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03.12.2024
Do you know how much mercury is in your body?
The widespread presence and persistence of mercury in the environment requires close health surveillance and reinforces the need for evidence-based solutions
Mercury is used to amalgamate gold, separating the precious metal from other sediments. The process is what makes gold mining possible, but it also has an impact on the ecosystem | Image: Shutterstock
When I ask people how much mercury there is in their body, they usually respond with a confused expression. It is not something most people ever think about. A common reaction is to ask, “…I haven’t been exposed, have I?”
However, news reports about communities exposed to this heavy metal, which is highly harmful to human health, are commonplace. This offers an indication of the great challenge faced by public health surveillance when it comes to environmental contamination.
At present, one in six deaths worldwide is caused by environmental pollution, a phenomenon that disproportionately affects the Global South, where around 90% of these deaths occur.
In Brazil, the issue of mercury in the environment is one of the best examples through which we can analyze the challenges of health surveillance.
Many Brazilians know that mercury is used in gold mining, but few know that it is also found in products consumed on a daily basis, such as cosmetics and certain fluorescent lamps.
Most people do not know, however, that even at room temperature, mercury continuously evaporates, and that it can remain in the air for decades, even traveling distances as far as from Brazil to the North Pole.
The problem of mercury in the environment, therefore, is not limited by distances or borders.
That was the guiding principle of the Minamata Convention on Mercury, an international treaty signed by 149 countries to date, which was internally adopted by Brazil in 2018 through Decree No. 9,470.
Before the COVID-19 pandemic, Brazil was among the five countries that contributed most to global mercury emissions.
The situation has worsened in recent years. Despite the pandemic, mining activity has exploded in the country, the result of a new “gold rush” that continues to this day.
On top this, wildfires and deforestation are at an all-time high, contributing to increased emissions by returning mercury stored in forest leaves to the air.
According to the European Environment Agency, there is already so much mercury in our environment that even if all human activities that release mercury were to be immediately stopped, it would take several centuries for significant levels of the mineral to return to the ground.
In addition to the omnipresence and permanence of the contaminant, another problem is the delay in the emergence of evident symptoms and how much the symptoms can vary.
From learning difficulties to hypertension, mercury causes a wide variety of effects and impacts.
In Brazil, it is mandatory to report confirmed or suspected cases of mercury poisoning, as is true of other diseases, such as COVID-19. Despite this fact, as of July 2023, only 668 cases had been officially registered nationwide in the 2007–2022 period.
Almost all Brazilian states have recorded cases of poisoning, demonstrating the ubiquity of human exposure to the metal. Just over 15% of cases occurred in the Amazon, which emits more than any other region of South America.
The state of Amapá has never reported any cases. However, the scientific literature points to a high prevalence of signs and symptoms of poisoning in the Amazonian population, illustrating serious underreporting in the region.
The situation is concerning, given the need for efficient, evidence-based allocation of resources.
Prevention and diagnosis
Understanding the omnipresent and long-lasting nature of mercury, the challenges of providing adequate health surveillance for the problem, and the importance of scientific evidence for planning and decision-making can help us to explain the limitations of simplistic or unrealistic solutions based on assumptions that do not consider the multiple layers of a complex reality.
When dealing with exposure to mercury or other forms of exogenous intoxication that affect vulnerable populations, it is essential to ensure that health professionals are properly trained and equipped to identify, diagnose, and report cases.
We urgently need to develop and validate diagnostic screening tools to help the work of health professionals, and to make these tools widely available for use among Brazil’s diverse populations and cultures.
Furthermore, since the brain is the organ targeted most by mercury and it has a very limited capacity for full recovery after damage, our biggest focus should also be on prevention, rather than just diagnosis.
In the Amazon, testing hair and urine for mercury should be frequent and routine.
To achieve this, investments need to be focused on improving local infrastructure, such as increasing the number of mercury analyzers and trained biomonitoring teams who reside permanently in the region.
This approach would allow us to understand the real situation and support evidence-based interventions.
Public initiatives
According to a systematic survey, research teams in the Brazilian Amazon with proven experience in human biomonitoring are primarily located at federal universities.
Strengthening these teams in the Amazon region would allow us to take advantage of the existing infrastructure and social reach of these public institutions without overburdening the health system.
These institutions also have a deep understanding of the Amazon region, which gives them the experience needed to implement local and culturally sensitive prevention strategies.
Initiatives such as the Amazonian Mercury Institute (IAMER), led by public universities in the Amazon with funding from the Brazilian Ministry of Justice and Public Security, are seen as investments with lasting impacts.
It is also important to note that the range of susceptibilities and vulnerabilities in different population groups in Brazil means that environmental monitoring of mercury in water, soil, air, plants, and animals is insufficient as a preventive strategy.
For example, recent data showed that piscivorous fish (those that feed on other fish) sold at Amazonian markets contain average mercury levels of 0.603 parts per million (ppm), considered suitable for human consumption according to Brazilian legislation (which allows up to 1 ppm of mercury in piscivorous fish).
However, this means that a single 200-gram portion of piscivorous fish, such as wolf fish or rhamdia, may be enough to exceed the maximum weekly mercury intake recommended by the World Health Organization (WHO).
Unfortunately, Brazilian legislation disregards the culture and dietary habits of traditional Amazonian communities (Indigenous, riverside, and quilombola peoples) who often consume fish on a daily basis.
Many of these traditional communities maintain a close connection with the surrounding environment, making them the first to suffer the impacts of environmental pollution.
The Brazilian government desperately needs to establish guidelines on maximum mercury consumption and body burden, which would help monitor human exposure and prevent intoxication.
These recommendations, combined with the routine use of standardized forms to assess food consumption, could serve as a strategy for early detection among individuals at risk.
Brazil could also make better use of community health agents and Indigenous health agents, who work with vulnerable populations, to adapt these recommendations to the cultural practices of local communities, improving adherence and facilitating early identification of high-risk individuals.
If you want to see these recommendations become reality and you want to know how much mercury is in your body, you can start by supporting Bill No. 1,011/2023, which is currently being processed in the Senate and would institute a national policy for the prevention of exposure to mercury.
Maria Elena Crespo López is a professor at the Federal University of Pará (UFPA) – Molecular Pharmacology Laboratory -, head of the Amazon Mercury Institute (IAMER), and a member of the United Nations Environment Programme’s Global Mercury Partnership.
Opinion articles do not necessarily reflect the views of Science Arena or Hospital Israelita Albert Einstein.
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