In 2009, the Swedish public was shocked by a public TV documentary, which revealed how the Soviets had sunk chemical weapons in the Baltic as recently as 1992. Hidden-camera footage filmed from Swedish waters showed one such operation, in which the Soviet military was seen dumping containers of paralysis inducing gas and radioactive material straight into the sea.

More than by the act itself, the Swedes were outraged by the fact, which was initially revealed by investigative journalists and later confirmed by military intelligence, that some members of the Swedish government had been informed, as early as 1999, that toxic waste was being dumped near the island of Gotland, but had done nothing to prevent it.

In the early 1990s, Russia had to decide what to do with its vast arsenals of chemical weapons that were stored in former Soviet military bases in Latvia and Estonia — in particular, the largest stockpile of lethal agents, which was stashed in the Latvian port of Liepāja. At a time when the morals and the organisation of the Red army were crumbling, and without money to move or recycle the poison, the Soviet General Staff chose to ignore any concerns about the environment or the safety of Poles or Swedes. In a decision taken for purely economic reasons, they decided to dump the arsenal in the Baltic Sea.

Toxic soup

The results of their action quickly became apparent. Starting in the mid-1990s, there was a sharp increase in the incidence of lung and skin cancer among Swedish fishermen working between the islands of Bornholm and Gotland off Sweden’s southern coast. They were suffering from typical symptoms of exposure to mustard gas (sulphur mustard). However, non-experts had virtually no chance of identifying the agent that was source of the problem in the water.

Mustard gas is a virtually colourless liquid which has a “faint garlic or horseradish-type odour”. It can remain in the containers for decades, slowly leaking out into the environment and wreaking terrible consequences. Worse still, the corroded military containers will eventually break open, releasing massive amounts of lethal chemical warfare agents, and this is what is happening in the Baltic Sea.

At the Potsdam Conference in 1945 a decision was taken to get rid of a total of 267,500 tonnes of chemical munitions. The cheapest way to do this was to dump the arsenal in the Baltic Sea, mainly in the Bornholm Basin, which plunges to a depth of 100m, and the Gotland Deep, which reaches a depth of 459m in the Landsort Deep area.

All in all, the Russians dumped some 40,000 tonnes of all kinds of canisters and containers full of adamsite, mustard gas, phosgene, tabun, cyanide salts and prussic acid in an area approximately 2,800 sq km around the island of Bornholm. In 1945 in the strait of Little Belt, the British dumped 69,000 tonnes of tabun-armed artillery munitions and 5,000 tonnes of tabun and phosgene bombs. A year later, the Americans sunk 42 ships loaded with 130,000 tonnes of German chemical warfare munitions in the Danish straits. The German coast was further doomed when in the early 1950s, Soviet and East German forces dumped 6,000 tonnes of chemical weapons there. As for the coast of Poland, its greatest hazard comes from a large Soviet dump south of Gotland.

Burning strategic question

Do the Baltic states have any plan for neutralising the underwater chemical warfare arsenal? There is nothing to suggest so. Nor do any clear-cut policies exist on how to clean the sea waters of this terrible mixture of deadly toxins. Fortunately, the issue has been given an increasingly high priority. In November 2010, EU-financed explorations of the Baltic seabed began in an effort to assess the condition of dump sites and determine what should be done to neutralise the underwater chemical arsenals and prevent an ecological disaster.

Poland is leading a supranational project called Chemsea, which includes 11 research institutes from Poland, Sweden, Finland, Lithuania and Germany. A report by Helcom Muni, an ad hoc expert group specialising in dumped chemical munitions, is expected this year. But even the best military experts cannot predict what exactly would happen if the chemical agents were rapidly released from their corroded containers. Current thinking suggests the steel canisters used for storing chemical weapons will corrode slowly and that any leaks would release only minute amounts of toxic substances, which would then undergo relatively swift hydrolysis.

Scientists stressed that, being heavier than water, any leaked toxins would settle on the sea bottom. Moreover, the Baltic is not a high seismic activity area so barring physical damage, there seemed to be no cause for alarm. It was only the Russo-German Nord Stream Baltic gas pipeline project that triggered a major public debate on the possibility of a local – but massive – ecological disaster.

Still, officers at the Polish Navy say that it is not the pipeline or the chemical warfare dumps that pose the greatest risk. We often forget that the Baltic was also used as a dumping ground for all kinds of conventional weapons, including heavy munitions, air bombs, naval mines and artillery shells. If any of those ever explode, a chain reaction could cause horror on the Baltic beaches on a scale comparable with Chernobyl.

Until the Baltic states implement a coordinated policy to recover and neutralise dumped chemical munitions, the waters of the Baltic will continue to harbour a highly toxic threat and walking on Baltic beaches will continue to be a potentially deadly sport.