Many automobile manufacturers have developed lists of material which must be reported, restricted or prohibited entirely. Nickel, in the metallic and alloy forms, is generally not restricted but its use may have to be reported. The question has been raised whether certain applications of nickel in automotive applications, where it may come in contact with human skin, are appropriate.
"Nickel Directive" of the EU
In 1994, the European Parliament and the Council of the European Union passed a Directive on nickel which recognized that "the presence of nickel in certain objects coming into direct and prolonged contact with the skin may cause sensitization of humans to nickel and may lead to allergic reactions".
Member States were required to pass national legislation necessary to comply with Directive 94/27/EC, that nickel may not be used:
In products intended to come into direct and prolonged contact with the skin such as:
- necklaces, bracelets and chains, anklets, finger rings,
- wrist-watch cases, watch straps and tighteners,
- rivet buttons, tighteners, rivets, zippers and metal marks, when these are used in garments
If the rate of nickel release from the parts of these products coming into direct and prolonged contact with the skin is greater than 0.5 :g/cm²/week in a standard sweat test.
The nickel industry supports the objectives of Directive 94/27/EC in reducing the incidence of nickel allergy and nickel allergic contact dermatitis. Controls on the use of nickel-containing articles should be based on an assessment of the level of potential nickel release and the duration and nature of exposure, not on nickel content.
Despite the fact that the EU Nickel Directive was intended for articles such as jewelry which are "intended to come into direct and prolonged contact with the skin", it appears to have been recently adopted by some automakers in their restricted substances lists.
Is the Nickel Directive Relevant?
The basis of the EU Nickel Directive is that for a nickel-containing product to be a possible cause of allergic contact dermatitis it needs both to be used in close and prolonged contact with the skin and to release considerable amounts of nickel when in such contact. All common nickel-containing grades of stainless steel show very low nickel release rates in sweat tests and hence should cause no concern in any skin contact applications. (The exception might be certain sulphur-containing machinable grades, such as type 303 stainless steel. Use of these grades should be assessed with care.)
Nickel metal, some copper-nickel alloys, and some nickel-plated articles may release more nickel in simulated sweat and abrasion (EN1811:2011 and EN12474:2009) than is recognised as permissible under the nickel directive. Therefore it would be inappropriate for such products to be used where they can be expected to be in close contact with the skin for prolonged periods.
In the automotive industry, nickel-chromium plated components are widely used on substrates such as aluminium, plastics, zinc alloy and steel. Many, including wheels, door handles and trim are external and unlikely to be "routinely touched". Plated interior parts such as door handles, switches, gear shifts and seat belt fasteners may be routinely touched in normal use, but the skin contact is expected to be brief and intermittent. The use of nickel-chromium coatings to ISO specifications is very appropriate.
We continually encounter products with similar types and frequency of exposure in daily life (eg) door handles, cabinet furniture, tapware, bathroom fittings, domestic appliances and consumer electronics. Such products are ubiquitous and our contact opportunities enormous. Routine touching is not "direct and prolonged" contact with the skin. There is no evidence such routine touching of nickel-chromium plated products leads to allergic contact dermatitis.
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