ecotoxicology

Estrogenic effect of wastewater from different sources on recombinant yeast cells: Dark test tubes: estrogenic effect, Light test tubes: no estrogenic effect. Photo: Schweigert, EAWAG.

With the establishment of a comprehensive system of works for the treatment of domestic, industrial and commercial wastewater, levels of chemical pollution in many of Switzerland's watercourses have been substantially reduced in recent decades. However, a wide range of chemicals - generally in low to very low concentrations - still enter our waters from various sources, such as treated effluent discharges or rainwater/agricultural run-off. In many cases, detection of these substances by chemical analysis is not possible or requires complex methods. In addition, the effects of mixtures of chemicals in very low concentrations in waterbodies are largely unknown. Substances with similar actions may have additive effects, mutual inhibition may occur, or the effects may be synergistic. The question of how these chemical "cocktails" affect our freshwater ecosystems may be examined by using ecotoxicological methods, i.e. investigating the effects of water samples on cells or organisms.

In the Ecotoxicology module, the potential toxicity of water samples is to be investigated in a two-step procedure. The first step involves screening for potential toxicity using batteries of cell test systems. The effects investigated include direct cellular toxicity, inhibition of photosynthesis, damage to DNA, reproductive toxicity, and estrogenic and other hormonal (non-estrogenic) effects. Only if toxic effects are detected at the cellular level does the investigation proceed to the second step, where tests are carried out to establish whether toxic effects also occur in selected organisms.

The Ecotoxicology module is currently being developed by EAWAG.

Recommended procedure in the Ecotoxicology module

Download of the draft concept of the Ecotoxicology module (Proposed procedure, November 2001, in German only)
Further information about the Ecotoxicology module: Schweigert et al. (2002) How can the degree of pollutant impact on a stream be documented? EAWAGnews 51e, 10-12.