7,11-dimethyldodeca-4,6,10-trien-3-one

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was conducted between 14 October 2016 and 28 February 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: ECHA Guidance for the implementation of REACH, Guidance on information requirements and chemical safety assessment, Chapter R.7b: Endpoint specific guidance, November 2014 (version 2.0)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

7,11-dimethyldodeca-4,6,10-trien-3-one

EC Number:

247-878-3

EC Name:

7,11-dimethyldodeca-4,6,10-trien-3-one

Cas Number:

26651-96-7

Molecular formula:

C14H22O

IUPAC Name:

(4E,6E)-7,11-dimethyldodeca-4,6,10-trien-3-one

impurity 1

Reference substance name:

3,6,10-trimethylundeca-3,5,9-trien-2-one

EC Number:

214-245-8

EC Name:

3,6,10-trimethylundeca-3,5,9-trien-2-one

Cas Number:

1117-41-5

Molecular formula:

C14H22O

IUPAC Name:

3,6,10-trimethylundeca-3,5,9-trien-2-one

Test material form:

liquid

Specific details on test material used for the study:

Lot No.: SC00018390
Aspect: yellow liquid
Purity: 89.1% 7,11-dimethyldodeca-4,6,10-trien-3-one (sum of the isomers)
6.4% 3,6,10-trimethylundeca-3,5,9-trien-2-one (sum of the isomers)

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, industrial (adaptation not specified)

Details on inoculum:

- Source of activated sludge: Domestic sewage works, Bois-de-Bay, Satigny, Switzerland.
- Sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium).
- The sludge was kept under aerobic conditions and used the same day.

Duration of test (contact time):

62 d

Initial test substance concentration

Initial conc.:

30 mg/L

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

APPARATUS
- Respirometer: Oxitop Control System

WATER
- Ultrapure water containing less than 5 ppb total organic carbon was used during the study.

STOCK SOLUTIONS
- Solution A: KH2PO4 8.5 g; K2HPO4 21.75 g, Na2HPO4.2H2O 33.4 g; NH4Cl 0.5 g (dissolved in water and made up to 1 L).
- Solution B: CaCl2 27.5 g (dissolved in water and made up to 1 L).
- Solution C: MgSO4.7H2O 22.5 g (dissolved in water and made up to 1 L).
- Solution D: FeCl3.6H2O 0.25 g; concentrated HCl one drop (dissolved in water and made up to 1 L).

MINERAL MEDIUM
- Solution A (50 mL) and deionised water (2000 mL) were mixed and Solution B (5 mL), Solution C (5 mL) and Solution D (5 mL) added before making up to 5 L with deionised water.

DETERMINATION OF DRY WEIGHT OF SUSPENDED SOLIDS
- Two 50 mL samples of the homogenised sludge were taken and water was evaporated on a steam bath, dried in an oven at 105-110 °C for two hours, and weighing the residue.

FLASK PREPARATION
- Test substance samples (13.10 mg, corresponding to 30 mg/L in 437 mL) were weighed in small aluminium boats and added to the contents of the test flasks of the Oxitop.
- For reference substance samples 43.70 mg (corresponding to 100 mg/L in 437 mL of test medium) were weighed in small aluminium boats and added to the contents of the test flasks of the Oxitop.
- Flasks were filled with 432 mL of mineral medium.
- Suspended sludge diluted to a concentration of 2.62 g/L dry matter was added.
- pH of each flask was not measured but assumed to be the same as the mineral medium.
- Two sodium hydroxide pellets were placed in the quivers on top of the bottle.
- The flasks were then closed tightly with the measuring heads and allowed to equilibrate to the test temperature.
- After temperature equilibration, the controller of the instrument starts the data acquisition (time zero of the experiment).

TEST CONDITIONS
- Temperature (20.5°C - 21.7 °C) and stirring were checked daily.
- Oxygen consumption of each flask was recorded daily.

NOMINAL CONCENTRATIONS
- Test material: 30 mg/L
- Reference substance: 100 mg/L

TOXICITY CONTROL
- An optional toxicity control was not performed. The validity of the study was not adversely affected.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

- The activity of the inoculum was verified.
- The repeatability validity criterion (not more than 20% difference between replicates) was fulfilled. Therefore, the test was considered valid.

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

65

Sampling time:

28 d

BOD5 / COD results

Results with reference substance:

Degradation of reference substance sodium benzoate exceeded 40 % (after 7 days) and 65 % (after 14 days). For details see Appendix 4 of attached study report 16 - E331.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Pseudoisoraldeine A did not significantly inhibit the intrinsic respiration of the inoculum at the test concentration and was considered to be non-toxic to the inoculum at the test concentration.

Pseudoisoraldeine A undergoes 65% biodegradation after 28 days in the test conditions. The 10-day window criterion is not fulfilled (12% biodegradation on day 3 and 50% on day 13). The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a "standard" growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted March 2006), states that if a substance consists of "constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commencial forms" and "it is anticipated that a sequential biodegration of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test". The 10-day time-window should therefore not be appled as a pass / fail criterion for Pseudoisoraldeine A.

Thus, Pseudoisoraldeine A should be regarded as readily biodegradable according to the test based on the biodegration percentage of 65% at day 28.

Executive summary:

The Ready Biodegradabilty of Pseudoisoraldeine A was determined by the Manometric Respirometry test.

Pseudoisoraldeine A did not significantly inhibit the intrinsic respiration of the inoculum at the test concentration and was considered to be non-toxic to the inoculum at the test concentration.

Pseudoisoraldeine A undergoes 65% biodegradation after 28 days in the test conditions. The 10-day window criterion is not fulfilled (12% biodegradation on day 3 and 50% on day 13). The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a "standard" growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted March 2006), states that if a substance consists of "constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commencial forms" and "it is anticipated that a sequential biodegration of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test". The 10-day time-window should therefore not be appled as a pass / fail criterion for Pseudoisoraldeine A.

Thus, Pseudoisoraldeine A should be regarded as readily biodegradable according to the test based on the biodegration percentage of 65% at day 28.