The cost of nickel allergy: a global investigation of coin composition and nickel and cobalt release

Background. Nickel is widely used in coins; nickel may cause contact allergy and allergic contact dermatitis in those who handle them. Objectives. To investigate alloy use, coin composition and nickel and cobalt release for a worldwide selection of currently circulating coins. Materials and methods. Eight hundred and fifty coins of 361 different denominations or issues from 52 countries were collected and analysed with X-ray fluorescence spectrometry and nickel and cobalt spot tests. Results. Copper-nickel was the most frequently identified coin alloy, being observed in 100 denominations (28%), followed by aluminium-bronze (62, 17%). In total, 239 denominations released nickel (28%). Coins from Bolivia, Brazil and Costa Rica did not release nickel. Fewer than one-third of the denominations or issues from China, India, the euro area and Indonesia released nickel. In the United States, the Russian Federation, Japan, and Mexico, one-third or more of the denominations released nickel. Conclusions. This worldwide selection of circulating coins covered countries with 75% of the world population, and shows that the majority of the world population lives in countries where coins release nickel. Pertinently, ∼ 40% of circulating coin denominations do not release nickel.