Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Fish (acute): In the key study (Geiger, 1985) with Pimephales promelas the LC50 (96 h) was 484 mg/L based on measured concentrations under flow through conditions.

Fish (long-term): A long term study with Danio rerio in freshwater (Tsay, 2007) was available which was key study. This study showed that the NOEC is 10 mg/L.

Daphnia (acute): In the key study (Ewell, 1986) with daphnia magna the LC50 (96 h) was >100 mg/L based on nominal concentrations.

Daphnia (long-term): A long term study is waived based upon REACH Annex IX Section 9.1 column 2 on grounds that there is no need to further investigate the effects on aquatic organisms.

Algae: In the key study (Migchielsen, 2010) with Pseudokirchnerella subcapitata the EC50 (72 h) was >30.5 mg/L, EC10 (72h) was 6.5 mg/L and NOEC (72h) was 0.09 mg/L, based on measured concentrations.

Micro-organisms: In the key study with Achromobacter sp. (Nikkilä, 1955) the NOEC (168h) was >100 mg/L.

The algae study is based on measured concentrations and will be taken as starting point for the calculations of the PNECs for the aquatic compartment. The LC50 for fish is based upon measured concentrations and EC50 for daphnia is based on nominal concentrations. Based on the presence of a supporting static study in fish which showed a nominal LC50 of >100 mg/L (Ewell, 1986), it is expected that the concentrations in the key studies with fish and daphnia represent actual concentrations to sufficient extent. This allows the conclusion that the EC50 and EC10 of the algae study represent the worst case levels.

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.