2-octyldodecyl 12-[(1-oxooctadecyl)oxy]octadecanoate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

86

St. dev.:

3.5

Sampling time:

28 d

Remarks on result:

other:

Remarks:

for 20 mg test item /L test assays

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

According to the OECD guideline 301F, the test item can be considered as readily biodegradable (86.0% in 28 d, O2 consumption).

Executive summary:

The ready biodegradability of the test item was investigated according to the manometric respirometry test design and carried out according to the OECD guideline for Testing of Chemicals No. 301 F (1992) and the Council Regulation (EC) No 440/2008 of 30 May 2008. The ready biodegradability of the test item was investigated at a concentration of at a concentration of 100 mg/L (ThOD = 305 mg/L) and 20 mg/L (ThOD = 61 mg/L), respectively, in a manometric respirometry test using domestic aerobic activated sewage sludge incubated at 22°C in the dark over 28 days under continuous stirring. The biochemical oxygen demand (BOD) was measured daily and the percentage degradation was calculated from the theoretical oxygen demand (ThOD) after correcting for the BOD of inoculum controls. The biodegradation of the test item in the static test was found to be at mean 66 % with a standard deviation of 1.4 % for a concentration of 100 mg test item per liter and at mean 86 % with a standard deviation of 3.5 % for a concentration of 20 mg test item per liter after 28 days. For a concentration of 100 mg test item per liter biodegradation within the 10-day-window was found to be 43 %. For a concentration of 20 mg test item per liter biodegradation within the 10-day-window was found to be 80 %. The test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration. In the procedural controls, the reference substance sodium benzoate was degraded by an average of 86 % by exposure day 14, and reached an average biodegradation of 91 % by the end of the test (day 28), thus confirming suitability of the activated sludge.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 Aug - 07 Sep 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany
- Date of sampling: 10th August 2016
- Storage conditions: No storage
- Preparation of inoculum for exposure: No washing, the concentration was adjusted to 3.0 g/L and verified by dry mass measurement.
- Pretreatment: Kept aerobic until use
- Concentration of sludge in the test: 29.6 mg dry mass/litre

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Remarks:

corresponding to 305 mg ThOD / L

Initial conc.:

20 mg/L

Based on:

test mat.

Remarks:

corresponding to 61 mg ThOD / L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

- The concentration in the test assays were 100 and 20 mg per litre mineral test medium (25 and 5 mg/250 mL), respectively. 100 mg test item correspond to 305.3 mg ThOD. 20 mg test item correspond to 61.1 mg ThOD. The required amount of test item was added directly on a weight basis via Teflon discs. Subsequently, the required volume of aqueous reference stock solution (if applicable) and mineral medium were added to the vessels.
- The concentration in the test vessels with reference item (procedural control, toxicity control) was 100 mg per litre mineral test medium (25 mg/250 mL).
- A further solution containing both test and reference item at the same concentrations as in the individual solutions (test item 100 mg/L, reference item 100 mg/L) was prepared to determine the possible toxicity of the test item against the inoculum.
- Further flasks with mineral medium only were prepared for inoculum controls.
- Abiotic controls were also prepared to measure any possible abiotic degradation; a solution of the test item at about 100 mg/L was sterilized by the addition of 1 mL/L HgCl2 (10 g/L).
- In all test assays except of the abiotic controls, 2.47 mL of the inoculum stock solution were transferred for inoculation (per 250 mL) resulting in a concentration of 29.6 mg dry mass/litre (7.4 mg dry mass/250 mL).

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

86

St. dev.:

3.5

Sampling time:

28 d

Remarks on result:

other:

Remarks:

for 20 mg test item /L test assays

Details on results:

The biodegradation of isocetyl stearoyl stearate after 28 days of incubation in the static test was found to be 66 % (SD = 1.4 %) and 86 % (SD = 3.5 %) in the assays with 100 mg/L and 20 mg/L, respectively. The biodegradation within the 10-day-window was 43 % and 80 % in the assays with 100 mg/L and 20 mg/L, respectively. The 10-day-window started at day 3 in the assays with 100 mg/L and at day 2 - 3 in the assays with 20 mg/L.

Results with reference substance:

The reference item sodium benzoate was degraded to 86 % within the first 14 days. At the end of the test
(Day 28), the reference item was degraded by an average of 91 %.

Percent degradation. Degradation (%) after 14 days.

vessel		Test suspension 100 mg/L	Test suspension 20 mg/L	Abiotic control	Procedural control	Toxicity control
1		45.2	88.4	0.0	86.5	42.8
2		45.9	78.6	0.0	84.7	47.5
Mean		45.5	83.5	0.0	85.6	45.1
SD		0.5	6.9	0.0	1.3	3.3

Percent degradation. Degradation (%) after 28 days.

vessel		Test suspension 100 mg/L	Test suspension 20 mg/L	Abiotic control	Procedural control	Toxicity control
1		67.5	88.4	0.0	91.3	57.4
2		65.5	83.5	0.0	91.3	64.2
Mean		66.5	86.0	0.0	91.3	60.8
SD		1.4	3.5	0.0	0.0	4.8

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

According to the OECD guideline 301F, the test item can be considered as readily biodegradable.

Executive summary:

The ready biodegradability of the test item was investigated according to the manometric respirometry test design and carried out according to the OECD guideline for Testing of Chemicals No. 301 F (1992) and the Council Regulation (EC) No 440/2008 of 30 May 2008. The ready biodegradability of the test item was investigated at a concentration of at a concentration of 100 mg/L (ThOD = 305 mg/L) and 20 mg/L (ThOD = 61 mg/L), respectively, in a manometric respirometry test using domestic aerobic activated sewage sludge incubated at 22°C in the dark over 28 days under continuous stirring. The biochemical oxygen demand (BOD) was measured daily and the percentage degradation was calculated from the theoretical oxygen demand (ThOD) after correcting for the BOD of inoculum controls. The biodegradation of the test item in the static test was found to be at mean 66 % with a standard deviation of 1.4 % for a concentration of 100 mg test item per liter and at mean 86 % with a standard deviation of 3.5 % for a concentration of 20 mg test item per liter after 28 days. For a concentration of 100 mg test item per liter biodegradation within the 10-day-window was found to be 43 %. For a concentration of 20 mg test item per liter biodegradation within the 10-day-window was found to be 80 %. The test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration. In the procedural controls, the reference substance sodium benzoate was degraded by an average of 86 % by exposure day 14, and reached an average biodegradation of 91 % by the end of the test (day 28), thus confirming suitability of the activated sludge.

Description of key information

Readily biodegradable: 86.0% in 28 d (OECD 301F, O2 consumption); read-across

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

There is no study available assessing the ready biodegradability of the target substance 2-octyldodecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 90052-75-8). Therefore, read-across to the structurally related source substance Isohexadecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 97338-28-8) was conducted in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5. The source substance is characterized by similar fatty acid and alcohol components and is therefore considered a suitable representative for the assessment of the ready biodegradability of the target substance. A detailed justification of the analogue approach is provided in IUCLID section 13.

The study with the source substance Isohexadecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 97338-28-8) was performed according to OECD guideline 301 F and GLP.

In the manometric respirometry test, 20 mg/L (61 mg ThOD/L) and 100 mg/L (305 mg ThOD/L) test item were inoculated with 29.6 mg dry mass/L domestic activated sludge for 28 d under continuous stirring. A reference, inoculum and toxicity control were run in parallel. O2 consumption was recorded continuously and the percentage degradation was calculated from the theoretical oxygen demand (ThOD) after correcting for the BOD of inoculum controls.

After 28 d, the mean biodegradation of the test item was 66 % in the 100 mg test item/L treatment and 86 % in the 20 mg/L treatment. At the concentration level of 100 mg/L, biodegradation was 43% at the end of the 10-day-window and 80% at the concentration level of 20 mg/L. The test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 100 mg/L (mean degradation 45.1% after 14 d and 60.8% after 28 d). In the procedural controls, the reference substance sodium benzoate was degraded by an average of 86 % by exposure day 14, and reached an average biodegradation of 91 % by the end of the test (day 28), thus confirming suitability of the activated sludge. Since the guideline recommends test concentrations in the range of 50 - 100 mg ThOD/L, the results of the 20 mg/L treatment were considered the most relevant. Therefore, the test item can be considered as readily biodegradable according to the OECD guideline 301 F.

Based on the structural similarities between the target and source substance, it can be concluded that the target substance 2-octyldodecyl 12-[(1-oxooctadecyl)oxy]octadecanoate (CAS 90052-75-8) is readily biodegradable according to the OECD criteria.