Contact sensitivity to preservatives in Turkey.

This study was designed to evaluate the frequency of contact sensitivity to 14 common preservatives among patients with contact dermatitis in Turkey. From 2000 to 2004, 308 patients with the diagnosis of contact dermatitis were patch tested in the Department of Dermatology, Ankara University School of Medicine. All patients were patch tested with European standard series. In addition to the four preservatives included in the standard series, patients were also tested with DMDM hydantoin, imidazolidinyl urea, bromonitropropane diol, diazolidinyl urea, thimerosal, propylene glycol, chlorocresol, chloroxylenol, methyldibromoglutaronitrile/phenoxyethanol (MDBGN/PE) and benzalkonium chloride. Out of the 308 patients suspected of having contact dermatitis, 23 patients were found to have positive reactions to one or more preservatives. Preservatives that were the most frequent cause of positive reactions were thimerosal (1.6%), benzalkonium chloride (1.6%), formaldehyde (1.3%) and MDBGN/PE (0.9%). In our study, 65% of the positive reactions were caused by allergens not present in the standard series, such as thimerosal, benzalkonium chloride and MDBGN/PE. Although thimerosal caused a high rate of contact sensitivity, it may not be considered as an important allergen, because clinical relevance could not be found in any of the patients.