Many human problems arise due to the ability of metallic gold to induce allergic contact hypersensitivity. While gold in jewelry can cause allergic reactions, other metals such as nickel, chromium and copper found in white gold or alloys present more serious clinical problems. While the list of retailers aligned in their opposition to dirty gold continues to grow, most gold is still quite dirty. Most of the world's gold is extracted from open pit mines, where huge volumes of land are extracted and processed for trace elements.
Earthworks estimates that, to produce enough raw gold to make a single ring, 20 tons of rock and soil are extracted and discarded. Much of this waste contains mercury and cyanide, which are used to extract gold from rock. The resulting erosion clogs streams and rivers and can eventually contaminate marine ecosystems deep below the mine. Exposing the depths of the earth to air and water also causes chemical reactions that produce sulfuric acid, which can seep into drainage systems.
Air quality is also compromised by gold mining, which releases hundreds of tons of elemental mercury into the air every year. The health problems of gold miners who worked underground include the decrease in life expectancy; the increase in the frequency of cancers of the trachea, bronchi, lung, stomach and liver; the increase in the frequency of pulmonary tuberculosis (PTB), silicosis and pleural diseases; the increase in the frequency of insect-borne diseases, such as malaria and dengue fever; the loss of noise-induced hearing; the increase in the prevalence of certain bacterial and viral diseases; and diseases of the blood, skin and the musculoskeletal system. These problems are briefly documented in gold miners in Australia, North America, South America and Africa. In general, HIV infection or excessive consumption of alcohol and tobacco tended to aggravate existing health problems.
Miners who used elemental mercury to amalgamate and extract gold were heavily contaminated with mercury. Among those exposed for work reasons, mercury concentrations in the air, fish diet, hair, urine, blood and other tissues significantly exceeded all criteria proposed by several national and international regulatory bodies for the protection of human health. However, large-scale epidemiological evidence of serious Mercury-related health problems could not be demonstrated in this cohort.