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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

EC50(3h)= 249 mg/L, Activated sludge, OECD 209, Eisner 2015

Key value for chemical safety assessment

EC50 for microorganisms:
249 mg/L
EC10 or NOEC for microorganisms:
3.4 mg/L

Additional information

Several studies have been conducted in order to asses the toxicity potential of the test item towards various microorganisms: V. fisheri (Aruoja 2011), P. putida (Knie 1983), S. cerevisiae (Liao 1996) and P. phosphoreum (Huang 1996 and Ribo 1984). However, the data are of limited relevance to STP microorganism toxicity.

A GLP compliant study carried out in accordance with recent guidelines by Eisner (2015), measured the inhibitory effect of the test material on the respiration rate of aerobic activated sludge microorganisms of domestic sewage at 20 °C in static fresh water, when exposed to the test item for 3 hours. The specific respiration rate of the blank controls was higher than 20 mg O2/gh, the coefficient of variation of oxygen uptake rate in control replicates was less than 30 % and the 3-hour EC50 of 3, 5-dichlorophenol is within the range of 2-25 mg/L, therefore the validity criteria were fulfilled. The 3-hour EC50 values was determined to be 249 mg/L. The value is selected to be carried forward for risk assessment, classification and labelling. The study is considered complete, adequate and reliable for the purpose of risk assessment and classification.