3-[[4-[(2-chloro-4-nitrophenyl)azo]phenyl]ethylamino]propiononitrile

Endpoint summary

Description of key information

Skin sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Skin sensitising potential of Disperse Red 050 was assessed using a read across approach, as available data on target substance was scarce and of unclear interpretation. Similar Substance 01 was used as read across substance and further details are reported in section 13.

Disperse Red 050 was tested in mixture with 3 other dyes in a repeated insult patch test to evaluate dermal effects in humans. Occlusive application was continued for 4 weeks from Monday to Friday; on the second Monday, following last week of application, challenge was done with a contact period of 48 h duraton. After removal, sites were examined, then re-examnined after 24 and 48 h. At challenge 2 out of 200 individuals showed positive responses. Upon testing with separate components of the mixture, Disperse Red 050 induced a positive reaction in one of the 2 sensitised individual.

Based on such result, Disperse Red 050 was associated to a potential hazard upon prolonged skin contact. However, as no data on Disperse Red 050 as such was available, but only data upon application of a mixture of 4 dyes, possible interefering effects could not be excluded. Accordingly, these findings were only used as supporting evidence to findings in the key study.

An available study on Similar Substance 01 was used as key study. Similar Substance 01 was tested in the Buheler test, according to OECD guideline 406.

Twenty female animals of test group were treated topically with test substance at 50 % in bi-distilled water once a week for a 3-week induction phase. Two weeks after the final induction application, animals were challenged with test substance at 50 % concentration in bi-distilled water. Ten animals of the control group were not treated during the induction but were treated once at challenge with test substance at 50 % in bi-distilled water.

After challenge, 40 % of animals of test group showed skin reactions, while no skin reactions were observed in the control group. Therefore, test substance was considered as skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Category 1

Substances shall be classified as skin sensitizers in category 1 where data are not sufficient for sub-categorisation in accordance with the following criteria:

(a) if there is evidence in humans that the substance can lead to sensitisation by skin contact in a substantial number of persons; or

(b) if there are positive results from an appropriate animal test.

As for Buehler test, a response of at least 15 % of animals is considered positive.

Subcategorisation is done as follows in case of a Buehler assay:

Sub-category 1A

Substances showing a high frequency of occurrence in humans and/or a high potency in animals can be presumed to have the potential to produce significant sensitisation in humans. Severity of reaction may also be considered.

Specific criteria: ≥ 15 % responding at ≤ 0.2 % topical induction dose or ≥ 60 % responding at > 0.2 % to ≤ 20 % topical induction dose

Sub-category 1B

Substances showing a low to moderate frequency of occurrence in humans and/or a low to moderate potency in animals can be presumed to have the potential to produce sensitisation in humans. Severity of reaction may also be considered.

Specific criteria: ≥ 15 % to < 60 % responding at > 0.2 % to ≤ 20 % topical induction dose or ≥ 15 % responding at > 20 % topical induction dose.

Based on data derived from a Buehler assay, i.e. 40 % of test animals responding at 50 % topical induction dose, the substance is threfore classified in category 1B of the CLP Regulation (EC 1272/2008)