Trisodium bis[(3'-nitro-5'-sulfonato-(6-amino-2-[4-(2-hydroxy-1-naphtylazo)phenylsulfonylamino]pyrimidin-5-azo)benzene-2',4-diolato)]chromate(III)

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

not mutagenic

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

For the assessment of genetic toxicity, three different studies were available.

BACTERIA GENE MUTATION ASSAY

The test substance was tested for detecting its potential gene mutagenic activity using theSalmonella typhimuriumstrains TA 98, TA 100, TA 1535 and TA 1537. It should be noted that the study was performed only on 4 different strains of microorganisms instead of 5. This difference is due to the fact that the study was performed according to OECD 471 (1983) which was modified later in 1997.The tests were performed with and without metabolic activation. The test item was examined in two independent assays at 6 concentrations from 3.33 to 5000 µg/plate.

In the experiments performed, no relevant increase of the revertant colony numbers was observed in any Salmonella typhimurium strain tested, in the presence and in the absence of S9 mix. The test substance did not induced point mutations by base pair changes and frameshifts in the genome of the strains of Salmonella typhimurium used.

 

CHROMOSOMAL ABERRATION ASSAY

The test item was assessed for its potential to induce structural chromosome aberrations in V79 cells of the Chinese hamster in vitro in the absence and presence of metabolic activation by S9 mix. Two independent experiments were performed, according to the OECD Guideline 473 (1983). The chromosomes were prepared 18 h and 28 h after start of treatment with the test substance, which was dissolved in DMSO. The treatment interval was 4 h with metabolic activation, 18 h and 28 h without metabolic activation. The dose levels were in the range of 0.5-50 µg/L (18 h) and 5.0-50 µg/L (28 h).

In both experiments, at both fixation intervals in the absence as well as in the presence of S9 mix the test substance did not increase the frequency of cells with aberrations to a statistically or biologically relevant extent. In both experiments, no biologically relevant increase in the rate of polyploid metaphases as compared to the rates of the controls were found after treatment with the test substance. In both experiments EMS and CPA were used as positive controls and showed distinct increases in cells with structural chromosomal aberrations.

In conclusion, it can be stated that in the study described and under the experimental conditions reported, the test substance did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line.

MAMMALIAN CELL GENE MUTATION ASSAY

The test item was examined for mutagenic activity by assaying for the induction of 5 trifluorothymidine resistant mutants in mouse lymphoma L5178Y cells after in vitro treatment, in the absence and presence of S9 metabolic activation, using a fluctuation method.

A cytotoxicity assay was performed, both in the absence and presence of S9, at in dose levels from 0 to 2000 µg/mL..

Severe toxicity was observed at the highest dose level. Slight toxicity was noted at the next lower concentration and no relevant toxicity was observed over the remaining dose levels tested.

Three independent assays for mutation at the TK locus were performed.

In Main Assay I the test item was assayed after 3-hour treatment at 8 dose levels up to 1900 µg/mL. In the absence of S9 metabolism, severe toxicity was observed starting from 778 µg/mL; thus the number of analysable concentrations was not adequate for the evaluation of test item mutagenicity. In the presence of S9 metabolism, test item treatment yielded a steep decline in relative total growth (RTG) and no concentration tested showed an adequate level of cytotoxicity (RTG value between 10-20%).

The Main Assay II was performed using the a 3-hour treatment time at concentration ranges up to 751 µg/mL (absence S9) and up to 1200 µg/mL (presence S9). Adequate levels of cytotoxicity were obtained both in the absence and presence of S9 metabolic activation.

The Main Assay III was performed using a 24-hour treatment time at the concentrations up to 750 µg/mL. Mild toxicity was observed at the three highest dose levels, slight reduction in RTG was noted at the next two lower concentrations of 560 and 520 µg/mL, while no relevant toxicity was observed over the remaining concentrations tested.

In the all assays no relevant increases in mutant frequencies were observed following treatment with the test item, in the absence or presence of S9 metabolism.

Negative and positive control treatments were included in each mutation experiment in the absence or presence of S9 metabolism. The mutant frequencies in the solvent control cultures fell within the normal range. Marked increases were obtained with the positive control treatments, indicating the correct functioning of the assay system.

It is concluded that the substance did not induce mutation at the TK locus of L5178Y mouse lymphoma cells in vitro in the absence or presence of S9 metabolic activation, 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.

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

In conclusion, the substance does not meet the criteria to be classified for genetic toxicity according to the CLP Regulation (EC 1272/2008).