Benzyl 4-[(1-butyl-5-cyano-1,6-dihydro-2-hydroxy-4-methyl-6-oxopyridin-3-yl)azo]benzoate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Not mutagenic

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Three reverse mutation bacterial mutagenesis assays (Ames tests) were performed on Disperse Yellow 231. All three assays were performed both in the presence and absence of metabolic activation using Salmonella typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538. In the test form 1982, an additional strain was tested (Escherichia coli WP2 uvrA).

The Ames tests from 1982 and 1980 did not demonstrate any evidence of increased frequency of revertant colonies at any concentration, with or without metabolic activation, in any strain. In the Ames test from 2000, test item showed weak evidence of mutagenic potential in S. typhimurium strains TA98 and TA1538 in the presence of metabolic activation.

An additional in vitro mutagenesis test was performed: a thymidine kinase (tk) mouse lymphoma assay was performed to evaluate the potential for the substance to elicit a mutagenic effect in the L5178Y mouse lymphoma cells. Test item resulted to be non mutagenic in this assay.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), the term mutation refers a permanent change in the amount or structure of the genetic material in a cell, both to heritable genetic changes that may be manifested at the phenotypic level and to the underlying DNA modifications when known (including specific base pair changes and chromosomal translocations). The terms mutagenic and mutagen are used for agents giving rise to an increased occurrence of mutations in populations of cells and/or organisms.

For the purpose of the classification for germ cell mutagenicity, substances may be allocated to one of two categories:

- Category 1: substances known to induce heritable mutations or to be regarded as if they induce heritable mutations in the germ cells of humans or substances known to induce heritable mutations in the germ cells of humans. Further sub-classification can be made into the following:

- Sub-category 1A: in the presence of positive evidence from human epidemiological studies; or

- Sub-category 1B: in the presence of positive result(s) from (i) in vivo heritable germ cell mutagenicity tests in mammals; (ii) in vivo somatic cell mutagenicity tests in mammals, in combination with some evidence that the substance has the potential to cause germ cells mutations (derived from mutagenicity/genotoxicity tests in germ cells in vivo, or by demonstrating the ability of the substance or its metabolite(s) to interact with the genetic material of germ cells); or (iii) tests showing mutagenic effects in the germ cells of humans, without demonstration of transmission to progeny; for example, an increase in the frequency of aneuploidy in sperm cells of exposed people.

- Category 2: substances which cause concern for humans owing to the possibility that they may induce heritable mutations in the germ cells of humans. Classification in Category 2 is based on positive evidence obtained from experiments in mammals and/or in some cases from in vitro experiments, obtained from either (i) somatic cell mutagenicity tests in vivo, in mammals; or (ii) other in vivo somatic cell genotoxicity tests which are supported by positive results from in vitro mutagenicity assays.

Based on available experimental results, i.e. no increse of gene mutation in mammalian cells and only a weakly positive result for bacterial cell mutagenic potential in one out of three Ames tests, Disperse Yellow 231 is considered not mutagenic. Therefore, no classification for genotoxicity is warranted according to the CLP Regulation (EC 1272/2008).