Amazon has more than 4,000 illegal mining sites, shows ACTO study with WWF-Brazil

agosto, 22 2023

The subject was addressed in the final declaration of the Amazon Summit
By WWF-Brazil and ACTO

A survey produced by WWF-Brazil at the request of the Amazon Cooperation Treaty Organisation (ACTO) points out that 4,114 illegal mining sites plague the Amazon. The issue is historic and affects all countries in the Amazon basin. Since 1994, around 2,300 tons of mercury have been dumped in the Brazilian Amazon. However, this number, which was already high, has been growing more and more: today, according to a series of studies analysed, it is believed that 150 tons of mercury are being dumped per year in the region.

Riverside and indigenous populations are the most affected by mercury. They present levels of contamination higher than those established by the World Health Organisation. In Brazil and Ecuador, riverside communities are the most affected, with average concentrations of 15.43 and 12.3 (ppm), respectively. In Peru and Colombia, the greatest attention should be given to indigenous communities, which have average metal concentrations of 27.75 and 23.01 (ppm), respectively.

According to the technical note, among the countries that are part of the biome, Brazil has the highest values of mercury concentration found in different species of fish: they are 8.71 (ppm), followed by French Guiana with 6.45 (ppm) and Suriname with 4.62 (ppm). This year as well, a study found that fish from six states in the Brazilian Amazon had levels of contamination above the acceptable limit.

“The use of mercury has a great impact both on the health of those who work in the mines, as well as thousands of people who consume fish frequently. Mercury is a heavy metal of a cumulative nature, that is, it is concentrated throughout the food chain. This reality needs to be addressed in a joint plan of the many Amazonian countries, says Mauro Ruffino, coordinator of ACTO's Regional Amazonian Observatory (ORA).

The effects of mercury are harmful and often irreversible. It affects the nervous system, digestive tract, immune system, lungs and kidneys, it also causes damage to the formation of babies that can be harmed with brain damage such as motor paralysis and hearing and vision problems. “In addition to the impact it causes on the environment, mercury also affects public health - and this is a problem that is still underreported, which urgently requires an action plan to take care of the affected people”, says Raul do Valle, specialist in Public Policies at WWF-Brazil.

The data indicated in the technical note were gathered by the Mercury Observatory, the largest initiative for compiling and georeferencing environmental information and mercury contamination in humans and fish in the Amazon region. The database comprises 139 studies, from the years 1990 to 2022, for contamination levels in human populations, and 94 studies, from 1992 to 2022, for contamination levels in fish.

The analysis of available studies shows that there is a disparity in scientific production on the subject between countries. Brazil has the most published studies (61 studies or about 66%), followed by Peru (13 studies or 9.5%) and Colombia (11 studies, representing 8%). It is important to stress that these disparities in the number of studies can also reflect on the results found, since the registered studies are concentrated in the main rivers of the Amazon region and there are still large voids, especially in the Andean and northern regions of the biome.


The authors point out that reducing and mitigating the impacts of mercury contamination in the Amazon is a complex challenge. It involves quantifying the amount of mercury released in each country and its transport to neighbouring countries, assuming a serious political commitment to reducing mercury emissions through anthropic actions, such as deforestation, construction and operation of hydroelectric plants, changes in land use and illegal and irregular gold mining. Therefore, they list three main actions:
  • To control the gold production chain and its effects on environmental mercury emissions;
  • To identify and measure mercury pollution events, with characterization of associated risks;
  • To develop and implement measures in order to reduce the risks and impacts of mercury contamination in exposed and vulnerable human populations and wild species.

About the Amazon Cooperation Treaty Organisation (ACTO)

ACTO is an intergovernmental organisation, formed by eight Amazonian countries: Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela, which signed the Amazon Cooperation Treaty (ACT), becoming the only socio-environmental bloc in Latin America. ACTO, with a broad vision of the South-South Cooperation process, works in different dimensions: political-diplomatic, strategic and technical, creating synergies between governments, multilateral organisations, cooperation agencies, organised civil society, social movements, scientific community, productive sectors and society as a whole, within the scope of the implementation of the ACT.

About WWF-Brazil

WWF-Brazil is a Brazilian NGO that has been working collectively for 26 years with partners from civil society, universities, governments and companies across the country to combat socio-environmental degradation and defend people's lives and nature. We are connected in an interdependent network that seeks urgent solutions to the climate emergency.
Vista aérea do Garimpo Juruena, no Mato Grosso
Riverside and indigenous populations are the most affected by mercury
© Zig Koch / WWF