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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

A study was performed to assess the effect of the test material on the growth of the green algae Pseudokirchneriella subcapitata, strain: NIVA CHL 1.The method followed that described in the OECD TG No 201. Following a preliminary range-finding test, the algae were exposed to a Saturated Solution (SS) prepared at a loading rate of 100 mg/L and 4 dilutions of this SS (three replicate flasks per concentration) and a control (six replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature between 22 and 23°C. Preparation of test solutionsstarted with a loading rate of 100 mg/L applying one day of magnetic stirring in a closed vessel in order to reach the maximum solubility of the test item in the test medium. The resulting aqueous mixture was left to stabilize for one hour whereafter the clear and colourless Saturated Solution was siphoned out and used as highest test solution. The lower test concentrations were prepared by subsequent dilutions of the SS in test medium.Samples were taken from all treatments at t = 0 , 24, 48 and 72 h and analysed with a validated GC-FID method.All concentrations decreased during the test period. After 72 hours of exposure, the three lowest test concentration were below the LOQ, while the highest two concentrations were 0.16 and 0.53% of initial, respectively.Therefore the geometric mean measured concentrations were calculated and used for expression of endpoints. Statistically significant inhibition of growth rate was found at the three highest geometric mean measured concentration, starting at 0.10 mg/L. However, the effects at 0.10 and 0.23 mg/L, respectively, were biologically not relevant (<10%). Therefore the NOErC was set at 0.23 mg/L. The ErC10 and ErC50 based on geometric mean measured concentrations were 0.37 and >0.66 mg/L, respectively.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
0.37 mg/L

Additional information

EC50 growth rate is > 0.66 mg/l