Many chemical agents, including nickel, can cause allergic contact dermatitis (ACD) which results in inflammation of areas of the skin in sensitized individuals. While nickel ACD can cause pain, inflammation and discomfort, it is not life threatening because it causes a delayed-type allergy (type 4), which cannot trigger anaphylactic shock like some other types of allergies (type 1, 2, or 3).
Elemental nickel and sweat-soluble nickel salts both cause ACD by solubilization of nickel substances and the formation of nickel ions, during intimate and prolonged contact with the skin and sweat. The rate of nickel ion release to the skin is dependent primarily on the specific substance having contact with the skin. Non-occupational exposure to nickel in Europe, primarily through jewelry in piercings (e.g., earrings) and direct and prolonged skin contact with nickel-releasing jewelry, clothing fasteners, etc. has reportedly sensitized from 12-15% of females and from 1-2% of males.
The nickel industry supports the intent of legislation such as the European Union's Nickel Directive (94/27/EC as amended), now subsumed into the REACH Regulation Annex XVII. This prohibits the use of nickel in products intended for direct and prolonged skin contact if this will result in solubilization of nickel at a rate exceeding 0.5 micrograms per square centimeter per week or in the case of body piercing, a lower rate of 0.2 micrograms per square centimeter per week (as measured by EN1811 testing). Furthermore, the nickel industry accepts the expert opinion of dermatologists who state that such a regulation is expected to reduce the prevalence of nickel sensitization incidence of nickel ACD in the general population to very low levels.
There is no justification for banning nickel from uses in general consumer products unless there is clear evidence, resulting from a detailed risk assessment, that such a use poses a significant health risk. The Danish EPA (Environmental Protection Agency) conducted a target risk assessment on nickel as used in euro coins.(1) The conclusion of this report for consumers was: “There is at present no need for further information or testing or risk reduction measures beyond those which are being applied already.” The use of nickel in coinage does not pose a health risk for the majority of the general population because this application does not involve direct and prolonged contact with the skin under normal handling and use. Many populations, including North Americans, that have used nickel in coinage for many decades show few cases of nickel ACD associated with coins.
The use of most stainless steel alloys in consumer products does not constitute a health risk for nickel ACD. This is be-cause most stainless steels have not been demonstrated to cause nickel ACD in nickel-sensitized individuals, nor do they release sufficient amount of nickel ions. In addition, such items would not come into contact with the skin at the required intimacy or for the required time to cause nickel sensitization reactions.
The nickel industry will continue to be supportive of scientific research on the mechanism of nickel sensitization, improving tests for nickel sensitivity, and conducting studies to ensure that nickel-containing materials are used in appropriate applications.
While technical in nature, this is not a peer-reviewed science paper. It is intended to be an overview of a topic that has generated very extensive literature over a long time period.
1. Danish EPA (Environmental Protection Agency). 1999. Risk Assessment Targeted Report: Nickel as Used in Euro Coins. Draft of 2, June. CAS No. 7440-02-0, EINECS No. 231-111-4.