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.