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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

In a guideline, 96-hour algal growth inhibition test with Pseudokirchneriella subcapitata, the test material exhibited 96-hour EC50 values of 1.4, >1.5 and > 1.5 mg/L based on biomass (AUC), growth rate and yield, respectively.  The 96-hour NOEC was 0.12 mg/L for biomass and 0.67 mg/L for growth rate and yield. The 96-hour LOEC was 0.27 mg/L for biomass and 1.5 mg/L for growth rate and yield.  The results are based on the mean measured test item concentration calculated as the geometric means of the concentrations measured at the start and end of the test.

Key value for chemical safety assessment

EC50 for freshwater algae:
1.5 mg/L
EC10 or NOEC for freshwater algae:
0.67 mg/L

Additional information

The toxicity of the test material to the green algae Pseudokirchneriella subcapitata was tested in an GLP compliant, guideline study. The algae were exposed for up to 96 hours to 5 concentrations of the test substance. As the test substance has low solubility in the test media a dispersion was formed by mixing the test substance in the test media for a prolonged period of time. After filtration this stock solution was used undiluted as the maximum exposure concentration and as a series of dilutions to form the other test concentrations. Analytical monitoring of the exposure concentrations was undertaken and the results are expressed as the geometric mean measured concentration from the start and end of the exposure period. The 96-hour EC50 are 1.4, >1.5 and > 1.5 mg/L based on biomass, growth rate and yield, respectively. The 96-hour NOEC was 0.12 mg/L for biomass and 0.67 mg/L for growth rate and yield.

The study is considered reliable and relevant for risk assessment. As no 96h EC50 could be determined for the growth rate the result was not considered adequate for classification and labeling purposes.