Tetramethylsilane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-05-06 to 2002-07-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

Secondary effluent from a sewage treatment plant dealing with predominantly domestic sewage. To prepare the effluent, the sample was filtered through a coarse filter, and first 200 mL discarded. The rest of the filtrate was kept aerobic until use. The number of bacteria was determined to be 2 E08 bacteria per litre of final volume of the test medium.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS

- Test temperature: Dilution water 20.0 °C. Water bath 19.8 °C.

- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 300 ml BOD bottles

- Number of culture flasks/concentration: 18 blank; 18 reference, 18 test substance, 6 toxicity control

- Test performed in closed vessels due to significant volatility of test substance: yes


SAMPLING
- Sampling frequency: Blank, reference and test substance bottles were removed in duplicate after 3, 7, 10, 14, 17, 21, 24 and 28 days fro immediate dissolved oxygen analysis. Toxicity control bottles were analysed after 7 and 14 days. (Two bottles were analyased before incubation.) Oxygen measuring instrument: OXI DIGI 530 with a Tri Oxmatic-EO 200 oxygen electrode

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes

- Abiotic sterile control: No

- Toxicity control: Yes

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

0.7

Sampling time:

28 d

Details on results:

Degradation of reference compound: 75.3% by 14 days, and reached an average biodegradation of 84.9% by the end of the 28-d exposure period.

Toxicity control: 25.9% degradation after 14 days.

Table 1: Dissolved oxygen concentration (mg O₂/l) and calculated % biodegradation for inoculum control, test substance, toxicity control and reference substance

Type of suspension	0		3		7		10		14		17		21		24		28
	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg	mg O2/l	(%) biodeg
Inoculum control (mean of two vessels)	8.95	-	9.00	-	8.97	-	8.99	-	8.87	-	8.82	-	8.66		8.78	-	8.55	-
Test sample (mean of two vessels)	9.06	-	9.06	0.9	8.96	2.2	9.00	1.7	8.77	3.6	8.85	1.3	8.64	2.2	8.62	4.7	8.62	0.7
Toxicity control (mean of two vessels)	9.00	-	-	-	6.85	24.3	-	-	6.62	25.9	.	.	.	.	.	.	.	.
Reference substance (mean of two vessels)	9.05	-	7.56	49.4	7.03	65.5	6.81	72.9	6.62	75.3	6.59	74.7	6.42	75.0	6.39	79.8	6.00	84.9

 

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

A biodegradation of 0.7% in 28 days was determined for the substance in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Description of key information

Biodegradation in water: screening tests: 0.7% in 28 d (OECD 301D; EU Method C4-E)

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

A ready biodegradation value of 0.7% in 28 days was determined for the substance in accordance with OECD 301D Test Guideline and in compliance with GLP. The result is considered to be reliable.