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International Agency for Research on Cancer (IARC) - Summaries & Evaluations

MAGENTA AND CI BASIC RED 9
Manufacture of magenta (Group 1)
CI Basic Red 9 (Group 2B)
Magenta containing CI Basic Red 9 (Group 2B)

For definition of Groups, see Preamble Evaluation.

VOL.: 57 (1993) (p. 215)

Magenta I
CAS No.: 632-99-5
Chem. Abstr. Name: 4-[(4-Aminophenyl)(4-imino-2,5-cyclohexadien-1-ylidene)methyl]-2-
methylbenzenamine, monohydrochloride

Magenta II
CAS No.: 26261-57-4
Chem. Abstr. Name: 4-[(4-Aminophenyl)(4-imino-3-methyl-2,5-cyclohexadien-1-
ylidene)methyl]-2-methylbenzenamine, monohydrochloride

Magenta III
CAS No.: 3248-91-7
Chem. Abstr. Name: 4-[(4-Amino-3-methylphenyl)(4-imino-3-methyl-2,5-cyclohexadien-
1-ylidene)methyl]-2-methylbenzenamine, monohydrochloride

CI Basic Red 9
CAS No.: 569-61-9
Chem. Abstr. Name: 4-[(4-Aminophenyl)(4-imino-2,5-cyclohexadien-1-ylidene)methyl]-
benzenamine, monohydrochloride

5. Summary of Data Reported and Evaluation

5.1 Exposure data

Magenta and CI Basic Red 9, a common constituent of magenta, were first produced commercially in the late nineteenth century in Germany. As the industry developed in the early twentieth century, it converted in some countries, such as Italy and the United Kingdom, from production of magenta (prepared from a mixture of aniline and ortho-toluidine) to production of magenta III (prepared from ortho-toluidine without aniline).

Magenta and CI Basic Red 9 have been used to dye textile fibres, in the preparation of pigments for printing inks and in other specialty applications, such as biological stains.

5.2 Human carcinogenicity data

Two small cohorts of workers engaged in the manufacture of magenta were studied in the United Kingdom and Italy. Marked excesses of cancer of the urinary bladder were identified. Although efforts were made to exclude workers exposed to 2-naphthylamine and benzidine, both cohorts may also have been exposed to aromatic amines present as intermediates and suspected to be urinary bladder carcinogens, such as ortho-toluidine.

5.3 Animal carcinogenicity data

No adequate study was available to evaluate the carcinogenicity in experimental animals of magenta or of magenta I, magenta II or magenta III.

CI Basic Red 9 was tested for carcinogenicity in one study in mice and in one study in rats by oral administration in the diet and in one study in rats by subcutaneous administration. After oral administration, the compound induced hepatocellular carcinomas in male and female mice and in male rats; adrenal gland phaeochromocytomas in female mice; benign and malignant skin tumours in male rats; and subcutaneous fibromas, thyroid gland follicular-cell tumours and Zymbal gland carcinomas in male and female rats. Subcutaneous administration to rats resulted in a high incidence of local sarcomas.

5.4 Other relevant data

CI Basic Red 9 lowers thyroxin levels and caused hypertrophy of the thyroid in rats and mice.

CI Basic Red 9 induced DNA damage in bacteria, but conflicting results were obtained in assays for gene mutation. Mitotic recombination was not induced in yeast. In cultured mammalian cells, there was no induction of sister chromatid exchange or chromosomal aberrations, but DNA damage and cell transformation were induced; assays for gene mutation gave inconsistent results.

5.5 Evaluations

There is inadequate evidence in humans for the carcinogenicity of magenta.

There is inadequate evidence in humans for the carcinogenicity of CI Basic Red 9.

There is sufficient evidence that the manufacture of magenta entails exposures that are carcinogenic.

There is sufficient evidence in experimental animals for the carcinogenicity of CI Basic Red 9.

There is inadequate evidence in experimental animals for the carcinogenicity of magenta.

Overall evaluation

The manufacture of magenta entails exposures that are carcinogenic (Group 1).

CI Basic Red 9 is possibly carcinogenic to humans (Group 2B).

Magenta containing CI Basic Red 9 is possibly carcinogenic to humans (Group 2B).

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluation: Magenta: Suppl. 7 (1987) (p. 238)

Synonyms for 4-[(4-Aminophenyl)(4-imino-2,5-cyclohexadien-1-ylidene)methyl]-2-
methylbenzenamine, monohydrochloride

Synonyms for 4-[(4-Aminophenyl)(4-imino-3-methyl-2,5-cyclohexadien-1-
ylidene)methyl]-2-methylbenzenamine, monohydrochloride

Synonyms for 4-[(4-Amino-3-methylphenyl)(4-imino-3-methyl-2,5-cyclohexadien-
1-ylidene)methyl]-2-methylbenzenamine, monohydrochloride

Synonyms for 4-[(4-Aminophenyl)(4-imino-2,5-cyclohexadien-1-ylidene)methyl]-
benzenamine, monohydrochloride


Last updated 08/22/1997






















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       Toxicological Abbreviations