Background

• Nickel is trace element that is necessary for the survival of bacteria, plants, and mammals. It is a hard, bright, silver-white metal that is present in soil, water, cocoa and chocolate, nuts, dried beans, peas, soya beans, spinach, lettuce, oatmeal, grains, fruits (including canned fruits), other vegetables (including canned vegetables) and leguminous seeds, as well as shellfish, salmon, hydrogenated shortenings, eggs, and milk. Drinking water and food are the main sources of nickel. The average American diet contains about 300 micrograms of nickel daily.
• Nickel alloys are metals created by combining nickel with another metal, such as titanium, and are used in many medical and dental applications, including dentures, dental crowns, stents, hip replacements, and screws used during bone reconstruction surgery. Nickel is also used to manufacture stainless steel. It is a common component of silver coins, belt buckles, and inexpensive jewelry. It is used in the automobile industry, electronics, chemical processes, nickel-cadmium batteries, and many household products.
• Nickel is the most common cause of metal allergy, which affects females more often than males. It may develop at any age and tends to last throughout an individual's lifetime. Symptoms of nickel allergy include an itchy rash at the site where nickel contacted the skin. This reaction may occur after chronic exposure to nickel-containing products, such as eyeglass frames, dental materials, and inexpensive jewelry. Human exposure to highly nickel-polluted environments, such as those associated with nickel refining, electroplating, and welding, may cause skin allergies and cancer of the nose and lung.
• The European Union Nickel Directive limits the amount of nickel allowed in consumer products that come into direct and prolonged contact with the skin (e.g., earrings, watchbands, and zippers). There are some indications that this regulation has reduced the amount of nickel allergy in Europe. In North America, where no regulations are in place, the incidence of nickel-induced skin allergy is increasing. Some experts believe that regulations should be in place in the United States and other countries to prevent unnecessary nickel allergies.
• Although nickel deficiency may theoretically exist, scientific evidence of any benefit from nickel supplementation in humans is lacking in the available literature.

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