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Short-term toxicity to fish

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Description of key information

LC50(96h) > 100 mg/L (nominal); > 58 mg/L (measured)

Key value for chemical safety assessment

Additional information

The short-term toxicity of Vinasses, residue of fermentation towards fish was tested according to the OECD Guideline 203 “Fish, Acute Toxicity Test” (Bouwman, 2010). Cyprinus carpio was used for testing in a static limit test (loading 100 mg/L, nominal). After a test duration of 96 h, no mortality or other abnormal responses were observed. Based on the TOC content of Vinasses (i.e. 25.96%) the concentration of Vinasses in the aquatic samples was calculated and corrected for the control. Thus, the test resulted in an LC50 (96 h) of > 58 mg/L based on the average exposure concentration.

During the test, dissolved oxygen concentration had dropped to 3.1 mg/L in the limit concentration (after 2 days of exposure). Therefore, aeration was introduced immediately. No fish mortality or any other clinical effects were observed. Furthermore, after two days of exposure the limit concentration was observed to be hazy. The following days undissolved test substance was seen in the test vessel. The study author concluded that the applied concentration was above the limit of water solubility of Vinasses, residue of fermentation. There is no test on water solubility of this test substance available. Whereas, for the similar UVCB substance, Vinasses, residue of fermentation containing biomass of Corynebacterium glutamicum, it was shown that a large fraction of components with relatively high water solubility is existent (Oudhoff 2010, OECD 105). However, the test substance was not completely soluble in water since in all samples undissolved test substance particles were observed. Nevertheless, large fractions exhibited a very high water solubility (38g/L at a loading rate if 100g/L, pH 3.5-3.6). Therefore, it can be concluded, that the observed hazyness and partly precipitations are rather a result of the variable composition of this test substance, than of a limited water solubility. It is likely that both bacterial activities together with the variable composition of the substance resulted in the observed oxygen depletion and precipitation.