Health Impact of Artisanal Gold Mining in Latin America

Gold in hard rock is chemically bound to the ground rock. In industrial operations, gold is released by crushing the ore into a fine powder, then mixing it with sodium cyanide to bind to the gold to separate it. The cyanidation process, currently used in 90 percent of gold production, remains controversial due to the toxic nature of cyanide. However, unlike mercury, cyanide is degradable and does not accumulate in animals as it moves through the food chain. In Latin America, most artisanal miners do hard rock mining, primarily in small underground mines that they operate themselves or industrial mines that have been abandoned. Hard rock artisanal miners are more likely to use mercury than cyanide to harvest their gold.
http://revista.drclas.harvard.edu/publications/revistaonline/winter-2014/health-impact-artisanal-gold-mining-latin-america