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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Classification & Labelling & PBT assessment

PBT assessment

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Administrative data

PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

Results of screening tests show sulphonated azo substances tend to fail screening (ready biodegradation) studies.   Published literature, including Environmental Hazard Assessment of Azo-colorants by the Danish Environmental Protection Agency Several references found to suggest long term degradation by biotic and abiotic processes.


A number of studies using OECD screening methods have been assessed with a range of 0 – 38% biodegradation. It is likely that the sulphonated azo substances showing higher rates of biodegradation are most likely due to side groups that are more easily metabolised or cleave off the main structure.


The substance is assessed as not ‘B’ based on the high solubility in water and low partition coefficient. In addition, there is no evidence that this class of substance will readily absorb across membranes. The Log Kow is measured to be < -3.0


The substance is not considered ‘T’. Published sources suggest low toxicity to aquatic and marine organisms with acute effects > 100 mg/l and no indication of adverse effects over longer periods.


Review of mammalian toxicity of sulphonated azo substances has found no evidence of CMR or otherwise systemic toxic effects. This class of substance is widely used in food colourants.