Disodium sebacate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Duration of test (contact time):

28 d

Initial conc.:

2.64 mg/L

Based on:

test mat.

Initial conc.:

5.02 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

This seawater had a salinity of 34.5 per mil. Prior to use the seawater was decanted to remove coarse particles and aged under aerobic conditions at room temperature for about 7 days.

- To prevent possible oxygen consumption by nitrification processes, a nitrification inhibitor (allylthiourea) was added to the test system.
- The temperature was 19.7 - 20.4 °C, and dissolved oxygen in the water of the test flasks was determined weekly.
- The test substance was poorly soluble in water.
Glass fibre filters were used as an inert carrier for the test substance, and the test substance was applied to the filters as a stock solution in aceton. 80.1 mg of the test substance was dissolved in 10 mL of acetone. 100 µL of the solution was applied to the filters. For one hour the solvent was dried off and the filters were added to the test system.
- The possible inhibition of bacterial growth was tested in bottles containing a mixture of test substance and reference substance. The test substance was added at the same concentration as when tested alone (2.64 mg/L) and the reference substance was added in half the concentration 1.25 mg/L.
- Sets of BOD bottles were filled with test solutions: 11 bottles containing the test substance, 9 bottles containing the reference substance, and
5 bottles containing the inhibition control mixture. In addition 11 bottles were filled with the enriched seawater, containing neither test substance
nor reference substance, to serve as blanks. Filters treated with acetone only were added to the blanks.

TEST CONDITIONS
- Composition of medium: Natural seawater from an unpolluted site at about 80 m depth in Byfjord was collected from a tap at Akvamiljo.
- Additional substrate: Nutrients were added to the test system as described in the OECD Guideline 306.
- Solubilising agent: Acetone,
- Test temperature: 19.7 - 20.4 °C
- Suspended solids concentration: 8.01 mg/mL

TEST SYSTEM
- Culturing apparatus: BOD bottles
- Number of culture flasks/concentration: 11 bottles containing the test substance, 9 bottles containing the reference substance, and 5 bottles containing the inhibition control mixture. In addition 11 bottles were filled with the enriched seawater, containing neither test substance nor reference substance, to serve as blanks. Filters treated with acetone only were added to the blanks.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

89

Sampling time:

28 d

Results with reference substance:

83 % oxidation of sodium benzoate

Interpretation of results:

readily biodegradable

Reference 2

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:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: effluent of the sewage treatment plant Edenkoben (28.11.1989)
- Concentration of sludge: 0.5 g/L

Duration of test (contact time):

7 d

Initial conc.:

23 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

SAMPLING
- Sampling frequency: day 0, 1, 3, 7

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
- Other: control batch (HgCl2), inhibition batch

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (DOC removal)

Value:

98

Sampling time:

7 d

Details on results:

Kinetic of test substance (in %):
= 0 after 0 day(s)
= 14 after 1 day(s)
= 97 after 3 day(s)
= 98 after 7 day(s)
Degradation products: not measured

Results with reference substance:

Kinetic of control substance (in %):
= 95 after 3 day(s)
= 96 after 7 day(s)

Interpretation of results:

readily biodegradable

Description of key information

The test substance is readily biodegradable in sea- and freshwater (BASF SE,1990; BASF SE, 2009).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Disodium sebacate is well soluble in water. The dissociation product sebacic acid (CAS 111 -20 -6) is readily biodegradable. In a DOC removal test similar to OECD 301 E, the biodegradation of sebacic acid in freshwater was investigated (BASF SE, 1990). After 7 days a degradation of 98 % was determined. Additionally, a study on biodegradation of sebacic acid in seawater was conducted according to OECD 306 (BASF SE, 2009). The biodegradation was 89 % after 28 days. This result also confirms the outcome of the freshwater study. According to ECHA Guidance R7b data of the anion can be used if no data on salt is available. As biodegradability criteria and testing are not applicable for inorganic substances as sodium, it can be stated that the substance CAS 17265 -14 -4 is readily biodegradable.