Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 January 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study has been performed according to OECD and/or EC guidelines and according tot GLP principles

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

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:
according 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): 7-ADCA
- Substance type: White powder
- Physical state: Solid
- Analytical purity: 99.0%
- Lot/batch No.: D212013
- Expiration date of the lot/batch: 28 February 2011 (retest date)
- Stability under storage conditions: Stable
- Storage condition of test material: In refrigerator (2-8°C) in the dark
- Stability in water Not indicated
- Solubility in water 0.1% (20°C)

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
Since 7-ADCA was hardly soluble in water test concentrations were prepared separately in
Milli-RO water (tap water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA).
Two 1 litre test bottles were filled with 250 ml of test substance mixtures with initial loading rates of 200 mg/l. These mixtures were treated with ultrasonic waves for 5 minutes and stirred in closed brown glass bottles for 24 hours. Subsequently, 16 ml synthetic sewage feed, 200 ml sludge and Milli-RO water up to 500 ml were added resulting in a loading rate of 100 mg/l . This loading rate was tested in duplicate. Optimal contact between the test substance and test organisms was ensured applying continuous aeration and stirring during the 3 hour exposure period.

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 (4.2 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.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
3 h
Post exposure observation period:
Oxygen consumption was measured and recorded for approximately 10 minutes after the 3 hours exposure period.

Test conditions

Test temperature:
between 18.9 and 19.5°C.
pH:
7.9 - 8.0
Dissolved oxygen:
Oxygen consumption:
Controls for 7-ADCA:60-62 mg O2/l/h
7-ADCA:59-60 mg O2/l/h
The oxygen concentration at the start of the measurements was at least 6.5 mg O2/l
Nominal and measured concentrations:
Loading rate at 100 mg/l
Details on test conditions:
TEST SYSTEM
- Type (delete if not applicable): open
- Material, size, headspace, fill volume:All glass, approximately 300 ml oxygen bottles and 1 litre test bottles.
- Aeration:During exposure with clean, oil free air
- No. of vessels per concentration (replicates):2
- No. of vessels per control (replicates):2
- Biomass loading rate: 1.7 g/l suspended solids in the final mixture

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:Tap-water purified by reverse osmosis (Milli-RO)

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.

TEST CONCENTRATIONS
limt at a loading rate of 100 mg/l
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 7-ADCA per litre. The duplicate measurement confirmed the result of the first measurement. Therefore, no further testing was needed. Hence, the EC50 of 7-ADCA exceeded a loading rate of 100 mg/l.
Results with reference substance (positive control):
The EC50 of 3,5-dichlorophenol was in the accepted range of 5-30 mg/l (11 mg/l)
Reported statistics and error estimates:
The percentage inhibition was plotted against the logarithm of the concentrations. The EC50 for the reference substance, was determined using linear regression analysis.
For 7-ADCA no EC50 could be calculated because the test substance proved to be non-toxic (EC50 > 100 mg/l).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this present test, 7-ADCA was not toxic to waste water (activated sludge) bacteria at a loading rate of 100 mg/l (EC50 > a loading rate of 100 mg/l).