The researchers analyzed 428 samples of fish caught between 2017 and 2018 in five rivers in the Brazilian state of Amapá. The collection points were close to potential mining areas, where mercury is often used to separate gold from ore. The result: detectable levels of mercury were found in all samples. In 28.7% of them, the amount exceeded the WHO limit. The study — a joint effort by the Oswaldo Cruz Foundation (Fiocruz), WWF Brazil, the Amapá Institute for Scientific and Technological Research (IEPA) and the Institute for Indigenous Research and Training (Iepé) — reveals the risks to which the state’s Indigenous and riverine populations are exposed, especially children.
Iepé assistant executive director Décio Yokota, another co-author of the study, says fish from the area studied is consumed by people from at least four Indigenous territories: Wajãpi, Uaçá, Juminã and Galibi. For these populations, fish is the main source of protein and also the main vector of mercury contamination as a result of bioaccumulation. “Small fish eat the algae, then a bigger fish eats the small fish and is eaten by other, even bigger, fish,” he says. “That’s why the most contaminated fish are usually at the top of food chains. They accumulate a very large amount of mercury in the process.”
The proportion contaminated with unsafe levels of mercury was 20% among omnivorous fish, which feed on both fish and plants, and 2.4% among herbivorous fish. The study authors recommend eating a maximum of 200 grams (7 ounces) of carnivorous fish a week. In the case of mandubé (Ageneiosus inermis), pirapucu, tucunaré (Cichla monoculus) and trairão (Hoplias aimara), consumption should be restricted to once a month.
Source: Mongabay
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