Chemical warfare agents (CWA) represent environmental legacy contaminants as production and subsequent dumping of CWA typically occurred decades ago. Despite being legacy contaminants it is not only the location and amounts of ocean dumped CWA that is unknown due to their status as illicit compounds, but their inherent properties with regard to physicochemical, fate, long-term human and environmental toxicity properties have not been characterized comprehensively.After World War II (WWII) approximately 32,000 t of chemical weapons, containing about 11,000 t of highly toxic agents, were dumped in the Bornholm Basin, east of the island of Bornholm in the southern Baltic Sea.