Frequency of contact sensitization to European Standard Series (ESS) in contact and/or atopic dermatitis patients in Rasht, Ahwaz, Kerman and Hamedan

Background and aim: The frequency of sensitization to contact allergens varies in different countries because of both genetic and, more importantly, allergen exposure variations. The objective is to determine the frequency of sensitization to contact allergens in Iranian patients with dermatitis.Materials and methods: Four hundreds and one patients with a clinical diagnosis of contact dermatitis and/or atopic dermatitis were evaluated with a 24-allergen European standard series in four major cities in Iran. The patches were applied on the back of the patients, removed after 24 hours and the readings were taken on 24, 48 and 72 hours after application.Results: One hundred and seventy six patients (43.8%) showed at least 1 positive reaction with a total positive reactions of 268, and 64 patients (15.9%) had 2 or more positive reactions. The 5 most common allergens were nickel sulfate [64 (15.9%)], potassium dichromate [40 (10.0%)], thiuram mix [27 (6.7%)], cobalt chloride [23 (5.7%)], and Balsam of Peru [17 (4.2%)]. Contact allergy to nickel sulfate was significantly more common in female patients and in patients under 40 years of age (P<0.001).Conclusion: Nickel sulfate is the most common contact allergen in Iran, mostly affecting women and younger patients probably because of more exposure. Thiuram had a significant increase in its prevalence during the previous years and further studies need to distinguish its causes.