Abstract: As a result of the disarmament of Germany after World War II, 65,000 tonnes of chemical munitions were dumped in the Baltic Sea. Approximately 13,000 tonnes was made up by active chemical warfare agents (CWAs) of which 11,000 tonnes were dumped in the Bornholm Basin east of Bornholm. Previous environmental risk assessments (ERAs) concerning the dumpsites are preliminary and lack knowledge of actual exposure and hazards. This thesis is the first scientific study to address the environmental risk of compounds actually present in the Bornholm dumpsite by obtaining novel acute and chronic ecotoxicity data to compare with recently measured environmental concentrations. A read-across analysis of toxicant-gene interactions caused by the detected CWAs in mammals was furthermore carried out in order to investigate potential new biomarkers of exposure. EC₅₀ values were successfully obtained for six CWAs from acute tests with Vibrio fischeri whereas a 21 day test with Daphnia magna was less successful due to high control mortality. The three most toxic compounds were α-chloroacetophenone, 1,4,5-oxadithiepane and thiodiglycolic acid having EC₅₀ values of 0.0112, 1.70 and 22.5 mg/L respectively. A conservative ERA for acute marine risk could not rule out a risk due to high risk quotients for all tested CWAs. The read-across analysis showed potential of three CWAs to interact with 20 genes present in fish (Danio rerio). The relevance of these as biomarkers of exposure needs further research. Finally, a weight of evidence analysis highlighted the need for more research to rule out or confirm the environmental risk found in this thesis. Recommendations are given on how to cover data gaps which may serve as input in the work of MODUM, HELCOM and the Danish EPA.

Language: English

Location: the Pavilion