Since 2001, with the rise in the price of gold, artisanal and small-scale gold mining (ASGM) has grown exponentially with 25-40 million people worldwide now working in the sector. It’s estimated that ASGM is now found in 80 countries, and is responsible for being the single largest release of mercury in the world. In 2015 ASGM emitted 675-1000 tonnes, which approximates 37.7% of the 2,200 tonnes of global mercury emissions.
Mercury is used in the gold mining process as an amalgam, attracting the gold found in the sediment like a magnet. Once the mercury is combined with the gold, it is burned off of the gold remnants, releasing the mercury as a toxic vapor that can be inhaled or absorbed into the ecosystem along with other toxic wastes used in the process.
Mercury release affects entire ecosystems and consequently the peoples that live there. Mercury is a fundamental element that cannot be broken down, and once released can stay in the environment for hundreds, if not thousands of years. Mercury is an extremely toxic substance that affects the brain, nervous system, kidneys, and lungs and can include symptoms such as lower IQ, sensory impairment, susceptibility to disease, disturbed sensation and a lack of coordination. In its various forms, mercury is particularly harmful to fetuses as an environmental toxin in pregnancy, as well as to infants and growing children who are still developing. Exposure to mercury can prevent nerve sheaths from forming properly by inhibiting the formation of myelin. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure.
Mercury is particularly dangerous when it is inhaled or makes it ways into lakes, waterways, and wetlands where it is converted by biogeochemical interactions into a highly toxic organic compound called methylmercury. Methylmercury is absorbed into the body almost six times more easily than inorganic mercury and can migrate through cells which normally form a barrier to toxins. Methylmercury magnifies through the food chain as predators eat other organisms and absorb the contaminants that their food sources contained. Over time through biomagnification, an individual who consumes plants or prey contaminated with methylmercury will acquire concentrations of mercury greater than in either their habitat or their food. As a result, top predators acquire greater body burdens of mercury than the fish they consume.
The toxicological effects of mercury are not only extremely dangerous to humans. Experts also suggest that mercury contamination affects populations of wildlife impacting reproduction, growth, neurodevelopment, and learning ability. In addition mercury also can cause behavioral changes which can lead to increased mortality and the risk of predation for some wildlife, compromising the survival of some affected populations and overall biodiversity.
Currently efforts are being made by governments and private groups to reduce and eradicate the use of mercury. On January 19, 2013, 140 countries ratified the the Minamata Convention on Mercury, an international treaty designed to protect human health and the environment from anthropogenic emissions and release of mercury and mercury compounds. It is expected that over the next few decades this international agreement will enhance the reduction of mercury pollution from targeted activities responsible for the major release of mercury to the immediate environment.
While progress is being made, mercury is still being released into the atmosphere at alarming rates. Educational groups, human rights organizations, governments and other NGO’s must take immediate action in regulating the release of mercury by promoting safer mercury free gold mining practices, and by educating populations on how to protect themselves and their ecosystem from the extreme consequences of mercury poisoning.
When the gold and mercury congeal into a solid, it is removed and the toxic mercury waste-water is poured back into the river
Mercury, bound to gold, is burned off into the atmosphere after its use leaving behind a gold nugget. Photo from Amazon Gold
Indigenous children are the most affected by mercury contamination in the Amazon.
Learn More about Mercury in the Amazon
Luis E. Fernandez is a research ecologist at the Carnegie Institution's Department of Global Ecology, and is the director of the Carnegie Amazon Mercury Project (CAMEP), a multi-institution research initiative that examines the impacts of artisanal gold mining,...