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Toxicity to microorganisms

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Description of key information

The EC50 (3 hours) of Bourgeonal is 80 mg/l. The NOEC is 31.6 mg/L.

Key value for chemical safety assessment

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

Additional information

The respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed is measured after a contact time of three hours. The respiration rate of the same activated sludge in the presence of various concentrations of the test substance under otherwise identical conditions is also measured. Five concentrations were tested: 1, 3.2, 10, 31.6 and 100mg/L. Only at a test concentration of 100 mg/L was significant inhibition of the respiration observed. Therefore the NOEC is considered to be 31.6 mg/L. For estimating the EC50 (3 hours) a linear relationship between % inhibition and the common logarithm of the test substance concentration was assumed for concentrations ranging from 31.6 to 100mg/l. Using this equation the concentration corresponding to 50% inhibition was calculated to be ~ 80 mg/l.

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