Contamination by nickel, copper and zinc during the handling of euro coins

Abstract

The introduction of the euro has revived interest in the risk of nickel allergy due to the handling of coins. In the present work, the transfer of metallic contamination during the manipulation of coins is examined by means of leaching experiments and manipulation tests. It is shown that pre-existing metallic species present on the surface of the coins are the major source of contamination during manipulation, and that friction inherent to everyday usage contributes predominantly to their transfer to the hands. The comparison of coins as to their relative risks of metal contamination should therefore rely on tests that simulate the friction inherent in everyday human handling. Carrying out such tests with the newly issued 1 euro and 2 euro pieces, we find, contrary to long-term leaching measurements, that the euros release less nickel than previously circulated pure-nickel coins, but that this decrease is less pronounced than might have been hoped for on the basis of their surface composition. When the coins are rubbed to a shiny polish before manipulation, contamination of the fingers is reduced by more than a factor of 10. A comparison of coins used in France indicates that the introduction of the common currency has led to a fourfold reduction in contamination by nickel, while causing a 45% increase in contamination by copper.

Euro coins and the potential risk of nickel allergy

“…Such polishing reduces contamination upon subsequent handling by more than a factor 10, indicating that it removes more than 90% of accessible pre-existing contamination [12]. The results obtained for several types of nickel containing coins are summarized in table 2.…”

“…The contamination transferred to the fingers consists mainly of pre-existing species, rather than compounds generated during manipulation [12]. This is illustrated by fig.…”

“…Note that a significant amount of copper is transferred when manipulating pure-nickel francs. We ascribe it to the contamination of the pure-nickel pieces upon contact with copper-containing coins in daily usage.The contamination transferred to the fingers consists mainly of pre-existing species, rather than compounds generated during manipulation [12]. This is illustrated by fig.…”

“…The amount ofpre-existing metallic species accessible to contaminate the fingers can be evaluated by rubbing the coins to a shiny polish and determining the amount of metal recovered on the "wipes" used to do so [12]. Such polishing reduces contamination upon subsequent handling by more than a factor 10, indicating that it removes more than 90% of accessible pre-existing contamination [12].…”

“…Details ofthe procedure can be found in references [7] and [12]. Table 1 summarizes the results of such tests carried out by 3 people counting three sets of25 used coins each: bi-metallic euros (12 pieces of 1€ and 13 of2€), Cu75Ni25 copper-nickel coins (2SFr), and pure-nickel2FF pieces.…”