1-methoxy-4-[3-methyl-4-(2-phenylethoxy)but-3-en-1-yl]benzene

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

Study period:

10-03-2021 to 06-07-2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

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)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Guidelines for the Testing of Chemicals, Effects on Degradation and Accumulation, Version 2, 301F Manometric Respirometry Test, China Environmental Press, China (2013)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: National Standardization Technical Committee for the Management of Hazardous Chemicals. GB/T 21801-2008 Chemicals-Ready Biodegradability Manometric Respirometry Test [S]. China Standard Press (2008)

Deviations:

no

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 Suzhou Drainage Company Ltd., domestic waste sewage treatment plant : Suzhou city, The People’s Republic of China. The batch number 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: ca. 1 week; i.e. maximum 7 days from sampling to test initiation.
- Preparation of inoculum for exposure: The freshly sampled activated sludge was collected from the aeration basin and kept aerobic during transport. See pretreatment field for further information.
- Pretreatment: The activated sludge was filtered through fine filter sieve to remove the coarse particles, washed using the test medium and settled for ca. 10 minutes, after which the supernatant was discarded. The sludge was resuspended in test medium, repeated 3 times. An amount of 10 mL washed activated sludge was sampled (4 replicates) and dried at 105 °C for 2 hours to determine the concentration of suspended solid (SS}, which was determined to be 3.2 g SS/L and aerated for 2 days at 22 ± 2 °C until required. Before test, the activated sludge suspended solid was determined to be 3.2 g SS/L. From this result, the added amount of activated sludge was calculated.
- Concentration of sludge: The inoculum was added into the test suspensions, the procedure control, the inoculum blank and toxicity control to give a final concentration of 30.0 mg SS/L.
- Water filtered: Yes.
- Type and size of filter used, if any: Fine filter, not otherwise specified. The water for preparing medium and solution was made by the Water Purifier (to analytical grade water, i.e. organic carbon concentration < or = 2 ppb). For each series of tests, the same synthetic media was used (details reported in the full study report).

Duration of test (contact time):

28 d

Initial conc.:

ca. 18.8 mg/L

Based on:

test mat.

Remarks:

mean (n=2) concentration

Initial conc.:

ca. 50.88 mg/L

Based on:

ThOD

Remarks:

mean (n=2) concentration based on ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Solution A [KH2PO4: 8.5031 g; K2HPO4.3H2O: 21.7504 g; Na2HPO4.12H2O: 67.1502 g; NH4Cl: 0.5030 g – made up to 1000 mL in purified water. The pH value was measured to be 7.68 then adjusted to 7.48 with HCI (aq)]; Solution B [CaCl2: 9.1006 g made up to 250 mL water] ; Solution C [MgSO4.7H2O: 5.6256 g made up to 250 mL water] ; Solution D [FeCl3,6H2O: 0.0626 g made up to 250 mL water with one drop HCl (aq)].
8 Litres test medium was prepared : 80 mL of stock solution A was firstly mixed with purified water, and then 8.000 mL of stock solution B, C and D were added, mixed thoroughly and made up to 8 Litres with purified water. The pH value was measured to be 7.74. Then the pH adjusted to 7.49 with HCl(aq).
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 ±1 °C (actual: 21.1 – 22.8 °C)
- pH: 7.49 (medium) and pH 7.67-7.80 at the end of the test.
- pH adjusted: No (not adjusted at end of test, since the pH was not outside the range of 6.0 to 8.5).
- Aeration of dilution water: Not reported
- Suspended solids concentration: The inoculum was added into the test suspensions, the procedure control, the inoculum blank and toxicity control to give a final concentration of 30.0 mg SS/L.
- Continuous darkness: No. Test conducted under diffuse light

TEST SYSTEM
- Culturing apparatus: Flasks with continuous stirring (magnetic stirrer)
- Number of culture flasks/concentration: In duplicate (Inoculum blank); duplicate (test system); single flasks (procedure control and toxicity control)
- Method used to create aerobic conditions: Screw sealed flasks with sensor head/CO2 trap.
- Method used to create anaerobic conditions: Not applicable.
- Measuring equipment: The respirometer used during this study is : BOD Analyzer: Aerobic respirometer, England CES, No.: TTE20170918
- Test performed in closed vessels due to significant volatility of test substance: No.
- Test performed in open system: Not applicable.
- Details of trap for CO2 and volatile organics if used: 5 mL of 2 mol/L sodium hydroxide was added to CO2 absorption traps.
- Other: Not applicable.

SAMPLING
- Sampling frequency: Daily (BOD)
- Sampling method: Respirometry measuring the oxygen uptake of the test medium.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. See table 1.
- Abiotic sterile control: No.
- Toxicity control: Yes.
- Other: Positive reference control ('Procedure control' ; Sodium Benzoate).

Reference substance:

benzoic acid, sodium salt

Remarks:

32.48 mg/L

Test performance:

(1) The oxygen uptake of the inoculum blanks were 37 mg/L, which was less than 60 mg/L in 28-d.
(2) At the end of the test, the pH values of each test vessel were 7.67-7.80, which was within the range of 6.0-8.5.
(3) The difference of extremes of replicate values of the removal of the test item at the plateau, at end of the test or at the end of the 10-d window was less than 20% (actual day 11: 17.1% and 10.2% and actual day-28: 71.2% and 74.3%).
(4) The percentage degradation of the procedure control and the toxicity control were 94.4% and 80.7%, which had reached the pass levels of 60% and 25% of ThOD on 14d.
All validity criteria were considered to be met.

Key result

Parameter:

% degradation (O2 consumption)

Value:

72.75

Sampling time:

28 d

Remarks on result:

other: n=2; 10-d window met

Details on results:

The test item was degraded based on BOD: actual mean = 72.7% (n=2 ; 71.2% and 74.3%) at day 28
At the end of the 10-day window the test item was degraded by mean = 61.3% (n=2; 63.7% and 59.0%). The 10-day window criterion was met.

Results with reference substance:

Degradation of sodium benzoate exceeded 88.6% after 14 days: the activity of the inoculum was thus verified (validity criterion).

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item mean biodegradation in duplicate was 72.7 % at day 28 based on BOD (10-day window met).

Executive summary:

The ready biodegradability test was carried out according to OECD TG 301F and China Guidelines for the Testing of Chemicals, Effects on Degradation and Accumulation, Version 2, 301F Manometric Respirometry Test (2013) under GLP. The test substance, at a concentration of 30 mg/L was exposed to activated sewage sludge micro-organisms obtained from the Suzhou Drainage Company Ltd., domestic waste sewage treatment plant of Suzhou city, China, with culture medium in sealed culture vessels in diffuse light at 22°C ± 1°C for 28 days. The sludge was diluted in flasks to 30.0 mg SS/L within the test system and in the negative and toxicity controls. The degradation of the test item was assessed by daily measurement of oxygen consumption from days 0 and 28 using a respirometer system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. The oxygen uptake of the inoculum blank was 37.4 mg/L, which was less than 60 mg/L in 28-days. At the end of the test, the pH values of each test vessel were within the range of 6.0-8.5 (actual pH: 7.67 – 7.80). 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 11: 17.1% and 10.2% and actual day-28: 71.2% and 74.3%). The percentage degradation of the procedure control and the toxicity control were 94.4% and 80.7%, which had reached the pass levels of 60% and 25% of ThOD on 14 days. The toxicity test attained 60 % degradation after 28 days thereby confirming that the test item was not inhibitory to the sewage treatment micro-organisms used in the study. Sodium Benzoate attained 94.4% 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 10 days for the test item was 9.0%. The mean biodegradation for duplicate test flasks at 11 days and 21 days for the test flasks was 13.7% and 61.4%, respectively. The mean biodegradation at 28 days for the test item was 72.7% (the 10-day window was met). Under the conditions of the study, test item is considered as readily biodegradable.

Description of key information

Biodegradation: readily biodegradable, mean biodegradation 72.7% at 28-days, 10-day window met ; OECD TG 301F, 2021

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Key study : OECD TG 301F, 2021 :  The ready biodegradability test was carried out according to OECD TG 301F and China Guidelines for the Testing of Chemicals, Effects on Degradation and Accumulation, Version 2, 301F Manometric Respirometry Test (2013) under GLP. The test substance, at a concentration of 30 mg/L was exposed to activated sewage sludge micro-organisms obtained from the Suzhou Drainage Company Ltd., domestic waste sewage treatment plant of Suzhou city, China, with culture medium in sealed culture vessels in diffuse light at 22°C ± 1°C for 28 days. The sludge was diluted in flasks to 30.0 mg SS/L within the test system and in the negative and toxicity controls. The degradation of the test item was assessed by daily measurement of oxygen consumption from days 0 and 28 using a respirometer system. Control solutions with inoculum and the reference substance, sodium benzoate, together with a toxicity control were used for validation purposes. The oxygen uptake of the inoculum blank was 37.4 mg/L, which was less than 60 mg/L in 28-days. At the end of the test, the pH values of each test vessel were within the range of 6.0-8.5 (actual pH: 7.67 – 7.80). 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 11: 17.1% and 10.2% and actual day-28: 71.2% and 74.3%). The percentage degradation of the procedure control and the toxicity control were 94.4% and 80.7%, which had reached the pass levels of 60% and 25% of ThOD on 14 days. The toxicity test attained 60 % degradation after 28 days thereby confirming that the test item was not inhibitory to the sewage treatment micro-organisms used in the study. Sodium Benzoate attained 94.4% 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 10 days for the test item was 9.0%. The mean biodegradation for duplicate test flasks at 11 days and 21 days for the test flasks was 13.7% and 61.4%, respectively. The mean biodegradation at 28 days for the test item was 72.7% (the 10-day window was met). Under the conditions of the study, test item is considered as readily biodegradable.