2-ethylbutyric acid

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:

key study

Study period:

2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Duration of test (contact time):

14 d

Initial conc.:

100 mg/L

Parameter followed for biodegradation estimation:

TOC removal

Reference substance:

aniline

Key result

Parameter:

other: BOD (%)

Value:

93

Sampling time:

14 d

Key result

Parameter:

% degradation (TOC removal)

Value:

96

Sampling time:

14 d

Parameter:

other: HPCL (%)

Value:

100

Sampling time:

14 d

Details on results:

No degradation products were identified.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

2-Ethylbutyric acid was found to have a BOD, TOC (removal), and HPLC of 93, 96, and 100 %, respectively. No degradation products were identified. The registered substance was concluded to be readily biodegradable under the conditions of this test (CLP Regulation (EC) No 1272/2008).

Executive summary:

To assess the capacity of 2-ethylbutyric acid to be readily biodegraded in the environment, a 14-day experiment was undertaken according to Good Laboratory Practise (GLP) and a modified version of OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). The purpose of this procedure is to determine the biodegradability of an organic substance in a freshwater environment. The test system was aerobic and with an activated sludge non-adapted inoculum that was subject to an inital test concentration of 100 mg/l. A blank control, water + test substance, and sludge + aniline (reference substance) treatment was prepared (n = 1) in conjunction with a sludge + test substance treatment (n = 3). At the termination of the 14-day test period, biological oxygen demand (BOD), total organic carbon (TOC), and HPLC was determined to be 93, 96, and 100 %, respectively. No degradation products were identified. Given that percentage biodegradation (based on TOC) was 96 % within a 14-day test period, 2-ethylbutyric acid was concluded to be readily biodegradable under the conditions of the test (CLP Regulation (EC) No 1272/2008).

Reference 2

Endpoint:

biodegradation in water: screening test, other

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2000

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Insufficient information for an assessment of reliability.

Principles of method if other than guideline:

A test system was prepared that consisted of a river sediment inoculum incubated within an anaerobic chamber for 300 hours at 35 °C, which was exposed to an initial test concentration of 16 mmol/L. Results were analysed by gas chromatography. The purpose of the study was to determine the degradation pathways within natural anaerobic systems of a number of persistent branched fatty acids, including 2-ethylbutyric acid.

GLP compliance:

no

Oxygen conditions:

anaerobic

Inoculum or test system:

natural sediment

Initial conc.:

16 mmol/L

Degradation products were identified following exposure of the anaerobic sediment system to 2-ethylbutyric acid. Specifically, in the headspace of the culture carbon dioxide and methane were identified and in the culture medium, acetic acid and butanoic acid were detected.

Validity criteria fulfilled:

not specified

Interpretation of results:

other: biodegradation observed

Conclusions:

An anaerobic river sediment inoculum was exposed to 2-ethylbutyric acid as part of a larger study to determine potential degradation pathways in a number of persistent fatty acids. Biodegradation was observed during the experiment, with breakdown products such as carbon dioxide and methane detected in the headspace of the flasks and acetic acid and butanoic acid within the medium.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

April 2018

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

results derived from a (Q)SAR model, with limited documentation / justification

Qualifier:

no guideline followed

Principles of method if other than guideline:

BioWin v4.10 is a Structure Activity Relationship (SAR) model in Epi Suite™ that can be used to qualitatively estimate the aerobic and anaerobic biodegradability of organic substances based on the fragments within the molecule.

GLP compliance:

no

Oxygen conditions:

aerobic/anaerobic

Key result

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks on result:

readily biodegradable based on QSAR/QSPR prediction

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

Based on a Quantitative Structure-Activity Relationship (QSAR) prediction in BioWin v4.10, 2-ethylbutyric acid was estimated to be readily biodegradable with an ultimate degradation timeframe of 3.3071 days - weeks and primary degradation timeframe of 4.0657 days.

Description of key information

2-Ethylbutyric acid has been concluded to be readily biodegradable according to a 14-day BOD of 93 %, TOC of 96%, and HPLC of 100 % following exposure of non-adapted activated sludge inoculum to 100 mg/l (CLP Regulation (EC) No 1272/2008). No biodegradation products were identified. As part of an anaerobic study that involved the exposure of 2-ethylbutyric acid to natural river sediment, biodegradation was observed with such breakdown products identified as carbon dioxide, methane, acetic acid, and butanoic acid. In support of 2-ethylbutyric acid being readily biodegradable, a prediction in BioWin v4.10 rendered a YES estimate to readily biodegradability with an ultimate degradation timeframe of 3.3071 days - weeks and primary degradation timeframe of 4.0657 days.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater