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Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
6 Sep 2013 to 11 Oct 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
March, 2006
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Name of test material (as cited in study report): Alpha-sulfo-C12/70-Fettsäure-di-Na-Salz 87,0% AS
- Date of production: 18 June 2013
- Batch No.: Ra-He 20212-023
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Activated sludge from the wastewater treatment plant of Mannheim. Concentration of dry substance: 30 mg/L.
Duration of test (contact time):
28 d
Initial conc.:
46.8 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- pH: 7.4 at the begin of the exposure, 7.1 - 7.3 at the end of the exposure.

TEST SYSTEM
- Culturing apparatus: test volume 1500 mL. 1376 - 1473 mL/vessel deionized water, 19.5 mL/vessel mineral medium, 7.5 mL/vessel Inoculum (6g/L dry matter) and 20 mg/L TOC of the test substance or reference substance.
- Number of culture flasks/concentration: 2 vessels, 69.4 mg test substance/vessel (nominal value).

SAMPLING
- Sampling frequency: day 0, 4, 7, 11, 14, 18, 22, 25, 28 and 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes.
- Reference substance concentration: 20 mg/L (TOC, nominal).
- Inhibition control: 20 mg/L (TOC concentration) test substance, and 20 mg/L (TOC concentration) reference substance.
Reference substance:
aniline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
73
Sampling time:
28 d
Details on results:
The biodegradation was 18% at day 4 and increased in a dose-dependent manner up to 73% degradation at day 28. The pass-level of 60% was thus reached within 28 days, although the 10-day window criterion was not met. However, since the test substance is a mixture of structure similar compounds the criterion of the ten days window was not applied (as in accordance with the OECD Guidelines for the testing of chemicals, laid down in the revised introduction to the OECD Guidelines for testing of chemicals, section 3; Part 1, Principles and strategies related to the testing of degradation of organic compounds, adopted 23 March 2006). For more details on the test results, see ‘Any other information on results incl. tables’.
Results with reference substance:
The biodegradation of the reference substance after 14 days was 83% (CO2/ThCO2).

INHIBITION CONTROL

The biodegradation degree of the inhibition control (CO2/ThCO2) was 62% after 14 days.

Table: Degree of Biodegradation; [%CO2/ThCO2]

Test duration [days]

RS

IH

TS1

TS2

TS mv

0

0

0

0

0

0

4

33

31

21

14

18

7

58

48

32

27

30

11

77

57

41

35

38

14

83

62

51

40

46

18

87

68

59

55

57

22

89

71

64

64

64

25

91

74

69

69

69

28

91

77

72

74

73

Theoretical Carbon dioxide [mg/test assay] : TS: 110.0, IH: 220.7, TS1: 111.0, TS2: 111.5

[%CO2/ThCO2]= CO2 amount at the sampling day/ Theoretical CO2 amount in the test assay.

Table: Measurement of total inorganic carbon Measured data: TIC [mg/L]

Day

 

BC

BC1

BC2

RS

IH

TS1

TS2

 

 

NaOH

 

 

 

 

 

 

0

a

0.6

-

-

-

-

-

-

 

b

0.7

 

 

 

 

 

 

4

a

1.1

26.2

24.7

124

211

89.2

68.6

 

b

0.8

26.5

24.2

125

214

86.7

69.3

7

a

0.6

17.6

17.5

90.4

122

53.4

57.2

 

b

0.9

18.3

17.4

92.5

120

53.3

56.3

11

a

0.6

22.8

20.3

78.9

78.1

47.6

45.6

 

b

0.7

22.2

19.8

79.5

76.1

46.9

45.3

14

a

1

12.2

11.2

30.3

40

42.7

25.9

 

b

0.8

12

11.2

30.2

39.4

42

25.6

18

a

0.8

13.2

12.6

24.3

46.4

36.2

59.4

 

b

0.9

12.8

12.7

24.1

46.1

36

58.7

22

a

0.3

10.2

12.5

17.8

28.1

27.4

38.6

 

b

0

10.3

12

17.6

28.5

28.5

37.9

25

a

0.3

5.8

5.3

11.5

26.1

18.9

22.3

 

b

0.4

5.6

5.4

11.8

26.4

18.7

22.3

28

a

0.5

5.9

5.4

9.1

17.2

12.6

15.8

 

b

0.5

5.9

5.3

8.9

17.3

13

16.2

flask 1

a

 

8.6

7.6

6.2

16.9

9.1

10.1

29

b

 

8.3

7.7

6.2

16.8

9.2

10.1

flask 2

a

 

3

3.1

2.9

3.2

4.2

4.5

29

b

 

3.3

3.1

2.6

3

3.6

4.7

The NaOH blank value is determined on filling the absorption vessels. The measured values, for instance applies on day 0 for the first and the second sampling. The NaOH blank value was subtracted from each test vessel.

a/b = single values of TIC-measurement

BC= blank control assay, RS= reference substance assay, IH= assay of inhibition control, TS= test substance assays

Table: Produced carbon dioxide amount in the test vessels

Duration of exposure [days] / [mg CO2/test vessel]

BC mv

RS

IH

TS1

TS2

RS (net)

IH (net)

TS1 (net)

TS2 (net)

4

9.1

45.5

77.7

32

25.1

36.4

68.6

22.9

16

7

6.3

33.3

44.2

19.3

20.6

63.4

106.5

35.9

30.3

11

7.5

28.7

27.9

17

16.3

84.6

126.9

45.4

39.1

14

4

10.8

14.3

15.3

9.2

91.4

137.2

56.7

44.3

18

4.5

8.6

16.7

13

21.4

95.5

149.4

65.2

61.2

22

3.8

6.2

10.1

9.9

13.7

97.9

155.7

71.3

71.1

25

1.7

4

9.3

6.6

7.9

100.2

163.3

76.2

77.3

28

2

3.2

6.3

4.6

5.8

100.6

170.8

79.5

82.4

29

3.8

3

7

4.5

5.1

 

 

 

 

 Net = mg CO2 added up after subtraction of the mean value of the blank controls.

 

 Table: Measurement of dissolved organic carbon (measured values [mg/L], determination of DOC after centrifugation)

 

 

BC1

BC2

BC mv

RS

IH

TS1

TS2

TS mv

At begin of exposure

a

0.3

0.3

0.4

19.1

38.8

19.2

19.7

 

b

0.6

0.5

19.3

38.8

19.9

19.5

At the end of exposure

a

0.9

0.7

0.8

1

5.5

5.4

3.9

b

1

0.6

1.1

5.4

5.5

4.1

Degradation of DOC [%]:

98

88

76

83

80

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable

Description of key information

The substance is readily biodegradable, as observed in a readily biodegradability test according to OECD TG 301B.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The biodegradation potential of the test substance was determined in a CO2 -Evolution Test (OECD guideline 301B). In this study 20 mg/L (TOC concentration) of the test substance was inoculated with non pre-adapted domestic activated sludge for 28 days under aerobic conditions. The biologically produced carbon dioxide was trapped and measured as indication of biodegradation. In addition, blank values, biodegradation of the reference substance aniline, and inhibitory effects were determined. Biodegradation of the reference substance (CO2/ThCO2) was 83% after 14 days. Biodegradation degree of the inhibition control (CO2/ThCO2) was 62% after 14 days. The test substance was biodegraded (CO2/ThCO2) for 73% after 28 days. The pass level of 60% degradation was reached after 22 days (64%), but the 10-day window criterion was not met. However, since the test substance is a mixture of structural similar compounds the criterion of the ten days window was not applied. This evaluation is in accordance with the OECD Guidelines for the testing of chemicals, laid down in the revised introduction to the OECD Guidelines for testing of chemicals, section 3; Part 1, Principles and strategies related to the testing of degradation of organic compounds, adopted 23 March 2006. Based on these findings, the test substance is classified as readily biodegradable.