Patch Test Positivity to Palladium: A 5-Year Retrospective Study in Triveneto Region, Italy

Background: The use of palladium (Pd) is increasing in metal objects after the banning of nickel in items in prolonged contact with the skin. The properties of Pd make this metal useful in various industrial fields. Objective: The aim of the study was to evaluate the prevalence of Pd sensitization in patients who underwent patch tests for suspected allergic contact dermatitis in the Triveneto region from 2013 to 2018. Methods: A total of 4816 patients with symptoms and/or signs of suspected contact allergic dermatitis were patch tested. Individual characteristics were assessed using a standardized questionnaire. Results: The overall prevalence of Pd sensitization was 7.6% and 10.8% using PdCl2 1% or 2% petrolatum, respectively, with a higher prevalence in women (odds ratio, 2.6; 95% confidence interval, 1.9-3.7) and in 26- to 55-year-old patients. Monosensitization occurred in 1%-1.5% of the patients tested. Health care workers and technicians were more sensitized to Pd than clerks, but the data did not reach statistical significance. Conclusions: Palladium sensitization was high, but it was mainly associated with nickel sensitization. A possible occupational role was found for workers with potential contact with Pd-containing objects, but more data are needed to reach statistical significance.