保健医療科学

2018 Vol.67 No.1 p.21－33

Topics: Lessons learned on public health from the Fukushima Daiichi Nuclear Power Plant accident＜ Review ＞
Regulation values and current situation of radioactive materials in food
Hiroshi Terada1), Ichiro Yamaguchi1), Tsutomu Shimura1),
Erik R. Svendsen2), Naoki Kunugita1)
1)

Department of Environmental Health, National Institute of Public Health2)

Division of Environmental Health, Department of Public Health Sciences, Medical University of South Carolina
Abstract
After the Fukushima Dai-ichi Nuclear Power Plant accident, the Ministry of Health, Labour and Welfare
set the provisional regulation values for radioactive materials in foods by adopting Indices for Food andBeverage Intake Restriction. The indices were established based on 5 mSv of effective dose and 50 mSv
of committed equivalent dose to the thyroid in compliance with the recommendations of the International
Commission on Radiological Protection and others. On April 1, 2012, the present standard limits were put
in force for the exiting exposure situations. The standard limits were intended not to exceed 1 mSv/year
from food intake. One milli-Sievert per year of maximum permitted level conforms with the intervention
exemption level (reference level) adopted by the Codex Alimentarius Commission. The provisional
regulation values and the present standard limits of Japan are lower than the derived intervention levels of
the U.S., the EU and Codex.
Immediately after the monitoring of foods began, public concern was raised since many samples of leafy
vegetables and raw milk were found to be above the provisional regulation values. Thus, several publichealth protection measures were taken to decrease the concentrations of radioactive materials in foods by
the Ministry of Agriculture, Forestry and Fisheries, the local governments and the farmers, such as feeding
livestock with safe food and the application of potassium fertilizer. Due to these measures, almost all of
the marketed foods in Japan are below the standard limits and concentrations of radioactive cesium are
sufficiently low at this moment. Results of dose estimation with the monitoring data and total diet studies
also show committed effective doses from food are well below the maximum permissible level; thus, it canbe concluded that the measures taken by Japan after the Fukushima accident were reasonably successful.
However, there are still some foods found with radiocesium concentrations above the standard limit likewild mushrooms, wild animal meat, wild vegetables, freshwater fish, and some saltwater fish whose feedingor cultivation management are difficult to control. Thus, monitoring of those foods should be continued.
keywords: standard limit, provisional regulation value, radioactive cesium, dose estimation, total diet study(accepted for publication, 15th February 2018)

I．Introduction
Even before the Fukushima Dai-ichi Nuclear Power
Plant (FDNPP) accident, there existed regulatory values
for radioactive materials in foods, namely the interim limit
and Indices for Food and Beverage Intake Restriction(hereinafter referred to as "the indices") in Japan.

The interim limit was established for foods imported fromthe European region after the Chernobyl Nuclear Power
Plant accident [1]. The Ministry of the Health and Welfare
set the limit to 370 Bq/kg as a sum of the radiocesium
concentration (134Cs + 137Cs). Any lots of such foods thatexceeded the limit were recalled, reshipped or disposed ofCorresponding author: Hiroshi Terada
2-3-6 Minami, Wako, Saitama 351-0197, Japan.
Tel. +81-48-458-6263; Fax +81-48-458-6270; Email: terada.h.aa@niph.go.jp

J. Natl. Inst. Public Health, 67 (1) : 201821

Hiroshi Terada, Ichiro Yamaguchi, Tsutomu Shimura, Erik R. Svendsen, Naoki Kunugita
on the basis of the Food Sanitation Act [2].
On the other hand, the indices were established by the
Nuclear Safety Commission of Japan (NSCJ) to prepare fora radiological emergency situation. In accordance with theindices, the Nuclear Emergency Response Headquarters(NERHQ) would begin discussion on whether to adopt
restriction measures for intake of domestic foods andbeverages if a radiological event were to occur. Initially, theindex for 131I was set in 1980, and the indices for radioactive
cesium, radioactive strontium, plutonium, uranium andother alpha-emitting transuranic elements were set in lightof the Chernobyl Nuclear Power Plant accident and the JCO
criticality accident [3].
For these reasons, the indices were adopted as theprovisional regulation values (PRVs) for radioactive
materials in foods under the Food Sanitation Act after the
FDNPP accident, on March 17, 2011 [4]. The PRVs were
set so urgently by the Ministry of Health, Labour andWelfare (MHLW) that the MHLW requested that the Food
Safety Commission of Japan (FSCJ) assess the suitability of
the PRVs. In response to this request, the FSCJ concluded
that "the provisional regulation values established by
MHLW are based on and in line with such a bit too stringent
safety criteria" on March 29, 2011 [5]. However, because
there was a strong need for new radiological standards, thepresent standard limits were prepared by the MHLW and
put in force on April 1, 2012.
In this section, the following 3 topics will be reviewed:
basic concepts for establishing the PRVs and the present
standard limits, current situation of radioactive materials in
food, and estimation of effective dose from food consumption.

II．Basic concepts for establishing the PRVs
and the present standard limits
1. The provisional regulation values
The MHLW set the PRVs by adopting the indicesprepared by the NSCJ [4].
The NSCJ’s basic concepts for establishing the indiceswere as follows [6]:• The indices were not equivalent to the concentration
limits of the radioactive materials in foods which
represent the upper limit not to cause an adverse healtheffect, but the guidance levels to adopt restriction
measures for food and beverage intake as low as isreasonably achievable for radioprotection.
• Five mSv of effective dose and 50 mSv of committed
equivalent dose to the thyroid were adopted as the upper
level of the intervention dose levels in compliance withthe recommendations of the International Commission
on Radiological Protection (ICRP), International Atomic

22

Energy Agency (IAEA) and others [7,8].
Radioactive materials concentrations in foods
corresponding to the intervention dose levels (hereinafterreferred to as DILs from "derived intervention levels")
were derived on the basis of the following requirements:
1) radioactive iodine, radioactive cesium and strontium,
plutonium and alpha emitting transuranic radionuclides,
and uranium were taken into consideration, 2) foods weregrouped into five categories (drinking water, milk and dairy
products, vegetables, grains, and others), 3) for radioactive
cesium, an annual dose of 1 mSv was assigned to eachfood group, 4) radioactivity ratio of 90Sr to 137Cs in theenvironment was assumed to be 0.1, 5) for the long-lived
radionuclides, the average concentrations of contaminatedfoods were assumed to be half of the peak concentration,
whereas a dilution factor of 1 was applied for short-lived
radionuclides. More details on the derivation of DILs were
described by Suga et al. [6], Hamada et al. [3] and Inaba [9].
The indices were obtained by rounding down the DILs.
For instance, the DILs for radioactive cesium in milk was
induced at 270 Bq/kg, then later the indices of radioactive
cesium in milk was set to 200 Bq/kg. The RPVs forradioactive cesium were shown in Table 1. They were set to
200 Bq/kg for drinking water, and milk and dairy products,
and 500 Bq/kg for vegetables, grain, meat, eggs, and fish.
For radioactive iodine, the indices were set to 300 Bq/
kg for drinking water, milk and other dairy products, and
2,000 Bq/kg for vegetables (other than root vegetables andpotatoes which were considered much less contaminatedwith radioactive iodide than other vegetables). Therefore,
the indices were not given for root vegetables and potatoes.
For the similar reason, grain, meat, eggs, and fish also were
not given the indices for the short-lived radioactive iodide.
On the contrary, high levels of radioactive iodine which
exceeded the PRVs for vegetables were detected in fish after
the FDNPP incident. In response to this issue, the MHLW
decided to adopt a PRV of 2,000 Bq/kg for radioactive iodine
in fish and fishery products on April 5, 2011 [10].
The PRVs were followed by food safety policies basedon the Food Basic Safety Act in an emergency situation.
According to an immediate report to the MHLW, the FSCJ
stated that “the thyroid equivalent dose of 50 mSv per year
was concluded, at the present situation, to be sufficiently
safe for prevention of radiation”, and as regarding
radioactive cesium, “the annual effective dose of 5 mSv wasconsidered as highly conservative”, on March 29, 2011 [11].
But they also stated in this report that “It should be clearly
heeded that this emergency report is not appropriate
as a basis for risk management measures under normal
circumstances” [11].

J. Natl. Inst. Public Health, 67 (1) : 2018and current
situationof radioactive
materials
food adopted
Table 1 Regulation
Derived values
Intervention
Levelsfor radioactive
materials
in infoodsby the United States, the European Union, the Codex Alimentarius Commission

Table 1 Derived Intervention Levels for radioactive materials in foods adopted by theand Japan
United States, the European Union, the Codex Alimentarius Commission andJapan

Food category

USA 1)EU 2)

CAC 3)

Unit (Bq/kg)
Japan
Provisional regulatory
Present
values 4)
standard limits

Drinking water

1,200

1,000

1,000

200

10

Milk

1,200

1,000

1,000

200

50

General Foods

1,200

1,250

1,000

Infant foods
Intervention
level5)Fraction of foodaffected

1,200

400

100

500

1,000

50

5 mSv
/year

1 mSv
/year

1 mSv
/year

5 mSv/year

1 mSv/year

30%

10%

10%

50%

50%

1) Accidental Radioactive Contamination of Human Food and Animal Feeds: Recommendations for State
and Local Agencies
2) Council Regulation (Euratom) 2016/52 of 15 January 2016 laying down maximum permitted levels of1)radioactive
ACCIDENTAL
RADIOACTIVECONTAMINATIONOF HUMANFEEDS:
contaminationof food andfeed following a nuclear
accidentFOOD
or any AND
other ANIMAL
case of radiologicalemergency,
andrepealing
Regulation(Euratom)No3954/87
andCommission
Regulations(Euratom)
RECOMMENDATIONS FOR STATE AND LOCAL AGENCIESNo 944/89 and (Euratom) No 770/90
2)
Council
Regulation(Euratom)
2016/52 ofJanuary
2016 andlayingdown
maximum
permitted levels
3) Codex
in Food
Feed(CodexStan 193-1995)
GeneralStandard
for Contaminants
and15Toxins
were4) Foods
groupedinto
thefollowing
5
categories:(1)
drinking
water,
(2)
milk
and
dairy
products,of radioactive contamination of food and feed following a nuclear accident or any othercase (3)ofvegetables, (4) grains, (5) meat, egg, fish and the others.
radiologicalemergency,
andrepealing
Regulation(Euratom)No3954/87
andCommission5) For radionuclides in foods, WHO proposed 5 mSv/y for emergency exposure situation and IAEA
indicated 1mSv/y for existing exposure situation as reference levels.
Regulations (Euratom) No 944/89 and (Euratom) No 770/90

3) CODEX GENERAL STANDARD FOR CONTAMINANTS AND TOXINS IN FOOD AND FEED

2. Present standard(CODEX
limits STAN 193-1995)
foods. The basic concepts for establishing the limits were
The FSCJ finally submitted the “Risk Assessment
described below.
4) Foods were grouped into the following 5 categories: (1) drinking water, (2) milk and dairy products,
Report on Radioactive Nuclides in Foods” to the MHLW on(1) Target radionuclides(3) vegetables, (4) grains, (5) meat, egg, fish and the others.
October 27, 2011. This report concluded that:
The present standard limits were put in force in April
5) For radionuclides in foods, WHO proposed 5 mSv/y for emergency exposure situation and IAEA
• Cumulative effective doses more than around 100 mSv
2012, more than 1 year after the FDNPP accident. Thus,
indicated
1mSv/yexisting exposure
as reference
levels. radioactive materials including 134Cs, 137Cs,: cumulative effective
doses
of forradiation
during situationthethe long-lived
106
Ru, 238Pu, 239Pu, 240Pu and 241Pu were selected as the target
lifetime could increase the risk of the effect on health.
radionuclides. Radioactive iodine was not considered due
The amount does not include radiation from the natural
to its short half-life. These remaining nuclides were placed
environment and medical exposure.
on the trial calculation list of the Nuclear and Industrial• Babies, infants and children are considerably more
Safety Agency (NISA) as substances emitted by the FDNPP
susceptible to radiation than adults, posing a possibility ofaccident. Uranium was not chosen as a target radionuclide
developing thyroid cancer and leukemia.
since there was no significant change between the nuclear• Although some epidemiological studies indicate thepower plant site compared to other environment.
potential health hazard by exposure of radiation doses(2) Food Categories
at levels below 100 mSv, there exist many uncertainties
Foods were classified into 4 categories (drinking water,
regarding their data reliability [12].
infant foods, milk, and general foods). Drinking water, infant
As a risk manager, the MHLW decided that new
food and milk were chosen as different categories for theradiological standards for foods in the existing exposure
following reasons: 1) There was no substitution for water,
situation were based on 1 mSv/year as the maximum
its consumption is large and it is a requirement for humanpermissible dose due to food consumption. This maximum
life, 2) the FSCJ pointed out that “It should be noted that
permissible dose fulfills the FSCJ’s conclusion andchildren are considerably more susceptible to radiation thanconforms with the intervention exemption level (reference
adults”.
level) adopted by the Codex Alimentarius Commission
Other foods above were categorized as “General Foods"(CAC), which is an intergovernmental body established byfor the following reasons: 1) it makes the influence of
the Food and Agriculture Organization and the World Healthindividual differences in eating habits (deviation of theOrganization (WHO) [13]. Then, the MHLW preparedfoods to be consumed) minimal, 2) makes the regulations
the present standard limits for radioactive material in

J. Natl. Inst. Public Health, 67 (1) : 201823

Hiroshi Terada, Ichiro Yamaguchi, Tsutomu Shimura, Erik R. Svendsen, Naoki Kunugita
intelligible for common people, 3) it is consistent withinternational organizations, such as the CAC.
(3) Age and sex
The standard limits for regulation of radioactive materials
in general foods were set by taking age differences in foodconsumption into consideration. The difference in theamount of food intake between the sexes was taken into
considerations except for the age category of less than
1 year old. Pregnant women were also given a separate
category. There are five age categories (less than 1 year old,
1 to 6 years old, 7 to 12 years old, 13 to 18 years old, and 19
years old or older) in male and female. As a result, a total of
10 categories were used.
(4) Standard limit for drinking water
According to the WHO's guidelines, the guidance level of
10 Bq/kg for radioactive cesium was adopted as a standard
limit for drinking water [14]. Annual dose from drinking
water was calculated to be approximately 0.1 mSv/year
by using the standard intake rate for drinking water (2liters/day) estimated by the WHO and the standard limit
mentioned above.
(5) Contribution of radionuclides other than radioactive
cesiumRadionuclides other than 134 Cs and 137 Cs are notsuitable as indices for routine monitoring because of
the requirement of longer measurement times. Thus,
the contribution of radionuclides other than radioactive
cesium to the effective dose was estimated from the initialratio of the concentration and the transfer factor of eachradionuclide according to the transfer pathway from its
origin to human consumption (e.g. from soil to crops, crops
to human; from fresh water to freshwater fish, freshwater
fish to human; and so forth) [15]. The initial ratio of theradionuclide concentration was obtained from monitoringdata of soil and rivers [16-18] and the trial calculation listof the NISA [19]. For instance, the contribution of these
nuclides was estimated to be about 12% in the case ofpeople aged 19 and older.
(6) The fraction of affected foodOn the basis of monitoring results and the food selfsufficiency rate of Japan, it was assumed that 50% of foods
distributed were affected. Therefore, the standard limits
were set so that the effective dose of the most vulnerable
age group was expected to be below 1 mSv/year, even if asmuch as 50% of the foods were at the limit value. As formilk and infant food, it was conservatively assumed that
all the distributed foods are affected since those foods aremostly produced in Japan and “During childhood people areconsiderably more susceptible to radiation than adults” [12].
(7) Determination of the standard limits
Fig. 1 shows the concept of the limit for general foods.

24

Annual effective dose from drinking water was calculated tobe approximately 0.1 mSv/year as described above. Thus,
effective dose from foods other than drinking water should
be below 0.9 mSv in order not to exceed the maximum
permissible annual dose (1 mSv/year). Radioactive
materials concentrations in general foods corresponding to
0.9 mSv were derived on the basis of the dose coefficientsand food intakes according to age and sex. As shown in Fig.
1, the minimum derived concentration was 120 Bq/kg forthe category of 13 to 18 years old males. The standard limit
for general foods was set to be 100 Bq/kg by rounding down
the minimum derived concentration. The standard limits formilk and infant foods were set to be 50 Bq/kg, because allof these foods were assumed to be affected with maximum
levels of radioactive materials concentrations. More details
on derivation of the standard limits were described by
Iwaoka [15].
Unit: Bq/kg

1 mSv
/year

0.9 mSv
/year

Age

Sex

Derivedconcentration

under 1

Average forboth sexes

460

Male

310

1-6
7-12
13-18

0.1 mSv/year(Drinking water)

19 and older
pregnant

Female

320

Male

190

Female

210

Male

120

Female

150

Male

130

Female160

Female160

MinimumStandard
Limit
100
Bq/kg

120

Fig. 1 Induced limits of general food for each age category(8) Comparison with USA, EU and CAC
The DILs for radioactive materials in each food category
are shown in Table 1. The United States, the European
Union and CAC adopt DILs for general foods at 1,200 Bq/
kg, 1,250 Bq/kg, 1,000 Bq/kg, respectively [13, 20, 21]. Theintervention levels of 1 mSv per year are set in the EU
and CAC as well as the standard limits of Japan [13, 21].
On the other hand, Protective Action Guides (PAGs) of 5
mSv for committed effective dose or 50 mSv for committed
equivalent dose to an individual tissue or organ are used in
the USA, as in the same manner with the PRVs of Japan [20].
The difference in the values of DILs mainly causes from
distribution ratio of food intake assumed to be affected.
Japan conservatively assumed that 50% of foods distributed
were affected as described before, while it was assumed
that 10% of the dietary intakes were affected by the EU and
CAC [13, 21]. As for the U.S., an additional factor of three
was applied to account for the fact that sub-populations
might be more dependent on local food supplies [20].

J. Natl. Inst. Public Health, 67 (1) : 2018

Regulation values and current situation of radioactive materials in food

III．Current situation of radioactive materials in foodi.e., a detailed monitoring and an efficient screening
test. As a detailed monitoring, radionuclide analysis isconducted using a germanium semiconductor detector.
For an efficient screening test, an NaI (TI) scintillation
spectrometer is used. An NaI scintillation spectrometeris inferior to a germanium semiconductor detector interms of measurement accuracy, but can shorten thetime required for the monitoring and is cheaper. If themeasurement using an NaI scintillation spectrometersuggests the existence of radioactive cesium exceeding
the standard limits, a monitoring is conducted again using
a germanium semiconductor detector [24]. Adding to this,each municipality provides a food monitoring service to its
residents.
The monitoring results are compiled by the MHLW, andthe compiled data are released on its website weekly [25].
On this website, the monthly reports written in English arealso available. And there exists a searchable site regarding
the monitoring results of the radioactive materials in foods
managed by the National Institute of Public Health (NIPH)[26]. Users can search based on the production area or
the item name, or search through designating detailed
conditions and can also refer to information on shipping
restrictions on this website.

1. Monitoring of radioactive materials in Foods
Af ter the FDNPP accident, the guideline for themonitoring of radioactive materials in foods was establishedby the Nuclear Emergency Response Headquarters(NERHQ) on April 4, 2011 [22]. In this guideline, the items
subject to monitoring and the frequency of monitoring were
designated. The guideline was reviewed annually by the
NERHQ in light of the monitoring results (latest revision:
March 24, 2017) [23].
Any lot of such foods that exceeded the standard values
shall be recalled or disposed of based on the Food Sanitation
Act. If affected areas are found to be extended, the shipping
restrictions will be issued by designating the areas anditems based on the Act on Special Measures Concerning
Nuclear Emergency Preparedness. The restrictions would
not be lifted until the monitoring results confirm thatthe concentrations of radioactive materials are below thestandard values.
The monitoring for this purpose is mainly implemented
by the local governments and focused especially on
the items that are likely to contain higher levels ofradioactive cesium. There are two ways to monitor foods,

Table
onitoring results
resultsforfor
radioactive
materials
Table22 MMonitoring
radioactive
materials
in foodsin foods
collected
by
March
of
2012
collected by March of 2012
Food category

Number of tests

Number of violations

Vegetable

21,121

451

Fishery Products

9,408

245

Milk·Dairyproducts

2,991

23

Meat·Egg

94,155

286

Grain

5,553

2

Others3,808

197

Subtotal

137,036

1,204

Table3 3M onitoring
Monitoring
resultsforforradioactive
radioactive materials
materials inin foods
foods
results
Table
collectedcollected
after setting
limits on limits
April 1,afterpresent
settingstandard
present standard
on 2012,April by1,
January2012,
23, 2018
by January 23, 2018
Food category

Number of tests

Number of violations

Agricultural products

206,384

1,242

Livestock products

1,424,202 (1,413,999)*

4 (2)*

Fishery products

122,728

1,509

Milk·Infant foods

23,5720

Wild animal meat

7,967

1,898

Drinking water

5,046

13

Others55,814212

Subtotal

1,845,713

4,878* Number of beef sample was shown in parenthesis.

J. Natl. Inst. Public Health, 67 (1) : 201825

Hiroshi Terada, Ichiro Yamaguchi, Tsutomu Shimura, Erik R. Svendsen, Naoki Kunugita
2. Monitoring results on the radioactive materials infoods
Approximately two million tests of radioactive materials
in foods have been conducted as of January 23, 2018. The
tests results are shown in Table 2 and 3. Tables 2 lists theresults of the samples collected by March 31, 2012, namely
based on the PRVs. The PRVs were exceeded in 1,204
samples out of 137,036.
Table 3 lists the results of the samples collected after
April 1, 2012. The standard limits were exceeded in 4,878
samples out of 1,845,713. About three fourths of thesamples was beef and the vast majority of the tests (92%)
were done before shipment. The violation rate for all of
the samples was 0.26%. Those of the foods other than beef
before shipment and after shipment were 1.6%, 0.051%,
respectively.
The results of representative items were described
below.
3. Leafy vegetables
During the early stage of the FDNPP accident,
radioactive iodide or cesium exceeding the PRVs weredetected in many samples of leafy vegetables. In fact, thehighest concentration of radioactive iodide and cesiumin all of the samples were found in a spinach sample at
54,100 Bq/kg, and Brassica leafy vegetable at 82,000 Bq/
kg, respectively. Shipment of those vegetables was thenrestricted in Fukushima Prefecture, Ibaraki Prefecture,
Tochigi Prefecture, Gunma Prefecture (since March 21),and Chiba Prefecture (since April 4, 2011). However, theconcentrations of these radionuclides in leafy vegetables
decreased rapidly as shown in Fig. 2. Shipping restrictions
were lifted in Ibaraki Prefecture, Tochigi Prefecture,
Gunma Prefecture and Chiba Prefecture by June, 2011.
The restrictions were also lifted in Fukushima Prefecture,
except for Futaba Town and areas where habitation isdifficult in Minamisoma City, Tomioka Town, Okuma Town,
Namie Town, Katsurao Village and Iitate Village [27]. At
this moment, radioactive cesium is not detected in almost
all samples of leafy vegetables.
4. Raw milk
Immediately after the food monitoring began, raw milk
samples which exceeded the PRVs were found. Therefore,
the Ministry of Agriculture, Forestry and Fisheries(MAFF) issued the following notifications to the prefectural
governments:• Notification to prefectures in the vicinity of the nuclear
station of precautions regarding feed, water, feeding
locations, etc (on March 19, 2011) [28]• Notification of the standards for radioactive materials

26

in feed to ensure that produced meat and milk does notexceed the provisional regulation values stipulated in the
Food Sanitation Act (on April 14, 2011) [29]• Notification of a guideline on the production andutilization of feed for avoiding radioactive contaminationof beef cattle and milk (on April 22, 2011) [30]
As a result, none of the raw milk samples exceeded thePRVs or the standard limit since March 23, 2011. Shipping
restrictions of raw milk were imposed in Fukushima
Prefecture and Ibaraki Prefecture on March 2011, but
the restrictions have already been lifted other than thefollowing areas: Minamisoma City, Kawamata Town,
Tomioka Town, Okuma Town, Futaba Town, Namie Town,
Katsurao Village and Iitate Village [27].
5. Beef
Regardless of the notifications mentioned above, samples
of beef cattle containing radioactive cesium above the PRV
were found on July 8, 2011. Soon afterward, rice straw
was found highly contaminated with radioactive cesium,
and identified as the cause. It was revealed that many
beef samples which exceeded the PRV were distributedin the market. Therefore, the MAFF set the provisional
tolerable values for feed including rice straw [31], and the
MHLW issued a request to local governments concerned
to implement surveys on beef distribution channels, toensure that beef that exceeded the PRVs was not put into
circulation [32]. In addition, some local governments havebegun to monitor radioactive cesium in beef for all cattle
shipped to the slaughterhouses. Though no beef sample
exceeded the standard limit since October 26, 2012 and thevast majority were below the detection limit (Fig. 2), suchmonitoring still continues. Thus, efficiency of continued
monitoring was discussed by Shimura et al [33].
Rice straw was not fed to chickens and pigs because theycannot digest it. Furthermore, almost all their feed wasimported from outside of Japan. Thus, no chicken sample
violated the PRV or the standard limit. With regard to pork,
only one sample exceeded the standard limit.
6. Rice
Until now, 116 rice samples were above the PRV or
the standard limit. However, no rice sample exceeded thestandard limit since July 13, 2015.
Safety of rice is ensured through restricting planting,taking measures to inhibit radiocesium absorption
by application of potassium fertilizer and conducting
postharvest inspections, etc. In addition, all bags of brownrice produced in Fukushima Prefecture have been tested
since 2012, ten million samples annually. The tests results
are not contained in Table 3 because the tests are apart

J. Natl. Inst. Public Health, 67 (1) : 2018

Regulation values and current situation of radioactive materials in foodSpinach

10000
1000
100

provisional regulatory value
standard limit

101

100000radiocesium concentration

Iodide-131 concentration

1000000.1

Spinach

10000
1000
100

provisional regulatory value
present
standard
limitstandard limit

10
1
0.1

Mar 2011 Jul 2011 Nov 2011 Mar 2012

Mar 2011 Mar 2013 Mar 2015 Mar 2017

sampling month

Beef

10000
1000

provisional regulatory value

100

present
standard
limit standard limit

101

100000radiocesium concentration

radiocesium concentration

100000sampling month

0.1

10000
1000
100

10
1
0.1

Mar 2011 Mar 2013 Mar 2015 Mar 2017

Mar 2011 Mar 2013 Mar 2015 Mar 2017

sampling monthsampling month
100000

1000
100

10
1
0.1

Wild animal meat

Mar 2011 Mar 2013 Mar 2015 Mar 2017

radiocesium concentration

radiocesium concentration

100000
10000

Mushroom

10000

Fishery products

1000
100

10
1
0.1

Mar 2011 Mar 2013 Mar 2015 Mar 2017

sampling monthsampling monthunit: Bq/kg

Fig. 2 Radiocesium and Iodide-131 concentrations in foods after Fukushima nuclear power plant accident
The open circle symbols represent the maximum concentration for each month. The square symbols, the triangle symbols, the X mark andthe cross symbols represent 95th percentiles, median, 5th percentiles, minimum, respectively. The solid lines, broken lines correspond thepresent standard limit and the provisional regulatory values for radioactive materials in foods, respectively.

J. Natl. Inst. Public Health, 67 (1) : 201827

Hiroshi Terada, Ichiro Yamaguchi, Tsutomu Shimura, Erik R. Svendsen, Naoki Kunugita
from the ones based on the NERHQ’s guideline. The
results of all bags tests can be obtained on the websiteof the council for ensuring the safety of foods producedin Fukushima Prefecture [34]. According to this website,no bag exceeded the standard limit since 2015. In light ofthese results, Fukushima Prefecture decided to switch in
the near future to monitoring by random sampling of rice inaccordance with the NERHQ’s guideline [35].
7. Mushrooms
As shown in Fig. 2, the concentrations of radioactive
cesium in mushrooms are still high. In particular, 440
samples of shiitake mushroom exceeded the PRVs or the
standard limit. The MAFF established provisional safety
standards for mushrooms logs and beds wherein mushroom
fungi are planted [36]. Since FY2014, only 10 samples ofshiitake mushrooms violated the standard limit. Thus,
cultivated mushrooms can be controlled not to exceed
the standard limit by proper radiological protection andmanagement. On the other hand, wild mushrooms are
difficult to control, so that they should be continuously
monitored. Shipping restrictions of wild mushrooms arestill imposed in some regions of 12 prefectures (Fukushima,
Aomori, Iwate, Miyagi, Ibaraki, Tochigi, Gunma, Saitama,
Chiba, Yamanashi, Nagano and Shizuoka) [27].
8. Wild animal meat
Wi l d a n i m a l m e a t h a s t h e h i g h e s t r a d i o c e s i u mconcentrations compared to other foods. As shown in Fig.
2, median of their concentrations were above the standard
limit until FY2012 and violation rates were much higher
than those of other foods (Fig. 3). Even now, radiocesium
concentrations above 10,000 Bq/kg were detected in theirmeat. Shipment of their meat remain restricted in some50

violation rate (%)

40
30
20
10
0
Mar 2011 Mar 2012 Mar 2013 Mar 2014 Mar 2015 Mar 2016 Mar 2017
sampling month

Fig. 3 V i o l a t i o n r a t e s o f re g u l a t o r y v a l u e s f o r
radioactive materials in foods by month
The open circle symbols, the square symbols, the triangle
symbols, the X mark and the cross symbols represent wild animal
meat, mushrooms, fishery products, beef, spinach, respectively.

28

regions of 10 Prefectures (Fukushima, Iwate, Miyagi,
Yamagata, Ibaraki, Tochigi, Gunma, Chiba, Niigata andNagano) [27].
9. Fishery products
The concentrations of radioactive cesium in fisheryproducts decrease gradually as shown in Fig. 2. Since
September 2012, the 95th percentile of radiocesium
concentrations was below the standard limit. The numbersof the fish samples above the standard limit are as follows:
253 (FY2011), 1,072 (FY2012), 301 (FY2013), 100(FY2014), 14 (FY2015), 11 (FY2016), 11 (FY2017). Since
April 2015, no ocean fish exceeded the standard limit.
At the current moment, some freshwater fish such as achar, Oncorhynchus masou (kind of trout) were above thelimit in Fukushima Prefecture, Tochigi Prefecture, Gunma
Prefecture, Chiba Prefecture.
After the FDNPP accident, coastal and trawl fishingwere banned in Fukushima Prefecture. However, thesafety of certain species of fish has been confirmed by trial
monitoring inspections. Since April, 2017, the scope of trial
fishing has been extended to all species of fish and shellfish
except fish species under the shipment ban (10 species). Allfish produced from the trial fishing undergo monitoring forradioactive materials.

IV．Estimation of effective dose from foods
To evaluate the effectiveness of the measures described
before, dose estimation due to food consumption has been
attempted by various methods. One of them was dose
estimation based on the monitoring data of radioactive
materials in food published by the MHLW. The Radioactive
Material Response Working Group in the Food Sanitation
Subcommittee of the Pharmaceutical Affairs and Food
Sanitation Council reported such dose estimation resultson October 31, 2011 using monitoring data collected
immediately after the accident up to September, 2011.
Adding to this, the effective dose and thyroid equivalentdose integrated up to December 2012 from immediately
after the accident were reported by Yamaguchi et al [37].
The method for estimation was described below. A foodmonitoring dataset provided by the MHLW was used
for this study. The dataset reflects the concentrations ofradioactivity in food from Fukushima and 16 neighboring
prefectures. Each sample was pre-treated according to
the manual and was measured at 'ready to cook' status.
Concentrations of non-detected samples were set to be
the detection limits for each measurement or 10 Bq/kg for
131
I, 134Cs and 137Cs, respectively. When 60% of samples
of a food category (total n= 99) were below the detection

J. Natl. Inst. Public Health, 67 (1) : 2018

Regulation values and current situation of radioactive materials in foodTable 4 Effective dose from foods
medianCommitted
equivalentdose tothyroid
Committed
effectivedose

95th percentile

Age

1-6y

7-12

13-18

19-

1-6

7-12

13-18

Sex

Male

Male

Male

Male

Male

Male

Male

19MaleNo regulation 1)

6.00

3.16

2.09

1.04

21.39

8.91

7.80

5.43

Apply PRV 2)

1.72

0.90

0.77

0.49

4.57

1.88

1.75

1.31

Apply present standard limit 3)

1.71

0.90

0.76

0.49

4.57

1.88

1.75

1.30

No regulation

0.40

0.29

0.30

0.24

1.20

0.63

0.72

0.64

Apply PRV

0.16

0.14

0.19

0.17

0.33

0.22

0.31

0.30

Apply present standard limit

0.16

0.14

0.19

0.17

0.33

0.22

0.31

0.30

1) calculated on the assumption that foods exceeding the standard limits or the PRVs are distributed2) calculated on the assumption that marketed foods do not exceed the PRVs
3) calculated on the assumption that marketed foods do not exceed the standard limits

limits during a month, concentrations in the food category
were set to be half of these values for that month. When
80% of samples of a food category were below the detection
limits during a month, concentrations in the food category
were set to be quarter of these values for that month. The
unmonitored food category concentrations were assumed
to be 0 Bq/kg. The non-detected food sampled after June
2011, 131I concentration was assumed to be 0 Bq/kg. It was
assumed that 10 grams of tealeaves were used for 500 ml of
tea and the concentration of cooked rice was assumed to be
1/4 of the concentration of brown rice due to the polishingeffect. Food consumption in each 99 food categories wasmade available by using the original data of the Japanese
National Food Consumption Survey, which was conducted
in 2010 [38]. Food concentration and food consumptionin each category were randomly picked up (N=100,000)
every 4 days during first two months then every month byusing random sampling. The levels of radioactive iodine
and cesium were summed and then converted to theeffective doses in each month. The values of the ingestion
dose coefficients used for equivalent doses to the thyroid
were taken from the ICRP Database [39]. The results wereshown in Table 4. The estimated committed effective doseby age group derived from the radioiodine and radiocesiumin food after the FDNPP accident showed the highest
median value (0.19 mSv) in 13-18 years age. The highest
95th percentile value, 0.33 mSv, was shown in age group
1-6 years of age up to December 2012, showing the benefitsof the food safety management activities after the accident.
Dose estimation due to food consumption were also
attempted by the total diet studies (TDS) and the wholebody counter (WBC) survey. In the TDS, daily intake ofradioactive materials via foods are calculated with theconcentrations of radioactive materials in the food samples
and food consumption. Contrary to the TDS, the WBC

Committed effective dose（μSv）

Yamaguchi I., Terada H., Kunugita N., Takahashi K. Dose estimation from food intake due to the Fukushima
Daiichi nuclear power plant accident. J. Natl. Inst. Public Health. 2013; 62(2): p.138-143. (in Japanese)

20

Sendai City
Fukushima City

15

Tokyo

10
5
0

2011

2012

2013

2014

Year

Fig. 4 C ommitted effective dose from radiocesium
Fig. 4 Committed effective dose from radiocesium after
afternuclear
Fukushima
nuclearpower plant accident
Fukushima
power plant
accident
2011: results obtained by market basket method
2011: results obtained by market basket method
2012~2014: results obtained by duplicate portion method
2012~2014: results obtained by duplicate portion method

survey can measure the amounts of radioactive materials inthe body directly.
After the FDNPP accident, the TDS were conductedby Harada et al. [40], Sato et al. [41], the NIPH [42], theNational Institute of Health Sciences (NIHS) [43] and soon. Harada et al. performed the TDS for the residents of 3
regions (Fukushima Prefecture, Kanto, western Japan) on
December, 2011. Their results showed estimated dose level
was in the range of <2.6–99 μSv/year [40]. Similar results
were obtained by Sato et al. who conducted the TDS for the
residents of Fukushima Prefecture from November 2011 toMarch 2012 and from June 2012 to September 2012 [41].
The TDS by the NIPH was performed for the residents of
15 regions in Japan from FY 2012 to FY2014 [42]. Fig. 4
shows the results of 3 cities (Fukushima, Sendai, Tokyo). In
FY2014, the highest committed effective dose among the
3 cities was 0.89 µSv, equals up to 0.09% of the maximum
permitted level due to foods (1 mSv). In our studies,radioactive strontium and plutonium which are not targetsof the routine monitoring were also examined. The results

J. Natl. Inst. Public Health, 67 (1) : 201829

Hiroshi Terada, Ichiro Yamaguchi, Tsutomu Shimura, Erik R. Svendsen, Naoki Kunugita
suggest that concentrations of those radionuclides were
within the range of before the FDNPP accident. Similar
results were found by the NIHS [43].
The WBS surveys were conducted by Tsubokura et al.
Their results also suggested that annual additional effective
dose from internal radiation exposure of Fukushimaresidents were below 1 mSv and consistent with estimation
by WHO and United Nations Scientific Committee on the
Effects of Atomic Radiation (UNSCEAR) [44-48].
According to Sugiyama et al., committed effective doses
from radioactive cesium were below 0.4 μSv before the
FDNPP accident [49]. Though the internal doses are still
higher than before the accident, we can conclude thatcommitted effective doses due to food consumption are
estimated to be sufficiently below the maximum permissiblelevel and that measures taken by the Government of Japanafter the FDNPP accident were reasonably successful fromthe results described above.

V．Conclusion
The FDNPP accident was the second severest nuclear
disaster ever. However, almost all of the foods other thanwild mushrooms, wild animal meat, wild vegetables,
freshwater fish, and some saltwater fish are below thestandard limits. Furthermore, committed effective doses
due to food consumption are estimated to be sufficiently
below the maximum permissible level. Thus, it can beconcluded that measures taken by the Government of Japanafter the FDNPP accident were reasonably successful. The
lessons learned from the experience of the FDNPP accident
will help responses to future nuclear disasters.

Acknowledgements
This study was partially supported by special researchfunding from the Japanese Ministry of Health, Labour, andWelfare.

Conflict of Interests
The authors declare that there is no conflict of interests
regarding the publication of this article.

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Regulation values and current situation of radioactive materials in food

食品中の放射性物質の規制値と濃度の現状
寺田宙 1)，山口一郎 1)，志村勉 1)，エリック・スベンソン 2)，欅田尚樹 1)1)

国立保健医療科学院生活環境研究部

2)

サウスカロライナ医科大学公衆衛生科学部環境保健分野

抄録
福島原発事故後，厚生労働省は原子力安全委員会の策定した飲食物摂取制限に関する指標を基に食品中の放射性物質に関する暫定規制値を設定した．飲食物摂取制限に関する指標は国際放射線防護委員会等の考え方を踏まえて実効線量5 mSv ，甲状腺等価線量50 mSv を基準に策定されたものである．平成24年 4 月1日には現行の食品中の放射性物質に係る基準値が施行された．基準値は食品摂取による年間線量が 1 mSvを超えないように設定されており，コーデックス委員会の考えを踏襲している．日本の暫定規制値と基準値は米国，EU，コーデックスの誘導介入レベルよりも低くなっているが，これは基準となる線量ではなく，基準値の誘導にあたっての前提条件の違いによるものである．
事故後，食品の検査が始まると間もなく暫定規制値を上回る食品が見つかり大きな社会問題となった．このため，農林水産省，地方自治体と生産者により飼養管理の徹底，カリウム肥料の施肥といった様々な放射性物質の低減策が取られた．これらが功を奏し，現時点では大部分の食品は基準値を下回り，放射性セシウム濃度は十分低いレベルにある．食品の検査結果を用いた線量評価やトータル
ダイエットスタディにおいても食品由来の線量は年間線量の上限である 1 mSvを十分に下回っており，
我が国の事故後の対応は概ね有効であったと評価できる．
ただし，野生キノコ，野生鳥獣肉，山菜類，淡水魚といった飼養管理，栽培管理が困難な食品については依然として放射性セシウム濃度が高く，現時点でも基準値の超過が認められており，引き続きモニタリングを行うべきである．
キーワード：基準値，暫定規制値，放射性セシウム，線量評価，トータルダイエットスタディ

J. Natl. Inst. Public Health, 67 (1) : 201833