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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

With high probability acutely not harmful to algae

Key value for chemical safety assessment

EC50 for freshwater algae:
330.5 mg/L

Additional information

One toxicity test on freshwater algae is available. This test carried out according to EU Directive 79/831/EWG. The 72 hour EC50 value for the growth rate with Scenedesmus subspicatus is > 100 mg/L, the EC10 and the NOEC based on growth rate are 14.892 mg/L and 1.560 mg/L, respectively [BASF AG, 1991].

The study design and the lack of analytical verification of exposure concentrations limit the adequacy of the study to address the acute toxicity of the substance, which has potential to evaporate from the test system due to its physical-chemical properties

However, based on its chemical structure, 1,3-dioxepane is expected to exert acute aquatic toxicity through a narcotic mode of action (narcosis or baseline toxicity) and therefore the endpoint can be adequately estimated from its structure. Estimations of short-term toxicity to growth rate of green algae conducted with two valid QSAR methods confirm the very low toxicity of 1,3 -dioxepane and support the result of the available experimental study.

A EC 50 of 330.5 mg/L (lowest effects concentration predicted by OECD Toolbox 4.1 and ECOSAR 1.11) is taken for chemical safety assessment

In conclusion, taking together the available experimental data and the QSAR predictions and using a weight-of-evidence approach, a EC50 of > 100 mg/l can be estimated for green algae.