Solve pollution. Save lives. Protect the planet.

Mercury attacks the central nervous system, affects brain functioning and, in extreme cases, exposure will lead to death.

Despite being commonly overlooked, industrial pollution still poses a significant threat to human health, particularly in the case of artisanal gold mining.

Global Toxic Pollution – Under the Radar

The fixation of industrialized nation on climate change has resulted in an unprecedented concern for the environment.  Although these admirable and impressive efforts have led to a mainstreaming of the issue of global warming, other pollution problems remain relatively unpublicized, despite being significant threats to our planet. Further, the most under-reported pollution problems are currently adding to the disease burden of people living in the Global South. Although wealthy nations have regulated industrial pollution within their borders, toxic emissions from industry and mining are still a major cause of disease and disability in developing countries. While significant steps have been taken by the global community to combat industry-related pollution as it relates to climate change, the issue of toxic pollution still remains relatively ignored throughout the Global South.

Industrial wastes, air emissions, and legacy pollution affect over a billion people around the world, with millions poisoned and killed each year. People affected by pollution problems are much more likely to get sick from other diseases. Other people have reduced neurological development, damaged immune systems, and long-term health problems. Women and children are especially at risk. The World Heath Organization estimates that 25 percent of all deaths in the developing world are directly attributable to environmental factors. According to a 2007 Cornell University study conducted by David Pimentel, about 40 percent of deaths worldwide are caused by air, water and soil pollution.

Widely under-reported, artisanal gold mining is one of the most significant sources of mercury releases into the global environment. In general, artisanal mining refers to mining activities that use rudimentary methods to extract and process minerals and metals within a community, as opposed to a large scale industrial operation. Artisanal miners also frequently use toxic materials in their attempts to recover metals and gems. Such miners work in difficult and often very hazardous conditions and, in the absence of knowledge or any regulations or standards, toxic materials can be released into the environment, posing large health risks to the miners, their families and surrounding communities[1]. In this context, gold mining operations are particularly dangerous, as they often use the mercury amalgamation process to extract gold from ores.


Most artisanal gold miners are from socially and economically marginalized communities, and turn to mining in order to escape extreme poverty, unemployment and landlessness[2]. The dangers force miners to not only risk persecution by the government, but also mine shaft collapses, and toxic poisoning from the variety of chemicals unsafely used in processing. Despite the many dangers of this activity, artisanal mining operations continue to spread as the demand for metals increases and other livelihoods such as farming, are no longer economically viable. UNIDO estimates that mercury amalgamation from this kind of gold mining results in the release of an estimated 1000 tons of mercury per year, which constitutes about 30 per cent of the world’s anthropogenic mercury emissions. It is estimated that there are between 10 and 15 million artisanal and small scale gold miners worldwide, including 4.5 million women and 600,000 children[3]. According to the United Nations Industrial Development Organization (UNIDO), as much as 95 percent of all mercury used in artisanal gold mining is released into the environment, constituting a danger on all fronts – economic, environmental and human health[4].

In a new Communities and Small-Scale Mining (CASM) publication, Somit Varma, director of the Oil, Gas, Mining & Chemicals Department of the World Bank/IFC stated, “The social and economic characteristics of small-scale mining fully reflect the challenges of the Millennium Development Goals, including: health, environment, gender, education, child labour, and poverty eradication.”


Artisanal gold mining is one of the most significant sources of mercury release into the environment in the developing world, with at least a quarter of the world’s total gold supply coming from such sources[5]. Artisanal gold miners combine mercury with gold-laden silt to form a hardened amalgam that has picked up most of the gold metal from the silt. The amalgam is later heated with blow torches or over an open flame to evaporate the mercury, leaving small gold pieces. The gaseous mercury is inhaled by the miners and often by their immediate family, including their children. Mercury that is not inhaled during the burning process, settles into the surrounding environment or circulates globally for future deposition far from the site, where it is absorbed and processed by a variety of living organisms. This transforms elemental mercury into methylmercury. Methylmercury is one of the most dangerous neurotoxins that contaminate the food chain through bioaccumulation.

Exposure Pathways

Artisanal gold mining releases mercury into the environment in its metallic form during amalgamation and as mercury vapor during the burning process. When metallic mercury is used to concentrate the gold, small amounts can be washed out along with the unwanted tailings or sediments. One study estimates that one or two grams of metallic mercury are lost for every gram of gold produced using the amalgamation process[6]. Once mercury is released into waterways, it enters the food chain through the digestion of bacteria and becomes the far more toxic – methylmercury. Methylmercury bioaccumulates in the food chain and is ingested by residents of downstream communities as they eat contaminated fish. The most direct pathway however, is the inhalation of mercury vapors created during the burning process. An immediate toxic exposure, miners and their families are most affected by these noxious vapors, particularly young children. Additionally, metallic mercury vapours are more harmful than other forms of mercury because in this form, more mercury reaches the brain and can result in permanent damage to the brain, kidneys and a developing foetus. A study of artisanal gold mining in Peru concluded that for every gram of gold that is produced, at least two grams of mercury are emitted into the atmosphere[7].

Blacksmith Mercury Projects

Blacksmith Institute, a New York-based non-profit organisation, designs and implements solutions for pollution related problems that impact human health in the developing world. Since 1999, Blacksmith has worked to clean up dangerous and largely unknown contaminated sites where human health is most affected by industrial pollution and pollution from mining. In its short lifespan, Blacksmith has completed over 50 projects and is currently engaged in over 30 projects in 14 countries, each with a particular focus on children’s health and development.

Each of Blacksmith Institute’s several mercury programmes around the world share a common objective: to introduce mercury-reducing technologies to artisanal mining communities in order to lessen the impact on human health and the environment. Blacksmith has initiated a series of appropriate technology demonstrations to limit the mercury emissions affiliated with artisanal mining. These projects, which emphasise the introduction of appropriate technology to capture mercury, are carried out in conjunction with UNIDO’s Global Mercury Project. Dr. Marcello Veiga, Chief Technical Advisor to the Global Mercury Project, developed a groundbreaking and inexpensive adaptation of retort technology, which can be made at little cost (between $3 and $8US), and prevent mercury from entering the environment while allowing the mercury to be reused.

Blacksmith Institute initiated the first in a series of appropriate technology demonstrations to reduce mercury emissions associated with artisanal mining in 2005 in Manica, Mozambique. Blacksmith’s first intervention sent Dr. Veiga, to Mozambique to train miners on how to use retorts to capture evaporated mercury. The project assessed mercury use and mining practices in the region, trained local government, miners and their families in mercury-reduction techniques, monitored usage and developed follow-up/replication plans. Blacksmith has continued to support the Mozambican Ministry for the Coordination of Environmental Affairs to identify and train staff who have continued to work with local miners.

Blacksmith has since collaborated with Global Mercury Project staff to conduct similar projects in Cambodia, Senegal and most recently Kalimantan, Indonesia.

Responsibility to Create Change

Artisanal gold mining poses a significant health risk that can be easily and cost effectively remedied to protect the health of the miners and the global environment. Artisanal mining is largely a subsistence activity, and the health risks associated with mercury are largely unknown to the miners. This is a tragic example of marginalized people in developing countries, bound to a toxic source of income, with little or no guarantee to provide a safe environment for their children. With the will to create change and the technology to make a difference, real strides can be made to help some of the poorest communities in the developing world. “Interventions are both possible and cost-effective,” said Blacksmith president, Richard Fuller; “the world can afford to pay attention to the pollution agenda – and it can’t afford not to.”

Mercury exposure

Short-term exposure to high levels of mercury vapors may cause effects including lung damage, nausea, vomiting, diarrhea, increases in blood pressure or heart rate, skin rashes, and eye irritation. Mercury attacks the central nervous system and effects on brain functioning may result in irritability, tremors, changes in vision or hearing and memory problems. In extreme cases, mercury exposure will be fatal. Furthermore, mercury is a trans-boundary pollutant. The mercury that is not inhaled in the heating process settles into the nearby environment and can circulate great distances.

Global Mercury Project

The Global Environment Facility, United Nations Development Programme (UNDP) and UNIDO-supported Global Mercury Project (GMP) was established in August 2002.

Six countries (Brazil, Lao PDR, Indonesia, Sudan, Tanzania and Zimbabwe) participated in a pilot project to remove barriers to the introduction of cleaner technologies for artisanal and small-scale mining. Other neighboring countries (including Venezuela, Ecuador, Mozambique and Guinea) in collaboration with Blacksmith Institute, also received some assistance.

In most of the pilot GMP project sites, agriculture was the main source of livelihood, but mining can often be the most significant source of wealth albeit with significant health costs. A survey conducted in the Kadoma-Chakari area of Zimbabwe indicated that while mining represents an important component of the economy, farming is the main source of income, and many people are engaged in mining on a part-time or seasonal basis (23 per cent). Part-time miners are often engaged in farming during the rainy season when mine shafts and pits fill up with water and are at risk of collapsing. In the area surveyed about 34 per cent of the people work full-time in mining (predominantly mill workers whose work is not hindered by heavy rainfall) while 20 per cent work in farming on a full-time basis and 7 per cent of people were working in other occupations. In 2006, the average income in the area was equivalent to about US$49/month.

GMP was introducing best practices and pollution prevention measures to limit mercury contamination from small-scale mining. As a practical measure it promoted the use of a retort that can be made locally from inexpensive materials and developed in collaboration with the University of British Columbia’s Department of Mining Engineering. Training programs helped to make miners sensitive to the health risks and adopt new practices.

International guidelines were prepared to minimize mercury use in small-scale mining and reduce environmental and occupational hazards. Provisions include: mercury emission and exposure controls; recycling and reusing mercury; reduction of mercury in tailings; prevention of combined uses of mercury and cyanide; constraints on where mercury is used (emphasizing protection of village/residential areas and water sources); safe storage, disposal, clean-up and rehabilitation; guidelines to manage mercury in gold shops; and conducting environmental and health assessments.


[1] Hilson, Gavin; Hilson, Christopher J.; and Pardie, Sandra. “Improving awareness of mercury pollution in small-scale gold mining communities: Challenges and ways forward in rural Ghana.” November 13, 2006.

[2] Tschakert, Petra and Singha, Kamini. “Research on Smal-Scale Gold Mining in Ghana.” Pennsylvania State University: Department of Geography. October 11, 2006. Available at 

[3] Veiga, M.M., Baker, R. (2004). Protocols for Environmental and Health Assessment of Mercury Released by Artisanal and Small Scale Miners, Report to the Global Mercury Project: Removal of Barriers to Introduction of Cleaner Artisanal Gold Mining and Extraction Technologies.

[4] Veiga, M.M., et al. (2005). Pilot Project for the Reduction of Mercury Contamination Resulting From Artisanal Gold Mining Fields in the Manica District of Mozambique.

[5] 2 Veiga, M.M., et al. (2005). Pilot Project for the Reduction of Mercury Contamination Resulting From Artisanal Gold Mining Fields in the Manica District of Mozambique.

[6] 6 Timmins, Kerry J. “Artisanal Gold Mining without Mercury Pollution.” United Nations Industrial Development Organization. UNIDO. January 31, 2003. Available at

[7] 7 “Slum at the Summit.” Earth Report. Television Trust for the Environment. Accessed on September 15, 2008. Available at