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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Exposure of Scenedesmus subspicatus to the test material, based on nominal test concentrations, gave an EbC50 (72h) value of 0.25 mg/L; 95% confidence limits 0.21 - 3.0 mg/L and an ErC50 (0 -72h) value of 1.2 mg/L (It was not possible to calculate 95% confidence limits for the ErC50 value as the data generated did not fit the models available for calculation of confidence limits.) The NOEC (72h) was 0.048 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
1.2 mg/L

Additional information

In a key study performed to OECD Guideline No 201 and EC Method C3, following a preliminary range-finding test, Scenedesmus subspicatus was exposed to solutions of the test material at nominal concentrations of 0.048, 0.095, 0.19, 0.38, 0.75 and 1.5 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24±1°C. The test material solutions were prepared by shaking an excess (100 mg/L) of test material in culture medium at 300 rpm at a temperature of 30°C for 24 hours prior to removal of any undissolved test material by filtration (0.2µm) through a preconditioned filter to produce a saturated solution with a nominal test concentration of 30 mg/L. This "saturated" solution was then further diluted, as necessary, to provide the remaining test groups. The nominal test concentrations were based on the results of chemical analysis of a saturated solution prepared during the range-finding test where the measured concentration of the saturated solution was 31.7 mg/L.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter Multisizer Particle Counter.

Exposure of Scenedesmus subspicatus to the test material, based on nominal test concentrations, gave an EbC50 (72h) value of 0.25 mg/L; 95% confidence limits 0.21 - 3.0 mg/L and an ErC50 (0 -72h) value of 1.2 mg/L (It was not possible to calculate 95% confidence limits for the ErC50 value as the data generated did not fit the models available for calculation of confidence limits.) The NOEC (72h) was 0.048 mg/L.