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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

non-readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

No data is available on the substance itself, thus the assessement of the biodegradation potential of the target substance is done by using the Read Across approach. The justification for Read Across is given in section 13 of IUCLID.

Two biodegradation tests (BOD5/COD) perfomed under GLP conditions are available for Similar Substance 01.

The first study [Huntsman Textile Effects (Germany) GmbH, 1992] was performed according to ISO 5815. The test substance was incubated with seeding water of an urban waste water at concetrations ranging between 806.9 and 6.3 mg/l for 5 days at 20 °C. The BOD5 of the test substance was determined to be 4 mg O2/g.

The second study [Huntsman Textile Effects (Germany) GmbH, 1991], was performed following the EU Method C.6 ( EEC Directive 84/449). The test substance was chemically oxidised with potassium dichromate at 148 °C for 2h. The amount of unreacted potassium dichromate was determined by titration. The COD was calculated as 1384 mg O2/g.

According to ECHA guidance r7b (version 4.0, June 2017), in addition to the OECD methods, there is a surrogate procedure whereby if the BOD5:COD ratio is 0.5 or higher, the substance is regarded as being readily biodegradable. In the case of the Similar Substance 01, the same lot no was used in the two tests therefore the BOD5:COD can be calculated for the substance. The BOD5:COD is equal to 0.003 suggesting that the substance is not expected to be readily biodegradable.

This expectation is confirmed by the data set (attached) on other similar substances which have a different salification from the Target Substance.

The studies selected as the most representative and conservative were performed on Similar Substance 01. The two tests were conducted under GLP conditions and according to standard methods (ISO5815 and EU Method C.6). Other studies available on the other similar substances were not described in detail and were not used as the studies for the assessment of biodegradation potential.