Registration Dossier

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:
28 May to 25 June 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Recent study conducted by a GLP certified laboratory in accordance with a suitable study guideline.

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
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
tris(propan-2-yl)silyl 2-methylprop-2-enoate
EC Number:
700-182-8
Cas Number:
134652-60-1
Molecular formula:
C13 H26 O2 Si
IUPAC Name:
tris(propan-2-yl)silyl 2-methylprop-2-enoate
Details on test material:
- Name of test material (as cited in study report): TIS-M
- Lot/batch No.: 9925
- Expiration date of the lot/batch: 2 December
- Storage condition of test material: At room temperature: 15-25ºC

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge:The activated sludge was supplied from the sewage plant for domestic sewage in Veszprém, Hungary.
- Preparation of inoculum for exposure: The activated sludge used for this study was washed by centrifugation (for 10 min.) and the supernatant liquid phase was decanted. The solid material was re-suspended in isotonic saline solution and again centrifuged (for 10 min.). This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 4 g dry material per litre were mixed with test water and then aerated until use. Before use the sludge was filtered through cotton wool.
- Concentration of sludge: 4 g dry material per litre.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
2.9 mg/L
Based on:
COD
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature: 21.8-23.2°C in an incubator.
- pH: 7.40
- pH adjusted: no
- Aeration of dilution water:
- Suspended solids concentration:
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: BOD bottles (300 ml) with special neck and glass stoppers.
- Number of culture flasks/concentration: 10
- Method used to create aerobic conditions: The test medium was aerated for 20 minutes and allowed to stand for about 20 hours at the test temperature.
- Measuring equipment: The COD (chemical oxygen demand) of the test item were determined in using Lovibond® COD Measuring System and the oxygen concentrations were measured with oxygen meter with a stirring O2 electrode.
- Test performed in open system: yes

CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculum control contains the inoculum only.
- Toxicity control: contains test item, reference item and inoculum.

Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Preliminary study:
The 14-d preliminary test measured the chemical oxygen demand (COD) to be 2.10 ±0.03 mg test item, which lead to the decision that the required test item concentration would be 2.9 mg/L for the study.
Test performance:
Based on the results observed, the test performance was acceptable and within current acceptable limits.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
8.2
Sampling time:
28 d
Details on results:
- Under the test conditions the percentage biodegradation of TIS-M reached a mean of 8.2 % after 28 days based on the measured COD of the test item. The test item can therefore be considered to be not ready biodegradable. According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD.
- The reference item Sodium benzoate was sufficiently degraded to a mean of 82.5% after 14 days, and to a mean of 86.7 % after 28 days of incubation, based on ThODNH4, thus confirming the suitability of the used activated sludge inoculum.
- In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 45.3 % biodegradation was noted within 14 days and 46.6% biodegradation after 28 days of incubation. According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 2.9 mg/L on the activated sludge microorganisms because degradation was >25 % within 14 days.

BOD5 / COD results

BOD5 / COD
Parameter:
COD
Value:
2.1 mg O2/g test mat.
Results with reference substance:
The reference item Sodium benzoate was sufficiently degraded to a mean of 82.5% after 14 days, and to a mean of 86.7 % after 28 days of incubation, based on ThODNH4, thus confirming the suitability of the used activated sludge inoculum. According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD.

Any other information on results incl. tables

Table 2. Dissolved Oxygen Concentrations at Different Time Intervals during the Exposure Period of 28 Days:

Treatment

Concentration [mg/L]

Flask No.

0

mg O2/L after

7

n days of exposure 14          21

28

 

2.9

1a

8.1

7.1

6.9

6.6

6.3

Test item

2.9

1b

8.1

7.1

7.0

6.6

6.4

 

2.9

mean

8.10

7.10

6.95

6.60

6.35

 

3.6

2a

8.2

2.7

2.5

2.1

1.7

Reference item

3.6

2b

8.2

2.7

2.3

2.1

1.8

 

  3.6

mean

8.20

2.70

2.40

2.10

1.75

 

  -

3a

8.4

7.6

7.5

7.3

7.1

Inoculum control

-

3b

8.3

7.5

7.5

7.2

7.1

 

  -

mean

8.35

7.55

7.50

7.25

7.10

 

-

4a

8.1

2.1

1.7

1.4

1.1

Toxicity control

Test item: 2.9 Reference item: 3.6

4b

8.1

2.1

1.7

1.4

1.2

 

 

mean

8.10

2.10

1.70

1.40

1.15

Table 3: Oxygen Depletion at Different Time Intervals during the Exposure Period of 28 Days

 

Concentration

Flask

 

mg O2/L after n

days of exposure

 

Treatment

[mg/L]

No.

7

14

21

28

  Test item

  2.9

1a

0.20

0.35

0.40

0.55

 

 

 

 

 

  Test item

  2.9

1b

0.20

0.25

0.40

0.45

  Reference item

  3.6

2a

4.70

4.85

5.00

5.25

 

 

 

 

 

  Reference item

  3.6

2b

4.70

5.05

5.00

5.15

Toxicity

Test item: 2.9

4a

5.20

5.55

5.60

5.75

control

Reference item: 3.6

4b

5.20

5.55

5.60

5.65

oxygen depletion : (mt0 - mtx) - (mbo - mbx), where:

- mt0 : oxygen concentration (mg/L) of test group on day 0 (1a, 2a, 4a and 1b, 2b, 4b from Table 2)

- mtx: oxygen concentration (mg/L) of test group on day x (1a, 2a, 4a and 1b, 2b, 4b from Table 2)

- mb0: oxygen concentration (mg/L) of inoculum blank on day 0 (mean of 3a and 3b from Table 2)

- mbx: oxygen concentration (mg/L) of inoculum blank on day x (mean of 3a and 3b from Table 2)

Table 4. BOD at Different Time Intervals during the Exposure Period of 28 Days:

 

Concentration

Flask

 

BOD after n days of exposure

 

Treatment

[mg/L]

No.

7

14

21

28

   Test item

   2.9

1a

0.07

0.12

0.14

0.19

 

 

 

 

 

   Test item

   2.9

1b

0.07

0.09

0.14

0.16

  Reference item

  3.6

2a

1.31

1.35

1.39

1.46

 

 

 

 

 

   Reference item

  3.6

2b

1.31

1.40

1.39

1.43

Toxicity

Test item: 2.9

4a

0.80

0.85

0.86

0.88

control

Reference item: 3.6

4b

0.80

0.85

0.86

0.87

BOD = (mg O2 of T.i. and/or R.i.-mg O2 of i.control) / (mg T.i. and/or in R.i. in flask) = mg O2/mg T.i and/or R.i.

where: T.i. = test item R.i. = reference item i.control = inoculum control.

Table 5. Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days

Treatment

Concentration [mg/L]

Flask No.

Percent of biodegradation after n days of exposure 7               14              21              28

  Test item

   2.9

1a

3.3

5.7

6.6

9.0

Test item

2.9

1b

3.3

4.1

6.6

7.4

  Test item

   2.9

mean

3.3

4.9

6.6

8.2

  Reference item

   3.6

2a

78.3

80.8

83.3

87.5

Reference item

3.6

2b

78.3

84.2

83.3

85.8

  Reference item

   3.6

mean

78.3

82.5

83.3

86.7

 

 

4a

42.5

45.3

45.7

47.0

Toxicity

Test item: 2.9

4b

42.5

45.3

45.7

46.2

control

Reference item: 3.6

 

 

 

 

 

 

 

mean

42.5

45.3

45.7

46.6

Biodegradation % = (BOD ( mg O2/mg T.i. or R.i) / COD (mg O2/mg T.i.) or THODNH4 (mg O2/mg R.i.)) x100

where: T.i. = test item R.i. = reference item i.control = inoculum control.

COD of test item = 2.10 ± 0.03 mg O2/mg test item

ThODNH4 of reference item = 1.67 mg O2/mg reference item

The biodegradation in the toxicity control was calculated according to the following formula:

(BOD (mg O2/mg T.i. and R.i.) / [COD(mgO2/mgT.i.) + ThODNH4 (mg O2/mg R.i)]* 1/2) x 100

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
-The registered substance was determined to be not ready biodegradable, as the percentage biodegradation reached a mean of 8.2 % after 28 days based on the measured COD of the test item.
-In the toxicity control containing both the registered substance and the reference item Sodium benzoate, a mean of 45.3 % biodegradation was noted within 14 days and 46.6% biodegradation after 28 days of incubation. According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 2.9 mg/L on the activated sludge microorganisms because degradation was >25 % within 14 days.
Executive summary:

The biodegradibility of the registered substance was assessed according to the EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test) method. Procedure, inoculum and toxicity controls were also used. After 28 days the registered substance was determined not to be ready biodegradable, as the percentage biodegradation reached a mean of 8.2 % after 28 days based on the measured COD of the test item. It was also determined that the registered substance can be assumed not to be inhibitory at the applied concentration level of 2.9 mg/L on the activated sludge microorganisms because degradation was >25 % within 14 days, according to the results of the toxicity control and the guideline used.