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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Testing is not scientifically justified as this substance is hydrolytically unstable and the decomposition products possess low aquatic toxicity. The read-across result of the 16-h toxicity threshold of 2-ethylhexanol to Pseudomonas putida (cell multiplication); 110 mg/l, based on the nominal concentrations, is used as key value in CSA. 

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
110 mg/L

Additional information

As the target substance hydrolyses immediately (half-life < 10 minutes) the toxicity to microorganisms is related to this main organic degradation product (2 -ethylhexanol) of the target substance.

The activated sludge respiration study was considered unnecessary for the unstable target substance as the main organic degradation product (2-ethylhexanol) is found to be readily biodegradable. In MITI-test, 2-ethylhexanol was not found to have any inhibitory effetcs to activated sludge at the test concentration of 100 ppm.

Since the target substance is highly water reactive, use of water is avoided in the use applications, there is no emission to a sewage treatment plant. Discharge to STP is relevant only in one use application when the target substance is used as a catalyst in industrial esterification processes. In this use application, water is used to remove the catalyst from the process. The discharge to WWTP is related to the degradation products of this substance as the hydrolysis will take place, and 2-ethylhexanol and TiO2 are released to WWTP. In addition, the concentrations of these degradation products in effluents are expected to be lower than the test concentration in MITI-test (100 ppm).

According to the ECHA Guidance on information requirements and chemical safety assessment, in absence of activated respiration test, toxicity results to microbial bacteria can be used for evaluate the inhibitory effects of chemicals to STP micro-organisms. Therefore, the result of the P.putida cell multiplication inhibition test of the organic hydrolysing product is used to calculate the PNEC STP.