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EC number: 219-708-8
CAS number: 2503-73-3
The test substance, Direct Blue 78,was tested for the assessment of skin sensitisation potential with the murine local lymph node assay.
The Local Lymph Node Assay (LLNA) with the incorporation of 3H-methyl thymidine radionuclide was used. The testing was conducted according to the Method B.42 – Skin Sensitisation: Local Lymph Node Assay, Council Regulation (EC) No.640/2012, published in O.J. L 193, 2012.
Only one study is available.
Klimish score 1.
Table No. 8. Individual Activities and Calculated Values
Table No. 10. Summary Table
The test substance, Direct Blue 78,was tested for the assessment of skin sensitisation potential with the murine local lymph node assay. This study is a part of the test substance health hazard evaluation.
The Local Lymph Node Assay (LLNA) with the incorporation of 3H-methyl thymidine radionuclide was used. The testing was conducted according to theMethod B.42 – Skin Sensitisation: Local Lymph Node Assay, Council Regulation (EC) No.640/2012, published in O.J. L 193, 2012.
In this study the contact allergenic potential of Direct Blue 78 was evaluated after topical application to female BALB/c mice. Mice were exposed to three concentrations of test substance suspended in vehicle DAE 433 (mixture of 40% dimethylacetamide, 30% acetone and 30% ethanol) for 3 consecutive days.
In pilot experiment the following concentrationsof test substance in application forms were used: 50 %, 5.0 %, 0.5 % (w/v).According to the results of pilot experiment the same doses were confirmed for main study.
Primary proliferation of lymphocytes in the lymph node draining the site of application was evaluated using radioactive labelling of proliferating cells. The ratio of the proliferation in treated groups to that in vehicular controls, termed the Stimulation Index, was determined. The evaluation of ear weight was performed for elimination of false positive findings with certain skin irritants.
The animals exposed to the test substance at all doses showed no pathological and no other negative clinical symptoms of intoxication throughout the experiment.
The positive control item Dinitrochlorobenzene (DNCB) as a contact allergen (concentration 0.5% (w/v) elicited the expected reaction pattern with significant increase in Stimulation Index of cell proliferation and of ear weight. Appropriate performance of the assay in the test laboratory was then demonstrated.
Comparison of Stimulation Indexes between treated groups and control vehicle group revealed that the test substance Direct Blue 78 caused a significant and dose dependent increase in radioisotope incorporation into the DNA of dividing lymphocytes of animals treated by the test substance at the highest and the middle dose level. But the Stimulation Index in all treated groups was< 3.
The value SI is determined from the test (SI˂3). The value EC3 is calculated (the least squares method) and it is higher than 100%. Due to the substance Direct Blue 78 is not classified according to Regulation No. 1272/2008 CLP.
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