The technique using dissolution with alkaline cyanide has been highly developed over recent years. It is particularly appropriate for low grade gold and silver ore processing (e.g. less than 5 ppm gold) but its use is not restricted to such ores. There are many environmental hazards associated with this extraction method, largely due to the high acute toxicity of the cyanide compounds involved. A major example of this hazard was demonstrated in the 2000 Baia Mare cyanide spill, when a break in holding pond dam at a mine waste reprocessing facility near Baia Mare in northern Romania released approximately of waste water contaminated with heavy metal sludge and up to of cyanide into the Tisza River. As a consequence, most countries now have strict regulations for cyanide in plant discharges, and plants today include a specific cyanide-destruction step before discharging their tailings to a storage facility.