The present comparative study comprises the analysis of 6 representative new substances (textile dyes). The purpose of these studies was to derive information about the skin sensitizing potency of the selected textile dyes in the local lymph node assay (LLNA). All 6 textile dyes had previously been tested under the notified new substance regulation (German Chemicals Act) in Magnusson-Kligman maximization test in guinea pigs and had been characterized as skin sensitizing.

The additional testing in the LLNA was performed in order to assess the relative sensitization potency of the textile dyes. For this purpose, the 6 textile dyes were studied in parallel, using identical concentrations (as far as technically possible) and the same vehicle. Since this study involved repetition of animal testing notification according to § 8 section 7, article 1a of the German Animal Welfare Act was required.

According to the criteria of OECD guideline 429 (OECD Guidelines for Testing of Chemicals, number 429 "Skin Sensitization: Local Lymph Node Assay" (adopted: 24th April 2002)), 3 of the tested substances are considered skin sensitizing, whereas 3 are considered non-sensitizing. The EC₃ values could not be calculated by linear interpolation for any of the 6 substances, since all concentrations either yielded stimulation indices greater than 3 or less than 3. Therefore, an attempt was undertaken to estimate EC₃-values for the positive substances.

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