Laying an alloy ‘egg’

• Book ID: 104415749
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 46 KB
• Volume: 5
• Category: Article
• ISSN: 1369-7021
• DOI: 10.1016/s1369-7021(02)01113-6

✦ Synopsis

Their investigation reveals that 1 and 2 coins release sufficient nickel to induce an allergic reaction in sensitive individuals after prolonged contact [Nature (2002) 419, 132].

Part of the problem is the bimetallic structure of these coins, say the researchers. The 1 coin consists of a yellow nickel-brass ring and a white cupro-nickel inner 'pill'; while a cupronickel ring and nickel brass pill make up the 2 coin. In human sweat, the bimetallic structure generates a galvanic potential of 30-40 mV. The resulting corrosion of the alloys releases nickel at a level exceeding that acceptable for prolonged contact with skin. Whether this contravenes European Union directives depends on how 'prolonged' contact is defined, say the researchers, but further investigated is warranted.