Suberic acid

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:

2018-07-02 - 2018-08-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Suberic acid

EC Number:

208-010-9

EC Name:

Suberic acid

Cas Number:

505-48-6

Molecular formula:

C8H14O4

IUPAC Name:

octanedioic acid

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Name 1,8-Octanedioic acid / SUBERIC ACID
Appearance White crystalline powder
Composition Suberic acid 100 %
CAS No. 505-48-6
EINECS-No. 208-010-9
Molecular formula C8H14O4
Molecular weight 174.20 g/mol
Purity 100% by GC

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Specification
Activated sludge from a biologic sewage treatment plant was used as inoculum. The cho-sen plant treats mostly domestic sewage.
Source and Pre-Treatment of inoculum
Source
The sludge was taken from the activation basin of the sewage treatment plant, In den Seewiesen, 67480 Edenkoben.
Date of collection: 29. Jun. 2018, batch no: 20180629.
Pre-Treatment
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4060 mg of sus-pended solids/L.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, mois-tened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.
Magnetic stirrers were used to prevent deposition of inoculum.
The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels. The initial IC value of the 0.25 M NaOH was separately determined in each flask.
Sampling
From each front scrubber flask, 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL. The re-sulting change in the volume of the front flask was considered in the calculation of emitted CO2.
On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.
CO2 Determination
Analyses of the emitted CO2 were made by IC measurement using the carbon analyser TOC multi N/C 2100S, Analytik Jena. Each sample was measured in duplicate or triplicate, respectively (depending on the variation between the measured values). The carbon analyser was calibrated with freshly prepared reference solutions containing potassium hydrogen phthalate (TC), sodium hydrogen carbonate and sodium carbonate (IC) every month. After every start, quality control samples were measured.

Reference substance

Reference substance:

aniline

Results and discussion

% Degradation

% Degradation 1

Key result

Parameter:

% degradation (CO2 evolution)

Value:

9.6

Sampling time:

2 d

% Degradation 2

Key result

Parameter:

% degradation (CO2 evolution)

Value:

66.8

Sampling time:

7 d

% Degradation 3

Key result

Parameter:

% degradation (CO2 evolution)

Value:

78.5

Sampling time:

18 d

% Degradation 4

Key result

Parameter:

% degradation (CO2 evolution)

Value:

85.4

Sampling time:

29 d

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Ready biodegradability is defined in the guidelines as degradation surpassing 60% within 10 days after reaching a level of 10 %. Therefore, the test item 1,8-Octanedioic acid / SUBERIC ACID can be considered as “readily biodegradable”.

Executive summary:

The test item1,8-Octanedioic acid / SUBERIC ACIDwas tested using a concentration of nominally 20 mg organic carbon/L1,8-Octanedioic acid / SUBERIC ACIDin test medium following OECD 301B and EU-Method C.4-C.

 

Aniline was chosen as positive control.

Activated sludge was used as inoculum (concentration in the test 25.0 mg dry matter/L). The test was left running for 28 days.

All validity criteria were met. Degradation of the positive control surpassed the pass level of 60 % after 9 days.

 

The following data were determined for the test item1,8-Octanedioic acid / SUBERIC ACID:

10-day-window:                                                                                                                  day 2– 12
degradation at the end of 10-day-window                                                                             78 %
degradation at the end of the test                                                                                            85 %
pass level following guideline:       60 % at the end of 10-day-window for pure substances respective 60 % at the end of the test for mixtures

Therefore, when applying the 10-day-window,1,8-Octanedioic acid / SUBERIC ACID is readily biodegradable following OECD 301B and EU C.4-C respectively.