W. Wigger- Alberti (1), M. Keskin (1), G. Feistkorn (2), K.P. Wilhelm (1)

Assessment of patch test reactions due to hair dyes with the Laser doppler perfusion scanning technique

(1) proDERM Institute for Applied Dermatological Research GmbH, D 22869 Schenefeld, Germany
(2) Wella AG, D 64295 Darmstadt, Germany

Introduction:
The interpretation of test reactions of epicutaneous patch tests might be difficult in cases where coloured test products such as hair dyes have to be assessed. The subjective clinical scoring is influenced by the colour and even the benefit of colorimeters is limited. The aim of the present study was to investigate.the usefulness of the laser Doppler perfusion technique to investigate skin irritation alter application of hair dyes with different irritant potential.

Methods:
In order to basically test the practicability of this approach SLS was added to a hair dye at different concentrations (0.5%, 1%, 2%). Products were applied to the forearms of 15 volunteers. On day 1 and 3 visual sconng and instrumental measurements (chromametry, TEWL and Laser Doppler perfusion technique) were performed.

Results:
With visual scoring a significant difference was only detected an areas without dye, between 0.5% SLS and 2% SLS. With TEWL and LDI measurements significant differentes were detected between the dye without irritant and all test products with dye and 1% or 2% SLS. Chromametry, however, did not show differentes that could plausibly be correlated to the irritation potential of the test products.

Conclusion:
Dependent an the type of irritant TEWL and Laser Doppler perfusion imaging are recommended as the methods of choice when evaluating skin irritation potential of coloured test products.

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