New study shows daily mercury intake exceeds safe limits in six Amazonian states

2023-05-30 13:50:00

According to an unprecedented study, the use of mercury in mining areas in states in the Amazon causes high levels of contamination in fish|Daniel Marenco

a new study carried out in the main urban centers of the Amazon, covering six states and 17 municipalities, reveals that fish in the region are contaminated by mercury. The results show that fish from all six Amazonian states had contamination levels above the acceptable limit of ≥ 0.5 µg/g, established by the World Health Organization (WHO).

The worst rates are in Roraima, with 40% of fish with mercury above the recommended limit, and Acre, with 35.9%. The lowest indicators are in Pará, with 15.8%, and in Amapá, with 11.4%. On average, 21.3% of the fish sold in the localities and that reach families’ tables in the Amazon region have mercury levels above safe limits.

In all population strata analyzed, daily mercury intake exceeded the recommended reference dose. In the most critical municipality, Rio Branco (AC), the potential intake of mercury exceeded 6.9 to 31.5 times the reference dose indicated by the Environmental Protection Agency of the US government (EPA), 0.1 μg /kg pc/day. Women of childbearing age – the public most vulnerable to the effects of mercury – would be ingesting up to nine times more mercury than the recommended dose; while children aged two to four years up to 31 times more than advised.

In Roraima, the second most critical state, the potential intake of mercury extrapolated from 5.9 to 27.2 times the reference dose. Considering the population strata most vulnerable to contamination, women of childbearing age would be ingesting up to eight times more mercury than the indicated dose, and children aged two to four years up to 27 times more than the recommended amount.

This information is from a study carried out by researchers from the Sérgio Arouca National School of Public Health of the Oswaldo Cruz Foundation (Ensp/Fiocruz), the Federal University of Western Pará (UFOPA), Greenpeace Brasil, Iepé, Instituto Socioambiental (ISA) and WWF-Brasil. The survey sought to assess the risk to human health due to the consumption of contaminated fish – and, for that, it visited markets and fairs in 17 Amazonian cities where the samples used in this research were purchased.

“This is the first study that evaluates the main Amazonian urban centers spread across six states. He reinforces an alert for an issue that is already known, but not resolved, which is the risk to food security in the Amazon region generated by the use of mercury in prospecting activities. It is worrying that the main source of protein in the territory, if ingested without control, causes damage to health because it is contaminated”, emphasizes Decio Yokota, coordinator of Iepé’s Information Management Program.

“We are facing a public health problem. We know that contamination is more serious for pregnant women, as the fetus can suffer neurological disorders, damage to the kidneys and the cardiovascular system. Children, on the other hand, may have motor and cognitive difficulties, including problems with speech and the learning process. In general, the effects are dangerous, often irreversible, the symptoms may appear after months or years of exposure. It is urgent to create public policies to assist people already affected by mercury contamination and preventive measures, to control its use”, warns Dr. Paulo Basta, researcher at Fiocruz’s National School of Public Health.

O lifting was held from March 2021 to September 2022 in the states of Acre, Amapá, Amazonas, Pará, Rondônia and Roraima. Samples were collected in the municipalities of Altamira (PA), Belém (PA), Boa Vista (RR), Humaitá (AM), Itaituba (PA), Macapá (AP), Manaus (AM), Maraã (AM), Oiapoque ( AP), Oriximiná (PA), Porto Velho (RO), Rio Branco (AC), Santa Isabel do Rio Negro (AM), Santarém (PA), São Félix do Xingu (PA), São Gabriel da Cachoeira (AM) and Tefe (AM). 1,010 specimens of fish of 80 different species, purchased at markets, fairs and directly from fishermen, were evaluated, simulating the daily lives of local consumers.

Of the overall sample, 110 were herbivores, 130 detritivores, 286 omnivores and 484 carnivores. Carnivores, more appreciated by final consumers, showed higher levels of contamination than non-carnivorous species. The comparative analysis between species indicated that contamination is 14 times higher in carnivorous fish when compared to non-carnivorous ones. Therefore, the study makes an indication of consumption for the main species of fish sampled, considering the level of contamination and the location.

The main recommendation that the researchers make is to have greater control of the Amazonian territory and to eradicate illegal mining and other sources that emit mercury into the environment. “In addition to environmental degradation, illegal mining brings a trail of destruction that includes trafficking in drugs, weapons and wild animals, in addition to sexual exploitation. Therefore, the State needs to guarantee greater control and security for local populations. However, other actions such as monitoring deforestation and burning also reduce exposure to mercury, as they impact the dynamics of soils and rivers and streams,” says Marcelo Oliveira, conservation specialist at WWF-Brasil.

Read too:
Illegal mining contaminates fish in rivers in Roraima, reveals study
ISA study proves that mining impedes social progress in the Amazon

about the study

Fish samples were collected in 17 Amazonian municipalities, totaling six sampled states. The fish were purchased in public markets, open-air markets or from fishermen at fishing landing points, from March 2021 to September 2022. Whenever possible, at least three different species were sampled in each trophic guild (carnivore, omnivore, detritivore and herbivore) and at least three individuals of each species, with different sizes.

The detection of Hg levels was performed by atomic absorption spectrometry in the laboratories of the Mineral Technology Center (CETEM) and the Evandro Chagas Institute (IEC). The health risk assessment study attributed to the consumption of contaminated fish was calculated according to EPA parameters. For this, four population strata were considered: women of childbearing age (10 to 49 years old); adult males (≥ 18 years); children from 5 to 12 years old; and children aged 2 to 4 years.

The estimate of fish consumption per person was based on the report on fish consumption in the Amazon region of Brazil, with an average per capita of 100 grams of fish per day in urban environments. The calculation of the risk ratio (RR) was also evaluated, which indicates the potential for damage to health caused by the consumption of contaminated fish and the health risk assessment.

Authors: Ciro Campos, Paulo Cesar Basta, Ana Claudia Santiago de Vasconcellos, Gustavo Hallwass, Decio Yokota, Danicley Saraiva de Aguiar, Daniel de Oliveira d’El Rei Pinto and Marcelo Oliveira da Costa

Check out the full study here

More information

Press Office Greenpeace Brazil

[e-mail] | [phone]

AViV Comunicação – Press Office WWF-Brasil

Rita Silva – [e-mail] | Sandra Miyashiro – [e-mail]

IEPÉ – Indigenous Research and Training Institute

[e-mail] | 11 984 002 482

ISA – Socio-Environmental Institute

[e-mail] | 95 991282659