The chemical warfare agents (CWAs) contained in these munitions include so-called blister gases like mustard gas (also known as sulphur mustard, the most widely produced during WWII) or nitrogen mustard, tear gases (like chloroacetophenone), nose and throat irritants (such as Clark I, Clark II and Adamsite), lung irritants (like phosgene or diphosgene) and nerve gases (such as tabun). These dumped chemical munitions may also contain certain amounts of explosives. It is assumed that the chemical munitions dumped in the Baltic Sea contained roughly 15,000 tonnes of CWAs.
These munitions pose a threat if the warfare agent inside is released. This can occur as the walls of the metal shells corrode. The extent of corrosion and the rate at which it is taking place are unknown, which raises concern among Baltic countries. The corrosion rate depends on various factors such as the material from which the munition is made, the wall thickness and the nature of the dumpinareas, including the deep-sea regions where dumpsites are located. Unaware of this risk, construction projects such as installation of wind farms or laying of cables and pipelines, as well as other sea-bottom activities such as trawler fishing a