Metal sulfide formation on United States coins after hydrogen sulfide exposure.

INTRODUCTION

There are limited real-time diagnostics available to confirm human exposure to hydrogen sulfide outside of on-scene gas detection. The presence of tarnished metal may be used by first responders when assessing the likelihood of exposure.

CASE SUMMARY: During a regional hazmat drill, we evaluated the change in appearance of United States coinage exposed to hydrogen sulfide at >6,000 ppm in an enclosed motor vehicle.

IMAGES: Coins were photographed before and after the hazmat drill. Those coins exposed to the ambient environment blackened completely on the surface exposed, while coin surfaces shielded by clothing or facedown were tarnished to a lesser degree.

DISCUSSION: United States pennies are copper-plated, and silver-colored coins are surfaced with cupro-nickel alloys. Copper is highly reactive with hydrogen sulfide. Metal sulfide formation is impacted by metal reactivity, temperature, and humidity.

CONCLUSION

Copper sulfidation of United States coins may be a clue to the diagnosis of hydrogen sulfide exposure for on-scene responders.