Sensitization to Nickel (Sulphate 5%) in North‐Eastern Italy, 1997–2023: Prevalence, Trend Over Time and an Evaluation of the Occupational Risk

Although decreasing over time, the prevalence of positive patch test reactions in this study is confirmed to be higher than that in Northern European countries. The latter pattern probably reflects delayed and less stringent application of the European directive. The U-trend of positive patch test reactions by birth year in female patients points to nickel exposure and sensitization in females aged 20-50 years before the enforcement of the European directive. Higher prevalence of positive patch test reactions in sellers could reflect prolonged exposure in coin handling occupations, whereas lower prevalence in retirees and housewives may be a result of reduced immune reactivity with increasing age.