Forsionpt

secure fish conndsuamafe

Facts onmonitoringof radioactivity
in fish2023

Fisheries Agency of Japan

Preface
Twelve years have passed since the Fukushima Daiichi Nuclear
Power Station accident.
The Fisheries Agency has continued to inspect and publish theconcentration of radiation in seafood since the accident toensure its safety. This brochure explains that the concentrationof radioactive cesium in seafood has dropped significantly, andalso describes the tritium analysis that began in fiscal 2022.

1

Table ofContents

Preface ................................................................................. 1
Table of Contents ............................................................... 2
Structure of the monitoring for radioactive cesium in food 3
Framework of the monitoring ................................................ 3
Process of the laboratory test ................................................ 4
Finding from the results of the monitoring
Concentration of radioactive cesium in marine fish species
Results of the analysis of radioactive cesium in marine fish
species ................................................................................. 5
Changes in radioactive cesium concentration in marine fish
species ................................................................................. 6
Concentration of radioactive cesium in freshwater fish
speciesResults of the analysis of radioactive cesium in freshwater fish
species ................................................................................. 7
Changes in radioactive cesium concentration in major
freshwater fish species ......................................................... 8
ALPS Treated Water and Tritium Testing
What is ALPS Treated water? ................................................ 9
What is Tritium? ..................................................................... 9
Tritium analysis results
Status of tritium analysis ...................................................... 10Reference: Tritium analysis method .................................... 11Column .............................................................................. 13

2

Structure of the monitoring inspection
for radioactive cesium in food
What does the maximum levels

mean?

The Japanese maximum levels (JMLs) for radioactive cesium in general food is set at 100
becquerels (Bq)/kg with the aim of keeping the additional exposure from food after the nuclear
power station accident below the level where the lifetime effects are sufficiently small to pose noproblem (1 millisievert per year). The JMLs are lowered from the maximum value (120 Bq/kg), which
was calculated by taking into account the differences in intake items and amounts according toage and gender, and are designed for all generations, including infants.
As the result of measures preventing the distribution of food products containing radioactive
cesium concentrations above these levels, a survey conducted by the Ministry of Health, Labourand Welfare and the Fukushima Prefectural Government found that the amount of exposure fromfood due to radioactive cesium originating from the nuclear power plant accident is less than
one-hundredth of one millisievert per year, which is the intended level.
Source :The Story of Food and Radioactive Materials (Ministry of Health, Labour and Welfare and others)
Response to Radionuclides in Food (Ministry of Health, Labour and Welfare) (https://www.mhlw.go.jp/shinsai_jouhou/shokuhin-detailed.html#kijun)
Results of Radiation Monitoring of Daily Foods (Fukushima Prefectural Government) (http://www.pref.fukushima.lg.jp/site/portal/nichijoshoku-moni.html)

Framework of the monitoring
Monitoring plan is developed mainly by local governmentsMonitoring areas

Discussion onleft items anddevelopmentof plans.

Target species
Frequency

Implementationof themonitoring

Safety isconfirmed by themonitoring

Shipping

To thediningtable

Shipping
S

If the radioactivity level ofthe product exceeds JMLs?
3

100 Bq/kg
or less

Result exceeded
the Japanesemaximum level(100 Bq/kg)

Request for suspension of shipment
by national or local government
・If the radioactive cesium concentration is higher thanJMLs in particular produce at a single location, therelevant local government requests the producer tosuspend the shipment.
・If the radioactive cesium concentration is higher
than JMLs at multiple locations, the national
government designates/instructs the produce andthe area from where the shipment is suspended.

The lot of the product is recalled and disposed of and further
shipments are suspended, thereby not distributed at themarket.

Process of thelaboratory test

Fishery products sent from local ports
are received, and checked for catch
location and species.

Amount of detected radiation

1 Receipt of fishery productsThis is how theradioactive cesiums aredetected.

An example of ameasurement result10610310500

1000

1500

Energy (keV)of body
2 Measurement
length and weight

5 Analysis

3 Preparation of mince

into an
4 Placeanalytical beaker

Edible parts of the fish (mainlymuscle) are thoroughly minced
for the test.

The concentration of radioactive
cesium per kilogram (Bq/kg) forthe edible portion is obtained as
the result of the measurement.

Fishery products are properlytested.

4Concentration of radioactive cesiumin marine fish species
Results of the analysis of radioactive cesium inmarine fish species
After the nuclear power station accident, the number of samples exceeding the JMLs has
decreased over time. In Fukushima Prefecture, there have been only four samples exceeding
JMLs since FY (Japanese fiscal year, 1 April to 31 March) 2015, and in prefectures other than
Fukushima, no sample has exceeded JMLs since September 2014.
(As of January 31, 2023)

Fukushima
prefecture(Samples)
exceeding 100 Bq/kg

Total number of samples: 74,742
Number of samples over 100 Bq/kg: 2,101(Samples) equal to andbelow 100 Bq/kg

Number of samples equal to and below
100 Bq/kg: 72,641

Exceeded rate(Samples)48

10,00035%8,000

40

1

13%

0

8,842

8,705
1,077

50

0791

6,000
4,000

00181

（%）

8,633

7,666

30

18,559

2

5,456
2%

2,000

0

6,229

1,997 5,479

3,975

20

3,984
3,116

10

0.5%

0%

0%

0%

0.02%

0% 0.03%

0.05%

0%

2014

2015

2016

2017

2018

2019

2020

2021

2022 (FY)

00
2011

2012

2013

Other
prefectures

Total number of samples: 84,361
Number of samples over 100 Bq/kg: 177
Number of samples equal to and below 100 Bq/kg: 84,184(Samples)（%）

50

12,00051
10,000

9,866

8,000
6,000

12

2

09,5288,992

112

0

7,745

7,086

4,000

0
6,317

4,249
2,000

3%

0.5%

40

000030020

5,579

0.1% 0.02%

0%

0%

0%0%

2013

2015

2016

2017

2018

5,245
0%

7,978
6,414

5,185

100%

0%

0%

2020

2021

2022 (FY)

0
2011

5

2012

2014

2019

0

Changes in radioactive cesium concentration inmarine fish species
After the accident, concentrations of radioactive cesium in specimens have promptly
decreased with the passage of time. Today, although radioactive cesium concentrations doexceed the JMLs on extremely rare occasions, virtually all measurements fall below thedetection limit.

15,00014,000134Cs+137Cs (Bq/kg)

13,00012,000
5,000
4,000
3,000
2,000

100Bq/kg

1,000

Below thedetection limit (*)

2011 2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

20222023
(CY)

1,400

134Cs+137Cs (Bq/kg)

1,300
500
400
300
200
100
Below thedetection limit (*)

2015

2016

2017

2018

2019

2020

2021

2022 2023(CY)*Detailed information about BDL (below detection limit) is provided in the column on the last page.

6Concentration of radioactive cesiumin freshwater fish species
Radioactive cesium in freshwater fish species
The number of samples exceeding JMLs is decreasing with the passage of time.

(As of January 31, 2023)

Fukushima
prefecture(Samples)
exceeding 100 Bq/kg(Samples)below 100 Bq/kg

Total number of samples: 8,589
Number of samples over 100 Bq/kg: 375
Number of samples equal to and below
100 Bq/kg: 8,214(Samples)Exceeded rate
（%）

450

1,200

27

1,000

32%

57

88

800

7173
600

13%

400
200
0372

567

626

584628
3%

1%

30

1,179

911

8%

400697

2904

742

426

0.6%

020384107781%0.6%

0.3%

0%

0.5%

0%
02011

2012

2013

Otherprefectures

2014

2015

2016

2017

2018

2019

2020

2021

2022 (FY)The number of samples
exceeding the limit is gradually
decreasing.

Total number of samples: 18,143
Number of samples over 100 Bq/kg: 372
Number of samples equal to and below
100 Bq/kg: 17,771（%）(Samples)

163

3,000

23

2,500
2,000
1,500
1,000

2,560

114

7

1,781

1,530

6%

482

7

7
2,2142%

2011

40

2,573

19%

500
05052

2012

2013

1%
2014

30

3
1,300

0
1,204

2
1,004

1
1,044

0
1,083

0996

20
100.4%0.5%

0.2%

0%

0.2%

0.1%

0%

0%

2015

2016

2017

2018

2019

2020

2021

2022 (FY)0Changes in radioactive cesium concentration in
major freshwater fish species
Cesium is very similar to potassium, a kind of salt that is essential for life. Due to the lower
concentrations of salts in water environment, compared to marine species, freshwater
species tend to keep salts (such as sodium and potassium) once taken into their bodies, so
the cesium is also hardly expeled from the body.
Since cultured IWANA (char) and YAMAME (land-locked cherry salmon) are raised on acontrolled diet with adequate salts, no case has exceeded the JML.
IWANA (wild)
YAMAME (wild)

Example of freshwater fish species (wild IWANA and YAMAME)
19,000400

18,000134Cs+137Cs (Bq/kg)

300
200

3,000

100
Below thedetection limit (*)

2,000

2019 2020 2021

2022 2023(CY)

100Bq/kg

1,000

Below thedetection limit (*)

2018

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

20222023(CY)

Example of freshwater fish species (cultured IWANA and YAMAME)
IWANA (cultured)
YAMAME (cultured)

134Cs+137Cs (Bq/kg)

400300200

100

Below thedetection limit (*)

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

2021

20222023(CY)*Detailed information about BDL (below detection limit) is provided in the column on the last page.

8ALPS Treated Water and Tritium Testing
What is ALPS Treated Water?
ALPS treated water refers to water purified by multi-nuclide removal equipment (ALPS:Advanced Liquid Processing System), etc. for nuclides other than tritium until it meetsthe regulatory standards specified by the state for release to the environment.
ALPS treated water is released after diluting the tritium concentration with seawater toless than 1,500 Bq/L. This is about one-seventh of the World Health Organization's(WHO) drinking water quality guidelines.

What is Tritium?
Tritium (³H) is a type of hydrogen. In addition to being naturally generated whenhydrogen is struck by cosmic rays, it is also generated by nuclear power plant
operations and nuclear tests. Tritium emits beta radiation, and within 12.3 years, half ofthe tritium turns into helium-3, which emits no radiation.
Tritium is commonly found in seawater, fresh water, rainwater, and tap water as tritium
water combined with oxygen, and there are always dozens of becquerels of tritium in ourbody.
The beta radiation emitted by the tritium is so weak that it cannot pass through a single
piece of paper. Therefore, the degree of impact on the human body (effective dosecoefficient) is about 1/700 of cesium-137. In addition, the effects of tritium are notincluded in the regulatory scope of food standards, as it is not considered necessary toconsider them in food.
Also, tritium ingested in humans and fish and shellfish behaves almost the same aswater and is excreted relatively quickly outside the body, so unlike radioactive cesium, it
does not accumulate in the body and is not concentrated.

ElectronElectron

ProtonProtonHydrogen(¹H)

Neutron NeutronTritium

Hydrogen³H

H
OxygenOTritium(³H)

Difference between hydrogen andtritium atoms (schematic)

Tritium water molecule (schematic)

Fisheries Agency website Effects of Radioactive Substances on Fishery Products and Responses About Tritium
https://www.jfa.maff.go.jp/j/koho/saigai/index.html

9Tritium analysis results
Status of tritium analysis
Inspections of tritium are carried out for seafood landed from Hokkaido to Chiba, mainly
in Fukushima Prefecture. In fiscal 2022, 86 samples were tested in Fukushima
Prefecture and 130 samples were tested outside Fukushima Prefecture for a total of 216
samples (46 species including shellfish, seaweed, etc.). All results were below thedetection limit.
Tritium concentration in seafood (analysis results)（Bq/kg）

10,000World Health Organization (WHO) drinking
water quality guidelines: 10,000 (Bq/L)

1,000

100

10Detection limit value
10.1
Jul 1, 2022 Aug 1, 2022 Sep 1, 2022 Oct 1, 2022 Nov 1, 2022 Dec 1, 2022 Jan 1, 2023 Feb 1, 2023

(Collection date)

Tritium concentration in seawater（Bq/L）

10,0001,000100

Measured value
1010.1
May 1, 2021

Jul 1, 2021

Sep 1, 2021

Nov 1, 2021

Jan 1, 2021

Mar 1, 2021

(Collection date)

The graph of tritium concentration in seawater was prepared by the Fisheries Agency based on the Environmental Radiation Database.
Environmental Radiation Database
https://www.kankyo-hoshano.go.jp/data/database/10

Reference

Tritium analysis method

Tritium testing is performed using the tritium water contained in the sample, so caremust be taken to ensure that the sample does not come into contact with other waterthat may affect the test results. Unlike cesium analysis, tritium analysis takes time. It
usually takes about one to two months for the results of the analysis to be available after
the seafood has been transported to the analysis facility.

Collected moisture3

Dissolve the collectedmoisture from the ice.

1
Preparation of mince
Make the finely minced edible
part into a thin plate andfreeze it.

2Extraction of water
Extract moisture from thefrozen mince using avacuum freeze dryer.

11

4Refinement ofcollected water
Decompose the oil andprotein contained in thecollected water and refine
the sample into cleanwater.

6Analysis
Measure the sample
using a liquid scintillation
counter.

5
Mixing with reagent andsettling
Mix the purified water with areagent and leave to settle ina cool dark location.
12

Cooperation with the International
Atomic Energy Agency (IAEA)

ColumnThe IAEA and Japanese laboratories measured radionuclides using the same specimens
extracted from fishery products, and the results confirmed that the measurement method of
the Japanese laboratories is appropriate and has a high level of accuracy and competency.

Change in radioactive cesium
concentration in marine fishery products
before the nuclear power plant accident

ColumnThe concentration of radioactive cesium (137Cs) in marine fishery products such as fish andoctopus had remained below 1Bq/kg from 1983 to 2010. Radioactive cesium was present in
the environment previously due to the effect of atmospheric nuclear tests conducted mainlyin the northern hemisphere.

Chronological change of radioactive cesium (137Cs)
in marine fishery productsRadioactive cesium
was present in small amounts
before the nuclear power
station accident.

Cesium-137
21009

2008

2007

2006

2005

2004

2003

2002

2001

2000

2099

2098

1997

1996

1995

1994

1993

1992

1991

1990

1989

1988

1987

1986

1985

1984

19

19

Detection
limit

83

119

Concentration

Bq/kg (fresh fishery products)
3

Year of sampling

The graph above indicates the radioactive cesium levels measured in the waters around nuclear power stations in Japan.
For details, please refer to “Protection of Fishing Grounds” (in Japanese) on the website of the Marine Ecology ResearchInstitute. (URL: https://www.kaiseiken.or.jp/publish/itaku/itakuseika.html)

13

Column

What is the detection limit?

● The detection limit means the lowest concentration of target substance thatan analytical device can detect.
Differences in detection limits occur when performing analyses even using the same device if theweight of the sample placed into the beaker and/or the duration of the measurement are different. The
monitoring of radionuclides in food is implemented in accordance with the official testing method,“Testing Methods for Radioactive Substances in Food” and “Application of testing methods forradioactive substances in food” provided by the Ministry of Health, Labour and Welfare. The detection
limit is set well below the Japanese maximum levels in food, generally at around 20-30 Bq/kg.

No.

Fish species

PrefectureRadioactive cesium (137Cs) [unit: Bq/kg]

9617

Chub mackerel

MiyagiBelow the detection limit（＜0.571）

9618

Chub mackerel

MiyagiBelow the detection limit（＜2.98）

9619

Hilgendorf saucord

MiyagiBelow the detection limit（＜3.59）

9620

Japanese sardine

MiyagiBelow the detection limit（＜4.34）(Source) the website of the Fisheries Agency

Table: Example of the result of the monitoring ofradionuclides in fishery products.

This value isthe detectionlimit.

The detection limit
drops when the weight of themeasured sample increases.

14

Results of the monitoring of radionuclides in fishery products are available on thewebsite of the Fisheries Agency. Pamphlets discussing various questions
concerning radionuclides in fish from a scientific perspective are also available on
the website of the Japan Fisheries Research and Education Agency.

Website of the Fisheries Agency (in English):https://www.jfa.maff.go.jp/j/housyanou/kekka.html
Website of the Japan Fisheries Research and Education Agency:
FAQ for Radioactivity and Fish (in Japanese)
http://www.fra.affrc.go.jp/bulletin/radioactivity_pamphlet2018/cover_index.html

We can get
more detailed informationfrom the websites
and pamphlets.

Fisheries Agency Radioactive Materials

SearchResearch and Technological Guidance Division,
Resources Enhancement Promotion Department, Fisheries Agency of Japan
1-2-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8907

TEL: 03-6744-2030

Central Laboratory, Marine Ecology Research Institute
300 Iwawada, Onjuku-machi, Isumi-gun, Chiba 299-5105

TEL: 0470-68-5111