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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1999-09-14 to 1999-11-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD Guideline study under GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report date:
1999

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
ISO 8192
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
Silicophosphonat
IUPAC Name:
Silicophosphonat
Details on test material:
- Name of test material (as cited in study report): Silicophosphonat
- Physical state: Liquid

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
-

Test solutions

Vehicle:
no
Details on test solutions:
The stock solution was adjusted to pH 7,7 (before 11)

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Activated sludge from laboratory wastewater plants treating municipal sewage. Concentration of dry substance 1 g/L.
The inoculum was washed, brought to a concentration of 5 g/L dry substance and aerated for about 24 h. 50 mL were added to a total volume of 250 mL to obtain a concentration of 1 g/L dry substance in the test.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
30 min
Post exposure observation period:
-

Test conditions

Hardness:
not given
Test temperature:
20 +/-2 °C
pH:
7.2 -7.3 after initial correction
Dissolved oxygen:
during aeration: >2.5 mg/L
imediately before measurement: >6.5 mg/L
Nominal and measured concentrations:
100 mg /L (Nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 250-mL-Erlenmeyer vessel
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 3
- No. of vessels per reference substance (replicates):3


TEST MEDIUM / WATER PARAMETERS
- Total volume: 250 mL
- Media: 8 mL /vessel100-fold concentrated OECD medium


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
EC20, EC50, EC80 by determination of Oxygen consumption

TEST CONCENTRATIONS FOR REFERNCE SUBSTANCE
1, 10, 100 mg/L
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol

Results and discussion

Effect concentrations
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
none
Results with reference substance (positive control):
- Results with reference substance valid? yes

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Substance is not toxic for microorganisms under the conditions used. Disturbances in the biodegradation process of activated sludge are not expected if the test substance is correctly introduced into adapted wastewater treatment plants at low concentrations.
Executive summary:

A study was performed to assess the inhibitory effect of Silicophosphonat on the respiration of activated sewage sludge. The study was conducted according to OECD 209 at a limit concentration of 1000 mg/l. 3,5 -Dichlorophenol was tested concurrently as a reference substance to demonstrate the satisfactory performance of the procedure. The EC50 (Respiration inhibition) value for PD 132408 was determined to be > 1000 mg/L for the 30 min contact time.