Reaction mass of 2-hydroxy-4-(methylthio)butanoic acid and 2-hydroxy-4-(methylthio)butanoic acid dimer

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From Sep. 25 to Oct. 23, 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP study conducted similarly to OECD guideline 301 F with deviations. No toxicity control was performed; however, the study “Activated sludge Respiration inhibition test (Monsanto study XX-91-71) shows that the test substance isn’t toxic to bacteria. This study is as a “toxicity control” for the biodeg study.

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

yes

Remarks:

no toxicity control

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-hydroxy-4-(methylthio)butyric acid

EC Number:

209-523-0

EC Name:

2-hydroxy-4-(methylthio)butyric acid

Cas Number:

583-91-5

Molecular formula:

C5H10O3S

IUPAC Name:

2-hydroxy-4-(methylthio)butanoic acid

Constituent 2

Reference substance name:

Hydroxy-2-methylthio-4-butanoic acid

IUPAC Name:

Hydroxy-2-methylthio-4-butanoic acid

Details on test material:

- Name of test material (as cited in study report): ALIMET
- Physical state: Light brown liquid
- Analytical purity: ≥ 88%
- Theoretical oxygen demand (ThOD): 1.49 mg O2/mg active
- Vapour pressure: 51-58% of vapour pressure of water at room temperature
- Density: 1.23 kg/L (20 °C)
- Water solubility: Infinite

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Mixed liquor was obtained from the aeration tank of the waste water treatment plant of Hasselt. This treatment plant was dealing predominantly with domestic sewage.
- Preparation of inoculum for exposure: Before use, the mixed liquor was sieved through a 0.5 mm sieve in order to remove large particles.
- Suspended solids content: 9.3 g/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

50 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

100 mg/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: Test medium contains the following reagents per litre deionised water:
1 mL of the FeCl3 .6H2O solution
1 mL of the MgSO4.7H2O solution
1 mL of the CaCl2.2H2O solution
10 mL of the phosphate solution
- Test temperature: 20 ± 1 °C
- pH: pH of the test solutions at the end of the test was 7.0-7.8
- pH adjusted: No
- Suspended solids concentration: 28 mg/L

TEST SYSTEM
- Culturing apparatus: Borosilicate glass Erlenmeyers (500 mL)
- Number of culture flasks/concentration: Two
- Method used to create aerobic conditions: Oxygen was generated by a pressure sensitive electrolytic oxygen generator by passage of a constant current (100 mA for 20 s) through the sulphuric acid/copper solution. This oxygen was then supplied to the incubation flask.
- Measuring equipment: Oxygen demand of each test sample was continuously measured using the Sapromat apparatus (Voith GmBh, Heidenheim, FRG)
- Details of trap for CO2 if used: CO2 produced was absorbed by sodalime pellets

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, containing mixed liquor and dilution water
- Procedure control: Yes, containing reference substance (aniline) with inoculated medium

Reference substance

Reference substance:

aniline

Remarks:

100 mg/L

Results and discussion

Preliminary study:

No data

Test performance:

No data

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

88

Sampling time:

28 d

Remarks on result:

other: Initial concentration of the test material: 50 mg/L

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

91

Sampling time:

28 d

Remarks on result:

other: Initial concentration of the test material: 100 mg/L

Details on results:

Initial test material concentration: 50 mg/L
- Oxygen uptake = 58 mg O2/L
- Intrinsic biochemical oxygen demand, BODi = 1.16 mg O2/mg test substance
- % biodegradation on Day 5: > 10%
- % biodegradation on Day 6: > 60%
- % biodegradation on Day 28 = 88%

Initial test material concentration: 100 mg/L
- Oxygen uptake = 119.5 mg O2/L
- Intrinsic biochemical oxygen demand, BODi = 1.195 mg O2/mg test substance
- % biodegradation on Day 6: > 10%
- % biodegradation on Day 9: > 60%
- % biodegradation on Day 28 = 91%

BOD5 / COD results

Results with reference substance:

- Oxygen uptake = 230 mg O2/L
- Intrinsic biochemical oxygen demand, BODi = 2.30 mg O2/mg aniline
- ThOD = 3.01 mg O2/mg
- % biodegradation (Day 7) > 60%
- % biodegradation (Day 28) = 76%

Any other information on results incl. tables

None

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

% degradation in reference material reached the pass levels by Day 14; oxygen uptake of inoculum blank was 8 mg O2/L; pH of the test solutions at the end of the test was 7.0-7.8. Toxicity control was not performed. However, the study “Activated sludge Re

Interpretation of results:

readily biodegradable

Conclusions:

Under the test conditions, ALIMET was readily biodegradable.

Executive summary:

A study was conducted to determine the ready biodegradability of alimet in an aerobic aqueous medium similarly to OECD Guideline 301 F and in compliance with GLP. The substance was tested at concentrations of 50 and 100 mg/L and the inoculum was activated sewage sludge, domestic. The degradation of the test material was assessed by the determination of the amount of oxygen consumed. The test treatments, inoculum blank and the reference (aniline) were measured in duplicates.

At 50 mg/L test concentration, greater than 10% biodegradation of the test substance was reached on Day 5 and greater than 60% biodegradation was reached on Day 6. Hence, the test material met the 10 day window requirement for ready biodegradability. On Days 28, the biodegradation was 88%.

 

At 100 mg/L test concentration, greater than 10% biodegradation of the test substance was reached on Day 6 and greater than 60% biodegradation was reached on Day 9. Hence, the test material met the 10 day window requirement for ready biodegradability. On Days 28, the biodegradation was 91%.

 

The reference material, aniline, reached greater than 10% biodegradation on Day 4 and greater than 60% on Day 7. Hence, it met the validity criteria for a reference material. Oxygen uptake of inoculum blank was 8 mg O2/L and pH of the test solutions at the end of the test was 7.0-7.8.

 

Under the test conditions, ALIMET was readily biodegradable.