Reaction mass of disodium 3-[(5-chloro-2-phenoxyphenyl)azo]-4-hydroxy-5-[[(p-tolyl)sulphonyl]amino]naphthalene-2,7-disulphonate and 3-[(5-chloro-2-phenoxyphenyl)azo]-4-hydroxy-5-[[(ptolyl)sulphonyl]amino]naphthalene-2,7-disulphonic acid

Biodegradation in water: screening tests

Description of key information

Based on expert judgement and QSAR prediction the substance is not readily biodegradable.

Additional tests for the evaluation of inherent biodegradability and BOD/COD evalutaion of the similar substnace 01 are available:

Inherent biodegradability: the biodegradation of the test substance  after 28 days was 5.3 % while the biodegradation of the reference substance after 8 days was 99.5 %.

COD: 1087 mg/g O2, at concentration of 5 mg/l.

BOD5: 0 mg/g O2, at concentration of 500 mg/L.

BOD5/COD: 0

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Based on expert judgement and QSAR prediction the substance is not readily biodegradable.

Additional tests for the evaluation of inherent biodegradability and BOD/COD evalutaion of the similar substnace 01 are available:

Acid Red 249:1 is a multiconstituent substance composed by the acidic and the sodium salt forms of the same structure (72.7 % and 14.95 % of the substances respectively).

The tests was performed on the major component of the multiconstituent substance. Considering the high similarity between the structures and the composition of the substance the Read Across approach is considered as acceptable. See Section 13.

Inherent biodegradability

The inherent biodegradability was determined in a Zahn-Wellens, test according to the OECD Guideline for Testing of Chemicals, No. 302B, Paris 1992. The test has been performed in compliance with the Procedures and Principles of Good Laboratory Practice (March 1986) issued by the Swiss Federal Department of the Interior recognizing the " OECD Principles of Good Laboratory Practice " Paris, 1981. The test substance and the reference substance Diethylenglycol, respectively, were tested in concentrations of 150 mg/l DOC.

The biodegradation of the test substance after 28 days was 5.3 % while the biodegradation of the reference substance after 8 days was 99.5 %.

BOD5/COD ratio

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 between 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.

Studies on BOD5 and COD are available for this substance, therefore they have been used together with the inherent biodegradability OECD 302.B.

in the weight of evidence approach for this substance.

COD was measured according to Method A-16. Details of the method have been not reported. The COD measured was 1087 mg/g O2, at concentration of 5 mg/l.

BOD5 was measured according to Method A-15. Details of the method have been not reported. The BOD5 measured was 0 mg/g O2, at concentration of 500 mg/l.

The ratio BOD5/COD is 0.

Based on the expert judgement, QSAR prediction and the available data on Similar Substance 01 Acid Red 249:1 is expected to be Not readily biodegradable.