Diethyl maleate

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:

22 March 2004 to 27 July 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Diethyl maleate

EC Number:

205-451-9

EC Name:

Diethyl maleate

Cas Number:

141-05-9

Molecular formula:

C8H12O4

IUPAC Name:

diethyl (Z)-but-2-enedioate

Details on test material:

- Name of test material (as cited in study report): DIETHYLMALEINATE
- Physical state: Colourless liquid.
- Batch No.: ETLM 201.
- Expiration date of the lot/batch: 30 June 2005.
- Stability under test conditions: Stability in aqueous solution: stable
- Storage condition of test material: Room temperature, in the dark, may be used under light.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge was collected from a sewage treatment works A-2500 Baden, which waste-water catchment is predominantly domestic. On arrival in the laboratory, the sample was aerated by means of a filtered compressed air before being used for the study.
The suspended solids concentration was determined by filtering a 5 mL sample through a pre-dried and pre-weighed glass filter (Whatman GF/C). The filter with solids were dried at 105 °C and re-weighed and the sludge solids determined by difference.
The inoculum was not acclimatised or adapted to "DIETHYLMALEINATE" before exposure to the test substance in this study. The concentration of the final suspended solids of the sludge in all vessels was nominally 20 mg/L.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

27 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

15 mg/L

Based on:

other: Carbon

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium as described in the guideline.
- Additional substrate: none.
- Solubilising agent (type and concentration if used): none.
- Test temperature: 22.1 +- 0.4 °C.
- pH: determined, for details see aditional background material: Key. Weiss Fuchs 2004. Carbon Dioxide Evolution Test for Ready Biodegradability Tables and figures.pdf
- pH adjusted: no
- Suspended solids concentration: 20 mg/L.
- Continuous darkness: yes.

TEST SYSTEM
- Culturing apparatus: 5 L flasks.
- Number of culture flasks/concentration: 2 negative control flasks, 2 test substance flasks, 1 positive control flask, 1 toxicity control flask.
- Method used to create aerobic conditions: Apparatus for carbon dioxide scrubbing and a mixture of CO2-free oxygen and CO2-free nitrogen, from gas cylinders, in the correct proportions (20 % O2: 80 % N2) were used.
- Test performed in closed vessels.

SAMPLING
- Sampling frequency: The CO2 evolution was determined on Days 1, 2, 4, 6, 8, 10, 15, 20, 25 and 28/29.
Day 0 was the day of the addition of the test substance to the medium.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes, containing test substance and positive reference substance.
- Other: Positive reference substance.

STATISTICAL METHODS: no.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Preliminary study:

None.

Test performance:

No unusual observations were made.

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

60.1

Sampling time:

8 d

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

96.7

Sampling time:

28 d

Details on results:

In this Carbon Dioxide Evolution Test the biodegradation of "DIETHYLMALEINATE" was 93.7 % and 99.6 % with a mean of 96.7 % after 28 days. The "10-d window" as defined by the guidelines started on approx. Day 3. 60 % degradation was exceeded on approximately Day 8.
For more details please see aditional background material: Key. Weiss Fuchs 2004. Carbon Dioxide Evolution Test for Ready Biodegradability Tables and figures.pdf.

BOD5 / COD results

Results with reference substance:

Positive control: 73.7% biodegradation after 10 days. The plateau of biodegradation was reached on about Day 10 and the degradation of the positive control substance sodium benzoate reached the pass level of 60 % on Day 6. The test is considered to be valid.
Toxicity control: 80.8 % biodegradation after 28 days. Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The ready biodegradability of "DIETHYLMALEINATE" was determined by the measurement of carbon dioxide evolution at frequent intervals over a 28 d period. The method used was that described in Part C.4-C of the EC Commission Directive 92/69/EEC and in the OECD Guideline 301B.

Results:
The reference substance sodium benzoate was degraded by 73.7 % within 10 days.
Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance.
The test substance "DIETHYLMALEINATE" was degraded by 96.7 % after 28 days of incubation. The "10-d window" as defined by the Guideline started at approx. Day 3. 60 % degradation was exceeded already at Day 8.

Classification
According to the Guidelines a substance giving a result greater than 60 % degradation in a 10 day window within 28 days is regarded as "readily biodegradable".
According to the results of this study, "DIETHYLMALEINATE" can therefore be classified as readily biodegradable.

Executive summary:

The ready biodegradability of "DIETHYLMALEINATE" was determined by the measurement of carbon dioxide evolution at frequent intervals over a 28 d period. The method used was that described in Part C.4-C of the EC Commission Directive 92/69/EEC and in the OECD Guideline 301B.

Results:

The reference substance sodium benzoate was degraded by 73.7 % within 10 days.

Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance.

The test substance "DIETHYLMALEINATE" was degraded by 96.7 % after 28 days of incubation. The "10-d window" as defined by the Guideline started at approx. Day 3. 60 % degradation was exceeded already at Day 8.

Classification

According to the Guidelines a substance giving a result greater than 60 % degradation in a 10 day window within 28 days is regarded as "readily biodegradable".

According to the results of this study, "DIETHYLMALEINATE" can therefore be classified as readily biodegradable.