2-methylvaleric acid

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented publication which meets basic scientific principles; method used is similar to OECD TG 301 D (closed bottle test)

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1971

Report date:

1971

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

; pre-guidelin study, no duplicates, limited reporting

Principles of method if other than guideline:

Tests were performed similar to the method of OECD TG 301 D - Closed Bottle Test. The consumption of dissolved oxygen was measured using a polarographic electrode. Aim of the study was to compare the biodegradability of a variety of chemical substances. Amongst others, biodegradability of linear and branched saturated aliphatic carboxylic acids was investigated.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-methylvaleric acid

EC Number:

202-594-9

EC Name:

2-methylvaleric acid

Cas Number:

97-61-0

Molecular formula:

C6H12O2

IUPAC Name:

2-methylpentanoic acid

Details on test material:

- Name of test material (as cited in study report): 2-methylvaleric acid
- Source: K & K Laboratories

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): domestic sewage, not further specified
- Method of cultivation: raw sewage was stored at 25°C for 24 to 48 hr prior to use
- Preparation of inoculum for exposure: sewage was filtered through cotton

Duration of test (contact time):

10 d

Initial test substance concentration

Initial conc.:

2 other: mg Carbon/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: American Public Health Association (1965) Standard methods for the examination of water and wastewater, 12th edition. American Public Health Association, New York
- Additional substrate: glucose in a second series of experiments to test for toxicity of test substances
- Test temperature: 25°C
- pH: 6.5 - 7.5
- pH adjusted: yes
- Aeration of dilution water: no data
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 300 mL BOD bottles
- Measuring equipment: oxygen electrode

SAMPLING
- Sampling frequency: none; electrodic oxygen measurements in test flasks

Results and discussion

Test performance:

Carboxylic acids and methyl-substituted carboxylic acids including isovaleric acid were readily metabolised

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

71.8

Sampling time:

10 d

Remarks on result:

other: % O2 consumption of ThOD

Details on results:

Oxygen consumption (mg/L) BOD (mg O2/mg Substance) % Degr. (BOD/ThOD)
Day 2: 3.5 1.0856 49.3
Day 5: 4.8 1.4888 67.6
Day 10: 5.1 1.5813 71.8

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

Based on the oxygen consumption, 2-methylvaleric acid is rapidly biodegraded.

Executive summary:

The biodegradability of 2-methylvaleric acid and numerous related substances (aliphatic acids and alcohols) was determined in a pre-guideline study. Reporting is limited but the test procedure follows in general the method of OECD TG 301 D (Closed Bottle Test).

 

Non-adapted sewage of a domestic sewage treatment plant served as inoculum. Test substance was incubated for 10 days at 25°C in the dark. No parallels were set up. Dissolved oxygen was measured at three time points (2, 5, and 10 days).

 

After 10 days, 2-methylvaleric acid was degraded to ca. 72% (day 5: ca. 68%) (calculated from the originally reported data of oxygen consumption). Based on the oxygen consumption data, 2-methylvaleric acid is readily biodegradable (Dias and Alexander, 1971).

 

This pre-guideline study provides evidence that aliphatic alcohols and acids (linear and methyl-substituted are rapidly biodegraded. Results are estimated to adequately represent the biodegradability of these substances.