D2.71 - Metal Skin Sensitization in High-Risk Occupations: A 31-Year Patch Test analysis from a Tunisian Occupational Medicine Unit

Occupational contact dermatitis caused by metals such as nickel, chromium, and cobalt remains a major source of work-related morbidity worldwide. Long-term epidemiological data from North Africa are limited. This study analyzes patch test results collected over a 31-year period in Tunisia to describe metal sensitization patterns, identify high-risk occupations, and determine occupational predictors.

We conducted a retrospective descriptive study of adult patients patch-tested over a 31-year period at the Dermato-Allergology Unit of the Occupational Medicine Department, CHU Farhat Hached, Sousse, Tunisia. Collected variables included age, sex, handedness, occupation, tested metals (nickel sulfate, potassium dichromate, cobalt chloride), exposure history, and etiological attribution. High-risk occupations were predefined as metal-related jobs (mechanics, welders, carpenters, jewelers, metalworkers). Positive reactions were defined as ≥1+ according to international criteria. Associations were assessed using chi-square tests, with p<0.05 considered significant.

Among 1,310 patients (mean age 45.2 ± 12.3 years; 62.5% men), approximately 80% were active workers. Metal sensitization was identified in 324 cases (24.7%), with nickel being the most frequent allergen (12.8%), followed by chromium (7.0%) and cobalt (4.9%). High-risk occupations represented 18.9% of patients and exhibited significantly higher sensitization rates than other professions (35.1% vs. 21.2%, p<0.001). Hands were the predominant site of involvement (58.3% of metal-positive cases). Occupational etiology was retained in 41.7% of metal-related dermatitis and was significantly associated with right-handedness (p=0.02). Only 9.5% of cases were officially recognized as occupational diseases.

Over three decades, metals emerged as leading occupational allergens in Tunisia, disproportionately affecting workers in metal-related professions. The predominance of hand involvement highlights the need for targeted preventive strategies, including exposure substitution, appropriate personal protective equipment, and early patch testing, to reduce the burden of occupational contact dermatitis.