2-(2-ethoxyethoxy)ethyl 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:

23 Jul - 20 Sep 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Circular on Test Methods of New Chemical Substances (Japan), Biodegradation test

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment

Details on inoculum:

- Source of inoculum/activated sludge (location, sampling depth): location: 10 sites (4 sewage plants, 3 rivers, 1 lake and 2 bays) around Japan, sampling depth: return sludge in sewage plants, surface water and surface soil of foreshore
- Laboratory culture: Thirty minutes after stopping of aeration, discard about one third of the whole volume of supernatant and add an equal volume of a solution (pH adapted to 7.0 with NaOH) containing 0.1% each of glucose, peptone and potassium orthophosphate, to the settled material and re-commence aeration. This procedure was repeated once per day.
- Temperature: 25 ± 2 °C
- Storage conditions: observed appearance and general condition of sludge, determined sediments, pH, temperature and dissolved oxygen and observed with a light microscope, whether it is normal.
- Storage length: started to use: 16 Jul 1991
- Preparation of inoculum for exposure: Activated sludge from STP mixed with
- Concentration of sludge: 4600 mg/L
- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: recommended medium in the guideline
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L
- pH: 5.6 - 7.2

TEST SYSTEM
- Culturing apparatus: closed oxygen consumption measuring machine with 300 mL culture bottle (coulometer)
- Number of culture flasks/concentration: 1 (water + test substance), 3 (sludge + test sub.), 1 (sludge + reference sub.), 1 (sludge)
- Measuring equipment: Coulometer
- Details of trap for CO2 and volatile organics if used: soda lime

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes

Reference substance:

aniline

Remarks:

100 mg/L

Key result

Parameter:

% degradation (O2 consumption)

Value:

101

Sampling time:

28 d

Details on results:

No 10-day window required. Substance was readily biodegradable.

Results with reference substance:

The oxygen consumption for aniline in the above used test system reached 68% and 90% degradation after 7 days and 14 days.

Table 1. Results of analysis for BOD, DOC and GC

		water + test sub.	sludge + test sub.			Theoretical Amount
		sample No. 4	sample No. 1	sample No. 2	sample No. 3
BOD (*1)	mg	0.0	53.8	57.0	56.0	55.1
DOC (residue of test substance)	mg	16.5	0.9	0.8	0.8	16.5
	% (*2)	100	5	5	5
GC	mg	28.6	0	0	0	30.3
	% (*2)	94	0	0	0

(*1) (sludge + test sub.) was calculated by substracting blank values.

(*2) Residue and production percentage was calculated as followed.

Residue percentage = Residue amount (mg) / Theoretical amount (mg) x 100

Table 2. Chart of BOD

	BOD (mg)
	7thday	14thday	28thday
Sludge + Test substance	27.2	52.8	60.0
Sludge + Test substance	26.8	57.8	63.2
Sludge + Test substance	34.0	58.5	62.2
Water + Test substance	0.0	0.0	0.0
Control blank	1.5	3.5	6.2
Sludge + Aniline	63.2	84.5	91.8

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Complete biodegradation was observed after 28 days. Since the substance reached the pass level of > 60% after 28 days (no 10-day window required for OECD 301C), 2-(2-ethoxyethoxy)ethyl acetate is regarded as being readily biodegradable according to the OECD criteria.

Executive summary:

Ready biodegradability has been investigated in a study performed according to OECD TG 301C employing a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum. Complete biodegradation was observed after 28 days. Since the substance reached the pass level of > 60% after 28 days (no 10-day window required for OECD 301C), 2-(2-ethoxyethoxy)ethyl acetate is regarded as being readily biodegradable according to the OECD criteria.

Description of key information

Readily biodegradable: 101% (BOD) after 28 d (OECD 301C)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

One experimental study supported by handbook data is available investigating the ready biodegradability of 2-(2-ethoxyethoxy)ethyl acetate (CAS 112-15-2). The key study was performed according to OECD 301C (GLP) with a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum (Ministry of Economy, Trade and Industry, Japan, 1991). A mean biodegradation of 101% was observed after 28 d. Since the substance reached the pass level of > 60% after 28 d (no 10-day window required for OECD 301C), 2-(2-ethoxyethoxy)ethyl acetate is stated to be readily biodegradable according to the OECD criteria. Further handbook data indicate a biodegradation of 90.1% (O2 consumption) after 20 d (Verschueren, 1996) for this substance. Since no guideline is mentioned and no degradation kinetics are available, this result cannot be used for an assessment of ready biodegradability of the test substance. Nevertheless, it supports the result from the key study and therefore, extensive biodegradation of 2-(2-ethoxyethoxy)ethyl acetate can be assumed . In conclusion, 2-(2-ethoxyethoxy)ethyl acetate can be classified as readily biodegradable according to the OECD criteria.