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Description of key information

Based on the result of the key study, and according to the CLP and GHS regulations, the test article 4 -amino-3 -nitrophenol was classified as Extreme sensitizer Category 1A.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

A GLP-compliant study (Sire, 2005) was performed to evaluate the potential sensitization of the test item according to OECD Guideline 429 method (adopted the 24th April 2004) for Local Lymph Node Assay and was considered as Key Study and Klimisch 1.

This assessment was made through two independent experiments using 28 animals each: 5 treated groups received the test item at the chosen concentration, one negative control group received the vehicle, one positive control received the reference item at the concentration of 25% (v/v). In the first exp. The test item was tested at 1, 2.5, 5, 10 and 25%. As positive results were obtained, the test item was tested in a second exp. at the concentrations of 0.05, 0.1, 0.5, 1 and 2.5%. In each experiment, the substances were applied for 3 consecutive days. After 2 days of resting, the proliferation of lymphocytes in the lymph node draining the application site was measured by incorporation of tritiated methyl thymidine. The irritant potential of the test item was assessed in parallel by measurement of ear thickness on days 1, 2, 3 and 6. n the 1st exp., positive lymphoproliferative responses were noted at all tested concentrations. The SI values increased in a dose-dependent manner in the treated groups given the test item concentrations comprised between 1 and 10% and decreased thereafter at the highest concentration. In the absence of local irritation, these positive lymphoproliferative responses were attributed to delayed contact hypersensitivity. In the second exp. (0.05-2.5%), a dose-related increase in the SI was noted and the threshold positive value of 3 exceeded at the conc. >=0.5%.

The EC3 value for the test item calculated on the basis of the results obtained in the second exp. is 0.2%. Under the experimental conditions, the test item induces delayed contact hypersensitivity in the murine Local Lymph Node Assay. According to the EC3 value obtained, the test item should be considered as a strong sensitizer.

Justification for classification or non-classification

Based on the result of the key study, The EC3 value was calculated at 0.2% for the test article 4 -amino-3 -nitrophenol in a LLNA. Hence, it was classified as Extreme sensitizer Category 1A according to CLP criteria.