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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

A study acc. to OECD209 (2010) was performed to investigate the effects of Benzophenone on the respiration rate of activated sludge. The NOEC was set at 31.6 mg/L. The EC50 was determined to be at 787 mg/L. 

Key value for chemical safety assessment

EC50 for microorganisms:
787 mg/L
EC10 or NOEC for microorganisms:
31.6 mg/L

Additional information

In a GLP study acc. to OECD 209 (2010) the effect of Benzophenone on the respiration rate of activated sludge was performed. . Nominal test item concentrations were 10, 31.6, 100, 316 and 1000 mg/L, five repliactes were set up for each concentration.

The inhibition of respiration for the test item replicates ranged from -9 % to 55 % compared to the control. The NOEC was set at 31.6 mg/L. The EC50 was determined to be at 787 mg/L.

One of three validity criteria were not fulfilled. The mean oxygen uptake rate of the control replicates was below the validity criterion of ≥ 20 mg O2/g x h. The oxygen uptake of activated sludge from municipal treatment plants is influenced by seasonal fluctuations and fluctuations in sewage flow etc. The lower oxygen uptake rate reflects the range of common uptake rates of activated sludge from municipal treatment plants and was considered to have no impact on quality and integrity of the study. Despite the lower respiration, the EC50-value of the reference item was in the required range. Therefore the lower respiration can be considered to have no impact on the results of the test item. Although this validity criterion was not fulfilled the study is considered to reflect reliable effects of Benzophenone on the respiration of activated sludge.