Reaction mass of 5,5'-[sulphonylbis(3,1-phenyleneazo)]bis[6-amino-4-hydroxynaphthalene-2-sulphonic acid] and disodium 5,5'-[sulphonylbis(3,1-phenyleneazo)]bis[6-amino-4-hydroxynaphthalene-2-sulphonate]

Endpoint summary

Description of key information

not skin sensitizing

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The skin sensitization potential of the Target Substance was investigated using a specific QSAR model, developed to predict the skin sensitization potential for dyes. The existing QSAR models have strong limitations to predict ionic complex structures as the organic dyes are, and consequently they provide unreliable results. The QSAR modelling used was developed in accordance with the OECD principles (SKIN SENSITIZATION QSAR MODEL REPORT N. 08).

Based on the estimation, the substance is expected to be not sensitizing. The estimation resulted to be in the applicability domain of the model.

In order to confirm the results obtained by the QSAR prediction, the investigation performed on the analogue substance Similar Substance 01 is used as support of the prediction. Justification for Read Across is given in Section 13 of IUCLID.

The potential of the Similar Substance 01 to cause skin sensitisation reactions following topical application to the skin of CBA/JN mice, was assessed using the LLNA: BrdU-ELISA method, according to the OECD Guideline for testing of chemicals No. 442b. During the preliminary test five concentrations [25 (maximum feasible concentration), 10, 5, 2.5 and 1% w/w in acetone:olive oil 4:1 (v/v)] were tested in the preliminary phase, in order to identify a non toxic and minimally irritant concentration and avoid false positive results. No clinical signs were observed at the tested concentrations. Several animals showed a body weight loss, but not dose correlated. According to the results of the irritation screening, the concentration of 25% w/w was judged to be not irritant. During the Main assay the test item was topically administered at the concentrations of 25, 10 and 5% (w/w), in acetone: olive oil 4:1 (v/v). No mortality nor clinical signs were recorded in any animal. Changes in bodyweight observed during the study were within the expected range for this strain and age of animals. No increase in cell proliferation of draining lymph nodes was observed in any treatment group. The calculated Stimulation Indices (SI) were 1.13, 1.00 and 1.27, respectively at the low, mid- and high dose levels [5, 10 and 25 %, respectively]. No correlation with the doses nor statistical significance was observed. These results indicate that the test item does not elicit any sensitisation response in mice following dermal exposure.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

SKIN SENSITISATION

In the CLP Regulation (EC 1272/2008) a skin sensitizer is defined as “a substance that will lead to an allergic response following skin contact”. A substance classified as skin sensitiser (Category 1) may be allocated to one of the two sub-categories 1A or 1B in accordance with the criteria given in Annex I, Part 3, Table 3.4.2. However, in vitro/in chemico alternatives that have been validated and/or accepted may also be used to make classification decisions.

Based on the results of skin sensitisation, no classification for skin sensitization is warranted under the CLP Regulation (EC 1272/2008).