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Short-term toxicity to aquatic invertebrates

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Description of key information

EC50 (48h) > 100 mg/l (nominal)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
100 mg/L

Additional information

The toxicity of test material to daphnids was evaluated according to the OECD Guideline 202. Twenty daphnids, divided in groups of five, were exposed to different concentrations of the substance ranging from 2200 and 10000 mg/l. After 24 h in darkness, the immobilization of the daphnids was measured. The daphnids that were unable to swim for 15 s after gentle stirring were considered immobile; EC50 (24h) = 6234 ± 466 mg/l (nominal)


 


A second study is performed according to the OECD 202 and EU Method C.2 and under GLP conditions. This study is performed as a limit test in order to evaluate the toxicity of the test item in an acute immobilisation test under static conditions towards Daphnia magna. Daphnia magna Straus was chosen in the guideline as a typical species of zoo-plankton. Young daphnia, aged less than 24 hours at the start of the test, are exposed to the test item for a period of 48 hours. Immobilisation is recorded at 24 hours and 48 hours and compared with control values. Not more than 10 % of the control daphnia should show immobilisation or other signs of disease or stress, for example, discoloration or unusual behaviour such as trapping at surface of water. The results are analysed in order to determine the EC50at 48 h is determined. 


A positive control was tested in a separate study to assure that the test conditions are reliable.


The limit test was chosen based on the results of the range finding test. Ten daphnids per concentration were exposed to 0 -1 -10 -100 mg/l and the immobilisation was observed at 24 and 48 hours. One daphnid was found immobilised at the highest tested concentration at 24 hours and at 48 hours. No daphnids were immobilised in the rest of the tested concentrations.


Therefore, for the main study only one concentration at 100 mg/l was chosen. For the test concentration and the blank control, 20 daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted.
At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC.
The measured concentration was 93 % of the nominal concentrations at the beginning of the test and 104 % of the nominal concentrations at the end of the test. Therefore, the determination of the biological results was based on the nominal concentration.


None of the animals was immobilised in the blank control and the tested concentration.


The EC50 at 48 h (nominal) is therefore > 100 mg/l. 

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