Technical Committee Analytics

Derivation of ecotoxicological threshold values and records about insignificance threshold values for selected organic substances

Ecotoxicological threshold values (ÖSW) were specified for 5 substances (benzene, toluene, MTBE, benzo(a)pyrene, naphthalene) on the basis of the Predicted No-Effect Concentration values (PNEC) as laid down in the risk assessment reports of the European Union. They were compared to the insignificance threshold values (GFS) of the Länderarbeitsgemeinschaft Wasser (LAWA). In addition, for the assessment of polycyclic aromatic hydrocarbons (PAHs) an alternative approach has been suggested. The ecotoxicological threshold values represent ecologically acceptable concentrations for the aquatic environment. They are based on studies of freshwater organisms in surface water, as comparable methods for the groundwater habitat are lacking. The insignificance threshold values are not adequate for use as remediation goal values in cases of soil damage and should be defined on a case-by-case basis. Analysis of the damage caused so far showed it was not possible to derive threshold concentration levels for soil damage which, when exceeded, led to a sustainable change in the biological community. Thus no generally valid quantity magnitudes can be formulated to indicate a need for damage restoration. This should also be done on a case-by-case basis with regard to the ecotoxicological threshold values.