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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 June - 09 July 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study was performed according to OECD and EC guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report date:
2009

Materials and methods

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

Test material

Constituent 1
Chemical structure
Reference substance name:
1-(1,3-dihydroxypropoxy)propane-1,3-diol; 3-{3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]-2-hydroxypropoxy}propane-1,2-diol; nonane-1,2,4,5,6,8,9-heptol
EC Number:
915-741-3
Cas Number:
25618-55-7
Molecular formula:
not applicable - multi-constituent substance
IUPAC Name:
1-(1,3-dihydroxypropoxy)propane-1,3-diol; 3-{3-[3-(2,3-dihydroxypropoxy)-2-hydroxypropoxy]-2-hydroxypropoxy}propane-1,2-diol; nonane-1,2,4,5,6,8,9-heptol
Constituent 2
Reference substance name:
Polyglycerol-3
IUPAC Name:
Polyglycerol-3
Details on test material:
- Name of test material (as cited in study report): Polyglycerol-3
- Substance type: organic liquid
- Physical state: Colourless to pale yellow viscous liquid
- Analytical purity:
27.9% Diglycerol
46.0% Triglycerol
17.9% Tetraglycerol
5.6% Pentaglycerol
2.6% Hexaglycerol and higher
- Purity test date: no data
- Lot/batch No.: RBA081008A
- Expiration date of the lot/batch: 31 May 2010
- Stability under test conditions: stabile

Sampling and analysis

Analytical monitoring:
not required

Test solutions

Vehicle:
no
Details on test solutions:
A stock solution of 0.5 g/l was prepared by adding 0.1257 g test substance to 250 ml of Milli-RO water (tap water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA). Thorough mixing (15 minutes) was used to accelerate dissolution and to ensure homogeneity. Volumes of the stock solution corresponding to the test concentration were then added to the test media. A concentration of 100 mg/l was tested in duplicate.


Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Source: Municipal sewage treatment plant: ‘Waterschap de Maaskant', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
- Preparation of inoculum for exposure: 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 (4.0 g/l of sludge, as used for the test). The pH was 7.8 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.
- Initial biomass concentration: 4.0 g/l (of suspended solids)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Post exposure observation period:
none

Test conditions

Test temperature:
18°C.
pH:
8.2-8.3
Dissolved oxygen:
8.6-8.9
Nominal and measured concentrations:
nominal: 100 mg/l
Details on test conditions:
The synthetic sewage feed (16 ml), activated sludge (200 ml) and an adequate amount of the test substance stock were mixed and made up to 500 ml with Milli-RO water in a 1 litre bottle. The mixture was aerated during the contact time, using a pipette as an aeration device.

After the 3-hour contact time, a well mixed sample of the contents was poured into a 300 ml oxygen bottle, and the flask was sealed with an oxygen electrode connected to a recorder, forcing the air out of the vessel. Oxygen consumption was measured and recorded for approximately 10 minutes. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer.
The pH and temperature were determined in the remaining part of the reaction mixture.

This procedure was repeated for the duplicate concentration. Two controls without test substance were tested in each test series, one at the start and one at the end.

Medium: Adjusted ISO medium, formulated using RO-water (tap-water purified by reverse osmosis; GEON Waterbehandeling, Berkel-Enschot, The Netherlands)
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
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:
NOEC
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:
No significant inhibition of respiration rate of the sludge was recorded at 100 mg Polyglycerol-3 per litre and therefore no further testing was needed. Hence, the EC50 of Polyglycerol-3 exceeded 100 mg/l (based on nominal concentration).
Results with reference substance (positive control):
Ec50 = 7.8 mg/l
Reported statistics and error estimates:
For Polyglycerol-3 no EC50 could be calculated because the test substance proved to be non-toxic (EC50 > 100 mg/l).

Any other information on results incl. tables

none

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this present test, Polyglycerol-3 was not toxic to waste water (activated sludge) bacteria at a nominal concentration of 100 mg/l.