3,7-dimethyloct-1-en-3-yl acetate

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:

13 October 2015 to 22 February 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

ISO 14593:1999 (Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Method by analysis of inorganic carbon in sealed vessels (CO2 headspace test))

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

Version / remarks:

23 March 2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- CAS no.: 68345-17-5

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage
- Laboratory culture:
The freshly obtained sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was determined to be 3.8 g/L in the concentrated sludge. Before use, the sludge was allowed to settle (60 minutes) and the liquid was decanted for use as inoculum at the amount of 10 mL/L of mineral medium.
In general, bottles were filled to give a headspace to liquid ratio of 1:2 (107 mL test medium in 160 mL-capacity bottle).
- Water filtered: yes
- Type and size of filter: Tap-water was purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon and ion-exchange cartridges (Milli-Q) (Millipore Corp., Bedford, Mass., USA). Milli-RO water : carbon levels < 500 ppb.

Duration of test (contact time):

28 d

Initial conc.:

1.477 mg/L

Based on:

IC (inorganic carbon)

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: 1 L mineral medium contains: 10 mL of solution (A),
1 mL of solutions (B) to (D) and Milli-RO water.
Stock solutions of mineral components
A)8.50 g KH2PO4
21.75 g K2HPO4
67.20 g Na2HPO4.12H2O
0.50 g NH4Cl
dissolved in Milli-Q water and made up to 1 L, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H2O dissolved in Milli-Q water and made up to 1 L
C) 36.40 g CaCl2.2H2O dissolved in Milli-Q water and made up to 1 L
D) 0.25 g FeCl3.6H2O dissolved in Milli-Q water and made up to 1 L
- Test temperature: room temperature
- pH: At the start of the test period the pH values of the different test media were 7.4 (abiotic control) and 7.8 (inoculum blank, procedure control, test item and toxicity control).
- Aeration of dilution water: no
- Suspended solids concentration: 3.8 g/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Well sealed glass serum bottles.
- Number of culture flasks/concentration: Five test bottles for analysis at the end of the test and triplicate test bottles for other time intervals for each treatment.
- Method used to create aerobic conditions: bottles were filled to give a headspace to liquid ratio of 1:2 (107 mL test medium in 160 mL-capacity bottle).

SAMPLING
- Sampling frequency: Inoculum blank, test item and abiotic control: day 1, 7, 14, 21 and 28. Procedure control and toxicity control: day 1, 7 and 14.

CONTROL AND BLANK SYSTEM
- Inoculum blank: containing inoculated medium
- Abiotic sterile control: containing untreated medium, test item and sterilising agent (1 mL of a solution containing 10 g/L of HgCL2 (99.99%, Sigma-Aldrich, Steinheim, Germany).
- Toxicity control: containing inoculated medium, reference item and test item.

Reference substance:

other: 1-Octanol

Key result

Parameter:

% degradation (inorg. C analysis)

Value:

14

Sampling time:

28 d

Details on results:

The relative biodegradation values calculated from the measurements performed revealed 14% biodegradation of Dimethyl Octenyl Acetate (based on IC) at the end of 28-day test period. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. In the toxicity control less than 25% biodegradation occurred within 14 days (18% at the end of the 28-day test period, based on ThCO2). Therefore, the test item was assumed to have a small inhibiting effect on microbial activity.

Results with reference substance:

The reference item was degraded by 64.3 % after 14 days, based on measurement of inorganic carbon.

 

 

 

 

Table 1 Biodegradation (%) based on measurement of inorganic carbon (IC)

Day	Reference item	Test item	Toxicity control	Abiotic control
1	1.2	1.5	0.9	-0.3
7	36.0	5.4	24.5	-1.3
14	64.3	14.7	18.2	-1.9
21	n.a.	20.9	n.a.	-3.5
28	n.a.	13.5	n.a.	-4.5

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Dimethyl Octenyl Acetate was not readily biodegradable under the conditions of the head space test.

Executive summary:

The study procedures described in this report were based on the OECD guideline No. 310, 2006. In addition, the procedures were designed to meet the test methods of the ISO International Standard 14593, 1999.

The test item was added to the mineral medium to give a final organic carbon concentration of 20 mg C/L. The organic carbon content (73%) was based on the molecular formula. Since Dimethyl Octenyl Acetate was not sufficiently soluble to allow preparation of a 100-times concentrated stock solution in mineral medium, a known amount of 3.36 μL, corresponding with 2.9 mg Dimethyl Octenyl Acetate was added to the test bottles containing medium with microbial organisms and mineral components (107 mL). The test solutions were continuously shaken during the test, to ensure optimal contact between the test item and the test organisms.

The test was performed in sealed bottles with a headspace of air. The test consisted of five groups:

• Inoculum blank: containing inoculated medium

• Procedure control: containing inoculated medium and reference item.

• Test item: containing inoculated medium and test item.

• Toxicity control: containing inoculated medium, reference item and test item.

• Abiotic control: containing untreated medium, test item and sterilising agent.

The CO2 evolution resulting from the aerobic biodegradation of the test item was determined by measuring the inorganic carbon (IC) produced in the test bottles in excess of that produced in blank vessels containing inoculated medium only. Biodegradation was expressed as a percentage of the theoretical maximum IC production, based on the quantity of test item (as organic carbon) initially added.

The relative biodegradation values calculated from the measurements performed revealed 14% biodegradation of Dimethyl Octenyl Acetate (based on IC) at the end of 28-day test period. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. In the toxicity control less than 25% biodegradation occurred within 14 days (18% at the end of the 28-day test period, based on ThCO2). Therefore, the test item was assumed to have a small inhibiting effect on microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. In conclusion, Dimethyl Octenyl Acetate is designated as not readily biodegradable.

Description of key information

The registration substance was found to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

The study procedures described in this report were based on the OECD guideline No. 310, 2006. In addition, the procedures were designed to meet the test methods of the ISO International Standard 14593, 1999.

The test item was added to the mineral medium to give a final organic carbon concentration of 20 mg C/L. The organic carbon content (73%) was based on the molecular formula. Since Dimethyl Octenyl Acetate was not sufficiently soluble to allow preparation of a 100-times concentrated stock solution in mineral medium, a known amount of 3.36 μL, corresponding with 2.9 mg Dimethyl Octenyl Acetate was added to the test bottles containing medium with microbial organisms and mineral components (107 mL). The test solutions were continuously shaken during the test, to ensure optimal contact between the test item and the test organisms.

The test was performed in sealed bottles with a headspace of air. The test consisted of five groups:

• Inoculum blank: containing inoculated medium

• Procedure control: containing inoculated medium and reference item.

• Test item: containing inoculated medium and test item.

• Toxicity control: containing inoculated medium, reference item and test item.

• Abiotic control: containing untreated medium, test item and sterilising agent.

The CO2 evolution resulting from the aerobic biodegradation of the test item was determined by measuring the inorganic carbon (IC) produced in the test bottles in excess of that produced in blank vessels containing inoculated medium only. Biodegradation was expressed as a percentage of the theoretical maximum IC production, based on the quantity of test item (as organic carbon) initially added.

The relative biodegradation values calculated from the measurements performed revealed 14% biodegradation of Dimethyl Octenyl Acetate (based on IC) at the end of 28-day test period. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. In the toxicity control less than 25% biodegradation occurred within 14 days (18% at the end of the 28-day test period, based on ThCO2). Therefore, the test item was assumed to have a small inhibiting effect on microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. In conclusion, Dimethyl Octenyl Acetate is designated as not readily biodegradable.