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Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: basic data given
Qualifier:
according to guideline
Guideline:
ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)
Deviations:
not specified
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
not specified
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
activated sludge
Details on inoculum:
- activated sludge: 6.0 g/l dry mass per liter
- inoculum: 50 ml sludge/ l test volume
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20.2-22.9°C
pH:
7.8-8.1
Dissolved oxygen:
2.1 -9.2 mg/l
Nominal and measured concentrations:
Nominal concentrations:
- test substance: 100, 1000, and 10000 mg/l
- reference substance: 1 and 20 mg/l
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorphenol
Key result
Duration:
3 h
Dose descriptor:
EC0
Effect conc.:
>= 10 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 10 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
20 mg/l 3,5-dichlorophenol obtained 78 % respiration inhibition

The substance was dispersed in the test medium equivalent to a concentration of 10 g/l.

Validity criteria fulfilled:
yes
Conclusions:
Toxicity of DCBS to activated sludge was evaluated by Bayer AG (1989) according to the ISO 8192 -1986/B and no effect was observed up to the highest nominal concentration tested (10000 mg/l) during 3 hours exposure at a pH 7.8 - 8.1 and temperature of 20.2 - 22.9 °C.
Executive summary:

Toxicity of DCBS to activated sludge was evaluated by Bayer AG (1989) according to the ISO 8192 -1986/B and no effect was observed up to the highest nominal concentration tested (10000 mg/l) during 3 hours exposure at a pH 7.8 - 8.1 and temperature of 20.2 - 22.9 °C.

Description of key information

Toxicity of DCBS to activated sludge was evaluated by Bayer AG (1989) according

to the ISO 8192 -1986/B and no effect was observed up to the highest nominal concentration tested (10000 mg/l) during 3 hours exposure at a pH 7.8 - 8.1 and temperature of 20.2 - 22.9 °C.

Key value for chemical safety assessment

EC50 for microorganisms:
10 000 mg/L

Additional information

Should read >10000 mg/L.

In sewage treatment plant, large amount of test substance might be present in both dissolved and undissolved form. To represent a more realistic situation, the tested concentrations are much higher than the water solubility of the test substance (i.e. about 0.002 mg/l). Therefore the reported concentrations represent the combined effect of dissolved and undissolved test substance on the activity of microorganism in the sewage treatment plant.