2-Methoxy-4-methylphenyl methyl carbonate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24-08-2012 to 29-03-2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met with acceptable deviations.

Qualifier:

according to guideline

Guideline:

other: State Environmental Protection Administration of China. The Guidelines for the Testing of Chemicals, 301 D Closed Bottle Test. First edition. Beijing: China Environmental Science Press. 2004. 350-356.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

pH at initiation not measured (test item has no ionisable groups) and temperature exceeded guideline specified range of 22 + 2°C. Actual: 15.4 - 26.5 °C. Not considered to impact reliability of the study.

Qualifier:

according to guideline

Guideline:

other: GB/T 21831-2008 Chemicals-Ready Biodegradability: Closed Bottle Test

Qualifier:

according to guideline

Guideline:

other: State Environmental Protection Administration of China. The Guidelines for the Testing of Chemicals (HJ/T 153-2004). Beijing: China Environmental Science Press. 2004.

Qualifier:

according to guideline

Guideline:

other: HJ 506-2009: Water quality - Determination of dissolved oxygen - Electrochemical probe method.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh activated sludge used in the test was collected from the aeration tank of Liede Sewage Treatment Plant of Guangzhou, The People’s Republic of China. Full details of the inoculum is included in the full study report. The activated sludge of waste water treatment plant is recommended by test guideline.
- Storage conditions: See pretreatment field.
- Storage length: less than 7 days from sampling to test initiation.
- Preparation of inoculum for exposure:
- Pretreatment: The activated sludge after centrifugal separation was washed with test medium after removing the suspended solids and
coarse particles on the day of collection, the activated sludge was centrifuged at 1100 g for 10 minutes and washed with mineral medium, and the supernatant was discarded with the solid material resuspended in mineral medium. This process was repeated six times. A homogenized aliquot of the final sludge suspension was weighed and dried. The dry weight content of the activated sludge was determined as 11.4 g/L. 35 mL wet sludge was suspended in 65 mL mineral medium to concentration of 4.0 g/L (dry weight). The sludge was mixed by vortex for 5 minutes and filtered by filter paper. The filtrate was kept in aerobic conditions until use. 1 mL filtrate per litre was used to inoculate the test system.
- Concentration of sludge: 1 mL per litre of medium of filtrate of 4.0 g/L (dry weight) was added into the test suspensions, the procedure control, the inoculum blank and toxicity control.
- Water filtered: Yes.
- Type and size of filter used, if any: The water for preparing medium and solution was made by the Water Purifier through deionisation.

Duration of test (contact time):

28 d

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Solution A [KH2PO4: 8.50 g; K2HPO4.3H2O: 28.50 g; Na2HPO4.12H2O: 67.15 g; NH4Cl: 0.50 g - 1L water]; Solution B [CaCl2: 27.5 g in 1L water]; Solution C [MgSO4.7H2O: 22.5 g in 1L water]; Solution D [FeCl3,6H2O: 0.25 g in 1L water]. 54 mL of solution A was mixed with 54 ml of solutions B, C and D and made up to 54 L with deionised water.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 20 ±1 °C (actual: 15.4 – 26.5 °C)
- pH: 7.4 (medium)
- pH adjusted: Not reported. Although the pH values of all vessels was to be: pH 7.4 ± 0.2 at the start of the test
- Aeration of dilution water: Not reported
- Continuous darkness: Yes.

TEST SYSTEM
- Culturing apparatus: BOD bottles with continuous stirring (magnetic stirrer)
- Number of culture flasks/concentration: 14 BOD bottles (Test suspension and Inoculum blank); 10 BOD bottles (Procedure control and Toxicity control)
- Measuring equipment: The dissolved oxygen concentrations were determined electrochemically using an oxygen electrode (Oxi 730 probe dissolved oxygen analyser and meter).
- Test performed in closed vessels due to significant volatility of test substance: No.
- Test performed in open system: No.

SAMPLING
- Sampling frequency: Duplicate bottles of all series were withdrawn for dissolved oxygen analysis at time intervals (0d, 4d, 8d, 12d, 14d, 19d, 24d, 28d) over the 28 days incubation. Procedure and toxicity controls were analyzed until day 14.
- Sampling method: Analyses of the dissolved oxygen concentration
- Sterility check if applicable: No.
- Sample storage before analysis: Not applicable.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes.
- Abiotic sterile control: No.
- Toxicity control: Yes.
- Other: Positive reference control (Sodium Benzoate).

Reference substance:

benzoic acid, sodium salt

Remarks:

2.0 mg/L

Test performance:

See 'details on results'.

Parameter:

% degradation (O2 consumption)

Value:

80.2

Sampling time:

28 d

Remarks on result:

other: mean degradation (n=2); 10-day window met

Details on results:

Results:
1. The two replicates of the test suspensions attained 80.6% and 79.7% degradation in 28 days, the mean degradation was 80.2%. The 10-day window criteria was met (start day 4 = 13.0% and end between day 7 and day 11. End day 11: 70.9%).
2. Toxicity control attained 76.5% degradation after 14 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study.
3. Reference item (Sodium Benzoate) attained ca. 100% degradation after 14 days thereby confirming the suitability of the inoculum and test conditions.
Validity Criteria:
1. The residual concentration of oxygen in the test bottles was > 0.5 mg/L during the test period (minimum dissolved oxygen concentration 2.05 mg/L).
2. The oxygen depletion in the inoculum blank was < 1.5 mg/L on day 28 (0.28 mg/L).
3. The percentage degradation of the procedure control and the toxicity control were ca. 100% and 76.5%, which had reached the pass levels of 60% and 25% of ThOD on 14d.
4. The difference of extremes of replicate values of the removal of the test substance at the plateau, at end of the test or at the end of the 10-d window was less than 20% (actual day-28: 80.6% and 79.7%).
5. The test temperature variation range was 15.4°C - 26.5°C, which exceeded the normal range (20°C ± 2°C). Time points when the test temperature was in the range 15.4°C - 17.9°C were 119, and time points when the test temperature was in the range 22.1°C - 26.5°C were 48 (the temperature was recorded once an hour). After the test temperature was found to exceed the normal range, the temperature control facility was adjusted accordingly to make the temperature return to the normal range as soon as possible. It was considered the test results revealed that the experiment met the quality requirements and the deviation did not affect the validity of the test results.

Results with reference substance:

Degradation of sodium benzoate exceeded 80 % after 14 days; actual mean (n=2) = 85.3 %: the activity of the inoculum was thus verified (validity criterion).

Table 1: Dissolved oxygen concentration (mg O2/L) and calculated % biodegradation for test suspension, inoculum blank, reference control and toxicity control

Type of suspension

0

4

7

11

14

21

28

mg O2/L

(%) biodeg (average)

mg O2/L

(%) biodeg

mg O2/L

(%) biodeg

mg O2/L

(%) biodeg

mg O2/L

(%) biodeg

mg O2/L

(%) biodeg

mg O2/L

(%) biodeg

Test suspension

8.52; 8.60

-

7.73; 7.67

12.5; 13.6 (13.0)

5.46; 5.56

58.8; 57.0 (57.9)

4.75; 4.72

70.6; 71.1 (70.9)

3.90; 4.13

87.4; 83.2 (85.3)

4.03; 4.02

78.8; 79.0 (78.9)

3.95; 4.00

80.6; 79.7 (80.2)

Inoculum blank

8.55; 8.59

-

8.23; 8.27

-

8.46; 8.48

-

8.38; 8.40

-

8.46; 8.43

-

8.10; 8.12

-

8.12; 8.14

-

Reference control

8.41; 8.53

-

6.37; 6.31

58.1; 59.9 (59.0)

5.98; 6.00

76.4; 75.8 (76.0)

5.80; 5.78

79.3; 79.9 (79.6)

4.75; 4.69

112; 114 (113)

-

-

-

-

Toxicity control

8.72; 8.75

-

5.77; 5.69

32.2; 33.1 (32.7)

4.58; 4.49

48.4; 49.4 (48.9)

3.41; 3.40

60.9; 61.0 (61.0)

2.05; 2.16

77.2; 75.9 (76.5)

-

-

-

-

  Mean values in brackets

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The mean biodegradation in duplicate was 80.2 % at day 28. The 10-day window criteria was met.

Executive summary:

The ready biodegradability test was carried out according to OECD TG 301D and China Guidelines for the Testing of Chemicals, Effects on Degradation and Accumulation, 301D Closed Bottle Test (2004) under GLP. The test substance, at a concentration of 3 mg/L was exposed to activated sewage sludge micro-organisms obtained from the Liede Sewage Treatment Plant of Guangzhou, China, with culture medium in sealed culture vessels in the dark at approximately 20°C ± 2°C (actual temperature: 15.4 to 26.5°C) for 28 days. The temperature deviation was not considered to impact the study. The sludge was diluted to 1 mL per litre of medium of filtrate of 4.0 g/L (dry weight) was added into the test suspensions, the procedure control, the inoculum blank and toxicity control. The degradation of the test substance was assessed by the regular measurement of oxygen consumption from days 0 and 28 using an Oxit 730 oxygen consumption and dissolved oxygen concentration system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. The mean oxygen uptake of the inoculum blank was 0.28 mg/L, less than 1.5 mg/L in 28-days. The difference of extremes of replicate values of the removal of the test substance at the plateau, at end of the test or at the end of the 10-d window was less than 20% (actual day-28: 80.6 % and 79.7 %). The mean percentage degradation of the procedure control and the toxicity control were ca.100 % and 76.5%, which had reached the pass levels of 60% and 25% of ThOD on 14d. The toxicity test attained 60 % degradation after 28 days thereby confirming that the test substance was not inhibitory to the sewage treatment micro-organisms used in the study. Sodium Benzoate attained ca. 100% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions. The test system therefore met the validation criteria of the guideline. The mean biodegradation for duplicate test flasks at 4 days for the test substance was 13.0 %. The mean biodegradation for duplicate test flasks at 14 days for the test substance was greater than 80 %. The mean biodegradation for duplicate test flasks at 28 days for the test substance was 80.2 % (the 10-day window was met). Under the conditions of the study, test item is considered as readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: February 2011; signature: September 2011

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): A mixed population of activated sewage sludge micro-organisms (Test System) was obtained from the secondary treatment stage of the sewage treatment plant at Villette (Geneva, Switzerland)), which treats predominantly domestic sewage.
- Storage conditions: See pretreatment field.
- Storage length: < 1 week
- Preparation of inoculum for exposure:
- Pretreatment: The sample of activated sewage sludge was maintained on continuous aeration upon receipt. A sample of the activated sewage sludge was washed three times by settlement (centrifuge) and suspension in culture medium. To remove any excessive amounts of Dissolved Organic Carbon (DOC) that may have been present, the solution was stirred and maintained on with pure oxygen at room temperature. Determination of dry weight is made to inoculate final solution with 30mg/L dry weight activated sludge.
- Concentration of sludge: The sludge was diluted in the BOD bottles to 30 mg DW/L.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

other: Test material (test 1)

Initial conc.:

99.65 mg/L

Based on:

other: Test material (test 2)

Initial conc.:

99.9 mg/L

Based on:

other: Test material (test 3)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: See table 1. 10 mL of Solution A [KH2PO4: 8.50 g/L; K2HPO4: 21.75g/L; Na2HPO4,2H2O: 33.40 g/L; NH4Cl: 0.50 g/L]; 1 mL of Solution B [CaCl2,2H2O: 36.40 g/L]; 1 mL of Solution C [MgSO4,7H2O: 22.50 g/L]; 1 mL of Solution D [FeCl3,6H2O: 0.25 g/L] and purified water diluted to 1 L.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 ±1 °C
- pH: See table 1.
- pH adjusted: No. (final pH was in the range of 7.34 to 7.46 for test item vessels)
- Aeration of dilution water: Not reported
- Suspended solids concentration: 30 mg/L dry weight
- Continuous darkness: No. The test was conducted in diffuse light.

TEST SYSTEM
- Culturing apparatus: 1000mL glass flasks with continuous stirring (fill volume ca. 200 mL)
- Number of culture flasks/concentration: In triplicate (test item); In duplicate (Inoculum blank); single flasks (Abiotic Sterile Control and toxicity control)
- Method used to create aerobic conditions: Sealed flasks wth sensor head/CO2 trap.
- Measuring equipment: The respirometer used during this study is an Oxitop Control System (WTW oxitopC). Evolved carbon dioxide is absorbed by the CO2 trap.

SAMPLING
- Sampling frequency: Daily.
- Sampling method: The respirometer used during this study is an Oxitop Control System.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. See table 1.
- Abiotic sterile control: Yes.
- Toxicity control: Yes.
- Other: Positive reference control (Sodium Benzoate).

Reference substance:

benzoic acid, sodium salt

Remarks:

100.15 mg/L

Test performance:

1. The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance at end of 10-day window and on day 28. Therefore, the test is considered valid.
2. The BOD of the inoculated blank control was 31 mgO2/L and < 60 mgO2/L after 28 days
3. The pH at day 28 was in the range of 6.0 to 8.5 (actual 7.34 to 7.46 for test item vessels)
4. The toxicity test attained 88% degradation after 28 days thereby confirming that the test material was not toxic to the sewage treatment microorganisms used in the study.
5. Sodium Benzoate attained 93% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

Parameter:

% degradation (O2 consumption)

Value:

94

Sampling time:

28 d

Remarks on result:

other: test 1; 10-day window met

Parameter:

% degradation (O2 consumption)

Value:

87

Sampling time:

28 d

Remarks on result:

other: test 2 ; 10-day window met

Parameter:

% degradation (O2 consumption)

Value:

83

Sampling time:

28 d

Remarks on result:

other: test 3 ; 10-day window met

Details on results:

The 10-day window criteria was met in all replicates (between day 3 and day 10)

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The mean biodegradation in triplicate was 88 % at day 28. The 10-day window criteria was met.

Executive summary:

The ready biodegradability test was carried out according to OECD TG 301F guideline under GLP. The test substance, at a concentration of 100.00 mg/L in test 1, at a concentration of 99.65 mg/L in test 2 and at a concentration of 100.15 mg/L in test 3 was exposed to activated sewage sludge micro-organisms obtained from the secondary treatment stage of the sewage treatment which treats predominantly domestic sewage (Villette: Geneva, Switzerland) with culture medium in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days. The sludge was diluted in the BOD bottles to 30 mg DW/L. The degradation of the test substance was assessed by the measurement of daily oxygen consumption on days 0 and 28 using an Oxitop control system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. In all of the test inoculum blanks the oxygen uptake was < 32 mg O2/L. The pH value at the end of the test period 28 days did not exceed 7.46 in the test item systems and 7.86 in the reference item system. The test system met the validation criteria of the guideline. The toxicity test attained 88% degradation after 28 days thereby confirming that the test substance was not inhibitory to the sewage treatment micro-organisms used in the study. Sodium Benzoate attained 93% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions. The mean biodegradation for triplicate test flasks at 28 days for the test substance was 88% and the 10-day window was met. Under the conditions of the study, test item is considered as readily biodegradable.

Description of key information

1. Biodegradation: mean biodegradation 80.2% (28-days; 10-day window met), OECD TG 301D, 2013

2. Biodegradation: mean biodegradation 88.0% (28-days; 10-day window met), OECD TG 301F, 2011

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

OECD TG 301D, 2013 - The ready biodegradability test was carried out according to OECD TG 301D and China Guidelines for the Testing of Chemicals, Effects on Degradation and Accumulation, 301D Closed Bottle Test (2004) under GLP. The test substance, at a concentration of 3 mg/L was exposed to activated sewage sludge micro-organisms obtained from the Liede Sewage Treatment Plant of Guangzhou, China, with culture medium in sealed culture vessels in the dark at approximately 20°C ± 2°C (actual temperature: 15.4 to 26.5°C) for 28 days. The temperature deviation was not considered to impact the study. The sludge was diluted to 1 mL per litre of medium of filtrate of 4.0 g/L (dry weight) was added into the test suspensions, the procedure control, the inoculum blank and toxicity control. The degradation of the test substance was assessed by the regular measurement of oxygen consumption from days 0 and 28 using an Oxit 730 oxygen consumption and dissolved oxygen concentration system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. The mean oxygen uptake of the inoculum blank was 0.28 mg/L, less than 1.5 mg/L in 28-days. The difference of extremes of replicate values of the removal of the test substance at the plateau, at end of the test or at the end of the 10-d window was less than 20% (actual day-28: 80.6 % and 79.7 %). The mean percentage degradation of the procedure control and the toxicity control were ca.100 % and 76.5%, which had reached the pass levels of 60% and 25% of ThOD on 14d. The toxicity test attained 60 % degradation after 28 days thereby confirming that the test substance was not inhibitory to the sewage treatment micro-organisms used in the study. Sodium Benzoate attained ca. 100% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions. The test system therefore met the validation criteria of the guideline. The mean biodegradation for duplicate test flasks at 4 days for the test substance was 13.0 %. The mean biodegradation for duplicate test flasks at 14 days for the test substance was greater than 80 %. The mean biodegradation for duplicate test flasks at 28 days for the test substance was 80.2 % (the 10-day window was met). Under the conditions of the study, test item is considered as readily biodegradable.

 

OECD TG 301F, 2011 - The ready biodegradability test was carried out according to OECD TG 301F guideline under GLP. The test substance, at a concentration of 100.00 mg/L in test 1, at a concentration of 99.65 mg/L in test 2 and at a concentration of 100.15 mg/L in test 3 was exposed to activated sewage sludge micro-organisms obtained from the secondary treatment stage of the sewage treatment which treats predominantly domestic sewage (Villette: Geneva, Switzerland) with culture medium in sealed culture vessels in diffused light at 22°C ± 1°C for 28 days. The sludge was diluted in the BOD bottles to 30 mg DW/L. The degradation of the test substance was assessed by the measurement of daily oxygen consumption on days 0 and 28 using an Oxitop control system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. In all of the test inoculum blanks the oxygen uptake was < 32 mg O2/L. The pH value at the end of the test period 28 days did not exceed 7.46 in the test item systems and 7.86 in the reference item system. The test system met the validation criteria of the guideline. The toxicity test attained 88% degradation after 28 days thereby confirming that the test substance was not inhibitory to the sewage treatment micro-organisms used in the study. Sodium Benzoate attained 93% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions. The mean biodegradation for triplicate test flasks at 28 days for the test substance was 88% and the 10-day window was met. Under the conditions of the study, test item is considered as readily biodegradable.

 

References:

1. ECHA Guidance on Information Requirements and Chemical Safety Assessment (Chapter R.7b: Endpoint Specific Guidance, R.7.9.4, June 2017)

2. Introduction to the section of the OECD Guidelines for Testing of Chemicals on Degradation and Accumulation, Section 3 (OECD, September 2006)

3. GHS revision 4 (2011), Globally harmonized system of classification and labelling of chemicals (GHS). Chapter 4.1. Hazardous to the aquatic Environment. United Nations, 2011

4. ECHA Guidance on Application on the CLP Criteria, section 4.1.3.2.3.2 (v5.0, July 2017)