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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Toxicity to microorganisms (3h, activated sludge of a predominantly domestic sewage) OECD 209, NOEC > 100 mg/L

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
100 mg/L

Additional information

The inhibitory concentration of dicyclohexylphthalate on the respiration of aerobic waste water bacteria was determined in a mixed population of activated sludge of a predominantly domestic sewage. The test method followed the OECD Guidelines for Testing of Chemicals No. 209.

The test item was directly weight into the test vessels. The respiration rates of the activated sludge treated with the test item at a concentrations of 100 mg/L differed by 8.4% from control. The respiration rate of the activated sludge to Dicyclohexylphthalate at the rate of 100 mg/L was not statistically significant reduced when compared to the control (Student ttest for homogenous variances with Bonferroni-Holm Adjustment, α=0.05).

The NOEC is established above 100 mg/L.

The positive control 3,5-Dichlorophenol was tested in the same way as the test item. The 3-hour EC50 was found to be 4.7 mg/L thus laying in the range of 2 - 25 mg/L recommended by the test guidelines. The result confirms the suitability of the activated sludge used.