Top 10 Worst Environmental Disasters

Baia Mare Cyanide Disaster Baia Mare, Northwestern Romania January 30, 2000

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In removing the last remnants of gold and silver from discarded mine tailings, AURUL, an Australian-Romanian joint venture, used a cyanide-based “heap leaching” method to more purely extract the precious metals. This technology, usually used in sealed vats – or in the case of Baia Mare, on large exposed piles of waste rock – enables miners to re-mine waste materials for very small concentrations of precious metals. In 2000, a dam used to isolate the cyanide-laced water near Baia Mare failed, and sent 100,000 cubic meters of toxic water into the Szamos and Tisza rivers, which flows toward Hungary. Shortly after the incident, Romanian officials found cyanide levels 700 times above normal in nearby river water and Hungarian officials measured cyanide levels 300 times above the threshold of the Hungarian pollution standards. Copper concentrations exceeded the pollution threshold by 40 to 160 times, the zinc concentration was twice the standard and the lead concentration 5 to 9 times greater than the standard.