BACKGROUND: Knowledge about the required duration of exposure for elicitation of allergic nickel dermatitis in nickel-allergic individuals is limited. However, it often has been proposed that short skin contact is safe.

OBJECTIVES: To examine whether repeated skin contact with nickel over short time periods (3 × 10 min) can elicit allergic nickel dermatitis.

METHODS: Sixteen nickel-allergic adults and 10 controls were exposed to, respectively, nickel- and aluminium-containing discs on each volar forearm and on each earlobe for 3 × 10 min. One arm was pretreated for 24 h with sodium lauryl sulfate (SLS) 0·5% under occlusion before exposure. One aluminium and one nickel exposure site were clinically evaluated, and blood flow was measured with laser Doppler flowmetry at day 2 and day 4.

RESULTS: Ten of 16 (63%) nickel-allergic participants developed allergic nickel dermatitis on SLS-pretreated arm skin and three of 16 (19%) developed it on normal skin on the earlobe. On the SLS-pretreated arms of nickel-allergic participants, blood flow increased significantly more on the nickel-exposed skin than on the aluminium-exposed skin on days 2 and 4. No change in clinical reactivity or blood flow was found on normal forearm skin in nickel-allergic participants or on any skin in controls.

CONCLUSIONS: This experimental study showed that relatively short repeated skin contact (3 × 10 min) with metallic nickel elicits allergic nickel dermatitis in irritated skin and at sites with previous dermatitis. The results support the restrictions in current nickel regulation.