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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
experimental data of read across substances
Justification for type of information:
Data for the target chemical is summarized based on the structurally similar read across chemicals
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
WoE report is based on three biodegradation studies as-
1., 2. and 3.
GLP compliance:
not specified
Oxygen conditions:
not specified
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):
28 d
Initial conc.:
4 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
1., 2. and 3.
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
Parameter:
% degradation (O2 consumption)
Value:
97.22
Sampling time:
28 d
Remarks on result:
other: 1. Other details not known
Parameter:
% degradation (O2 consumption)
Value:
75
Sampling time:
28 d
Remarks on result:
other: 2. Other details not known
Parameter:
% degradation (O2 consumption)
Value:
82.14
Sampling time:
28 d
Remarks on result:
other: 3. Other details not known
Details on results:
1. 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 BOD28 value of test chemical was observed to be 1.05 mgO2/mg. ThOD was determined by calculation as 1.08 mgO2/mg. %Degradation was calculated using the values of BOD and ThOD for test item and was determined to be 97.22% at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.

2.The oxygen consumed by the test systems was corrected for oxygen consumption occurring in the blank test systems. The BODValues (mgO2/mg) and percent biodegradation results for each test system arereported in Tables 2 and 3, respectively. The BOD28 value of test chemical was observed to be 0.9 mgO2/mg. ThOD was determined by calculation as 1.2 mgO2/mg. % Degradation was calculated using the values of BOD and ThOD for test item and was found to be 75% at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.

3. 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 BOD28 value of test chemical was observed to be 1.15 mgO2/mg. ThOD was determined by calculation as 1.4 mgO2/mg. % Degradation was calculated using the values of BOD and ThOD for test item and was determined to be 82.14% at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 78.31%. 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:
1. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.

2.The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.

3. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 78.31%. 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.

1.

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

 

No. of Days

Inoculum Blank

(Control)

Test Suspension

Procedure Control

(Reference Item)

0

6.6

6.3

6.5

7

6.3

4.7

3.6

14

6

2.4

1.2

21

5.7

1.2

0.8

28

5.4

0.9

0.2

TABLE 2: BOD Values (mg O2/mg)

 

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0

0

7

0.32

0.65

14

0.82

1.17

21

1.05

1.2

28

1.05

1.27

 

TABLE 3: PERCENT BIODEGRDATION RESULTS

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0%

0%

7

29.62%

39.15%

14

75.92%

70.48%

21

97.22%

72.28%

28

97.22%

76.5%

 

Table 4: BOD28, THOD AND % BIODEGRADATION VALUES

 

Method details

BOD28(mgO2/mg)

ThOD (mgO2/mg)

%Biodegradation

Test Item

1.05

1.08

97.22

Reference Item

1.27

1.66

76.5

2.

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

 

No. of Days

Inoculum Blank

(Control)

Test Suspension

Procedure Control

(Reference Item)

0

6.6

6.5

6.5

7

6.3

4.1

3.6

14

6

3.5

1.2

21

5.7

2.3

0.8

28

5.4

1.7

0.2

TABLE 2: BOD Values (mg O2/mg)

 

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0

0

7

0.52

0.65

14

0.6

1.17

21

0.82

1.2

28

0.9

1.27

 

TABLE 3: PERCENT BIODEGRDATION RESULTS

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0%

0%

7

43.33%

39.15%

14

50%

70.48%

21

68.33%

72.28 %

28

75 %

76.5 %

 

Table 4: BOD28, THOD AND % BIODEGRADATION VALUES

 

Method details

BOD42(mgO2/mg)

ThOD (mgO2/mg)

%Biodegradation

Test Item

0.9

1.2

75

Reference Item

1.27

1.66

76.5

3.

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

No. of Days

Inoculum Blank

(Control)

Test Suspension

Procedure Control

(Reference Item)

0

7.1

7

7.1

7

6.7

4.7

3.7

14

6.5

3.4

2.6

21

6.2

1.8

1.1

28

5.9

1.2

0.7

TABLE 2: BOD Values (mg O2/mg)

 

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0

0

7

0.45

0.75

14

0.75

0.98

21

1.07

1.27

28

1.15

1.3

 

TABLE 3: PERCENT BIODEGRDATION RESULTS

No. of Days

Test Suspension

Procedure Control

(Reference Item)

0

0%

0%

7

32.14%

45.18%

14

53.57%

59.03%

21

76.42%

76.5%

28

82.14%

78.31%

 

Table 4: BOD28, THOD AND % BIODEGRADATION VALUES

 

Method details

BOD28(mgO2/mg)

ThOD (mgO2/mg)

%Biodegradation

Test Item

1.15

1.4

82.14

Reference Item

1.3

1.66

78.31

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be ranges from 75 to 97.22%, respectively. Thus, based on this, it can be concluded that the test chemical is readily biodegradable in water.
Executive summary:

Data available for the test chemical has been reviewed to determine the biodegradability in water. The studies are as mentioned below:

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. 1 polyseed capsule were 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. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/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 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.The BOD28 value of test chemical was observed to be 1.05 mgO2/mg. ThOD was calculated as 1.08 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 97.22%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature,

In an another study, biodegradation experiment was conducted for 28-days using the Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed using the same procedure as mentioned above. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of was observed to be 0.9 mgO2/mg. ThOD was calculated as 1.20 mgO /mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle Test was observed to be 75%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

For the test chemical, additional 28-days Closed Bottle test following the OECD guideline 301 D was carried out for determining the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C using the same procedure as that mentioned above in the other experiments. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 78.31%. 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 BOD28 value of test chemical was observed to be 1.15 mgO2/mg. ThOD was calculated as 1.4 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 82.14%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be ranges from 75 to 97.22%, respectively. Thus, based on this, it can be concluded that the test chemical is readily biodegradable in water.

Description of key information

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be ranges from 75 to 97.22%, respectively. Thus, based on this, it can be concluded that the test chemical is readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Data available for the test chemical has been reviewed to determine the biodegradability in water. The studies are as mentioned below:

 

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. 1 polyseed capsule were 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. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/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 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid.The BOD28 value of test chemical was observed to be 1.05 mgO2/mg. ThOD was calculated as 1.08 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 97.22%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature,

 

In an another study, biodegradation experiment was conducted for 28-days using the Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed using the same procedure as mentioned above. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 76.5%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of was observed to be 0.9 mgO2/mg. ThOD was calculated as 1.20 mgO /mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle Test was observed to be 75%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

 

For the test chemical, additional 28-days Closed Bottle test following the OECD guideline 301 D was carried out for determining the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C using the same procedure as that mentioned above in the other experiments. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 78.31%. 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 BOD28 value of test chemical was observed to be 1.15 mgO2/mg. ThOD was calculated as 1.4 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 82.14%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

 

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the percentage degradation of the test chemical can be expected to be ranges from 75 to 97.22%, respectively. Thus, based on this, it can be concluded that the test chemical is readily biodegradable in water.