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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
Study period:
2000-10-18 - 2001-03-21
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Details on sampling:
Not applicable
Vehicle:
no
Details on test solutions:
not indicated
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Preparation of inoculum for exposure: the activated sludge was filtered trough dried and preweighed Whatman GFC filter papers which were then dried again at approximately 105°C for at least one hour, allowed to cool in a desiccator and reweighed. The mixed liquor suspended solids (MLSS) content of the activated sludge was then calculated. Synthetic sewage was added to the activated sludge and the mixture aerated overnight.
- Pretreatment: no further information is given.
- Initial biomass concentration: before test start, the MLSS content was determined and adjusted to 4 g/L by addition of dechlorinated tap water.
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
not indicated
Hardness:
not indicated
Test temperature:
18.1-19.1°C
pH:
7.5-8.2
Dissolved oxygen:
not indicated
Salinity:
not indicated
Nominal and measured concentrations:
not indicated
Details on test conditions:
TEST SYSTEM
- Test vessel: BOD flasks
- Aeration: permanent aeration during incubation time with a Pasteur pipette connected to a laboratory supply of oil-free compressed air.
- No. of culture flasks per concentration (replicates): 1 at 1 and 10 mg/L ,3 at 100 mg/L
- No. of vessels per control (replicates): 2
- Suspended solids concentration: 4.0 g/L mixed liquor suspended solids

EFFECT PARAMETERS MEASURED : Oxygen measurement

TEST CONCENTRATIONS:
1, 10, 100 mg/L
Reference substance (positive control):
yes
Remarks:
3,5- Dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
9.5 mg/L
Conc. based on:
other: reference substance
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 8.0 - 11.2 mg/L
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
> 100 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.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
other: EC80
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
not indicated
Results with reference substance (positive control):
The EC50 of the reference substance was determined to be 9.5 mg/L; this is in the accepted range of 5 to 30 mg/L for 3,5- Dichlorophenol.
Reported statistics and error estimates:
not indicated

O2 concentrations, respiration and inhibition rates of the test and the reference substance





































































Test mixture (mg/L)



Respiration rate (mg O2/g/h)



% inhibition



                 Control 1               



25.0



-



Test substance



 



1



26.8



0



10



26.3



0



100



21.4



13



100



21.4



13



100



21.7



12



3,5-DCP



 



3



22.1



10



10



10.6



57



32



3.8



85



Control 2



24.2



-


Validity criteria fulfilled:
yes
Conclusions:
The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled.
The specific respiration rate of the control performed at the end of the test series was found to be 24.2 mg O2/g*h. and was 97% of the respiration rate in the control performed at test start (25.0 mg O2/g*h). These results comply with the validity criteria of the test.

The EC50 of the reference substance was determined to be 9.5 mg/L; which is in the accepted range of 5 to 30 mg/L for 3,5- Dichlorophenol.

Oxone Monopersulfate Compound had no biologically significant effect on the respiration rate of activated sludge at any of the concentrations employed.
Executive summary:

Materials and methods


The test was conducted according to OECD Guideline No 209. Activated sludge from Eye Sewage Treatment Works for the treatment of  domestic sewage was used.


EC20 >100 mg /L


EC50 >100 mg /L


EC80 >100 mg /L

Description of key information

For the determination of the toxicity to microorganisms a key and a supporting study are available. In the supporting study the toxicity of KMPS triple salt to the gram negative bacterium Pseudomonas putida was determined in a growth inhibition test, according to the guideline of the German Umweltbundesamt: "Bewertung wassergefährdender Stoffe: Bestimmung der akuten Bakterientoxizität". The key study was conducted according to OECD Guideline 209.

Key value for chemical safety assessment

EC50 for microorganisms:
179 mg/L
EC10 or NOEC for microorganisms:
108 mg/L

Additional information

Key study


The test was conducted according to OECD Guideline No 209. Activated sludge from Eye Sewage Treatment Works for the treatment of  domestic sewage was used. The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled. The specific respiration rate of the control performed at the end of the test series was found to be 24.2 mg O2/g*h. and was 97% of the respiration rate in the control performed at test start (25.0 mg O2/g*h). These results comply with the validity criteria of the test. The EC50 of the reference substance was determined to be 9.5 mg/L; which is in the accepted range of 5 to 30 mg/L for 3,5- Dichlorophenol. Oxone Monopersulfate Compound had no biologically significant effect on the respiration rate of activated sludge at any of the concentrations employed.


EC20 >100 mg /L


EC50 >100 mg /L


EC80 >100 mg /L


 


 


Supporting study


In the supporting study the toxicity of KMPS triple salt to the gram negative bacterium Pseudomonas putida was determined in a growth inhibition test, according to the guideline of the German Umweltbundesamt: "Bewertung wassergefährdender Stoffe: Bestimmung der akuten Bakterientoxizität". The toxicity threshold, defined as 10% inhibition was determined to be EC10 = 108 mg KMPS triple salt/L.