Heptasodium bis[4-hydroxy-5-[(2-hydroxy-1-naphthyl)azo]-3-[(2-hydroxy-3-nitro-5-sulphophenyl)azo]naphthalene-2,7-disulphonato(5-)]cobaltate(7-)

Endpoint summary

Description of key information

not a skin sensitiser

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The following data were obtained for Similar Substance 01 supported by data for Similar Substance 02. It is expected that the test item will present a similar skin sensitising profile. A detailed read-across justification is provided in Section 13 of IUCLID.

 

Similar Substance 01 was tested in Local Lymph Node Assay in mice (OECD guideline 429). Concentrations of 1 %, 2 % and 5 % w/w in DMF were used. In a pre-experiment, the 5 % concentration was found to be the highest concentration at which inexcessive local irritation and no systemic toxicity was noted.

In the main test, no signs of systemic toxicity were noted; erythema could not be evaluated due to the colour of the substance. No statistically significant increase in ear weight (cutoff value of 1.1 in BALB/c mice) was seen.

Stimulation Indices (S.I.) of 1.27, 2.01 and 2.22 were determined at concentrations of 1, 2, and 5% (w/w) in DMF, respectively. A clear dose-response relationship was observed, but the threshold value of 3 for positive response was not reached.

A statistically significant but biologically not relevant increase in lymph node cell count was observed in the mid and highest dose group in comparison to the vehicle control group. However, the cut-off value of 1.55 for a positive response in BALB/c mice was not reached in any dose group.

Overall, the substance resulted as not skin sensitiser in the LLNA assay.

A maximisation test was conducted on Similar Substance 02, using 10 female guinea pigs in the control group and 20 female guinea pigs in the test group. In a pre-test, concentrations for induction phase and challenge application in the main test were chosen.

The intradermal injections was performed at 1 % (w/v) test item in water and in the FCA/physiological saline mixture. After 8 days, an epidermal induction was performed using 25 % test item in vaselinum album. Challenges were carried out on days 22 and 29 using 25 % test item in vaselinum album by epidermal occlusive patch system.

Under the experimental conditions, none of the animals of the test or control group showed skin reactions 24 and 48 hours after removing the dressings. Therefore, the substance resulted to be non skin sensitiser. No positive reactions were reported in the available guinea pig maximisation test carried out on Similar Substance 02.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to the CLP Regulation (EC) 1272/2008, a skin sensitiser is a substance that will lead to an allergic response following skin contact.

In the case of a local lymph node assay (LLNA), a stimulation index ≥ 3 is considered positive. Under the test conditions, the simlulation index was below 3 at all test concentrations (1 %, 2% and 5 %).

In the case of a guinea pig maximisation test (GPMT), a response of at least 30 % of animals is considered positive. Under the experimental conditions employed, 0 % of animals in the test and control groups showed skin reactions 24 and 48 hours after removing the dressings.

Based on these findings, the Acid Black 076 is not classified as skin sensitiser, according to the CLP Regulation (EC) No 1272/2008.