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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

EC50(72h) > 100 mg/L (nominal), EC50 > 56 mg/L (measured) - for growth
NOEC(72h) = 100 mg/L (nominal), NOEC = 56 mg/L (measured) - for growth

Key value for chemical safety assessment

Additional information

The toxicity of Vinasses, residue of fermentation towards aquatic algae was investigated in a study conducted according to the OECD Guideline 201 “Alga, Growth Inhibition Test” (Bouwman, 2010). The freshwater algae Pseudokirchneriella subcapitata was used as test organism and exposed to a nominal concentration of 100 mg/L for 72 h. Based on the TOC content of the test material (i.e. 25.96%) the concentration of Vinasses in the aquatic samples was calculated and corrected for the control. No acute effects were observed based on growth rate and yield (EC50(72h) > 56 mg/L, measured, EC50(72 h): > 100 mg/L, nominal). Furthermore, under the conditions of the present study Vinasses did not induce growth rate reduction at a nominal concentration of 100 mg/l (NOEC), corresponding to an average exposure concentration of 56 mg/L. However, the test substance induced 23% inhibition of yield at a loading rate of 100 mg/L, i.e. the NOEC was below a loading rate of 100 mg/L corresponding to an average exposure concentration of 56 mg/L (for yield).

 

Similar to observations in the acute fish test on this substance, after two days of exposure onwards the limit concentration was observed to contain undissolved particles. There is no test on the water solubility of this test substance available, but 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 of 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 precipitation.