The health risks caused by the use of mercury in mining

In mining, mercury is usually used for gold separation

Bruna Alves

From São Paulo to BBC News Brazil

Illegal mines, which use excess mercury to enable the separation of gold from other sediments, cause the contamination of fish, the death of rivers, the removal of vegetation cover and, consequently, the escape of animals.

All this is reflected, according to experts, in misery and various diseases that plague populations of the affected regions.

This is what has happened to the inhabitants of the Yanomami Indigenous Land, which is between the states of Roraima and Amazonas.

The situation of public calamity and neglect that afflicts these people gained worldwide prominence earlier this year when it was revealed after a trip by federal government authorities.

Images of women and children in extreme malnutrition and devastated by diseases such as malaria and tungiasis (popularly known as ‘far-upe’) gained prominence.

When methylmercury and mercury vapor enter the body, through the consumption of contaminated fish or breathing mercury vapor, it affects the functioning of the nervous system and the brain, according to experts. Effects may include weakness, difficulty studying, tiredness, difficulty getting around, problems with vision and hearing. Understand the following.

Mercury on indigenous lands

Mercury is a metal that is part of the Earth’s constitution — a natural element found in rivers, soil, water and even in the air.

Its use in industry is allowed – and even in gold mines, as long as it is authorized by the National Mining Agency (ANM).

“It is a legalized compound, regulated and monitored by the Brazilian Institute of the Environment and Renewable Natural Resources (Ibama) and the other competent bodies,” explains Ana Claudia Santiago de Vasconcellos, PhD in public health and researcher at the Joaquim Venâncio Polytechnic School of Health, of the Oswaldo Cruz Foundation (EPSJV/Fiocruz).

In general, the concentrations of mercury in nature are low.

However, in some activities, the use of higher amounts of the substance may pose problems.

In addition, mercury has been used for decades by prospectors for gold extraction in indigenous lands.

“What we are seeing in the Yanomami indigenous lands is illegal, because the Federal Constitution says that there can be no gold mining, with mercury or without mercury, on indigenous land or in any environmental conservation unit,” says Vasconcellos, who is also the coordinator of research projects in the area of indigenous health, a specialist in human exposure to chemical contaminants and the impact of gold mining

In practice, according to her, these mines are installed without regulation and there is no environmental agency that actively monitors the use of mercury – responsible for a series of sanitary, environmental, sociocultural and economic impacts on communities.

How does mercury reach the population?

In the case of extraction in the rivers of the Amazon, for example, gold is in the environment in the form of very small particles.

Metallic mercury, in this case, is used to unite them, forming an amalgam (metallic alloy) with gold, enabling their separation from other components. But for this to happen, there is a chemical change.

When mercury reaches rivers, it turns into methylmercury, a highly toxic contaminant, whose pollutants end up disseminated in high quantities, which spread rapidly through the current.

In illegal mining, mercury also contaminates the atmosphere, since to separate the gold, it is common for the amalgam to be burned without using an environmental control system. With heat, the metal becomes vapor and spreads through the air. Therefore, mercury is a global pollutant.

All these activities that use mercury as a by-product become a danger to living beings, especially to fish, which incorporate this toxic substance and transmit it to humans, as some studies have already pointed out.

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The so-called metallic mercury used in illegal mines, in contact with water, for example, undergoes chemical transformations and turns into methylmercury, a highly toxic substance

Many wild animals also flee the region to escape the mining activity. Others die or are hunted by the prospectors, leaving the indigenous population with nothing to put on the table.

To get an idea of the problem, a study conducted by Fiocruz, in 2019, in the Yanomami indigenous population, found the presence of mercury in 56% of women and children in the Maturacá region, in the Amazon.

The 272 hair samples analyzed exceeded the limit of 2 micrograms of mercury per gram of hair tolerated by the World Health Organization (WHO).

Another work coordinated by Fiocruz in partnership with the Instituto Socioambiental (ISA), also carried out in the Yanomami reserve (RR), showed that, in some indigenous villages, 92% of people were contaminated by mercury.

The index, considered very high by experts, is a direct result of environmental contamination caused by thousands of illegal mines that exploit the soil in search of gold in that region, using mercury as a base. Other peoples are also affected, according to experts.

Fiocruz did a new research in the last quarter of 2022 to be published in March, and the results indicate that, in the region where a subgroup of Yanomami lives, the problem continues: rivers committed to excess mercury, highly turbid waters and low availability of fish, essential food for the people.

After several warnings made to the Brazilian government about the serious humanitarian situation faced by the Yanomami indigenous people living in communities in northern Brazil, “the measures taken were clearly insufficient”, according to the representative in South America of the Office of the United Nations High Commissioner for Human Rights (OHCHR), Jan Jarab.

What are the health risks of mercury?

Health agencies differ somewhat from the recommendation of mercurial doses considered “acceptable” so as not to cause health risks. The EPA, the North American environmental protection agency, for example, recommends a maximum intake dose of 0.1 micrograms of mercury per body kilogram/day.

The World Health Organization (WHO) indicates that the limit of intake of foods that have this component is a maximum of 0.23 micrograms per body weight/day, for women and children, and 0.45 for adult men.

“The peoples of the Amazon ingest ten times more than this limit,” says Vasconcellos, from Fiocruz.

In general, when the intake of the metal is considered excessive, the health risks are several.

“Methylmercury has a specific target, which is the central nervous system. So, when we eat a contaminated fish, the mercury is absorbed, falls into the bloodstream and reaches the brain, where it can impair hearing, motor coordination, intelligence, in addition to causing the development of problems such as depression and insomnia,” warn Vasconcellos.

According to experts, these brain lesions caused by contamination are irreversible. However, when an adult is exposed to methylmercury, the damage is usually smaller and more spaced. This means that, in an adult brain, the symptoms can be more subtle throughout life.

Pregnant women and babies

The excess of this compound in the body can also generate heart problems and is extremely dangerous for pregnant women, since in addition to being contaminated, the fetus is also affected.

“And he is much more vulnerable to the effects of methylmercury than the adult brain. Therefore, it is believed that some children are born with serious cognitive problems,” says the researcher.

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The extraction of gold in indigenous lands and environmental reserves is prohibited, so in these cases, all forms of mining is illegal

“They are children who have learning difficulties, they take a long time to learn to speak, sit,” highlights the coordinator of research projects in the area of indigenous health, saying that complaints have already been made of children who are being born with cerebral palsy in some regions of the Amazon, precisely due to exposure to methylmercury.

“This is a strong suspicion, but we are not absolutely sure. The fact is that cerebral palsy has increased at the same rate as the expansions of illegal mines”.

“People living in the Amazon are chronically exposed to low doses of mercury, but daily for life. It is different from an acute exposure, for example, that affects the worker of a factory,” explains the Fiocruz researcher.

How to reduce mercury contamination?

Vasconcellos says that “the solution is to end the mining activity, especially in indigenous lands and in conservation units”.

The estimate is that it will take 100 years for the metal disseminated in the environment to be eliminated, taking into account that they are pollutants of high persistence.

There is the possibility of prospectors, as well as large miners, using cyanide instead of mercury, but it is also harmful to health. And the form of gold exploited by legalized companies is different from legal and illegal mines.

For Zuleica Castilhos, PhD in environmental geochemistry, post-doctorate in public health from Fiocruz, researcher at the Mineral Technology Center, of the Ministry of Science, Technology and Innovation (CETEM/MCTI), a “clean” mining goes far beyond the replacement of mercury in the processes.

“A mine, to be called clean, needs to observe many other things, such as respect for human rights, labor rights, the gender issue. And we are far from getting there, even in legality, let alone in illegality,” says the expert, who is also the leader of the research group “Ecosystemic Assessment of Environmental Risks and Human Health in Territories with Mining”, in addition to being responsible for the Laboratory of Environmental Mercury Speciation.

Even so, according to Castilhos, it would be possible to improve the mines in terms of technology that would replace mercury.

“But, in this case, we are not talking about an adequate mining, but a replacement, forgetting all the other aspects,” says the expert, who coordinated, in 2018, the survey “National Inventory of Emissions and Releases of Mercury in the Scope of Artisanal Mining and Small Gold Scale in Brazil”, whose general objective was to estimate the quantities of mercury emitted into the atmosphere and released into

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Experts argue that the blame for the tragedy that plagues the Yanomami people, among others, is not of the hardworking prospector, but of the great businessmen who are behind the gold trade obtained through illegal mines

The researcher believes that, in Brazil, there is currently no substance in mining that replaces mercury in terms of ease, agility and, especially, cost-benefit.

According to her, in several countries, including Brazil, research is being carried out with vegetables (plant extracts, such as the balsa stick found in the Amazon Forest), but the process is still in the experimental phase.

Some mines work in a legalized way, outside the indigenous lands, and try to improve the use of mercury, but, according to the researcher, in many cases there is a lack of adequate training of professionals.

“And often, not even people know that those levels are increased. When we went to the field and did these surveys in real time, we were amazed by the high values of mercury in the atmosphere, and people were even using environmental protection equipment, but it’s no use, if [the processes] are not well done,” argues Castilhos.

One of the obstacles encountered to solve the problem is the underreporting of cases of mercury poisoning, according to experts, who advocate an effective intoxication notification system as a priority.

“These data should be incorporated into an information system. But that doesn’t happen, and it’s bad, because it takes away the visibility of the problem. Imagine if covid cases were not notified. Would we have a vaccine?” asks Vasconcellos.

For the specialist, an effective public policy needs to be developed, the solution of which is far from immediate.

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