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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

EC50 (total, heterotrophic and nitrification respiration) > 1000 mg/L (nominal) for activated sludge (OECD 209)

NOEC (total, heterotrophic and nitrification respiration) ≥ 1000 mg/L (nominal) for activated sludge (OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

One key study is available for 2-{2-chloro-4-mesyl-3-[(tetrahydrofuran-2-ylmethoxy)methyl]benzoyl}cyclohexane-1,3-dione, in which the toxicity to microorganisms was investigated. The study (M-570517-01-1; 2016) was conducted according to GLP and OECD guideline 209. The activated sludge was exposed to the test item at five test item concentrations of 10, 32, 100, 320 and 1000 mg/L for 3 h. Test concentrations are given as nominal concentrations. The respiration rate (oxygen consumption) is classified into two processes of oxidation, the oxidation of organic carbon (heterotrophic oxidation) and the ammonium oxidation (nitrification). By measuring the oxygen consumption rates in the presence and absence of a specific inhibitor of nitrification ATU (N-allylthiourea), total, heterotrophic and nitrification respiration rates were calculated. Nitrification inhibition could not be calculated as the differences between total and heterotrophic respiration rates were too small. As no inhibition was observed for total and heterotrophic respiration up to the highest tested concentration of 1000 mg/L, the same effect values for nitrification were chosen. No effect was detected up to a test item concentration of 1000 mg/L. Therefore, the EC50s and NOECs for total respiration, heterotrophic respiration, and nitrification respiration were determined as >1000 mg/L and ≥1000 mg/L, respectively.