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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The toxicity of cyclohexylamine to activated sludge was investigated according to ISO 8192 (Test for Inhibition of Oxygen Consumption by Activated Sludge) yielding an EC50(3 h) of 2251 mg/L and an EC10(3 h) of 326 mg/L (Bayer AG, 1990).

Key value for chemical safety assessment

EC50 for microorganisms:
2 251 mg/L
EC10 or NOEC for microorganisms:
326 mg/L

Additional information

According to the Guidance document R.7b (ECHA, 2008), preference is given to tests with a mixed inoculum that assess the functioning of the entire microbial community in a sewage treatment plant, rather than tests based on single species or even microbial sub-systems. Respirometry is generally considered as an approach that will integrate the functioning of all organisms in an STP. Concluding, Bayer AG (1990) was chosen to represent the toxicity of the test item towards microorganisms and thus the functioning of the sewage treatment plant, as all studies performed by Bringmann used single species as test organisms. These species represent only a minor part of microorganisms present in sewage treatment systems and should only be used for the risk assessment in the absence of other reliable data.