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Long-term toxicity to aquatic invertebrates

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Description of key information

The NOEC for the reaction mass was derived from the most sensitive value for one single component of the mixture. In order to this, the NOEC for the reaction mass is > 0.953 mg/l.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
NOEC
Effect concentration:
0.953 mg/L

Additional information

To assess the chronic toxicity of cyclohexanol to aquatic invertebrates a GLP study according to OECD guideline 211 was conducted with daphnia magna. The test organisms were exposed to the nominal concentrations: 0, 0.1, 0.32, 1.0, 3.2 and 10 mg/L for 21 d in a semi static system. The time weighted mean measured concentrations were 0.0445, 0.0962, 0.224, 0.953 and 4.09 mg/L, equivalent to 45, 30, 22, 30 and 41% of nominal concentrations, respectively. Under the conditions of this study, the NOEC value for adult survival was considered to be 0.953 mg/L. The EC50 for adult survival was considered to be 1.775 mg/L. The NOEC value for juvenile production was considered to be 0.953 mg/L and the EC50 for juvenile production was considered to be greater than 0.953 mg/L. The NOEC value for growth was considered to be 0.953 mg/L and the EC50 for growth was considered to be greater than 0.953 mg/L. All values were based on time weighted mean measured concentrations.


No experimental studies are available to assess the long-term toxicity to aquatic invertebrates of cyclohexanone. Therefore, the toxicity was predicted by the scientifically valid QSAR software QSAR Toolbox v4.3.1; Database v4.3.1. The substance is within the applicability domain of the model. The predicted NOEC after 21 d was 26.6 mg/l.


The NOEC for cyclohexanol is more sensitive (0.953 mg/l) than the with QSAR predicted NOEC for cyclohexanone (26.6 mg/l) and it resulted from an experimental study. Therefore, the NOEC for the reaction mass can be derived from the NOEC of the single component. By choosing the most sensitive value of one component the worst-case scenario for the mixture is covered. In order to this, the NOEC for the reaction mass is 0.953 mg/l.

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