Comparison of different life-cycle impact assessment methods for aquatic ecotoxicity

Human and ecotoxicity impact categories are problematic to quantify within life-cycle impact assessment (LCIA) because their local scope makes them di fficult to aggregate with the traditional global-impact categories used in life-cycle assessment (LCA). For being able to assess local impacts such as toxicity, LCIA developers increasingly include fate modeling into LCA. Thi s article follows this development by comparing different LCIA methods for aquatic ecotoxicology and by investigating the importance of fate within LC IA, the necessity of considering freshwater and seawater compartments separ ately, and the key degradation and intermedia transfer processes involved. The methods are compared by assessing an example study of domestic clothes washing in former West Germany. Four LCIA methods are selected and applied to four substances emitted during the washing process. The conclusion is th at the consideration of environmental fate does matter and that aquatic eco toxic impacts can differ significantly for the same substance in freshwater and in marine ecosystems. The way (bio) degradation, photolysis, volatiliz ation, and transfer from agricultural soils are considered plays an importa nt role as do the system boundaries chosen. This means that the LCIA method ology should remain flexible so that appropriate methods can be chosen for different applications. Fate models being developed in the environmental ri sk assessment of chemicals can contribute to the further improvement of LCI A methods.