Disodium succinate

Biodegradation in water: screening tests

Link to relevant study record(s)

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

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Principles of method if other than guideline:

Biodegradation study was conducted according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test) for evaluating the percentage biodegradability of test chemical.

GLP compliance:

no

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:

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:

97.1

Sampling time:

28 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 BOD28 value of test chemical was observed to be 0.67 mgO2/mg. ThOD was determined by calculation as 0.69 mgO2/mg. % degradation was calculated using the values of BOD and ThOD for test item and was determined to be 97.1% 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 45.18% on 7 days & 70.48% 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 determined to be 76.5%. Degradation of Sodium Benzoate exceeds 45.18% on 7 days & 70.48% 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	6	6.2	6.4
7	5.8	4.8	3.2
14	5.5	3.4	1.2
21	5.2	2.8	0.7
28	5	2.5	0.3

TABLE 2: BOD Values (mg O2/mg)

 

No. of Days	Test Suspension	Procedure Control (Reference Item)
0	0	0
7	0.3	0.75
14	0.57	1.17
21	0.65	1.23
28	0.67	1.27

 

TABLE 3: PERCENT BIODEGRDATION RESULTS

No. of Days	Test Suspension	Procedure Control (Reference Item)
0	0%	0%
7	43.47%	45.18%
14	82.6%	70.48%
21	94.2%	74.1%
28	97.1%	76.5%

 

Table 4: BOD28, THOD AND % BIODEGRADATION VALUES

 

Method details	BOD28(mgO2/mg)	ThOD (mgO2/mg)	%Biodegradation
Test Item	0.67	0.69	97.1
Reference Item	1.27	1.66	76.5

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item undergoes 97.1% biodegradation after 28 days in the test condition. Thus, the test item was considered to be readily biodegradable.

Executive summary:

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. 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 45.18% 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 0.67 mgO2/mg. ThOD was calculated as 0.69 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 97.1%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Description of key information

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (Experimental study report, 2018). 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. 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 45.18% 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 0.67 mgO2/mg. ThOD was calculated as 0.69 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 97.1%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Various experimental key and supporting studies of the test chemical were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from study report (2018),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. 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 45.18% 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 0.67 mgO2/mg. ThOD was calculated as 0.69 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 97.1%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

 

For the test chemical, the Biodegradation experiment was carried out for determining biodegradability of test chemical following the OECD Guideline 301 C "Ready Biodegradability: Modified MITI Test (I)" under aerobic conditions (from authoritative database, handbook and secondary source, 2018). In this experiment, non adapted activated sludge was used as test inoculum for the study at 30 mg/L concentration. Aniline was used as a reference substance for the study.The initial concentration of test chemical was 100 mg/L. Biodegradation was analyzed by using three parameters namely O2 consumption (BOD), TOC removal and test material analysis by HPLC. After 14 days of incubation, percent biodegradation of test chemical was determined to be 72 % by O2 consumption (BOD) parameter 100 % by TOC removal and test material analysis by GC parameter, respectively. Therefore, it is concluded that test chemical is considered to be readily biodegradable in water.

 

On the basis of above results for test chemical, it can be concluded that the test chemical can be expected to be readily biodegradable in nature.