Chlorinated organic solvents - such as tetrachloroethene, trichloroethene and 1.1.1-trichloroethane - are the most frequently used compounds e.g. for degreasing in all branches of industries.
Due to their widespread use, their large consumption quantities (Fed.Rep.of Germ. 180 × 103 t/a) and their physical properties, these organic solvents are the most important point-source of groundwater contamination.
A serious case of soil, soil air and groundwater contamination by these organic solvents (maximum concentrations detected were 500 mg/kg, 7g/m3, 50 mg/l respectively) is reported, caused by the metal industry, rendering plant and paper production.
A special effect is the comparatively rapid degradation sequence of tetrachloroethene to trichloroethene to cis-1,2-dichloroethene and to vinyl chloride. Concentrations of cis-1,2-dichloroethene observed in groundwater were up to 1600 µg/l and of vinyl chloride up to 120 µg/l, respectively, although none of these substances were primary pollutants in the investigated area.
Results of laboratory tests give rise to the suggestion that degradation of chlorinated hydrocarbons in contaminated areas is mainly by microbiological means.
This effect is of special hygienic relevance, due to the fact that one of the metabolites, vinyl chloride, is known to be a human carcinogen and the polluted area (approx. 4 km2) is located in a catchment area of a waterworks.