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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

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biodegradation in water: ready biodegradability
Type of information:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
The complete read across justification is detailed in section 13. Test substance is an isomer of the substance under registration; structural difference is not expected to significantly impact biodegradation potential. Source study has reliability 2: only limited information available from a migrated NONS file, as per Article 25(3) request.
according to guideline
other: C.8 / C.9
Principles of method if other than guideline:
No available information on the method used.
GLP compliance:
not specified
Oxygen conditions:
Inoculum or test system:
not specified
Duration of test (contact time):
ca. 5 d
Remarks on result:
other: BOD5/COD
ca. 5

BOD5/COD = 0.05

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
BOD5/COD = 0.05
non readily biodegradable
Executive summary:


Test conducted according to EU method C.8 and C.9. No details on the method are available. The information derived from migrated NONS file, as per Article 25(3) request, with permission to refer granted by ECHA.



BOD5/COD =0.05.

Not readily biodegradable.

Description of key information

Non readily biodegradable.

Key value for chemical safety assessment

Additional information

Direct Blue 273 is a dyestuff. Based on its function and chemical nature, it is not expected to be readily biodegradable.

Due to the lack of data on Direct Blue 273, a read across approach was followed. A screening test of biodegradation was available on Similar Substance 01, i.e. an isomer of Direct Blue 273, differing only for the position of a functional group on an aromatic ring. Further details on the read across approach are included in section 13.

In a screening test on Similar Substance 01, Biochemical Oxygen Demand (BOD) and the Chemical Oxygen Demand (COD) were measured following EU method C.8 and C.9.

Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for determining this amount. This is not a precise quantitative test, although it is widely used as an indication of the organic quality of water, thus it should not be used as quantitative data about ready biodegradation.

As reported in ECHA Guidance 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."

The only data available are measures of BOD5, COD and their ratio. According to the ECHA "Guidance on information requirements and chemical safety assessment - Chapter R.7b: Endpoint specific guidance" (May 2008 version 1.1), if the BOD5:COD ratio is lower than 0.5, it can be expected that the substance is not readily biodegradable; if the ratio between BOD5 and COD is more than 0.5 there is an indication of ready biodegradation.

Based on a BOD5/COD ratio lower than 0.5, the substance is expected to be non readily biodegradable.

Relying on a read-across approach, Direct Blue 273 is considered as non readily biodegradable.