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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2012-08-15 to 2012-09-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP Guideline study, no deficiencies

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2013

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Deviations:
yes
Principles of method if other than guideline:
The ratio of test compound to inoculum dry weight was 1:6.7 instead of 1:2.5 to 1:4.
The room temperature was temporarily under 20°C.
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Tripropenyl succinic acid
Cas Number:
147384-84-7
Molecular formula:
R-C4H6O4 , whereas R=C8-C10-alkyl-(branched, unsaturated)
IUPAC Name:
Tripropenyl succinic acid
Details on test material:
- Name of test material (as cited in study report): Tripropenyl succinic acid
- Physical state: Viscous liquid, pale brown
- Analytical purity: 99.3 %
- Purity test date: 2013-03-04
- Lot/batch No.: 12-SK002
- Expiration date of the lot/batch: January 2014
- Stability under test conditions: Not applicable
- Storage condition of test material: Room temperature, protected from light, in original container

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the sewage plant at 31137 Hildesheim is well suited as it receives predominantly municipal sewage and hardly any industrial chemical waste.

- Preparation of inoculum for exposure: The activated sludge was washed twice with autoclaved tap water. The dry sludge concentration was determined and an appropriate volume of inoculum was chosen to get a dry sludge concentration of 0.2 - 1.0 g/L in the test vessels and a ratio of DOC of test compound / inoculum in the range of 1:2.4 - 1:4
- Dry sludge concentration of inoculum: 3.01 g/L
- Water filtered: no
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
40 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral salts medium acc. to OECD 302 B
- Additional substrate: No
- Test temperature: 20-25 °C
- pH: please refer to the respective table
- pH adjusted: no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 2000 mL test vessels
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Permanent aeration
- Measuring equipment: The inherent biodegradation was monitored by determination of DOC according to Guideline DIN EN 1484. Samples were taken at the beginning of the test (0h, 3h) and after 2, 7, 13, 21 and 28 days. The pH was measured after every sampling point. The temperature was measured on every sampling day in one replicate.



SAMPLING
- Sampling frequency: Samples were taken at the beginning of the test (0h, 3h) and after 2, 7, 13, 21 and 28 days.


CONTROL AND BLANK SYSTEM
- Inoculum blank: Test item in test concentration without inoculum, poisoned with 10 mL/L of 10 g/L HgCl2 solution.
- Abiotic sterile control: No
- Toxicity control: Test item and reference item in test concentrations



STATISTICAL METHODS:
The inherent biodegradation was monitored by determination of DOC in filtered samples taken at seven sampling points.
The ratio of eliminated DOC, corrected for the inoculum control at each time interval to the initial DOC (0h) value is expressed as the percentage biodegradation at the sampling time.
Reference substance
Reference substance:
diethylene glycol

Results and discussion

Preliminary study:
No preliminary study
Test performance:
The test item was added at a test concentration of 40 mg/L, corresponding to a theoretical carbon content of 29.8 mg C/L in the test vessels.

The following incubation vessels were prepared:

- two for the test item (P1, P2)
- one for the functional control (R1)
- two for the inoculum control (C1, C2)
- one for the sterile control (B1)

Stock solutions of test and reference item were prepared. Appropriate volumes of the stock solutions, mineral salts medium and inoculum were filled in a measuring flask. 2000 mL of this solution were placed in each test vessel.

The pH in every test vessel was in the range of 6.5 - 8.0, adjustment was not necessary.

The incubation vessels were aerated and stirred continuously on a magnetic stirrer.

The biodegradation was monitored by determination of DOC in filtered samples taken at regular time intervals.
% Degradation
Parameter:
% degradation (DOC removal)
Value:
5
Sampling time:
28 d
Details on results:
The physico-chemical elimination of the test item was checked in the sterile control at the test item concentration of 40 mg/L (without inoculum and poisoned with HgCl2). No physico-chemical elimination occurred in the sterile control after 28 days.

Related to the initial determined DOC concentration (0 h) the test item reached the 10 % level (beginning of biodegradation) after 13 days. The biodegradation remained in the range of 0-18 % and the level of 70 % was not reached within the test duration of 28 days. After 28 days a biodegradation of 5 % was determined.

The test item is classified as not inherent biodegradable within 28 days.

BOD5 / COD results

Results with reference substance:
The adaptation phase of the functional control changed after 3 days into the degradation phase (degradation  10 %). The course of the degradation phase was rapid and the pass level of 70 % was reached within 6 days. After 13 days a biodegradation of 100 % was reached. The validity criterion degradation  70 % after 14 d is fulfilled.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not inherently biodegradable
Conclusions:
The test item is under the test conditions chosen not inherent biodegradable within 28 days.

Executive summary:

The inherent biodegradability of the test item Tripropenyl succinic acid (batch number 12-SK002) was determined in the Zahn-Wellens-Test / EMPA Test with a non adapted activated sludge over a period of 28 days. The definitive study was conducted from 2012-08-15 to
2012-09-12
according to OECD guideline 302 B at Dr.U.Noack-Laboratorien,D-31157 Sarstedt.
The test item was tested at a concentration of
40 mg/L in duplicates, corresponding to a DOC of 29.8 mgC/L in the test vessel. The biodegradation of the test item was followed by determination of DOC in filtered samples. The ratio DOC to activated sludge dry weight at the beginning was 1:6.7. The ratio of eliminated DOC, corrected for the inoculum control to the initial DOC value is expressed as the percentage biodegradation at each sampling date.

In order to check the activity of the test system diethylene glycole at a concentration of 120 mg/L was used as functional control. After 7 days a biodegradation rate of 99 % was reached.

The physico-chemical elimination of the test item was checked in the sterile control (without inoculum and poisoned with HgCl2) at the test item concentration of 40 mg/L. No physico-chemical elimination occurred in the sterile control after 28 days.

The inherent biodegradation of the test item is shown in Table 1and graphically indicated in Figure 1 in comparison to the inherently degradable functional control and the elimination in the sterile control. The biodegradation reached the 10 % level (beginning of biodegradation) after 13 days. The biodegradation remained in the range of 0-18 % and the level of 70 % was not reached within the test duration of 28 days. After 28 days a biodegradation of 5 % was determined.

According to the criteria of the OECD 302B guideline the test item is
not inherently biodegradablewithin 28 days.

Inherent Biodegradability of the Test Item Tripropenyl succinic acidin
                   Comparison to the Functional Control and Sterile Control

Inherent Biodegradation / Elimination [%]

Study Day [d]

0 (3h)

2

7

13

21

28

Test Item

0 (0)

2

8

18

0

5

Functional Control

0 (1)

4

99

100

100

100

Sterile Control*

0 (0)

0

0

0

0

0