Health Risk Assessment Attributed to Consumption of Fish Contaminated with Mercury in the Rio Branco Basin, Roraima, Amazon, Brazil

Abstract

The aim of this study was to assess the health risk attributable to the consumption of mercury-contaminated fish for the urban and non-urban populations living in the Roraima state, Amazon, Brazil. Seventy-five fish specimens distributed across twenty different species, comprising four trophic levels (i.e., herbivore, omnivore, detritivore, and carnivore), were collected at four locations in the Branco River Basin. The fish samples were sent to the Toxicology Laboratory at Evandro Chagas Institute to determine the total-Hg levels by using the cold vapor atomic system (CVAAS). The total-Hg levels ranged from 0 to 3.159 µg/g. The average concentration in non-carnivorous species (n = 32) was 0.116 µg/g, and among carnivorous fish (n = 43), it was 0.869 µg/g. The weighted average of contamination levels for all samples was 0.545 µg/g. The health risk assessment was conducted according to the methodology proposed by the World Health Organization and different scenarios of human exposure were considered, based on three levels of fish consumption (low: 50 g/day; moderate: 100 g/day and high: 200 g/day). Women of childbearing age ingest 5 to 21 times more mercury than the dose considered safe by the U.S. EPA and intake a dose from 2 to 9 times higher than the safe dose proposed by FAO/WHO. Children under 5 years of age ingest from 18 to 75 times the dose proposed by the U.S. EPA and from 8 to 32 more mercury than the limit proposed by FAO/WHO. In summary, regardless of the level of fish consumption, type of residency (urban or non-urban), and the subset of the population analyzed, anyone who consumes fish from the locations sampled is at high risk attributable to mercury ingestion, with the only exception of adult men, who consume an average of 50 g of fish per day.

Long-Term Environmental Methylmercury Exposure Is Associated with Peripheral Neuropathy and Cognitive Impairment among an Amazon Indigenous Population

“…All these studies revealed that the average Hg levels, assessed by biological exposure markers, were above the limits recommended by several international health agencies (e.g., FAO/WHO, U.S.EPA, NRC, Health Canada), as a result of the artisanal gold mining as the main exposure source [22][23][24]. Furthermore, a recent study published by Vasconcellos et al (2022) reinforces these findings, once it pointed to high Hg concentrations in fish collected from rivers that cross the Yanomami Indigenous Land, in the state of Roraima, Brazil [25]. Fish such as Filhote/Piraíba, Piracatinga, Pirandirá, and Barba-chata, which are much appreciated by residents of this region, had total Hg levels above 1.0 µg/g and therefore pose a high health risk [25].…”

Clinical, Laboratory and Neurodevelopmental Findings in Children from the Yanomami-Ninam Population Chronically Exposed to Methylmercury

“…MeHg is absorbed by animals, and as they move up the food chain, its concentration increases. Populations that have a diet based on fish, such as the indigenous people of the Amazon, are particularly vulnerable to methylmercury contamination [ 7 , 8 ]. A study carried out between 1994 and 1995, in a section of the Yanomami Territory affected by mining activity, found mercury levels in fish and indigenous people that exceeded the limits established by the World Health Organization (WHO) as safe [ 9 ].…”

Risk Assessment of Mercury-Contaminated Fish Consumption in the Brazilian Amazon: An Ecological Study

“…Over time, metallic mercury used in gold mining accumulates in river sediments, where it is converted into methylmercury (the most dangerous chemical form to human health and the ecosystem) and is quickly incorporated into the organisms that make up the aquatic biota [ 3 , 4 , 5 , 6 ]. Much of the danger associated with methylmercury is due to its high neurotoxic potential and its ability to bioaccumulate and biomagnify in aquatic food chains.…”

“…In recent years, evidence of increased mercury contamination in fish in the rivers that form the Amazon basin has significantly increased due to the growth of mining activity. This has raised a series of concerns about the health of the population living in the region [ 6 , 17 , 18 ].…”