Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Additional information

Three different mechanisms for azo dye carcinogenicity have been identified, all involving metabolic activation to reactive electrophilic intermediates that covalently bind DNA:

- Azo dyes that are toxic only after reduction and cleavage of the azo linkage to give aromatic amines, mostly via intestinal anaerobic bacteria. The aromatic amines are metabolically oxidized to reactive electrophilic species that covalently bind DNA.

- Azo dyes with structures containing free aromatic amine groups that can be metabolically oxidized without azo reduction.

- Azo dyes that may be activated via direct oxidation of the azo linkage to highly reactive electrophilic diazonium salts.

Each mechanism may be compound specific, thus azo toxicity is probably caused by more than one mechanism. Therefore it is not possible to predict azo dye carcinogenicity with absolute certainty. Because some species of intestinal anaerobic bacteria (and in some cases, hepatic azo reductases) may reduce any azo compound to aromatic amines, those containing aromatic amine subgroups known to be carcinogenic must be suspect. (Brown, M.A., De Vito, S.C., Predicting azo dye toxicity, Critical Reviews in environmental Science and Technology, Vol. 23, Issue 3, 1993).

In the case of Solvent Red 19E and similar dyes, the azo group can be given off enzymatically in the body and o-toluidine can be formed. o-toluidine has been found to be carcinogenic in animal studies (o-toluidine has a harmonised classified as Carc. 1B with the hazard statement H350).

 

The oral exposure of the substance is not expected as the substance is used by industrial and professional workers. There may be a potential risk of skin cancer from prolonged or repeated skin contact with this product in the absence of good personal hygiene. Occasional skin contact with this product is not expected to have serious effects, but good personal hygiene should be practised and repeated skin contact avoided. This product is classified as skin irritant and skin sensitizer. Personal hygiene measures taken to prevent skin irritation and skin sensitisation are expected to be adequate to prevent undue risk of skin cancer.

Justification for classification or non-classification

In accordance with the criteria for classification as defined in Annex I, Regulation (EC) No 1272/2008, the substance does not require classification with respect to carcinogenicity.There is not sufficient information for classification according to CLP criteria for Category 2; the placing of a substance in Category 2 is done on the basis of evidence obtained from human and/or animal studies, but which is not sufficiently convincing to place the substance in Category 1A or 1B. Such evidence may be derived either from limited evidence of carcinogenicity in human studies or from limited evidence of carcinogenicity in animal studies.

Human and/or animal studies for Solvent Red 19E are not available with regard to carcinogenic potential or metabolism of the substance in the body.