Germany's rusting sea munitions are a toxic time bomb

Underneath the waves off Germany's northern coast, hundreds of thousands of bombs and other weapons are slowly deteriorating. This massive collection of conventional munitions, estimated at 1.6 million metric tons, is a remnant of wars fought in the past and the disposal of weapons in the aftermath of World War II. For many years, the material was left undisturbed, except when it posed an immediate threat of explosion.

However, as the metal casings begin to corrode, a new issue is arising. Many of these weapons were once used in combat, including mines, unexploded bombs, and lost ammunition. Yet, a significant portion of them were systematically dumped after Germany's surrender in 1945, as part of the Allies' strategy to dispose of Germany's extensive arsenal.

Once thought to be a significant explosive hazard, they have now transformed into an environmental threat.

According to toxicologist Edmund Maser from Kiel University, as these items corrode, chemicals seep into the marine environment and the creatures living there. Maser highlighted that these compounds are both toxic and carcinogenic to humans and marine life. One of the most dangerous compounds found in these old weapons is trinitrotoluene, or TNT, a common military explosive.

Scharsack from Germany's Thünen Institute of Fisheries Ecology found traces of TNT and its degradation products in dab fish. While the levels are minuscule, they are detectable in fish that live near old munitions hotspots. However, to date, there is no evidence that these toxins are causing immediate illness in fish. The fish appear healthy when examined, showing no signs of increased disease.

While the contamination in fish appears minimal and does not appear to be directly harming them, there is a concerning trend developing. Maser's team found liver abnormalities in over 50% of fish living near certain munitions dumping sites, compared to a normal rate of just 1-2%. Mussels also showed signs of oxidative stress, indicating that the chemicals are not only affecting fish but also other marine life at the top of the food chain.

Maser's research has even detected TNT-related compounds in tissue samples from two stranded whales, suggesting that these toxic substances are reaching the highest levels in the marine food web.

The question then arises: Are humans at risk from consuming seafood contaminated with these chemicals? Both Maser and Scharsack maintain that the current exposure levels pose no immediate threat to human health. While whales are exposed to these toxins more consistently through their diet and environment, humans are only exposed occasionally through seafood consumption.

According to Scharsack, it would take consuming large amounts of fish to reach potentially dangerous levels. "I'm still going swimming. I'm still eating fish," he stated confidently.

However, the situation is expected to worsen as more munitions deteriorate, increasing the release of these toxic substances into the water. The problem appears more severe in the Baltic Sea than in the North Sea, due to the latter's stronger currents and more frequent water exchange, which helps disperse pollutants. Maser's research indicates that this contamination is increasing steadily in the Baltic Sea, from around 2000 to 2022.

Although the levels are still low, they are on the rise, and Maser warns that over the coming decades, concentrations could potentially harm human seafood consumers.

Marine life is already under pressure from various human-made pollutants, such as microplastics, pesticides, and pharmaceutical compounds. Adding munitions to this list of contaminants presents a new challenge. Unlike many of these other pollutants, which have already been dispersed throughout the oceans, bombs and mines remain as physical objects that could potentially be salvaged and disposed of.

Germany has long removed munitions that posed immediate dangers, but it has only recently begun pilot projects for more systematic clearance to prevent environmental harm.

In a study published in July, researchers from GEOMAR identified 484 known or potential munitions piles in two areas of the Baltic Sea. However, out of the estimated 1.6 million tons of munitions in German waters, around 1.5 million tons have yet to be mapped. The main obstacle to clearing these munitions is their disposal and destruction.

While specialist companies can clear large quantities relatively quickly, the real challenge lies in the safe disposal and destruction of the recovered munitions. Germany is currently developing an offshore treatment platform to help increase disposal capacity, but this is a long-term solution.

Maser is investigating whether marine bacteria and fungi could eventually break down these munitions residues into harmless substances like CO2 and water. While this work is still at the laboratory stage and cannot replace physical clearance, it represents a potential solution for the future. Maser stresses that we need to act early, as waiting might mean that all these metal casings have corroded, leaving us with no chance to remove the munition compounds from the water.