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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-02-08
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with abridged report

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report date:
2002

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
(vers. 1992)
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Zinc bis[12-hydroxyoctadecanoate]
EC Number:
252-669-5
EC Name:
Zinc bis[12-hydroxyoctadecanoate]
Cas Number:
35674-68-1
Molecular formula:
C18H36O3.1/2Zn
IUPAC Name:
zinc(2+) ion bis(12-hydroxyoctadecanoate)
Test material form:
other: solid
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): municipal sewage treatment plant (67435 Neustadt Wstr., Germany), aeration tank, sample from 2002-02-06
- Pretreatment: activated sludge was aerated continuously and wash with drinking water and OECD-media
- Concentration of sludge: the dry residue was determined to be 7.28 g suspended solids/L, the concentration for testing was 25 mg solids/L
Duration of test (contact time):
29 d
Initial test substance concentration
Initial conc.:
20 mg/L
Based on:
other: calculated organic carbon content
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium acc. to OECD
- Solubilising agent (type and concentration if used): none
- Test temperature: room temperature (20 +/- 1°C)
- pH: no data
- pH adjusted: no data

- Suspended solids concentration: 25 mg solids/L
- Test vessels: "Woulffe'sche bottles" 5 L volume
- Test volume: 3000 mL each
- Continuous darkness: no data

TEST SYSTEM
- Sample preparation: the org. carbon content was calculated to be 68.7 %
- Culturing apparatus: aeration with clean, moistened CO2-free air during the test
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration with clean, moistened CO2-free air for 24 h before testing
- Measuring equipment: IC measurement of the emitted CO2 wit a TOC 5050A;
- Test performed in closed vessels due to significant volatility of test substance: no data
- Test performed in open system: no data
- Details of trap for CO2 and volatile organics if used: discharched air was trapped in 0.25 M NaOH solution (one trap followed by a second one)

SAMPLING
- Sampling frequency: at day 2, 4, 6, 8, 10, 13, 17, 21, 28, and 29 of the study
- Sampling method: for the IC measurement 0.5 or 1 ml solution were sampled from the first of the two NaOH traps; on day 29 both bottles were sampled and the IC results were summed up

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes, without inoculum
- Toxicity control: testsubstance + aniline


STATISTICAL METHODS: according to guideline
Reference substance
Reference substance:
aniline

Results and discussion

Preliminary study:
no data
Test performance:
No unusual observations during test reported.
% Degradationopen allclose all
Parameter:
% degradation (CO2 evolution)
Value:
14.5
Sampling time:
4 d
Parameter:
% degradation (CO2 evolution)
Value:
53.5
Sampling time:
13 d
Remarks on result:
other: end of 10 d window
Parameter:
% degradation (CO2 evolution)
Value:
71.4
Sampling time:
28 d
Parameter:
% degradation (CO2 evolution)
Value:
72
Sampling time:
29 d
Details on results:
- The 10 day window begins at day 3 (graphically determined). At day 13 53 % was degraded. At the end of the test 72 % was degraded. Thus, the 60 % pass level within the 10 day window was failed.
- Abiotic degration was 4 %.

- Validity: The test is considered valid, as
- the difference of extremes of replicate values of the removal of the test item at the end of the test is less than 20%,
- the percentage degradation of the reference item has reached the pass level of 60% by day 14,
- the total CO2 production of the blind trial was 25 mg CO2/L (mean value)
- Toxicity: If the total degardation in the toxicity test is below 25 %, the test substance is regared as toxic. In this study the total degradation was 49 % in in the toxicity test. However, since the theoretical degradation (mean value of reference and test approach) is 75%, an inhibition of degradation by the test substance was assumed.

BOD5 / COD results

Results with reference substance:
The reference substance aniline was degraded to 72 % within 10 days.

Any other information on results incl. tables

Table 1: Emitted carbon in mg/L

Day

Blind1

Blind2

Refer.

Test 1

Test 2

abiot.

Toxicity

2

1.50

1.66

1.30

2.64

1.65

1.26

0.84

4

2.42

2.53

10.93

5.81

5.28

1.00

4.66

6

2.06

1.77

12.49

8.10

8.23

0.73

10.24

8

2.64

2.80

15.47

11.66

10.65

0.36

15.22

10

3.02

3.28

17.81

14.07

12.77

0.48

17.64

13

4.26

4.88

20.26

17.16

14.58

1.19

21.67

17

4.28

5.00

21.50

19.55

18.49

0.98

24.20

21

4.34

5.11

21.10

19.51

19.30

1.53

24.77

28

4.11

4.77

21.05

20.04

19.02

0.86

25.93

29

6.25

7.42

22.78

22.56

21.53

0.79

27.07

 

Table 2: Degradation in %

Day

Refer.

Test 1

Test 2

Mean

abiot.

Toxicity

2

-1.4

5.0

0.3

2.7

6.0

-1.8

4

41.5

15.7

13.3

14.5

4.8

5.3

6

52.0

29.1

30.0

29.6

3.5

20.1

8

62.6

42.2

37.7

39.9

1.7

30.2

10

72.0

51.5

45.7

48.6

2.3

35.0

13

77.1

59.4

47.6

53.5

5.7

41.3

17

82.9

70.3

65.8

68.0

4.7

47.2

21

80.5

69.7

69.3

69.5

7.3

48.4

28

81.6

73.6

69.3

71.4

4.1

51.9

29

78.3

74.2

69.8

72.0

3.7

48.9

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
see above, "Detail on results" for details
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
Altogether, 71.4% of zinc-12-hydroxystearate was biodegraded after 28 days as determined in the OECD 301B test with 14.5 % after 4 days and 53.5% after 13 days. Zinc-12-hydroxystearate is readily biodegradable as the 60% level was passed within 28 days but failed the 10 day window criteria.