Environmental footprinting with USEtox® goes metal!
Conscious of the specificity of metals and the need to take into account bioavailability to avoid overestimation, an update of the characterization factors (CF) available in the ecotoxicological footprinting database using the USEtox® model was performed.
Metals behave diffently
Many pollutants are found in the environment with several physicochemical properties which provide different behaviours. Metals behaviour differs from organic compounds: they are infinitely persistent, octanol-water partition doesn’t predict their tendency to bioaccumulate and only the truly dissolved fraction is considered to be bioavailable. For these reasons, physicochemical properties to take into account for metals in the USEtox® model differ from organic compounds.
Representative European freshwater river
Dong et al. (2014) publication provided CF for 15 cationic metals. The Kpss and the KDOC were calculated with the WHAM 7.0 model which takes into account the equilibrium-based metal speciation model, for a specific water chemistry. Physicochemical parameters and Effect factors (EF) from Dong et al. were implemented preferentially. If not available, the EF came from the AiiDA database. The physicochemical parameters came from the USEtox® inorganic database, if not from Echachem, and if not from Echachem, they were finally estimated by calculation. The landscape was changed to approach a representative European freshwater river and physicochemical parameters were selected for this same river.
Updates relate to the 15 cations from the Dong et al. publication and the 7 cations from the USEtox® inorganic database. Changing Kpss and KDOC found by Dong et al. in the ecotoxicological footprinting database allows to find the same bioavailability factor (BF). This shows that other physicochemical parameters implemented before this work don’t have a significant impact on this factor. The new CF for the freshwater range from 9.6E0 (Fe III) to 1.1E6 (Cd II). From now on, the ecotoxicological footprinting with the USEtox® model database takes into account the bioavailability of the metals in the CF calculation. This is now available in the online database for 22 cations. Up to now, BF existed in recent publications but had not yet been implemented in models to calculate CF.
More information on the environmental footprinting with USEtox®
The USEtox® model was developed under the UNEP-SETAC Life Cycle Initiative, by a team of researchers, and provides the state-of-the-art for the ecotoxicological impact assessment of substances. To access the USEtox® footprinting platform, please click here. Please note that you can set up a free account and test the platform (click on Free access, create an account).
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Image credit: Carol Stoker