Chromate(3-), [3-[(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-2-hydroxy-5-nitrobenzenesulfonato(3-)][3-hydroxy-4-[(2-hydroxy-1-naphthalenyl)azo]-7-nitro-1-naphthalenesulfonato(3-)]-, sodium

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

Two Ames tests are available on Acid Brown 355 (Huntsman, 1985). They were performed on strain: TA 1535, TA 1537, TA 98, and TA 100.

Moreover, an ames test on similar substance 1 was performed (R&C, 2020) on strain TA98, TA100, TA102, TA1535, TA1537 and the nitroreductase deficient strains, TA 98NR and TA 100 NR.

The Huntsman tests were disrgegarded and the R&C test is considered in a Weight of Evidence approach for the reason discussed in the expert statement.

Therefore, one expert assessments was added as Key study, in order to analyse all the results of the Ames tests, considering also the structural and mechanicistic evaluations.

The final conclusion is that Acid Brown 355 has no concern fo mutagenicity in bacteria.

In the in vivo micronucleus test (OECD 474) ABr355b compound was administered orally to mice at a concentration of 1500 mg/kg of a solution at the maximal concentration of 75 mg/ml. No mutagenic effect was observed in bone marrow smears taken 20, 44 and 68 hours after administration of the test substance. A positive control (Thio-TEPA) administered at a concentration of 20 mg/kg showed pronounced evidence of mutagenicity 44 hours after administration. Thio-TEPA shows that the strain of mouse used is sensitive to mutagens and that such products can be detected using the micronucleus test (Huntsman Textile Effects (Germany) GmbH, 1986).

ABr355b (EC 280-689-4), trisodium salt: chromate(3-),[3-[(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-2-hydroxy-5-nitrobenzenesulfonato(3-)][3-hydroxy-4-[(2-hydroxy-1-naphthalenyl)azo]-7-nitro-1-naphthalenesulfonato(3-)]-, trisodium.

The reference substance under registration is the Acid Brown 355 (ABr355 - EC 284-915-2), the form which can have a variable number of the sodium atoms. Thus, although it has been appointed a different EC number to the ABr355b trisodium salt form (EC 280-689-4), it can be considered as “included” into the structure variability of the ABr355 (EC 284-915-2). In this context, the use of the experimental data available on the ABr355b (EC 280-689-4), in order to assess the ABr355 (EC 284-915-2), can be considered as not a read across, but an evaluation on one of the possible forms of ABr355.

Furthermore, based on the experience in the manufacture of ABr355, the most frequent form is the trisodium salt.

 

In order to assess also the mammalian cell gene mutation potential, data available on the structural analogue 03 have been taken into account. A study was performed to investigate the potential of test substance to induce gene mutations at the HPRT locus in V79 cells of the Chinese hamster. The assay was conducted in three independent experiments, both with and without liver microsomal activation. According to the pre-test on toxicity the concentration ranges were selected to yield concentration-related toxic effects. The highest concentration produced a low level of survival and the survival at the lowest concentration was approximately in the range of the negative control. Up to the highest investigated concentration no relevant increase in mutant colony numbers was obtained in all independent experiments. Appropriate reference mutagens were used as positive controls and showed a distinct increase in induced mutant colonies. Under the experimental conditions reported the test article did not induce gene mutations at the HPRT locus in V79 cells (Huntsman Textile Effects (Germany) GmbH, 1995).

 

The read across approach has been further detailed in the report attached to the IUCLID section 13.

 

Justification for selection of genetic toxicity endpoint

The assessment of the endpoint is performed with the integrated evaluation of results for in vitro bacteria gene mutation, in vitro mammalian cell gene mutation assay and in vivo micronucleus assay

 

Short description of key information:

Non mutagen

 

Endpoint Conclusion: No adverse effect observed (negative)

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 substance is not classified for genetic toxicity according to the CLP Regulation (EC 1272/2008).