Sea-Dumped Chemical Weapons:
Japan
GLOBAL GREEN USA,
US AFFILIATE OF GREEN CROSS
INTERNATIONAL
June, 2010
Authored by: Ryo Sato
Executive Summary
This paper primarily assesses the document “The National Survey on Toxic Gas
of the Former Army,” prepared by the Japanese Ministry of the Environment,
relating to sea-dumped chemical weapons, as well as other materials listed in the
Endnotes. The issues examined are the history of chemical weapons in Japan
including production, stockpiles and especially sea-dumping of these weapons.
Global Green USA
ABOUT THE AUTHOR
Ryo Sato is a Research Assistant at Global Green USA's Security and Sustainability Program in
Washington, DC. His research primarily focuses on environmental security and sustainability.
ACKNOWLEDGMENTS
This report would not have been possible without the support of Finn Longinotto, and my
colleagues at Global Green USA. I would also like to thank Geoff Carton from the CALIBRE
Systems, Inc., and all those others in the USA and Japan not named here.
POINT OF CONTACT
Paul F. Walker, Marina Voronova-Abrams and Finn Longinotto
Security and Sustainability Program Global Green USA
1100 15th Street, NW, 11th Floor Washington, DC 20005
Phone: 202.222.0700
Cover Photo Credit: One of the suspected dumpsites in Japan
Official website of Miyajima tourism
http://www.miyajima-wch.jp/index_e.html
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Table of Contents
1. History of Japanese Chemical Weapons ........................................... 3
1.1 Categories of Poison Gas ............................................................... 3
1.2 Production of Chemical Weapons and Reported Stockpiles ..... 4
1.3 Disposal of Chemical Weapons in the Ocean .............................. 5
1.4 Production and Disposal in the Island of Ohkuno ...................... 8
2. Potential Risks from Disposal in the Ocean ................................... 11
2.1 Reported Injuries and Deaths ..................................................... 11
2.2 Chemical Weapons Washing Ashore.......................................... 13
3. Chemical Weapons in the Pacific Ocean ........................................ 13
4. Case Study: Offshore of Choshi Bay ............................................... 14
5. Legal Considerations......................................................................... 16
6. Conclusion .......................................................................................... 16
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1. History of Japanese Chemical Weapons (CWs)
1.1 Categories of Poison Gas
Various kinds of toxic gases, signal barrels, pipes, and balloon bombs were produced in Japan until
the end of World War II (WWII). During that time, chemical weapons were categorized into six
colors including toxic chemicals such as Mustard, Lewisite, Phosgene and Hydrogen cyanide.
Table 1 shows the list of poison gases, made by the former Japanese government. Vomiting agent
in Japan was mixed with Diphenylcyanarsine (DA) and Diphenylchloroarsine (DC). In this paper,
all the chemical agents listed below will be considered as chemical weapons including
chloroacetophenone, which was often used by the Japanese army in China during WWII.
Table 1: The categories of poison gases
Army Naming
Category
Type (Agents)
Yellow No.1 Ko
Yellow No.1 Otsu
Yellow No.1 Hei
Yellow No.2
German type Yperite (Mustard agent)
French type Yperite (Mustard agent)
German type cold Yperite (not frozen)
Lewisite
Blister
Blue
Phosgene
Choking
Brown
Hydrogen cyanide
Blood
Red
Diphenylcyanarsine (DA)
Diphenylchloroarsine (DC)
Green
Chloroacetophenone
Vomiting, „Sneezing‟
inJapppp in Japan
Trichloroarsine
White
Source: Japanese Ministry of the Environment Official Website
http://www.env.go.jp/chemi/report/h15-02/002.pdf
Riot control
Toxic smoke-producing
Lewisite Factory on the island of Ohkuno, Hiroshima Prefecture
Source: http://homepage3.nifty.com/dokugasu/kaihou08/kaihou082.html
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1.2 Production of Chemical Weapons and Reported Stockpiles
Chemical weapons were either dumped by the Japanese Army during and after WWII or by the
Allied Forces mainly under the command of the United States between 1945 and 1948.
At the beginning of the First World War, the Japanese government started investigating and
researching chemical weapons, because of information that several countries, especially in
Europe, were developing chemical weapons. The history of the Japanese chemical weapons
program is summarized here1,2:
1914: The Japanese Army started researching chemical weapons
1919: The Army established a research institute of chemical weapons
1923: The Japanese Navy established a chemical weapons laboratory in Tokyo
1929: The Army started producing chemical weapons on the island of Ohkuno in Hiroshima
1933: The government established The School for Chemical Weapon Training in Chiba
1934: The Navy‟s chemical weapons laboratory raised its status to department level
1937: The government established a factory for chemical weapons in Fukuoka Prefecture
1943: The Navy started producing chemical weapons in Samukawa, Kanagawa Prefecture
Complete records on chemical weapons have not been found. However, the current Japanese
government acknowledges that more than fifteen chemical weapon factories and laboratories
operated inside Japan until 1945.3
At the end of the Second World War, more than 30 chemical weapons stockpiles are reported to
have existed in Japan (Figure 1)4. The red circles indicate the locations of chemical weapon
factories or laboratories.
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1.3 Disposal of Chemical Weapons in the Ocean
Most of the chemical weapons were dumped by either the Japanese Army or the Allied Forces
mainly under the command of the U.S. between 1945 and 1948. In other words, massive amounts of
chemical weapons were dumped in a relatively short period around the end of World War II.
After the Japanese government accepted the unconditional surrender on 15th August, 1945, most of
the unused chemical weapons were incinerated and dumped in the ocean, or directly dumped in the
ocean mainly under the command of the U.S. Army. Some weapons, however, were dumped by the
Japanese Army during and right after the end of WWII. This is because sea-dumping was regarded as
one of the safest methods to dispose of chemical weapons, especially for human health.5
The five major types of chemical weapons produced by the Japanese Army before the Second
World War were Mustard, Lewisite, Hydrogen Cyanide, DA and DC. Table 2 lists some locations
of the major sea-dumped Japanese chemical weapons, not including bullets filled with chemicals,
ordered to be disposed of by several countries.
In Japan, „ton‟ stands for metric ton, or tonne (1tonne = 1,000 kg). Japan has been using metric
tons since before WWII. Although there was some information from the U.S. military, most of
the information was from Japanese documents. Furthermore, almost all of the information from
the U.S. military came through the formal Japanese military army officers involved in the issue
and is therefore also in metric tons or tonnes.
Table 2: Major sea-dumped Japanese chemical weapons, with date, location, type and disposal
by country (Source: The Japanese Ministry of the Environment official website)
Date
August 1946
October 1945 –
May 1946
1945 (Around
the end of WW2)
Location
Sea-dumped but Unspecified
Pacific Ocean, off Tokyo,
originating from Choshi
Narashino and Funabashi
(Land),
Some were dumped in the ocean
(unspecified)
Pacific Ocean, Sagami bay, off
Tokyo
Lake Hamana-ko, Shizuoka
Pref.
Beppu Bay, Oita Pref.
Sea-dumped but unspecified
Chemical Weapon or Agent
3,689 tons of Mustard
450 tons of Mustard
Sea-dumped but unspecified
192,849 kg of Mustard
Unspecified
Pacific Ocean, off Kochi Pref.
August, 1946
Beppu Bay, Oita Pref.
More than 2,700 tons of Mustard
and lewisite
990 tons of Diphenylcyanoarsine
7 tons of Chloroacetonphenone
39,967 kg of Mustard
August 1945
August 17, 18,
1945
October, 1945
November 1946
– May 1947
August 1946
Unspecified amount of Mustard
6 tons of Lewisite
Unspecified amount of hydrogen
cyanide
2 tons of Mustard and Lewisite
16 tons of Mustard
2 tons of Lewisite
90,000 kg of Mustard
10 tons of Chloroacetophenone
By Country
U.S.
U.S. and
Australia
Japan
Japan
Japan
Japan
U.S. and
Australia
U.S. and
Australia
U.S. and
Australia
U.S. and
Australia
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The Japanese government has reported that 44 chemical weapon dumping sites exist inside and
offshore the current Japanese territory. However, the government is concerned that there could
be more dumpsites, up to 138, including 29 in water – the ocean, rivers and lakes – which could
pose health risks, as shown in Figure 2 below.6 The numbers in Figure 2, from 1 to 29, indicate
the locations of these dumpsites, and Table 3 shows whether the chemical weapons were dumped
in the ocean, rivers or lakes. The Red, Purple, Orange, and Green circles in Figure 2 show the
disposal of chemical weapons on land. The Blue circle indicates water-dumped sites, with
varying degrees of accuracy, as indicated in the other circles relating to land-dumped sites.
Figure 2: Reported Chemical Weapons Dump sites
Table 3, which follow, shows dumpsites by location and type of water (ocean, rivers and lakes).
The three circles in the column of “Production or Possession” refer to the chemical weapons
research institute in Yugawara, and stock piles in Otaru and Maizuru, respectively, and they are
all next to the ocean. A circle in the column of “Abandonment” means that the Japanese
government has disclosed the information on dumped CW in these areas.
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Table 3: Dumpsites by Location and Type of Water (ocean, rivers and lakes)
Location, Prefecture
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Lake Kussharo-ko,
Hokkaido
Offshore of Abashiri,
Hokkaido
Otaru, Hokkaido
Mutsu Bay, Aomori
Kuji, Ibaraki
Offshore of Kashima,
Ibaraki
Offshore of Choshi,
Chiba
Offshore of Futsu,
Chiba
Yugawara, Kanagawa
Sagami bay, Kanagawa
Sagami river,
Kanagawa
Lake Hamana-ko,
Shizuoka
Lake Sanaru-ko,
Shizuoka
Maizuru, Kyoto
Himeji, Hyogo
Around the island of
Ohkuno, Hiroshima
Offshore of Miyajima,
Hiroshima
Suou, Yamaguchi
Akiho, Yamaguchi
Offshore of
Komatsushima,
Tokushima
Offshore of Omishima
Higai, Ehime
Offshore of Tosa, Kochi
Kurume, Fukuoka
Kanda, Fukuoka
Misumi, Kumamoto
Minamata, Kumamoto
Around Beppu bay, Oita
Bungosuidou, Oita
Okinawa
Production
or
Possession
O
O
O
Abandon
-ment
Discovery,
Victim,
Minesweeping
Blister
O
O
O
O
O
O
O
O
O
O
O
Vomiting,
Sneezing
Choking,
Blood
Others
Category
O
Lake
O
Ocean
O
Ocean
Ocean
Ocean
Ocean
O
O
O
O
O
O
Ocean
O
O
O
Ocean
O
O
O
O
O
O
O
O
O
O
Lake
O
O
O
Ocean
O
O
O
O
O
O
O
O
O
O
O
Ocean
Ocean
Ocean
O
Ocean
O
Ocean
Ocean
Ocean
O
Ocean
O
O
O
O
O
O
Ocean
River
Ocean
Ocean
Ocean
Ocean
Ocean
Lake
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Ocean
Ocean
River
O
O
O
O
Source: The Japanese Ministry of the Environment official website
http://www.env.go.jp/chemi/report/h15-02/008.pdf
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1.4 Production and Disposal in the Island of
Ohkuno
The island of Ohkuno is located in the south east area of
Hiroshima. It has a coastline of 4.3 km and covers an area
of 71 hectares. Although Ohkuno has been developed as a
National Vacation Village and become a public health
resort today, the island produced poison gases for the
Japanese Army from 1929 to 1945. Chemical weapon
factories were built in the west and south west area of the
island, as indicated by the two red circles in the figure to
the right.
All the chemical weapons used by the Japanese Army, as
opposed to the Japanese Navy, during WWII were
produced on this small island and went all over Japan and
parts of China. The history of Ohkuno is listed below7.
1927: The Japanese Army bought Yperite (mustard) manufacturing equipment from France and
evacuated all the residents from Ohkuno, off the coast from Hiroshima
1929: The Army started producing chemical weapons on the island of Ohkuno and erased the
island of Ohkuno from the map
1931: Phosgene production started
1933: Lewisite and tear gas production started
1935: The Army built German style Yperite manufacturing equipment
1945 August 15th: Japan stopped all the chemical factories in Ohkuno (The same date that the
Japanese government accepted unconditional surrender, the Potsdam declaration.)
1945 August 16th: The Army ordered the destruction of evidence of chemical weapons including
documents
1946 May: The Allied Forces, under the command of the United States, dumped about 3,000 tons
of chemical agents and weapons into the Pacific Ocean
1947: The U.S. army burned and dissembled the factories of chemical weapons in Ohkuno
In the beginning of 1929, less than 100 people were employed in making chemical weapons.
However, the numbers of employees involved in chemical weapons production steadily climbed
to several hundred in 1935, and jumped to 5,000 in 1939. After the government erased the island
of Ohkuno from the map, people were not allowed to take photos or even draw pictures.
Furthermore, people in the train had to shut the blinds while the train passed next to Ohkuno
Island.8
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The production of chemical weapons is listed in Table 4. The table indicates that factories in
Ohkuno had the capacity to produce chemical weapons, particularly blister agents such as
Yperite and Lewisite. For unknown reasons, the total production in 1944 suddenly decreased.
Table 4: Production per month in the island of Ohkuno (metric tons)
(The number in 1944 is total production that year)
1928
-
29-30
-
31
-
32
-
33
2
34
60
35
15
36
10
37
30
38
30
39
70
40
120
41
42
170
43
169
44 total
114
(0.1)
-
-
-
-
-
-
-
90
160
100
100
1130
100
102
43
-
-
-
-
-
-
-
-
5
130
180
160
180
100
1
-
-
-
-
-
4
3
5
150
210
120
170
150
194
87
Hydrogen
cyanide
-
-
-
-
-
-
-
-
-
-
20
5
113
103
1
13
Diphenyl
cyan arsine
Chloroacetop
henone
-
-
-
-
-
6
20
15
35
310
200
175
306
433
246
91
-
(0.02)
1
-
2
2
1
2
-
7
3
-
22
7
5
-
German type
Yperite
French type
Yperite
German type
cold Yperite
(not frozen)
Lewisite
Source: The History of Toxic Gas Island [Dokugasutou no Rekishi]p.39
After the end of WWII, as shown earlier, under the command of the United States the Allied
Forces, dumped about 3,000 tons of chemical agents and weapons into the Pacific Ocean from
the island of Ohkuno alone. The details of sea-dumped chemical weapons from the island (in
tonnes, or metric tons) are listed below.9






Toxic liquid: 1,845 tonnes, which was directly sent to ships by using long pipe
Toxic liquid can: 930 tonnes
Vomiting (Sneezing) agents: 990 tonnes
Riot control agents: 7 tonnes
60 kg toxic gas projectiles: 13,272
10 kg toxic gas projectiles: 3,036
These chemical weapons dumped into the Pacific Ocean from the
island of Ohkuno are regarded as the largest amount of dumping
in Japan. While loading the toxic material to the ships, some
material leaked from the pipes, accidentally causing severe
injuries to workers.10
The figure to the right shows a paper cover of a disposal report of
toxic gas weapons found by Prof. Yoshimi in 1991 at the National
Archives of Maryland (Source :Toxic Island Research Center
official website). The picture describes the disposal of chemical
munitions from the island of Ohkuno to the Pacific Ocean.
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Original Photographs from Ohkuno Island
French Style Yperite factory in Ohkuno
Source: Toxic island research center http://homepage3.nifty.com/dokugasu/
Left Picture: Chemical weapons at the north shore of Ohkuno
Right Picture: Ship departure with chemical weapons from Ohkuno
Source: Toxic island research center http://homepage3.nifty.com/dokugasu/kaihou06.html
Left Picture: Chemical weapons storage in Ohkuno
Right Picture: Power plant in Ohkuno
Source: Pictures taken by Ryo Sato, Global Green USA
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2. Potential Risks from Disposal in the Ocean
2.1 Reported Injuries and Deaths
According to the result of research conducted by the Japanese Ministry of the Environment
reported in 2004, since 1945 there had been 822 incidents including the discoveries of chemical
weapons, incidents of human health consequences and the government‟s handling of chemical
weapons11 Some chemical weapons have been discovered after the Ministry reported the
research in 2004, bringing the total to more than 822 incidents. During the past 65 years, more
than ten people have died and more than 400 people suffered ill effects from these chemical
weapons. The deaths all relate to chemical weapons dumped in Japanese waters.
Table 5 shows the discoveries of sea-dumped chemical weapons that have caused human injuries
after the Second World War. The table indicates the location, date, type of chemical weapons
and victims of discoveries.
Table 5: Discoveries of sea-dumped chemical weapons and human injuries
Location, Prefecture
Mutsu-bay, Aomori Pref.
Kuji-bay, Ibaraki Pref.
Kashima-bay, Ibaraki
Pref.
Off Choshi, Chiba Pref.
Date
April, 1954
Chemical Weapons
Mustard
Injuries and deaths
At least 1 injury
1962
September 5th, 1968
11 injured
2 injured
August 27th, 1963
July 2nd, 1985
Gas projectiles
Unspecified 10
projectiles
Mustard projectiles
Unspecified iron pipes
March 26th, 2002
Mustard
1 died, 1 injured
Several children
injured
3 injured
April 1st, 1951
June 24th, 1954
19 kg of toxic gas
2 projectiles of Mustard
4 died
6 injured
June 29th, 1954
6 injured
January 25th, 1970
March 1970
60kg of Mustard
projectiles
300kg of Mustard
projectiles
Mustard projectiles
Unspecified
Unspecified
300 kg of Mustard can
Mustard projectiles
Mustard projectile
11 of Mustard projectiles
November 12th, 1974
September 3rd, 1976
One Mustard projectile
Mustard
1 injured
5 injured
September 13th, 1957
1958
September 26th, 1967
September, 1967
January 17th, 1970
10 injures
17 toxic symptoms
5 injured
Several injured
5 injured
10 injured
9 injured
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Location, Prefecture
Off Futtsu, Chiba Pref.
Hamana-ko lake,
Shizuoka Pref.
Kawachinagano (pond),
Osaka Pref.
Off Himeji, Hyogo Pref.
Off Ohkuno-shima
island, Hiroshima Pref.
Date
June 19th, 1975
September 7th, 1975
October 10th, 1975
November 1975
July 15th, 1978
August, 1945
July 16th, 1947
Chemical Weapons
Mustard pipe
Mustard pipe
Unspecified
Mustard projectile
Mustard projectile
4 to 5 cans of Mustard
Unspecified steel drum
June 1st, 1952
September, 1945
Can of Mustard
Mustard, Lewisite
February to April, 1956
1946, 1947
April 18th, 1972
77 of White Phosphorus
Mustard, Lewisite,
Diphenylcyanoarsine
Unspecified
20 kg tank of hydrogen
cyanide
1 toxic gas tank
1 toxic gas tank
1 tank of hydrogen
cyanide
Unspecified 2 steel drum
August 26th, 1952
30 projectiles of Mustard
13 injured
February 1957
March 1961
July 1950
Mustard projectiles
2 shells
Mustard can
Several injured
2 injured
11 injured
May 1968
1 toxic gas tank
Several injured
April, 1954
Mustard projectile
3 injured
April, 1954
March 16th , 1954
Mustard projectile
50 kg of Mustard
projectile
1360 Mustard projectiles,
1137 toxic projectiles
3 injured
3 injured
April 1951
May 29th, 1958
May 11th, 1968
February 22nd, 1970
December 22nd, 1970
Ohkuno-shima island,
Hiroshima Pref.
Suounada, Yamaguch
Pref.
Off Komatsu-shima
island, Tokushima Pref.
Off Omishima Higai,
Ehime Pref.
Kanda bay, Fukuoka
Pref.
Off Beppu bay, Oita
Pref.
1955-1956
Injuries and deaths
2 injured
2 injured
1 inured
2 injured
1 injured
Several injured
2 died, several
injured
Several injured
1 died, 2 to 3 children
injured
Several injured
1 died, 90 injured
1 injured
1 died, 27 injured
1 injured
Several injured
4 injured
Several injured
32 injured
Source: The Japanese Ministry of the Environment official website
http://www.env.go.jp/chemi/report/h15-02/006.pdf
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2.2 Chemical Weapons Washing Ashore
In 2004‟s report, the Japanese government only documented the following three incidents of
accidental retrieval of chemical weapons washing ashore (Table 6, below) out of the total of 822
incidents, mostly shown also in Table 5. As discussed above, chemical weapons still threaten
populations in the vicinity of the dumping sites and residents have to beware.
Table 6: Documented incidents from chemical weapons washing ashore
Date
Location
Agent
Consequence
April 1951
Choshi, Chiba Pref.
19kg of toxic gas
4 people died
March 1961
Suounada, Yamaguchi Pref.
2 projectiles
2 policemen injured
February 1997
Ohkuno-shima, Hiroshima
Pref.
35 pipes of Akazutsu
(Diphenylarsinic acid)
No injury
Source: The Japanese Ministry of the Environment official website
3. Chemical Weapons in the Pacific Ocean
On January 29th, 1944, the Japanese Army announced “the outline of chemical war preparation”
against the United States. This document outlined retaliation against the U.S. by using chemical
weapons, in case the U.S. Army used chemical weapons. The locations of stockpiles were
decided by the Japanese government to be in Shanghai, Manila, Singapore, Truck Lagoon and
Sapporo, and Ujina. The precise amount of chemical weapons that came from each of these
stockpile locations is unknown, except in the case of Ujina, where the amount has been
specified.12 This raises the possibility that chemical weapons might have been dumped, also at
sea, not only in China but also in other Asian and Pacific countries.
Furthermore, statistical data also shows the possible existence of chemical weapons in other
Asian countries. According to Yoshiaki Yoshimi, a professor at Chuo University, 6,616 tons of
chemical weapons were produced in Ohkuno-island. However, only 3,647 tons have been found
since the end of the Second World War. This implies that nearly 3,000 tons were somehow
disposed of in other Asian and Pacific countries, in order to fight the Allied Forces.13
Because of the undiscovered chemical weapons, another problem is the issue of sunken ships.
There is a possibility that chemical weapons are inside the sunken ships. During the Second
World War 7,240 Japanese commercial ships alone were sunk14 -- most of them in the Pacific
Ocean. In the South Pacific 3,800 vessels were sunk, over 85% of them under the Japanese flag,
according to Sea Australia, an Australian based business providing environmental/marine
pollution solutions.15 If they are present, chemical weapons could leak and massive disasters
could also come about from large amounts of leaking oil in the future.16
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The picture to the left shows a gas mask resting near
the Japanese sunken ship, Nippo Maru, in Truk Lagoon.
Truk Lagoon is located in the central Pacific Ocean.
(Source: Photo taken by Rod Klein
http://www.scubadiving.com/travel/2007/07/worlds-bestwrecks)
Figure 3: World War II sunken vessels combining AMIO and SPREP databases
Source: The Global Risk of Marine Pollution from WWII Shipwrecks
4. Case Study: Offshore of Choshi Bay
Choshi is one of the cities in Chiba Prefecture, located about 100 km east of Tokyo. Choshi is
famous as a fish market and the city ranks number one in Japan in terms of the amount of fish
caught annually. Offshore of Choshi Bay was one of the biggest chemical dump sites in Japan.
The Allied Forces dumped 450 tons of chemical weapons in depths of 100 – 200 meters between
October 1945 and May 1946.17
According to the Japanese Ministry of the Environment, more than 600 incidents were reported
to the government, shown by the red circle around one of the blue squares in Figure 4, and more
than 50 people have suffered from the incidents around the Bay.18 More than two thirds of the
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incidents occurred in the 1970s and in 1972, people discovered chemical weapons and agents on
66 occasions. However, no incident was reported to the government from 1993 to 2001.19 In fact,
it is reported that fishermen in the bay area have been throwing the discovered chemical weapons
back to the ocean without notifying the government. The fishermen are worried about a rumor
that the fish from this region might be polluted by the weapons, which would affect their
business. This would cause a larger scale of chemical material scattering.
Figure 4: Chemical Weapons Incidents Reported to the Japanese Government
246
220
22 3
0
2
1995-1999
2000-2002
1985-1989
1980-1984
1975-1979
1970-1974
14
1990-1994
99
1951-1969
250
200
150
100
50
0
Break down of the 606 incidents, offshore
of Choshi
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5. Legal Considerations
On April 28th, 2009, the Japanese Ministry of the Environment held a press conference, during
which it stated the Ministry‟s current approach to dealing with sea-dumped chemical weapons.
“The Cabinet decided that the Ministry of the Environment has a responsibility for
the dumped chemical weapons on the land. However, it is still not clear whether and
how to deal with chemical weapons from water (- ocean, lakes and rivers.)”
(April 28, 2009. Press conference with the Minister of the Environment, Saito)20
The above statement implies that the Japanese government still does not have a clear method to
remedy the problem of sea-dumped chemical weapons inside their country. As discussed in this
paper, there is a high possibility that chemical weapons will be discovered inside and outside of
Japan. To minimize the threats of chemical weapons discovery from water to the human health,
the government should make specific guidelines relate to sea-dumped chemical weapons.
6. Conclusion
Since the Second World War, there have been over 820 discoveries of dumped chemical
weapons around Japan. The former Japanese government built chemical factories almost
entirely in the island of Ohkuno and disposed of chemical weapons not only in China but also all
around Japan, leading to a total number of 30 declared disposal sites.
During recent years, the Japanese government has researched and updated the disclosed
information on chemical weapons issues for the public, which could contribute to mitigating
potential negative impacts on humans and the marine environment, especially on fishermen who
are more likely to encounter chemical weapons. However, records on the dumped chemical
weapons still remain highly incomplete, resulting in a high possibility that Japanese will
accidentally discover and could be harmed by chemical weapons.
In addition, to prevent the current situation worsening, for example in Choshi where fishermen
have been throwing the discovered chemical weapons back to the ocean, the Japanese
government should draft relevant laws promptly and also minimize the possibility of the
chemical weapons munitions scattering further. In light of the potential risk these chemical
weapons pose both to the environment and local communities not only in Japan but also in the
Pacific Ocean, further research and action is urgently needed.
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Endnotes
1
Hatsuichi Murakami. The History of Toxic Gas Island [Dokugasutou no Rekishi]. October
2003.
2
Yoshiaki Yoshimi. I was born in the village of toxic gas [Boku ha Dokugasu no Mura de
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