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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The toxicity of the substance to algae was determined in a study in accordance with OECD TG 201. In this study, the NOErC was determined at 115 mg/L (measured concentration) and the EC50 is determined at >215 mg/L.  

Key value for chemical safety assessment

EC50 for freshwater algae:
215 mg/L
EC10 or NOEC for freshwater algae:
115 mg/L

Additional information

The toxicity of the substance to algae was determined in a study in accordance with OECD TG 201 and in compliance with GLP criteria (Brixham Envriomental laboratory, 2009). In this study, freshwater algae (Pseudokirchneriella subcapitata) were exposed to nominal concentrations of 0, 4.38, 8.75, 17.5, 35 and 70% of saturation for 72 hours under static conditions. Nominal concentrations were prepared by bubbling test substance through 3500 mL of sterile media for approximately 60 minutes to obtain a saturated solution of the gas (100 %). This was diluted to 70 % saturation with sterile oxygenated media; this stock was used for the top concentration. All other concentrations were prepared from this stock, and inverted in volumetric flasks to mix. Test concentrations were analytically verified. Mean measured concentrations were 13.5, 32.0, 60.5, 115, and 215 mg/L. After 72 hours exposure, a significant difference in yield was found at 32.0 mg/L and three significant differences in growth rate were found at 13.5, 32.0 and 60.5 mg/L. These effects were however considered due to the hormetic effect rather than an inhibitory effect, and were thus discounted. Only at the highest tested concentration of 215 mg/L was a significant harmful effect on growth rate observed (37% inhibition compared to control). Based on these findings, the NOErC was determined at 115 mg/L (measured concentration). The ErC50 (for growth rate) could not be calculated as inhibition remained below 50%. For purpose of assessment, the EC50 is determined at >215 mg/L and therewith at 215 mg/L.