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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
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 substance.
GLP compliance:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): isopropyl 4-hydroxybenzoate
- Molecular formula : C10H12O3
- Molecular weight : 180.202 g/mol
- Smiles notation : c1(C(OC(C)C)=O)ccc(O)cc1
- InChl : 1S/C10H12O3/c1-7(2)13-10(12)8-3-5-9(11)6-4-8/h3-7,11H,1-2H3
- Substance type:Organic
- Physical state:Solid
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:
61.27
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 Isopropyl 4-hydroxybenzoate(CAS No.4191-73-5) was observed to be 1.25 mgO2/mg. ThOD was determined by calculation as 2.04 mgO2/mg. % Degradation was calculated using the values of BOD and ThOD for test item and was determine to be 61.27% at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determine 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

3.5

3.2

14

5.5

1.1

1.2

21

5.2

0.5

0.7

28

5

0.2

0.3

Table 2: BOD values (mgO2/mg)

No. of Days

Test Suspension

Procedure Control (Reference Item)

0

0

0

7

0.62

0.75

14

1.15

1.17

21

1.23

1.23

28

1.25

1.27

Table 3: Percent biodegradation results

No. of Days

Test Suspension

Procedure Control (Reference Item)

0

0%

0%

7

30.39%

45.18%

14

56.37%

70.48%

21

60.29%

74.1%

28

61.27%

76.5%

 

%

%

Table 4: BOD42, THOD AND % BIODEGRADATION VALUES

Method details

BOD28 (mgO2/mg)

ThOD (mgO2/mg)

% Biodegradation

Test Item

1.25

2.04

61.27

Reference Item

1.27

1.66

76.5

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The Isopropyl 4-hydroxybenzoate(CAS No.4191-73-5) undergoes 61.27% biodegradation after 28 days in the test condition. Thus, the test item was considered to be readily biodegradable in nature.
Executive summary:

28-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 32 ml. 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 Isopropyl 4-hydroxybenzoate(CAS No.4191-73-5) was observed to be 1.25 mgO2/mg. ThOD was determined by calculation as 2.04 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle Test was found to be 61.27%. 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 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 32 ml. 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 Isopropyl 4-hydroxybenzoate(CAS No.4191-73-5) was observed to be 1.25 mgO2/mg. ThOD was determined by calculation as 2.04 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle Test was found to be 61.27%. 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

28-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 32 ml. 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 Isopropyl 4-hydroxybenzoate(CAS No.4191-73-5) was observed to be 1.25 mgO2/mg. ThOD was determined by calculation as 2.04 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle Test was found to be 61.27%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.