Isotridecyl isononanoate

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:

22nd November 2017 to 18th January 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Isotridecyl isononanoate

EC Number:

255-673-5

EC Name:

Isotridecyl isononanoate

Cas Number:

42131-27-1

Molecular formula:

C22H44O2

IUPAC Name:

Isotridecyl isononanoate

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on inoculum:

Surface water was collected from Malmesbury Pond, Sandymoor, Runcorn on13th November 2017 and assigned a batch number of SE17003. It was filtered to remove coarse particles and aerated at 22 ± 2ºC prior to use. The surface water was then added to test media so as to achieve a final concentration of 100ml per litre of test media. The test suspensions were then aerated until the study pre-conditioning period was ready to commence on 17th November 2017

Duration of test (contact time):

56 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

12.9 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

25.7 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

3.1 Test medium: Test medium was prepared according to the method detailed in Cheshire Eco Solutions SOP III.19.

3.2 Test vessels: Conical flasks containing 3000 ml of test media.

3.3 Inoculum: Surface water was collected from Malmesbury Pond, Sandymoor, Runcorn on 13th November 2017 and assigned a batch number of SE17003. It was filtered to remove coarse particles and aerated at 22 ± 2ºC prior to use. The surface water was then added to test media so as to achieve a final concentration of 100ml per litre of test media. The test suspensions were then aerated until the study pre-conditioning period was ready to commence on 17th November 2017.

3.4 Test material: Test material was added directly to the test vessels after being accurately weighed ontoglass cover slips to give a final test
concentrations of 12.9 mg/l and 25.7 mg/l. A control vessel was run in parallel, this contained inoculum but no test or reference material. A test vessel containing 102.9 mg (20 mg C/l) of the reference material, sodium benzoate (Batch No: 304526) in 3 litres of test media, was also included in the test. In addition a vessel containing 102.9 mg (20 mg C/l) of the reference material, sodium benzoate and test material at 25.7 mg/l in 3 litres of test media, was also included as an inhibition control.

3.5 Test conditions: 3 Litre volumes of test media were stirred constantly in round, flat bottomed flasks in the dark. Carbon dioxide free air was passed through the test solutions at an estimated rate of 30 to 100ml per minute. This was in turn passed through two dreschel bottles, per test vessel, containing barium hydroxide of known concentration and volume. The tests were carried out in the laboratory at 22 ± 2°C. Single vessels were prepared for each test material concentration.

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (CO2 evolution)

Value:

95.8

Sampling time:

56 d

Remarks on result:

other: Starting concentration

Remarks:

12.9 mg/l

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

44.8

Sampling time:

56 d

Remarks on result:

other: Starting concentration

Remarks:

25.7 mg/l

% Degradation 3

Parameter:

% degradation (CO2 evolution)

Value:

76.4

Sampling time:

28 d

Remarks on result:

other: Starting concentration

Remarks:

12.9 mg/l

% Degradation 4

Parameter:

% degradation (CO2 evolution)

Value:

33

Sampling time:

28 d

Remarks on result:

other: Starting concentration

Remarks:

25.7 mg/l

Details on results:

A figure of 60% degradation within 28 days is usually taken as being indicative of a good potential for degradation. According to this guideline, under these test conditions in the OECD 301B Procedure, Isotridecyl isononanoate showed good potential for degradation at the test concentration of 12.9 mg/l and limited potential at 25.7 mg/l after 28 days in this study.
After 56 days Isotridecyl isononanoate also showed good potential for degradation at the test concentration of 12.9 mg/l and limited potential at 25.7 mg/l. The final 56-day cumulative % degradation values were determined to be 95.8% at 12.9 mg/l and 44.8% at 25.7 mg/l.

Any other information on results incl. tables

Cumulative degradation
Day of Titration	Sodium Benzoate (34.3 mg/l)	Isotridecyl isononanoate (12.9 mg/l)	Isotridecyl isononanoate (25.7 mg/l)	Inhibition Control**
1	22.4	*	2.5	*
3	44.0	4.3	5.3	15.5
5	50.1	17.2	5.6	36.1
8	54.9	27.8	9.8	46.1
10	58.0	27.6	11.7	53.0
14	63.8	44.4	17.0	65.5
19	66.7	55.9	26.0	74.4
23	68.9	65.8	29.0	81.7
28	71.1	76.4	33.0	86.8
35	70.2	75.8	34.9	97.0
42	76.4	78.3	39.3	100.5
49	79.8	85.4	41.1	110.5
56	83.4	89.2	43.4	114.2
57	87.2	95.8	44.8	118.3
* Indicates negative degradation
** inhibition Control contained sodium benzoate at 34.3 mg/L and test material at 25.7 mg/l in 3 litres of test media.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

From the results of this study it can be concluded that Isotridecyl isononanoate does not meet the criteria for classification as 'readily biodegradable' according to the OECD 301B method of >60.0% biodegradation being achieved within the 10-day window. However it did prove to be ‘ultimately biodegradable’ with >60.0% biodegradation being achieved within the initial 28-day test period.

Executive summary:

While the study correctly concludes that the substance is not readily biodegradable, the criteria given in CLP on Rapid degradability of organic substances states in section 4.1.2.9.5(c) that if there is convincing evidence that >70% degradation is achieved within a 28 day period then a substance may also be considered rapidly biodegradable.

As applies to Isotridecyl isononanoate and the results obtained in this study at the 12.9 mg/L concentration (the lower threshold defined by the guideline of 10mg TOC/l), the substance can be considered rapidly biodegradable for the purposes of classification in accordance with CLP.