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Toxicity to microorganisms

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Description of key information

In a GLP compliant test performed according to OECD guideline 209, the test item showed significant inhibitory effects on activated sludge after 3 hours of exposure at concentrations from 1 to 320 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
33 mg/L
EC10 or NOEC for microorganisms:
0.65 mg/L

Additional information

The influence of GM102E on the respiration rate of activated sludge was investigated after a contact time of 3 hours according to OECD guideline No. 209 and in compliance with GLP.

The final test was performed based on the result of a preceding combined limit/range-finding test. Six concentrations, ranging from 1.0 to 320 mg/l, increasing with a factor 3.2 were tested with five replicates per concentration and six replicates for an untreated control group.

As a positive control, the reference item 3,5 -dichlorophenol was tested under identical test conditions, at concentrations of 2.0, 5.0 and 12 mg/l. The EC50 of 3,5-dichlorophenol was in the accepted range of 2 to 25 mg/l for total respiration which showed a normal sensitivity of the activated sludge.

GM102E was toxic to the micro-organisms at all concentrations tested. The inhibitory effect of GM102E on aerobic waste water (activated sludge) bacteria increased with increasing concentration, ranging from 13% inhibition at 1.0 mg/l to 80% at 320 mg/l.

The 3-hour NOEC and ECx nominal values were as follows:

EC10 = 0.65 mg/L

EC20 = 2.5 mg/L

EC50 = 33 mg/L

Some deviations were observed but they didn’t influence the validity of the test.