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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

Under the conditions of this acute daphnia toxicity study the observed endpoints for the effect of cesium hydroxide monohydrate were the followings: 48h NOEC value: 25 mg test item/L; 48h LOEC value: > 50 mg test item/L and 48h EC50 value: 94.44 mg test item/L. All reported biological results are related to the nominal concentrations. 
Based on these data, the calculated 48h-EC50 for cesium hydroxide anhydrous was 84.3 mg/L, the 48h-LOEC was greater than 44.6 mg/L and the 48h-NOEC was 22.3 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
94.44 mg/L

Additional information

An Acute Toxicity Test on Daphnia magna over an exposure period of 48 hours in a static system was assessed according to OECD Guideline 202 and EU method C.2. Five different concentrations of cesium hydroxide monohydrate arranged in a geometric series and an untreated control group was tested in the main experiment. The concentrations were in nominal: 6.25; 12.5; 25, 50 and 100 mg/L. The highest concentration tested without toxic effects after the exposure period of 48 hours, the 48h-NOEC and the 48h-EC0 of cesium hydroxid monohydrat to Daphnia magna was determined to be 25 mg/L. 5 % mortality was observed at the concentrations of 6.25 and 12.5 mg/L and in the control group, however this mortality was within the assay acceptance range; therefore the observed mortality was not evaluated as an effect. Immobilisation observed at 100 mg/L test item concentration was significantly different from the control (Dunnett’s Test). The 48h-LOEC was greater than 50 mg/L, while the 48h-EC50 was calculated to be 94.44 mg/L. All reported biological results are related to the nominal concentrations.

Based on these data, the calculated 48h-EC50 for cesium hydroxide anhydrous was 84.3 mg/L, the 48h-LOEC was greater than 44.6 mg/L and the 48h-NOEC was 22.3 mg/L.