2-ethyl-2-oxazoline

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Specific details on test material used for the study:

Purity: 99%

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: secondary effluent from an activated sludge plant treating domestic sewage
- Preparation of inoculum for exposure: collected effluent first passed through a coarse filter (Whatman No. 1) to remove particulate matter. Level of inorganic carbon was reduced before use by sparging with CO2-free air for about 1hr while maintaining the pH at 6.5.
- Concentration of sludge: 30 mg/L of activated sludge
- Type and size of filter used, if any: Whatman No. 1

Duration of test (contact time):

28 d

Initial conc.:

> 2 - < 10 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

inorg. C analysis

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST SYSTEM
- Culturing apparatus: volumetric apparatus; 100 (+/-1) ml of the mineral salts media is dispensed into '125 ml' Hypo-Vial [Pierce Warriner (UK) Ltd]. Vials are sealed with butyl rubber septa and aluminium crimp seals and placed on an orbital shaker in a temperature controlled environment.
- Number of culture flasks/concentration: 10

SAMPLING
- Sampling frequency: Every 4th day
- Sampling method: A vessel is removed from the shaker as required, a sample of the headspace gas withdrawn using a gas syringe and the concentration of CO2 determined. The seal is then broken and the concentration of dissolved inorganic carbon (DIC) in the solution is measured immediately.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Controls containing the same inoculum concentration but no test compound are also prepared.

STATISTICAL METHODS:
- the mean % biodegradation, standard deviations and 95% Confidence Intervals

Parameter:

% degradation (CO2 evolution)

Value:

93.4

St. dev.:

1.55

Sampling time:

22 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

91.8

Sampling time:

28 d

Details on results:

The % degradation of the test substance was reported as 93.4% after 22 days in the Sealed Vessel Test. The % degradation of the test substance was reported as 91.8% after 28 days in the Sturm Test. Test substance shown to be readily and ultimately biodegradable.

Review of the data presented in the graphical representation of the % degradation over time confirms the sample degraded reaching approximate 10% degradation around day 2 and >80% around day 12. Therefore, the sample met the 10 -day window criteria.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

The ready biodegradability of 2-aminoethanol was studied in a Sturm test equivalent to OECD 301B. The test substance was degraded to 91.8 % after 28 days. The substance 2-aminoethanol was shown to be readily and ultimately biodegradable under the conditions of the test.

Executive summary:

The ready biodegradability of 2-aminoethanol was studied in a Sturm test equivalent to OECD 301B. The test substance was degraded to 91.8 % after 28 days. The substance 2-aminoethanol was shown to be readily and ultimately biodegradable under the conditions of the test.

 

Review of the data presented in the graphical representation of the % degradation over time confirms the sample degraded reaching approximate 10% degradation around day 2 and >80% around day 12. Therefore, the sample met the 10 -day window criteria.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: Warburg Respirometer (standard manometric technique)

Version / remarks:

American Public Health Association Standard Methods for the Examination of Water and Wastewater 12th edition, 1965

Principles of method if other than guideline:

Method: Warburg respirometer test

Principle of Method: Standard Methods for the Examination of Water and Wastewater has represented "the best current practice of American water analysts." This comprehensive reference covers all aspects of water and wastewater analysis techniques. Standard Methods is a joint publication of the American Public Health Association (APHA), the American Water Works Association (AWWA), and the Water Environment Federation (WEF).

GLP compliance:

no

Remarks:

Study pre-dates GLP

Specific details on test material used for the study:

Purity not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Before use, the raw sewage was stored at 25 °C for 24 to 48 hr; it was then filtered through cotton, and 5.0 ml was added per liter of dilution water.

Cultures were grown in 250 or 500 mL of medium contained in 1.0 or 2.0 L flasks maintained on a rotary shaker at 25 °C for 48 hrs. Cells were collected by centrifugation, washed once with 0.10M phosphate buffer, and then resuspended in the same buffer.

Duration of test (contact time):

30 d

Initial conc.:

2 mg/L

Based on:

IC (inorganic carbon)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Bottles were sealed and oxygen uptake was monitored as the measure of oxidation of the test substance. Bottles were incubated at 25 °C in the dark.Additional tests were performed with glucose to assess toxicity of the test substance on the inoculum.

Reference substance:

other: glucose

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

2 d

Parameter:

% degradation (O2 consumption)

Value:

71

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

10 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

74

Sampling time:

30 d

Details on results:

The results indicate that propionic acid should biodegrade under aerobic conditions. Theoretical BOD values were corrected for endogenous respiration. Oxygen consumption was 3.6, 4.3, 4.5, and 4.6 mg/L on days 2, 5, 10, and 30, respectively.

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

The ready biodegradability of propionic acid was studied in a Warburg Respirometer test. The test substance was degraded to 74% after 30 days. The substance propionic acid was shown to be readily biodegradable under the conditions of the test.

Executive summary:

The ready biodegradability of propionic acid was studied in a Warburg Respirometer test. The test substance was degraded to 74% after 30 days. The substance propionic acid was shown to be readily biodegradable under the conditions of the test.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Data for 2-aminoethanol (ethanolamine; CAS No. 141-43-5) and propionic acid (CAS No. 79-09-4) will be used to address the ready biodegradability requirement for 2-ethyl-2-oxazoline (CAS No. 10431-98-8) in an analogue read-across approach. The basis for this read-across approach is that the inoculum is expected to rapidly transform the target substance into ethanolamine and propionic acid. The biodegradability of the ethanolamine transformation product will be assessed using information on ethanolamine, and the biodegradability of the propionic acid transformation product will be assessed using information on propionic acid.

2. SOURCE AND TARGET CHEMICAL(S)
The target substance is known to be of high purity (typically 99.5 % w/w), and to contain up to 1 % w/w (typically 0.5 % w/w) of its 2-methyl analogue as an impurity. The impurity is expected to undergo the same transformation steps as the target substance, producing exactly the same ethanolamine transformation product but an analogous acetic acid transformation product in place of the propionic acid transformation product. On this basis, the source substances effectively represent typically >99.5 % w/w of the target substance. The purities of the samples of source substances that were tested are not specifically known, but it is assumed that they would not have been sufficiently impure as to substantially affect the study results. On this basis, the applicability of the data on the source substances to the target substance is not expected to be compromised by the presence of impurities in any of the substances.
See attached report for further details.

3. ANALOGUE APPROACH JUSTIFICATION
The basis for this read-across approach is that the target substance is expected to be rapidly transformed by the inoculum into ethanolamine and propionic acid.
This transformation that is expected to occur in man is expected also to be affected by the broader range of enzymes, particularly esterases and amidases, available within the diverse population of bacteria that compose the inoculum.
The ethanolamine transformation product is clearly identical to the first source substance, and the amount produced will be equivalent to 62% w/w of the loading of target substance.
The propionic acid transformation product is clearly identical to the second source substance, and the amount produced will be equivalent to 75% w/w of the loading of target substance.
The sum of the above values exceeds 100% due to the mass added by the incorporation of water of hydrolysis.
See attached report for full details.

4. DATA MATRIX
See attached report

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Specific details on test material used for the study:

The 2-ethyl-2-oxazoline biodegradability is predicted based on the results of the ethanolamine and propionic acid.

Key result

Remarks on result:

other: Readily biodegradable based on read-across

Details on results:

As both source substances are readily biodegradable, the target substance is predicted to be readily biodegradable.

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

Since both ethanolamine and propionic acid have been shown to be readily biodegradable, the target substance can confidently be predicted also to be readily biodegradable.

Description of key information

No test data to address the ready biodegradability of the target substance is available. Therefore, information for two source substances, 2-aminoethanol (ethanolamine; CAS No. 141-43-5) and propionic acid (CAS No. 79-09-4), are presented to address this endpoint. The basis for this read-across approach is that the inoculum is expected to rapidly transform the target substance into the two source substances. 

 

The ready biodegradability of propionic acid was studied in a Warburg Respirometer test. The test substance was degraded to 74% after 30 days. The substance propionic acid was shown to be readily biodegradable under the conditions of the test.

 

The ready biodegradability of 2-aminoethanol was studied in a Sturm test equivalent to OECD 301B. The test substance was degraded to 91.8 % after 28 days. The substance 2-aminoethanol was shown to be readily and ultimately biodegradable under the conditions of the test. Review of the data presented in the graphical representation of the % degradation over time confirms the sample degraded reaching approximate 10% degradation around day 2 and >80% around day 12. Therefore, the sample met the 10 -day window criteria.

 

Since both ethanolamine and propionic acid have been shown to be readily biodegradable, the target substance can confidently be predicted also to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater