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Ecotoxicological information

Toxicity to microorganisms

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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: Non-GLP guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Concentration of test chemical: 1000 mg/L
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Inoculum: activated sludge from a laboratory wastewater plant treating municipal sewage.
- Initial biomass concentration: dry substance 1 g/L.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
30 min
Post exposure observation period:
None
Test temperature:
20 - 25 °C
Nominal and measured concentrations:
Nominal test concentration: 1000 mg/l
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 1 000 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):
EC 20 approx. 4.5 mg/l
EC 50 approx. 15 mg/l
Respiration rate
Mean blank = 29 mg O2/L*h

test item ref. item
[mg/L] [mg/L]
1000 40 4
respiration
rate
[mg O2/L*h] 27 7 24

inhibition
compared to
blank [%] 7 76 17

Validity criteria fulfilled:
yes
Conclusions:
The results of this supporting study confirms the low toxicity of the test substance towards aquatic micro-organisms of a sewage treatment plant.
Executive summary:

Possible toxic effects of the test substance towards aquatic micro-organisms were examined in a limit-test according to OECD guideline 209 (activated sludge test). Concentration of test chemical was 1000 mg/L.Activated sludge from a laboratory wastewater plant treating municipal sewage was used as inoculum. After an exposure time of 30 min, an EC50 of >1000 mg/L (single concentration level used) was observed.

Description of key information

Test with aquatic microorganisms according to OECD guideline 209:
EC50 >1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

Possible toxic effects of the test substance towards aquatic micro-organisms were examined in a limit-test according to OECD guideline 209 (activated sludge test) by BASF (1991). Concentration of test chemical was 1000 mg/L. Activated sludge from a laboratory wastewater plant treating municipal sewage was used as inoculum. After an exposure time of 30 min, an EC50 of >1000 mg/L (single concentration level used) was observed.

In a further test (BASF 1988), which follows German standard DIN 38412 (part 8) an EC50 value of >10000 mg/L was revealed after 17 h exposure period. The results of the supporting study confirms the observed low toxicity of the test substance towards aquatic micro-organisms of a sewage treatment plant.