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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

EC50 (aquatic algae; growth rate)= > 88 mg/L, 72 hour, freshwater, OECD 201, Migchielsen 2013
EC10 (aquatic algae; growth rate)= 19 mg/L (C.I. 11-32 mg/L), 72 hour, freshwater, OECD 201, Migchielsen 2013
NOEC (aquatic algae; growth rate)= 7.1 mg/L, 72 hour, freshwater, OECD 201, Migchielsen 2013

Key value for chemical safety assessment

EC50 for freshwater algae:
88 mg/L
EC10 or NOEC for freshwater algae:
7.1 mg/L

Additional information

The algal growth inhibition to Pseudokirchneriella subcapitata, was carried out according to OECD 201 Freshwater Alga and Cyanobacteria, Growth Inhibition Test and EU Method C.3 guidelines. A final test was performed based on the results of a preceding combined limit/range-finding test. Six replicates of exponentially growing algal cultures were exposed to untreated control medium, while three replicates per group were exposed to nominal concentrations of 10, 20, 40, 80 and 160 mg/l. The total test period was 72 hours and the initial algal cell density was 104 cells/ml. Samples for analytical confirmation of actual exposure concentrations were taken at the start, after 24 and 72 hours of exposure. At the start of the test, the actual test concentrations approximated 80% relative to the nominal concentrations. After 24 hours of exposure concentrations had generally decreased by 20-30% below initial and after 72 hours concentrations had even further decreased. Based on these results, the average exposure concentrations were calculated to correspond with 3.1, 7.1, 16, 36 and 88 mg/l based on Time Weighted Average (TWA). The study met the acceptability criteria prescribed by the guideline. The 72h-NOEC for growth rate reduction based on TWA concentrations was 7.1 mg/l. The EC50 for growth rate reduction (72h-ERC50) based on TWA concentrations was > 88 mg/l.