Methyl phenylacetate

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 F (Ready Biodegradability: Manometric Respirometry Test)

Principles of method if other than guideline:

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

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixture of domestic waste water, surface soil and soil samples

Details on inoculum:

Mixed Inoculum Preparation (In-House): 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 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.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: BOD and ThOD

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:

other: Sodium Benzoate

Key result

Parameter:

other: BOD and ThOD

Value:

65.66

Sampling time:

28 d

Remarks on result:

other: Other details not known

Details on results:

The DO depletion and percent biodegradation results for each test system are reported. The DO depletion by the test systems was corrected for DO depletion occurring in the blank test systems.The DO depletion in the inoculum blank (control) at the end of test duration was determined to be 19.1 mgO2/l. The BOD28 value of test chemical was observed to be 1.469 mgO2/mg. ThoD was determined by calculation as 2.237 mgO2/mg. % Degradation was calculated using the values of BOD and ThOD for test substance. Accordingly, the % degradation of the test substance after 28 days of incubation at 20°C according to manometric respirometry test was determined to be 65.66 %. The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 227.4 %. The DO depletion (mg O2/l) in control on 28th day is 19.1 mg O2/l which full fills the control validity criteria (i.e., The DO depletion 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 acetate exceeds 168.29% after 7 days and 212.76 % after 14 days. The activity of the inoculum is thus verified and the test is considered as valid.

Results with reference substance:

The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 227.4 %. The DO depletion (mg O2/l) in control on 28th day is 19.1 mg O2/l which full fills the control validity criteria (i.e., The DO depletion 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 acetate exceeds 168.29% after 7 days and 212.76 % after 14 days. The activity of the inoculum is thus verified and the test is considered as valid.

TABLE 1

DO DEPLETION(Oxygen Consumed mg O2/l)

No. of Days	Control	Test Substance	Reference Substance
1	8.1	53	28
2	15.3	59	54
3	16.9	72	87
4	16.9	78.5	92
5	15.8	86.5	95
6	16.9	87	95
7	16.9	93	96
8	16.9	94.5	100
9	16.9	99.5	110
10	-	-	-
11	16.9	109	117
12	16.9	109	112
13	16.4	112.5	115
14	16.4	118	117
15	-	-	-
16	18	122.5	118
17	-	-	-
18	18.6	136.5	121
19	18.6	143	123
20	18.6	146	123
21	18.9	149	123
22	18.6	156	125
23	-	-	-
24	-	-	-
25	18.6	156	126
26	19.1	166	126
27	19.1	166	126
28	19.1	166	126

 

Table 2

BOD₂₈, Calculated ThOD and % Biodegradation Values

Method details	BOD28(mgO2/mg)	ThOD (mgO2/mg)	% Biodegradation
Test Substance	1.469 mg O2/mg	2.237 mg O2/mg	65.66 %
Reference Substance	1.069 mg O2/mg	0.470 mg O2/mg	227.4 %

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The test chemical undergoes 65.66 % biodegradation after 28 days in the test condition. Biodegradation Start on day 1 and reaches 65.66 % at the end of 28th day. Thus, the test substance can be inferred as readily biodegradable, but failing 10-day window period validity criterion according to this test. The test substance exhibited the potential for rapid degradation.

Executive summary:

28-days Manometric respirometry test 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 100 mg/L, while that of inoculum was 100 mg/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 item and reference item. The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 227.4%. The DO depletion (mg O2/l) in control on 28th day is 19.1 mg O2/l which full fills the control validity criteria (i.e., The DO depletion 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 acetate exceeds 168.29% after 7 days and 212.76 % after 14 days. The activity of the inoculum is thus verified and the test is considered as valid. The BOD28 value of test chemical was observed to be 1.469 mgO2/mg. ThOD was calculated as 2.237 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 65.66%.Based on the results, the test item, under the test conditions, was considered to be readily biodegradable at 20 ± 1°C over a period of 28 days.

Description of key information

28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the test chemical (Experimental study report, 2015). 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 100 mg/L, while that of inoculum was 100 mg/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 item and reference item. The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 227.4%. The DO depletion (mg O2/l) in control on 28th day is 19.1 mg O2/l which full fills the control validity criteria (i.e., The DO depletion 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 acetate exceeds 168.29% after 7 days and 212.76 % after 14 days. The activity of the inoculum is thus verified and the test is considered as valid. The BOD28 value of test chemical was observed to be 1.469 mgO2/mg. ThOD was calculated as 2.237 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 65.66%.Based on the results, the test item, under the test conditions, was considered to be readily biodegradable at 20 ± 1°C over a period of 28 days.

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 (2015),28-days Manometric respirometry test 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 100 mg/L, while that of inoculum was 100 mg/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 item and reference item. The % degradation of procedure control (reference substance) was also calculated using BOD & ThOD and was determined to be 227.4%. The DO depletion (mg O2/l) in control on 28th day is 19.1 mg O2/l which full fills the control validity criteria (i.e., The DO depletion 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 acetate exceeds 168.29% after 7 days and 212.76 % after 14 days. The activity of the inoculum is thus verified and the test is considered as valid. The BOD28 value of test chemical was observed to be 1.469 mgO2/mg. ThOD was calculated as 2.237 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 65.66%.Based on the results, the test item, under the test conditions, was considered to be readily biodegradable at 20 ± 1°C over a period of 28 days.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test chemical (HSDB and PubChem, 2017). The study was performed according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test) under aerobic conditions. Activated sludge was used as a test inoculums for the study. Test substance undergoes 75% degradation by BOD parameter in 28 days and 10-day window criteria is fulfilled during the study. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

 

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