Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Studies on three trophic levels are available with the lowest EC50 found in algae (33.1 mg/L). In this study the concentrations decreased significantly over the exposure period of 72 hours. The LC50 for fish is 44.6 mg/L and for daphnia an EC50 of > 100 mg/L was derived.

The EC10 from the algae study is 3.4 mg/L, which is much lower than the NOEC for fish (120 mg/L in a 28 day study) and daphnia (25 mg/L in 21 day reproduction test).

No explanation for the rapid decrease of concentrations in the algae study was provided.

In most studies available the pH of the test medium was adjusted to neutral or slightly basic level. In a study by Lee (2009) the test substance's effects on growth of algae were tested at unadjusted pH and at pH 6.5, 7 and 7.5 . The effect was a clear shift in the dose response curve favouring conditions of higher pH (less impact on growth rates). It is expected that the aquatic toxicity of the test substance under environmental relevant conditions is correctly represented by the test conditions used in the available toxicity studies.

The reported NOEC for this study based upon time weighted average (TWA) concentrations do not accurately represent the intrinsic toxicity of the substance, which due to the issues with the lack of analytical detection of the test substance, the TWA concentrations that must be used resulted in a huge spacing factor between the LOEC and NOEC. EC10 better represent the potential toxicity of the substance as these are conservative estimates that biologically significant adverse effects are being demonstrated in the test.