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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Under the conditions of the performed Activated Sludge Respiration Inhibition Test, the EC10 and EC50 values of test item were determined as 12.8 mg/L (95% confidence limits: 10.5–15.6 mg/L) and 37.0 mg/L (95% confidence limits: 32.4–42.2 mg/L), respectively. Based on the statistical and biological evaluation in this test the NOEC was determined as 6.33 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
37 mg/L
EC10 or NOEC for microorganisms:
12.8 mg/L

Additional information

The influence of the test item Methyl-isobutyl-ketone-peroxide (MIKP) on the activity of the activated sludge was evaluated by measuring the respiration rate under defined conditions according to OECD guideline 209 and EU method C.11. The respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. Based on the preliminary information about the test item caused effect on the activated sludge inoculum, the test item Methyl-isobutyl-ketone-peroxide (MIKP) was investigated at the nominal concentrations of 2.67; 6.33; 16; 40 and 100 mg/L, without pH adjustment. Defined amounts of the test item (in a form of the corresponding volumes) were added directly into the test vessels.

Under the conditions of the performed Activated Sludge Respiration Inhibition Test, the EC50 value of test item was determined as 37.0 mg/L (95% confidence limits: 32.4–42.2 mg/L). Based on the statistical and biological evaluation in this test the NOEC was determined as 6.33 mg/L.