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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The validity criteria applied to this study type were met and therefore the study is considered valid.
The following endpoints are applied to the study data of an OECD 209 study on the test substance:
NOEC: 9.5 mg/L
LOEC: 9.5 mg/L
EC50: 157.6 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:
157.6 mg/L
EC10 or NOEC for microorganisms:
9.5 mg/L

Additional information

The objective of this study was to determine the no observable effect concentration (NOEC) and the effect concentration for a 50% effect (EC50) for activated sludge exposed to the test substance, where possible. The study was undertaken according to OECD Guideline 209, Adopted July, 2010.

A range-finding test was undertaken in order to establish suitable dose levels for the definitive test.

The definitive test rate concentrations were 9.5, 30.5, 97.7, 312.5 and 1000 mg/L and were achieved by direct addition of the test substance to the test vessels.

The activated sludge inoculum was collected from the sludge return line at Burley Menston Sewage Treatment Works (West Yorkshire, U.K.) which has a predominantly domestic catchment. The point of collection was to ensure that the activated sludge sample was relatively free of exogenous material.

For the definitive test the suspended solids concentration for the sludge was 3.872 g/L and was within the required range of 3 g/L ± 0.3 g/L and was adjusted to nominal range using de-chlorinated water. The pH of the sludge was adjusted to pH 5.77 and therefore adjusted by addition of 2 M NaOH to 7.5 ±0.5.

The following endpoints are applied to this study data (based on total respiration):

NOEC: 9.5 mg/L

LOEC: 9.5 mg/L

EC50: 157.6 mg/L

The validity criteria applied to this study type were met and therefore the study is considered valid.