Tetrasodium 7-[[4-[[4,6-bis[(3-sulfonatopropyl)thio]-1,3,5-triazin-2-yl]amino]-3-methoxyphenyl]azo]naphthalene-1,3-disulfonate

Endpoint summary

Additional information

In vitro data

Bacterial reverse mutation

Two studies are available both investigating the potential of the test material to cause gene mutation in bacterial strains in accordance with standardised guidelines OECD 471 and EU Method B.13/14. In the key study, four trains of Salmonella typhimurium (TA1535, TA1537, TA98 and TA100) and one strain of Escherichia coli (WP2 uvr A) were treated in the presence and absence of a metabolic activation system (S9 mix). In two separate assays, the test material did not induce any significant, reproducible increases in the observed number of revertant colonies in any of the tester strains used in the absence or absence of metabolic activation.

In the supporting study, five trains of Salmonella typhimurium (TA1535, TA102, TA100, TA98 and TA97a) were treated in the presence and absence of a metabolic activation system (S9 mix). In two separate assays, the test material did not induce any significant, reproducible increases in the observed number of revertant colonies in any of the tester strains used in the absence or absence of metabolic activation. Cytotoxicity of the test material was not detected. The background lawn was visible and the number of revertants was not significantly decreased.

Chromosome aberration test in vitro

The potential of the test material to induce structural chromosomal aberrations was determined in a study performed in accordance with standardised guidelines OECD 473 and EU Method B.10. Under the conditions of the study no significant increase in the frequency of cells with structural chromosomal aberrations was noted in either experiment at any of the harvest times. Therefore it can be concluded that, under the conditions of the study, the test material did not induce chromosomal aberrations in cultured human lymphocytes.

In vitro gene mutation in mammalian cells

The mutagenic potential of the test material was investigated in a study which was conducted under GLP conditions and in accordance with the standardised guidelines OECD 476 and EU Method B.17. Under the conditions of the study, the test material showed weak mutagenic activity in cultured mammalian cells. However, the effect was small, and it was only observed at high concentrations of the test material that caused marked toxicity.

Given the pattern of the results, oxidative stress is considered the most likely origin of the small increase in mutation frequency in the mouse lymphoma assay (suspected by some as being abnormally sensitive to this mechanism). The oxidative stress was ultimately cytotoxic (once reductive capacity of the cells had been overwhelmed), and mutagenicity was secondary to this process, with at least 50 % cytotoxicity required before the manifestation of increased mutation frequencies (i.e. the effect has a threshold). The presence of S9 ameliorated the response by providing extra reductive capacity to the cell. Increased time of exposure reduced the concentration of test material required to deplete or overwhelm the cells’ reductive capabilities.

Please refer to section 13 of the dataset for an assessment on the relevance of the results of this study.

Justification for selection of genetic toxicity endpoint
As multiple studies are presented to address genetic toxicity, no one study was selected as the key study as they represent different types of genetic toxicity and are therefore not comparable.

Short description of key information:
IN VITRO DATA
Reverse mutation in bacteria: Negative (S. typhimurium strains TA 1537, TA 1535, TA 100, TA 98 and E. Coli WP2 uvr A, +/- S9-mix), OECD 471, EU method B.13/14, Haddouk 1998

Reverse mutation in bacteria: Negative (S. typhimurium strains TA 1535, TA 102, TA 100, TA 98 and TA 97a (+/- S9-mix), OECD 471, EU Method B.13/14, Rudolf 2008

In vitro chromosome aberration: Negative, human lymphocytes with and without metabolic activation, OECD 473, EU Method B.10, Haddouk 2002

In vitro gene mutation in mammalian cells: Weak mutagen at high concentrations that caused marked toxicity, postulated to be caused by oxidative stress, OECD 476, EU Method B.17, Hargitai 2014

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

In accordance with criteria for classification as defined in Annex I, Regulation (EC) No 1272/2008, the test material does not require classification for genetic toxicity based on the overall negative response noted in the available genetic toxicity studies.