Artisanal and Small-Scale Gold Mining (ASGM) in developing countries is the largest remaining intentional use of mercury in the world. In contrast to other industrial uses, all of the mercury used in ASGM is released directly into the environment. As a result, worldwide ASGM is second only to the burning of coal (primarily in coal-fired power plants) as a source of mercury to the atmosphere. Mercury use in ASGM is estimated to be 1608 tonnes per year in 2013 (GMA 2013).
Mercury is a naturally occurring element that is highly toxic. Mercury vapour causes damages to the nervous system, kidneys, causes insomnia, tremors, depression, and gum disease. Once released into the atmosphere, mercury can travel long distances, polluting lakes and streams. As a result of human activities, mercury levels in many fish species around the world have risen to the point of being unsafe for those who rely on fish as a regular part of their diet. Its most toxic form – methylmercury – accumulates in large predatory fish and is taken up in our bodies through eating fish, with the worst impacts on babies in utero and small children. Mercury inhalation is threatening to small children, child in utero, pregnant women, women of childbearing age. It is passed on from the mother to the child and fetuses. Children are most susceptible to developmental effects from mercury exposure.
Mercury is used in ASGM to concentrate gold by forming a mercury-gold amalgam. Heating the amalgam then evaporates the mercury leaving only the gold. During the heating of the amalgam, mercury vapour is released, directly exposing miners and their communities. In addition, the disposal of contaminated tailings results in the release of mercury into local soil and waterways, where it can remain for centuries.
Other problems associated with the ASGM sector include silica dust exposure, child labour, prostitution, criminal activity, lack of transparency in supply chains, and the fact that small-scale miners are at the end of long and complex supply chains.
