Toxicological consequences of sea-dumped munitions

Since World War I, considerable amounts of warfare material have been dumped at seas worldwide. After more than 70 years of resting on the seabed the metal shells of these munitions are corroding, such that  different kinds of chemicals leak out and distribute in the marine environment. Energetic compounds such as TNT (2,4,6-trinitrotoluene) and its derivatives are known for their toxicity and carcinogenicity, thereby posing a threat to the marine environment. Toxicity studies suggest that chemical components of munitions are unlikely to cause acute toxicity to marine organisms. However, there is increasing evidence that they can have sublethal and chronic effects in aquatic biota, especially in organisms that live directly on the sea floor or in subsurface substrates. Moreover, munition-dumping sites could serve as nursery habitats for young biota species, demanding special emphasis on all kinds of developing juvenile marine animals.

While the mechanism of toxicity and carcinogenicity of TNT and its derivatives occurs through its capability of inducing oxidative stress in the target biota, we found that TNT can induce the gene expression of carbonyl reductase in blue mussels. Carbonyl reductases are members of the short-chain dehydrogenase/reductase (SDR) superfamily and provide a defense mechanism against oxidative carbonyl stress as a consequence of reactive oxygen species (ROS) derived lipid peroxidation. After a bioinformatics approach and molecular cloning of the carbonyl reductase gene, we could show in both laboratory and field studies that TNT induces a strong concentration- and organ-dependent gene induction in the blue mussel. Carbonyl reductase may thus serve as a biomarker and early warning system for TNT exposure in marine systems

Unfortunately, munition chemicals may also enter the marine food chain and directly affect human health upon consuming contaminated seafood. While uptake and accumulation of toxic munition compounds in marine seafood species such as mussels and fish have already been shown, a reliable risk assessment for the human seafood consumer and the marine ecosphere is lacking and has not been performed until now. In this talk we present the landmarks for a risk assessment for the marine ecosphere as well as for humans who consume seafood contaminated with munition chemicals. We hereby follow the general guidelines for a toxicological risk assessment of food as suggested by authorities.