Hexasodium 2,2'-[vinylenebis[(3-sulphonato-4,1-phenylene)imino[6-[bis(2-hydroxyethyl)amino]-1,3,5-triazine-4,2-diyl]imino]]bis(benzene-1,4-disulphonate)

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

No specific tests on the substance under registration was performed, nevertheless the substance belongs to the Stilbene Fluorescent Whitening Agents category, group 3, in which all members share the common organic functional group dihydroxyethylamino derivative, with different sulphonation degrees: acid form (OB 3a-A(free acid), disulphonated sodium salt (OB 3a-A(Na), disulphonated sodium/potassium form (OB 3a-A(NaK) tetrasulphonated (OB 3a-MSA)and hexasulphonated (OB 3a-DSA).

 

All substances of the category were modelled with the OECD Toolbox and the provisional results about mutagenicity alerts were calculated for all members and their metabolites. The same alert was reported based on the Hacceptor-path3-Hacceptor. This alert explores the possibility that a chemical interacts with DNA and/or proteins via non-covalent binding, such as DNA intercalation or groove-binding (Snyder et al. 2006). Among the descriptors potentially accounting for non-covalent interactions, the present molecular framework representing two bonded atoms connecting two H bond acceptors (calculated with software Leadscope Enteprise 2.4.15-6) resulted in an increased sensitivity/specificity for what concerns the Micronucleus training set. Experimental tests both in vivo and in vitro demonstrate that this alert is not expressed in none of the substances of the group. Based on all those considerations the available studies on the analogous substances are representative for the also that can then be considered not genotoxic.

 

Mutagenicity is a non-threshold endpoint, therefore mutagenicity potential is evaluated firstly based on the reactivity of the substance in itself, bound to chemical structure, functional groups and metabolism pathway, than on the bioavailability potential. Moreover the first screening in vitro is conservative regarding the end point, since the substance is put into the reaction plate even if potentially it will never been absorbed and will never express the mutagenic potential.

 

Mutagenicity in bacterial reverse mutation assays (Ames test) was investigated in two studies on the similar substance OB 3a-A(Na) (CCR Cytotest cell research GmbH, 1998 and Microtest Research Ltd., 1989) with negative results.

The substance under registration was assayed for the mutagenicity by the In Vitro Mammalian Cell Gene Mutation Test. V79 hamster fibroblast were used for testing and experiments were performed without as well as with of metabolic activation using the supernatant of rat liver and a mixture of cofactors. The experiment gives no evidence of the mutagenicity of test substance, thus the test substance resulted non-mutagenic for V79 cells without as well as with metabolic activation (Täublová, 2014).

The chromosome aberration potential was investigated for the analogous OB 3a-MSA, both in vivo ad in vitro and the results were used as supporting studies: no indication of a mutagenic effect were recorded in the in vitro test (CCR- Cytotest Cell Research GmbH & Co. KG, 1991) and in the in vivo dominant lethal assay (Bayer AG, 1995); furthermore the substance did not induce micronuclei as determined by the micronucleus test with bone marrow cells of the mouse (CCR - Cytotest Cell Research GmbH & Co KG, 1991).

CAS 16470-24-9 is a similar substance within the category of Stilbene Fluorescent Whitening Agents, the analogous dihydroxyethyl derivative tetrasulphonated sodium salt.

 

A further in vivo chromosomal aberration test, dominant lethal assay, was performed on the analogous OB 3a-A(Na) (Lorke D. and Machemer L., 1973). The compound was administered orally in single dose to NMRI mice by gavage at the concentration of 5000 mg/kg. Methylmethanesulfonate (MMS) and trimethyl phosphate (TMPO) were used as positive controls. Each of the 20 male mice in each group was mated with three untreated females directly after treatment. After insemination (determined by vaginal smear), or after a week, the females were isolated. This procedure was repeated weekly for eight weeks. On the fourteenth day of gestation the females were sacrificed and the numbers of fertile matings, implantations, resorptions, live foetuses, and corpora lutea were determined. The dominant lethal test investigation did not shown any evidence of mutagenicity caused by the test substance.

 

Read across within the same subgroup is well justified in these cases also taking into account the impurities of the considered substances, since the identified organic impurities can have different substitution on the molecule, but the functional reactive groups are potentially the same, and molecules are of the same molecular size and polarity of the main component. As a consequence the systemic absorption and reactivity is practically the same than the main constituent and Read Across is justified.

REFERENCES

Snyder, R. D., Ewing, D. and Hendry, L. B. 2006. DNA intercalative potential of marketed drugs testing positive in in vitro cytogenetics assays.

Justification for selection of genetic toxicity endpoint

Evaluation of the endpoint has been performed with the integrated evaluation of the following studies: in vitro Ames test (RCC - Cytotest Cell Research Gmbh, 1998), in vitro gene mutation on mammalian cells (Täublová, 2014), both in vitro and in vitro chromosomal aberration (CCR- Cytotest Cell Research GmbH & Co. KG, 1991, CCR- Cytotest Cell Research GmbH & Co. KG, 1991, Bayer AG., 1995 and Bayer AG., 1993).

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.

The test substance did not show any reasons of concern in the test performed.

In conclusion, the available experimental data are adequate for classification and labelling and the substance is not classified for genetic toxicity according to the CLP Regulation (EC 1272/2008).