5,9-dimethyldec-4-enal

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:

16-06-2017 to 28-03-2017

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)

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

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: April 2016; signature: May 2016

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 Shenyang domestic sewage treatment plant (plant 2). The sample was collected the day before test item exposure. The activated sludge of a waste water treatment plant is recommended by test guideline.
- Storage conditions: See pretreatment field.
- Storage length: ca. 1 day from sampling to test initiation.
- Preparation of inoculum for exposure:
- Pretreatment: The activated sludge after filtration and settling and supernatant discard, was washed with test mineral medium and the concentrated sludge was suspended in mineral medium. 3 replicates of 10 mL suspended sludge were weighed and dried at 105°C for around 2 hours and reweighed to calculate initial sludge
concentration. The sludge was diluted to 4.05 g/L suspended solids and kept aerobic at 21.7 to 23.7°C until the test. For the test, five replicates of 10 mL sludge were dried at 105°C for 1.5 hours and weighed with a mean concentration of 3632 mg/L suspended solids.
- 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/L (dry weight).
- Water filtered: Not reported.
- Type and size of filter used, if any: Not reported.

Duration of test (contact time):

28 d

Initial conc.:

17.5 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: 4.2509 g; K2HPO4.3H2O: 10.8753 g; Na2HPO4.12H2O: 16.7005 g; NH4Cl: 0.2507 g - in 500 mL water]; Solution B [CaCl2: 3.6408 g in 100 mL water]; Solution C [MgSO4.7H2O: 2.2509 g in 100 mL water]; Solution D [FeCl3,6H2O: 0.0253 g in 100 mL water]. 1 L mineral medium was prepared. 10 mL stock solution A was added to approximately 0.8 L distilled water and the mixture stirred before adding, sequentially, 1 mL each of stock solutions B, C and D. After mixing the mixture was made up to 1 L with distilled water. 22 L mineral medium was prepared and the pH was checked to be 7.70, and adjusted to 7.50 with HCI.
- Solubilising agent (type and concentration if used): None.
- Test temperature: 22 ±1 °C (actual: 22.1 – 22.8 °C)
- pH: 7.50 (medium)
- pH adjusted: Was not necessary as the pH values of all vessels was: pH 7.4 ± 0.2 at the start and pH 7.5 ± 0.2 at the end of the test
- Aeration of dilution water: Not reported
- Continuous darkness: No. Conducted in defuse light.

TEST SYSTEM
- Culturing apparatus: Flasks with continuous stirring (magnetic stirrer)
- Number of culture flasks/concentration: In duplicate (Inoculum blank); single flasks (procedure control and toxicity control)
- Method used to create aerobic conditions: Screw sealed flasks wth sensor head/CO2 trap.
- Measuring equipment: The respirometer used during this study is an Oxitop Control System.

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

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

Reference substance:

benzoic acid, sodium salt

Remarks:

32.1 mg/L

Test performance:

(1) The oxygen uptake of the inoculum blanks were 18.49 mg/L and 19.43 mg/L, the mean was 18.96 mg/L, less than 60 mg/L in 28d.
(2) At the end of the test, the pH values of each test vessel were 7.52-7.74, within the range of 6.0-8.5.
(3) 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: 11.5%).
(4) The percentage degradation of the procedure control and the toxicity control were 71.0% and 70.7%, which had reached the pass levels of 60% and 25% of ThOD on 14d.

Parameter:

% degradation (O2 consumption)

Remarks:

mean

Value:

76.9

Sampling time:

28 d

Remarks on result:

other: n=2

Results with reference substance:

Degradation of sodium benzoate exceeded 60% (actual: 71.0 %) 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 substance mean biodegradation in duplicate was 76.9% at day 28.

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 theShenyang domestic sewage treatment plant (plant 2), China, with culture medium in sealed culture vessels in the dark at 22°C ± 1°C for 28 days. The sludge was diluted in flasks to 30.0 mg/L (dry weight) within the test system and in the negative and toxicity controls. The degradation of the test substance was assessed by the daily measurement of oxygen consumption from days 0 and 28 using a respirometer. 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 blanks were 8.49 mg/L and 19.43 mg/L, the mean was 18.96 mg/L, 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: 7.52-7.74). 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: 11.5%). The percentage degradation of the procedure control and the toxicity control were 71.0% and 70.7%, 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 76.9 % 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 28 days for the test substance was 76.9% (the 10-day window was not met). The test item was biodegraded by 76.9% at day 28 in the Manometric Respiratory Test. The 10-day window that can be applied to Manometric Respiratory Tests, where 60% biodegradation must be achieved following the attainment of 10 % biodegradation, is not applied to multi-constituent substances consisting of structurally similar constituents (OECD, 2006). Under the conditions of the study, test item is considered as readily biodegradable.

Description of key information

Biodegradation: readily biodegradable, mean biodegradation 76.9% (28-days, 10-day window not met). 10-day window not applicable to multi-constituent substances consisting of structurally similar constituents (OECD, 2006); OECD TG 301F, 2018

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Key study: OECD TG 301F, 2018 : 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 Shenyang domestic sewage treatment plant (plant 2), China, with culture medium in sealed culture vessels in the dark at 22°C ± 1°C for 28 days. The sludge was diluted in flasks to 30.0 mg/L (dry weight) within the test system and in the negative and toxicity controls. The degradation of the test substance was assessed by the daily measurement of oxygen consumption from days 0 and 28 using a respirometer. 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 blanks were 8.49 mg/L and 19.43 mg/L, the mean was 18.96 mg/L, 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: 7.52-7.74). 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: 11.5%). The percentage degradation of the procedure control and the toxicity control were 71.0% and 70.7%, 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 76.9 % 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 28 days for the test substance was 76.9% (the 10-day window was not met). The test item was biodegraded by 76.9% at day 28 in the Manometric Respiratory Test. The 10-day window that can be applied to Manometric Respiratory Tests, where 60% biodegradation must be achieved following the attainment of 10 % biodegradation, is not applied to multi-constituent substances consisting of structurally similar constituents (OECD, 2006). 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)