Gastric retention of zinc-based pennies: radiographic appearance and hazards.

PURPOSE: To determine the radiographic appearance and features of corrosion in U.S. coins exposed to gastric acid.

MATERIALS AND METHODS: Six U.S. copper-based pre-1982 pennies, 12 zinc-based post-1982 pennies, a quarter, a nickel, and a dime were exposed to postprandial concentrations of gastric acid (0.15N HCl) for 7 days, and radiographs were obtained daily. Half the zinc-based coins were scraped to disrupt their copper coating. Coins were weighed at the start and completion of the study.

RESULTS: Post-1982 zinc-based pennies developed radiolucent corrosive changes within 24 hours. Erosions on the coins became more apparent over time. Frank holes were present on day 2. The weights of these coins decreased 5%-8% during the study. Pre-1982 copper pennies and "silver-colored" coins showed no change on radiographs over 7 days.

CONCLUSION: Unexpected radiolucent corrosions may develop in post-1982 zinc alloy pennies when retained in the stomach. Coins have long been considered innocuous foreign bodies in the gastrointestinal tracts of children. However, because of the potential for ulceration and zinc-related morbidity, closer clinical and radiographic observation is warranted. Coins with scalloped edges or holes should be endoscopically removed, as they have likely been retained longer than 1 or 2 days.