Reaction mass of 5,5'-[sulphonylbis(3,1-phenyleneazo)]bis[6-amino-4-hydroxynaphthalene-2-sulphonic acid] and disodium 5,5'-[sulphonylbis(3,1-phenyleneazo)]bis[6-amino-4-hydroxynaphthalene-2-sulphonate]

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

No mutagenic

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The AMES Mutagenicity potential of the substance was investigated using a specific QSAR model, developed to predict the skin AMES Mutagenicity potential for dyes. The existing QSAR models have strong limitations to predict ionic complex structures as the organic dyes are, and consequently they provide unreliable results. The QSAR modelling used was developed in accordance with the OECD principles (AMES MUTAGENICITY QSAR MODEL REPORT N. 07).

Based on the estimation, the substance is expected to be negative in the AMES Mutagenicity assay. The estimation resulted to be in the applicability domain of the model.

 

In order to confirm the results obtained by the QSAR prediction, the investigation performed on the analogue substance Similar Substance 01 is used as support of the prediction. Justification for Read Across is given in Section 13 of IUCLID.

 

The Similar Substance 01 was examined for the ability to induce gene mutations in tester strains of Salmonella typhimurium and Escherichia coli, as measured by reversion of auxotrophic strains to prototrophy, according to the OECD471, in GLP. The five tester strains TA1535, TA1537, TA98, TA100 and WP2 uvrA were used. Experiments were performed both in the absence and presence of metabolic activation, using liver S9 fraction from rats pre-treated with Phenobarbital and 5,6-Benzoflavone (Standard metabolic activation) in Main Assay I, and liver S9 fraction from uninduced hamsters (reductive metabolic activation system with Prival modification), in Main Assay II. The test item was used as a solution in sterile water for injection and, as requested by the Sponsor, concentrations were expressed in terms of active ingredient.

Toxicity test: the test item was assayed in the toxicity test at a maximum concentration of 5000 µg/plate and at four lower concentrations spaced at approximately half-log intervals: 1580, 500, 158 and 50.0 µg/plate.

Main Assay I: on the basis of toxicity test results, inMain Assay I, using the plate incorporation method, the test item was assayed at the following dose levels: 5000, 2500, 1250, 625 and 313 µg/plate.

Main Assay II: as no relevant increase in revertant numbers was observed at any concentration tested, Main Assay II was performed. Based on the chemical structure of the test item (azo-dyes), the experiment was performed using the pre-incubation method in the presence of a reductive metabolic system (hamster S9 supplemented with flavin mononucleotide cofactory). The test item was assayed at the following dose levels: 5000, 2500, 1250, 625 and 313 µg/plate.

The following results were observed:

Toxicity test: at the end of the incubation period, no precipitation of the test item was observed with any tester strain, at any concentration tested, in the absence or presence of S9 metabolism.

No toxicity neither increases in revertant colonies were observed with any tester strain, at any dose level, in the absence or presence of S9 metabolism.

Main test I: no precipitation of the test item was observed, at the end of the incubation period, with any tester strain, at any concentration tested, in the absence or presence of S9 metabolism.

No toxicity neither increases in revertant colonies were observed with any tester strain, at any concentration tested, in the absence or presence of S9 metabolism.

Main test II: no precipitation of the test item was observed, at the end of the incubation period, with any tester strain, at any concentration tested, in the absence or presence of S9 metabolism.

No toxicity neither mutagenicity was noticed with any tester strain, at any dose level, in the absence or presence of S9 Prival metabolizing system.

The test item did not induce two-fold increases in the number of revertant colonies in the plate incorporation or pre-incubation assay, at any dose level, in any tester strain, in the absence or presence of S9 metabolism.

It was concluded that the test item does not induce reverse mutation in Salmonella typhimurium or Escherichia coli in the absence or presence of S9 metabolism, under the reported experimental conditions.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), for the purpose of the classification for germ cell mutagenicity, substances are allocated in one of two categories in consideration of the fact that they are:

- 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 or

- substances which cause concern for humans owing to the possibility that they may induce heritable mutations in the germ cells of humans.

 

Based on the results of mutagenicity (AMES), no classification for mutagenetic toxicity is warranted under the CLP Regulation (EC 1272/2008).