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Toxicity to aquatic algae and cyanobacteria

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Description of key information

A toxicity study to aquatic algae and cyanobacteria with cesium sulphate is not available. Consequently, read-across was applied using data from cesium hydroxide monohydrate. Under the conditions of this acute algal growth inhibition test on Pseudokirchneriella subcapitata the observed endpoints for the effect of cesium hydroxide monohydrate based on the growth rate were the following: 72h EC50 value: 133.99 mg test item/L; 72h NOEC value: 12.5 mg test item/L and 72h LOEC value: 25 mg test item/L.
Based on these data the 72h-EC50 calculated for cesium was 106.1 mg/L., the 72h-LOEC was 19.8 mg/L and the 72h NOEC was 9.9 mg/L and for cesium sulphate the calculated 72h-EC50 value was 144.4, the 72h-LOEC was 26.9 mg/L and the 72h NOEC was 13.5 mg/L. All reported biological results are related to the nominal concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:
144.4 mg/L
EC10 or NOEC for freshwater algae:
13.5 mg/L

Additional information

A toxicity study to aquatic algae and cyanobacteria with cesium sulphate is not available. Consequently, read-across was applied using data from cesium hydroxide monohydrate.

An Acute Growth Inhibition Test of cesium hydroxide monohydrate on Algae (Pseudokirchneriella subcapitata) over an exposure period of 72 hours in a static system was assessed according to OECD Guideline 201 and EU method C.3. Five different concentrations arranged in a geometric series and an untreated control group were tested in the main study. The highest concentration was 100 mg/L. The following concentrations were used in the main study: 6.25; 12.5; 25, 50 and 100 mg/L. The shape of the algal cells growing was obviously not affected. Under the conditions of this acute algal growth inhibition test on Pseudokirchneriella subcapitata the observed endpoints for the effect of cesium hydroxide monohydrate based on the growth rate were the followings: 72h EC50 value: 133.99 mg test item/L; 72h NOEC value: 12.5 mg test item/L and 72h LOEC value: 25 mg test item/L.

Based on these data the 72h-EC50 calculated for cesium was 106.1 mg/L., the 72h-LOEC was 19.8 mg/L and the 72h NOEC was 9.9 mg/L and for cesium sulphate the calculated 72h-EC50 value was 144.4 mg/L, the 72h-LOEC was 26.9 mg/L and the 72h NOEC was 13.5 mg/L.