Short Repeated Nickel Exposures

"All participants will be exposed to 8 metal discs, 3 cm in diameter, 4 on each arm, placed on the volar side of the forearms (figure 1). Three of the metallic discs consists of \>99 wt.% nickel one consist of \>99wt.% Aluminium.The latter is used as a negative control. The discs will be applied under occlusion and with initial pressure and friction.~One metallic disc with nickel, and one with aluminium, will be randomized for the earlobes on the patients with nickel allergy"