Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October 5, 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study has been performed according to OECD and EC guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Corsair Clear #12
- Substance type: Soft waxy beige solid
- Physical state: Solid
- Stability under test conditions: stable
- Storage condition of test material: At room temperature in the dark

Sampling and analysis

Analytical monitoring:
not required

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Corsair Clear #12 was weighed on a thin coverglass and as such (with the coverglass) added to Milli-RO water. Initial loading rates of 200 mg/l were stirred for 25¼ or 25¾ hours in the test bottles. Subsequently, synthetic sewage feed and sludge were added resulting in a loading rate of 100 mg/l. A loading rate of 100 mg/l was tested in duplicate. Optimal contact between the test substance and test medium was ensured applying continuous aeration and stirring.

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
The sludge was coarsely sieved, washed and diluted with ISO-medium. A small amount of the sludge was weighed and dried overnight at ca. 105°C to determine the amount of suspended solids (4.1 g/l of sludge, as used for the test). The pH was 7.6 on the day of testing. The batch of sludge was used one day after collection; therefore 50 ml of synthetic sewage feed was added per litre of activated sludge at the end of the collection day. The sludge was kept aerated at test temperature until use.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Post exposure observation period:
After the exposure period, oxygen consumption was measured and recorded for approximately 10 minutes.
Measurement of pH.

Test conditions

Hardness:
not applicable
Test temperature:
18.6 - 20.4 °C
pH:
7.7 - 8.1
Dissolved oxygen:
measured and recorded for approximately 10 minutes (the linear part of the respiration curve, was generally between 2.5 and 6.5 mg O2/l).
Salinity:
not applicable
Nominal and measured concentrations:
a loading rate of 100 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type : open
- Material, size, headspace, fill volume: all glass, approximately 300 ml oxygen bottles (measuring) and 1 litre test bottles (exposure).
- Aeration: continuously during exposure with clean, oil-free air
- No. of organisms per vessel:200 ml activated sludge (suspended solids 4.1 g/l) in 500 ml final volume
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): Two controls without test substance were tested in each test series, one at the start and one at the end.
- Biomass loading rate: 200 ml activated sludge (suspended solids 4.1 g/l) in 500 ml final volume

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-RO water (tap water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA).


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The respiration rate from each vessel, in mg O2/l/hr, was calculated from the linear part of the respiration curve, which was generally between 2.5 and 6.5 mg O2/l. If applicable (not for this test substance) the EC50 was determined.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrations
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: loading rate
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
Max 18% inhibition at a loading rate of 100 mg/l.
The EC50-value for Corsair Clear #12 exceeded a loading rate of 100 mg/l (above the water solubility).

Results with reference substance (positive control):
- Results with reference substance valid? Yes
- Relevant effect levels: The EC50 for the reference substance (3,5-dichlorophenol) was within the acceptable limits of
5-30 mg/l, with 40% inhibition at 5.0 mg/l and 79% inhibition at 30 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this present test, the EC50-value for Corsair Clear #12 exceeded a loading rate of 100 mg/l, the regulatory limit concentration.