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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
From 12th of February to 11th of March 1992.
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Version / remarks:
An update has been made to the OECD Guideline since the publication of the report.
Principles of method if other than guideline:
Modified MITI Method (II)
GLP compliance:
not specified
Test material information:
Composition 1
Specific details on test material used for the study:
Test material: CYDI ((1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide)
Description: Off-white powder
Storage: In original container at room temperature
Molecular formula: C5H4N4O2
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
A mixed population of activated sewage sludge microorganisms.
Activated sewage was prepared by sampling 10 different sites around the UK in accordance with 0ECD Guideline No. 302C.
Duration of test (contact time):
28 d
Initial conc.:
ca. 30 mg/L
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Inoculum: A mixed population of activated sewage sludge microorganisms.
Source: Activated sewage was prepared by sampling 10 different sites around the UK in accordance with 0ECD Guideline No. 302C.
Preparation: The mixed sludge was fed faily with a 0.1% synthetic sewage and maintained on a constant aeration at 25 ± 1°C.
Usage rate: Equivalent to 100 mg dry weight/L.
Reference substance: Aniline.
Duration: 28 days.
Critera: Oxygen consumption measured by direct manometer reading.
Agitation: By magnetic stirrers.
Temperature: 25 ± 1°C.
Lighting: The test was carried out in darkness.
Observations: Manometer volumes were recorded daily.
Test concentrations: Test substance: 30 mg/L
Aniline: 100 mg/L
Reference substance:
aniline
Parameter:
% degradation (O2 consumption)
Remarks on result:
other: The test substance attained negligeable biodegradation after 28 days.
Details on results:
CYDI attained negligeable degradation after 28 days calculated from oxygen uptake (% of ThOD) and so, therefore, cannot be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines.
Results with reference substance:
Aniline attained 47% biodegrada'ion after 7 days, 55% after 14 days and 64% by Day 28. However aniline attajned 66% biodegradation on Day 25 thereby conf i rming the suitability of the inoculum and culture conditions. The resulting decrease in percentage degradation is considered to be the result of experimental error.

Day

% Biodegradation

CYDI

Aniline

1

0

0

2

6

9

3

2

38

4

0

43

5

5

45

6

6

47

7

4

47

8

4

48

9

8

49

10

8

49

11

12

51

12

9

52

13

5

53

14

6

55

15

6

56

16

6

57

17

0

59

18

0

61

19

0

62

20

0

63

21

0

63

22

0

64

23

0

64

24

0

65

25

0

66

26

0

64

27

0

64

28

0

64

Validity criteria fulfilled:
not specified
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
CYDI ((1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide) attained negligeable degradation after 28 days calculated from oxygen uptake (% of ThOD) and so, therefore, cannot be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines.
Executive summary:

The inherent biodegradation of (1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide was assessed by modified MITI method (II).

(1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide) attained negligeable degradation after 28 days calculated from oxygen uptake (% of ThOD) and so, therefore, cannot be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines.

Description of key information

The inherent biodegradation of (1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide was assessed by modified MITI method (II).

(1,4,5,6-Tetrahydro-4,6-dioxopyrimidin-2-yl)cyanamide) attained negligeable degradation after 28 days calculated from oxygen uptake (% of ThOD) and so, therefore, cannot be considered as inherently biodegradable under the strict terms and conditions of the OECD Guidelines.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information