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Toxicity to microorganisms

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Description of key information

Available information:
The respiration rate of an activated sludge exposed to 1,1-DPE and fed with a standard amount of synthetic sewage feed was measured.. The inhibitory effect of the test substance was expressed as a percentage of the mean respiration rates of two controls. For a respiration inhibition test to be considered valid, the control values should be within 30% of each other. An EC50 obtained for the reference material must be within 2-25 mg/L. The control coefficient variation was 24% and an EC50 value of 9.19 mgIL was determined for the reference substance, rendering the test valid. For test substance 1-Phenylethylbenzene, an EC50 of> 1 000 mg/L was obtained at 3 hours post dose. Results presented are based on nominal concentrations.
The influence of Phenyl-tolyl-ethane on the respiration rate of activated sludge was investigated after a contact time of 3 hours according to OECD guideline 209. The EC50 was above the highest loading rate tested (1000 mg/l).

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

From the available data for toxicity to microorganism it can be concluded that 1,1’-DPE is devoid of any relevant toxicity to microorganisms.

This is confirmed by data from the read-across substance PTE which also demonstrates no relevant toxicity to microorganism (EC50 > 1000 mg/l).

The key study is GLP-compliant and has a Klimisch score of 1 (1,1 -DPE). The key study is used for chemical safety assessment. No further testing is required. For detailed read across rationale and justification see section 13, Read across document.