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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)= >1.8mg/L, 72 hour TWA, freshwater, OECD 201, Harlan Laboratories Ltd. 2013
EC10 (aquatic algae; growth rate)= 1.4 mg/L, 72 hour TWA, freshwater, OECD 201, Harlan Laboratories Ltd. 2013
NOEC (aquatic algae; growth rate)= 0.33 mg/L, 72 hour TWA, freshwater, OECD 201, Harlan Laboratories Ltd. 2013

Key value for chemical safety assessment

EC50 for freshwater algae:
1.8 mg/L
EC10 or NOEC for freshwater algae:
1.4 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. Following a preliminary range-finding test, P.subcapitata was exposed to solutions of the test item at nominal concentrations of 1.0, 3.2, 10, 32 and 100 % (v/v) saturated solution (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. Analysis of the test preparations at 0 hours showed measured concentrations to range from 0.0042 to 5.5 mg/L. Given that the test item was known to be unstable under test conditions, it was considered appropriate to provide samples for analysis at 24, 48 and 72 hours in order to better define the rate in decline in measured concentration. Analysis of the test preparations at 24 hours showed concentrations in the range of 0.0049 to 3.6 mg/L were obtained. At 48 hours concentrations in the range of less than the limit of quantification (LOQ), determined to be 0.0046 mg/L, to 0.042 mg/L were obtained whilst a further decline in measured concentration to less than the LOQ in all test samples was observed at 72 hours. Given this decline in measured test concentration, in accordance with Guideline requirements it was considered appropriate to calculate the results based on the time-weighted mean measured test concentrations only. The 72h-NOEC for growth rate reduction based on TWA concentrations was 0.33 mg/l. The 72h-EC50 for growth rate reduction (72h-ERC50) based on TWA concentrations was >1.8 mg/l. The study met the acceptability criteria prescribed by the guideline.