Contact eczema and epicutaneous tests--distribution of allergens and changes in the spectrum in Vienna

Thousands of contact antigens have been defined. It is, however, remarkable that only a small group of substances (15 to 20) have proved to be frequent or otherwise important causes of allergic contact dermatitis. In agreement with reports from comparable centres, metals are high up on the "hitlist" of frequent allergens (nickel 24%, cobalt 9%, chromates 6%), followed by ingredients of cosmetics and toiletries (fragrances 16%, balsam of Peru 10%, Kathon 5%), whilst already way back are topical medicines (neomycin 4%, parabens 3%, lanolin 2%, benzocaine 1%) and rubber additives (thiuram-mix 2% and carba-mix 1%). Almost all other substances lie below the 1% limit. There was only one remarkable exception in comparison with the results of most other European studies, namely thiomersal, which is widely distributed as a preservative in vaccines in Austria and climbed to second place, with a sensitization rate of 18%. Although the phenylborate mercurials (historic sensitizations due to topical antiseptics) still reached a surprisingly high incidence of 6%, there were hardly any cases of cross-sensitization with thiomersal. A comparison with the international literature illustrates Austria-specific trends and a change in the spectrum over the past years. Interpretation of patch testing requires great specialist knowledge and experience.