Quantitative aspects of nickel dermatitis. Sensitization and eliciting threshold concentrations

Nickel is the most common cause of contact allergy among females. A recent Danish population study found 11.1% of the females and 2.2% of the males nickel-sensitized. Primary nickel sensitization is caused by well-defined nickel exposures. Trace amounts of nickel present in the general environment don't induce nickel sensitization. Based on a wide range of studies, an arbitrary non-sensitizing nickel concentration of 0.5 microgram/cm2/week has been suggested for consumer items made of nickel alloys. Eliciting of nickel dermatitis is unlikely for concentrations < 0.1-1 microgram/cm2 during occluded exposure and 15 micrograms/cm2 when non-occluded. The effect of repeated exposures to normal skin is unexplored. Highly sensitized individuals might react to 0.5 ppm nickel (0.0075 microgram/cm2) when exposed on inflamed skin under occlusion. It is concluded that most cases of nickel allergy/nickel dermatitis are preventable without interfering with the quality of life or imposing economic costs to society.