Disodium [N-[7-hydroxy-8-[(2-hydroxy-5-mesylphenyl)azo]-1-naphthyl]acetamidato(2-)][2-hydroxy-3-[(2-hydroxy-1-naphthyl)azo]-5-nitrobenzenesulphonato(3-)]chromate(2-)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: inherent biodegradability

Remarks:

Evaluation of inherent biodegration and COD/BOD5

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

Justification for read across is detailed in the report attached to the IUCLID section 13.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

yes

Remarks:

The test substance was running in duplicate instead in triplicate.

Principles of method if other than guideline:

None

GLP compliance:

yes

Specific details on test material used for the study:

None

Oxygen conditions:

aerobic

Inoculum or test system:

other: Mixture of polyvalent bacteria collected on February 13, 1996 in the aeration tank of a domestic sewage treatment plant, PRO RHENO Basel communal

Details on inoculum:

Test organismStrain / Inoculation Mixture of polyvalent bacteria collected on February 13, 1996 in the aeration tank of a domestic sewage treatment plant, PRO RHENO Basel communal.Bacteria concentration : 100 mg/l suspended solids

Duration of test (contact time):

28 d

Details on study design:

This test method was based on the following conditions:- test chemicals as sole organic carbon sources- no adaptation of micro-organisms to the test chemicalsTested chemicals were inoculated in the testing vessels with micro-organisms. During the test period, the Biochemical Oxygen Demand was measured continuousily by means of a BOD-meter. Biodegradability was calculated on the basis of the theoretical oxygen demand (ThOD) or less satisfactorily COD, if the ThOD could not be calculated.Optionally, primary biodégradation could be determinated by analysis of dissolved organic carbon (DOC) at the beginning and the end of the test.

Reference substance:

benzoic acid, sodium salt

Remarks:

[Merck No. 6290]

Preliminary study:

None

Key result

Parameter:

% degradation (test mat. analysis)

Value:

0

Sampling time:

28 d

Remarks on result:

other: Standard deviation is not available

Details on results:

None

Results with reference substance:

Biodegradation after 28 days of the reference substance was 88 %

None

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Biodegradation of the test substance after 28 days was 0 %.

Executive summary:

A key study was performed to determine the percent biodegradation. An inherent biodegradability te Similar subsyance was determined in a 28 days MITI (II) - Test according to the OECD Guideline for Testing of Chemicals, No. 302C. The test substance was tested in a concentration of 30 mg/l. The reference substance (Sodium benzoate) was tested in a concentration of 100 mg/l. Based on the results of the study, biodegradation of the test substance after 28 days was 0 %.

Description of key information

Not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

BIOWIN estimates the probability of rapid aerobic and anaerobic biodegradation of an organic compound in the presence of mixed populations of environmental microorganisms.  BIOWIN contains seven separate models. According to Ready Biodegradability Prediction outcome, the substance is considered no readily biodegradable.

Similar substance 01 and was evaluated for biodegradability.

A key study was performed to determine the percent biodegradation of Similar substance 01. An inherent biodegradability was determined in a 28 days MITI (II) - Test according to the OECD Guideline for Testing of Chemicals, No. 302C. The test substance was tested in a concentration of 30 mg/L. The reference substance (Sodium benzoate) was tested in a concentration of 100 mg/L. Based on the results of the study, biodegradation of the test substance after 28 days was 0 %.

In another key study, chemical oxygen demand COD was calculated according to DIN 38409 - H 41-1 (1980) corresponding to EEC Directive 92/69/C.6 (1992). The test substance 01 was tested with a sample weight of 3.53 and 3.76 mg. The reference substance was Potassium hydrogen phthalate. It was tested with 20 mL of a 0.17 g/L solution. The COD of the Similar substance 01 was found to be 824 mg 02/g.

A supporting study was performed to determine the biochemical oxygen demand of the Similar substance 01, by measuring the dissolved oxygen concentration before and after 5 days incubation at 20 °C. Based on the findings from the study, the BOD5 was found to be 19.0 mg O2/g test mat.

Several data on BOD5 and COD are also available on Similar substance 02.

The data Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) are the most commonly used parameters for the characterization of the biodegradability capacity. COD results are typically higher than BOD5 values, and the ratio vary depending on the characteristics of the substrate. This ratio has been commonly used as an indicator for biodegradation capacity, the "Biodegradability index" (B.I.).

As indicated in ECHA Guidance Requirement R.7B, the BOD5 test is a traditional biodegradation test that is now replaced by the ready biodegradability tests. Therefore, this test should not be performed today for assessment of the ready biodegradability of substances. Older test data may, however, be used when no other degradability data are available. If the ratio BOD5/COD is => 0.5, the substance is regarded as being readily biodegradable.

The ratio BOD5/COD of the found BOD5 and COD values is less than 0.5 (if => 0.5, the substance is regarded as being readily biodegradable), therefore the substances showed no ready biodegradability.

Additionally, by the nature of their design and use, acid dyes are not intended to be readily biodegradable as this would assist in the rapid destruction of the dyestuff, rendering it unfit for purpose. As such, it is accepted that such substances are not readily biodegradable under relevant environmental conditions. A published study (Pagga & Brown, 1986) describes the results of the testing of 87 dyestuffs in short-term aerobic biodegradation tests. The authors of this publication concluded that dyestuffs are very unlikely to show any significant biodegradation in such tests and that 'there seems little point in carrying out such test procedures’ on dyestuffs. There are ISO, European, American (AATCC) and national standards for the color fastness of dyes. Dyes are required to have specific fastness properties. If the dyes were biodegradable, it would not be possible for them to have these fastness properties.