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Short-term toxicity to aquatic invertebrates

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Description of key information

In this 48-hour acute toxicity test with Daphnia magna with cesium sulphate the 48 h EC50 value was determined as 91.2 mg/L, and the 48 h NOEC was determined to be 76.9 mg/L. The results are based on the nominal test item concentrations.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
91.2 mg/L

Additional information

The purpose of this study was to evaluate the influence of the test item cesium sulphate on the mobility respectively survival of Daphnia magna. Young Daphnia were exposed in an immobilisation test to aqueous test media containing the test item for 48 hours at a range of concentration under static conditions.

Based upon the results from the preliminary experiments, nominal concentrations of 35.0; 45.5; 59.2; 76.9 and 100.0 mg/L were investigated in the main study.

The test item concentrations remained within ± 20 % of the nominal during the test period of 48 hours; therefore all biological results are based on the nominal concentrations.

The quantification of the test item was performed by a previously validated analytical method. Samples were taken from each testing concentration and the control at the start and at the end of the study and analysed by flame photometer. The measured concentrations of cesium sulphate varied between 102 and 108 % of the nominal concentration during the experiment.

The 48-h EC50 value of the test item and their confidence limits were calculated using Probit analysis by SPSS PC+ software.

For determination of NOEC and LOEC, statistical analysis on immobilization was assessed by analysis of variance (ANOVA) and Bonferroni t-Test (α = 0.05) by TOXSTAT software. The 24-h EC50 and the 48-h EC100 was determined directly from the raw data.

In this 48-hour acute toxicity test with Daphnia magna the 48 h EC50 value was determined as 91.2 mg/L, and the 48 h NOEC was determined to be 76.9 mg/L. The results are based on the nominal test item concentrations.