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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

EC50 (3h contact time) >10 mg/L (OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:
10 mg/L

Additional information

Phenol 2,4 -bis(1,1-dimethylethyl) was evaluated for its toxicity on a mixed population of activated sewage sludge microorganisms. EC50 value (3h contact time) for test substance was > 10 mg/l. The test substance is toxic to microorganisms.

Test method:

The method used followed that described in the OECD Guidelines for testing of Chemicals / Section 2: Effects on Biotic Systems, Test No. 209 "Activated Sludge, Respiration Inhibition Test". Deviations are in the number and values of concentrations (this is not expected to compromise the quality of the study results).3,5 -dichlorophenol was the reference substance at 3.2 and 32 mg/l. O2 consumption rates were measured after 3 h contact time at concentrations of 10, 100 and 1000 mg/l of test substance in the range finding study, and 10 mg/l for the 3 replicates in the definitive study. Variation between controls was ± 5% in the range finding study and ± 3% in the definitive study. EC50 value (3h contact time) for reference substance was 10 mg/l.