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Toxicity to microorganisms

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Description of key information

Key value for chemical safety assessment

EC50 for microorganisms:
666 mg/L

Additional information

In the study from Wolf (2001), the respiration inhibition of CTFEP (purity 91.4%) was determined under GLP according to the OECD 209 and the EU C.11. Deviating from these guidelines the test temperature was 23.2 °C instead of 20 +/- 2°C. This deviation is considered to have no adverse effects on the integrity of the study. The test was performed with sludge collected from a communal sewage treatment plant. The concentration of suspended material was 1.56 g/L. Nominal concentrations were: Control, 25.6, 64.0, 160, 400 and 1000 mg test item/L corresponding to 0 (control), 23.4, 58.5, 146, 366, and 914 mg CTFEP/L. The controls were set up in duplicate, the treated test solutions were set up with 1 replicate/treatment level. The exposure duration was 3 hours. The test solutions were aerated with 0.1 to 0.2 ml/min. After 3 hours the oxygen consumption was measured with an oxygen sensitive electrode. The inhibitory concentrations IC for 20 and 50% inhibition when compared to the control were calculated. The IC20 and IC50 were 74 and 729 mg test item/L corresponding to 67.6 and 666 mg CTFEP/L. A test with the reference item Dichlorophenol verified that the test system was suitable for testing.

The test was performed with technical product of CTFEP. The identity of the impurities was not reported. This study was performed according to international guidelines and under GLP. Therefore, this study was considered to be Klimisch 1 study.

The obtained results are considered as relevant for the risk assessment.