Chemical Weapon Munitions Dumped at Sea: An Interactive Map

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August 1, 2017 • Updated September 7, 2017
Ian Wilkinson

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Munitions History

In the decades following World War I, and even more so during and after World War II, at least four major powers disposed of massive quantities of captured, damaged, and obsolete chemical warfare (CW) material by dumping them into the oceans. The jettisoned material consisted either of munitions containing chemicals (such as artillery shells, mortar rounds, or aerial bombs) or chemicals stored in large metal containers or encased in concrete. Shells and bombs were sometimes jettisoned unfettered, but more often were loaded as cargo onto ships that were sunk by opening their seacocks, by naval artillery fire, or torpedoes. (1) Because those sunken ships tended to settle on the seabed largely intact, the CW material they contained remained within a small area. Unfettered material, on the other hand, may be widely dispersed by currents, tides, and other forces. (2) In those times, the disposal crews did not give much consideration to the safety and environmental implications of sea-dumping CW materials.

The records of some operations, including listings of where the dumping occurred, and the types and quantities of the dumped material, were well kept. For example, according to United States (US) Department of Defense reports, the US military alone dumped CW agents and munitions in oceans throughout the world on at least 74 occasions between 1918 and 1970. (3, 4) Other dumping was done haphazardly with no or minimal preserved records. The USSR (and now Russia), in particular, has provided few records to the international community of its sizable chemical dumping activities. Russia has admitted that “at least 160,000 tons of chemical weapons may be settled on the seabed of Russian seas, posing a grave threat to ecology and the health of man” (5), which demonstrates the potentially enormous problem posed by Soviet ocean-dumped chemical weapons material. Similarly, 302,857 tons of CW munitions were left over in Germany and the United Kingdom (UK) after World War II, most of which were eventually dumped in the oceans. (6,7) However, because of sparse records, the total quantity of CW material discarded at sea will never be known precisely, but does include at least 1.6 million tons (this quantity was determined from the summation of all known quantities in the data collected for this map).

National environmental legislation and international environmental protection agreements emerged as public environmental concerns rose in the 1960s, which caused the disposal of CW agents at sea to become increasingly rare. A major development occurred in 1969, when the US National Academy of Science recommended that ocean dumping be discontinued as a method of disposing chemical agents and munitions. (8) Despite these efforts, CW ocean dumping did not end until after the 1972 Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter came into force in 1975, which banned the practice of ocean-dumping of CW materials. (9) Currently, 87 States are Parties to what is commonly called the London Convention.

Threats and Hazards

CW agents lodged on the seabed present three types of threats to the world. First, many contain explosives that can self-detonate without warning. Second, some human activities, such as fishing, dredging, and pipe laying in areas laden with dumped CW agents, may result in humans being exposed to CW agents. (10) Because chemical weapons are designed to cause human casualties, they can burn the skin, injure the naso-pharyngeal and gastrointestinal tracts, and close down the nervous system (see below) of exposed, unsuspecting workers. (11) Third, CW agents and their degradation products can cause direct and indirect damage to the marine environment. There is little concrete data on how and to what extent CW agents may cause environmental harm. It is feasible, however, that the damage to primary producers in the marine environment, as well as the food webs of which they are members, could be substantial. Though several investigations have tried to answer these questions, many have discovered that the factors that contribute to the degradation and spread of CW agents – namely currents, ocean temperature, and depth – vary greatly between dumpsites. (12)

CW agent disposal sites have created a latent public health hazard with unknown but potentially serious environmental consequences. In areas of substantial dumping, such as off the coast of Japan and in the Baltic and Adriatic Seas, a large number of injuries have resulted from exposures to accidentally recovered CW agents. In most cases, CW materials are ensnared in fishing nets or accidentally disturbed during dredging operations. For example, Italian scientists have documented 232 instances of mustard-related injuries, including five deaths, suffered by Italian fishermen in the waters off Molfetta (near Bari) between 1946 and 1997. (13) Bioaccumulation of hazardous levels of arsenical chemicals in the local fish population, likely derived from the blister agent Lewisite, has also been observed as recently as 2005. (14)

The Italian experiences in the Adriatic demonstrate that a better understanding of the locations of the dumpsites, as well as the status of the materials within them, is needed to gauge the risk posed by undersea CW materials. Following decades of advances in ocean science and technology, human oceanic activity is increasing and expanding to deeper waters. Consequently, CW dumpsites once thought impossibly remote to reach are becoming increasingly accessible and dangerous to unaware explorers and workers. These problems have drawn considerable attention and concern by both the public and its elected representatives. This has resulted in the commissioning of research activities and the publication of official reports documenting the extent of dumping activities undertaken in the 20th century and their potential for causing harm. For example, in 2006 the US Congress enacted legislation requiring the Secretary of Defense to review historical records and report annually on “the number, size, and probable sites where the Armed Forces disposed of military munitions in coastal waters.” (15) International initiatives, such as Baltic Marine Environment Protection Commission (also known as the Helsinki Commission or HELCOM), have also been created to investigate these sites.

Readers should keep in mind that information about most ocean dumpsites, especially Russian ones, is incomplete and that there is only information on about (we estimate) between 40 and 50% of the total number of sites. The sites that are best known, and mapped, are those located in the Baltic Sea and North Atlantic, mostly because of accurate records and recent surveys having been undertaken in preparation for natural resource exploitations and cable and pipeline laying projects. Chemical dumpsites in other areas, particularly the Pacific Ocean, remain largely undocumented. This project’s investigators will seek to continually update their map and related data base as new discoveries are made.

Chemical Arms Control and Disposal

Major powers, including the US, UK, USSR, Germany, Japan, and France, manufactured massive quantities of CW agents throughout much of the 20th century. Their widespread use in World War I resulted in hundreds of thousands of casualties. The horrors of CW use during the war stimulated diplomats to negotiate the 1925 Geneva Protocol, which is a multilateral international treaty banning the use of CW and bacterial agents in armed conflict. However, the Geneva Protocol has, since its inception, been considered a weak arms control treaty, as it has no provisions for forbidding State Parties to develop and store chemical weapons, for verifying that nations are in compliance to the treaty, or levying sanctions if they are not. Further, it makes no mention of eliminating chemical weapons. (16)

In the 1980s, countries began to draft a stronger chemical arms control convention, which was realized after the 1993 Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction, more generally known as the Chemical Weapons Convention (CWC), entered into force in 1997. One of its main provisions requires its State Parties (currently 188 with an additional 2 signatories) to destroy all existing CW stockpiles and renounce any future development, production, stockpiling, or use of chemical weapons. (17) Notably, the CWC is silent with respect to the remediation of CW agents and munitions dumped in the seas prior to 1972.

With few exceptions, nations that previously possessed CW programs now belong to the CWC and thus are faced with the problem of disposing the remnants of their programs. As of this update, only four CW-possessing countries, Albania, South Korea, India, and Libya, have declared complete disposal of their chemical weapons (18) (the Organization for the Prohibition of Chemical Weapons [OPCW] stated in 2014 that Syria’s weapons had also been destroyed, but that now appears uncertain). (19) The major possessors, Russia and the US, are not likely to be in that position until the early 2020s. (20) All chemical weapons and related facilities in current and former possessor countries are located on terrestrial sites, hence are relatively easy to access. Japanese chemical weapons buried in China, however, are the major exception to this statement.

The situation regarding marine dumpsites is completely different than terrestrial sites. The CWC’s Article III, which deals with these sites, gives State Parties the option of declaring and/or destroying chemical weapons “dumped at sea” before January 1, 1985. Furthermore, State Parties are obligated to declare chemical weapons “dumped at sea” on or after January 1, 1985. John Hart notes that as of January 2000, “no formal declaration of dumping of CW in the high seas or in territorial waters has been submitted to the OPCW. (21) As far as we know, no such declaration has been made as of January 2008. While it is beyond the scope of our consideration, we note that options to address the problem are provided by Hart.

The opportunity exists for nations that are concerned about keeping the oceans pristine to take the lead to initiate a new multilateral effort to address the problem of CW materials dumped in the seas because the CWC is virtually silent about this issue.

The Data and Its Usage

The database, developed by CNS experts, is now available and cost-free to use. It is made available to whoever supports analysis of susceptible human populations, coastal industries, and marine ecosystems. The unified, nonpartisan database was developed to stimulate and support the efforts of national and international endeavors to address the serious threats posed to public health and the environment by CW material resting on the seafloor throughout the world. We would like to acknowledge Hakai Magazine for inspiring the additional map functionality in our most recent update to this page.

Please note that the geographic coordinate and depth data are often estimates based on approximate coordinates or geographical areas described in the literature. Please alert CNS map experts if this data is incomplete or inaccurate. Likewise, readers should note that the CW tonnage data is also an estimate, and, in some cases, may include the weight of the munitions and storage containers in addition to the agents they contain. All data fields that do not contain an entry are undetermined. Also keep in mind that while some points only refer to the sinking of a specific ship, many others describe a series of dumping related incidents that occurred over a longer period of time.

Most information in open literature is specific to a unitary actor (e.g. the US military) or a particular geographic region. (22) So far, no comprehensive database has been compiled for all marine disposal information. Reports on casualties caused by accidental exposure and on environmental damage are rare and when available, are limited to local areas. (23)


Information received by CNS after September 1, 2017

The U.S. Department of Defense (DoD) published a report in late 2016 that dealt with three topics: (1) research to date regarding the effects on sea-disposed munitions on the ocean environment; (2) the feasibility of removing or otherwise remediating munitions sea-disposal sites; and (3) recommendations for addition research and remediation or cleanup of munitions sea-disposal sites. We make the point that munitions include both conventional and chemical munitions, so we cannot differentiate between the two on our map. Keeping this in mind, the DOD’s research concluded that:

  • sea-disposed munitions, which have become part of the ocean environment and also provide critical habitat to marine life, do not pose significant harm when left in place;
  • removing or cleaning up munitions sea-disposal sites would have more serious effects on marine life and the ocean environment than would leaving them in place; and
  • the potential health effects from sea-disposed munitions in U.S. coastal waters appear to be minimal. (24)



  • Ian Wilkinson, CNS Intern Summer 2017
  • Raymond Zilinskas Ph.D. Principal Investigator (co-PI)
  • Anne Marie Steiger M.A. Google Map Development
  • David Steiger Google Map and Webpage Development
  • Caroline Ong, Performed initial investigation while serving as a CNS intern through the Davis United World College Scholars Program
  • Tamara Chapman M.A. former Co-Principal Investigator (co-PI)
  • Benjamin Brodsky Ph.D. former Assistant Investigator
  • Joshua Newman M.A. former Drafting & Technical Development expert
  • Peter G. Brewer, Ph.D., Consultant, Scientist at the Monterey Bay Aquarium Research Institute (MBARI)


(1) US Arms Control and Disarmament Agency, “Special Study on the Sea Disposal of Chemical Munitions,” 1993, p. 5-20.
(2) John Aa Tørnes, Øyvind A Voie, Marita Ljønes, Aase M Opstad, Leif Haldor Bjerkeseth, Fatima Hussain, “Investigation and Risk Assessment of Ships Loaded with Chemical Ammunition Scuttled in the Skagerrak,” Norwegian Defense Research Establishment (FFI), November, 2002, p. 13-21.
(3) Program Executive Officer-Program Manager for Chemical Demilitarization, Chemical Stockpile Disposal Program: Chemical Agent and Munition Disposal. Summary of the US Army’s Experience, SAPEO-CDE-IS-87005, (Aberdeen Proving Ground, Maryland, September 21, 1987).
(4) US Army Research, Development, and Engineering Command, Off-Shore Disposal of Chemical Agents and Weapons Conducted by the United States (Aberdeen Proving Ground, MD, 2001).
(5) Interfax, “Ministry: ‘Tonnes’ of chemical weapons ‘buried’ at sea,” Moscow, December 7, 1995.
(6) David M. Bearden, U.S. Disposal of Chemical Weapons in the Ocean: Background and Issues for Congress (Washington, DC: Congressional Research Service, May 24, 2006).
(7) Fredrick Laurin, “Scandinavia’s underwater time bomb,” Bulletin of the Atomic Scientists, Vol. 47 (2), p. 11.
(8) National Academy of Sciences, Disposal Hazards of Certain Chemical Warfare Agents and Munitions (Washington, DC: National Academy Press, 1969).
(9) International Maritime Organization, “London Convention 1972,”
(10) John Aa Tørnes, Øyvind A Voie, Marita Ljønes, Aase M Opstad, Leif Haldor Bjerkeseth, Fatima Hussain, “Investigation and Risk Assessment of Ships Loaded with Chemical Ammunition Scuttled in the Skagerrak,” Norwegian Defense Research Establishment (FFI), November, 2002, p. 13-21.
(11) US Arms Control and Disarmament Agency, “Special Study on the Sea Disposal of Chemical Munitions,” 1993, p. 5-20.
(12) Peter G. Brewer, and Noriko Nakayama, “What Lies Beneath: A Plea for Complete Information,” Environmental Science & Technology (2008), p. 1395-1396.
(13) G. Assennato, D. Sivo and F. Lobuono, “Health Effects of Sulfur Mustard Exposure among Apulian Fisherman,” Noblis Inc. (1995),
(14) E. Amato, L. Alcaro, I. Corsi, C. Della Torre, C. Farchi, S. Focardi, G. Marino, and A. Tursi, “An Integrated Ecotoxicological Approach to Assess the Effects of Pollutants Released by Unexploded Chemical Ordnance Dumped in the Southern Adriatic (Mediterranean Sea),” Marine Biology, Vol. 149 (2006), pp. 17-23.
(15) 109th US Congress, “John Warner National Defense Authorization Act for Fiscal Year 2007,” Public Law 109-364, Section 314, October 17, 2006.
(16) “Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare (Geneva Protocol),” US Department of State, updated 25 September 2002,
(17) OPCW, “Convention on the Prohibition of Development, Production, Stockpiling, and Use of Chemical Weapons and on Their Destruction,” Organization for the Prohibition of Chemical Weapons, 29 July 2005,
(18) OPCW Conference of the States Parties, “Report of the Third Special Session of the Conference of the States Parties to Review the Operation of the Chemical Weapons Convention,” Organization for the Prohibition of Chemical Weapons, 19 April 2013.
(19) OPCW Executive Council, “Note by the Director-General: Progress in the Elimination of the Syrian Chemical Weapons Programme,” Organization for the Prohibition of Chemical Weapons, 24 July 2017.
(20) “Report of the Third Special Session of the Conference of the States Parties to Review the Operation of the Chemical Weapons Convention,” Organization for the Prohibition of Chemical Weapons, 19 April 2013.
(21) John Hart, “A review of sea-dumped chemical weapons,” paper presented at the “The Environment and the Common Fisheries Policy, Threats to and Constraints on Sustainability” forum, 27 January 2000, The Royal Society, London, Great Britain.
(22) J. Beddington and A.J. Kinloch, Munitions Dumped at Sea: A Literature Review, (London: Imperial College Consultants, June 2005).
(23) The mapping relies on a Keyhole Markup Language (KML) file, which utilizes features and programs created by Google™.
(24) United States Department of Defense, Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics, Research Related to Effect of Ocean Disposal of Munitions in U.S. Coastal Water. Report to Congress, Washington, D.C, November 2016.

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