Is nickel allergy an occupational disease? Discussion of the occupational relevance of a type IV allergy to nickel (II) sulfate using case reports.

Type IV sensitization to nickel (II) sulfate is common in the general population. Nickel can be found in different metals leading to occupational exposition in industrial professions. The individual clinical relevance of nickel allergy can easily be identified but it can be difficult to assess if nickel allergy was acquired privately or occupationally. The problem if nickel allergy fulfills the criteria of an occupational skin disease is presented in three case reports. The occupational relevance of a type IV sensitization to nickel in a chemical laboratory assistant, a flight attendant and a cashier are discussed. Important conditions for acquiring nickel allergy are contact with nickel-plated and nickel-releasing materials, the kind of skin contact, the status of the epidermal barrier, and the individual working conditions with an increased bioavailability of nickel. In cases of type IV sensitization to nickel, the affected person cannot continue to work in metal plating or with contact to nickel-plated metals. The causal relationship between the type IV sensitization to nickel and the occupation needs to be clarified in each individual case. In general, occupationally caused nickel allergy is rare and the occupational relevance of nickel allergy is often overestimated.