Gold’s Hidden Glitter: Mercury Use in Artisanal and Small-Scale Gold Mining

When James W. Marshall first struck gold in California’s Sacramento Valley, it became a universal symbol of opportunity, wealth, and new beginnings. More than 170 years later, this sentiment still exists around the globe. According to the United Nations Environment Programme (UNEP), artisanal and small scale gold mining (ASGM) produces up to 20% of the world’s gold, employing 10 to 15 million people in mainly rural areas. While ASGM creates economic opportunities for low-income people in over 70 countries, the mercury that is used in the gold extraction process causes environmental and health problems. 

Mercury is a naturally occurring chemical element found in the Earth’s crust. It comes in three forms: elemental mercury, inorganic mercury, and organic mercury. Elemental mercury, also known as quicksilver, is a shiny, silverish-white liquid metal that’s typically associated with old thermometers.  Inorganic mercury can combine with chlorine, sulfur, and other elements to form inorganic mercury salts, which are used and emitted into the environment by coal power plants, the burning of medical and municipal waste, and factories that use mercury.  Organic mercury forms when microscopic organisms combine inorganic mercury with carbon.  Methylmercury is one of the most common, toxic forms of organic mercury, and infiltrates many large fish populations. 

Mercury is an inexpensive and easy way to collect gold, and the process has hardly changed since it was first utilized centuries ago.  First, a mixture of water and sediments is collected from a waterway.  Then, elemental mercury is added, which combines with gold and forms an amalgam.  Finally, the mercury-gold mixture is burned, releasing mercury into the environment through airborne vapors or in leftover sediment. This process leaves behind gold particles ready to be made into jewelry, electronics, smartphones, etc.  The convenience of the process is why ASGM is the largest intentional use of mercury in the world, responsible for 837 tonnes of mercury emissions and 38% of total emissions in 2018. 

According to the World Health Organization (WHO), mercury is considered one of the top ten chemicals or groups of chemicals that pose a major public health concern.  During the gold extraction process, mercury vapor inhaled by miners can result in major neurological damage, impaired cognitive function, kidney damage, and several other health problems. In many cases, mercury-gold amalgams are burned in gold shops, extending the risks of mercury to shop workers as well. According to chemists Louisa Esdaile and Justin Chalker, “For children and fetuses, exposure to mercury pollution is especially dangerous as it increases the likelihood of physical deformities, neurological damage and lower IQ.”  Even though children are more susceptible to mercury’s consequences, they remain a large part of the gold extraction processes.  A 2018 field study conducted by Human Rights Watch found that thousands of children have been unlawfully exploited in Ghana’s ASGM industry due to lax enforcement of the law and a lack of systematic inspections.

Beyond the initial health effects of mercury suffered from those involved in the ASGM industry, even those who are far removed from this process can be affected.  According to the New Hampshire Department of Environmental Services, “Once it is released into the atmosphere, mercury can travel hundreds of miles with the wind before being deposited on the earth’s surface. Deposition can occur in as little as five to fourteen days after mercury is emitted to the air, or it can take approximately one year – during which time mercury can reside in the air and be transported far around the globe.”  Once deposited, this toxic element makes its way into the food chain and onto our plates.  This inorganic mercury can be absorbed by algae, which is consumed by small fish in various bodies of water. As these smaller fish are consumed by larger fish, mercury transfers up the food chain in a process called bioaccumulation. This process explains why larger fish have significantly higher levels of mercury. Regular consumption of large fish can cause mercury poisoning, with health effects similar to those who inhale mercury vapors. 

Mercury poisoning isn’t just a concern for humans; it disrupts ecosystems as well. Just as mercury causes reproductive, neurological, and developmental problems for humans, it does the same to fish.  Animals whose diets are reliant on fish, like loons, eagles, and otters, ingest mercury. Even mountain lions in California are exhibiting high levels of mercury due to lichens present in their ecosystem that absorb inorganic mercury.  The rainforests where ASGM takes place are also experiencing detrimental levels of deforestation.  To mine enough gold for a simple 18-karat wedding band, 30 tons of rock and biomass waste are produced. ASGM has destroyed more than 170,000 acres of primary rainforest in the Peruvian Amazon from 2013-2018, according to a new analysis by scientists at Wake Forest University’s Center for Amazonian Scientific Innovation (CINCIA).  

Many argue that the economic benefits of gold mining outweigh the negative health and environmental impacts.  According to the World Gold Council, gold mining companies contributed over 171.6 billion U.S. dollars to the global economy in 2013.  They also claim that 70 percent of expenditures are devoted to paying workers and suppliers in host countries, bolstering the economies of low and middle income countries.  However, the economic benefits of reducing mercury emissions far surpass the economic benefits of ASGM.  According to an MIT study, the Minamata Convention on Mercury, an international treaty signed by 140 countries to phase out mercury across many industries, would lead to 339 billion dollars in economic benefits by 2050 in the U.S. alone. These economic benefits would be a result of reduced healthcare costs and more economic productivity, because mercury causes reduced mental function.  

So the question remains: what can be done to stop mercury use in ASGM? While the Minamata Convention was a significant step in the right direction to curb mercury emissions, many countries have lax enforcement policies or are unable to trace illegal mining activities because miners and mining sites are constantly on the move. One solution is phasing out mercury use in ASGM all together. According to the EPA, concentration methods, which use gravity, magnets, or chemical properties to separate gold from sediments, can be used as alternatives to mercury.  “Alternatives should be affordable, cleaner and more efficient at extracting gold, a combination that is well recognized by international agencies, governments, NGOs and academics. However, such a major change in processing requires continuous efforts in formalization, education and organization of miners. Bottom up approaches, involving the miners, are essential,” says UNEP.   

One individual taking a bottom up approach is Marcello Veiga, a mining engineering professor at the University of British Columbia. Viega travels to ASGM sites and educates miners through mercury-related song parodies. “It’s the way to get the guys laughing. This is the best way to educate them about the dangers of mercury pollution,” says Viega.  Planetgold is another organization that takes a bottom up approach in addressing the dangers of ASGM.  Led by UNEP, Planetgold works with governments, the private sector, and ASGM communities in 9 countries to improve production practices and work environments of ASGM workers. Planetgold educates miners to achieve a mercury-free industry, and also facilitates miners’ access to formal gold supply chains to prevent their exploitation.  

Innovative approaches like those of Viega and Planetgold are a step in the right direction to ensure that ASGM doesn’t continue to threaten environmental and public health.  However, working towards a mercury-free gold industry can and should not be a responsibility solely reserved for miners.  A world where mercury isn’t a threat will need to involve change at all steps of the ASGM process, from sediment to storefront.  


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