Ethyl 2,4-dimethyl-1,3-dioxolane-2-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:

19 March 2002 to 16 April 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Niedersächsisches Umweltministerium, Hannover, Germany (d.d. 2002-03-11)

Specific details on test material used for the study:

- Solubility in water: 71.70 g/L (at room temperature)
- Storage at the test facility: Refrigerator 7 ± 2 °C, protected from light and moisture
- Expiry date: 2002-08-31

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: lnoculum of the aqueous phase of non-adapted activated sludge was used. The activated sludge was derived from the municipal sewage treatment plant, D-31137 Hildesheim which treats mostly municipal sewage and hardly industrial chemical waste.
- Pre-treatment: The activated sludge was filtered with folded filter. The first 200 mL of the filtrate were not used. The second filtrate effluent from the domestic waste water was used to initiate inoculation.
- Initial cell/biomass concentration: 1.0E+04 - 1.0E+06 colony-forming units (CFU)

Duration of test (contact time):

28 d

Initial conc.:

ca. 4 mg/L

Based on:

test mat.

Initial conc.:

ca. 7.36 mg/L

Based on:

ThOD

Remarks:

(1.84 mg O2/mg test substance)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Nutrient medium 'Stock solution 1':
- Composition: According to OECD 301 D
- Temperature: 20 °C (as measured in demineralised water after aeration).
- pH: 7.42 (as measured in nutrient medium 'Stock solution 1'). Determined using pH-Meter, "CORNING" pH 240
- Aeration of dilution water: One day before the test started the demineralized water for the test medium was aerated until oxygen saturation and then left at room temperature for at least 20 h. The oxygen content was 11.2 mg/L.
- Test medium:
- Preparation of test solutions: All test solutions were made as stock solutions. 0.2 mL of the inoculum was given in each BOD bottle. The stock solutions were filled to the BOD bottles with a siphon.
The incubation vessels were closed without air bladders.
- Test temperature: 20.1 - 20.4 °C (measured daily).
- Test pH (begin-end): Inoculum control: 8.04-7.96; functional control: 7.66-7.32; test item: 7.67-7.38; toxicity control: 7.69-7.29.

TEST SYSTEM
- Culturing apparatus: BOD bottles with glass stoppers (nominal volume 300 mL).
- Test volume: 300 mL.
- Number of culture flasks: 10 bottles containing 4 mg/L test item and inoculum (test suspension); 10 bottles containing only inoculum (inoculum control); 10 bottles containing 10 mg/L reference item and inoculum (functional control) and 10 bottles containing 2 mg/L test item and 5 mg/L reference item and inoculum (toxicity control). All tests were performed in duplicate (i.e. 5 x 2 bottles).
- Measuring equipment: Oxygen concentrations were determined using Oximeter, "WTW" Oxi 530. pH values were determined using pH-Meter, "CORNING" pH 240.
- Test performed in open system: yes

SAMPLING
- Frequency: The oxygen concentration was measured in the incubation vessels an day 0, 7, 14, 21 and 28. All measurements were performed in duplicate.

CONTROL AND BLANK SYSTEM
- Inoculum blank: nutrient solution and inoculum
- Toxicity control: 2.0 mg/L test item + 5.0 mg/L reference item + nutrient solution and inoculum
- Functional control: see below (Reference substance)

Reference substance:

acetic acid, sodium salt

Remarks:

10 mg/L based on test. mat / 7.8 mg/L based on ThOD.

Key result

Parameter:

% degradation (O2 consumption)

Value:

10

Sampling time:

28 d

Details on results:

- Functional control: The adaptation phase transformed to a degradation phase after 1 day (degradation >10%). The pass level >60% was reached after 5 days. After 7 days a rate of 73% was observed and the plateau reached.
- Toxicity control: Biodegradation of reference item + test item was 36% after 14 days (maximum of 44% after 28 days). The biodegradation of the reference item was not inhibited by the test item.
- 10-day window criterion: Not met.

Table: Oxygen determinations and percentage biodegradation

Day	Inoculum control		Test item (ThOD = 7.36)			Functional control (ThOD = 7.8 mg/L)			Toxicity control (ThOD = 7.58)
	O2		O2	BOD	Degr.	O2	BOD	Degr.	O2	BOD	Degr.
	mg/L*	depl.	mg/L*	mg/L	%	mg/L*	mg/L	%	mg/L*	mg/L	%
0	10.42	-	10.63	-	-	10.40	-	-	10.45	-	-
7	9.55	0.87	9.64	0.12	2	3.88	5.65	73	7.15	2.43	32
14	9.16	1.26	9.22	0.15	2	3.79	5.35	69	6.43	2.76	36
21	9.17	1.25	8.84	0.54	8	3.47	5.68	73	6.56	2.64	35
28	9.10	1.32	8.57	0.74	10	3.03	6.05	78	6.86	3.27	44

* Mean value of 2 duplicates

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on materials and methods incl. tables'.

Interpretation of results:

not readily biodegradable

Conclusions:

The substance is not readily biodegradable.

Executive summary:

The biodegradation potential of the substance was examined in a study according to OECD TG 301D (Closed Bottle test) and in compliance with GLP criteria.

Test item at a concentration of 4 mg/L (ca. 7.36 mg/L based on ThOD) was inoculated for 28 days under aerobic conditions with inoculum of the aqueous phase of non-adapted activated sludge derived from a municipal sewage treatment plant. In addition, an inoculum control, a reference control (10 mg/L sodium acetate) and a toxicity control (with 2 mg/L test substance and 5 mg/L reference substance) were run in parallel. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 0 and after 7, 14, 21, and 28 days of exposure. Cumulative percentages biodegradation were calculated from the oxygen depletion ratio BOD/ThOD. All validity criteria were met.

After the 28-day incubation period the substance was biodegraded for 10%. Based on thise finding, the substance is classified as not readily biodegradable.

Description of key information

The biodegradation potential of the substance was examined in a study according to OECD TG 301D (Closed Bottle test) and in compliance with GLP criteria (Dr. Noack, 2017).

Test item at a concentration of 4 mg/L (ca. 7.36 mg/L based on ThOD) was inoculated for 28 days under aerobic conditions with inoculum of the aqueous phase of non-adapted activated sludge derived from a municipal sewage treatment plant. In addition, an inoculum control, a reference control (5 mg/L sodium acetate) and a toxicity control (with 2 mg/L test substance and 5 mg/L reference substance) were run in parallel.Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 0 and after 7, 14, 21, and 28 exposure. Cumulative percentages biodegradation were calculated from the oxygen depletion ratio BOD/ThOD. All validity criteria were met.

After the 28-day incubation period the substance was biodegraded 10%. Based on these findings the substance is classified as not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed