Amazon fish contaminated with excessive mercury levels

Researchers call for urgent action to eliminate local illegal mining

Published on 04/06/2023 - 14:30 By Paula Laboissière - Agência Brasil - Brasília

A study led by the Oswaldo Cruz Foundation (Fiocruz) reveals that fish from all six Amazonian states exceed the acceptable limit for mercury contamination (greater than or equal to 0.5 micrograms per gram) established by the World Health Organization (WHO).

Conducted in collaboration with Greenpeace Brazil, the Indigenous Research and Training Institute (Iepé), the Socio-environmental Institute, and the World Wildlife Fund (WWF-Brazil), the study highlights that the highest contamination rates are found in Roraima, where 40 percent of fish exceed the recommended limit, and Acre, with an index of 35.9 percent. The lowest rates were observed in Pará (15.8%) and Amapá (11.4%).

"On average, 21.3 percent of the fish available in local markets and consumed by families in the Amazon region exceed safe mercury limits," announced Fiocruz in a statement, emphasizing that all population groups analyzed surpassed the recommended reference dose for daily mercury intake.

In the most critical municipality, Rio Branco, the capital of Acre, the potential mercury intake exceeded the U.S. government's Environmental Protection Agency's reference dose by 6.9 to 31.5 times.

Fiocruz warned, "Women of childbearing age - the most vulnerable group to mercury's effects - are ingesting up to nine times the recommended dose, while children between 2 and 4 years old are ingesting up to 31 times more mercury than recommended."


According to Fiocruz, the study evaluated the health risks associated with consuming contaminated fish by visiting markets and fairs in 17 Amazonian municipalities, where samples were purchased. The survey took place from March 2021 to September 2022 in the states of Acre, Amapá, Amazonas, Pará, Rondônia, and Roraima.

A total of 1,010 fish samples from 80 different species were analyzed, obtained from markets, fairs, and directly from fishermen, representing the daily consumption patterns of local consumers. Of the samples, 110 were herbivorous fish (that consume plant foods), 130 were detritivorous (that consume organic detritus), 286 were omnivorous (that consume both animal and plant foods), and 484 were carnivorous (that consume animal foods).

Carnivorous fish, which are more popular among consumers, exhibited higher contamination levels compared to non-carnivorous species. The comparative analysis revealed that carnivorous fish have contamination levels 14 times higher than non-carnivorous fish.

"The researchers' main recommendation is to exercise greater control over the Amazon territory and eliminate illegal mining and other sources of mercury emissions into the environment," concluded Fiocruz.

Translation: Mário Nunes -  Edition: Denise Griesinger

Latest news