Nickel is the most frequent cause of contact allergy. At least 10-15% of women and 2-5% of men are allergic to nickel, and 30-40% of nickel-sensitive people develop hand eczema which may often be chronic with far-reaching consequences for both the individual and the society.

The Nickel Directive
The EU Nickel Directive was adopted in 1994, and it entered into full force in July 2001. The aim is to prevent sensitisation and also elicitation of allergic contact dermatitis. Nickel is limited:

(1) in posts used during epithelization after piercing (nickel content below 0.05%);
(2) in objects intended for direct and prolonged contact with the skin, such as jewellery, watches, buttons, zippers etc. (nickel release below 0.5 microgram/cm2/week);
(3) coated items under (2) must fulfil the criteria after ”two years of normal use”.

Test methods for nickel – European standards
CEN/TC 283/WG 4, convened by Sweden, has under a European Commission mandate developed the three reference test methods for showing compliance with the demands of part 1-3 of the Nickel Directive:

(1) EN 1810 – Nickel content by atomic absorption spectroscopy
(2) EN 1811 – Nickel release, one week in artificial sweat
(3) EN 12472 – Wear and corrosion test

The screening test for nickel release based on dimethylglyoxime (DMG) and ammonia has been further developed (CEN TR 12471). It has been made more sensitive and more specific than the simple DMG test. The standard describes a pre-test (the simple DMG test), a field application, and a laboratory application. The test is quick, cheap and simple to perform. It may be used by producers, retailers, consumers and authorities, as a guide concerning nickel release.

Effects of regulation
Denmark has since 1989 had a regulation limiting nickel release, similar to part 2 of the Nickel Directive. In Denmark, reduced sensitisation to nickel has been recorded among dermatitis patients (Duus Johansen J et al. Br J Dermatol 2000;142:490-5), and in schoolgirls with pierced ears (Jensen CS et al. Br J Dermatol 2002;146:636-42). This has been interpreted as a result of the regulation.

In Sweden, the market has started adaptation to the Nickel Directive (part 2) as shown by a study performed in 1999, two years before full entry into force. The largest market holders were aware of the coming demands and tried to introduce nickel policy in their quality control system. 25% of 725 items tested with the simple DMG test were positive, and would not comply with the demands (Lidén C et al. Contact Dermatitis 2001;44:7-12).

Conclusions
Prevention of nickel allergy is of great concern. The EU Nickel Directive limits nickel in certain items known to be the most important causes of sensitisation. Part 2 of the Directive, limitation of nickel release from items in direct and prolonged contact with the skin, has already been shown to have an impact.

The nickel allergy problem will hopefully be much reduced in the future, provided that the market adapts to the requirements of the Nickel Directive. Information to increase understanding of the problem and effective control will be needed.