Disodium 7-amino-4-hydroxy-3-[[4-[(4-sulphonatophenyl)azo]phenyl]azo]naphthalene-2-sulphonate

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:

2000

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:

other: Real Decreto 363/1995 (BOE núm. 133 de Junio de 1995)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Secondary effluent from the Urban Water Treatment Plant in Manresa (Spain)
No further details on inoculum given in the study report.

Duration of test (contact time):

28 d

Initial conc.:

5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
Solution 1:
KH2PO4 8.5 g/L H2O
K2HPO4 21.75 g/L H2O
Na2HPO4 2H2O 33.4g /L H2O
NH4Cl 0.5 g/L H2O
Solution 2: CaCl 2 2H2O 36.4 g/L H2O
Solution 3: MgSO 47H2O 22.5 g /L H2O
Solution 4: FeCl3 6H2O 0.25 g/L H2O
Add to 1000 mL of deionized water:
Solution 1 1 mL
Solution 2 1 mL
Solution 3 1 mL
Solution 4 1 mL
- Test temperature: 20 ± 2 ºC
- pH: not specified
- Aeration of dilution water: not specified
- Suspended solids concentration: not specified
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: Erlenmeyer flasks (100 ml) with a cap, fully filled
- Number of culture flasks/concentration: 2
- Measuring equipment: not specified
- Details of trap for CO2 and volatile organics if used: not specified
- Other:
Preparation of stock and test solutions: A stock solution having a concentration of 1 g/L of the material presented (ref: Red P / Paper 8BLP (batch: PAL-025777)) was prepared. Therefore, 0.1 g of the presented material has been dissolved in 100 mL of water in a 100 mL Class A volumetric flask by shaking, so we have a stock solution of 1000 mg / L. To prepare the solution to be tested (5 mg / L), 10 mL of stock solution was diluted in 2 liters of inoculated culture medium.
The test containers have been filled with the solution to overflow, so that no bubbles of air remain inside the bottle.

Concentrations per test: 1 + substance for reference + blank

SAMPLING
- Sampling frequency: at day 0, 3, 7, 10, 14, 21, 28 (Number of measurements: 7)
- Sampling method: not specified
- Sterility check if applicable: not specified

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: not specified
- Toxicity control: not specified

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

0 h

Parameter:

% degradation (O2 consumption)

Value:

0.9

Sampling time:

3 d

Parameter:

% degradation (O2 consumption)

Value:

2.3

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

6

Sampling time:

10 d

Parameter:

% degradation (O2 consumption)

Value:

11.1

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

13.7

Sampling time:

21 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

18

Sampling time:

28 d

Parameter:

COD

Value:

1.74 g O2/g test mat.

Results with reference substance:

Sodium acetate: 0,68 mg O2/mg

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The result obtained in this study indicates that the test item has a biodegradability of 18% at the initial concentration tested (5 mg / L) at 28 days of testing.

Executive summary:

The determination of the biodegradability has been carried out after 28 days for the test substance DR 254 TEA salt following the OECD Guideline 301D (closed bottle test) (1992) together with the Spanish Royal Decree 363/1995 (BOE No. 133 of June 1995).
Biodegradation is defined as the decomposition of an organic compound by the biological action of microorganisms, which results in the disappearance of the original molecular structure and the formation of smaller organic molecules.The results are expressed as the percentage of biodegradation after 28 days.

Starting from a known concentration of the test substance (5 mg / L), monitoring is carried out by measuring the oxygen consumption at intervals of time over a period of 28 days.

Description of key information

There is one study available for the substance with CAS 64 683 -40 -5 (Direct Red 254 TEA salt) done according to the OECD 301D (readily biodegradability). This substance has the identical chemical molecular structure in respect to the anionic organic components than the substance with CAS 6300 -50 -1 (Direct Red 254 Na salt).

The study of biodegradation in water assigned as Key Study is the one conducted according to OECD guideline 301D on the substance with CAS 64 683 -40 -5 (Direct Red 254 TEA salt).

The result of 18 % of degradation after 28 days (< 60%), based on the oxygen consumption shows that the substance can not be classified as ready biodegradable.

Both substances CAS 64 683 -40 -5 (Direct Red 254 TEA salt) and CAS 6300 -50 -1 (Direct Red 254 Na salt) have the same anionic structure. This is expected the same biodegradability concerning this organic part.

Whereas the counterion of the substance CAS 6300 -50 -1 (Direct Red 254 Na salt) is the sodium, the one of the substance with CAS 64 683 -40 -5 (Direct Red 254 TEA salt) is the triethanolamine, which is susceptible to be biodegraded too. If the determined biodegradability of this substance, that has a greater contribution of organic structures to be degraded, is so low (18%) it is not expected that the substance with CAS 6300 -50 -1 (Direct Red 254 Na salt) could have a higher degree of biodegradation. Therefore, it is justified to consider that the substance with CAS 6300 -50 -1 will have at most the same degree of degradation of the substance with CAS 64683 -40 -5, that means "non readily biodegradable".

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed