março, 21 2022

Researchers analysed blood samples from 462 adults; 75.6% of them had results above the safety limit established by the WHO

By WWF-Brasil

A study carried out by LEpiMol (Laboratory of Molecular Epidemiology) of Ufopa (Federal University of Western Pará), in partnership with Fiocruz (Oswaldo Cruz Foundation) and WWF-Brazil, showed a high rate of mercury (Hg) concentration in the blood of residents of urban and riverside areas of the Low Tapajós River basin, in the State of Pará. The metal, which is used in mining areas to separate and extract gold, was found in all 462 research participants. Out of this total, 75.6% showed exposure above the safety limit of 10 µg/L established by the WHO (World Health Organization).

The results, which gather analyses of 203 individuals from the urban area of Santarém (Pará) and 259 participants from riverside communities, are described in an article published in the scientific journal “International Journal of Environmental Research and Public Health”.

“It is revolting how this is getting more and more serious and destructive for our lives”, comments Juci Bentes, environmental activist and member of the Tapajonic Youth Collective. “Mercury has been released into the riverbed and transformed into organic material, so it becomes part of the food chain, contaminating the fish that live in the river. Therefore, it is urgent to stop illegal mining activities in our region”, she highlights.

For the coordinator of the study, Professor Heloisa do Nascimento de Moura Meneses, from Ufopa, even though the mines are not close to the Lower Tapajós, the data show that the population is exposed to the effects of mercury contamination that currently occurs in the Amazon Basin. “Just like mining, deforestation and fires contribute to environmental contamination. We have a set of factors that affect the Tapajós River and, consequently, the people who live on its banks,” she explains.

For Raul Valle, Director of Social and Environmental Justice at WWF-Brazil, this kind of research should occur more frequently and in other places in the Amazon, so that we can have clarity on the dimension of the problem, which today is almost invisible.

“This can help to change the position of many congressmen in the region who are currently unconsciously supporting bills that will worsen this problem, such as bill 191/21, which intends to open up indigenous lands to mining companies and small-scale artisanal miners. It is not just indigenous communities that will be affected, but also people in large urban centres will be directly hit. It is not, therefore, a local problem, but a major regional problem".

Bill 191/20 was listed as a priority by the Bolsonaro government, which is now trying to approve the urgency to vote it hastily. It is part of a set of bills dubbed the “Destruction Package”, which also includes bills that encourage the theft of public lands (land grabbing), that weakens environmental licensing, and that makes it impossible to demarcate new indigenous lands, among others.

Main results

The study's fieldwork was carried out between 2015 and 2019, with blood collection for analysis of mercury levels in the laboratory. The adults over 18 years old who took part in the study were residents of 8 communities on the Tapajós River, a community on the Amazon River and the urban area of Santarém.
For the study coordinator, the data show that all people who have a frequent habit of consuming fish are at risk of exposure to mercury. “This is not just restricted to riverside areas, but also to urban areas,” she says.
Despite this, Heloisa do Nascimento explains that fish has great importance from a nutritional, economic, cultural and even touristic point of view, therefore, fish consumption should not be restricted.

“Environmental contamination by mercury is silent, colourless and odourless, but its effects can be long-term, including compromising the foetus, newborn and child and can be confused with other diseases”, explains the researcher.

According to the study, the prevalence of mercury exposure was higher in the riverine population (90%) than in those living in urban areas (57.1%). In the urban area, the mean mercury level was 33.6 ± 36.7 µg/L, while a level of 55.5 ± 65.7 µg/L was recorded in the riverside area. Comparing the riverine populations, the prevalence of mercury exposure on the banks of the Tapajós River (59.5%) was higher than that of the Amazon River (40.5%).
In summary, the high-exposure group (which exhibited levels above safe limits) had concentrations almost 4 times higher than the safe limit: 77.1% had blood Hg levels ranging between 10 and 50 µg/L; 11.2% between 51 and 100 µg/L; 6.9% between 101 and 200 µg/L, and 4.9% exhibited Hg levels ˃ 200 µg/L. Surprisingly, the highest level of Hg was 296.5 µg/mL, detected in a 47-year-old woman living in a riverside location, almost 30 times higher than the limit recommended by the WHO.

In the human body, high concentration of mercury can cause damage mainly to the central nervous system. Liver, kidneys, cardiovascular, gastrointestinal and immune systems can also be harmed.

The study also considered the age and sex variant. The 40-60 year old group exhibited relatively higher blood Hg concentrations than the 21-40 year old participants, with men having higher levels than women. The bioaccumulation of mercury associated with fish consumption may explain this variation.

In view of the results, Walter Kumaruara, who is a member of the Youth Council of Santarém (PA), says he is concerned about his parents, who live in one of the areas analysed in the research. “My father is a fisherman and they depend on fish for food. We also eat what comes from there. There’s no other way, it’s a matter of life,” he says.

Among the women sampled, 64.7% were of childbearing age (18 to 49 years), and of these, 69.9% had mean mercury levels of 36.2 µg/L. This raises concerns, given the increased risk of birth defects in newborns whose mothers were exposed to mercury during pregnancy. Methylmercury can cross the placenta and blood-brain barrier causing damage to the development of the central nervous system. Small amounts are enough to induce developmental problems in the foetus.

Fiocruz researcher Sandra Hacon recalls that mercury contamination from mining in the Amazon Basin, specifically in the Tapajós River, has been going on since the 1980s. According to her, the first studies published in the early 1990s by national and international institutions already indicated high levels of the metal in fish and in the indigenous populations. 

“The results of the current research carried out in riverine and urban population groups confirm the presence of mercury in the aquatic ecosystem and in the analysed groups, which represents a great environmental concern and, consequently, a serious public health problem, considering the neurotoxic property and the persistence and recycling capacity of mercury in the Amazon basin.”

About UFOPA

Created on November 5, 2009, through Law No. 12.085/2009, the Federal University of Western Pará (Ufopa) was the first Federal Institution of Higher Education located in the interior of the Brazilian Amazon, based in the city of Santarém, in the west of Pará state. It was born from the dismemberment of the Santarém campus of the Federal University of Pará (UFPA), and the decentralised unit of Tapajós of the Federal Rural University of the Amazon (UFRA), under the Support Program for Restructuring and Expansion Plans of Federal Universities. It is a multi-campus university and, in addition to its headquarters, it has campuses in the municipalities of Alenquer, Itaituba, Juruti, Monte Alegre, Óbidos and Oriximiná.

About Fiocruz

Created on May 25, 1900 - under the name of Federal Serum Therapy Institute -, Fiocruz was born with the mission of combating the major problems of Brazilian public health. Today, the institution, linked to the Ministry of Health, works to promote health and social development, generate and disseminate scientific and technological knowledge, and be an agent of citizenship.
Fiocruz continues to be guided by the production, dissemination and sharing of knowledge and technologies aimed at strengthening and consolidating the Brazilian Unified Health System (SUS) and contributing to the promotion of health and quality of life for the Brazilian population, to the reduction of social inequalities and for the national dynamics of innovation, with the defence of the right to health and broad citizenship as core values. More information at: fiocruz.br

About WWF-Brazil

WWF-Brazil is a Brazilian civil society organisation that for 25 years has been working collectively with partners from civil society, universities, governments and companies across the country to combat socio-environmental degradation and defend the lives of people and nature. We are connected in an interdependent network that seeks urgent solutions to the climate emergency. More information at: wwwf.org.br