Abstract

Objectives: This study investigated whether coins of the new European currency (€) corrode when they are exposed to gastric acid, and whether this change can be detected radiographically.

Methods: The eight different denominations of € coins were immersed for seven days in 0.15 N hydrochloride acid (HCl), which corresponds to the level of post-prandial gastric acid. A Swedish crown coin and three different Austrian schilling coins were used as controls. The coins were weighed and radiographed daily to evaluate visible corrosions and HCl was analysed daily for possible dissolved substances.

Results: All coins lost weight within 24 hours after exposure to HCl. The 1, 2, and 5 € cent coins developed changes that were visible on radiographs. The weights of all coins decreased by 0.43% to 11.30% during one week. The dissolved substances measured in the HCl corresponded to the different metals and alloys of the coins, except for copper, which does not dissolve in HCl. The highest absolute weight loss was observed in the Swedish crown coin (0.67 g), and the highest relative weight loss in the 1 Austrian schilling coin (11.30%). The two € coins that showed the highest absolute and relative weight losses were the 2 € (0.54 g or 6.35%) and the 1 € (0.48 g or 6.39%) coin.

Conclusions: A higher rate of toxicity for the new European coins compared with coins of other currencies is not expected, unless a massive coin ingestion occurs.