroid tests among 1,972 subjects of the exposure population of
the thyroid equivalent dose of more than 100 mSv during emergency work who are survey subjectsof the team research (Sobue team) that was implemented in the special research project of the Healthand Labor Sciences Research Grant in FY 2013, 2) the dose evaluation which has been implemented
for the control population of 1437 of said dose of 100 mSv or less and 3) the data of thyroid ultrasonictests (data of the old research team) as task 1, and also to examine the method for implementing
thyroid tests for the total number of subjects of about 20,000 emergency workers and to collect andanalyze the test results as task 2.
It can be well evaluated that acquiring agreement for using the thyroid test data of the old researchsubjects and the thyroid test data possessed by TEPCO for “Epidemiologic study for TEPCO
Fukushima Daiichi Nuclear Power Plant emergency workers” (Nuclear Emergency Workers Study;
NEWS Study) was promoted, and that the agreement from 577 old study subjects and 1,531 TEPCO
employees as of January 2019 had been obtained, resulting in the increase of the number of subjects
in task 1. Task 2 has decided the policy whereby thyroid tests are conducted for all the subjects, inaddition to all the subjects (1,972) exposed to a thyroid equivalent dose of 100 mSv or more among
about 20,000 subjects.
Concerning the accuracy control of the thyroid test, the lecture classes for increasing certified
bodies and certified engineers for conducting the thyroid ultrasonic test are being conducted, and 123
5
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certified engineers and 60 certified facilities have been recognized as of the end of December 2018.
An accuracy control committee was established in Jichi Medical University, and a thyroid ultrasonictest information system that enables the examination of image data and findings by the accuracy
control committee has already been established. In addition, 130 facilities acting as bodies for
conducting a secondary test for subjects who required one based on the findings in the thyroid test
have been secured nationwide. Further, it can be judged that the system for conducting the test fromthe aspect of research ethics, showing the way of thinking about the judgment result for the writtenconsent explanatory statement was completed.
(5) Survey of cataract
Although the crystalline lens is a tissue sensitive to radiation, the specific evaluation of its effect isdifficult because of the presence of some problems. Firstly, although damage to the crystalline lensresults in its opacity, usually only alteration by aging results in opacity, and other than aging, theeffects of steroid hormones, diabetes, degenerative myopia, etc. sometimes also result in opacity.
Therefore, it is difficult to investigate by distinguishing between the effects of aging alteration, steroid
hormones, diabetes, degenerative myopia, etc. and the hazard from radiation. Secondly, thequantitative evaluation of crystalline lens opacity and vacuolar degeneration is difficult. This researchis meaningful because it intends to establish a new evaluation method and to compare the effects ofaging with those of radiation on cataracts in order to conquer this difficulty.
Firstly, the tests are conducted using an anterior ocular segment analysis and photographingapparatus EAS-1000 capable of evaluating the degree of cataract with the most detail, targeting
TEPCO employees exposed to a dose of 50 mSv or more. In addition to this, a simplified
transillumination camera that is simple to use and enables easy evaluation has been developed by astudy group, and the common usage of this with EAS-1000 is expected to enable coping with studies
that can be implemented in many facilities in the future.
Although the disease type of crystalline lens opacity is classified in various ways, six disease types
are selected this time. These six types are cortex lens opacity (COR), nuclear sclerosis and opacity(NUC), posterior subcapsular opacity (cataract) (PSC), vacuolation in crystalline lens (Vacuoles),retrodot and water cleft (WC). The report this time especially describes the Vacuoles that is thealteration emerging at a comparatively early stage among the six disease types. It shows that eachdisease type (especially distinguished from posterior subcapsular in Vacuoles) tended to increase from2014 to 2016. Also concerning this, the judgment whether this is an actual increase or an apparent
increase is important.
Secondly, a simplified transillumination camera was introduced in 2016 in addition to the initiallyused EAS-1000, assuming it would be used in the NEWS study. Therefore, the introduction of thesimplified transillumination camera in addition to EAS-1000, the standard for the current cataract
6
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study, raises the detection ratio. On the other hand, the apparent increase of the prevalence rate ofcataracts is pointed out as a problem. Further, although the “prevalence rate of cataracts” is described,
the definition of cataract is not determined, hence the definition in this study should be clarified.
Concerning this point, it is necessary to consider it by dividing in between “cataract” and “alterationof the crystalline lens.” Since it is unclear in which position the setting of focus of the simplified
transillumination camera between the anterior and the posterior of crystalline lens enables theidentification of findings about Vacuoles, a check of the depth of field and reproducibility of thisinspection equipment is required.
(6) Survey of psychological influence
The purpose of the psychological influence survey is to follow-up on mental health over the longterm, and the psychological influence is evaluated by questionnaire and composite interviews. Stigma
is also a big theme.
Questionnaires were sent to 4,979 persons, and of those 3,784 were analyzed. Training on the WHO
World Mental Health Composite International Diagnostic Interview (WMH-CIDI) was conducted for
235 survey executors (public health nurses, etc.). As a result of the CIDI, analyzable data wereobtained from 2,130 persons.
In the follow-up on mental health, a wide array of survey items consisting of1) sevierity ofdepression, anxiety disorder, sleep disorder, alcohol ingestion disorder, or serious

PTSD (post-traumatic stress disorders), and 2) existence of stigma, life event, social assistance, sense of coherence,
self-esteem, and self-efficacy were examined, and the analysis of the entry period, the number ofworking days and work breakdown was made possible. In the questionnaire survey, the relationships
between the frequency of depression and action (alcohol ingestion disorder) and the relevant factors
were analyzed by comparing with the survey results, etc. targeting the general population. The stigma
scale for Fukushima Daiichi Nuclear Power Plant emergency workers was developed, and the stigma
after the nuclear disaster and its relevant factors were examined.
It is well evaluated that in spite of the difficulty of surveying, many valuable data were collectedby the composite interviews conducted by survey executors who had received training.
(7) Research of radiation biology
A radiation biology research working group performed the search for a biomarker that is expected
to be utilized in this research in the tests related to radiation adaptive response and thymic lymphomadeveloped model mouse for the purpose of searching for a biomarker for low dose radiation effects,
in order to investigate the relationship between low dose radiation exposure and long term healtheffects. Further, in the test related to human urinary oxidative stress, a field survey was performed incooperation with a medical institution in Fukushima. The result of the survey of human urinary 87
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OHdG in a specified period for persons who received medical examinations showed a slightly higher
value in comparison with a general healthy group, but it cannot be said to be a significant difference.
Although the outcome obtained by five years of research can be evaluated to a certain degree, theselection of the biomarker adaptive to the subjects in this research was not achieved. The researchteam reported that the biological radiation research has been suspended until the time when abiomarker capable of being utilized in this research can be selected, and we consider this to bereasonable. Currently, biomarkers using metabolomics technology are being energetically studied invarious fields with the progress of technology. However, whether the study can be applied to theradiation effects is in the examination stage, and it is necessary to continuously examine the adoptionof a new biomarker considering knowledge both inside and outside the research team.
3. Research system
In the first period, the Radiation Effects Research Foundation acts as a research supervision institute,and eleven institutes nationwide participated in the research. Six research groups in charge of clinicalsurvey, exposure dose evaluation, cause of death and cancer morbidity survey, thyroid cancer survey,
cataract survey, psychological influence survey and radiation biological research were established toproceed with the survey of the health effects due to radiation exposure during emergency work.
Toshiteru Okubo Radiation

Effects

Consulting

Principal

FY 2014

Research

Foundation

Researcher

Investigator

present

ExecutiveDose

FY 2014

Officerevaluation

present

Department

Clinical

FY 2014

Directorsurveypresent

to(RERF)
Makoto Akashi

National

InstitutesforQuantum and Radiologicalto

Science and Technology(QST), National Researchand Development Agency
Waka Oishi

Hiroshima

ClinicalResearch

Department,

Radiation

Effects

Research

Foundation(RERF), Public Interest
Incorporated Foundation

8
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−30−

to

Ryuji Okazaki

Kotaro Ozasa

Fumiyoshi
Kasagi

HiroakiKatayama

Kazuaki Kawai

HirokoKitamura

Eunjoo Kim

DepartmentofRadiological
HealthScience,
InstituteofIndustrial
Ecological
Sciences, University ofOccupational
andEnvironmental
Health(UOEH)
Hiroshima Department of
Epidemiology, Radiation
Effects
Research
Foundation(RERF),
PublicInterest
Incorporated Foundation(Retired)Institute ofRadiation Epidemiology,
Radiation
Effects
Association (REA), Public
Interest
Incorporated
Foundation(Retired) Department ofInformation Technology,
Radiation
Effects
Research
Foundation(RERF), Public Interest
Incorporated Foundation
DepartmentofEnvironmental Oncology,
Institute of Industrial
Ecological
Sciences,
UniversityofOccupational
andEnvironmental
Health(UOEH)
Hiroshima
ClinicalResearch
Department,
Radiation
Effects
Research
Foundation(RERF), Public Interest
Incorporated Foundation
Department of Radiation
Measurement and Dose
Assessment,
National
Institute of Radiological
Sciences (NIRS), National
Institutes for Quantum andRadiological Science andTechnology(QST),
National Research andDevelopment Agency

Professor

BiologicalsurveyFY 2014

topresent

toDirector

Cause of death FY 2014
and cancer
present
morbidity

Institute
DirectorDoseevaluation

FY 20142017

toDepartment
Director

Cause of death FY 2014
and cancer
2017
morbiditytoProfessor

Biological

FY 2017tosurveypresent

DeputyClinical

FY 2017

Office Headsurveypresent

Researcher

Dose

FY 2018

evaluation

present

Department

9
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−31−

to

to

Osamu Kurihara Department of Radiation
Measurement and Dose
Assessment,
National
Institute of Radiological
Sciences (NIRS), National
Institutes for Quantum andRadiological Science andTechnology(QST),
National Research andDevelopment Agency
Radiation
Effects
Kazunori
Research
Foundation
Kodama(RERF), Public Interest
Incorporated FoundationofHiroshi Sasaki Department
Ophthalmology, Special
Research
Division/
DivisionofVisionResearchforEnvironmental
Health,Kanazawa
Medical
University
Jun Shigemura Department of Psychiatry,
Department of Medicine,
FacultyofMedical
Education,
National
Defense Medical College
Department of Radiation
Yumiko Suto
Measurement and Dose
Assessment,
National
Institute of Radiological
Sciences (NIRS), National
Institutes for Quantum andRadiological Science andTechnology(QST),
National Research andDevelopment Agency
Tomotaka Sobue Environmental Medicine
and Population Sciences,
Department of Social
Medicine,
Graduate
School of Medicine, Osaka
University
Department of Radiation
Kotaro Tani
Measurement and Dose
Assessment,
National
Institute of Radiological
Sciences (NIRS), National
Institutes for Quantum andRadiological Science andTechnology(QST),
National Research andDevelopment Agency

Department

Dose

FY 2014

Directorevaluation

present

Principal

International

FY 2014

Researcher

matter2017

Professor

Cataract

FY 2014surveypresent

Associate

Psychological

FY 2015

Professor

effects survey

present

Team Leader Dose

Professor

Researcher

10（ 10 ）−32−

FY 2014

evaluation

present

Thyroid

FY 2014cancer survey

present

Dose

FY 2018

evaluation

present

to

to

to

to

to

to

to

Nobuyuki
Taniguchi

Department of Laboratory
Medicine, Jichi Medical
University
Department of Mental
Hisanori Hiro
Health,InstituteofIndustrial
Ecological
Sciences, University ofOccupational
andEnvironmental
Health(UOEH)
Hokuto Hoshi
Hoshi General Hospital,
PublicInterest
Incorporated Foundation
Miyagawa
Hospital,
Megumi
MedicalCorporation
Miyagawa
Association Seiikai /Department of Endocrine
andMetabolism,
Toranomon
Hospital,
Federation of National
Public Service Personnel
Mutual Aid Associations
Nuclear
Fuel
Cycle
TakumaEngineering Laboratories,
MomoseSector of Nuclear Fuel,
Decommissioning
and
Waste
Management
Technology Development,
Japan Atomic Energy
Agency (JAEA), National
ResearchandDevelopment Agency
Shinji Yoshinaga Division of Radiation BioMedical
Informatics,
DepartmentofEnvironmetrics
andBiometrics,
Research
Institute for Radiation
Biology and Medicine,
Hiroshima University

Professor
Professor

Chairperson

Dose

FY 2014

evaluation

present

Psychological

FY 2014

effects survey

present

Clinical

FY 2014surveypresent

Staff
Thyroid
Physician,Dept.
of cancer survey
Internal Med(Part-Time)FY 2014

DeputyDose
Director andevaluation
Radiation
Control
Dept. Mgr.

FY 2014

Professor

FY 2014Analysis

to
to

to
to

present

topresent

topresent

Since research participants live nationwide, cooperative medical examination bodies for research
are established based on their locations, and the number of such bodies has reached 77 nationwide.
Since many persons are in charge of the survey, standardization of the survey method is not easy.
Therefore, the standard exchange of collected information is enabled by establishing an information
network connecting each of the cooperative bodies, and the responsible person in charge of the healthsurvey of this research and the research coordinator (RC) were appointed to periodically standardize
the interview method, and a seminar on professional skills is held.
In addition, in order to keep the technology and methods for medical examination implementation11（ 11 ）−33−

and the long term preservation of collected blood and urine invariables, specimens collectednationwide are gathered in one inspection body to perform the dispensation of preserved specimens
and the biochemical examination unitarily.
It can be said that maintaining a high quality survey is essential in order to avoid variation of thesurveys being taken into the risk evaluation. The implementation of the seminar for the standardization
by gathering the research coordinators (RC) is well evaluated, and the progress of the improvementof infrastructure for constructing a future research system in the first period including the approaches
of inspection, etc. in each of the above-mentioned research fields has also been well evaluated.
Chapter II

Proposal to research in the second period

Chapter II describes the proposal about the ideal state of the research in the second period onwards,
based on the evaluation, etc. of the research outcome in the first period described in Chapter I.
1. Securing research participants
In the five years of research in the first period, we had obtained 7,270 participants as of October 2018,
and conducted medical examinations for 5,133. Since the locations of subjects are dispersed over many
prefectures, considering the difficulty of follow-up for persons who do not belong to a limited region or
workplace, it can be well evaluated that a suitable invitation to each subject to participate in the researchand the following health survey were successfully implemented. However, an approach to secure andmaintain participants over a long period in the future is required. Therefore, it is necessary to examine
the above-mentioned approaches to secure and maintain from both the aspect of the research purpose
and also the advantages for research subjects. Specifically, we ask that an early study be performed toclarify whether the medical examination items are in accordance with each research policy and arenecessary and sufficient to ensure the research is not haphazard, but is looking toward the future and towhether the needs of examinees are being satisfied by the responsible supervising research body. For
example, reexamination should be performed from the viewpoint of whether the examination items
aiming for the discovery of disease at the time of the survey, such as cancer tests should be conducted inthis research, and whether they are examination items enabling observation of the change of the degreeof health over the future. Additionally, the research, etc. to check whether the medical examinations are
conducted according to the manual, the review of reasonability, etc. of the manual, and whether the
research based on the demand survey of the research subjects through questionnaires is performed arealso important.
This research requests participation based on free will. We ask for this approach so as to steadily
increase research participants. Based on this, it is important to continue planning and devising for
maintaining the intent without alteration for long term continuation, even when receiving an offer of
research participation once. Subsequent measures such as the improvement of the consulting system12（ 12 ）−34−

based on the medical examination results and the improvement of the environment for the purpose ofutilizing the examination results for self-health control have been so far considered, and it is importantthat these measures satisfy the needs of the research participants.
The subjects of this research can be roughly divided into the following 3 × 2 groups:
A. Working conditions at the time of survey① Workers who are still involved in radiation tasks even at this moment② Workers who were already transferred to a task other than radiation③ Persons who retired from all professions
B. Category of task at the time of emergency work(a)Specific emergency worker(b)Non-specific emergency worker

Each of the specific emergency workers and non-specific emergency workers is included in all thecategories of ①, ② and ③. Specific emergency workers are persons with an exposure dose of 50 mSv
or more during emergency work, and the Ministry of Labour, Health and Welfare performs long term
health control such as cancer tests based on the policy of the Minister. Information on the specificemergency workers necessary for this research team will be provided after submitting an application to
the Ministry of Labour, Health and Welfare.
However, retired persons, etc. of ③ who are non-specific emergency workers of (b) (③ × (b) group)
are not included as a subject of health control by the companies stipulated in the Industrial Safety and
Health Law, such as the general medical examinations and the special medical examinations of theOrdinance of the Prevention of Hazards due to Ionized Radiation, and this group is estimated to increaseat a speed of about 500 persons per year. Since the emergency workers are receiving health consultationand guidance from the Ministry of Labour, Health and Welfare, and participation in this research toperiodically receive health consultation is useful for the health control of the persons in ③ × (b) group,
we should selectively appeal to the persons in this group to have them participate in the research together
with MLHW in the second period. In addition, it is also necessary to normalize the health consultationthat has been implemented in this research because the number of medical examinees greatly fluctuatesyear to year.
The matter most difficult and requiring much effort in the cohort survey is to follow up on the survey
subjects. The transfer of the subjects is anticipated to be more frequent, and it is inevitable that thefollow-up will encounter more difficult situations in the geographical conditions in the future. In addition,
the researchers side should continuously maintain the motivation of integrating the long term researchover a period of 40 years or more. It is important to establish a follow-up survey system considering
these two points in the future.
2. Scientific evaluation of health effects of radiation exposure under emergency work13
（ 13 ）−35−

(1) Statistical detection power and analysis method
Although the figure of 7,200 persons × 40 years = 288,000 person-years is not small in theepidemiologic field targeting persons who suffered radiation exposure by accident that is handled bythis research, there is no guarantee that the detection power capable of detecting 80% of a 10%
increase in the crisis risk of cancer is obtained even if we follow up this cohort for 40 years. However,this does not mean that no continuous implementation of this cohort survey is required. The important
point is contained in the interpretation of the results. That is to say, even when this cohort survey does
not clarify the increase of risk, the cohort survey should be continued after recognizing that throughinterpretation of the results, it cannot necessarily be said that no effect on health is caused by theexisting radiation exposure, and the results should be publicized sequentially.
Since the expectation value is large if taking all cancers into account, it is considered that there is apossibility that the data may be significant when taking particular types of cancer (including thyroid
cancer) into account, although the detection power at the standardized affection ratio (SIR) = 1.1
corresponding to 10% excessive occurrence may be insufficient. We considered the re-calculation of
detection power for each cancer type, including thyroid cancer, against 288,000 person-years.
Although the recruitment of new subjects is important, it has also been judged that ensuring followup of the 7,270 persons currently secured is more important. Since neither human nor monetary
resources can ever be said to be sufficient, we ask to establish the targets strategically.
The employees of large scale enterprises belong to the population where healthy workers effect(HWE) exists, so a simple comparison with the general population having different socioeconomicalfactors cannot adjust the important socioeconomical confounding factor, and the selection bias cannot
be avoided. For example, since the cancer morbidity is lower in comparison with the general
population group, there is a high possibility that SIR is underestimated. In order to reduce suchselection bias, we consider that we should compare with the emergency workers among TEPCO’s
employees by adding TEPCO’s employees who have the same factor and are not involved in theemergency work to the research subjects as an internal control population. We should not draw aconclusion for carcinogenesis (including thyroid cancer) and cataract that are especially important
outcomes only in comparison with the general population.
(2) Confounding factor
Handling of the confounding factor is one of the vital points of this research, and it should beclarified that the department in charge is responsible for the supervisory research institution.
The adjustment of the confounding factor is often implemented by obtaining the answer of “Yes”
and “No.” For example, LDL-chol (low density lipoprotein cholesterol) has a strong relationship withalcohol drinking and smoking. When handling alcohol drinking and smoking for the adjustment of
the cofounding factor, it is expected that the adjustment using a continuous variate and multi-segment14（ 14 ）−36−

category enables analysis in higher sensitivity, but not using the answers of “Yes” and “No.” It ispreferable to adjust the cofounding factor by entering the data in the model formula as a continuous
amount if the data can be handled as a continuous amount with no reduction of the information amount.
(3) Dose evaluation
Dose evaluation is important as it affects the detection power and the reasonability of results in theepidemiology of radiation. When examining from this point, the following points can be taken up astasks:
Since the entire dose distribution deviates to the low dose side, it will be necessary to improve theaccuracy of the data of workers who were exposed to doses as high as more than 250 mSv, and to also
estimate the dose of organs other than the thyroid due to the inhalation of radioactive iodine that is its
main factor. At this time, it is necessary to estimate the contribution of Te-132, I-132, etc. that areradioactive nuclides with a short half-life. Since external exposure has been evaluated based on theeffective dose measured by the personal dosimeter, etc. of workers, we recommend to minutely
examine the data of the nuclide analysis performed using the whole body counter implemented in theearly stage, and to verify the abundance ratio of radioactive nuclides of a short half-life. In addition,in order to investigate the accuracy of dose evaluation of workers who were exposed to doses as highas more than 250 mSv, the investigation of the translocation of peripheral blood lymphocytes shouldbe performed as biological dose evaluation, if necessary.
Since the dose evaluation of only I-131 may cause insufficient evaluation of the early radiation dosefrom March 12 to 15, 2011 when it is estimated that the exposure to short half-life nuclides other thanI-131 was large, the accuracy of dose evaluation should be raised.
In addition, although the exposure evaluation of the thyroid has been so far performed by the
National Institute of Radiological Sciences based on the effective dose, it is necessary also to evaluate
it based on the thyroid equivalent dose considering thyroid disease.
Although the dose of crystalline lens for the study of cataract is subjected to the dose division basedon the effective dose, the subjects should be divided based on the crystalline lens dose evaluation
added with β dose. Further, we recommend that the dose evaluation working group examines theverification by sample survey, etc. as to whether the deviation exists between the effective dose
distribution and the crystalline lens dose distribution in the early stage.
The largest task when implementing the epidemiologic survey for a long period of time is the
medical evaluation of subjects about exposure dose. We should search the method for acquiring theinformation necessary for dose evaluation, such as photographing condition by clarifying the numberof times high-dose IVR (interventional radiology) and CT (computed tomography) were implemented
through a questionnaire survey, and obtaining the cooperation of the inspection institution. Therefore,
it is necessary to examine the system for establishing and collecting the database of medical exposure15（ 15 ）−37−

for each worker. In addition, the completion of a system capable of periodically performing
information exchange including the dose information in linkage with the epidemiologic survey ofradiation workers implemented by the Radiation Effects Association through the entrustment of the
Nuclear Regulation Authority should be also examined.
From other viewpoints, it is necessary to examine whether the exposure should be evaluated for the
analysis based on the continuous amount or based on the category.
(4) Survey of cause of death and cancer morbidity
a. Follow-up on cause of death and cancer morbidity
The cause of death and cancer morbidity working group considers that the acquisition ofagreement and follow-up are most difficult. Since the opinion exists that the comparison with deathslips of the vital statistics of the population has no problem if it explained that the occurrence ofdiseases and life-and-death situations are followed up at the survey start stage concerning theagreement of follow-up on the cause of death, it is necessary to verify again what level of agreement
is required. Although agreement is not considered to be necessary concerning death and the followup on cause of death at the start of the first period research, the necessity of the agreement was
judged from the opinions, etc. of the competent authorities, and the acquisition of agreement“concerning the follow-up on cause of death as research” was implemented through medical
examinees, mail and the Web. The agreement for the follow-up survey of cause of death and forthe comparison with resident cards has actually been acquired from 6,164 persons among 7,270
research participants as of October 31, 2018, and agreement for the collection of cancer registration
information has been acquired from 6,220 participants. These are the result of great effort, and theconsent ratio is about 1/3 of the total number of subjects. Therefore, it is necessary to aim for the
improvement of the ratio of agreement consent in cooperation with the survey project of existing
conditions of emergency workers being implemented by the government in order to make efforts
to further acquire agreements.
Although it is said that the development of software for comparing the name and date of birthwith a death slip is performed to verify the death and cause of death, there is a possibility that
persons having the same first and last names cannot be distinguished. It is necessary to clarify therate of accuracy of comparison with the death slip of vital statistics that can be performed in theearly stage of the second period research. It is necessary to minutely investigate the accuracy ofgrasping this point because the subjects are distributed nationwide and the acquisition of address
information is limited, and to further examine the follow-up method if the grasp rate is low. On theother hand, since the government performs follow-up work of emergency workers addresses tomake sure of the situation, it is also planned to identify the cause of death by referring to the deathslip based on the information obtained by the application to Ministry of Labour, Health and Welfare.
16（ 16 ）−38−

It is necessary to minutely examine with how much accuracy death identification can be performed
based on the information from MLHW in the early stage of the second period.
Although the comparison work with the cancer registration for cancer morbidity was not
performed in the first period, it is necessary to verify the grasp rate that can be compared with thecancer registration information in the research of the next period. Although cancer registration was
performed in prefectures all over Japan, there is prefectural variation in the accuracy, and thecomparison work should also be improved. If there is a challenge in comparison with cancer
registration, the utilization of receipt information for grasping cancer morbidity is helpful. Since it
is said that agreement to the comparison with receipt information was obtained from some healthinsurance societies, the method for obtaining and utilizing this receipt information should be
examined.
b. Scientific evaluation
In order to analyze the cause of death and to calculate a standardized death ratio and thestandardized morbidity ratio to evaluate the causal relation to exposure, the determination of theinformation on the exposure dose distribution and the linkage between the analyses of cause ofdeath, standardized death rate and standardized morbidity rate, as well as the information on
exposure dose distribution is the premise of the analyses.
The accurate evaluation of radiation effects is difficult based on information in the stage short on
follow-up years. Concerning the period of the analysis of the cause of death and the cancer
morbidity, follow-up over the lifetime is required because the analysis of the cause of death requires
at least 10 years or more considering the sample size, and the detection power and the result of thetrial calculation that the determination of an increase of 10% requires 40 years or more were
publicized, especially concerning cancer morbidity.
In addition, we should examine the necessity, etc. for adding TEPCO’s employees who have thesame socioeconomic factors and are not involved in emergency work to the internal control
population, considering HWE for starting analysis.
(5) Survey of thyroid cancer morbidity
a. Radiation exposure and adult thyroid cancer
Almost all the results of the surveys concluded that no relevancy was recognized between
radiation exposure and adult thyroid cancer (Note 1). It is anticipated that no increase of thyroid
cancer due to exposure will be recognized in the Fukushima Nuclear Power Plant accident where
the number of subjects was small and the majority of workers are adult males when judging fromthese epidemiologic survey reports. However, it is estimated that owing to the screening effect ofultrasonic tests, thyroid cancer will be discovered exceeding the morbidity of the general populationthat is not subject to ultrasonic test screening. Incidentally, the frequency of potential thyroid cancer
17（ 17 ）−39−

in adult Japanese is 1.5% to 21% even in males, although it varies depending on the method ofsampling slices at the time of autopsy. In order to correctly judge the dose effect relationship, it isnecessary to conduct the thyroid test in the same extraction rate not only for the high dose
population but also for the low dose population to avoid the generation of bias.
Note 1. Epidemiologic survey of survivors exposed to the atomic bomb in Hiroshima/Nagasaki (life survey LSS
and adult health survey AHS) has examined the long term radiation effect on the thyroid. The dose effectrelationship dependent on age is strongly recognized in thyroid cancer, the younger a subject is at the timeof exposure, the higher the cancer risk is, and the risk is small when a subject is 20 years old or more at
the time of exposure. The analysis by Furukawa revealed that no significant risk rise is observed for bothmale and female adults even when continuing follow-up for 60 years (Int. J. Cancer: 132: 1222-1226,
2012). On the other hand, although the analysis by Richardson et al. including micro cancer discoveredby autopsy cases recognized the significant dose effect relationship in females 20 years old or over at thetime of exposure, they did not recognize the effect in males (Epidemiology: 20: 181-187, 2009). In
addition, INWORKS study of Richardson et al. observed the increase of thyroid cancer although the data
is not significant (Epidemiology: 29: 31-41, 2018).

b. Radiation exposure and benign thyroid disease
On the other hand, various conclusions concerning the relationship between radiation exposureand benign thyroid disease are publicized, and the results of this survey are expected to bringvaluable data. Although the survey of atomic bomb victims assuming tubercle and cyst as the end
point found a significant dose effect relationship in the population that was 20 years old or less at
the time of exposure, the risk to the population 20 years old or over was not significant in thesituation of high dependency on age (Imaizumi et al. JAMA: 295: 1011-1022, 2006). Since theconclusion concerning autoimmune thyroid disease or autoantibody was divided, the survey results
this time will add the valuable data.
One of the conclusive effects of radiation exposure is thyroid hypoparathyroidism. Clinicalthyroid hypoparathyroidism is observed in the absorbed dose of 18 Gy or more in case of medical
exposure. The possibility of the occurrence of subclinical (although a TSH rise is found, the thyroid
hormone is within the reference value) thyroid hypoparathyroidism is pointed out even in lower
doses. However, evidence for this is still poor (Note 2). Since this survey is participated in by the
subjects whose thyroid equivalent dose exceeds 2 to 3 Sv, valuable data is considered to be provided.
Note 2. After the hydrogen bomb test in Bikini Atoll, Larson et al. observed subclinical thyroid
hypoparathyroidism case in the inhabitants of Marshall Islands (JAMA: 247: 1571-1579, 1982). Since
lower age inhabitants showed a higher thyroid absorbed dose, the age dependency of subclinical thyroid
hypoparathyroidism was not clarified. On the other hand, the survey of the Marshall Islands inhabitants
conducted by Takahashi et al. in the 1990s did not recognize the dose effect relationship to the thyroid
function, and the relationship between a mild iodine deficiency and the thyroid tubercle was estimated18（ 18 ）−40−

(Int J Epidemiol.28: 742-749, 1999).

c. Points to be surveyed selectively(a) Thyroid cancer: The survey assuming thyroid cancer as the end point has limitations
biologically and from the viewpoint of statistical power. However, the possibility that thyroid
cancer is discovered in a frequency higher than the morbidity statistics thanks to the screening
effect is considered. Therefore, the thyroid test should be conducted by setting a comparison
control group in the same extraction rate including the low dose group in order to avoid thedata being biased. Further, we would like to recommend comparing and examining after
conducting thyroid biopsies for abnormal persons in the same criteria and completely
integrating the criteria for non-operative follow-up observation (active surveillance) when adoubtful case was found. Although the medical examination rate of the thyroid test by theNEWS study so far is 12.2% (2,424 persons among 19,808 persons), the higher effective doseshows the higher examination rate of the ultrasonic test and the ratio of judgment B presents
a trend of increase. The consultation guidelines for Japanese thyroid cancer recommends theactive surveillance for thyroid cancer having low risk. However, since the subjects who areaware of high dose tend to desire surgery earlier than the active surveillance, careful responseby clinical departments is requested.
(b) Benign thyroid disease: Since tubercle and cyst are discovered in high frequency, it isexpected that useful data are brought. Although it is known that the ratio of Japanese having
potential cancer is high, there is a possibility that the survey this time provides new knowledge
concerning the natural history of adult thyroid tubercle. The subclinical thyroid
hypoparathyroidism can be observed in the population with exposure to a high dose.
A certain amount of data should be summarized until the time 10 years after the start of thesurvey as a target.
(6) Survey of cataract
The definition of “prevalence rate of cataract” should be clarified, and whether the change thistime is cataract or shows only the degradation of the crystalline lens should be clarified.
The method for selecting subjects should be clarified, and the inclusion of TEPCO’s nonemergency workers in the internal control population should also be taken into consideration. This
enables the unification of the distribution of age and sexuality.
Since the radiation dose this time uses the effective dose, it is expected that the usage of theabsorbed dose of crystalline lens prevents the deviation from the actual radiation dose.
The definition of cataract that stipulates the prevalence rate of cataracts should not be a unique
one to this research, but should conform to the international definition, the guidelines of relevant
academic societies, etc. and should be evaluated using the most general inspection method. If the19（ 19 ）−41−

definition of cataract and its inspection method are reviewed in the relevant academic societies, etc.
in the future, the results of the study of how the results of the EAS-1000 that is the standard ofcurrent cataract study and the simplified transillumination camera correlate should be assumed as
the premise for promoting this research, and it will be preferable to install as many simplified
transillumination cameras in medical examination facilities as possible. In addition, unification ispreferable so that the method of filling in the observation sheet of the test is uniform, and the final
evaluation determination is preferable to be universal but not personal determination. Therefore,
the development of the system for automatically measuring the opacity of the crystalline lens is
expected.
(7) Survey of psychological influenceThis survey is to indirectly evaluate the disease and the exposure dose effect differing from othersurveys. Therefore, we recommend proceeding with the research of the second period after clarifying
the purpose and the arrival point of this survey.
The improvement of the follow-up accuracy is important to provide knowledge of the ranking
among the countries of the world in the psychological influence evaluation. The acquisition of theoutcome of suicide deaths, etc. asked in the question and answer is also recommended to be examined.
Since the especially important knowledge about depression and alcohol drinking behavior isconsidered to have been obtained, we ask you to continuously analyze so as to enable the comparisonof frequency with the general population after the adjustment of age, etc. On the other hand, whencomparing with the general population, the selection of subjects to be compared is also important, and
it is necessary to minutely examine the confounding factors among the background factors including
age. After that, we especially wish that a paper concerning the following knowledge is written at an
early stage.
1. The frequency of “major depressive disorders (DSM-IV)” and “severe depression episodes
without psychotic symptoms (ICD-10)” at the time of baseline (at the time of survey) compared withthe data of the general population as well as the crisis rate before and after the disaster. We ask you to
examine whether the comparison with the precedent research by Shigemura et al. provides a certain
consideration point. In addition, we ask you to continuously examine the PTSD-related symptoms thatseem to be analyzed concerning the period of entry.
2. Papers concerning stigma and relevant factors including discrimination and slander by thesurrounding people, mental health, etc. while taking into consideration the abnormal situation after anuclear disaster.
In addition, although “the usefulness of K6 in evaluation concerning depression is suggested” isdescribed, since K6 is for measuring structural concepts differing from depression (psychologicaldistress), this interpretation is not generally accepted. Although it is not incorrect that K6 evaluates an20（ 20 ）−42−

aspect of the mental health degree itself, even if K6 is used in the long- and middle-term follow-up
survey from now, the evaluation should be performed by separating it from the knowledge obtained
from the research this time.
3. Research system
Since this is research to be performed over a long period of time, the main constituent of the researchshould not be transferred during the research period. For example, the training of structuring interviews
was performed by making great effort. We wish to prevent the dissipation of the research resources
including human resources and continue research utilizing these resources. A stable infrastructure systemthat copes with the changes in various social regions and enables the maintaining and continuation of thisresearch throughout the lifetime of the subjects should be established.
Since the situation that the system for starting the second period was incomplete at the end of the first
period was a big problem from the viewpoint of the continuation of the research, reexamination of theresearch continuation system is required. As a result, since the supervisory organization was notdetermined for two months from April to the beginning of June just after the first period had ended, all
medical examinations and research were stopped. Specific problems concerning this are listed below:
・ Problems related to the continuous follow-up of survey subjects
The absence or change of the supervisory body was a great disturbance for maintaining the continuanceof the conference and maintaining and developing the outcomes so far obtained, even if it is once every
five years, because the tasks of inviting participants and reserving medical examinations were promoted
by relying on a cooperative relationship with various external bodies. For example, we could not give
clear reply to inquiries from research participants concerning the restart period because the consultation
reservation system was stopped during this period, and it is feared that this disturbed the maintaining of
the eagerness for participation.
・ Problems related to safety control of research resources
Since this research necessitates the safe accumulation of personal information requiring carefulconsideration for a long period of time, the establishment of a continuous control system including theconstruction of a network system is necessary. Therefore, the current method of public invitation of asupervisory body every five years is not suitable from the viewpoint of stably maintaining this.
・ Problems related to long term storage facility, etc. of biological specimens
Since the biological specimens collected in this research are presumed to be stored and maintained fora long period of time, the change of the supervisory body in charge greatly disturbs the maintaining of
stable storage considering the labor, expense and time for changing and transferring the stored devices.
Chapter III

Summary

The evaluation by this committee concerning the research results of the five years in the first period of21（ 21 ）−43−

the “Epidemiological Study of Health Effects in TEPCO Fukushima Daiichi Nuclear Emergency Workers”
was described as above. We evaluate that the research was steadily promoted in the first period (2014 to2018) in general, and also show the proposal by this committee concerning the ideal state of the five yearsof research in the second period. This research is now in progress, and although some contents may not
immediately be incorporated in the research, this committee desires to cope with the tasks elastically byincorporating the results in a future research plan because this research will continue for a long period oftime. In addition, we ask the Ministry of Labour, Health and Welfare to assist with the promotion of thisresearch by proceeding with the evaluation of the research, so as to realize the contents of this researchand taking actions for securing the research budget, etc. in the form following the above.

22（ 22 ）−44−

Industrial Disease Clinical Research Grants fromJapanese Ministry of Health, Labour and Welfare

Epidemiological Study Targeting Nuclear Emergency Workers
at the TEPCO Fukushima Daiichi Nuclear Power Plant
General Research Report(Excerpted Version)

Principal Investigator: Toshiteru Okubo
March 2019−89−

Table of Contents
I. Comprehensive Research Report
Epidemiological Study Targeting Nuclear Emergency Workers at the TEPCO Fukushima Daiichi
Nuclear Power Plant ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 1
Toshiteru Okubo
II. Working-Group Research Reports (by Individual Subcommittees)
1. Approaches to the Study Target Population: Characteristic analysis of the Study Target
Population ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 23
Toshiteru Okubo
Statistical Detection Power in the Follow-Up Study on the Number of Emergency Workers 39
Toshiteru Okubo
2. Clinical Survey Subcommittee
Toshiteru Okubo ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 39
Hokuto Hoshi ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 91
3. Cataract Working Group
Hiroshi Sasaki ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 109
4. Thyroid Cancer Survey Subcommittee
Tomotaka Sobue ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 115
5. Psychological Impact Survey Subcommittee
Hisanori Hiro ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 177
Jun Shigemura ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 253
6. Cause-of-Death/Cancer Incidence Survey Subcommittee
Kotaro Ozasa ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 271
7. Dose Assessment Subcommittee
Makoto Akashi ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 273
8. Radiobiological Study Working GroupRyuji Okazaki ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 285
List of Published Research Outcomes ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 303−90−

I. Comprehensive Research Report−91−General Research ReportIndustrial Disease Clinical Research Grants
Comprehensive Research Report

Epidemiological Study Targeting Nuclear Emergency Workers at theTEPCO Fukushima Daiichi Nuclear Power Plant
Principal Investigator: Toshiteru Okubo, Radiation Effects Research Foundation (RERF), Consulting
Researcher
Abstract
In the accident response work at the TEPCO Fukushima Daiichi Nuclear Power Plant, the radiation emergency
exposure dose limit was raised from 100 mSv to 250 mSv for the period from March 14, 2011, to December 16 of
the same year. During this period, 174 individuals among the approximately 20,000 people engaged in the work are
estimated to have been exposed to doses exceeding the five-year normal work exposure limit of 100 mSv. This study
aims to perform a lifelong follow-up of the entire emergency workforce of approximately 20,000 persons toinvestigate the relationship between their radiation exposure and health.
From the start of the appeal to the emergency workers living in Fukushima Prefecture in FY 2014, during theentire period until FY 2018, 19,808 emergency workers in the whole country responded as follows, 7,270 (36.7%)
showed interest in participation, 3,334 (16.8%) declined participation, 6,976 (35.2%) returned no response, and 1,828(9.2%) were addressees unknown at the address used.
The progress made in this study for each fiscal year was generally as follows: in FY 2014, we performed
preparatory work for a country-wide launch of the survey by identifying challenges such as how to establish
interview/health examination footholds, how to brief the outline of the survey, how to obtain informed consent, how
to work with research partner institutions, and how to receive survey data. In FY 2015, we developed a network of
70 or so research partner institutions to establish clinical survey footholds all over the country. In FY 2016, we started
a full-scale campaign to encourage emergency workers to participate in this study. The encouragement of TEPCO
employees to take a health checkup was also started, which had been postponed due to the preparatory work forcooperation by TEPCO in this survey. Moreover, an information network system was developed, including
application systems such as a "health questionnaire handling system" to be used by health checkup institutions and a"health checkup scheduling system" for making checkup appointments on the Web. We also started an integrated andstandardized operation of the health examining methods and blood and urine sample tests at all research partner
institutions. For the purpose of the cause-of-death/cancer incidence survey, we continued to undergo formalities touse demographic survey death certificates outside the intended purpose, and made preparations to collect information
including causes of death. For FY 2017, we decided to place the focus on secondary campaign approaches. We newly
started PR activities through posters and websites. In addition, we prepared flyers and asked for their inclusion in
mail to be delivered to personal addresses on such occasions as the Current Status Survey, conducted as part of the
MHLW long-term health management of the emergency workers. In FY 2018, health checkup appointment
coordination tasks were outsourced.
Steadfast progress has also been made in clinical studies (by the Clinical Survey Subcommittee focusing on
general health checkups, the Thyroid Cancer Survey Subcommittee, and the Psychological Impact Survey
Subcommittee), exposure dose reconstruction by the Dose Assessment Subcommittee, and health effect-related
surveys (by the Cause-of-Death/Cancer Incidence Survey Subcommittee and others). We, however, have not reacheda definite conclusion because the encouragement of the study target population to participate is still in progress. To
evaluate health effects, we should refrain from discussing causal relationships until various social factors are
sufficiently evaluated as confounding factors lying in between.

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Names, organizational affiliations, and titles of Co-Investigators
Makoto Akashi

National Institutes for Quantum and Radiological Science and Technology Executive Officer(QST), National Research and Development Agency
Waka Oishi
Hiroshima Clinical Research Department, Radiation Effects Research Department
Foundation (RERF), Public Interest Incorporated Foundation
Director
Ryuji Okazaki
Department of Radiological Health Science, Institute of Industrial Professor
Ecological Sciences, University of Occupational and Environmental Health(UOEH)
Kotaro Ozasa
Hiroshima Department of Epidemiology, Radiation Effects Research Department
Foundation (RERF), Public Interest Incorporated Foundation
Director
Fumiyoshi Kasagi (Retired) Institute of Radiation Epidemiology, Radiation Effects Institute Director
Association (REA), Public Interest Incorporated Foundation
Hiroaki Katayama (Retired) Department of Information Technology, Radiation Effects Department
Research Foundation (RERF), Public Interest Incorporated Foundation
Director
Kazuaki Kawai
Department of Environmental Oncology, Institute of Industrial Ecological Professor
Sciences, University of Occupational and Environmental Health (UOEH)
Hiroko Kitamura Hiroshima Clinical Research Department, Radiation Effects Research Deputy
OfficeFoundation (RERF), Public Interest Incorporated Foundation
Head
Eunjoo Kim
Department of Radiation Measurement and Dose Assessment, National Researcher
Institute of Radiological Sciences (NIRS), National Institutes for Quantum
and Radiological Science and Technology (QST), National Research andDevelopment Agency
Osamu Kurihara
Department of Radiation Measurement and Dose Assessment, National Department
Institute of Radiological Sciences (NIRS), National Institutes for Quantum Director
and Radiological Science and Technology (QST), National Research andDevelopment Agency
Kazunori Kodama Radiation Effects Research Foundation (RERF), Public Interest Principal
Incorporated Foundation
Researcher
Hiroshi Sasaki
Department of Ophthalmology, Special Research Division / Division of Professor
Vision Research for Environmental Health, Kanazawa Medical University
Jun Shigemura
Department of Psychiatry, Department of Medicine, Faculty of Medical Associate
Education, National Defense Medical College
Professor
Yumiko Suto
Department of Radiation Measurement and Dose Assessment, National Team Leader
Institute of Radiological Sciences (NIRS), National Institutes for Quantum
and Radiological Science and Technology (QST), National Research andDevelopment Agency
Tomotaka Sobue
Environmental Medicine and Population Sciences, Department of Social Professor
Medicine, Graduate School of Medicine, Osaka University
Kotaro Tani
Department of Radiation Measurement and Dose Assessment, National Researcher
Institute of Radiological Sciences (NIRS), National Institutes for Quantum
and Radiological Science and Technology (QST), National Research andDevelopment Agency
Nobuyuki
Department of Laboratory Medicine, Jichi Medical University
Professor
Taniguchi
Hisanori Hiro
Department of Mental Health, Institute of Industrial Ecological Sciences, Professor
University of Occupational and Environmental Health (UOEH)
Hokuto Hoshi
Hoshi General Hospital, Public Interest Incorporated Foundation
Chairperson
Megumi
Miyagawa Hospital, Medical Corporation Association Seiikai / Department Staff
Physician,Miyagawaof Endocrine and Metabolism, Toranomon Hospital, Federation of National Dept. of Internal
Public Service Personnel Mutual Aid Associations
Med (Part-Time)
Takuma Momose Nuclear Fuel Cycle Engineering Laboratories, Sector of Nuclear Fuel, Deputy Director
Decommissioning and Waste Management Technology Development, andRadiation
Japan Atomic Energy Agency (JAEA), National Research and Control Dept. Mgr.
Development Agency
Shinji Yoshinaga
Division of Radiation Bio-Medical Informatics, Department of Professor
Environmetrics and Biometrics, Research Institute for Radiation Biology
and Medicine, Hiroshima University

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FY 2014 topresent
FY 2014 topresent
FY 2014 topresent
FY 2014 topresent
FY 2014 to2017
FY 2014 to2017
FY 2017 topresent
FY 2017 topresent
FY 2018 topresent

FY 2014 topresent

FY 2014 to2017
FY 2014 topresent
FY 2015 topresent
FY 2014 topresent

FY 2014 topresent
FY 2018 topresent

FY 2014 topresent
FY 2014 topresent
FY 2014
FY 2014 topresent
FY 2014 topresent

FY 2014 topresent

A. Study objective

For this study, we are collecting all relevant existing

In the accident management work at the TEPCO Fukushima

materials, including exposure dose measurements taken during

Daiichi Nuclear Power Plant, the radiation emergency exposure

the emergency work and the results of health checkups done bydose limit for workers was raised from the normal value of 100

the relevant enterprises in the past. Moreover, we shall also

mSv/5years to 250 mSv/5years for the period from March 14,

continuously obtain radiation exposure- and health-related

2011, to December 16 of the same year. It was estimated that

information to be collected in the future by these related

174 individuals among the approximately 20,000 people

organizations from the survey target population. In this study,

engaged in the work had been exposed to doses exceeding theperiodic address checks, clinical studies, interview surveys, andfive-year normal work exposure limit of 100 mSv during thisother activities shall be continuously performed to keep lifelong

period. This led to concerns over radiation-induced healthtrack of the whereabouts of the study target population anddisorders. Meanwhile, a majority of the workers experienced ancollect information on radiation exposures and its health effects.

exposure dose of less than 100 mSv. Therefore, it was required

At the same time, materials and test samples shall be maintained

to conduct reliable epidemiological surveys with confoundingfor use in new individual studies to be planned in the future.

factors such as lifestyle habits taken into consideration, in order

Where any study information related to this study has been

to determine the presence or absence of diverse health effects,

obtained during the previous research grant-funded project

including the psychological impacts of low-dose exposures andconducted on the same target population as the present one

to clarify their mechanisms. Besides, the need for such surveys

before the start of this study, formalities shall be followed to

was pointed out by the United Nations Scientific Committee ontake over such information for this study.

the Effects of Atomic Radiation (UNSCEAR) and the

The first phase of the study period shall be five years (until

International Atomic Energy Agency (IAEA). Thus, a survey

the end of March 2019), during which time a group shall befor identifying the health effects of radiation exposure on

developed that will form the basis for the cohort. Whileemergency workers was planned as a national subsidized

intended for lifelong follow-ups of the target population, thisproject. This study is a prospective cohort study on all of thestudy shall be evaluated every five years by a third-party

approximately 20,000 persons registered in the Ministry ofcommittee consisting of external experts.

Health, Labour and Welfare (hereinafter "MLHW") Long-Term

3) Health effects to be evaluatedHealth Management System (hereinafter referred to as the

The health effects to be evaluated in this study fall within the"Long-Term Health Management System") for Workers at thefollowing scope:

TEPCO Fukushima Daiichi Nuclear Power Plant. This studya) Malignant tumors (leukemia, thyroid cancer, etc.);

aims to evaluate the relationships of radiation with cancer andb) Non-cancerous diseases (circulatory system diseases,

other various results. Additionally, blood and other biologicaltest samples shall be retained to help develop biologicalcataract, thyroid diseases, etc.);c) Psychological impacts (PTSD, adaptation disorders,dosimetry and to prepare for studies on the action mechanismsof radiation effects, if results suggestive of radiation effects

depression, etc.);d) Biological indicators for evaluating the mechanisms of

become apparent.

radiation health effects (immunosenescence indicators,

The promotion of this study is expected to compare the futurechronic inflammatory indicators, etc.) and molecularincidence of disease among workers engaged in emergency

biological indicators (single nucleotide polymorphism,

work with that of the same disease among other groups ofpeople, thereby helping to determine the relevance of the

genome sequence analysis, DNA adducts, etc.);e) Health indicators that may be found necessary in the course

disease to emergency work.

of this study in addition to those in items a) to d) above; andf) Health conditions that provide confounding factors necessary

B. Study methodology

to evaluate the health indicators in items a) to e) above.
4) Analysis of test samples and the preservation of stored

1) Study target population and study design
This study is a prospective cohort study designed to perform

samples

lifelong follow-ups of the whole emergency workforce of

To investigate the causes and backgrounds of the above-

approximately 20,000 persons. This study is based on thismentioned health effects, a long-term blood and urine sample

exhaustive survey and conducted assuming that diverse forms

storage plan shall be established to allow the biochemicalof individual studies, such as cohort, case-control, and nested

analysis of biological changes before and after the detection ofcase-control studies, will be planned for all or part of the study

any health effects. For the first 11 months following the start oftarget population in the future.

this study (from January 2016 to the end of November 2016),

2) Acquisition of existing materials and the study period

individual research partner institutions (hereinafter referred to

-3（3）
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as "health checkup institutions") performed analyses andindividual

measurements by their usual clinical test methods; then, theinstitutions for information on high radiation dose treatments

obtained numerical results were collected by the Radiationand examinations, such as therapeutic radiation exposure andEffects Research Foundation (RERF) (hereinafter abbreviatedabdomen CT examinations. Information on daily life

as "RERF"), which is the supervisory headquarters of this study.

exposure shall be obtained through interviews with target

With a large number of institutions involved in analyses,
however, long-term accuracy control is hard to maintain.

inquiretotreatment-providing

individuals.
d) Organ-specific exposure doses shall be estimated by

Therefore, we decided to outsource all tests wholesale to
Kotobiken Medical Laboratories, Inc. (hereinafter referred to as

concerned,

calculation.
e) Biological dosimetry shall be performed using tests such as"Kotobiken") from December 2016 and onwards. Since then,blood chromosome tests.

blood and urine samples from research partner institutions allf) Information shall be collected on radiation-related disease

over the country have been collected and sent to Kotobiken's

risk factors other than radiation (confounding factors).

Biken Central Research Laboratory Tsukuba (hereinafter

Psychological impact risk factors shall be collected andreferred to as the "Central Research Laboratory") where theyevaluated

are aliquoted either as clinical test samples or as biological test

questionnaire surveys. Attention shall also be paid to factors

samples for storage.

such as histories of occupational exposure to hazardous

Serum, blood cell, and urine test sample aliquots for storage

throughself-completedorinterview-based

substances.

are frozen in cryogenic freezers, transferred while being kept at6) Follow-up of the target population and collection of result

constant low temperature in dry ice to the RERF, and stored inindicators

the automated cryogenic handling and storage depository at the

We shall select one to several institutions per prefecture as

RERF. Among other things, we periodically check the required

footholds for making direct contact with target individuals

delivery time from the health checkup institutions to the Central

spread over across the country, to explain to them about thisResearch Laboratory, the lead time for testing, and the lead time

study, obtain their consent, conduct health checkups, and carryfor cryogenic refrigeration storage. We also periodicallyout other functions. We shall consign research-related tasks tomonitor the temperature during transportation to the RERF.

these institutions.

Furthermore, each health checkup institution divides samples

In addition, we shall strive to track causes of death based on

into two sets, one for in-house inspection and the other for

demographic surveys and obtain cancer incidence information

normal submission to Kotobiken, whereby the samples undergo

through the National Cancer Register.

double-blind testing to verify the accuracy of clinical tests at

While paying attention to consistency with regular health

Kotobiken.

checkups conducted as a responsibility of proprietors, we shall5) Evaluation of radiation exposure

conduct regular health checkups to collect clinical data and shalla) Information on personal exposure doses during emergency

perform questionnaire surveys, health examinations and checks,

work shall be provided through the MHLW "Long-Termbiological test sampling, and so forth. We shall also receive the

Health Management System for Workers at the TEPCO

provision of health checkup data held by proprietors.

Fukushima Daiichi Nuclear Power Plant." Based on this7) Research system
As

information, this study reexamines the exposure dose for all

regards

researchorganizations,the

Operational

the study target individuals. We shall receive the provision ofCommittee and Study Groups consisting of Working-Group

primary materials necessary for exposure dose reconstruction

Investigators shall convene for their respective meetings tofrom TEPCO and other parties that have been responsible forfacilitate efficient execution of this study. Each year, The Studyemergency work radiation control. At the same time, we shallGroups shall hold one or more Study Group Meetings with full

strive to obtain detailed information on stable-iodine intake

member attendance, to discuss study methodology, researchstatus and actual work conditions in order to improve theoutcomes, and future research policy, and other issues.

accuracy of exposure dose reconstruction.

a) Operational Committee: Supervises this Research Project asb) Information on personal exposure doses due to engagement

a whole. This Committee deliberates on all important mattersin nuclear radiation work before and after employment forfor the execution of this study, including Research Proposals,

emergency work shall be provided from the Radiation Effects

research ethics, research organizations, storage and use of

Association (REA) Radiation Dose Registration Center.

materials and test samples, allocation of research budget,
research publication, and third-party review.

c) To make dose estimations based on medical exposure, which
are is the main kind of radiation exposure other than fromb) Analysis/Evaluation Subcommittee: Performs statisticalradiation work, we shall, with the consent of each target

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analysis and evaluation of survey results.

c) Centralized control of epidemiological data and application

data and reconstruction of intake scenarios, and also performs

thereof to studies

chromosome analysis-based evaluation to achieve a multi-

No change can be made to the basic data stored in the data

faceted reconstruction of personal exposure doses. Moreserver, except for the addition of new data and corrections

specifically, the Subcommittee performs dose assessment,

made to existing data. Direct manipulation of the basic data

factoring in uncertainty, mainly through simulation-based or

is limited to authorized personnel only. Therefore,

otherwise

investigators cannot make access to basic data. For all

measurement data and reconstruction of intake scenarios

studies, the only available data is the research-use database

based on personal behavior records, with stable iodine tabletsthat contains necessary items created based on the Researchand other modifiers taken into consideration. For this purpose,

Proposal and extracted from the basic data.

the Subcommittee shall develop an exposure information

drivenverificationofinternal

exposured) Clinical Study (Health Checkup) Subcommittee: Plans,

control/dose calculation system that is able to store existing

conducts, and manages clinical studies (health checkups).

exposure and behavior record information and perform doseThis Subcommittee considers the details of the outsourcing

calculation. The existing exposure information shall includeof health checkups and performs information gathering and

REA’s records referenced for past nuclear workers and theother responsibilities. The Subcommittee also standardizes

inquiries for the results of prefectural resident health surveys

blood

conducted on Fukushima Prefecture residents to assess the

sampling, and preparation and transportation of test samples

effect of environmental exposure. For study target

for storage to ensure proper accuracy control.

individuals deemed as exposed to a dose of more than 70 mSv,

clinical tests, interviews, health examinations,e) Cataract Working Group: Conducts and manages cataract

the Subcommittee shall assess their exposure doses based on

surveys and evaluates obtained data and analysis results.

the analysis of translocated chromosome frequencies (nearlyf) Thyroid Cancer Survey Subcommittee: Conducts andmanages thyroid cancer surveys and evaluates obtained data

free of secular variations).
j) Radiobiological Study Working Group: Plans and conducts

and analysis results.

radiobiological studies using biological test samples obtainedg) Psychological Impact Survey Subcommittee: Conducts andfrom health checkups.

manages psychological impact surveys and evaluates(Ethical considerations)obtained data and analysis results. Of the data on the target

The Research Proposal for this study was reviewed andpopulation of the previous study conducted with the MHLW

approved by the RERF Ethics Committee. The individual

Grant-in-Aid for Scientific Research before the start of thisstudies planned by the Co-Investigators shall be classified bystudy, those on the target population of this study (person-

study theme to undergo ethics review by their respective

specific raw data) shall be taken over as existing materials foraffiliated institutions as necessary. This study shall bethis study (the same applies to e) and f) above).

conducted in compliance with the "Ethical Guidelines forh) Cause-of-Death/Cancer Incidence Survey Subcommittee:

Medical and Health Research Involving Human Subjects" andChecks whether the study target individuals are alive or deadthe "Ethical Guidelines for Medical and Health Researchbased on the information from the periodic status surveys

Involving Human Subjects."(including inquiries for certificates of residence) on the studya) Handling of materials and test samples

target population recorded in the MHLW "Long-Term Health

Information on the study target population shall be strictlyManagement System for Workers at the TEPCO Fukushima

protected and controlled in accordance with nationally

Daiichideceasedprescribed standards (the Personal Information Protection Act,

individuals, information, including causes of death, shall be

NuclearPower

Plant."

Regardingthe "Ethical Guidelines for Medical and Health Research

periodically collected through the formalities to use

Involving Human Subjects," etc.) The materials and test

demographic survey death certificates outside the intended

samples for this study shall be provided to the RERF as

purpose. This Subcommittee performs periodic collation

personally identifiable information by related parties, including

with the National Cancer Register to collect cancer incidence

the MHLW and other agencies possessing materials and test

information, including survivors.

samples, health checkup institutions engaged in healthi) Dose Assessment Subcommittee: Based on the exposure

checkups and surveys, and Joint-Researchers engaged indoses measured, with a focus on external exposure doses,

individual studies, and shall be centrally stored associated withduring the emergency work, this Subcommittee collects

individual target individuals. If required for research purposes,

various information before and after the work to reconstruct

only the required items shall be provided to the Research

exposure doses. The Subcommittee comparatively examines

Director after being anonymized at the RERF in accordanceinternal exposure doses through verification of measurementwith the approved Research Proposal. All correspondence

-5（5）
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tables for merging shall be securely retained by a specificc) Benefits and risks of this study for the target population

administrator designated by the RERF. Materials and test

In surveys conducted using methods such as interviews, self-

samples shall be stored in a lockable room. Personallycompleted questionnaires, or other similar methods, or in

identifiable materials shall be stored in a lockable storage

analyses of existing materials and obtained test samples, there

cabinet installed in that room. Electronic data shall be stored inare no benefits or risks to the target population. In cases such as

a dedicated server installed in a lockable room and shall betests/biological test sampling involving physical invasion,

manipulated by authorized personnel only. In principle,

minor physical risks may occur depending on the type/level ofelectronic data shall be auto-backed up on a separate server as

the test. When informing target individuals of the answers to aa precaution against unexpected failure. Additionally, copies ofquestionnaire survey or the results of a test or a biological test

magnetically recorded data shall be created at regular intervals

sample analysis, we shall give priority to providing them withand stored in a bank safe as a precaution against criticalbenefits such as easier health management. As regards

situations where all computers have become unusable. In

procedural manuals for addressing expected adverse events

principle, all data and materials shall be retained until the end

during health checkups, the manuals of individual researchof the study period (tentatively set as 30 years). Each biologicalpartner institutions shall be used mutatis mutandis or shall betest sample (such as blood and urine) shall be pre-treated for

prepared beforehand by the responsible investigator. Shouldstorage, then aliquoted into more than one tube for storage,

any such event occur, the research partner institution concernedlabeled with a suitably anonymized ID for merging, and stored

and the responsible investigator shall immediately provide

in a storage vault at −80°C. Materials and test samples shall beappropriate treatment for recovery and prevent the spread ofdisposed of as follows: primary materials (including personal

damage. Should any such event occur, the research partner

identification materials), anonymized materials for research

institution concerned or the responsible investigator shallpurposes, and anonymized correspondence tables shall be

immediately provide its details to the Principal Investigator.

disposed of separately by kind; more specifically, printed

The Principal Investigator shall report the information to thematerials shall be disposed of by shredding whereas

head of the Supervising Research Institution and shall makeelectromagnetic data shall be disposed of after physicalcontact with the members of the Operational Committee of thisinitialization. Biological test samples shall be disposed of by

study, and likewise with the research partner institutions

their respective suitable methods (specific details of which shallengaged in the health checkup concerned and necessary

be given in individual Research Protocols). Requests frominvestigators. Then, the Operational Committee shall convenetarget individuals for disposal of their materials and test samples

as soon as reasonably possible for reporting on the event

during the study period shall be accepted in accordance withconcerned and response thereto, and consider the subsequentprescribed formalities: the pertinent materials and test samples

measures to be taken. The head of the Supervising Researchshall be disposed of by transparent methods, and the results

Institution shall ask the Ethics Committee for their views on theshall be appropriately explained to the requesters and retained

event concerned and take necessary measures accordingly. For

for record.

individual Research Proposals, specific instructions shall beb) Explanations to target individuals and acquisition of theirprovided in the corresponding Research Protocols.

consentd) Release of research outcome

In this Research Proposal, after the explanation of the

When this study Group presents its research outcome at an

meaning, purpose, entity, and method of this study, target

academic conference or gets it published in a specialist

individuals shall be informed that their participation in thisacademic journal, it goes without saying that the normal

study is at their discretion. After the explanation of the benefits

standards and operational regulations practiced in the WG

and disadvantages of their cooperation in this study and theInvestigators' affiliated research institutions must be complied

rights of the participants, their consent to the items given below

with. This study, however, has attracted much public attention.

shall be obtained. Where informed consent (hereinafterHence, the contents to be presented or published by the WG

abbreviated as "IC") is difficult to obtain from a target

Investigators shall not be left at their exclusive discretion, but

individual due to reasons such as old age or poor healthshall be carefully examined for relevance with the contents ofcondition, IC obtained from their proxy may be acceptable.

the presentations and publications by the Study Group as a(i) Receiving information provided from agencies possessing

whole, including those made in the past to ensure the overall

existing materials;

consistency. The formalities to follow are described in the(ii) Clinical studies including health checkups; andfollowing paragraphs separately for presentations at academic(iii) Receiving requests for participation in individual Research

conferences and submissions to journals.

Proposals to be planned in the future.

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Presentations at academic conferences

Investigator and the Co-Investigators will occur in excess of thePrior to submitting an application for presenting at aconference, the Lead Presenter shall, as usual, obtain approvalprescribed standard.
g) Methods of information disclosure

from all members of his/her affiliated Subcommittee or

The outline of this study and other information thereon shall

Working Group and all Co-Presenters. Then, the Lead Presenterbe posted on the homepage for the external audience on theshall follow the formalities specified by his/her affiliatedwebsite of this study. A newsletter explaining the status of

institution to obtain approval for presenting. After the

progress made in this study shall be sent out to the target

completion of the internal formalities, a summary of the draft

individuals of this study once a year or so. Whenever a request

presentation shall be submitted to the Research Secretariat offor perusal is received from any study target individual, thethe RERF, which is the Supervising Research Institution. On the

Research Protocol shall be disclosed without delay.

basis of the content of the draft presentation, the Principalh) Handling of consultation requests from study target

Investigator shall determine whether to seek comments fromindividuals

other relevant WG Investigators. The Principal Investigator

Any request for consultation from a study target individual

shall inform the Principal Presenter of the approval after theshall first be received by the RC in charge thereof. After

addition of necessary corrections.

checking with the Principal Investigator or an appropriate Co-

At the same time, the Principal Investigator shall

Investigator or a Research Collaborator, the RC shall reply tocommunicate the summary of the conference presentation to thethe study target individual.

Office for Radiation Protection of Workers, Industrial Healthi)

Division, Industrial Safety and Health Department, Labour

compensations therefor

Standards Bureau, MHLW.

Economic

costs

on

study

targetindividuals

andThe health checkup cost shall be covered by the grant for thisSubmissions to academic journals

Research Project. Hence, no cost will occur to any participant.

Prior to submitting a paper to an academic journal, the LeadAs regards the cost of traveling to the research partner

Author shall, as usual, obtain approval from all members of

institutions where participants undergo health checkups, thehis/her affiliated Subcommittee or Working Group and all Co-

most economical amount for traveling by the normal route shall

Authors. Then, the Lead Author shall follow the formalities

be paid. Honoraria shall be paid as appropriate for the cost andspecified by his/her affiliated institution to make arrangement

time spent on participation in this study.

for internal peer review. After the completion of the internal
formalities of his/her affiliated organization, the Lead Author[Study results]

shall submit the abstract of the paper to the RERF Research

Outline of progress made in the study for the

Secretariat. The Principal Investigator shall determine whether

individual years

to seek comments. Should any other relevant WG Investigator

1) FY 2014

find peer review necessary, the Principal Investigator shall

In FY 2014, the initial year of the study period, a preliminary

make a request for peer review and add necessary corrections

survey of emergency workers living in Fukushima Prefecture

before informing the Principal Presenter of the approval.

was conducted to identify challenges such as how to establish

At the same time, the Principal Investigator shall submit theinterview/health examination footholds, how to brief the outline

abstract of the paper for submission to the Office for Radiationof the survey, how to obtain consent to this study, how to work

Protection of Workers, Industrial Health Division, Industrial

with partner institutions, and how to receive survey data. Then,

Safety and Health Department, Labour Standards Bureau,

preparations were made for a country-wide launch, including

MHLW.

the standardization of the methodology for full-scale surveyse) The status of progress made in this study shall be reported

and the selection of the survey results compilation method.

once a year to the MHLW, from which this study was

2) FY 2015

commissioned. Reports shall be made to the head of the RERF

In FY 2015, focus was placed on the development of aand Science Advisory Committee as necessary. In addition, theclinical survey implementation system and the encouragement

study shall be reviewed by the Ethics Committee as appropriate.

of the study target population to participate in this study. Each

After reaching a certain stage, this study shall undergo an

Subcommittee started specific planning of a Research Proposalinternational third-party review.

and made the preparations necessary to start their study, such asf) Conflicts of interest

the establishment of a research support organization. As a

A review for conflicts of interest regarding this study shall beclinical survey implementation system, a network of research

performed by the RERF Conflict of Interest Prevention

partner institutions was established consisting of 70 institutions

Committee to ensure that no financial benefit from the Principal

listed in Table 1 (increased to 77 institutions as of the end of

-7（7）
−99−

Oct. 2018 through subsequent partnership expansion efforts)"Preliminary Survey Work for Extracting Records of Exposure

with NFIHO member institutions at the core. Next, each

Doses Experienced by Emergency Workers," REA-held

institution was requested to appoint an RC in charge of thispersonal information was checked against the information on

study, so that RC meeting could convene and hold training

the participants of this study on a person-by-person basis toworkshops on, e.g., the approach to surveys as an effort toidentify potential problems. More specifically, we conducted astandardize surveys.

preliminary survey for improving the actual working accuracy

We assisted the Thyroid Cancer Survey Subcommittee andof identification with emergency workers, using the exposure

the Psychological Impact Survey Subcommittee with holding adose record consistency verification method developed in FY

training workshop for health checkup institution personnel in2015.

charge of the structured interview and the primary ultrasound

4) FY 2017

screening of the thyroid.

We strove to develop a partnership with the health checkup

We signed an outsourcing agreement with the RERF and theinstitutions with NFIHO member institutions at the core.

Radiation Effects Association (hereinafter abbreviated as

Despite our efforts, however, blank prefectures still remained"REA"), respectively, and considered outsourcing for FY 2015

(Akita, Yamanashi, Nara, Yamaguchi, Tokushima, andthe extraction of exposure dose records on the emergency

Kagawa). Another challenge was low checkup participation

workers and the verification of the consistency of exposure dose

rates due to poor transportation access in some prefectures. We

records.

redoubled our efforts for further expansion of the network of3) FY 2016

research partner institutions.

In FY 2016, the focus was placed on the development of theclinical survey implementation system and the encouragement

Hosting of meetingsa) Hosting of the RC Meetingof the study target population to participate in this study.

After explanations were made on the questionnaire for use in

Assistance was provided for each Subcommittee to start theirhealth checkups and the standard operating procedures forstudy full scale.

interviews and other related tasks, a question-and-answer

As an effort to further develop the clinical survey
implementation system, a preliminary meeting was held for thesession was held.
b) Thyroid Ultrasound Scan Training Workshop

persons in charge of this epidemiological study (Research

Based on the anatomical and physiological explanations on

Coordinators, hereinafter abbreviated as "RCs"), who were

the thyroid, ultrasound scan techniques for various diseases

mainly nursing professionals, and each appointed by theirwere explained. Then, hands-on training was provided throughrespective health checkup institutions. An inquiry handlingultrasound scan group learning for disease/case exercises. Thissystem for handling various inquiries from research partnertraining workshop is held as necessary on such occasions as the(health checkup) institutions and a health checkup scheduling

replacement of the person in charge at any institution or thesystem for making checkup appointments on the Web wereparticipation of a new member.

introduced as application systems for the information networkc) Practical training workshop on structured interviews related

system. We were finally ready to start centralized sample testing,to psychological impact surveys

which had been a pending matter since the start of this Research

Lectures and computer-based role-playing training were

Project. On December 1, we started a long-term integrated andprovided for the trainees to learn the standard testing method ofstandardized operation of health examining methods practiced

the WHO Structured Interview. This training workshop is also

at all the health checkup institutions.

held as the need arises and has been held an average of once or

As an effort to encourage the study target population totwice per year.

participate in this study, a second letter was sent out to thoseIn accordance with the outsourcing agreement with REA, thewho in FY2015 had expressed by letter their intention to

information of 1,414 individuals each with an identity matchingparticipate, but had failed to be accepted by the institution ofan emergency worker having given written consent was

their preference to take health checkup at. Encouragement ofprovided from the database of the "Radiation Exposure DoseTEPCO employees to take health checkups was started, which

Registration System for Workers Engaged in Decontamination

had been postponed during their internal discussions on theWork."

details of their framework for cooperation in this study. In

5) FY 2018
FY 2018 saw the fruition of the activities up to the previous

September, the first issue of "NEWS Health Checkup News"
was issued as a newsletter for informing all emergency workers

fiscalof the progress made in this study.

examination framework, including tests on individuals having

In accordance with the Agreement with the REA for

year

into

a

functioning

consented to participation in this study.

-8（8）
−100−

comprehensive

healthWhat was newly started in FY 2018 was the outsourcing ofother four facilities) expressed their intention of researchhealth checkup appointment coordination tasks, which had been

cooperation. After some subsequent shuffling in and out, thea pending matter since the start of this Research Proposal. This

current number stands at 77 facilities (See Table 1). As regards

relieves institutions assigned with a large number of target

the outsourcing of health checkup work to these health checkup

individuals from the burden of making contact with prospective

institutions, the items to be checked/tested in the healthexaminees for the adjustment of the health checkup schedule.

checkup/test, and associated matters such as cost and results

Whether to use this proxy service is left at the discretion of eachreporting method were agreed upon in accordance withinstitution, because situations may significantly vary depending

individual agreements with the NFIHO and partner institutions.

on the health checkup institution.

The RERF entered into a package-deal agreement with the

The events held as regular activities of the Headquarters for

NFIHO to outsource all health checkup-related formalities,

FY 2018 are as follows: the eighth meeting of the Operationalbilling of costs and expenses, and other clerical tasks to theCommittee in Tokyo on September 6 (Thu), 2018; the 5th

NFIHO.

session of the Study Group Meeting scheduled to convene in

These 70-odd health checkup institutions are expected toTokyo on March 12 (Tue), 2019; and the 5th session of the RC

make periodic contact with each target individual over the

Meeting in Tokyo on June 28 (Thu), 2018. Besides, an extra

coming 30 years or more, to obtain their written consent andsession of RC Meeting was held on June 8 (Fri), 2018

continuously provide services, such as questionnaire form

(Hiroshima) as a workshop for persons in charge from thefilling, history taking and health checkups, in accordance withfollowing three newly joined institutions: General foundationalan established formula. Many emergency workers are, however,juridical person Japan Occupational Hygiene Association

frequent job-hoppers whose residential location frequently(JOHA) Takaido Higashi Health Checkup Clinic, Generalchanges accordingly. When it comes to surveying such target

foundational juridical person Japan Occupational Hygiene

individuals with high mobility between health checkup

Association (JOHA) Nagano Prefectural Branch, and Generalinstitutions, it is essential to standardize health checkup

foundational juridical person Association for Preventive

techniques and maintain test accuracy among health checkup

Medicine of Japan (APMJ) Western Japan Division.

institutions. Most health checkup institutions can only manage

As regards PR activities, posters and flyers were revised, andto spare their tightly limited time available in between their

web pages were upgraded in addition to the issuance of RC

primary duties, such as thorough medical screening, for healthNews and a newsletter (NEWS Health Checkup News) as

checkup tasks. Moreover, the amount or proportion of time

regular activities.

required for research cooperation significantly varies among theContinuing from the preceding fiscal year, we, in accordance

institutions. In other words, it was considered difficult to expectwith the outsourcing agreement with the REA, it was requested

uniform levels of cooperation and work accuracy from all thethat the REA provide the dose record information of anhealth checkup institutions on a long-term basis. Introduced asadditional 4,560 target individuals having submitted written

a strategic solution to this problem was the concept of eachconsent addressed to the name of the Chairperson of the REA.

institution appointing a person in charge of this epidemiologicalThe extraction of the list of appropriate target individuals is

study to develop a cooperation framework under them to suitunderway for delivery in March 2019.

institutional circumstances. This person is called an RC. We

Establishment of a partnership with institutions

requested each institution appoint an RC in charge of this study

willing to conduct health examinations

primarily from among their nursing staff.

When this study started in 2014, the residential locations of

We requested the institutions engage mainly RCs in history

approximately 20,000 emergency workers, who became thetaking, written-consent acquisition, psychological survey

interest of this study, had already been spread across all 47

interviews, and the overall coordination of research-related

prefectures of Japan. Hence, it was critically important totasks, including reporting of health checkup results andestablish a country-wide research implementation organization

dispatching of collected samples. To standardize these tasks andto make contact with each of these study target individuals andimprove the efficiency thereof, we issued the "Guidebook forinvestigate their health condition. So, we called out for research

the Health Checkup Institutions" and have hosted an RC

cooperation to related medical institutions across the country,

Meeting once a year, with full attendance of all RCs, to have thewith a focus on the member institutions of the National

discussions necessary for coordination. At the same time, weFederation of Industrial Health Organizations (hereinafter

have also been issuing a periodical newsletter (RC News) toabbreviated as "NFIHO") organized by health checkup

communicate and share the latest information.

institutions specializing in industrial health services for workers.

The "Guidebook for the Health Checkup Institutions" issued

As a result, 70 facilities (66 NFIHO member institutions andto each RC is carefully designed to allow standardization down

-9（9）
−101−

to detailed procedures. The resulting standardized techniques

nuclear facilities they worked at and the exposure doses they

are supposed to be passed on from a preceding RC to aexperienced. In other words, the REA investigates the types,

succeeding RC. In some cases, however, this intergenerational

characteristics, and other aspects of personal dosimeters andsuccession of techniques was impossible due to unusual

other instruments in current or former use at nuclear power andcircumstances, such as the replacement of the RC due to illness.

associated facilities in Japan. Additionally, taking into

As a precaution against such cases, the Headquarters

consideration the reality of personal dose control and related

implemented a framework for providing RCs with on-the-job

practices at nuclear power business operators, the REA

training. This is indispensable support for RCs from newly

maintains long-term records of exposure doses experienced byjoined research partner institutions. More specifically, RCs areindividual workers. Accordingly, it was planned to obtain theinvited to the Headquarters Secretariat to be briefed on the

exposure doses experienced by emergency workers during theoutline of this study, while observing demonstrations of actual

work. For those with a history of nuclear work before and afterwork, and to undergo on-the-job training in the health checkup

the emergency work, it was planned to receive the provision of

workflow, system operations, and other tasks.

such exposure doses and other information. To realize this, we

Acquisition of basic and related information (long-must first undergo formalities to obtain consent to the provision

term health management system, causes of death,of exposure dose records of emergency workers from theand REA’s doses)

corporate participants in the Radiation Exposure Dose

We, as this study Group, continued with the continuous

Registration System for Workers Engaged in Decontamination

health survey of the target population to analyze and evaluateWork. This is no more than the prerequisite for us to obtain thechanges therein. At the same time, we obtained the following

consent of individual emergency workers to the use of theirrelevant information from related organizations and made theinformation. Under these conditions, the RERF first concluded

obtained radiation exposure information available for use in thisan outsourcing agreement with the REA for the implementation

study to investigate its relevance:of tasks to be described later.

(i) Provision of information, including the latest address and

The external doses indicated by pocket dosimeters worn by

dose information, biological effects information, and detailed

almost all workers during the emergency work are available,

exposure work-related information, through the long-termalong with the effective whole-body doses calculated based

health management system

thereon, from the above-mentioned MHLW Long-Term Health

We were provided with the following information from theManagement Database. Then, as a project for FY 2015, we

healthconsidered how to verify the consistency of the long-term healthmanagement of emergency workers, including the latest address

management system data with REA's exposure dose records.

information based on the annual current status survey:

After this, in the FY 2016 Commissioned Project "Preliminary• Worker information file;

Survey Work for Extracting Records of Exposure Doses• Work/exposure dose information file;Experienced by Emergency Workers," we ran checks against• Daily work/exposure dose information file;

REA's records and identified potential problems for each

• General health checkup information file;individual. In the FY 2017 "Commissioned Work Including the• Ionizing radiation/emergency health checkup information file;

Extraction of Exposure Dose Records of the Emergency• Other test information file;

Workers," with these challenges taken into consideration,

MHLW-developed

databaseforthelong-term• Exposure work-related information relevant to Notification

identity collation was performed of individuals having

No. 1109-1 "Matters Concerning Submission of Exposure

submitted a written consent. Then, we received the provision ofWork-Related Information on Designated Emergency Workers

information of 1,414 individuals, each with an identity(Request)," issued on November 9, 2015, by the Industrial

matching an emergency worker. In FY 2018, we outsourced the

Safety and Health Department, Labour Standards Bureau,

identity collation of the remaining 4,560 individuals having

MHLW;

submitted written consent, and will receive delivery of the• Company Code List;

results in March 2019.

• Emergency Worker List;(iii) Cause-of-death data from the MHLWWe requested that the MHLW extract and provide the• Cataract patient identification numbers;• FY 2016 Cataract Examination Results, etc. (TEPCO).

necessary contents of diagnosed death certificates and death(ii) Radiation Effects Association (REA)

receipts

from

MHLW-possessed

questionnaire-based

REA's Radiation Dose Registration Center (hereinafter

information, so that we could produce demographic statistics

referred to as "Central Registration Center") has a register offor FY 2017 onwards to perform statistical analysis of thethose engaged in emergency work, to record the names of

personal information of target individuals, such as their time of- 10 （ 10 ）−102−

death and cause of death, and determine the relevance between

method. Moreover, this structure may be changed as timeradiation and deaths due to specific diseases. We were thenelapses. Hence, the information processing system must

provided with such information on Japanese nationals who diedflexibly accommodate changes that may occur.

during the period from March 2011 to December 2016. From

Immediately after the start of this study, consultation started

now on, the name, sex, and birth date of each emergency worker

on the basic concept of system development. In FY 2015, thewhose death is confirmed shall be collated with thefundamental part of the dedicated information network systemdemographic statistics to collect the cause-of-death information

featuring robust confidentiality was completed, followed by theof those deceased. Moreover, we intend to use the Cancer

completion of the application systems, such as a transmission

Registration System to receive the provision of information on

and reception system, an inquiry handling system, a healthcancer incidence among the target population.

checkup scheduling system in FY 2016. On December 1, 2016,

3) Information processing system and information control

the current system became operational.

This study includes in its scope more than 5,000 enterprises

As explained in the next Section, all basic data obtained

to which the survey target individuals belonged at the time ofthrough this study will be stored in the data server installed in

the emergency work. In addition, the residential locations of thethe supervising institution. This data server has the function oftarget individuals are spread across all prefectures. Accordingly,

automatically creating backup copies as a precaution against

health checkups and other investigatory tasks, such as history

unexpected failure. In addition, all possible measures have been

taking, are consigned to more than 70 research partner

taken to protect the basic data: for example, backup copies

institutions located across the country. There is a clinical testing

periodically created are stored in external storage. Although the

body that undertakes the analysis of all the samples for analysis.

data server is maintained by the System, there are many

There is also a proxy service provider for checkup appointment

connections to the network, and the risk of hacking attacks fromscheduling. Because a wide range of data is handled by such aoutside is correspondingly high. Hence, all possible measureslarge research organization stretched all over the country

are taken to ensure security.

throughout the rest of the target population's life, an information

All the health checkup institutions must submit test datasystem is required for assistance in all practical aspects of study

obtained through health checkups to the RERF. Therefore, all

implementation, including management and analysis ofinstitutions have dedicated terminals installed that arecollected data suitable to conduct continuous surveys.

connected via mobile routers to the dedicated network. To log

Therefore, by outsourcing to specialist contractors, we built ain to this system, the operator must use an ID and password

dedicated basic database for this study, a network system

issued to a pre-registered user.

connecting all the footholds, and various application systems,

Considering the diverse specialties of the personnel using theand outsourced the operation and support of these systems.

System, efforts were made to enhance the usability of the

While more than one organization is involved here, there areinformation network system as much as possible. One of these

preparatory tasks to be completed for each checkup examineeefforts is the development of application systems such as theahead of the health checkup date. Such tasks include: making"inquiry handling system" for handling various inquiries fromhealth checkup appointments; dispatching consent forms andhealth checkup institutions, and the "health checkup schedulingquestionnaire forms; calculating the travel fares to and from thesystem" for making checkup appointments on the Web.

health checkup institutions; and procuring materials andAccordingly, the RC Meeting provided explanation on theequipment including blood collection tubes necessary for the

standard method of data exchange through the dedicated system,

collection and transportation of blood or urine samples. On top

as well as how to apply the information available from theof these, cases are not rare where changes occur in the middle.

health checkup scheduling system to the billing of costs andThis system is intended to handle personally identifiable

expenses. In the FY 2018 session of the RC Meeting,information and, as such, must provide a high level of

discussions were had on matters such as better approaches tomaintainability of its information management function.

deal with individual study participants.

Furthermore, there are many Co-Investigators and Research

Establishment and management of the tasks of the

Collaborators involved. Some of them have to collect their

Supervising Research Institution

target individuals' data from six joint research institutions

In the RERF (Hiroshima) Clinical Research Department aslocated in different locations. In addition, some of the data to be

the Supervising Research Institution, the "Nuclear Emergency

provided may have to undergo collation with certain basic data

Workers Health Study Office" (hereinafter abbreviated as

items before acceptance. In a system with such a cross-"NEWS") was organized to provide a secretariat function andsectionally complicated structure that assumes changes overestablish a research support framework for carrying out thetime, study information must be sent and received by a secure

following tasks:- 11 （ 11 ）
−103−

(i)

Request for the internal review of the Research Protocol

application for the FY 2014 Industrial Disease Clinical

The Basic Research Proposal part of the "EpidemiologicalResearch Grants to invite applications for grant for an

Study Targeting Nuclear Emergency Workers at the TEPCO

Epidemiological Study on Health Effects on Radiation Workers

Fukushima Daiichi Nuclear Power Plant" was approved as

as an area of radiation effects studies. The Notice said that the

Research Protocol (RP6-15) in accordance with the research

amount for the initial year would be approximately ¥100 million,

review and approval rules of the RERF.

the research budget per year would range from ¥300 million toThis study was reviewed for ethical aspects as follows: the¥500 million, and the grant period would be extended by five204th Joint Session of the RERF Human Investigation

years at a time. One of the requirements for research proposals

Committee (HIC) and Ethics Committee for Genetic Research

for the application was for them to build on the(ECGR) was held on December 11, 2014, to review the method

recommendations by the "Report of the Expert Meeting onof obtaining the list of target individuals from the MHLW long-

Epidemiological Studies Targeting Emergency Workers at theterm health management database, and also to review the

TEPCO Fukushima Daiichi Nuclear Power Plant (June 4,

content of the letter sent to inform the survey target population2014)." It was additionally required for the implementation ofof 20,000 persons about this study. Then on January 21, 2015,

the study to ensure continuity from an existing study funded by

the 205th Joint Session reviewed the fundamental part of the

MHLW Grant-In-Aid, and cooperation with the co-authoring

Research Protocol and the content of the letter of consent toinvestigators of that study. Furthermore, as regards the post-

participation in the preliminary survey before sending it to theadoption research system, it was suggested to consult with thetarget individuals living in Fukushima Prefecture. On January

MHLW as a method of guaranteed research outcomes.
On August 29, 2014, Toshiteru Okubo (then RERF

23, 2015, approval was granted. Since then until today,
information letters to the survey target population, the consent

Chairman) was the representative of the Supervising Researchform and written explanation thereof, and other documents have

Institution and submitted, as the Principal Investigator of thisbeen reviewed and approved for additions and modifications as

study

follows:"Epidemiological Study Targeting Nuclear Emergency Workers

theResearch

Protocol

for

the

study

theme

• December 11, 2014 (204th HIC/ECGR);at the TEPCO Fukushima Daiichi Nuclear Power Plant" in• January 21, 2015 (205th HIC/ECGR) / Approved on January

accordance with23, 2015;

Application. On October 21 of the same year, as the result of a

• May 21, 2015 (208th HIC full board review) / Approved onhearing and a review, Okubo was notified of the standard

June 11, 2015;

amount to be granted from the National Treasury (¥89,440,000).

the applicable Guidelines forOpen• July 29, 2015 (210th HIC expedited review);

The study period of the initial accounting year was from• August 26, 2015 (212th HIC/ECGR expedited review) /October 15, 2014, to March 31, 2015. As a result of subsequent

Approved on September 11, 2015;

consultation with the MHLW, a research organization was• July 13, 2016 (FY 2016 5th IRB expedited review) / Approved

established, followed by submission of the Application for

on July 19, 2016;

Research Grant Delivery with a due date of November 14 of the• August 15, 2016(FY 2016 7th IRB expedited review) /same year.
Then from the second year onwards, an Application forApproved on August 16, 2016;• October 12, 2016(FY 2016 10th expedited review) / Approved

Continued Research has been filed to undergo an interimon November 2, 2016;

evaluation as required. Every year up until FY 2018, the fifth• May 18, 2017 (IRB full board review) / Approved on July 11,

year, an annual Research Implementation Plan has been

2017;

continually presented.

• September 4, 2017 / September 14, 2017; and• Preparation and distribution of the Research Reports
The Annual Research Reports for the years from FY 2014 to• April 18, 2018 (full board review) / April 23, 2018.
(ii) Application to MHLW for Research Grant Delivery and

FY 2017 each consist of a Comprehensive Research Report andProject Performance Report to MHLW

Working-Group Research Reports. The manuscripts were• Application for Continued Research and Formal Application

submitted from the WG Investigators and then compiled by thefor Grant Delivery

Secretariat for outsourced proofreading and printing. The total[Background of application for a research grant for the initial

number of pages of the Annual Research Reports in book form

year]

for FY 2014, FY 2015, FY 2016, and FY 2017 were 97, 172,
Compensation

213, and 229, respectively. These were submitted to the MHLW

Administration Division, Worker’s Compensation Department,at the end of March of every fiscal year and distributed to the

Labour Standards Bureau, MHLW, issued a notice of open

WG Investigators, all the research-partner health checkup

On

July

31,

2014,

the

Worker’s- 12 （ 12 ）−104−

institutions across the country, public libraries, and other

the Administrative and Accounting Department to facilitate

audiences.

smooth execution of health checkups for this study. To conduct(iii) Hosting of Meetings based on the Research Operations

health checkups with the same level of quality across the

Frameworkcountry, the RC Meeting convened once each year as follows in• Hosting of Meetings of the Operational Committee
An

Operational

Committee

consisting oforder to share important information and handle various issues,
key

Co-

such as improvement requests and opinions received from

Investigators was established as the decision-making body ofindividual institutions:this study Group to deliberate on, among other agenda, the

1st session of RC Meeting: March 14 (Sat.), 2015, Tokyo;

Research Proposal and issues concerning the implementation of

2nd session of RC Meeting: August 18 (Tue.), 2015, Tokyo;

this study.

3rd session of RC Meeting: June 18 (Sat.), 2016, Tokyo;

1st meeting of Operational Committee: December 9 (Tue.),

4th session of RC Meeting: June 21 (Wed.), 2017, Tokyo; and2014, Tokyo;

5th session of RC Meeting: June 28 (Thu.), 2018, Tokyo.

2nd meeting of Operational Committee: January 8 (Thu.), 2015,

In FY 2017 and FY 2018, the RERF (Hiroshima) provided an

Tokyo;

orientation for the following newly joined research-partner

3rd meeting of Operational Committee: April 30 (Thu.), 2015,

health checkup institutions in order to explain to them theTokyo;

outline of this study and the health checkup workflow, as well

4th meeting of Operational Committee: August 17 (Mon.), 2015,

as to demonstrate how to use health checkup-related systems:

Tokyo;

May 26 (Fri.), 2017, Hiroshima

5th meeting of Operational Committee: December 15 (Wed.),General foundational juridical person Kimitsu Health Center;

2015, Tokyo;

Seirei Sakura Citizen Hospital, Social welfare juridical

6th meeting of Operational Committee: November 1 (Tue.),

person Seirei Social Welfare Community; and2016, Tokyo;

Medical juridical person Sugai Clinic;

7th meeting of Operational Committee: August 30 (Wed.), 2017,

June 8 (Fri.), 2018, Hiroshima

Tokyo; andGeneral foundational juridical person Japan Occupational

8th meeting of Operational Committee: September 6 (Thu.),

Hygiene Association (JOHA) Takaido Higashi Health Checkup

2018, Tokyo.

Clinic;• Hosting of Study Group Meetings

General foundational juridical person Japan Occupational

A Study Group Meeting was held once a year to provide eachHygiene Association (JOHA) Nagano Prefectural Branch; andStudy Group with an opportunity to report on their study. All

General foundational juridical person Association for

the Co-Investigators and Research Collaborators werePreventive Medicine of Japan (APMJ) Western Japan Division.

convened so they could be updated on the status of activities at

In addition, "RC News" was issued as necessary to share

the headquarters of the Supervising Research Institution and theinformation, including the status of progress made in this study,

status of progress made by each of the other Subcommittees.

with the health checkup institutions. Meanwhile, annual

1st session of Study Group Meeting: November 14 (Fri.), 2014,

updates were made to the basic information of the RC contacts

Tokyo;of all the health checkup institutions once a year.

2nd session of Study Group Meeting: March 12 (Sat.), 2016,(iv) Operation of remote conferences with individual

Kitakyushu;

Subcommittees (WG Investigators/Research Collaborators) and3rd session of Study Group Meeting: March 9 (Thu.), 2017,

implementation of adopted resolutions
In cooperation with the Co-Investigators of the respective

Tokyo;
4th session of Study Group Meeting: March 15 (Thu.), 2018,

Subcommittees in accordance with Research Proposals, theTokyo; andtarget individuals necessary for the studies under the

5th session of Study Group Meeting: March 12 (Tue.), 2019,

Subcommittees were identified followed by the provision of theTokyo.

following clerical assistance including the preparation of• Research Coordinator (RC) Meeting

various information letters, address printing thereof, andEach of the 77 research-partner health checkup institutions
across the country has appointed one or more RCs, whose

dispatch thereof:• Clinical Survey Subcommittee
A system was established for ensuring the accuracy ofspecialty is basically medical or public health nursing. At theirrespective institutions, these RCs have the function of making

clinicaladjustments with the Appointment Scheduling Department, thetransaction tasks, including: the process from the printing of the

Test Department, the Information Processing Department, and"Questionnaire Form on Health and Lifestyle Habits" to data

- 13 （ 13 ）−105−

investigations

toperform

variousinformation

entry; various inquiries to health checkup institutions; collation

through the application filed in FY 2017 to the MHLW forof the questionnaire and test results with the consent

approval of using demographic survey information outside theinformation; preparation and transmission of hepatitis virus

intended purpose.

test/thyroid function test results reports; sample transportation;3) Selection of the contractor for the development of a system

receipt of test results; and control of stored test samples.

for extracting the cause-of-death data on the target individuals• Thyroid Cancer Survey Subcommitteeof the relevant Study; and preparation of the reference materials

Qualification registration tasks for participants in the Thyroidfor bidders.

Ultrasound Technician Training Workshop and issuance of the4) In FY 2018, an application for approval of a change in theWorkshop Handbook: A skill evaluation-and-registration

procedures for using demographic survey information outside

system was introduced to improve and control the accuracy of

the intended purpose was filed to the MHLW to suit the purpose

the thyroid ultrasound technicians engaged in the Studyof rational system development; and the approval was granted.

concerned. The Secretariat took on this technician registration• Psychological Impact Survey Subcommittee

work and issued copies of the Health Handbook to the1) Outsourcing of the preparation and printing of psychological

technicians from research-partner health checkup institutions

impact study questionnaire forms, optical answer sheets, andinvolved in the Training Workshop.

envelopes.

1) Issuance of system login IDs and passwords for the "Thyroid2) Dispatch of questionnaires and answer sheets to the health

Ultrasound Scan Information System" for the Accuracy Control

checkup institutions.

Committee and health checkup institutions3) Control of answer sheets received from the target population

2) Uploading of past scan test data to the "Thyroid Ultrasound(by means of personal identification numbers), request for

Scan Information System"computerization of information scanned from optical answer

3) Tasks for ensuring the continuity from the existing Study:

sheets, and acceptance of data

• Ethics review of the Research Protocol for transferring the4) Provision of data linking structured interview results withinformation collected during FY 2013 Health and Labour

consent information and relevant factors to the Subcommittee,

Sciences Research Grant Special Research Proposal "Research

besides anonymized information scanned from optical answer

on Thyroid Gland Examinations, etc., of Workers at the TEPCO

sheets

Fukushima Daiichi Nuclear Power Plant" for use in this study;• Cataract Working Group: Printing of the checkup cards for use

receipt and storage of information in accordance with theat ophthalmological clinics all over the country cooperating inreview results; dispatch of documents for obtaining consent forthe cataract study; collection and organization of consent forms,

personal data use to target individuals; sorting and organization

findings/evaluation results, and bills and other reply documentsof return mail; and handling of the data sampling request fromfrom clinics; data transmission of the Subcommittee; andthe Subcommittee.

checking of cataract examination bills and forwarding thereof• In accordance with the plan for collecting TEPCO-heldto the Study Group.

thyroid-related information, a consent acquisition form and a(v) Management of personally identifiable information on target

reminder were sent to target individuals, followed by the receipt

individuals (printed materials and electronic information)and storage of thyroid-related information from TEPCO and byPrinted materials, such as participation intention survey

the provision of anonymized personal data to the Subcommittee.

sheets, consent forms, and questionnaire sheets, are received by• Dose Assessment Subcommittee

the Secretariat via health checkup institutions and checked for

A sealed letter requesting dose information was sent to thecontent. Printed materials containing any imperfections and/or

emergency workers considered to be target individuals of theinaccuracies are completed or corrected by checking with the

Fukushima Health Management Survey, followed by the entry

relevant parties, and the resulting final information is enteredand compilation of received data, and by the handling of

into the System. After this, the printed materials are filed ininquiries from the target individuals who received the letter.

person-specific master files for retention in storage.

After the completion of data compilation, anonymized data for• Acceptance and checking of health checkup results (printed

research and the aggregate results will be provided to themedia), such as questionnaire answer sheets and consent forms,

Subcommittee.

from the health checkup institutions• Cause-of-Death/Cancer Incidence Survey Subcommittee•

1) Provision of data, including the number of checkup

questionnaires, other questionnaires, consent forms, and otherexaminees, for annual reports.

printed media into the System

2) Retention of the death certificate-based and death receipt-• Collation of the name and residential location data of target

based information for FY2011 to FY2015 that was received

individuals with the results of the Current Status Survey- 14 （ 14 ）
−106−

Entry

of

informationfromparticipation

intention• Data updating authorized by the authority of the master update

receipts, etc.; dispatch of health checkup-use materials such assystem administrator

consent forms(vi) Framework building and health checkup support tasks for• Receipt of health checkup results: receipt and check of data by

research-partner health checkup institutions

collation with consent information; and inquiries in case of

To provide a safe margin of health checkup capacity for target

imperfections or inaccuracies

individuals, efforts were made to increase the number of partner• Preparation and updating of the Guidelines for TEPCO's

health checkup institutions, mainly from among NFIHO

Alternative Health Checkup: An explanatory document wasmember institutions, in blank prefectures with no research-

prepared, which contained the health checkup schedule, the test

partner health checkup institutions or in prefectures with anitems to be added depending on the age, type of work engagedexcessive number of target individuals. As a result, the numberin, etc., and the methods of reporting.

increased from the original 70 to 77 in FY 2018.

• "RC News" was issued as necessary to share information,

The "Guidebook for the Health Checkup Institutions" wasincluding the status of progress made in this study, with thecompiled to standardize health checkups at the research-partner

health checkup institutions. The basic information of the RC

health checkup institutions. The Guidebook consists of thecontacts of all the health checkup institutions was condensed"Guide for epidemiological research partner institutions" andinto a list and updated once a year.

the operator's manual for each system, in addition to the• Adjustments were made with institutions preferred by target"Standard Operating Procedure for Clerical Work Processing

individuals to determine the number of health checkups

for the Epidemiological Study Project" based on the contractual

acceptable for each institution. For institutions with anrelationship with the NFIHO. Whenever any revision is madeexcessive number of health checkup appointments, the backlog

to files, copies of new files are distributed to the health checkupof examinees was split and diverted to other institutions.

institutions, and the corresponding electronic files are also

• Hepatitis virus test/thyroid function test results reports arerevised. Accordingly, a framework was established for healthprepared and then transferred via a file exchange system forcheckup institutions to download these documents from theinclusion in the checkup results to be sent from the health"file transmission and reception system" whenever required to.

checkup institutions to checkup examinees.

Requests were made for improvements on the part of theresearch-partner health checkup institutions, such as health(vii) Framework building for centralized testing and the mainfunctions of the Secretariat

checkup quota enhancement and System usage enhancement.

As explained above in "Research Methodology (4) Analysis

At the same time, proposals and adjustments were made to solveof test samples and preservation of stored samples," thevarious issues. One such example is the health checkup

prerequisite for the centralization of testing tasks to Kotobiken

appointment scheduling proxy service that became operational

was a method of adjusting test results deliveries to the healthin FY 2018. In the case of ordinary health checkups, contacts

checkup institutions and the RERF. At first, complaints were

for appointments come in from the checkup examinees’ side. In

received from the health checkup institutions saying, forthe case of this study, however, contacts must be made by theexample, that they could not make evaluations due to thehealth checkup institutions. Phone calls very often end up goingdiscrepancy between their reference ranges for clinical testunanswered, cumulatively causing a heavy burden on the healthevaluation and those reported by Kotobiken. It was agreed thatcheckup institutions. Accordingly, for the sake of some health

Kotobiken should match their reference range to that of eachcheckup institutions hoping to be relieved of this burden, it was

institution. At the same time, it was agreed that Kotobiken

decided to outsource this task to specialist contractors. Thisshould be provided with data formatted to suit the system on thedecision led to the smooth processing of backlogs ofpart of each health checkup institution. Since when all test

appointment scheduling jobs. Other health checkup support

samples began to be centrally sent to Kotobiken, a sample

tasks are as follows:

delivery form for the health checkup scheduling system has• Liaison tasks: various types of notification, requests forbeen used in collation work to ensure that the current day's

provision of missing data/materials, handling of various

batches of samples are processed without fail. Leasing

inquiries (questions, complaints, etc., received from target

centrifuge machines to some health checkup institutions notindividuals before, during, or after their health checkup are

equipped with their own has also started. Following theeventually entered by each health checkup institution into thecentralization of tests, it has become an important task to"Inquiry Handling System" and then responded to by theprevent various problems such as hemolysis, missing samples,

Secretariat.)and reports of panic values: In practice, incidents and accidents• Courier tasks: calculation of honoraria/travel expenses

in testing tasks have been dealt with in accordance with apayable to target individuals; preparation and dispatch oftroubleshooting manual and recurrence prevention measures- 15 （ 15 ）−107−

have been verified.

responsibilities of the Headquarters Secretariat. The main tasks

One of the tests thus standardized is thyroid ultrasoundinvolved are as listed below:

scanning. On account of understaffing, some health checkup• The purposes of expenditures for research implementation;

institutions failed to cooperate in standard thyroid ultrasoundand awareness-raising for efficient use of human resources

scanning, posing a problem for the future.

► Preparation of written justifications required to complete(viii) Publicity activities targeted at emergency workers

formalities for commodity purchasing, outsourcing, staff

The following PR activities were deployed to call out forrecruitment, etc.

participation and cooperation in this study:► Negotiations for effective allocation of human resources to• Phone calls requesting for cooperation (In FY-2016 calls wererelated in-house departments

made to confirm the receipt of the application form for► Explanations at Review Commission, etc., and presentation

participation and to request cooperation; In FY-2018 calls wereto Board Members

made to encourage high-dose target individuals to take health• Outsourcing agreement: order placement; preparation of bid

checkup.)

specifications; request for estimation; request for a legal check• Development and updating of the website (which acceptsof written agreement and correction thereof; and retention of theconsent forms and applications for health checkup; at the same

written agreement

time, however, the task of asking for a signature on the consent• Scrutinizing and inquiring about outsourced service

form still persists.)

performance reports from the NFIHO• Preparation and distribution of posters and flyers• Scrutinizing and inquiring about health checkup participation• Production and delivery of NEWS Health Checkup News

rate reports from research-partner health checkup institutions;• Re-dispatch of information to alternative addresses of persons• Accounting-related documentation, including documentation

unknown at the address used

for allocating shares of expenses to each Study Group• Preparation and dispatch of additional letters requesting• Checking test data report results received and amounts billedcooperation from non-respondents

from Kotobiken• Production of listing advertisements, landing pages, PR videos,• Checking health checkup participation rate reports from healthand banner advertisements

checkup institutions all over the country and preparing requests• Open house at RERF facilities as a publicity activity of thisfor payment

study• Reminding health checkup institutions of submission of(ix) Encouragement of in-house (TEPCO) alternative healthmonth-end due data not delivered yet

checkup; and ex post facto support• Order placement for health checkup-use materials, such as• Every spring since 2017, TEPCO has set up consultationconsent forms and questionnaire forms; requisitioning andbooths during the regular in-house health checkup to handle

inventory control of other items such as consumables, furniture

inquiries from their employees regarding matters such as

and fixtures, etc.

application for participation.

• Receipt and payment bookkeeping and other accounting tasks• Extraction of the names of target individuals by status, such as• Internal formalities such as requisitioning payment of postage,

prospective health checkup examinee, participation refuser, or

courier service bills, phone bills;

person unknown at the address used, from TEPCO's alternative• Handling of inquiries from MHLW Workers' Compensation

health checkup

Administration Division, and other related tasks• The categorical attributes of prospective examinees of• Dealing with internal audit, MHLW accounting audit, and on-

TEPCO's alternative health checkup, such as current

site investigation by the Board of Audit of Japandepartmental affiliation or decontamination work history, werechecked with TEPCO so that they would be flagged in the[Summaries of Studies by Individual Subcommittees]

health checkup scheduling system to allow the viewing of theClinical Survey Subcommittee (Clinical I)
Throughout the year, the Clinical Survey Subcommittee

additional test items required to be made known to healthcheckup institutions.

obtained informed consent from voluntary study participants,• Data extraction tasks were outsourced to reflect healthprovided them with health checkups for grasping their healthcheckup results in TEPCO's in-house health management

condition as the baseline data for follow-up studies, andsystem.

conducted clinical studies including the storage of biological(x) RERF internal formalities and accounting paperwork

test samples.

The appropriate and effective use and reporting of theQuestionnaire survey of health and lifestyle habits, various

expenses for this grant-funded Study is one of thetest results, and the status of acquisition of consent to- 16 （ 16 ）−108−

cooperation in this study

ignored, as they provide confounding factors. The long-term

Written consent consisted of the following items: 1) study

effect factors to be covered may include: nationality, area ofobjective, 2) study period; 3) study target population; 4) healthresidence, income, educational level, and serious social

effects to be studied; 5) test items; 6) participation cost; 7)experience encountered, among others. The important factors

access to and disclosure of Research Proposal; 8) protection of

from a short-term perspective include the time and period of

personally identifiable information; 9) freedom to opt in and out

engagement in the emergency work, and the status as anof this study; 10) benefits and disadvantages of participation in

employee.

this study; 11) reporting of health checkup results andpublication of research outcomes; 12) Intellectual property

Cataract Working Grouprights generated from this study; and 13) conflicts of interest

For the current TEPCO employees exposed to a dose of 50

arising from this study. So far, the consent rate for each of thesemSv or more (approximately 700 persons), a joint cataract study

items has been 99.9% or more.

has been conducted every year at three locations, the Fukushima

The age-adjusted proportion of obese individuals (BMI 25

Nuclear Power Plant (Daiichi and Daini), Kashiwazaki-Kariwa,

Kg/m2 or more) among the past health checkup examinees was

and Tokyo Headquarters, as a joint survey with the Department

35.6%, showing a slightly higher propensity to obesity thanof Ophthalmology of Keio University School of Medicine.

shown by the male obesity rate in the National Health and

For this study, 3,685 individuals exposed to 20 mSv or more

Nutrition Survey. The age-adjusted average systolic blood

were selected as the target individuals of the cataract study.

pressure was 123.6 mmHg and lower than among the general

With cooperation from 71 ophthalmological clinics across the

public.

country, the cataract study was started in FY 2018. The

The proportion of habitual smokers was 33.9% and slightly

diagnostic criteria for cataract vary depending on thehigher. The proportion of individuals with a habit of drinking

ophthalmologist. Hence, a Cataract Determination Manual

alcohol once a month or more was 84.2%, which is a proportion

based on the WHO's Criteria was prepared for use in a training

considerably higher than among the general public. Thus, anworkshop held for ophthalmologists from the partner facilities.

overview of the health conditions among the target individuals

In addition, naked-eye determination alone cannot provide

having taken health checkup during the 5-year first phase of thissufficient consistency and reproducibility of diagnosis.

study revealed that they showed some anomalies, such as higher

Therefore, a simplified transillumination camera was built tovalues for several items as compared with the ordinary

enable objective and quantitative evaluation, and was put into

individuals.

use for the eye checkup of TEPCO employees. In FY 2018,
capturing retroillumination images of lenses was started, with

Clinical Survey Subcommittee (Clinical II)

one unit installed in an ophthalmological clinic in Fukushima

For Clinical Survey Subcommittee II to evaluate the healthwith a large population of target individuals. From the next

effects on the emergency workers, social factors, such as

fiscal year and onwards, all facilities will each be installed with

employment and daily-life background, and health control

a camera.

conditions, such as industrial health or medical services

In response to a letter of request in FY 2018, replies haveaccessibility environment must be taken into consideration as

been received as of now from 996 individuals, 703 of whom

confounding and other factors for the evaluation of the effect ofexpressed their willingness to undergo a checkup. Of theseradiation exposure. Accordingly, it was decided to examine inpeople, 217 individuals have completed their checkups.

detail the worksite conditions and social factors specific to theseengaged workers during the period from the time of theThyroid Cancer Survey Subcommittee

emergency work until now, and to question significant ones on

As a result of the thyroid ultrasound scanning conducted in

the occasion of the clinical survey. The methods for this purpose

the survey prior to this study, 425 individuals' worth ofwere considered.

information was received (275 cases in 2014; 333 for in 2015;

The survey results so far showed no significant differences inand 372 for 2016; 980 in total) to continue with the analysis.

health conditions between the types of work engaged in. The

Then, this study considered the thyroid ultrasound scanning"Other" types of work engaged in, however, accounted for the

methodology for the whole emergency workforce, prepared thehighest proportion of 45.5% among the target population.

"Guide to Thyroid Ultrasound Scanning," and held eightHence, it is planned to consider making a finer segmentation ofsessions of Thyroid Ultrasound Scanning Training Workshops

the "'Other types of work engaged in" on the questionnaire.

for engineers on ultrasound scanning procedures, image

In the evaluation of the long-term health effects after

diagnosis methods, and post-test workflow.

engagement in emergency work, social factors must not be- 17 （ 17 ）−109−

By the end of 2017, the number of certified techniciansreached 107 individuals, while that of certified facilities reacheddepression-related evaluations.

49. As of the end of October 2018, 2,424 cases of determination

A phenomenon is known that certain environmental factors

have been completed at Jichi Medical University (final

negatively

determinations: 1,076 A1 cases (44.4%), 966 A2 cases (39.9%),

discrimination, character assassination, slander, and blame-

382 B cases (15.8%), zero C cases (0.0%)). As regards theshifting. The FY 2016 and FY 2018 surveys on 1,572 and 3,000

secondary screening, replies of consent to consignment wereindividuals suggested the relevance of such stigmas with theirreceived from 130 facilities. As of December 2018, 157 reportsage (especially thirty-somethings), educational backgroundstigmatize

certaingroupsasobjectsofon checkup examinees have been received. The guidelines for(high school graduates), long work period, mental healththe secondary thyroid scanning and after shall be the same as(psychological distress/post-traumatic stress symptoms), andthose for the primary scanning. It shall be sufficiently explained

insomnia symptoms. The stigma scale showed a correlationthat thyroid scanning will result in the need of detailed

with psychological distress/post-traumatic stress symptoms andscreening for a certain proportion of the target individuals, a

insomnia. Drinking habits, with which no correlation had beencertain proportion of whom will be found in need of treatment.

found, showed correlation with more than half of the questions
asked.

Psychological Impact Survey Subcommittee
For the evaluation of psychological impact evaluation in thisCause-of-Death/Cancer Incidence Survey Subcommittee

Survey, a questionnaire survey and an interview survey wereused side by side.

Of the health checkup examinees, 90% or more expressed
their consent regarding the collection of cause-of-death data andA questionnaire prepared in FY 2014 was used to investigate

cancer incidence data. Reportedly, of the survey target

the relevance between the mental health level of nuclear

population, 269 individuals died. For a cause-of-death survey,

emergency workers and major stress-related factors. A request

an application for collation with Demographic Statistics

for cooperation in the questionnaire survey was made to health

Information was filed to the MHLW, followed by receipt ofcheckup examinees. To those who consented, copies of theapproval dated November 2, 2017. Following the receipt of thequestionnaire form were issued with a request for a reply byprovision of country-wide data based on death receipts, amail. The 3,000 individuals who sent back their answers bymethod of collation with the list of target individuals began toJanuary 31, 2018, showed no apparent differences in mental

be considered. The challenge to cancer incidence data collection

health levels from those from the previous study. These mental

is how to collect target individuals' addresses as of the time ofhealth levels and PTSD symptoms (evaluated based on IES-R

their cancer diagnosis.

scores) showed a significant relevance with stress-related
factors, including stigmas, life events, social assistance with

Radiobiological Study Working Groupdaily life, some stress-coping behaviors, the sense of self-

When the effects of low-dose exposures were evaluated based

esteem, and the level of satisfaction with work and home life. It

on radio-adaptive responses, mice exposed to 3 Gy after 0.02-

was also suggested that the support from superiors had

Gy pre-exposure showed a p53-dependent extension of life assignificance in the case of long-term emergency work.

compared with those exposed only to 3 Gy. This difference,

For the interview survey, use was made of the depression

along with others, including one observed in a miRNA

module of the computer-assisted personal interviewing (CAPI)

expression analysis, revealed that large individual differencesin the WHO's Comprehensive International Diagnostic

exist among radio-carcinogenic miRNAs. Additionally, EML4-

Interview (CIDI). From among the 1,380 individuals

ALK fusion genes frequently detected in thyroid papillaryinterviewed by the end of January 2018, six persons (0.4%)

carcinoma in atomic bomb survivors are detected dependent on(most recent one month), 30 (2.2%) (most recent 12 months),

the increase in exposure dose (0, 0.2, 1, and 5 Gy), and hence

and 93 (6.7%) (lifelong) were determined to have "major

may provide a useful diagnostic biomarker. When urinary 8-

depression disorders" as per the DSM-IV, while four persons

hydroxydeoxyguanosine (8-OHdG) samples taken from

(0.3%) (most recent one month), 19 (1.4%) (most recent 12

workers were measured to evaluate radiation-induced oxidative

months), and 52 (3.8%) (lifelong) were determined to havestress, slightly higher values were obtained, suggesting the need"severe depressive episodes without psychotic symptoms" as

to investigate the effects of low-dose exposures.

per the ICD-10. Additionally, the evaluation results as per K6(evaluation scale for depression and anxiety disorders) from theDose Assessment Subcommittee
Severalquestionnaire survey conducted at the same time showed a

years

of

whole-bodycounter

measurement

moderate level of relevancy to the results of this structured

confirmed that the change in the in-vivo residual amount ofinterview method, thereby suggesting the effectiveness of K6 inradioactive Cs is similar to that of the biokinetic model- 18 （ 18 ）−110−

presented by the International Committee of Radiation

identified, including: insufficient response capacity of theProtection

taken

health checkup institutions; or geographical difficulties for

immediately after the accident were verified to have aemergency workers living too far from research partner

sufficiently high measurement accuracy, even with the subjects'

institutions to take a health checkup. First and foremost,

locational uncertainty taken into consideration; on the otherpartnerships with additional partner institutions must be

hand, it was suggested that the individual differences in theestablished in areas with a fast-growing waiting list. A change

shape of the thyroid need to be reflected in internal exposure

should be made from the current strategies for solicitation ofdose evaluations.

cooperation.

(ICRP).

The

thyroid

measurements

As regards the analysis method for I-129, the iodineThis report evaluated the baseline health conditions of theseparation procedure was optimized, thereby providing theJanuary 2016-to-October 2018 health checkup examinees, whoprospects for analysis of the actual urine test sample. Thisaccounted for the majority of the follow-up population of thisSubcommittee established a tricolor FISH-based retrospective

study. As a result, characteristic results were obtained. Obesity

dosimetry technique, contributing to the preparation of ISO

is known to have relevance to various lifestyle-related illnesses,

procedural manual "ISO/FDIS 24006" as a P-member of thesuchInternational Standards Organization (ISO) Working Group 18.

hyperuricemia. The proportion of obese individuals among the

Additionally, an automated image analysis software platform

male checkup examinees after age adjustment by the same

was developed for the technique. In FY 2018, from 62

reference population as in the National Health and Nutritionindividuals who took health checkups at health checkup

Survey was 35.6% and slightly higher than in the results of theinstitutions in Fukushima Prefecture from October to December,

National Health and Nutrition Survey. It is considered necessary,

blood samples were experimentally taken with their consent andfrom now onwards, that obesity-related test items and disease

are currently under chromosome analysis.

occurrences be monitored with close attention. The averageasdiabetes,

hypertension,

dyslipidemia,

and

For the review of the dose assessment for the whole

systolic blood pressure among the male checkup examinees

emergency workforce, a database for storing the information

after age-adjustment by the National Health and Nutrition

necessary therefor is under development and construction, but

Survey was 123.6 mmHg, while the proportion of individuals

will take some time before completion.

with a systolic blood pressure of 140 mm Hg or more was
14.7%: both indicators were low.

D. Discussions

The male prevalence of atrial fibrillation increased with age

The results of the encouragement to participate in this study

when compared with an epidemiological survey by the Japaneseare as follows for the period from the start of the Study to

Circulation Society. Considering that this study is a long-term

October 31, 2018: of the study target population of 19,808

follow-up study, we believe that considerations should be given

individuals, 7,270 (36.7%) showed interest in participation

to collecting and retaining cardiogram records, centralizing(6,656 agreed to take health checkup; 614 agreed to participate

determinations, and actively using archived materials forin other studies); 3,334 (16.8%) declined participation; 6,976

comparative(35.2%) returned no response; 1,828 (9.2%) were addressees

determinations and findings at each research partner institution.

unknown at the address used; 254 (1.3%) were deceased; andBlood biochemical tests detected no items with extreme bias.

146 (0.7%) were unaccountable for due to other reasons. In light

Biochemical tests found that the proportion of individuals withof the Study objectives, this situation cannot be said to bean age-adjusted total cholesterol level of 240 mg/dL or moresatisfactory. To increase the future study target population, it isamong the male checkup examinees was 14.8% and theirnecessary to reduce non-respondents and to urge participation

average value of non-HDL-cholesterol was 146.2 mg/dL: bothrefusers to reconsider participating in the study. For this purpose,values were slightly high, suggestive of the effects of the highwe will repetitively send out letters encouraging participation in

proportion of obese individuals. It is considered necessary that

this study and make approaches to specific target groups. At thedyslipidemia-related test items and diseases be evaluated withsame time, we will take all measures imaginable forcaution.

determination,

besidesthecollectionofencouraging participation in this study, including PR activities

The UNSCEAR pointed out in its report the possibility ofusing websites, posters, and other information dissemination

future increases in the occurrences of hypothyroidism. Of themethods that automatically attract the attention of the target

male checkup examinees during the period from January 2016

audience regardless of their awareness.

to October 2018, 368 persons (7.0%) showed thyroid functional

Recently, individuals kept waiting are increasing despite theirdisorders. Those with high TSH levels were, however, 78

expressed intention to participate in this study; this must be

persons (1.6%). We consider it necessary to keep a close eye on

dealt with urgently. Various possible causes are beginning to be

future trends in the prevalence and incidence of hypothyroidism.

- 19 （ 19 ）−111−

The results of cancer checkups, including fecal occult blood
tests, showed no anomalies. The total cancer incidence and

F. Research publications

prevalence among the health checkup examinees were 195

1. Papers published in academic journals

persons and 3.8%, respectively. Eight individuals suffering two

Toshiteru Okubo: Epidemiological Survey: From thetypes of cancer were observed along with another suffering

Experiences of Hiroshima and Nagasaki to Fukushima: Journal

three types of cancer. The breakdown of the total incidence wasof Clinical and Experimental Medicine, 239(10):995-1000,

approximately as follows: 35 individuals with gastric cancer; 39

2011.

with colon cancer; 18 with lung cancer; 15 with thyroid cancer;
and 30 with prostatic cancer.

Toshiteru Okubo: Epidemiological Study Targeting Nuclear
Emergency Workers at the TEPCO Fukushima Daiichi Nuclear

The current age-adjusted proportion of smokers among themale checkup examinees was 32.9%, slightly higher than thePower Plant: Occupational Health Management, 27(3): 39-46,
2016.

results of the National Health and Nutrition Survey. The

Toshiteru Okubo: "Epidemiological Study Targeting Nuclear

proportion of individuals with a habit of drinking alcohol once

Emergency Workers at the TEPCO Fukushima Daiichi Nuclear

a month or more among the health checkup examinees wasPower Plant" - Progress Report: Health Development, 20(3):83-

84.2%, which is considerably higher than the total proportion of93, 2016.

42.1% among male adults (with the following drinking

Toshiteru Okubo: "Epidemiological Study Targeting Nuclear

frequencies all combined: every day; 5 to 6 days/week; 3 to 4

Emergency Workers at the TEPCO Fukushima Daiichi Nuclear

days/week; 1 to 2 days/week; 1 to 3 days/month as per

Power Plant": UPDATE, 27 (1): 29-30, 2016.

Comprehensive Survey of Living Conditions 2016). It was

Toshiteru Okubo: RERF Epidemiological Study of Healthconsidered necessary to observe with close attention the

Effects in Fukushima Emergency Workers: UPDATE, 27(1):occurrences of diseases known to be affected by alcohol

29-30, 2016.

consumption, including lifestyle-related illnesses.

Hiroko Kitamura, Toshiteru Okubo, Kazunori Kodama,
Nuclear Emergency Workers Study Group: Epidemiological

E. Conclusions

study of health effects in Fukushima nuclear emergency

The approaches made to the survey target population resulted

workers–study design and progress report: Radiation protectionin the acquisition of consent to participation in this study fromdosimetry, ncy136, https://doi.org/10.1093/rpd/ncy136, 2018.

7,270 persons, or 36.7% of the target population, as of October
31, 2018. To increase the future study target population, it is

2. Conference presentations

necessary to reduce the 6,976 non-respondents and to urge the

Kazunori Kodama: Epidemiological Study Targeting Nuclear

3,334 participation refusers to reconsider participating in thisEmergency Workers at the TEPCO Fukushima Daiichi Nuclear

study. From the next fiscal year onwards, we would like toPower Plant: Application of the Know-how Developed throughencourage participation in this study, using new tools, andthe Survey of Radiation Health Effects of Atomic Bombcontinue our efforts to further expand the cohort size while

Explosions: Second Conference on Epidemiological Study

moving this epidemiological study forward.

Targeting Nuclear Emergency Workers at the TEPCO

Fortunately, a majority of the checkup examinees expressed
their intention to participate in the research: 98.5% or more of

Fukushima Daiichi Nuclear Power Plant, 11 March, 2016,
Kitakyushu.

the health checkup examinees consented to cooperate for all

Waka Oishi: Epidemiological Study Targeting Nuclear

items of the study. For storage of biological test samples, 99%

Emergency Workers at the TEPCO Fukushima Daiichi Nuclear

or more consented to the storage of their blood and urine

Power Plant: An Outline of the Clinical (Health Checkup) Study

samples; and 98.5% consented to the storage of their bloodbased on the Experience from the RERF Adult Health Study:

samples for use in future human genome and genetic analysis

The Second Conference on Epidemiological Study Targeting

research. Moreover, in the statistical results obtained this time,

Nuclear Emergency Workers at the TEPCO Fukushima Daiichi

there were no items indicating particularly significant health

Nuclear Power Plant, 11March, 2016, Kitakyushu.

anomalies in the group. Therefore, it was concluded that thisHiroko Kitamura, Kazunori Kodama, Toshiteru Okubo:group had no bias in the baseline health conditions and hence

Epidemiological study of health effects in Fukushima nuclear

constituted a desirable group as a study target population. It is,emergency workers–study design and progress report: The

however, necessary, from now onwards, to watch with strong

UNSCEAR Meeting in Tokyo, Fukushima Follow-up Projectinterest(FFUP), 15 November, 2016, Tokyo.

somerecognized

tendencies, including higher

Toshiteru Okubo: Epidemiological Study Targeting Nuclear

proportions of individuals with obesity, hyperlipidemia, acurrent smoking habit, and a drinking habit.

Emergency Workers at the TEPCO Fukushima Daiichi Nuclear- 20 （ 20 ）−112−

Power Plant: The 63rd Conference of the Japanese Society ofOccupational Medicine and Traumatology, 17 November, 2017,
Kitakyushu.
Hiroko Kitamura, Toshiteru Okubo, and Kazunori Kodama:
Epidemiological study of health effects in Fukushima nuclear
emergency workers (Nuclear Emergency Workers Study;NEWS)-study design and progress: The 15th Coordination
Meeting of the WHO Radiation Emergency Medical
Preparedness and Assistance Network (REMPAN). 4 July, 2017,
Geneva, Switzerland.
Toshiteru Okubo: Epidemiological Survey of Emergency
Workers Engaged in Accident Response Work at TEPCO
Fukushima Daiichi Nuclear Power Plant: Industrial Medicine
Workshop, Okayama Prefectural Medical Association, 2018,
Okayama.
Hiroko Kitamura: Epidemiological Study Targeting Nuclear
Emergency Workers at the TEPCO Fukushima Daiichi Nuclear
Power Plant: Change in Study Participants: Fourth Conference
on Epidemiological Study Targeting Nuclear Emergency
Workers at the TEPCO Fukushima Daiichi Nuclear Power Plant,
14 March, 2018, Kitakyushu.
G. Intellectual property rights acquiredNone- 21 （ 21 ）−113−

II. Working-Group Research Reports(by Individual Subcommittees)−115−Industrial Disease Clinical Research Grants
Working-Group Research Report

Epidemiological Study Targeting Nuclear Emergency Workers at the TEPCO
Fukushima Daiichi Nuclear Power Plant
Approaches to the Study Target Population: Characteristic analysis of the Study
Target Population

Principal Investigator: Toshiteru Okubo, Radiation Effects Research Foundation (RERF),
Consulting Researcher
Co-Investigator: Hiroko Kitamura, Sub-Chief Researcher, Hiroshima Clinical Research
Department, Radiation Effects Research Foundation (RERF)

Abstract
This report looks back on the approaches made to the study target population during the first cycle of this study(the five years from its start) and summarizes the characteristics of the study participants. Calls to engage individual
study target persons in this study were made primarily by mail. At the same time, various PR activities were also
promoted without narrowing it down to any specific audience. The results of the approaches made are as follows,
as of October 31, 2018: Of the study target population of 19,808 individuals, 7,270 (36.7%) showed interest in
participation (6,656 agreed to take a health checkup; 614 agreed to cooperate otherwise in the study); 3,334 (16.8%)
declined participation; 6,976 (35.2%) returned no response; 1,828 (9.2%) were addressees unknown at the addressused; 254 (1.3%) were deceased; and 146 (0.7%) were unaccountable for due to other reasons.
* Those "unaccountable for due to other reasons" were individuals currently not regarded as study participants due
to reasons including their intention still being checked or their consent to study participation being inconsistent.
In order to increase the number of study participants in the future, it is necessary to reduce that of non-respondents
and to encourage participation refusers to reconsider participating in the study. For this purpose, consideration isunderway to send by mail calls for participation in this study, and to make approaches to specific target groups. At
the same time, all measures imaginable to encourage participation in this study will be taken, including PR activities
using a website, posters, and other information dissemination methods that automatically attract the attention of thetarget audience regardless of their awareness.
In addition, recently, those kept waiting for a health checkup are increasing despite their expressed intention toparticipate in this study. This problem should also be dealt with urgently. Various possible causes are beginning tobe identified, including: insufficient response capacity of the health checkup institutions (hereinafter referred to as"health checkup institutions"); or geographical difficulties for the emergency workers living too far from research
partner institutions to take a health checkup. First and foremost, partnerships with additional health checkup
institutions must be established in areas with a fast-growing waiting list. A change should be made from the current
strategies for soliciting cooperation.
A. Study objective

radiation exposure levels experienced were, however, equal toThis study is a prospective cohort study that performs

or below the radiation exposure threshold said to cause known

lifelong follow-up of the emergency workers (hereinafter

health effects. With a target population of the size herein,referred to as "study target population (or individuals)") spreadtherefore, the diseases with radiation effects confirmed byacross the country. The first cycle of this study (the five years

previous surveys on atomic bomb survivors and others wouldfrom its start) aimed to obtain as many study participants as

only occur intermittently. Therefore, the success of this study

possible from the study target population of 19,808 individuals

depends on the maximization of the population to be observedin order to lay down the foundation for the framework for thein a long-term epidemiological survey, because this study

lifelong follow-up survey.

explores an exposure region with no known risks to verify the

The objective of this study is to investigate the radiation

existence of effects to which the so-called "No-Threshold

exposure effects in the human body among this study target

Hypothesis" (population. Hence, a long-term prospective follow-up survey isobservation than in conventional epidemiological surveys is therequired. For most of the study target population herein, theprerequisite. Based on such an awareness of the issue, this

22 ）
（- 23
−117−

,

) applies. In other words, a longer-term

report presents a wide range of efforts made to increase theon the progress made in the study to the general public besides

number of study participants during the first cycle of this study

the study target population. Moreover, a newsletter has been(the five years from its start), examines the effectiveness of eachpublished once a year. These media were also used to makeeffort, and considers measures to take in the future.

approaches to non-participants. The website includes a screen

The promotion of this study is expected to help determine thedesigned to accept individual access from study target

relevance of diseases to radiation exposure and the emergency

individuals, so that study target individuals with their personal

work through a comparison of the future frequency ofidentification number registered and their password set canoccurrence of diseases among the emergency workers with that

submit a completed consent form, notify the change in theirof the same diseases among those other than the emergency

whereabouts or phone number, and apply for a health checkup.

workers.

These approaches made during the five-year first phase of thisstudy have been summarized into a list (Table 1).

B. Study methodology
Types of approaches

Approaches tailored to the characteristics of target

During their engagement in the emergency work, the study

individuals

target individuals belonged either to Tokyo Electric Power Co.,

While the study target individuals in this study differ

Ltd. (then and now Tokyo Electric Power Company Holdings,

diversely in work-related characteristics, such as occupation orIncorporated, hereinafter abbreviated as "TEPCO") or to one ofwork history, the difference most worthy of note for this study

the companies outsourced with the emergency work fromis the difference in radiation work experience. The target

TEPCO. Hence, these companies would supposedly provide theindividuals with prior engagement in radiation work have amost effective channels for encouraging participation in thishistory of radiation exposure and hence are expected to differ instudy. However, most of the study target individuals, andcumulative exposure dose from those temporarily engaged in

especially

underradiation work for the emergency work. The study target

construction-related companies, had already changed their

population includes a large number of workers who wereorganizational affiliation from that at the time of the emergency

temporarily employed to deal with the emergency caused by thework, because this study started more than three years after the

nuclear reactor explosion accident. Many of these workers are

end of the emergency work period. Besides, it was one of theassumed to have been employed on temporary contract terms.

fundamental policies in this study to provide study-related

Consequently, the study target population consists of

explanations strictly on an individual-by-individual basis andindividuals with various combinations of differences in priorlimit the study target individuals to those with expressedradiation work experience, labor contracts, and other conditions,consent to participation, rather than call out for participation inamong other characteristics.

those

engagedincontingent

work

this study through their affiliated companies. Therefore, though

When it comes to investigating the effects of radiation

there was some cooperation received from the companies in

exposure due to the emergency work, the availability of pastcalling out for participation in this study, all applications for

exposure histories based on the Radiation Work Passports

participation in this study were accepted in principle on anissued by the Radiation Dose Registration Center of theindividual-by-individual basis.

Radiation Effects Association (REA) would allow a more

The most basic method of making approaches is sending by

accurate study than one based exclusively on the exposure doses

mail calls for participation in this study. Phones and otherduring the emergency work. The emergency workers hereinmodes of personal communication were used to answer

have all been registered at the Center and issued a Radiationinquiries about the formalities for participation, or to provide

Work Passport. Hence, their exposure doses during theadditional explanations. As the methods of calling out for

emergency work are all available in theory. The knowledge ofintentional non-responders or those who had been unreachable

the exposure levels they experienced earlier than that wouldby mail due to the change in whereabouts, PR methods intended

allow for a more accurate analysis of their exposure doses andfor a broad unspecified audience were employed. Specifichealth conditions.

examples included preparation of posters and enclosure of

In addition to the above-mentioned combination of labor

flyers in multi-purpose mail correspondences. The latter

contracts and other conditions, companies differed in their

included requests for their enclosure in the envelope of thewillingness to cooperate in this study. Hence, a decision wasquestionnaire for the Current Status Survey conducted under themade to encourage participation in this study individually on a

MHLW once a year as part of the long-term health managementcompany-by-company basis. A typical example is provided byprovided to the emergency workers.

TEPCO. Considering that the accident-struck power plant

A website for this study was created to provide information

belongs to TEPCO in the first place, it may be a matter of course（- 24 ）
−118−

that among all the companies concerned, TEPCO has the mostsignificant number of participants, though the number includes
those collectively deemed as its affiliated individuals, namely,
professional engineers urgently mobilized to deal with theaccident and other external experts involved voluntarily as
individuals, such as academic experts and industrial doctors.
TEPCO has a positive stance regarding cooperation in the study.
For example, TEPCO decided to deem the time spent by its
employees for the health checkup for this study as part of thetime worked by them, thereby providing a condition mostconducive to target individuals' participation. Additionally, thecompany decided to regard the health study conducted in thisstudy as an alternative to the regular health checkup compulsory
for workers under the Occupational Safety and Health Act. Thismeans the exemption of the regular health checkup of thepertinent year, which resulted, among the target individuals, ina higher motivation to take health checkups, namely, a higher
willingness to participate in the study.
Although their cooperation may not have been comparable incontent to that of TEPCO, many of the other companies
encouraged their employees to participate in this study. Thisencouragement, however, applies only to those who were theiremployees at the time they encouraged participation. In the caseofcompanies

such

as

construction

companies,

suchencouragement was impossible because the majority of their
on-site workers had been contingency workers and had alreadyleft their positions when the letter of request for participation inthis study was sent.
Because of the above circumstances, the results ofapproaches made to engage target individuals in the study arereported here separately for those with affiliation with TEPCO
and those without.

（- 25 ）
−119−

2

1
1

0

2

1

2

3

4

5

6

7

8

9
1

0

2

1

2

3

5

● TEPCO
●

4

6

7

8

9
1

0

2

1

2

3

5

●

4

● TEPCO●● Checkup refusers● Website opened● Non-respondents● Non-TEPCO●●● TEPCO●●● TEPCO

●

●

●
●

●

（ 26 ）−120−●●(ix) Individual approaches to NIRS healthcheckup examinees

9● TEPCO(vii) Enclosure of epidemiological study-related
information in envelopes of mail from NFIHO(viii) Phone calls

8

1
6

7

●

(iv) Corporate explanatory meetings (principal
contractors and subcontractors)(v) Approaches from related personnel ofprincipal contractors(vi) TEPCO's EPICON Booth

7

1

1

FY 2017● High dose

98

FY 2018
1
1

1
0

12

26

In FY 2015, the tasks of making phone-calls for confirming the receipt of the letter concerning the intention to participate and soliciting the submission of the "letter of consent to participation" were outsourced. In FY 2018, phone contact was made with non-respondents identified from among those registered in the database as target individuals exposed to a dose of 100 mSv or more during the
emergency work. Consideration is underway to contact by phone in stages those exposed to doses below 100 mSv. Following the increase in the number of health checkup institutions, phone calls were made to encourage the switching of preferred health checkup institutions.
Those registered in the database as workers exposed to a dose of 250 mSv or more during the emergency work undergo health checkup once a half year at the NIRS as exceptions. These occasions were used as opportunities to meet target individuals directly and encourage them to participate in this study.

In FY 2017, the TEPCO's Headquarters, the Fukushima Daiichi NPP, and the Kashiwazaki-Kariwa NPP each set up an EPICON Booth in sync with TEPCO's spring in-house health checkup. In FY 2018, the Headquarters, the Fukushima Daiichi and Daini NPPs, and the Kashiwazaki-Kariwa NPP did the same. For FY 2019, it is planned to identify the departmental affiliations of non-respondents
and pay visits to establishments other than those installed with an EPICON Booth.
Since FY 2016, the NFIHO has, as requested, been enclosing information on this epidemiological study in the envelopes of the current status questionnaires or booklets they issue.

Contacts were made with the persons in charge of radiation control or safety and health at 14 principal contractors. The persons in charge at virtually ten contractors encouraged their in-house non-responding target individuals to reply.

In FY 2014, a letter of request for participation in the preliminary survey was sent to target individuals living in Fukushima Prefecture. In FY 2015, a letter of request for participation in the survey was sent to non-TEPCO-affiliated target individuals all over the country.
In FY 2014, target individuals living in Fukushima Prefecture were requested to participate in the preliminary survey, and a written encouragement to take health checkup was sent out by mail. Written encouragements to take health checkups have been sent by mail to non-TEPCO-affiliated target individuals all over the country since FY 2015 and TEPCO-affiliated target individuals since FY
2016. Dispatches by mail are made all the time, including those made upon individual request. At the same time, broadcast mailing is also conducted per a plan factoring in different types of addressees such as "non-respondents," "addressees unknown," and "non-participants in the preliminary survey."
In September 2017, accepting written consent via the website was started. In FY 2017, correspondence was sent by mail to reluctant target individuals, such as "non-respondents" and "checkup refusers," in an attempt to obtain their consent to cooperate in the study. TEPCO's EPICON Booths in FY 2017 and 2018 were intended for non-respondents, who were then-current employees relatively
shy of the health checkup, and hence the main focus was placed on obtaining their consent for cooperation in the study.
In July FY 2015, an explanatory meeting was held for TEPCO and 15 principal contractors. In August, explanatory meetings for subcontractors were held in Tokyo, J Village, and Kashiwazaki, with the attendance of 533 individuals.

6● Non-TEPCO●(i) Requests for participation (by mail)(ii) Encouragement to take health checkups (bymail or otherwise)(iii) Acquisition of consent (mail/website)

51● Participation pending(ix) Individual
approaches to NIRS
health checkup
examinees

4

1

1

FY 2016● Re-dispatch to(viii) Phone calls

3

1● Individual support(iv) Corporate
explanatory
meetings (principal
contractors andsubcontractors)(v) Approaches from
related personnel ofprincipal contractors(vi) TEPCO's
EPICON Booth(vii) Enclosure of
epidemiologicalstudy-related
information inenvelopes of mailfrom NFIHO

2

1

1

FY 2015● Approaches by age(iii) Acquisition ofconsent (by mail, via
website, orotherwise)● Preliminary(ii) Encouragement
to take healthcheckups (by mail orotherwise)

1

0

1

FY 2014● Preliminary(i) Requests forparticipation (by
mail)

1

1

Table 1

● Individual support

Individual approaches

TEPCO's internal discussions on their cooperation in this study,1) Approaches made to target individuals unaffiliated withand lagged behind the first contact with non-TEPCO-affiliated

TEPCO

target individuals by more than one year. The first contact with

The initial contact with target individuals unaffiliated with
TEPCO

was

made

throughthe"Noticeofthe former was made through the "Questionnaire on Readiness

Study

to Participate in Health Checkups" sent by mail to their personal

Commencement" sent by mail to their personal addresses inaddresses in August 2016. In November, with cooperation fromJanuary 2015. Then, after an explanatory meeting held to ask

the company, the "Questionnaire on Readiness to Participate in

the managing supervisors of the major principal contractors for

Health Checkups" was redistributed by in-house mail to thecooperation in this study, the "Questionnaire on the Intention to

non-respondents to the same Questionnaire sent by mail in

Participate in Health Checkups" was sent by mail to theAugust.

personal addresses of non-TEPCO-affiliated target individuals

In April to May 2017, with cooperation from the company,

from July to August 2015. To positive respondents to theconsultation booths for urging participation in this study were

Questionnaire on the Intention to Participate in Healthset up at the regular health checkup venues on the premises of

Checkups, the "Application Form for Participation" was sent by

their Headquarters, the Fukushima Daiichi Nuclear Power Plant,

mail in order of receipt of their responses. In August 2016, theand the Kashiwazaki-Kariwa Nuclear Power Plant, each with a"Application Form for Participation" was sent by mail to non-relatively large number of non-respondents, in order to provide

respondents. In September, to the non-respondents to theface-to-face consultation regarding participation in this study,"Questionnaire on the Intention to Participate in Healthincluding encouragement for submission of the "Form of

Checkups," the "Questionnaire on Readiness to Participate inConsent to Cooperation in the Study" and the "Questionnaire on

Health Checkups" was sent by mail in order to urge them to takeReadiness to Participate in Health Checkups."a health checkup.

In September of the same year, with cooperation from the2) Approaches made to major related companies

company, the "Form of Consent to Cooperation in the Study"

In June 2017, 14 major principal contractors belonging to theand the "Questionnaire on Readiness to Participate in Health

Fukushima Daiichi Nuclear Power Plant Safety and Health

Checkups" were distributed by their in-house mail to non-

Promotion Council (group of collaborative companies) were

respondents other than those affiliated with the Headquarters,

requested, through the liaison person of TEPCO's Radiological

the Fukushima Daiichi Nuclear Power Plant, and the

Health and Safety Center, to appoint a liaison person in charge

Kashiwazaki-Kariwa Nuclear Power Plant. In January 2018, aof communications related to this study with the Researchdecision made was to make calls for a change of mind about

Secretariat. Following the receipt of replies from 10 companies

cooperation in this study and participation in health checkups toinforming the names of their liaison persons, a request for

the known negative respondents to the "Questionnaire oncooperation in this study was made to each company throughReadiness to Participate in Health Checkups." Then, the "Formtheir liaison person. Although they differed in the content ofof Consent to Cooperation in the Study" and the "Questionnaire

actual cooperation, eight companies encouraged their affiliatedon Readiness to Participate in Health Checkups" were mailed.

non-respondents to reply. Calls for a change of mind about

Results of PR activities

participation in health checkups were first made in December

In September 2016, the first issue of "NEWS Health Checkup

2017 to the negative respondents to the "Questionnaire on theNews" was published for such purposes as the provision ofIntention to Participate in Health Checkups," and then in

information to all the emergency workers falling within theJanuary 2018 to the negative respondents to the "Questionnaire

scope of this study. In September 2017, the second issue wason Readiness to Participate in Health Checkups." At the same

published. A decision was made to publish subsequent issues

time, the "Form of Consent to Cooperation in the Study" andperiodically once a year. The coverage of NEWS Healththe "Questionnaire on Readiness to Participate in Health

Checkup News included the number of study participants, theCheckups" were sent by mail in order to uncover hidden study

trends in the number of health checkup examinees, explanations

target individuals who had an intention to cooperate in the study

on the health checkup items in this study, information on thethough were not ready to take a health checkup at the moment.

partner health checkup institutions across the country, and(All the materials sent by mail to make the above approaches

health-related topics.
In the descending order of the number of their health checkup

are found in the FY 2017 Study Report.)
3) Approaches made to target individuals affiliated withexaminees, research partner institutions are asked to provide

TEPCO

photographs full of local color for use on the cover page of

The encouragement of TEPCO-affiliated target individuals toNEWS Health Checkup News.

participate in the study remained on hold until the end of（ 27 ）−121−

In September 2017, a website for this study was opened forthe publicity of this study per se, and also as the access gate fortarget individuals to submit their application for participation inthis study. Figure 1 shows the trend in the number of views of
the website per day for the website since its opening (Figure 1).
The number of viewers per day temporarily shot up
immediately after the opening, but soon started to drop
gradually down to 10 or fewer persons per day three months
after. In March 2018, however, a listing advertisement* wasintroduced as one of the methods of guiding target individuals
to the website for this study. Then, following the start of abanner advertisement campaign in March 2018, the number ofviewers of the website increased to the order of several hundred
per day. After the end of the banner advertisement campaign,
the number remained at approximately 10 to 30 persons per day.
Hence, it seemed evident that the website owed the increase in
the number of its viewers to the effect of the banneradvertisements. After that, the number of visits has remained at
an average level. Accordingly, the cumulative number ofvisitors has been slightly but steadily increasing as time elapses(Figure 2).
* Listing advertisement is an advertising technique that displays
advertisements associated with keywords searched by internet
search engine users on the search results page. Though intended
for commercial purposes, this technique was adopted this timein expectation that listed adverts would guide study target
individuals among an indefinitely large number of internet users
to the website for this study, and help prompt them to apply forparticipation in this study from the website.

（ 28 ）−122−

Website's viewers
website's viewers

Cumulative number of

Figure 1. Trend in the number of viewers per day after the opening of the website

Figure 2. Trend in the cumulative number of viewers for the website

1 ）
（ 29
−123−

Table 2: Proportions of participants and others in this study by age
Participation refusers

Addressees unknown

Age group
total

Study participants (%)

20-29-yrs old592

130 (21.9%)

112 (18.9%)250 (42.2%)

97 (16.3%)

1 (0.1%)2 (0.3%)30-39-yrs old2752

807 (29.3%)

379 (13.8%)1094 (39.8%)

437 (15.8%)

11 (0.3%)

24 (0.9%)

40-49-yrs old

5221

1923 (36.8%)

820 (15.7%)

1963 (37.7%)

461 (8.8%)

26 (0.4%)

28 (0.5%)

50-59-yrs old

5759

2320 (40.2%)

978 (17.0%)

1908 (33.3%)

449 (7.7%)

60 (1.0%)44 (0.8%)

60-69-yrs old

4781

1857 (38.8%)905 (18.9%)1520 (31.9%)340 (7.1%)

124 (2.5%)

35 (0.7%)696

233 (33.5%)

140 (20.1%)

241 (34.9%)

44 (6.3%)

32 (4.5%)

6 (0.9%)

7270

3334

6976

1828

254

70-yrs old orover
Unknown
Total(%)

Non-respondents (%)(%)

Deceased (%)

Others (%)

7
19808

7

20-29-yrs old

30-39-yrs
old40-49-yrs old 50-59-yrs old 60-69-yrs old 70-yrs old or overFigure 3. Comparison of the proportions of study participants (by age)

20-29-yrs old

30-39-yrs old

40-49-yrs old 50-59-yrs old 60-69-yrs old

70-yrs old or overFigure 4. Comparison of the proportions of participation refusers (by age)

20-29-yrs old

30-39-yrs old

40-49-yrs
old50-59-yrs old

60-69-yrs
old

70-yrs old or overFigure 5. Comparison of the proportions of non-respondents (by age)

2 ）
（ 30
−124−

146

Study participants (non-TEPCO employees)

Participation refusers (TEPCO
employees)

Participation refusers (non-TEPCO employees)

Oct. 2018

Sept. 2018

Jul. 2018

Aug. 2018

Jun. 2018

Apr. 2018

May 2018

Mar. 2018

Jan. 2018

Feb. 2018

Dec. 2017

Oct. 2017

Nov. 2017

Sept. 2017

Jul. 2017

Aug. 2017

Jun. 2017

Apr. 2017

May 2017

Mar. 2017

Jan. 2017

Feb. 2017

Dec. 2016

Oct. 2016

Nov. 2016

Sept. 2016

Jul. 2016

Aug. 2016

Jun. 2016

Apr. 2016

May 2016

Mar. 2016

Jan. 2016

Feb. 2016

Dec. 2015

Aug. 2015
Sept. 2015
Oct. 2015
Nov. 2015

Number of individuals (persons)

Study participants (TEPCO
employees)

Non-TEPCO employees(1): The Questionnaire on the Intention to Participate in Health Checkups was sent by mail.
(2): The Form of Application for Participation was sent by mail to the positive respondents to the Questionnaire on the Intention to Participate in Health Checkups.
(3): The Questionnaire on Readiness to Participate in Health Checkups was resent to non-respondents to (2).
(4): The first issue of NEWS Health Checkup News was sent by mail.
(5): The Questionnaire on Readiness to Participate in Health Checkups was resent to non-respondents to (1).
(6): The major principal contractors encouraged the workers under their charge to return a reply.
(7): The second issue of NEWS Health Checkup News was sent by mail.
(8): The NEWS website was opened.
(9): Written encouragement for a change of mind about cooperation in this study was sent by mail along with a consent form and the Questionnaire on Readiness to Participate in
Health Checkups to those who had refused to participate in more than one health checkup.
(10): As regards addressees unknown, the Questionnaires on the Intention/Readiness were sent to those whose whereabouts had been located.
TEPCO employees
a: The Questionnaire on Readiness to Participate in Health Checkups was sent by mail.
b: The first issue of NEWS Health Checkup News was sent by mail.
c: The Questionnaire on Readiness to Participate in Health Checkups was sent by in-house mail to non-respondents to (a).
d: Consultation booths were set up on the premises of the Headquarters, the Fukushima Daiichi NPP, and the Kashiwazaki-Kariwa NPP.
e: The second issue of NEWS Health Checkup News was sent by mail.
f: The NEWS Website was opened.
g: The Form of Consent to Cooperation in the Study and the Questionnaire on Readiness to Participate in Health Checkups were sent by in-house mail to the non-respondents to (a)at establishments other than the Headquarters, the Fukushima Daiichi NPP, and the Kashiwazaki-Kariwa NPP.
h: Written encouragement for a change of mind about cooperation in this study was sent by mail along with a consent form and the Questionnaire on Readiness to Participate in
Health Checkups to those who had refused to participate in more than one health checkup.
i: Written correspondences were sent by TEPCO's in-house mail, and consultation booths were set up on the venues of TEPCO's regular health checkup.
j: As regards addressees unknown, the Questionnaires on the Intention/Readiness were sent to those whose whereabouts had been located.

Figure 6: Trends in the numbers of study participants and participation refusers per month
C. Study results

The total numbers since April 2017 are based on the expanded

1) Trends in study participants, participation refusers,

definition of study participants. Additionally, though currently

non-respondents, addressees unknown, and others

still small in number but expected to increase in the future,

At the beginning of this study, calls for participation in thisdeceased individuals were classified into a new category

study were made on the assumption that "participating in thisseparate from the above four categories. A decision made wasstudy = taking health checkups." Many among the study target

to classify the following individuals into the "Others" category:

population are, however, active workers, who were heard to99 persons ineligible as target individuals of an epidemiologicalopine, e.g., that they cannot afford the time to take healthstudy, such as those living abroad or those whose whereabouts

examinations conducted for this study, or that they do not feel

was unknown from the beginning; those who replied unclearly

the need because they take in-house health checkups. Hence,about their intention as to participation or failed to respond tothe members of the Operational Committee of this study agreed

inquiries about inconsistencies between some items in theto include in the number of study participants, the study target

written consent received prior from them; and those otherwise

individuals with an expressed intention to "cooperate in theineligible.

study though not ready to take a health checkup at the moment."

3 ）
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The response status as the results achieved through theapproaches made to target individuals during the period from

Figure 6 shows the number of replies per month since thethe initial approach by mail in 2015, the first year of the firststart of calls for participation in this study, along with otherphase, to the end of October 2018, the fifth year is shown instatistical data, for those with affiliation with TEPCO and those

Table 2 by ten year-bracketed age as of the initial year for eachwithout. The figure shows the points of time at which majorof the six categories. Of the statistical target population of

approaches were made. The number of study participants

19,808 individuals in (Table 2), 7,270 persons (36.7%) showed

increased over time as a result of the approaches made tointerest in participation, 3,334 (16.8%) declined participation,encourage participation in this study, including encouragement

6,976 (35.2%) returned no response, 1,828 (9.2%) wereto reply by mail, by in-house mail, or via the major principal

addressees unknown at the address used, 254 (1.3%) were

contractors. As explained above, calls for participation were

deceased, and 146 (0.7%) were unaccountable for due to othermade separately for TEPCO employees and those of otherreasons. A look at the proportion of study participants by age

companies, so the figure shows the separate trends for thegroup reveals that the proportion of participants increased withformer and the latter (Figure 6).

age among those in their twenties to forties, and showed a slight

Table 3 shows the proportions of study participants fordrop after the peak marked in the 50- to 59-years-old age

TEPCObracket.

proportion of participants in this study strikingly differs

employees

andnon-TEPCO

employees.

The

The proportion of non-respondents was highest among

between the two categories. Only 29.3% of non-TEPCO

younger individuals while approximately flat among those inemployees expressed their intention to participate, whereas

their fifties and older. The proportion of participation refusers

58.5% of TEPCO employees did so. Moreover, the proportion

was high among both the younger and older age groups while aof non-respondents was lower among TEPCO employees

little low among the intermediate-age group (Figures 3 to 5).

(Table 3).

2 ）
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Table 3: Proportions of participants and others in this study among TEPCO employees andnon-TEPCO employees
Total by

Study participantsParticipation

Non-respondents

Addressees

affiliation(%)

refusers (%)(%)

unknown (%)

16662

5182(31.1%)2774(16.6%)6540(39.3%)

3146

2088(66.3%)

560(17.8%)

19808

7270

3334

Non-TEPCO
employees
TEPCO
employees
Total

Deceased (%)

Others (%)

1785(10.7%)253(1.5%)128(0.8%)436(13.9%)43(1.3%)1(0.0%)

18(0.6%)

6976

1828

254

146

Table 4: Proportions of participants and others in this study by dose
Total by

Study participantsParticipation

Non-respondents

Addressees

dose

(%)

refusers (%)(%)

unknown (%)

Deceased (%)

Others (%)

Below 5 mSv

9336

3284 (35.2%)

1721 (18.4%)3326 (35.6%)776 (8.3%)

119 (1.3%)

5 mSv or more to below 10 mSv

2854

1003 (35.1%)

426 (14.9%)

1071 (38.1%)

314 (11.0%)

31 (1.1%)

110 (1.2%)
9 (0.3%)

10 mSv or more to below 20 mSv

3265

1095 (33.5%)507 (15.5%)1243 (38.1%)

367 (11.2%)

47 (1.4%)

6 (0.2%)20 mSv or more to below 50 mSv

2816

1119 (39.7%)

427 (15.2%)

950 (33.7%)

275 (9.8%)40 (1.4%)

5 (0.2%)

50 mSv or more to below 100 mSv

881

505 (57.3%)

147 (16.7%)

184 (20.9%)

32 (3.6%)

7 (0.8%)6 (0.7%)

100 mSv or more to below 150 mSv

139

111 (79.9%)21 (15.1%)

6 (4.3%)0 (0.0%)0 (0.0%)1 (0.7%)150 mSv or more37

29 (78.4%)

6 (16.2%)2 (5.4%)0 (0.0%)0 (0.0%)0 (0.0%)Non-respondents, persons with unknown addresses, and others
Participation refusers (non-TEPCO employees)
Participation refusers (TEPCO employees)
Study participants (non-TEPCO employees)

Oct. 2018

Sept. 2018

Jul. 2018

Aug. 2018

Jun. 2018

Apr. 2018

May 2018

Mar. 2018

Jan. 2018

Feb. 2018

Dec. 2017

Oct. 2017

Nov. 2017

Sept. 2017

Jul. 2017

Aug. 2017

Jun. 2017

Apr. 2017

May 2017

Mar. 2017

Jan. 2017

Feb. 2017

Dec. 2016

Oct. 2016

Nov. 2016

Sept. 2016

Jul. 2016

Aug. 2016

Jun. 2016

Apr. 2016

May 2016

Mar. 2016

Jan. 2016

Feb. 2016

Dec. 2015

Oct. 2015

Nov. 2015

Aug. 2015

Sept. 2015

Study participants (TEPCO employees)

Figure 7. Trends in monthly participation in this study (TEPCO employees vs. others)

2 ）
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−127−

Figure 8. Comparison of the proportions of study participants by dose

Figure 9. Comparison of the proportions of participation refusers by dose2) Breakdown of the study participants by exposureand 78.4% for those with 150 mSv or more. This calculationdose levelexcluded 480 individuals with no dose information available

With doses classified into seven categories (below 5 mSv; 5(Table 4).

mSv or more to below 10 mSv; 10 mSv or more to below 20

The proportion of study participants showed differences

mSv; 20 mSv or more to below 50 mSv; 50 mSv or more toamong the dose categories. In the dose categories of 100 mSv

below 100 mSv; 100 mSv or more to below 150 mSv; and 150

or more to below 150 mSv and 150 mSv or more, the proportionmSv or more), this report examines the status of participants inof study participants tended to be notably higher than in thethis study by dose category. The proportions of study

other dose categories (Figure 8). The group exposed to less thanparticipants were as follows: 35.2% for those with exposure

5 mSv tended to show a higher proportion of participationdose of less than 5 mSv; 35.1% for those with 5 mSv or morerefusers than other groups (Figure 9). The proportion of non-to below 10 mSv; 33.5% for those with 10 mSv or more to

respondents also showed differences among the dose categories.

below 20 mSv; 39.7% for those with 20 mSv or more to below

The proportion was lower in 100 mSv or more to below 150

50 mSv; 57.3% for those with 50 mSv or more to below 100

mSv and 150 mSv or more.

mSv; 79.9% for those with 100 mSv or more to below 150 mSv;

3 ）
（ 34
−128−

3) Exposure status by company

through which you have taken a radiological examination or

Table 5 shows the exposure status in two categories, TEPCO

treatment? (hereinafter "receipt of information on medical

and other companies. In the dose categories of 50 mSv or moreradiation exposure doses from examinations and treatments at

to below 100 mSv, 100 mSv or more to below 150 mSv, andmedical institutions"); (4) Do you consent to have your identity

150 mSv or more, TEPCO employees accounted for a larger

checked by certificate of residence in accordance withproportion with the increase in dose.

procedures under the law, in order to allow acquisition of theinformation necessary to confirm and trace your whereabouts

4) Study participation consent status among theafter a future change of residence, check any change in yourstudy participants

name due to reasons such as marriage, and ascertain yourOf the written consent obtained from 5,016 individuals by thesurvival or death? (hereinafter "identity check by certificate ofend of December 2017, those of 4,622 individuals wereresidence in accordance with procedures under the law"); (5)obtained at the time of health checkups. Among the target

Do you consent to receive cancer incidence information fromindividuals with an expressed intention to "cooperate in thethe regional cancer register of the prefecture of your residence,

study though not ready to take a health checkup at the moment,"or the National Cancer Register of the National Cancer Center?

394 persons presented written consent. Regarding their(hereinafter "receipt of cancer incidence information from theintention to cooperate in this study, the following sevenregional cancer register or the National Cancer Register"); (6)questions were asked: (1) Do you consent to receive

Do you consent to receive past and future results of statutory

information on the work situations and exposure dose

medical examinations for occupationally radiation-exposed

measurements during the emergency work and the results ofpersonnel from the health checkup institution? (hereinafter

statutory medical examinations from TEPCO, the principal"receipt of past and future results of statutory medical

contractor, the company, or any other entity affiliated with you

examinations from the health checkup institution"); (7) Do youat the time of the emergency work? (hereinafter "receipt ofconsent to receive the results of thorough screening and otherinformation

dose

related diagnostic information from the medical institution atmeasurements during the emergency work and the results ofwhich you have taken a thyroid checkup (such as blood test,

statutory medical examinations from the then affiliated entity");ultrasound test, or cytological diagnosis)? Your prior consent(2) Do you consent to receive exposure dose-related

shall be obtained specifically regarding the content of reference,

information, including information predating the nuclear power

the medical institution to be referred to, and other relevant

plant accident, stored in the Radiation Dose Registration Center

issues. (If you have never taken any of these tests, please answerof the Radiation Effects Association (REA)? (hereinafter

the question assuming that you will in the future.) (hereinafter"receipt of exposure dose, including dose predating the nuclear"receipt of the provision of the results of thorough screening andpower plant accident"); (3) Do you consent to receive

other related diagnostic information from the medical

information on your medical radiation exposure dose from theinstitution at which you underwent thyroid scanning."). The

medical institution, health insurance society, or any other entity

consent rates fell within the range of 97.0% to 98.3% (Table 6).

on

work

situations

andexposure

2 ）
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−129−

Table 5: Breakdown of TEPCO employees and non-TEPCO employees by dose
Below 5 mSv
Non-TEPCO
employees
TEPCO
employees
Total

8219

5 mSv or

10 mSv or

20 mSv or

50 mSv or

100 mSv or

more to below

more to below

more to below

more to below

more to below

10 mSv

20 mSv

50 mSv

100 mSv

150 mSv

2481

2753

2290

408

46

150 mSv or
more

Unknown

Total

456

16662

9

1117

373

512

526

473

93

28

24

3146

9336

2854

3265

2816

881

139

37

480

19808

Table 6: Consenter ratio for each question in the informed consent questionnaire
Consenters
No. ofpersons
1) Receipt of information on work situations and exposure dose measurements during the emergency work and the

Ratio

Non-consenters
No. ofNon-responders

Ratio

No. of persons

221

3.4%

3
4

persons

6259

96.5%

2) Receipt of exposure dose information, including information predating the nuclear power plant accident

6222

96.0%

257

4.0%

3) Receipt of information on medical radiation exposure doses from examinations and treatments at medical institutions

6248

96.4%

231

3.6%

4

4) Identity check by certificate of residence in accordance with procedures under the law

6164

95.1%

316

4.9%

3

5) Receipt of cancer incidence information from the regional cancer register or the National Cancer Register

6220

95.9%

259

4.0%

4

6) Receipt of past and future results of statutory medical examinations from the health checkup institution

6257

96.5%

221

3.4%

5

6252

96.4%

226

3.5%

5

results of statutory medical examinations from the then affiliated entity

7) Receipt of the results of thorough screening and other related diagnostic information from the medical institution atwhich you underwent thyroid scanning5) Views of those responsible at the companies

After the emergency work was completed, they went back toconcerned

their normal jobs."

When developing a plan for future approaches, it is important"We expect our workers to be very reluctant to cooperate

to hear the opinions of those in direct contact with the

because it has been quite a long time since the emergency work

emergency workers on site, such as those responsible at theended."

companies concerned. So far, opinions including the following"The Radiation Control Department has lost communication

have been heard, providing explanation about the current

with the target individuals. Although they may still be with thesituation, comments on the sluggish increase in the number ofcompany, they are dispersed among other departments or types

study participants, and proposals for improvements:of jobs across the country. If they are no longer radiation"Our workers and we have received documents on studies
titled similarly to yours from other institutions similarly named

workers, the Radiation Control Department has no control overthem."

to yours. Our workers may have failed to reply to some of these

Opinions heard from subcontractors include the following:

documents, assuming they were all the same.""We have no channel to communicate with the radiation"As is common with residential practices in Fukushima,control department of the principal contractor responsible formany of our workers have changed their residential locations

the then emergency workers, and hence have no control over(living alone near the power plant away from their families).

the workers."

Some of the information letters and other correspondence
addressed to them may not have reached them directly.""We are not a radiation work specialist company in the firstplace. Many of the target individuals belong to departments"These workers frequently move between companies. They

completely unrelated to radiation. Since the completion of theare highly likely to leave their current company every time theiremergency work, they have been working back in their originalcontract term nears the end and the work completes."

departments. We have lost our interest in and information about"In the construction industry, it is a common practice tothe nuclear power plant accident or radiation."

employ workers with required skills only for a period need.

"The majority of the target individuals, who do not belong toHence, they move to another site as soon as their contracted

a large company, cannot afford the time to take health checkups

work period is over. On construction sites in general, you often

between tasks."

bump into workers moving between different sites almost on a"Currently, most companies use buses for the collective

daily basis. Unlike manufacturing workers or researchcommute of their workers to and from the Fukushima Daiichi

professionals, few construction workers remain at one place to

Nuclear Power Plant. It is difficult for individual workers towork on one job for a long time."leave for a health checkup in the middle of their work hours.""Back then shortly after the Fukushima Daiichi Nuclear"Assuming that many of the target individuals are working

Power Plant accident, we invited workers with required skills

on TEPCO's sites, we propose that you should conduct healthfrom all over the country to help us with the emergency work.

checkups at the Fukushima Daiichi, Fukushima Daini, and

2 ）
（ 36
−130−

Kashiwazaki-Kariwa Power Plants."

respondents among all the age groups. In both age groups,
however, the proportion of participation refusers was high and

D. Discussions

exceeded 20%. Some of these people may have refused to

As the aim of the first cycle, continuous efforts were pursued

participate in this study because they were still active workers

to collect a sufficient number of study participants to establish

in the latter half of their fifties or sixties at the time of theira cohort. As of October 31, 2018, the number of study

expressed intention to refuse participation, and could not afford

participants was 7,270 persons and accounted for only about

the time to take part and take health checkups. Therefore,

37% of the study target population of 19,808 people.

consideration is underway for activities to encourage

Comparison by age reveals the characteristics of the 20- toparticipation refusers in their sixties and seventies to reconsider

29-year-old age group. This age group showed a hightaking health checkups in this study as one of their healthproportion of both non-respondents and participation refusers,

management methods after retirement.

and hence accounted for a small part of the study participants.

Comparison by dose reveals that TEPCO employees

Even if they were aware of the delivered mail, many of theseaccounted for a progressively higher proportion in the higher

target individuals might have thrown them away without

dose categories. This is probably because the proportion of

returning a reply or even bothering to unseal the envelope.

TEPCO employees was higher among the study participantsMoreover, those in this age group have relatively less healththan that of non-TEPCO employees (Figure 10).

anxiety and hence have a lower motivation to feel like taking

When giving encouragement to reply, the major principal

health checkups. What characterized those in their thirties wascontractors showed differences in their reaction. Morethat they showed the highest proportion of non-respondents

specifically, some companies encouraged only their own

only next to their 20- to 29-year-old counterparts, but have theemployees to do so while others extended their encouragements

lowest proportion of participation refusers among all the age

to the employees of their subcontractors as well. These

groups. The fact may be that, like those in their twenties, many

companies also showed differences in how they encouraged andof these study target individuals did not read or unseal thecollected replies in-house. For example, some companies useddelivered mail. Still, the above characteristics suggest that they

their in-house email or other internal communication methods

might have decided not to participate depending on whether

to encourage replying to sealed letters received from thethey are married or have children. Those in their forties showed

Research Secretariat, others delivered necessary forms via in-a relatively higher proportion of non-respondents. Meanwhile,

house mail, or they internally collected completed forms forthey also showed a relatively low proportion of participation

submission. The actual reply ratio to the number of non-refusers and maintained the proportion of study participants in

respondents widely varied from 7.8% to 57.8% between thethe 30-to-39% range. Those in their fifties had, as theircompanies that directly encouraged individual works to reply.

characteristics, a relatively lower proportion of non-

However, all these companies found it difficult to keep track of

respondents and the highest proportion of study participants

the whereabouts of workers who had already resigned or retired.

among all the age groups. Considering that those in their forties

In order to increase the number of study participants, it isand fifties account for the large part of the study target

necessary to reduce the current approximately 7,000 non-population, a high proportion of study participants in these age

respondents and to encourage participation 3,334 refusers togroups is critically important to secure a cohort. Among thereconsider participating in the study. So far, the primary method

study participants, there were 336 target individuals with anof encouraging participation in this study has been mail. No

expressed intention to "cooperate in the study though not readysealed letter, however, can communicate its content without

to take health checkup at the moment." Of these people, 108

being actively unsealed and read by the recipient. Chances are

were in their forties, and 98 were in their fifties. Although busy

not high that non-respondents and participation refusers will

and in the prime of life, many of those in their forties and fifties

take positive action. In this sense, it is necessary to disseminate

probably participated in this study with the understanding of its

passive information and encouragement for participation in ameaning and purpose. Those in their sixties and seventies

form that can be seen and heard unconsciously. The website

showed a relatively low proportion of non-respondents, and thewould provide an effective method for this purpose.

former in particular included the smallest number of non-

2 ）
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Significantly high vs.
all other dose categories

Figure 10. Comparison of the proportions of non-respondents by dose
E. Conclusions

G. Intellectual property rights acquired

This report described the characteristics of the relationshipbetween the proportion of study participants and theclassification criteria, such as age group, business entity type,and exposure dose level. Not covered herein were many
confounding factors associated with the proportion of study
participants at the time of response. Such factors include themost critical, current employment status besides the number ofdays engaged in the emergency work, the content of the work
engaged in, the presence of subjective symptoms or suffereddiseases during or after the work period, and the family
situations. Therefore, there is no denying the possibility that afactor or factors other than the above-described characteristics
related to the proportion of participants might have had a strong
influence on the results. Hence, it is still too early to saysomething conclusive at this point. The characteristics
presented herein should be regarded strictly as no more thansuperficially observable events without discussing any causal
relationships until those confounding social factors are
sufficiently investigated, so that the proportional contributionof each factor can be analyzed independently from those ofothers.
F. Research publications
1. Papers published in academic journals
None
2. Conference presentations
None

1 ）
（ 38
−132−

None

Industrial Disease Clinical Research Grants
Working-Group Research Report

Statistical Detection Power in the Follow-Up Study on the Number of theemergency workers

Principal Investigator: Toshiteru Okubo, Radiation Effects Research Foundation (RERF), Consulting
Researcher
Research Collaborator: Kyoji Furukawa, Biostatistics Center, School of Medicine, Kurume
University, Professor
Co-Investigator: Hiroko Kitamura, Sub-Chief Researcher, Hiroshima Clinical Research Department,
Radiation Effects Research Foundation (RERF)
Abstract
A solid cancer incidence model was used to estimate statistical detection power. A 40-year-or longer follow-up
study on the entire target population (of approx. 20,000 persons) would allow detection of a 10% increase in solidcancer incidence risk, with a statistical detection power of 80%. Assuming that the proportion of health checkup
participants remains in the current range of 35 to 40%, sufficient detection power cannot be expected without
assuming a risk considerably higher than the above value. Additionally, in cases that presuppose the involvement ofmultiple factors or require the correction of confounding factors, the required number of samples will increase
accordingly. On the other hand, if the disease model aimed to observe not stochastic events but changes in analog
quantities of all samples, a smaller sample size would allow detection.
For this epidemiological survey, it matters most to call out for all members of the given group to participate inthis study, and then to continue observation of target individuals steadily with their consent.
A. Study objective

most cases. The secondary factors are called confounding

In the accident response work at the TEPCO Fukushima

factors, and show behaviors that make it challenging to discern

Daiichi Nuclear Power Plant, the radiation emergency exposure

the causal relationships induced by the primary factors. As adose limit was raised from 100 mSv to 250 mSv for the period

result, corrections become necessary before analyzing thefrom March 14, 2011, to December 16 of the same year. During

effects of the primary factors. This report aims to estimate

this period, 174 individuals among the approximately 20,000

statistical detection power: hence, it limits the disease model

people engaged in the work are estimated to have been exposed

exclusively to the most straightforward factor, i.e., the cancer

to doses exceeding the five-year normal work exposure limit ofincidence, and does not take into consideration the effects of

100 mSv. This study aims to perform lifelong follow-ups of thesecondary factors, i.e., confounding factors.

entire emergency workforce of approximately 20,000 persons

The number of diseases or deaths observed to occur due toto investigate the relationship between their radiation exposure

the involvement of hypothetical factors will be larger than thatand health. In other words, a specific group will undergo long-in the standard group. What an epidemiological survey aims toterm observation to look out for occurrences of healthdo is to determine whether the increase exceeds the range ofanomalies. The health anomalies to observe herein are notcommonly observed random variation. Putting it differently,

restrictively predefined from the beginning. The scope of thiswhen an observed increase exceeds the reference range, thestudy covers occurrences of cancer, which is usually theconclusion will be that "a significant increase occurred." This

principal concerns as radiation effects, and many other diseases,

determination result depends on the size of the observation

including psychological impacts. The occurrence of these target

group. This determination result depends on the size of thediseases involves not only radiation exposure but also manyobservation group, proportionally to which smaller variations

factors. These factors fall broadly into two categories: the firstwill allow the detection of significant differences. It follows

relates to the mechanism of the occurrence of the target diseases

then that more minute changes can be detected with the increase

while the second indirectly relates to the occurrence of the target

in the size of the observation group. The objective of this study

diseases. When there is only one primary factor, analysis is

is to estimate the number of years of continuous observation

relatively easy. With more than one primary factor, the diseaserequired to detect significant increases from the currently

model will become complicated, making analysis difficult inavailable size of the observation group in this study.

1 ）
（ 39
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(Persons)Age (as of January 1, 2018)
Figure 1. Age distribution(Persons)

Dose during emergency work
Total dose

Figure 2. Dose distribution

B. Study methodology

disease with respect to the size of the observation group in an

The setting of the criterion for determining whether an

epidemiological survey of the emergency workers, theincrease in an observation result is random or significant isinvestigator must select a target disease of interest and calculate

arbitrary. There are, however, standard criteria defined

the expected number of occurrences. While this is the study

empirically. The usual practice is to determine an increase as

hypothesis per se, this report aims to estimate the size, andsignificant if the increase occurs only at a rate less than 5% (fivehence takes up the incidence of all cancers for which both thetimes per 100 times) or 1% for the distribution of a standard

incidence and mortality rates in Japan are available, as well asgroup (called "p-value"). In other words, these criteria

risks that have been estimated in the life span study of thedetermine an event as non-random (a significant increase) if it

atomic bomb survivors.

occurs only five times or once out of 100 times. Conversely, theThe size of the current target group is evidently too small for

rate at which the same determination criteria can determine thea cross-sectional comparison of a one-year track record. Thus,

distribution of the observation group correctly as such is called

it is decided to think in terms of cumulative total numbers anddetection power.

consider how many years of continuous observation and how

In order to evaluate the frequency of the occurrence of amany occurrences of the disease it will take to allow the

2 ）
（ 40
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determination. In order to calculate the expected number ofdoses are both registered in the MLHW long-term healthoccurrences of the target disease, the age-specific numbers ofmanagement system database. Figure 1 shows the age

individuals in the observation group over time during the

distribution of the 19,084 individuals as of January 1, 2018,

observation period will be necessary, along with the age-while Figure 2 shows the distribution of the dose during

specific ratios of incidence of the disease concerned for each

emergency work and that of the total dose. In the 20-50 mSv

year. Because both the age-specific populations and incidence

and 50-100 mSv ranges, the total dose applies to a larger

rates for each year in the future are unknown at this moment,

number of individuals than the dose during emergency work.

there is no choice but to simulate these values. In the simulation

One of the likely reasons is that many of these individuals have

performed this time, the age-specific populations werebeen engaged in some sort of radiation work after theestimated using a demographic model that assumed that the

emergency work period; another likely reason is that exposure

current age-specific populations would decrease every year atdue to engagement in radiation work is controlled not to exceed

the rate of the current age-specific number of deaths. Then, thethe dose prescribed under the Guidelines for Maintaining andexpected number of cases was estimated on the assumption that

Promoting the Health of Emergency Workers at Nuclear Powerthe current age-specific cancer incidence rates would continue

Facilities and the Ordinance on Prevention of Ionizingin the future.

Radiation Hazards.

Finally, the magnitudes of the increase in the risk for thisFigure 3 shows age-specific mortality rates for all causes ofgroup per radiation exposure of 100 mSv were expressed bydeath (2014), cancer incidence rates (2011), and cancer

relative risk (RR) levels and estimated for the following threemortality rates (2014) per population of 100,000 people inlevels: 1.1 (10% increase), 1.075 (7.5% increase), and 1.05 (5%Japan. This report assumes that these rates will remainincrease). As for exposure doses, the simulation used both theunchanged in the future. Figure 4 shows the cumulative"dose during emergency work" during the emergency work

expected number of occurrences of solid cancer for each follow-

period and the "total dose" consisting of the dose during theup period; a rapid increase will continue until approximately 40

emergency work and the dose recorded thereafter.

years later, after which the increase will gradually slow downwith the decrease in the remaining population.

C. Study results
The data for the calculation was provided by the 19,084

Mortality rate for all causes of death (per 100,000 people)(2014)

Cancer incidence rate (per 100,000 people)(2011)

Expected number of occurrences(cumulative)

Mortality rate/incidence rate (perpopulation of 100,000 people)

individuals whose doses during the emergency work and total

Cancer mortality rate (per 100,000 people)(2014)

Follow-up period

AgeFigure 4. Expected number of occurrences of cancer (cumulative)

Figure 3. Mortality rate/incidence rate in Japan

Expected excess incidence (cumulative)

Total dose

Total dose

RR per 100 mSv = 1.1

Total dose

Dose during emergency work

RR per 100 mSv = 1.075

Dose during emergency work
Total dose

RR per 100 mSv = 1.05

Dose during emergency work

Statistical detection power

Dose during emergency work

Follow-up period

RR per 100 mSv = 1.075
Dose during emergency work
Total dose
Dose during emergency work

Follow-up period

Figure 6. Statistical detection power

Figure 5. Expected excess incidence (cumulative)

2 ）
（ 41
−135−

RR per 100 mSv = 1.1

Total dose

RR per 100 mSv = 1.05

Figure 5 shows the expected cumulative excess incidence of

expected without assuming a considerably higher risk than thecancer (cumulative number of occurrences of cancer induced byabove value. In practice, however, cancer hardly develops due

radiation exposure) when assuming the three relative risks (RR)

to a single factor, and the stochastic contributions of its factors

levels of 1.1, 1.075, and 1.05 per 100 mSv to separately follow

would take various values. Hence, an assumption of theup the target population until 60 years later for the dose during

involvement of more than one contributory factor will

emergency work and the total dose. The expected excess

completely change the sample size estimation. In cases thatincidence increases with the increases in relative risk (RR) andrequire the correction of confounding factors, the required

exposure dose. Figure 6 shows the increases in statisticalnumber of samples will increase accordingly. Moreover, if thedetection power for when assuming relative risk (RR) levels of

disease model is intended to observe not a stochastic event but

1.1, 1.075, and 1.05 per 100 mSv. Even when assuming thethe change in the continuous quantity of all samples, successful

relative risk level as a 10% risk increase per 100 mSv (RR=1.1),

detection may be possible even with a small sample size. Thus,

which is higher than the average percentage observed among

the sample size simulation results presented herein must be

atomic bomb survivors (RR per 100 mSv = approx. 1.051), theunderstood as derived from the assumptions of a simplified

total dose-based calculation predicted that the usually intended

model. For this epidemiological survey, it matters most to callstatistical detection power of 80% would not be achieved until

out for all members of the given group to participate in this60 years later. A simulation of a 60-year-long follow-up study

study and then to continue observation of target individuals

based on the doses during the emergency work predicted thesteadily with their consent.

statistical detection power would not reach 70%.
F. Research publications
D. Discussions

1. Papers published in academic journals

This report has examined no more than a cancer incidence
model that assumes that the disease occurs or not andNone
2. Conference presentations

stochastically develops; hence, it differs from ones that deal

Nonewith events observable as analog quantities commonly among
all subjects, such as height, weight, blood pressure, or bloodbiochemical test values. Moreover, this report assumed that

G. Intellectual property rights acquired
None

only one factor contributes to the development of the disease.
In real workplaces, however, there are almost no diseases towhich only one factor contributes. If what needs to be done here
is to determine whether or not the disease is a prescribedindustrial disease to be covered by industrial accident
compensation insurance (on-duty vs. off-duty), the issue will bewhether or not the contribution ratio was 50% or more. Of
course, this is purely theoretical, and contribution ratios are■ References
1) Preston DL, Ron E, Tokuoka S, et al. Solid cancer incidence
in atomic bomb survivors: 1958-1998. Radiat Res, 168: 1-64,
2007.

extremely difficult to calculate precisely. In reality, there arealways confounding factors involved. In cases where theircorrection is necessary, it must be borne in mind that the sample
size must be increased to accommodate the correction.
E. Conclusions
On the assumption that there would be a follow-up study on
solid cancer incidence, this report estimated statistical detection
power. If the radiation exposure-induced cancer incidence
excess risk were considerably overestimated (10% increase for
100 mSv), a forty-year or longer follow-up of the entire target
population (approximately 20,000 individuals) would allow thedetection of solid cancer incidence risk with a statisticaldetection power of 80%. Accordingly, supposing that thepercentage of health checkup participants remains at the current
level of 35 to 40%, sufficient detection power cannot be

1 ）
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Industrial Disease Clinical Research Grants fromJapanese Ministry of Health, Labour and Welfare
Epidemiological Study on the Health Effects in Radiation Workers(Epidemiological Study of Health Effects in TEPCO Fukushima Daiichi Nuclear Emergency Workers)

The first period (FY2014 to FY2018)
Third Party Committee Report
Chairman Ginji Endo
June 2020
Publish:Headquarters of the Epidemiological Study on the Health Effects in Radiation Workers
Research Center for Prevention from Radiation Hazards of Workers
National Institute of Occupational Safety and Health, Japan (JNIOSH),
Japan Organization of Occupational Health and Safety
Nagao 6-21-1, Tama-Ku, Kawasaki 214-8585 Japan
TEL: +81-44-865-6111
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