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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental result using OECD guidelines.
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: Mixed inoculum
Details on inoculum:
Mixed Inoculum Preparation:Polyseed were used for this study. 1 polyseed capsule was added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 10E7 to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism.

Duration of test (contact time):
42 d
Initial conc.:
4 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: OECD mineral medium was used for the study
- Test temperature: 20°C
- Continuous darkness: Yes
- Other: The water used in this study is deionized water.

TEST SYSTEM
- Culturing apparatus: The apparatus used in this study is BOD bottles; with glass stoppers (125 ml), BOD incubator & oxygen electrode and meter.

CONTROL AND BLANK SYSTEM
- Inoculum blank: it contains only test inoculum
- Procedure control: contains reference compound and inoculum
Reference substance:
other: Sodium Benzoate
Key result
Parameter:
% degradation (O2 consumption)
Value:
46.92
Sampling time:
42 d
Remarks on result:
other: Other details not known
Details on results:
The oxygen consumed by the test systems was corrected for oxygen consumption occurring in the blank test systems.The BOD Values (mgO2/mg) and percent biodegradation results for each test system arereported in Tables 2 and 3, respectively. The BOD42 value of test chemical was observed to be 1.07 mgO2/mg. ThOD was determined by calculation as 2.28 mgO2/mg. % Degradation was calculated using the values of BOD and ThOD for test item and was found to be 46.92% at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 72.28%. Degradation of Sodium Benzoate exceeds 45.18 % on 7 days & 59.03% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.
Results with reference substance:
The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 72.28%. Degradation of Sodium Benzoate exceeds 45.18 % on 7 days & 59.03% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.

Table 1: D.O Values (mg/L)

No. of days

Inoculum Blank (Control)

 Test Suspension

Procedure Control

(Reference Item)

0

7.1

6.9

7.1

7

6.7

5

3.7

14

6.5

4.6

2.6

21

6.2

3.4

1.1

28

5.9

2.2

0.7

35

5.3

1

0.4

42

5.1

0.6

0.3

 

Table 2: BOD values (mgO2/mg)

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0

0

7

0.38

0.75

14

0.43

0.98

21

0.65

1.27

28

0.87

1.3

35

1.02

1.22

42

1.07

1.2

 

Table 3: Percent biodegradation results

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0%

0%

7

16.66%

45.18%

14

18.85%

59.03%

21

28.5%

76.5%

28

38.15%

78.31%

35

44.73%

73.49%

42

46.92%

72.28%

 

%

%

 

Table 4: BOD42, THOD AND % BIODEGRADATION VALUES

Method details

BOD42 (mgO2/mg)

ThOD (mgO2/mg)

% Biodegradation

Test Item

1.07

2.28

46.92

Reference Item

1.2

1.66

72.28

Validity criteria fulfilled:
yes
Interpretation of results:
other: ultimate inherently biodegradable
Conclusions:
The test item undergoes 46.92 % biodegradation after 42 days in the test condition. Thus, the test item was considered to be ultimate inherently biodegradable.
Executive summary:

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as inoculum at concentration 10E7 to 10E8 CFU/ml. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32ml/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 72.28 %. Degradation of Sodium Benzoate exceeds 45.18 % on 7 days & 59.03% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD42 value of test material was observed to be 1.07 mgO2/mg. ThOD was determined by calculation as 2.28 mgO2/mg. The test item undergoes 46.92 % biodegradation after 42 days in the test condition. Thus, the test item was considered to be ultimate inherently biodegradable.

Description of key information

The test item  undergoes 46.92 % biodegradation after 42 days in the test condition. Thus, the test item was considered to be ultimate inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable
Type of water:
freshwater

Additional information

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as inoculum at concentration 10E7 to 10E8 CFU/ml. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32ml/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 72.28 %. Degradation of Sodium Benzoate exceeds 45.18 % on 7 days & 59.03% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD42 value of 7-(diethylamino)-4-methyl-2-benzopyrone(CAS No.91-44-1) was observed to be 1.07 mgO2/mg. ThOD was determined by calculation as 2.28 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 46.92 %. Based on the results, the test item under the test conditions was considered to be ultimate inherently biodegradable in nature.