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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
end of May 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: study performed according to OECD guideline and GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Potassium (R)-(4-hydroxyphenyl)[(3-methoxy-1-methyl-3-oxoprop-1-enyl)amino]acetate
EC Number:
273-992-8
EC Name:
Potassium (R)-(4-hydroxyphenyl)[(3-methoxy-1-methyl-3-oxoprop-1-enyl)amino]acetate
Cas Number:
69416-61-1
Molecular formula:
C13H15NO5.K
IUPAC Name:
potassium (4-hydroxyphenyl)[(3-methoxy-1-methyl-3-oxoprop-1-en-1-yl)amino]acetate
Details on test material:
- Name of test material (as cited in study report): D(-)-p-Hydroxyphenylglycine Dane Salt(K, Methyl)
- Substance type: monoconstituent substance
- Physical state: powder
- Stability under test conditions: this is the subject of the study
- Storage condition of test material: at room temperature, protected from light

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Prior to use a sample of activated sludge from the sewage plant at Taunusstein-Bleidenstadt was washed twice with mineral nutrient solution of the CO2-Evolution-Test to eliminate organic components and carbonates from the sludge. After resolution with mineral nutrient medium the sludge was aerated by means of compressed humidified air for about four hours. Before use as inoculum for the CO2-Evolution-Test the sludge was homogenised in a "Waring Blender" at low speed for 2 minutes and then filtered through a cotton filter previously carefully rinsed with deionised water. The filtrate was used as inoculum (1% of the final volume of the test solution) on the same day of preparation.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
19.5 - 19.7 other: ca. 10 mg C/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: according to OECD guideline
- Additional substrate: no
- Solubilising agent: no
- Test temperature: 19.4 to 22.8 °C (mean 20.0°C)
- pH: not measured
- pH adjusted: no
- Aeration of dilution water: the aeration rate of the test system was controlled at 4 L/h being assured by precise flowmeters
- Continuous darkness: data not available

TEST SYSTEM
- 5-litre amber carboys served as test vessels
- Number of culture flasks/concentration: 2 (test item), 1 (sodium benzoate and toxicity control)
- Method used to create aerobic conditions: the aeration rate of the test system was controlled at 4 L/h being assured by precise flowmeters
- Test performed in closed vessels due to significant volatility of test substance: the vessels were closed with stoppers with tubing for gas inlet and outlet (gas exit line)
- Details of trap for CO2 and volatile organics if used: CO2 generated by the test item was trapped by 0.025 N Ba(OH)2 in a trap system described in the Guideline. Resting Ba(OH)2 (0.025 N) in the CO2 trap removed from the trap system was titrated with HCl (0.05 N) using phenolphthalein as an indicator.

SAMPLING
- Sampling frequency: Titrations were performed at t4d, t6d, t8d, t12d, t19d, t26d, t28d, and t29d
- Sample storage before analysis: data not available

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes
- Positive control: yes (sodium benzoate)

STATISTICAL METHODS: not applicable
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
ca. 88
Sampling time:
28 d
Remarks on result:
other: the “10-days-window” was met
Details on results:
Calculated from the organic carbon content of the test item and the measured CO2 generation, 92% of the theoretical CO2 (ThCO2) has been generated by the test item within 28 d of test period in the first culture with 69.1 mg of test item. 85% of the theoretical CO2 (ThCO2) has been generated by the test item within 28 d in the second culture with 68.3 mg of test item. The calculated mean degradation value of the test item was 88%. The “10-days-window” was met, too.

BOD5 / COD results

Results with reference substance:
The control item sodium benzoate was degraded 83% the threshold of 60% degradation being met within 8 days.

Any other information on results incl. tables

Table 1: Degradation / elimination kinetics

Type of suspension

Vessel no.

% degradation at sampling time (days)

4

6

8

12

19

26

28

29

 

Test item

1

2

11

27

69

86

88

89

92

 

 

2

2

11

19

28

61

83

83

84

 

Reference substance

3

34

56

69

73

77

80

81

83

 

Toxicity control

4

7

32

38

49

56

57

58

60

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item D(-)-p-Hydroxyphenylglycine Dane Salt(K, Methyl) should be regarded “readily biodegradable”.
Executive summary:

D(-)-p-Hydroxyphenylglycine Dane Salt(K, Methyl)was tested for biodegradability according to 'CO2-Evolution-Test' (OECD Guideline 301B, GLP). Calculated from the organic carbon content of the test item and the measured CO2generation, 92% of the theoretical CO2(ThCO2) has been generated by the test item within 28 d of test period in the first culture with 69.1 mg of test item. 85% of the theoretical CO2(ThCO2) has been generated by the test item within 28 d in the second culture with 68.3 mg of test item. The calculated mean degradation value of the test item was 88%. The “10-days-window” was met, too. Thus, the test item D(-)-p-Hydroxyphenylglycine Dane Salt(K, Methyl) should be regarded “readily biodegradable”. The total CO2-evolution of the Blank was 79 mg CO2being in the requested range of the OECD test guideline 301B. The control item sodium benzoate was degraded 83% the threshold of 60% degradation being met within 8 days. Thus, all conditions of validity were met and the test is regarded to be valid. The results obtained with the toxicity control indicate that there was no toxicity of the test item towards microorganisms at the concentration used within the test.