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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
Temperature ranged from 17.7-24.2 degrees C. The pH of the sodium acetate control was not measured after 14 days. The amount of K2HPO4 in the nutrient solution was 21.7g. None of these deviations are thought to have influenced the results.
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Mitsubishi-Kagaku Foods Corporation, Batch # 2828911A
- Expiration date of the lot/batch: Aug. 27, 2004

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature
- Solubility and stability of the test substance in the solvent/vehicle: >= 10 mg/L

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Final preparation of a solid: The test substance was dissolved in 1000 mL of demineralized water to make a stock solution. From this solution, final solutions of 2.5 and 5.0 mg ThOD/L were made.

FORM AS APPLIED IN THE TEST (if different from that of starting material): Solution

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Oxidation ditch in Hazerswoude, the Netherlands
- Storage conditions: Aerated until use.
- Storage length: 5 days
- Concentration of sludge: 5 mL/L
Duration of test (contact time):
28 d
Initial conc.:
1.38 mg/L
Based on:
test mat.
Initial conc.:
2.77 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: potassium dihydrogen phosphate 8.5 mg/L, dipotassium hydrogen phosphate 21.7 mg/L, disodium monohydrogen phosphate heptahydrate 33.4 mg/L, ammonium chloride 0.5 mg/L, magnesium sulphate heptahydrate 22.5 mg/L, calcium chloride dihydrate 36.4 mg/L, iron (III) chloride hexahydrate 0.25 mg/L
- Test temperature: 17.7-24.2 degrees C
- pH: 6.2-7.3
- Aeration of dilution water: yes
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 293 ml BOD bottles
- Number of culture flasks/concentration: 16
- Method used to create aerobic conditions: aeration of mineral medium
- Measuring equipment: oxygen electrode
- Test performed in closed vessels due to significant volatility of test substance: yes


SAMPLING
- Sampling frequency: Days 0, 7, 14, 21, and 28
- Sampling method: oxygen electrode

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

STATISTICAL METHODS: Average oxygen consumption and standard deviations were calculated.
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
69
Sampling time:
21 d
Remarks on result:
other:
Remarks:
1.38 mg/L test substance
Key result
Parameter:
% degradation (O2 consumption)
Value:
64
Sampling time:
21 d
Remarks on result:
other:
Remarks:
2.77 mg/L test substance
Details on results:
Inoculum blanks showed no more than 1.50 mg O2/L degradation. The inoculum activity control showed complete biodegradation. The toxicity control showed 38-70% degradation, and thus was vallid.
Key result
Parameter:
BOD5
Value:
1.08 g O2/g test mat.
Remarks on result:
other:
Remarks:
1.38 mg/L test concentration
Key result
Parameter:
BOD5
Value:
1.04 g O2/g test mat.
Remarks on result:
other:
Remarks:
2.77 mg/L test concentration
Results with reference substance:
The reference substance results were valid with over 60% degradation in 10 days.

Percent Biodegradation Based on the ThOD/COD (Average)

Initial Concentration Test Substance

Day 0

Day 7

Day 14

Day 21

Day 28

1.38 mg/L

0

63

67

69

60

2.77 mg/L

0

54

63

64

57

Sodium acetate 4.0 mg/L

0

69

78

n.d.

n.d.

2.77 mg/L and 4.0 mg/L sodium acetate

0

61

70

n.d.

n.d.

n.d. – not determined

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance was 64-69% biodegraded in 28 days and met the 10-day window requirement and thus is readily biodegradable.
Executive summary:

The test substance LMD was tested for biodegradability in a 28-day closed bottle test using concentrations of 1.38 and 2.77 mg/L. The results of the toxicity controls, reference substance, inoculum controls, and incolum activity controls were valid. The test substance was 64-69% degraded in 28 days and met the 10-day window requirement. The test substance is therefore readily biodegradable.

Description of key information

The substance is readily biodegradible according to OECD 301D.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information