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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

In a GLP-study according to OECD test guideline 209, the registered substance did not reduce the respiration rate at a nominal concentration (WAF) of 100 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
100 mg/L

Additional information

For the registered substance, one microorganisms toxicity study was available. As this study was conducted under GLP-conditions according to an OECD test guideline it was considered as Klimisch 1.

The effect of the registered substance on the respiration rate of an activated sludge according to the OECD guideline 209 after an incubation duration of three hours was investigated. Due to the low water solubility of the test substance, a WAF (water accommodated fraction) was used for testing. As inoculum microorganisms from a sewage treatment plant mainly fed with municipal wastewater were used. The respiration rate of the activated sludge incubated with the WAF of the registereed substance was found to be 25.4 mg 02/(L*h) after three hours. Thus the respiration rate of the assay containing the substance was in the range of the control assays of 21.1 — 23.8 mg 02/(L*h). There was no inhibitory effect of the test item on the respiration rate. The EC50 of the reference item 3,5-dichlorophenol for respiration inhibition was between 5 and 17.5 mg/I. The validity criterions concerning the reference item and the comparability of the controls were fulfilled. No important oxygen consumption by the registered substance was detected after three hours. On the basis of this result, the registered substance in a nominal concentration of 100 mg/L causes no inhibition of the respiration rate of an activated sludge in a respiration inhibition test (BPCN, 2006)