2,7-Naphthalenedisulfonic acid, 4-amino-3,6-bis[2-[4-(ethenylsulfonyl)phenyl]diazenyl]-5-hydroxy-, sodium salt (1:2)

Endpoint summary

Additional information

Mutagenic behaviour of Reactive Black 5 in its bis-ester form was assessed in bacteria in vitro. In a GLP compliant study according to OECD 471 no mutagenic effects have been noted in the plate incorporation tests and in the preincubation tests conducted both in presence and absence of an exogenous metabolic activation system. In addition, also data on one of the metabolic breakdown products of Reactive Black 5 are available showing also no mutagenic effects in the bacterial test system.

To support these initial findings, mutagenic and clastogenic effects have been investigated in vivo. A GLP compliant study according to OECD 475 investigated effects of the test substance on chromosomal level after single treatment of 5000 mg/kg bw. The test item was administered once orally by gavage in a single dose of 5000 mg/kg bodyweight to male and female Chinese hamsters. This dose had been shown in a preliminary study to be the maximum tolerated dose. As a result no increase of chromosomal aberrations have been noted compared to control. Therefore the test was judged negative (non-clastogenic) in this in vivo test system.

To test mutagenic behaviour of the test item in vivo, the test substance was administered once by gavage as single doses of 0 (vehicle control), 2000 and 10000 mg/kg bodyweight to male and female NMRI mice (5 mice per sex and killing time point). 10000 mg/kg bw had been shown in a preliminary study to be the maximum feasible dose. A positive control group received Endoxan at an oral dose of 50 mg/kg body weight. Animals were killed 12, 24, or 48 hours after treatment. The bone marrow obtained from femora of the animals was prepared, placed on microscopic slides and stained. 1000 poly- and 1000 normochromatic erythrocytes were screened for micronuclei. In addition, the ratio of polychromatic to normochromatic erythrocytes was determined. Under the conditions tested, the test item caused no significant increase in the number of cells with micronuclei in the bone marrow cells of treated animals as compared with the control group. The results indicate that, under the conditions of the test, the test item is not mutagenic in the in vivo micronucleus test.

Based on these results in vivo, the test substance is considered to be not mutagenic and not clastogenic in vivo.

Short description of key information:
The test substance showed negative results in the Salmonella typhimurium reverse mutation assay (OECD 471) in vitro and in OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test) and in OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test) studies in vivo. The substance is therefore considered to be non-mutagenic and non clastogenic.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available genotoxicity studies, the test substance does not need to be classified for genotoxicity according to Directive 67/548/EEC and according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.