5-[(4-carboxybutanoyl)peroxy]-5-oxopentanoic acid

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of activated sludge: Microorganisms from a domestic wastewater treatment plant (ARA Ergolz II, Fullinsdorf/Switzerland)
- Conditioning: The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. This procedure was repeated twice. Two aliquots of the final sludge suspension were weighed, dried and the mean ratio of wet sludge to its dry weight determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3 g dry material per liter were mixed with test medium and then aerated until use.
- Inoculation: At the start of the test an exact volume of 0.7 mL sludge (filtered through cotton wool) was added per 1000 mL final test medium.

Duration of test (contact time):

28 d

Initial conc.:

4.3 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The test medium was prepared according to the testing guidelines.
- Additional substrate: no
- Test temperature: 21 °C
- Oxygen concentration: 8.3-8.4 mg O2/L
- pH: 7.0 - 7.3
- pH adjusted: no
- Aeration of dilution water: yes
- Suspended solids concentration: 3g/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: wide-necked reagent bottles (with conical shoulder)
- Number of culture flasks/concentration: 16
- Method used to create aerobic conditions: aeration
- Measuring equipment: O2-electrode WTW OXI 539 meter (Wissenschaftlich Technische Werkstatten, Weilheim/Germany)
- Test performed in open system: no, tightly stoppered

SAMPLING
- Sampling frequency: on day 0, 2, 5, 7, 9, 14, 21 and 28
- Sampling method: The oxygen concentration was measured in an airtight system
- Sample storage before analysis: no

CONTROL AND BLANK SYSTEM
- Inoculum blank: Inoculum and test medium
- Procedure control: sodium benzoate, inoculum and test medium
- Toxicity control: Test item, sodium benzoate, inoculum and test medium

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

77

St. dev.:

2

Sampling time:

28 d

Details on results:

The BOD levels of the test flasks containing the test item increased during the exposure time from -0.097 to 0.889 mg 02/mg test article. The BOD measured in test flask 1a on day 5 (0.563 mg 02/mg test article) was designated as an outlier. The biodegradation of GAP started after 7 days of incubation (2%). After 9 days the biodegradation reached 40% and continuously increased to 77% after 28 days. The percentage biodegradation reached 60% within the 10-day window. Therefore, the test article can be considered as readily biodegradable under the present test conditions.

Results with reference substance:

The reference substance sodium benzoate was sufficiently degraded. The biodegradation reached in the mean 82% after 14 days, and 86% after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum.
The biodegradation in the toxicity control containing both the test article and the reference substance sodium benzoate reached in the mean 83% within 14 days and 87% at the end of the study after 28 days. Thus, according to the test guidelines the test item can be assumed to be not inhibitory on the activated sludge microorganisms under the present test conditions because degradation was clearly >25% within 14 days.

The results are considered valid since:

- Oxygen depletion in the inoculum control was 0.67 mg O2/L after 28 days, and did not exceed 1.5 mg O2/L over the 28-day exposure period.

- The residual oxygen concentration in the test flasks was > 0.5 mg O2/L at any time.

- The difference of duplicate values for the degradation of the test article was less than 20 % at the end of the test.

- The reference substance sodium benzoate was biodegraded by an average of 82 % within 14 days of exposure.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of the test substance was 77% after 28 days in the test according to OECD 301D. Therefore, the test substance was readily biodegradable in the closed bottle test.

Executive summary:

In order to assess the biotic degradation, a ready biodegradability test was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined in the Closed Bottle test according to OECD 301D and EEC Guidelines, and in compliance with the OECD principles of Good Laboratory Practice. In the biodegradability tests, microorganisms are inoculated into a chemically defined liquid medium containing the test substance as sole carbon and energy source. The test compound is exposed to the inoculum, consisting of relatively low numbers of microorganisms from an activated sludge plant, under aerobic conditions for a period of at least 28 days. The test substance caused no reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum. The biodegradation of the test substance was 77% after 28 days. The percentage biodegradation reached 60 % within the 10-day window. Hence, the test substance was readily biodegradable in the Closed Bottle test (28 days) and should therefore be classified as readily biodegradable. The reference substance, sodium benzoate, was degraded 86 % of its theoretical oxygen demand after 28 days.

Description of key information

The biodegradation of the test substance was 77% after 28 days in the test according to OECD 301D. Therefore, the test substance was readily biodegradable in the closed bottle test.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

In order to assess the biotic degradation, a ready biodegradability test was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined in the Closed Bottle test according to OECD 301D and EEC Guidelines, and in compliance with the OECD principles of Good Laboratory Practice. In the biodegradability tests, microorganisms are inoculated into a chemically defined liquid medium containing the test substance as sole carbon and energy source. The test compound is exposed to the inoculum, consisting of relatively low numbers of microorganisms from an activated sludge plant, under aerobic conditions for a period of at least 28 days. The test substance caused no reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum. The biodegradation of the test substance was 77% after 28 days. The percentage biodegradation reached 60 % within the 10-day window. Hence, the test substance was readily biodegradable in the Closed Bottle test (28 days) and should therefore be classified as readily biodegradable. The reference substance, sodium benzoate, was degraded 86 % of its theoretical oxygen demand after 28 days.