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Keywords:

  • contact dermatitis;
  • Euro;
  • nickel

Starting from January 2002, the Euro has become the official monetary unit of the European Union and has replaced the various national currencies. It has been recently demonstrated that the 1 and 2 euro coins release very high amounts of nickel, at variance with the 50 and 10 cent coins. This has been attributed to the peculiar bimetallic structure of the 1 and 2 euro coins (that are composed by a ring and a central plate of different cupro-nickel alloys): the bimetallic structure generates a galvanic potential that is responsible for corrosion and nickel release in contact with human sweat (1). The release of nickel has been found to exceed by about 300-fold the limits recommended by the European Union. Thus, it has been claimed that handling Euro coins can lead to an increase of the prevalence and severity of contact dermatitis caused by nickel.

We attempted to test the hypothesis that the current handling of Euro coins has increased the rate of nickel sensitization. This was performed by studying two large groups of patients referring for suspected contact dermatitis. The first group was studied before the introduction of the Euro (i.e. before January 2002), and the second group from January 2002, when the new currency was introduced.

More than 1000 consecutive outpatients suspected of contact dermatitis underwent a patch test with the European Standard Series (2). All the patients had an eczema strictly confined to both hands. Patients pierced at any body site were excluded from this analysis in order to avoid a heavy confounding factor, as it has been shown that the presence and number of piercing increases the rate of contact allergy (3). Demographic data, working habits and the history of allergic diseases were carefully recorded in all patients. In particular, the patients were screened by clinical history for the presence of one or more of the following: hayfever, allergic asthma, atopic dermatitis, food or drug allergy, hymenoptera venom hypersensitivity.

A total of 753 patients were patch-tested before January 2002, and 252 after that month. The characteristics of the two groups of patients are summarized in Table 1.

Table 1.  Characteristics of the patients patch-tested before and after the introduction of euros
 Before EuroAfter EuroP (χ2)
Patients753292 
Sex (M/F)273/48076/216NS
Mean age4342.5NS
Age range15–8114–82NS
History of allergic diseases122 (16.2%)50 (17.1%)NS
Patch-test nickel positivity202 (27%)78 (26%)NS
Age range15–7614–72NS
History of allergic diseases39 (19.2%)15 (19.6%)NS

It is worthy of note that there was no difference at all in the rate of positivities to nickel sulphate between the two groups (27% vs. 26%, chi-square test, P = NS), although the two groups were well matched for their general characteristics. As expected, according to the existing literature, the positivities to nickel were largely more frequent in women than in men, and the prevalence of atopic diseases was around 20%.

Based on the data from the literature, indicating that some euro coins release high amounts of nickel, an increased occurrence of nickel sensitization and contact dermatitis should be expected after the new currency has been introduced (4). Nevertheless, our data collected in a large population that can be considered a representative sample of what seen in the current clinical practice do not confirm the hypothesis. So far, after about 2 years of use of Euro, no increase in nickel sensitizations could be detected in the general population referring for hand dermatitis. This reassuring datum is probably because of the fact that in everyday life, the direct contact with the metal of coins is not prolonged enough to make the increased nickel release clinically significant. In this regard, it has to be taken into account that nickel release experiments were made under artificial conditions (artificial sweat) (1), whereas short-term handling does not increase the release of metals (5). Indeed, in our population there was no subject that could be considered ‘at high risk’ for prolonged and continuous handling of coins and metals, such as cashiers or jewellers (6), therefore we cannot exclude that in very selected patients, with specific working habits, the use of the new coins can lead to increased occurrence or worsening of contact dermatitis.

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