Toxicological analysis of the content of military canteens buried for 70 years in the karst cave in Kočevsko, South-Eastern Slovenia

Abstract

Forensic examinations can be performed on well-preserved objects to detect material traces. A large number of objects were discovered in the cave Brezno v Debliških livadah, which were dumped in the cave in May and June 1945. Among the discovered material there were also military canteens (drinking bottles). Some canteens still contained liquids, and some even a semi-hard, gel precipitate. The liquid and precipitate from the analyzed canteens contained metals that were most likely leached from the metal containers. The corrosion of the canteens is indicated by the presence of a hematite mineral. The content of canteens contained some dissolved organic matter (Total Organic Carbon, TOC, in the liquid = 9.22 mg/l, in the liquid from extracted precipitate = 34.1 mg/l), some microbial biomass and relatively high nitrate concentrations (240 mg/l in liquid, 55 mg/l in extracted precipitates) and sulfate (18 mg/l in liquid, 836 mg/l in extracted precipitate). Bacterial indicators, Escherichia coli and enterococci, indicating faecal contamination of the canteens‘ contents, were not detected. The liquid and precipitate exhibited a similar degree of toxicity, about
20% inhibition of the bioluminescence of Vibrio fischeri. According to the Slovenian Rules on drinking water, the liquid with the present chemical properties is not suitable for human consumption. The results do not necessarily indicate that liquids were already toxic when the canteens were thrown into the cave, but the toxicity could have developed progressively due to (bio)chemical reactions and leaching of metals, in particular aluminum, from the canteens. In spite of the stable cave conditions to which canteens have been exposed, the observed parameters do not support long-term preservation of stable DNA for potential future forensic analyses.