Disodium 2-(2,4,5,7-tetraiodo-6-oxido-3-oxoxanthen-9-yl)benzoate

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result performed using standard OECD test guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

other: Mixed Inoculum

Details on inoculum:

Domestic waste water, surface soil and soil samples from polluted sites receiving predominantly domestic waste was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions. This gave the bacterial count as10e7 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.:

100 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 Respirometer BOD Sensor System (Code: F102B0133; non-automatic pressure measurement sensor system) and Respirometric incubator (FOC 120i)) by VELP Scientifica.

CONTROL AND BLANK SYSTEM
- Inoculum blank: it contains only test inoculum
- Procedure control: contains reference compound and inoculum

Reference substance:

benzoic acid, sodium salt

Remarks:

100 mg/l

Parameter:

other: BOD & ThOD

Value:

8.18

Sampling time:

28 d

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 are reported in Tables. The BOD28 value of test chemical was observed to be 0.058 mgO2/mg. ThoD was determined by calculation as 0.709 mgO2/mg. % Degradation was calculated using the values of BOD and ThOD for test chemical and was found to be 8.18%. The % degradation of procedure control (reference chemical) was also calculated using BOD & ThOD and was found to be 77.36%. The mean BOD values (mg O2/l) in control on 28th day was 28.2 mg O2/l, thereby fulfilling the control validity criteria (i.e., The oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). The percentage degradation of reference substance (Sodium benzoate) has reached the pass levels (60% of its ThOD) by Day 14. Thus, fulfilling the validity criteria of the study.

Results with reference substance:

ThOD, BOD28 and % Degradation of reference substance calculated using the formula given in OECD guideline 301 F Manometric Respirometry Test, are summarized in Table 4.

TABLE 1: MEAN RESPIROMETRIC VALUES(oxygen consumed mg O2/l)

No. of Days	Inoculum Blank (Control)	Test Suspension	Procedure Control (Reference Item)
1	11.4	11.2	26.5
2	15.6	15.3	26.5
3	20	19.7	23
4	24.1	26	40
5	24.3	26.5	70.5
6	26.3	28.2	100.5
7	26.2	28.7	108
8	26.5	29.6	120.5
9	-	-	-
10	-	-	-
11	26.8	30.6	127
12	26.2	29.9	133
13	26.8	30.6	142.5
14	-	-	-
15	27.1	30.9	144.5
16	27.1	31.5	146.5
17	-	-	-
18	27.1	32	150
19	27.3	32	152
20	27.6	32.6	154.5
21	27.1	31.7	154.5
22	27.6	32.6	155.5
23	27.6	33.1	155
24	27.9	33.1	156.5
25	-	-	-
26	27.6	33.1	157
27	28.2	34	158
28	28.2	34	157

 

TABLE 2: BOD values (mgO₂/mg)

No. of Days	Test Suspension	Procedure Control (Reference Item)
1	-0.002	0.151
2	-0.003	0.109
3	-0.003	0.03
4	0.019	0.159
5	0.022	0.462
6	0.019	0.742
7	0.025	0.818
8	0.031	0.94
9	-	-
10	-	-
11	0.038	1.002
12	0.037	1.068
13	0.038	1.157
14	-	-
15	0.038	1.174
16	0.044	1.194
17	-	-
18	0.049	1.229
19	0.047	1.247
20	0.05	1.269
21	0.046	1.274
22	0.05	1.279
23	0.055	1.274
24	0.052	1.286
25	-	-
26	0.055	1.294
27	0.058	1.298
28	0.058	1.288

 

TABLE 3: PERCENT BIODEGRDATION RESULTS

No. of Days	Test Suspension	Procedure Control (Reference Item)
1	-0.28	9.07
2	-0.42	6.55
3	-0.42	1.80
4	2.68	9.55
5	3.10	27.75
6	2.68	44.56
7	3.53	49.13
8	4.37	56.46
9	-	-
10	-	-
11	5.36	60.18
12	5.22	64.14
13	5.36	69.49
14	-	-
15	5.36	70.51
16	6.21	71.71
17	-	-
18	6.91	73.81
19	6.63	74.89
20	7.05	76.22
21	6.49	76.52
22	7.05	76.82
23	7.76	76.52
24	7.33	77.24
25	-	-
26	7.76	77.72
27	8.18	77.96
28	8.18	77.36

 

Table 4: BOD28, THOD AND % BIODEGRADATION VALUES

Method details	BOD28(mgO2/mg)	ThOD (mgO2/mg)	% Biodegradation
Test Item	0.058 mgO2/mg	0.709 mgO2/mg	8.18 %
Reference Item	1.288 mgO2/mg	1.665 mgO2/mg	77.36 %

 

TABLE 5: pH OF RESPIROMETER FLASK

Respirometer Flask	pH on 0^thDay	pH on 28^thDay
Inoculum Blank(Control)         B1	7.4	7.7
B2	7.4	7.7
Test Suspension B1	7.5	7.8
B2	7.5	7.6
Procedure Control B1	7.5	7.6
B2	7.5	7.7

 

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test chemical undergoes 8.18 % biodegradation after 28 days in the test condition. Thus, the test chemical can be considered as not readily biodegradable.

Executive summary:

28-days Manometric respirometry test was conducted following the OECD guideline 301F to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20 ± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions. This gave the bacterial count as 107to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 100mg/L, while that of inoculum was 10ml/l. 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 chemical and reference chemical. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 77.36%. The mean BOD values (mg O2/l) in control on 28th day was 28.2 mg O2/l, thereby fulfilling the control validity criteria (i.e., the oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 60% after 14 days. The activity of the inoculums is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.058 mgO2/mg. ThOD was calculated as 0.709 mgO2/mg. Accordingly, the % degradation of the test chemical after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 8.18%. Thus, the test chemical can be considered as not readily biodegradable.

Description of key information

28-days Manometric respirometry test was conducted following the OECD guideline 301F to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20 ± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions. This gave the bacterial count as 107to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 100mg/L, while that of inoculum was 10ml/l. 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 chemical and reference chemical. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 77.36%. The mean BOD values (mg O2/l) in control on 28th day was 28.2 mg O2/l, thereby fulfilling the control validity criteria (i.e., the oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 60% after 14 days. The activity of the inoculums is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.058 mgO2/mg. ThOD was calculated as 0.709 mgO2/mg. Accordingly, the % degradation of the test chemical after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 8.18%. Thus, the test chemical can be considered as not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

28-days Manometric respirometry test was conducted following the OECD guideline 301F to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20 ± 1°C. Mixture of domestic waste water, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions. This gave the bacterial count as 107to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 100mg/L, while that of inoculum was 10ml/l. 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 chemical and reference chemical. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was found to be 77.36%. The mean BOD values (mg O2/l) in control on 28th day was 28.2 mg O2/l, thereby fulfilling the control validity criteria (i.e., the oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 60% after 14 days. The activity of the inoculums is thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.058 mgO2/mg. ThOD was calculated as 0.709 mgO2/mg. Accordingly, the % degradation of the test chemical after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 8.18%. Thus, the test chemical can be considered as not readily biodegradable.