Dichlorodicyclopentylsilane

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:

1997-04-18 until 1997-08-14

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:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): Silane CP 2
- Physical state: liquid
- Analytical purity: 96.3% (GC)
- Impurities (identity and concentrations): as stated in substance data
- Composition of test material, percentage of components: as stated in substance data
- Lot/batch No.: 10466 QB
- Expiration date of the lot/batch: 1997-12-01
- Stability under test conditions: reaction to hydrolysis product
- 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 (ARA Ergolz II, Füllinsdorf/Switzerland)
- Method of cultivation: sludge was washed by centrifugation, the supernatant liquid phase was decanted, the solid material resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet sludge to its dry weight determined. Based on this ratio calculated aliquots of washed sludge suspension (4g dry material/L) were made up with an aqueous mineral medium (pH 7.4) and aerated until use.
- Preparation of inoculum for exposure: Immediately before use, the dry weight of the activated sludge was determined to be 5.2 g/L, and diluted with tap water to a dry weight of 4 g/L. The pH was adjusted to 7.8 with 0.5 mol/L sulfuric acid.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2.6 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: in accordance with Guideline
- Test temperature: 20 - 21 °C
- pH: 7.3 - 7.4 (start of the test)
- pH adjusted: no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: wide-necked reagent bottles (with conical shoulder)
- Number of culture flasks/concentration: 14 bottles (test substance + inoculum), 14 bottles (inoculum), 14 bottles (reference compound Aniline + inoculum), 8 bottles (test substance + reference compound Aniline + 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, dissolved oxygen concentration was 8.5 mg/L
- Measuring equipment: airtight system with a O2-electrode using a WTW OXI 539 meter


SAMPLING
- Sampling frequency: measurement was performed on exposure days 0, 2, 7, 12, 14, 21 and 28


CONTROL AND BLANK SYSTEM
- Inoculum blank: 0.5 ml filtered inoculum/L test medium
- Procedure control: 2.0 mg Aniline/L + 0.5 ml inoculum/L test medium
- Toxicity control: 1.2 mg test substance/L + 1.1 mg Aniline/L + 0.5 ml inoculum/L test medium

Reference substance

Reference substance:

aniline

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Remarks on result:

other: No degradation has been observed during the test

Details on results:

The reference compound Anline was biodegraded by an average of 60.6% by exposure day 14 and reached an average biodegradation rate of 83.6% by the end of the study, thus confirming suitability of the activated sludge. In the toxicity control, an average biodegradation of only 17.5 % (instead of at least 25% as indicated in the guidelines) was noted within 14 days of exposure, thus possibly indicating a slightly 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:

Silane CP 2 is not readily biodegradable.

Executive summary:

Silane CP 2 was investigated for its ready biodegradability in the "Close Bottle Test" when exposed to aerobic activated sludge from a domestic waste water treatment plant over a period of 28 days. Under the test conditions Silane CP 2 (tested as its water-soluble hydrolysis product dicyclopentylsilanediol) was found to be non-biodegradable over the 28 -day exposure period. The reference substance Aniline reached the level for ready biodegradability, thus confirming suitability of the activated sludge. In the toxicity control an average biodegradation of only 17.5% (instead of at least 25% as indicated in the testing guidelines) was noted within 14 days of exposure, thus possibly indicating a slightly toxic effect of the test substance (as its water-soluble hydrolysis product dicyclopentylsilanediol) on the microorganisms.