Almost seventy years ago, a group of Polish children arrived in the coastal village of Darłowo for summer camp. As some children splashed in the cold, turbid waters of the Baltic Sea, others played around an old, corroded barrel they found lodged on the beach, blissfully unaware of the looming threat leaking from within. 

A few hours after being exposed to the barrel’s brown-black liquid, over 100 children began feeling sick. The culprit? Mustard gas. 

According to the Centers for Disease Control and Prevention, symptoms of mustard gas exposure include red, itchy skin that can turn into painful yellow blisters, difficulty breathing, runny or bloody nose, nausea, vomiting, eye irritation, and even temporary blindness. The blisters can lead to deep burns and take weeks to heal. According to case reports, four of the Polish children ultimately suffered irreversible eye damage.

It was a national scandal, and the public demanded answers. So the government convened a panel of experts to find out what was going on and how to fix it. They concluded that the barrel had been a sulfur mustard bomb—one piece among over a million tons of obsolete conventional and chemical warfare munitions dumped in the oceans after World War I and II—washed ashore by the natural flow of currents over time. 

The panel’s solution was to spread bleaching powder on the beach to neutralize the mustard gas. One of the experts in that commission, Krzysztof Korzeniewski, used to tell that story to his marine chemistry students at the University of Gdańsk in Gdańsk, Poland. The lecture sparked a lifelong passion for one of the students, Jacek Beldowski, who went on to devote his career to investigating defunct chemical weapons abandoned in the ocean. 

These discarded warfare relics are disintegrating with every passing second, with the potential to pollute everything they touch. Yet the solutions to stop that scenario are still in the early stages—and the political will to use them lackluster.

The dangerous, global legacy of dumped chemical munitions

There are roughly 150 to 300 sites with dumped chemical weapons worldwide, according to Beldowski, who now works as a professor of marine chemistry and biochemistry at the Polish Academy of Sciences. That number includes around 50 sites along American coastlines, with a significant proportion in Hawaii. “They’re in every ocean and almost in every sea,” he says. 

[Related: Researchers found signs of human pollution in animals living six miles beneath the sea]

In 2017, a group of researchers from the Middlebury Institute of International Studies in Monterey, California, calculated that the total amount of chemical munitions quietly lying on the ocean floor reached 1.6 million tons. That number only includes the weapons in known locations—which they believe is only 40 to 50 percent of the total number of sites. 

There is ample evidence that these chemical weapons are already leaking. Studies in the Baltic Sea have found toxic remnants in the tissues of sea stars, lobsters, and even commercial fish species. They’ve already taken a toll on fish populations off the German coast, says Claus Boettcher, the director of Germany’s Program on Underwater Munitions. 

“We have a serious suspicion of an effect on the reproduction rate of cod, the most commercial species in Europe,” he says, “because most of the cod’s main reproduction areas are exactly in the same areas where the highest munitions contamination concentrations are.” 

If these weapons keep leaking—or the volume of the leak increases—they could endanger the survival of organisms that are already struggling to adapt to a warmer, polluted, and acidifying ocean. 

But the effects of these noxious conflict artifacts extend beyond sea creatures, and the Darłowo children were just one example. Between 1998 and 2009, almost 2,000 encounters with abandoned munitions occurred in the waters around Belgium, France, Germany, Ireland, the Netherlands, Spain, Sweden and the United Kingdom, according to the European OSPAR commission, which works to protect the northeastern Atlantic Ocean. 

About 60 percent of the incidents involved fishermen pulling munitions up in their nets. In one particularly disturbing instance, three Dutch fishermen were killed by a WWII-era bomb that exploded when they hauled it aboard their ship. 

In Germany alone, authorities annually record between one and five cases of people at beaches getting burned with highly flammable white phosphorus (it can be mistaken for amber), a byproduct of chemical weapons, says Boettcher. 

The underwater dumpsites are also becoming an increasing hurdle for the development of climate change adaptation efforts, from the construction of better flooding-prevention systems to the installation of wind farms.

“Seventy years ago, we didn’t think that we’d be building offshore wind farms and that we would have offshore telecommunication cables going all over the place,” says Margo Edwards, who works as the director of the applied research laboratory at the University of Hawaii. “As we have moved out into the ocean, we’ve come in conflict with the lack of foresight that we had in the 1940s, and now we have to deal with the problem.”

To understand how the ocean became a collection of chemical weapons dumpsites, we need to go back almost a century, to the First World War, when armies first began deploying mustard gas, an extremely abrasive chemical that burns the skin and inflames the eyes and throat. Despite signing a protocol in 1925 that prohibited the wartime use of chemical and biological weapons, the nations involved in World War II again used mustard gas and other chemical weapons on the battleground anyway. 

The end of the war left an arsenal of unusable chemical warfare, which, governments figured, wouldn’t hurt anyone in the depths of the ocean. Ships left the shores of Poland, Germany, the UK, Japan, and even the US, loaded with thousands of tons of chemical weapons and other objects like sea mines, bombs, torpedo heads, grenades, and ammunition. 

Some munitions were simply thrown overboard, according to the Middlebury group, while the majority were loaded as cargo onto ships that would then intentionally be sunk. One by one, toxic chemical weapons sank to the bottom of the sea. 

Finding dirty needles in a watery haystack

Until the late nineties, both the public and politicians turned a blind eye to the dumpsites, says Beldowski. In 1997, the Chemical Weapons Convention (CWC) treaty entered into force, which demanded nations destroy their chemical weapon stockpiles. But the treaty didn’t address what countries should do with the weapons created and dumped in the seas before 1972. 

Some activists and scientists were critical of the omission, so in 2004, the nine countries that share the Baltic Sea—where the majority of dumped munitions rest—created the first integrated European project to measure the environmental risk of the abandoned ordnance, dubbed MERCW

The MERCW group used sonar scanners to map the biggest dumpsite in the Baltic, the Gdańsk Deep. If they detected something in the landscape that resembled a weapon, they sampled water from the nearby area looking for one particular byproduct of degraded mustard gas, ethylene glycol. They found evidence of widespread contamination with warfare agents like Adamsite, sulphur mustard, tabun, chlorobenzene, and arsine oil. But it was a small project, so the sampling was patchy and the results inconclusive.

[Related: Manmade pollutants could be harming marine mammals more than we think]

Something didn’t sit well when Beldowski saw those results. The MERCW team had chosen to study several compounds, but only one possible byproduct of mustard gas. By that point, other researchers had identified at least 50 additional compounds that appeared as mustard gas and other chemical weapons degraded in the ocean. Additionally, he disagreed with how the sampling sites had been chosen. Sometimes, he argued, they were too far away from the potential weapon. 

By 2011, he had convinced the European Union to fund a new project that would search for pollution from warfare agents in sediments and determine if the contamination was spreading and reaching live organisms. 

That project became Chemical Munitions Search and Assessment, or CHEMSEA. It brought together an international team of some 200 researchers from 11 European institutions. They sampled 200 objects over three years and looked for contamination from all 50 possible compounds. 

Not only did they discover an undocumented dumpsite in the Baltic, but they found that on average, each remnant was polluting a larger area than initial models predicted, up to 250 meters, or nearly three American football fields. In the dumping sites, the fauna and flora were close to non-existent due to the low concentrations of oxygen.

A corroded chemical munition sits at the bottom of the sea.
Leaking munitions can deplete oxygen levels, causing wildlife to abandon polluted sea-floor areas. Hawaii Undersea Research Laboratory

After that project, the North Atlantic Treaty Organization (NATO) asked Beldowski to follow up on his previous results. His team decided to create better, more reliable monitoring methods. Up to that point, discovering dumped chemical weapons was extremely expensive and time-consuming. Sonar would signal if something was hiding on the seafloor, but scientists had to actually go to each site with submarines to confirm it. A new international team representing 18 countries from all over the world got involved to develop tools that would make monitoring cheaper and more precise.

Beldowski thought that with cheaper ways to monitor what was going in the dumpsites, he could finally convince countries to pay attention to the problem. But he was wrong. 

“Their usual response is that you can just leave those things there because nothing has happened,” he says. “It’s like they think the problem will go away if they close their eyes.”

There are only three options to deal with these weapons, according to Beldowski: Leave the object alone if removing increases the risk of leakage; remove it if the corrosion is so severe that leakage is accelerating; or isolate the weapon, like the USSR did to Chernobyl’s reactors after they exploded. 

But there are about 50,000 tons of chemical munitions buried in the Baltic alone, and 190,000 tons more to the north in the Skagerrak Strait—millions of individual pieces, each needing a tailored solution.

The complicated solutions for dumped munitions remediation

To figure out what to do with each individual piece, in 2015, Beldowski started a series of projects called DAIMON I and II. The project created a set of “decision aid tools” to help countries decide what to do with which objects, including a detailed catalogue of all the known munitions dumped in the Baltic. 

The system allows decision-makers to consider every possible variable of an individualized weapon—its size, dumping year, exact location, the strength of currents in the area, among others—to determine if it should stay in the ocean, be closely monitored, or be removed immediately. 

In the Baltic, where shallow, cold waters hardly move, “probably lots of those munitions are either totally corroded or are in such a situation like covered with sediments that they really can stay there,” explains Beldwoski. 

“But maybe 10 percent of it is still dangerous and should be either monitored or taken out. And only then you can start calculating costs.” The problem is that, according to the team’s calculations, scientists only have enough data for 4 percent of the known munition dumpsites, mostly in the Baltic. 

These solutions are also not universally applicable: Fixes for weapons in Northern Europe might not be useful for those buried in the deeper, warmer, and restless Pacific waters, says Margo Edwards, from the University of Hawaii.

Edwards suspects that in the islands, where she says there are about 3,000 tons of dumped munitions, many chemical weapons imploded a long time ago, crushed under the higher pressure of deep waters. As a result, the contaminants’ concentration is an order smaller than those found by Beldwoski’s team in Europe. 

“Where I live, life has grown over the munitions that were disposed of in the 1940s. Removing these from shallow waters involves more damage because they’ve become part of the habitat,” she says. 

Sea creatures have attached to old chemical munitions in Hawaii
Dumped munitions can become part of wild habitats, complicating their removal. Hawaii Undersea Research Laboratory

As an alternative, people are working on a technology “where you drill a hole into the munition and drain all the internal stuff, leaving the munitions to be the habitat for the animals that have already grown up on it.”

Other solutions require the weapon to be taken out of the ocean and incinerated at extremely high temperatures in a closed space, so the gases won’t reach nearby people, explains Benedykt Hac, an oceanographer working for a Polish company developing these technologies. 

Hac says that most removal technologies are being developed by small companies that can’t scale their solutions to an industrial level, so removing these objects remains expensive: about 30,000 euros per piece. To do so, he says, they’ll need governmental support, which so far remains elusive.

In some countries like Sweden and Denmark, there’s less public pressure to clean up the waste, which often drives action, says Boettcher. While some governments are working to deal with the problem, overall, he says, there’s no unified consensus among all countries involved.

Boettcher fears that leaving this problem unaddressed could potentially harm these countries’ economies, not only because it could hurt the sustainability of their fishing industries, but also because in the last couple of years, some companies have started exploring the possibility of taking legal action. 

Since governments are reluctant to take responsibility for these munitions, he says, wind farm, drilling, and cable companies that use the seabed often have to remove the toxic munitions themselves—or spend additional money to avoid passing through those sites. “I expected that they would do it last year. But I believe in the near future, these large enterprises will start to go to court,” he says.

One thing is certain: The clock is ticking. In 2015, researchers from the Polish Naval Academy threw into the ocean hundreds of pieces of the same kind of metal used in the bombs, shells, and munitions that had been dumped after the two World Wars. Two years later, they recovered the metal and created a model to calculate how fast these objects are disintegrating. 

They found that barrels are probably already completely corroded, because they weren’t as thick as other objects. Bombs will erode sometime between 2020 and 2030, according to their model. “It’s quite soon, and of course, this is only a simulation,” says Beldwoski. “We may never be sure, but we should be assuming the worst-case scenario.”