Summary for understanding
12
Transcript of Summary for understanding
March 2020
Fisheries Agency of Japan
For �
sh co
nsumption with peace of mind
Summary forunderstanding
the monitoring inspectionof radioactive materials
Website of the Fisheries Agency (in English): https://www.jfa.maff.go.jp/e/inspection/index.html
Research and Technological Guidance Division,Resources Enhancement Promotion Department, Fisheries Agency of Japan1-2-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8907 TEL: 03-6744-2030
Central Laboratory, Marine Ecology Research Institute300 Iwawada, Onjuku-machi, Isumi-gun, Chiba 299-5105 TEL: 0470-68-5111
This pamphlet is prepared as part of the promotion project for the monitoring survey of the effect of radioactive materials in FY2019.
Results of the inspection of radioactive materials in �shery products are available on the website of the Fisheries Agency. Pamphlets discussing various questions concerning radioactive materials in �sh from a scienti�c perspective are also available on the website of the Japan Fisheries Research and Education Agency.
We can get
more detailed information
from the websites
and pamphlets.
Fisheries Agency Radioactive Materials Search
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
Let's learn about �sheriesin Fukushima!Preface
The accident at the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Station in March 2011 resulted in the leakage of radioactive materials and led to concerns over the contamination of �shery products.
To ensure food safety, the standard limits for radioactive materials in food are established and relevant prefectures conduct the monitoring inspections based on the guideline, "Concepts of Inspection Planning and the Establishment and Cancellation of Items and Areas to which Restriction on Distribution and/or Consumption of Foods concerned Applies" (revised on March 23, 2020) developed by the Nuclear Emergency Response Headquarters (whose director-general is the Prime Minister).
The Fisheries Agency is systematically conducting monitoring surveys for radioactive materials for marine and freshwater �shery products in East Japan to ensure the safety of �shery products and to promptly provide correct information concerning radioactive materials in such products.
Preface/Table of Contents .............................................................. 1
Let's learn about �sheries in Fukushima........................................ 2
Structure of the monitoring inspection for radioactive materials in food .... 3
Framework of the monitoring inspections...................................... 3
Process of the actual inspection ................................................... 4
Finding from the results of the monitoring inspections
Concentration of radioactive cesium in marine �sh species
Results of the analysis of radioactive cesium in marine �sh species ......... 5
Excess ratio for the standard limit (marine �sh species).......................... 6
Changes in radioactive cesium concentration in major marine �sh species ... 6
Concentration of radioactive cesium in freshwater �sh species
Results of the analysis of radioactive cesium in freshwater �sh species.... 7
Excess ratio for the standard limit (freshwater �sh species) .................... 8
Changes in radioactive cesium concentration in major freshwater �sh species ... 8
Column............................................................................................. 9
Table ofContents
Trial �shing operations and sales of catches with a lower radioactive level have been conducted since June 2012 to examine evaluations at shipped markets and gain basic information needed to resume �shery operations in Fukushima prefecture.
Meetings are held to
discuss which �sh species
are to be captured.
Fishermen catch
�sh determined in
the meeting.
All �sh are to be
shipped only after their
safety is con�rmed.
Fish ensured to
be safe are sold
in the market.
Samples extracted from the
catch are tested for radioactive
materials to ensure safety.
Target species of the trial �shing operation: All marine �sh speciesNote 1: The �sheries products for shipping are limited to those that are below 50
Bq/kg for radioactive cesium level (the voluntary limit of Fukushima Prefectural Federation of Fisheries Co-operative Associations) (cf. the standard limit of the Japanese government: 100 Bq/kg)
Note 2: As of March 1, 2020, there are no �sh species subject to restrictions on distribution issued by the Director-General of the Nuclear Emergency Response Headquarters
Landing Olive �ounder landed Fish auction
Shipped �sh are con�rmed to be safe.
To the dining table
It has been nine years since the accident, and safety
has been con�rmed in all marine �sh species.
1 2
Let's learn about �sheriesin Fukushima!Preface
The accident at the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Station in March 2011 resulted in the leakage of radioactive materials and led to concerns over the contamination of �shery products.
To ensure food safety, the standard limits for radioactive materials in food are established and relevant prefectures conduct the monitoring inspections based on the guideline, "Concepts of Inspection Planning and the Establishment and Cancellation of Items and Areas to which Restriction on Distribution and/or Consumption of Foods concerned Applies" (revised on March 23, 2020) developed by the Nuclear Emergency Response Headquarters (whose director-general is the Prime Minister).
The Fisheries Agency is systematically conducting monitoring surveys for radioactive materials for marine and freshwater �shery products in East Japan to ensure the safety of �shery products and to promptly provide correct information concerning radioactive materials in such products.
Preface/Table of Contents .............................................................. 1
Let's learn about �sheries in Fukushima........................................ 2
Structure of the monitoring inspection for radioactive materials in food .... 3
Framework of the monitoring inspections...................................... 3
Process of the actual inspection ................................................... 4
Finding from the results of the monitoring inspections
Concentration of radioactive cesium in marine �sh species
Results of the analysis of radioactive cesium in marine �sh species ......... 5
Excess ratio for the standard limit (marine �sh species).......................... 6
Changes in radioactive cesium concentration in major marine �sh species ... 6
Concentration of radioactive cesium in freshwater �sh species
Results of the analysis of radioactive cesium in freshwater �sh species.... 7
Excess ratio for the standard limit (freshwater �sh species) .................... 8
Changes in radioactive cesium concentration in major freshwater �sh species ... 8
Column............................................................................................. 9
Table ofContents
Trial �shing operations and sales of catches with a lower radioactive level have been conducted since June 2012 to examine evaluations at shipped markets and gain basic information needed to resume �shery operations in Fukushima prefecture.
Meetings are held to
discuss which �sh species
are to be captured.
Fishermen catch
�sh determined in
the meeting.
All �sh are to be
shipped only after their
safety is con�rmed.
Fish ensured to
be safe are sold
in the market.
Samples extracted from the
catch are tested for radioactive
materials to ensure safety.
Target species of the trial �shing operation: All marine �sh speciesNote 1: The �sheries products for shipping are limited to those that are below 50
Bq/kg for radioactive cesium level (the voluntary limit of Fukushima Prefectural Federation of Fisheries Co-operative Associations) (cf. the standard limit of the Japanese government: 100 Bq/kg)
Note 2: As of March 1, 2020, there are no �sh species subject to restrictions on distribution issued by the Director-General of the Nuclear Emergency Response Headquarters
Landing Olive �ounder landed Fish auction
Shipped �sh are con�rmed to be safe.
To the dining table
It has been nine years since the accident, and safety
has been con�rmed in all marine �sh species.
1 2
1
2
3
100 Bq/kgor less
Structure of the monitoring inspectionfor radioactive materials in food
Process of the actualinspection
What does the standard limit mean?What does the standard limit mean?
In Japan, the standard limit for radioactive materials in general foods is set at 100 Bq/kg. This is lower than the strictest value (120 Bq/kg) of all thresholds for all age groups, which are set by taking into account differences in preferences and amount of food consumption among different age groups and sexes. The level of the standard limit ensures that the lifetime effect of radioactive materials in food is suf�ciently low as to be safe even when a person continues to eat the food (1 milli-sievert or less per year). This standard limit is safe for all age groups including infants.
Source: Compiled based on The Story of Food and Radioactive Materials (Ministry of Health, Labour and Welfare and others)
Monitoring areas
Target species
Frequency
Monitoring plan is developed mainly by local governments
Framework of the monitoring inspections
Shipping
・If the radioactive cesium level is higher than the standard limit at a single location, the relevant local government requests producers to suspend shipping voluntarily.
・If the radioactive cesium level is higher than the standard limit at multiple locations, the national government instructs restriction on distribution.
Request for voluntary suspension orinstruction of restriction on distribution
If the radioactivity level exceeds the standard limit?A voluntary suspension or restriction on distribution will be implemented regarding distribution of the relevant �sh species.
Fishery products exceeding the standard limit would not be distributed to the market.
Measurement of body length and weight
Place into an analytical beaker
AnalysisThe concentration of radioactive materials per kilogram (Bq/kg) for the edible portion is obtained as the result of the measurement.
Preparation of minceEdible parts of the �sh (mainly muscle) are thoroughly minced for the test.
Safety iscon�rmed by
the inspections.
ShippingTo thediningtable
This is howthe radioactive materials
is detected.
106
103
10 500 1000 1500
Energy (keV)
Receipt of �shery productsFishery products sent from local ports are received, and checked for catch location and species.
4
5
An example of ameasurement result
Discussion on left items and development of plans.
Implemen-tation of
the monitoring
survey
Am
ount
of d
etec
ted
rad
iatio
n
Fishery products are
inspected following
the appropriate process.
Result exceeded the standard limit
(100 Bq/kg)
3 4
1
2
3
100 Bq/kgor less
Structure of the monitoring inspectionfor radioactive materials in food
Process of the actualinspection
What does the standard limit mean?What does the standard limit mean?
In Japan, the standard limit for radioactive materials in general foods is set at 100 Bq/kg. This is lower than the strictest value (120 Bq/kg) of all thresholds for all age groups, which are set by taking into account differences in preferences and amount of food consumption among different age groups and sexes. The level of the standard limit ensures that the lifetime effect of radioactive materials in food is suf�ciently low as to be safe even when a person continues to eat the food (1 milli-sievert or less per year). This standard limit is safe for all age groups including infants.
Source: Compiled based on The Story of Food and Radioactive Materials (Ministry of Health, Labour and Welfare and others)
Monitoring areas
Target species
Frequency
Monitoring plan is developed mainly by local governments
Framework of the monitoring inspections
Shipping
・If the radioactive cesium level is higher than the standard limit at a single location, the relevant local government requests producers to suspend shipping voluntarily.
・If the radioactive cesium level is higher than the standard limit at multiple locations, the national government instructs restriction on distribution.
Request for voluntary suspension orinstruction of restriction on distribution
If the radioactivity level exceeds the standard limit?A voluntary suspension or restriction on distribution will be implemented regarding distribution of the relevant �sh species.
Fishery products exceeding the standard limit would not be distributed to the market.
Measurement of body length and weight
Place into an analytical beaker
AnalysisThe concentration of radioactive materials per kilogram (Bq/kg) for the edible portion is obtained as the result of the measurement.
Preparation of minceEdible parts of the �sh (mainly muscle) are thoroughly minced for the test.
Safety iscon�rmed by
the inspections.
ShippingTo thediningtable
This is howthe radioactive materials
is detected.
106
103
10 500 1000 1500
Energy (keV)
Receipt of �shery productsFishery products sent from local ports are received, and checked for catch location and species.
4
5
An example of ameasurement result
Discussion on left items and development of plans.
Implemen-tation of
the monitoring
survey
Am
ount
of d
etec
ted
rad
iatio
n
Fishery products are
inspected following
the appropriate process.
Result exceeded the standard limit
(100 Bq/kg)
3 4
Concentration of radioactive cesiumin marine �sh species Excess ratio for the standard limit
Results of the analysis of radioactive cesium in marine �sh speciesImmediately after the nuclear power station accident, about 30% of samples in Fukushima prefecture exceeded the current standard limit (100 Bq/kg). Since then, the number of samples exceeding the standard limit tends to decrease with the passage of time. In Fukushima prefecture, no sample has exceeded the standard limit since February 2019, and in prefectures other than Fukushima, no sample has exceeded the standard limit since September 2014.
Changes in radioactive cesium concentration in major marine �sh speciesSome samples of surface-layer �sh (e.g. juvenile Japanese sandlance and whitebait) and demersal �sh (e.g. olive founder) exceeded the current standard limit (100 Bq/kg) immediately after the nuclear power station accident, but the number of such samples and the concentration of radioactive cesium detected has promptly decreased with the passage of time. Currently, radioactive cesium levels are signi�cantly below the standard limit for samples.
Marine �sh species
10
100
1,000
10,000
100,000
134 C
s+13
7 Cs
(Bq/
kg)
250
200
150
100
50
134 C
s+13
7 Cs
(Bq/
kg)
2017 2018
10
100
1,000
10,000
100,000
2019
Surface-layer �sh(juvenile Japanese sandlance and whitebait) Demersal �sh (olive founder)
Below the detection limit
← Detailed information is available in the column on the last page.
Below thedetection limit
Below thedetection limit
Other prefectures
Fukushima prefecture exceeding 100 Bq/kg
below 100 Bq/kg
(FY)(FY)
Olive �ounderJuvenile Japanese sandlance
Whitebait
As of January 31, 2020
2011
2012
2013
2014
2015
2016
2018
2019
2017
2011
2012
2013
2014
2015
2016
2017
2018
2019
Below thedetection limit
10,000
(Samples)
8,000
6,000
4,000
2,000
020182011 2012 2013 2014 2015 2016
1,077
791
18148 0 0
1
1,997
5,4797,666
8,705 8,633 8,842
6,229
0
4,676
2017
0
8,559
2011 2012 2013 2014 2015 2016
10,000
(Samples)
8,000
6,000
4,000
2,000
02017
112
51 122
00
0
4,249
9,866 9,528 8,9927,745 7,086 6,317
0
4,417
2018
0
5,579
2019(FY)
2019(FY)
0
5
10
15
20
25
30
20182017201620152014201320122011
(%)
Exce
ss ra
tio fo
r the
lim
it (1
00 B
q/kg
)
0%0% 0% 0.01% 0%
2019(FY)
Total number of samples: 126,840
Number of samples exceeding 100 Bq/kg: 2,275
Number of samples below 100 Bq/kg: 124,565
Since FY2015, only one sample (detected in FY2018) has exceeded the standard limit.
(As of January 31, 2020)
5 6
Concentration of radioactive cesiumin marine �sh species Excess ratio for the standard limit
Results of the analysis of radioactive cesium in marine �sh speciesImmediately after the nuclear power station accident, about 30% of samples in Fukushima prefecture exceeded the current standard limit (100 Bq/kg). Since then, the number of samples exceeding the standard limit tends to decrease with the passage of time. In Fukushima prefecture, no sample has exceeded the standard limit since February 2019, and in prefectures other than Fukushima, no sample has exceeded the standard limit since September 2014.
Changes in radioactive cesium concentration in major marine �sh speciesSome samples of surface-layer �sh (e.g. juvenile Japanese sandlance and whitebait) and demersal �sh (e.g. olive founder) exceeded the current standard limit (100 Bq/kg) immediately after the nuclear power station accident, but the number of such samples and the concentration of radioactive cesium detected has promptly decreased with the passage of time. Currently, radioactive cesium levels are signi�cantly below the standard limit for samples.
Marine �sh species
10
100
1,000
10,000
100,000
134 C
s+13
7 Cs
(Bq/
kg)
250
200
150
100
50
134 C
s+13
7 Cs
(Bq/
kg)
2017 2018
10
100
1,000
10,000
100,000
2019
Surface-layer �sh(juvenile Japanese sandlance and whitebait) Demersal �sh (olive founder)
Below the detection limit
← Detailed information is available in the column on the last page.
Below thedetection limit
Below thedetection limit
Other prefectures
Fukushima prefecture exceeding 100 Bq/kg
below 100 Bq/kg
(FY)(FY)
Olive �ounderJuvenile Japanese sandlance
Whitebait
As of January 31, 2020
2011
2012
2013
2014
2015
2016
2018
2019
2017
2011
2012
2013
2014
2015
2016
2017
2018
2019
Below thedetection limit
10,000
(Samples)
8,000
6,000
4,000
2,000
020182011 2012 2013 2014 2015 2016
1,077
791
18148 0 0
1
1,997
5,4797,666
8,705 8,633 8,842
6,229
0
4,676
2017
0
8,559
2011 2012 2013 2014 2015 2016
10,000
(Samples)
8,000
6,000
4,000
2,000
02017
112
51 122
00
0
4,249
9,866 9,528 8,9927,745 7,086 6,317
0
4,417
2018
0
5,579
2019(FY)
2019(FY)
0
5
10
15
20
25
30
20182017201620152014201320122011
(%)
Exce
ss ra
tio fo
r the
lim
it (1
00 B
q/kg
)
0%0% 0% 0.01% 0%
2019(FY)
Total number of samples: 126,840
Number of samples exceeding 100 Bq/kg: 2,275
Number of samples below 100 Bq/kg: 124,565
Since FY2015, only one sample (detected in FY2018) has exceeded the standard limit.
(As of January 31, 2020)
5 6
Concentration of radioactive cesiumin freshwater �sh species Excess ratio for the standard limit
Results of the analysis of radioactive cesium in freshwater �sh speciesImmediately after the nuclear power station accident, many freshwater �sh species exceeded the current standard limit (100 Bq/kg). Since then, the number of samples exceeding the standard limit tends to decrease with the passage of time.
Changes in radioactive cesium concentration in major freshwater �sh speciesThe number of samples of wild IWANA (char) and YAMAME (land-locked cherry salmon) exceeding the standard limit is substantially decreased compared to immediately after the accident. At the same time, no samples of cultured IWANA and YAMAME have exceeded the standard limit.
Example of freshwater �sh species(cultured IWANA and YAMAME)
Example of freshwater �sh species(wild IWANA and YAMAME)
134 C
s+13
7 Cs
(Bq/
kg)
10
100
(FY)
Below the detection limit
Other prefectures
Fukushima prefecture
←Detailed information is available in the column on the last page.
exceeding 100 Bq/kg
below 100 Bq/kg
Freshwater �sh species
IWANA (wild)YAMAME (wild)
IWANA (cultured)YAMAME (cultured)
The number of samples
exceeding the limit is
gradually decreasing.
As of January 31, 2020
2011
2012
2013
2014
2015
2016
2017
2018
2019
2011
2012
2013
2014
2015
2016
2017
2018
2019
134 C
s+13
7 Cs
(Bq/
kg)
100,000
10
100
1,000
10,000
2017 2018 2019
100
400
500
300
200
(FY)
Below thedetection limit
Below thedetection limit
Below thedetection limit
2011 2012 2013 2014 2015 2016 2017
1,200
(Samples)
800
600
400
200
1,000
0
17388
27
74 8
372
567
911
628697
742
4
1,107
2018
5
904
57
626
20182011 2012 2013 2014 2015 2016 2017
3,000
2,500
2,000
1,500
1,000
500
0
114
163 52
23
7
73
482
2,560 2,573
2,2141,781
1,5301,300
2
817
0
1,204
2019(FY)
2019(FY)
(Samples)
0
5
10
15
20
25
30
20182017201620152014201320122011
0.6% 0.5% 0.5% 0.2% 0.3%
(%)
2019(FY)
Exce
ss ra
tio fo
r the
lim
it (1
00 B
q/kg
)
Total number of samples: 21,759
Number of samples exceeding 100 Bq/kg: 744
Number of samples below 100 Bq/kg: 21,015
Some �sh species exceed the standard limit. However, the frequency of such samples and the concentration of radioactive cesium detected tend to decrease year by year.
As of January 31, 2020
7 8
Concentration of radioactive cesiumin freshwater �sh species Excess ratio for the standard limit
Results of the analysis of radioactive cesium in freshwater �sh speciesImmediately after the nuclear power station accident, many freshwater �sh species exceeded the current standard limit (100 Bq/kg). Since then, the number of samples exceeding the standard limit tends to decrease with the passage of time.
Changes in radioactive cesium concentration in major freshwater �sh speciesThe number of samples of wild IWANA (char) and YAMAME (land-locked cherry salmon) exceeding the standard limit is substantially decreased compared to immediately after the accident. At the same time, no samples of cultured IWANA and YAMAME have exceeded the standard limit.
Example of freshwater �sh species(cultured IWANA and YAMAME)
Example of freshwater �sh species(wild IWANA and YAMAME)
134 C
s+13
7 Cs
(Bq/
kg)
10
100
(FY)
Below the detection limit
Other prefectures
Fukushima prefecture
←Detailed information is available in the column on the last page.
exceeding 100 Bq/kg
below 100 Bq/kg
Freshwater �sh species
IWANA (wild)YAMAME (wild)
IWANA (cultured)YAMAME (cultured)
The number of samples
exceeding the limit is
gradually decreasing.
As of January 31, 2020
2011
2012
2013
2014
2015
2016
2017
2018
2019
2011
2012
2013
2014
2015
2016
2017
2018
2019
134 C
s+13
7 Cs
(Bq/
kg)
100,000
10
100
1,000
10,000
2017 2018 2019
100
400
500
300
200
(FY)
Below thedetection limit
Below thedetection limit
Below thedetection limit
2011 2012 2013 2014 2015 2016 2017
1,200
(Samples)
800
600
400
200
1,000
0
17388
27
74 8
372
567
911
628697
742
4
1,107
2018
5
904
57
626
20182011 2012 2013 2014 2015 2016 2017
3,000
2,500
2,000
1,500
1,000
500
0
114
163 52
23
7
73
482
2,560 2,573
2,2141,781
1,5301,300
2
817
0
1,204
2019(FY)
2019(FY)
(Samples)
0
5
10
15
20
25
30
20182017201620152014201320122011
0.6% 0.5% 0.5% 0.2% 0.3%
(%)
2019(FY)
Exce
ss ra
tio fo
r the
lim
it (1
00 B
q/kg
)
Total number of samples: 21,759
Number of samples exceeding 100 Bq/kg: 744
Number of samples below 100 Bq/kg: 21,015
Some �sh species exceed the standard limit. However, the frequency of such samples and the concentration of radioactive cesium detected tend to decrease year by year.
As of January 31, 2020
7 8
Cooperation with the International Atomic Energy Agency (IAEA)
Column
The IAEA and Japanese laboratories measured radioactive materials using the same specimens extracted from �shery products and the measurement ability of the Japanese laboratories was examined (i.e. pro�ciency test). As a result, the methodology for radioactive material measurement practiced by Japanese laboratories were con�rmed to be appropriate and have a high level of accuracy and competency.
What is the detection limit?Column
The detection limit means the lowest concentration of target material that an analytical device can detect. The value becomes lower as the sample weight and/or duration of measurement increase, meaning detection and measurement of much lower concentrations becomes possible. On the other hand, this also means the number of samples to be analyzed becomes less. Therefore, a required detection limit is maintained for the speci�c purpose of analysis, and the value of the detection limit is presented to clarify that the outcome of the inspection is suf�ciently reliable.
Source: Compiled based on “Analysis of radioactive materials” (in Japanese) (Ministry of Agriculture, Forestry and Fisheries)
Change in radioactive cesium concentrationin marine �shery products before the nuclearpower plant accident
Column
The concentration of radioactive cesium (137Cs) in marine �shery products such as �sh and octopus had remained below 1 Bq/kg from 1983 to 2010. Radioactive cesium was present in the environment previously due to the effect of atmospheric nuclear explosion tests conducted mainly in the northern hemisphere.
3
2
1
Year of sampling
Bq/kg (fresh �shery products)
Detectionlimit
Con
cent
ratio
n
Cesium-137
Chronological change of radioactive cesium (137Cs)in marine �shery products
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 Research Institute. (URL: https://www.kaiseiken.or.jp/publish/itaku/itakuseika.html)
Why is the detection limit different depending on the sample?Q
ADifferences in detection limits occur when performing analyses even using the same device if the weight of the sample placed into the beaker and/or the duration of the measurement are different. The inspection of radioactive materials in food is implemented in accordance with the of�cial testing method, “Testing Methods for Radioactive Substances in Food” and
“Application of testing methods for radioactive substances in food” provided by the Ministry of Health, Labour and Welfare. The detection limit is set to be well below the standard limit (100 Bq/kg).
No. Radioactive cesium (137Cs) [unit: Bq/kg]
9617
9618
9619
9620
Fish species
Chub mackerel
Chub mackerel
Hilgendorf saucord
Japanese sardine
Prefecture
Miyagi
Miyagi
Miyagi
Miyagi
Below the detection limit (<0.571)
Below the detection limit (<2.98)
Below the detection limit (<3.59)
Below the detection limit (<4.34)
Table: Example of the result of the inspectionof radioactive materials in �shery products
(Source) the website of the Fisheries Agency
1983198419851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007200820092010
The detection limit dropswhen the weight of the
measured sample increases.
Radioactive cesiumwas present in small amounts
before the nuclear powerstation accident.
This value is thedetection limit.
9 10
Cooperation with the International Atomic Energy Agency (IAEA)
Column
The IAEA and Japanese laboratories measured radioactive materials using the same specimens extracted from �shery products and the measurement ability of the Japanese laboratories was examined (i.e. pro�ciency test). As a result, the methodology for radioactive material measurement practiced by Japanese laboratories were con�rmed to be appropriate and have a high level of accuracy and competency.
What is the detection limit?Column
The detection limit means the lowest concentration of target material that an analytical device can detect. The value becomes lower as the sample weight and/or duration of measurement increase, meaning detection and measurement of much lower concentrations becomes possible. On the other hand, this also means the number of samples to be analyzed becomes less. Therefore, a required detection limit is maintained for the speci�c purpose of analysis, and the value of the detection limit is presented to clarify that the outcome of the inspection is suf�ciently reliable.
Source: Compiled based on “Analysis of radioactive materials” (in Japanese) (Ministry of Agriculture, Forestry and Fisheries)
Change in radioactive cesium concentrationin marine �shery products before the nuclearpower plant accident
Column
The concentration of radioactive cesium (137Cs) in marine �shery products such as �sh and octopus had remained below 1 Bq/kg from 1983 to 2010. Radioactive cesium was present in the environment previously due to the effect of atmospheric nuclear explosion tests conducted mainly in the northern hemisphere.
3
2
1
Year of sampling
Bq/kg (fresh �shery products)
Detectionlimit
Con
cent
ratio
n
Cesium-137
Chronological change of radioactive cesium (137Cs)in marine �shery products
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 Research Institute. (URL: https://www.kaiseiken.or.jp/publish/itaku/itakuseika.html)
Why is the detection limit different depending on the sample?Q
ADifferences in detection limits occur when performing analyses even using the same device if the weight of the sample placed into the beaker and/or the duration of the measurement are different. The inspection of radioactive materials in food is implemented in accordance with the of�cial testing method, “Testing Methods for Radioactive Substances in Food” and
“Application of testing methods for radioactive substances in food” provided by the Ministry of Health, Labour and Welfare. The detection limit is set to be well below the standard limit (100 Bq/kg).
No. Radioactive cesium (137Cs) [unit: Bq/kg]
9617
9618
9619
9620
Fish species
Chub mackerel
Chub mackerel
Hilgendorf saucord
Japanese sardine
Prefecture
Miyagi
Miyagi
Miyagi
Miyagi
Below the detection limit (<0.571)
Below the detection limit (<2.98)
Below the detection limit (<3.59)
Below the detection limit (<4.34)
Table: Example of the result of the inspectionof radioactive materials in �shery products
(Source) the website of the Fisheries Agency
1983198419851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007200820092010
The detection limit dropswhen the weight of the
measured sample increases.
Radioactive cesiumwas present in small amounts
before the nuclear powerstation accident.
This value is thedetection limit.
9 10
March 2020
Fisheries Agency of JapanFo
r �sh
consumption with peace of m
ind
Summary forunderstanding
the monitoring inspectionof radioactive materials
Website of the Fisheries Agency (in English): https://www.jfa.maff.go.jp/e/inspection/index.html
Research and Technological Guidance Division,Resources Enhancement Promotion Department, Fisheries Agency of Japan1-2-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8907 TEL: 03-6744-2030
Central Laboratory, Marine Ecology Research Institute300 Iwawada, Onjuku-machi, Isumi-gun, Chiba 299-5105 TEL: 0470-68-5111
This pamphlet is prepared as part of the promotion project for the monitoring survey of the effect of radioactive materials in FY2019.
Results of the inspection of radioactive materials in �shery products are available on the website of the Fisheries Agency. Pamphlets discussing various questions concerning radioactive materials in �sh from a scienti�c perspective are also available on the website of the Japan Fisheries Research and Education Agency.
We can get
more detailed information
from the websites
and pamphlets.
Fisheries Agency Radioactive Materials Search
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
