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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-05-15 until 2002-07-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: OECD study under GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
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): CAVASOL W6 HP
- Physical state: solid powder
- Impurities (identity and concentrations): as stated in substance data
- Composition of test material, percentage of components: as stated in substance data
- Lot/batch No.: 63B001
- Expiration date of the lot/batch: 2003-02-28
- Stability under test conditions: stable
- Storage condition of test material: in original container, at room temperature, in the dark

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source: domestic waste water treatment plant (Waterschaap de Maaskant, 's Hertogenbosch, The Netherlands)
- Method of cultivation: sludge was washed, the supernatant liquid phase was decanted.
- Concentration of solids: 3.8 g/l in the concentrated sludge
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
12 mg/L
Based on:
ThOD/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: in accordance with Guideline
- pH: 7.4 - 7.6
- pH adjusted: no
- Continuous darkness: yes
- Temperature: 22°C


TEST SYSTEM
- Culturing apparatus:2 litre all-glass brown coloured bottles
- Number of culture flasks/concentration: 2 bottles (test substance + inoculum), 2 bottles (inoculum), 1 bottle (reference compound sodium acetate + inoculum), 1 bottle (test substance + reference compound sodium acetate + inoculum)
- Test substance: test substance was directly mixed with test medium and allow to stir on a magnetic stirrer for about 6 hours in the dark; in this way the test substance reacted to the water-soluble hydrolysis product dicyclopentylsilanediol; concentration: 2.6 mg test substance/L + 0.5 ml inoculum/L test medium
- Method used to create aerobic conditions: aeration of test medium


SAMPLING
- Sampling frequency: measurement was performed on exposure days 0, 2, 5, 7, 9, 14, 19, 23, 27 and 29


CONTROL AND BLANK SYSTEM
- Inoculum blank: 0.5 ml filtered inoculum/L test medium
- Procedure control: 40 mg/l soium acetate + inoculum/ test medium
- Toxicity control: test substance + sodium acetate + inoculum



Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
1
Sampling time:
2 d
Parameter:
% degradation (CO2 evolution)
Value:
3
Sampling time:
7 d
Parameter:
% degradation (CO2 evolution)
Value:
3
Sampling time:
14 d
Parameter:
% degradation (CO2 evolution)
Value:
6
Sampling time:
23 d
Parameter:
% degradation (CO2 evolution)
Value:
11
Sampling time:
29 d
Details on results:
The reference compound sodium acetate was biodegraded by 60 % by exposure day 14 and reached an biodegradation rate of 70% by the end of the study, thus confirming suitability of the activated sludge. In the toxicity control, an average biodegradation of 35 % was noted within 14 days of exposure, thus not indicating a toxic effect of the test substance on the microorganisms.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Cavasol W6 HP is not readily biodegradable.
Executive summary:

Cavasol W6 HP was investigated for its ready biodegradability in the "Modified Sturm Test" when exposed to aerobic activated sludge from a domestic waste water treatment plant over a period of 28 days. Under the test conditions Cavasol W6 HP was found to be not readily biodegradable over the 28 -day exposure period. The reference substance sodium acetate reached the level for ready biodegradability, thus confirming suitability of the activated sludge. In the toxicity control an biodegradation of only 35% was noted within 14 days of exposure, thus not indicating a toxic effect of the test substance on the microorganisms.