Trisodium bis[3-hydroxy-4-[(2-hydroxy-1-naphthyl)azo]-7-nitronaphthalene-1-sulphonato(3-)]chromate(3-)

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation in bacteria: positive in some strains

Gene mutation in mammalian cells: negative

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

Micronucleus test: negative

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

The test material was found to cause equivocal mutagenic effects in bacterial tests in specific strains (mainly TA 1537 and TA 98). However, the findings mostly did not show clear dose-response relations and were not confirmed in mammalian cells in vitro in two independent studies (HPRT).

The negative results of these tests are supported and confirmed in an in vivo micronucleus study in mice using intraperitoneal application, which also produced no indication of genetic damage. The significance of a positive result in a sister chromatid exchange could not be evaluated due to the lack of documentation and majoir methodological deficiencies.

Overall, the mutation test in mammalian cells (HPRT) is a model clearly closer to the human situation than the Ames Test in bacteria and is considered more representative than the bacterial test system. The negative results of this test are confirmed in two studies and additionally supported by the negative result of the micronucleus test in vivo in mice.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), a substance is classified for the genotoxic potential of:

CATEGORY 1:

substances known to induce heritable mutations or to be regarded as if they induce heritable mutations in the germ cells of humans. Substances known to induce heritable mutations in the germ cells of humans.

Category 1A:

the classification in Category 1A is based on positive evidence from human epidemiological studies. Substances to be regarded as if they induce heritable mutations in the germ cells of humans.

Category 1B:

the classification in Category 1B is based on:

- positive result(s) from in vivo heritable germ cell mutagenicity tests in mammals; or

- positive result(s) from in vivo somatic cell mutagenicity tests in mammals, in combination with some evidence that the substance has potential to cause mutations to germ cells. It is possible to derive this supporting evidence 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

- positive results from 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 The 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:

- somatic cell mutagenicity tests in vivo, in mammals; or

- other in vivo somatic cell genotoxicity tests which are supported by positive results from in vitro mutagenicity assays. Note: Substances which are positive in in vitro mammalian mutagenicity assays, and which also show chemical structure activity relationship to known germ cell mutagens, shall be considered for classification as Category 2 mutagens.

Based on the negative results of the relevant in vitro and in vivo studies the test material is not regarded as mutagenic and not classified.