**5. Conclusion**

Numerous studies have investigated the prevalence and risk factors of hand eczema in the general population. Contact sensitization has become a significant public health problem. In many parts of the world, more than 20% of the adult population is suffering from contact allergy. The profile of sensitizations may differ in each country. However, nickel sulphate is the most prevalent allergen practically everywhere. Patch testing remains the gold standard for the diagnosis of ACD. Quality control of patch testing is both a prerequisite for, and an objective of, clinical epidemiology of contact dermatitis. Publications based on data of patients visiting dermatology clinics and/or patch testing units cannot be used to directly derive population related incidence or prevalence estimates.
