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Environmental fate & pathways

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:
21 Jul - 18 Aug 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Secondary effluent from a domestic sewage treatment plant (Kläranlage Odenthal, Germany). Date of collection: 16 Jul 1999
- Laboratory culture: no
- Pretreatment: separation of coarse particles by filtration
- Storage length: 5 days (aerated)
- Concentration of effluents in reaction mixture: 5 mL/L
Duration of test (contact time):
28 d
Initial conc.:
2.9 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 20 ± 1 °C
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2 replicates

SAMPLING
- Sampling frequency: On day 7, 14, 21 and 28
- Sampling method: O2 depletion in test vessels was measured

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 replicates
- Abiotic sterile control: no
- Toxicity control: yes, 2 replicates
- Other: reference substance: 2 replicates
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
5
Sampling time:
28 d
Details on results:
5% degradation after 28 d, 60% pass level and 10-day window were not met.
Results with reference substance:
80% after 28 d, 60% pass level was reached.

Table 1: % degradation of the test substance, reference substance and in the toxicity control

day

% degradation test substance

% degradation reference substance

% degradation toxicity control

1

2

Mean

1

2

Mean

1

2

Mean

7

1

2

2

67

70

69

29

30

30

14

1

2

2

79

68

74

33

34

34

21

1

3

2

83

83

83

34

34

34

28

6

3

5

80

80

80

33

33

33

The toxicity control attained 34% degradation after 14 d indicating that the test substance is not inhibitory to the inoculum (degradation > 25% based on ThOD).

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Under the used test conditions 5% degradation of the test substance (based on O2 consumption) was observed after 28 d (EU Method C.4-E). Hence, the substance has to be considered as not readily biodegradable according to OECD criteria.
Executive summary:

One experimental study is available investigating the ready biodegradability of the test substance (1999). The study was performed according to the EU Method C.4-E (GLP). Secondary effluent from a domestic sewage treatment plant was used as inoculum. After 28 d 5% degradation of the test substance was recorded based on O2-consumption. Thus, the test substance is not readily biodegradable according to the OECD criteria. A toxicity control containing both, reference substance and test substance did not indicate inhibitory effects to the inoculum (34% degradation after 14 d). All validity criteria were met.

Description of key information

Under the used test conditions 5% degradation of the test substance (based on O2 consumption) was observed after 28 d (EU Method C.4-E). Hence, the substance has to be considered as not readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

One experimental study is available investigating the ready biodegradability of the test substance (1999). The study was performed according to the EU Method C.4-E (GLP). Secondary effluent from a domestic sewage treatment plant was used as inoculum. After 28 d 5% degradation of the test substance was recorded based on O2-consumption. Thus, the test substance is not readily biodegradable according to the OECD criteria. A toxicity control containing both, reference substance and test substance did not indicate inhibitory effects to the inoculum (34% degradation after 14 d). All validity criteria were met.