Nickel sensitivity in Singapore.

Nickel is the most common cause of allergic contact dermatitis in Singapore, resulting in positive reactions in patch tests between 7 and 14%. Women are more commonly affected and have an earlier mean age of onset than men (21 compared with 32). Wrist watches, earrings, buttons, and necklaces are the common source of nickel allergy. Twenty-five percent of patients also had some form of associated hand eczema. Thirty-six percent of patients had a history of atopy showing a higher incidence than the normal populations. Thirty-seven percent of patients had an associated positive reaction to cobalt.