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:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Remarks:
potential deviations would be documented in amendments
GLP compliance:
yes (incl. certificate)
Remarks:
GLP-Conformity All procedures according to the principles of GLP (Chemikaliengesetz §19a and §19b and annexes 1 and 2 from 28. Aug. 2013, published in Federal Law Gazette, Germany (BGBl) No. 55/2013 as of 06. Sep. 2013, and further revisions).

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
additive
Test material form:
liquid
Details on test material:
- State of aggregation: not applicable
- Activation: not required
water as a additive
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: The test material is representative of the registered substance
- Expiration date of the lot/batch: not relevant
- Purity test date: not relevant

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature in the dark
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: soluble

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: none
- Preliminary purification step (if any): none

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Activated sludge from a biologic sewage treatment plant was used as inoculum. The chosen plant is treating mostly domestic sewage.
The sludge was collected from the activation basin of the sewage treatment plant Edenkoben on 23. Feb. 2018, batch no: 20180223.
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 3980 mg of sus-pended solids/L.
Duration of test (contact time):
28 d
Details on study design:
This study was performed in order to evaluate aerobic elimination and degradation potential in a test for ready biodegradability, using a test item concentration of nominally 20 mg organic carbon/L (corresponding to 95.6 mg test item).
The test item in a mineral medium was inoculated and incubated under aerobic conditions in the dark. The amount of DOC in the test solution due to the inoculum was kept as low as possible compared with the amount of organic carbon due to the test item. Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without test item. A positive control was run in parallel to check the operation of the procedures. Degradation was followed by determining the carbon dioxide produced. Measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation.
The test lasted for 28 days.

Test performance
The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide is achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air is led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.
Magnetic stirrers were used to prevent deposition of inoculum.
The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels.

Instruments and Devices
The following instruments and devices were used.
• Data logger for temperature
• Analytical scales
• Adjustable pipettes with one-way tips
• Carbon analyser
• pH-meter
• Heating chamber
• Standard laboratory equipment
Usage and, if applicable, calibration of all instruments following the corresponding SOP in the current edition.

Reference substance
Reference substance:
aniline
Remarks:
positive control

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
0
Sampling time:
28 d

Any other information on results incl. tables

pH values

Day

Blank Control 1

Blank Control 2

Positive Control 1

Positive Control 2

Test 1

Test 2

Abiotic Control

Toxicity Control

28

7.4

7.4

7.7

7.7

7.6

7.6

7.0

7.7

Details on results


Day

Blank Control 1

Blank Control 2

Positive Control 1

Positive Control 2

Test 1

Test 2

Abiotic Control

Toxicity Control

2

0.56

0.08

0.62

1.17

0.49

0.04

0.34

0.74

4

1.09

0.59

0.99

5.72

0.80

0.44

0.33

2.20

7

1.68

1.73

8.77

12.44

1.17

0.86

0.33

11.70

9

1.80

3.09

14.20

14.00

1.36

1.03

0.16

12.55

11

2.12

2.81

15.76

15.79

1.51

1.46

0.24

13.47

14

2.28

2.72

16.61

16.76

1.52

1.43

0.24

13.49

18

2.50

3.21

19.04

18.93

1.67

1.74

0.22

14.78

23

2.94

4.01

22.37

20.33

1.73

1.76

0.22

15.67

29

3.08

4.33

23.24

21.18

1.64

1.82

-0.01

15.30

Degradation values in %

Day

Positive Control 1

Positive Control 2

Positive Control Mean

Test 1

Test 2

Test Mean

Abiotic Control

Toxicity Control

2

1.5

4.2

2.9

0.8

-1.4

-0.3

1.7

1.0

4

0.8

24.4

12.6

-0.2

-2.0

-1.1

1.6

3.2

7

35.3

53.6

44.5

-2.6

-4.2

-3.4

1.6

23.2

9

58.7

57.7

58.2

-5.3

-7.0

-6.2

0.8

23.5

11

66.4

66.6

66.5

-4.7

-5.0

-4.9

1.2

25.6

14

70.5

71.3

70.9

-4.8

-5.3

-5.1

1.2

25.5

18

80.9

80.3

80.6

-5.9

-5.5

-5.7

1.1

27.7

23

94.4

84.2

89.3

-8.6

-8.5

-8.6

1.1

28.3

29

97.6

87.3

92.4

-10.2

-9.3

-9.8

0.0

26.9

Because the values of day 29 are the sum of the IC values in both scrubber flasks, an decrease of degradation can be observed. As the measured IC values in the test flasks are very low, measurement uncertainties lead to negative degradation values while in fact no degradation has taken place.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
No biodegradation could be detected.  
A 10-day-window could not be determined.
The test item is considered as not readily biodegradable within 28 days
Abiotic degradation was not detected
Executive summary:

The aerobic ready biodegradability of the test item was determined in the CO2 Evolution Test following OECD 301B resp. EU C.4-C. In very dilute domestic sludge, no degradatioon of the test item was observed after the 10-d-window and after 28 d at the end of the test. As degradation missed the pass level of 60 % in the course of the test, the substance is considered as not readily biodegradable.