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

Abstract

Mercury is one of the most dangerous contaminants on the planet. In recent years, evidence of mercury contamination in the Amazon has significantly increased, notably due to gold-mining activities. Although mercury contamination in fish has consistently been documented, little is known about the risk associated with fish consumption by populations in urban areas of the Amazon. We sampled 1010 fish sold in public markets in six state capitals and 11 additional cities. Mercury levels were determined for each specimen, and the evaluation of the health risks associated with consuming mercury-contaminated fish was conducted according to the methodology proposed by the World Health Organization (WHO). Our study reveals that more than one-fifth (21.3%) of the fish sold in urban centers had mercury levels above the safe limits (≥0.5 µg/g) established by the Brazilian Health Surveillance Agency (ANVISA). The prevalence of Hg contamination ≥0.5 µg/g was approximately 14 times higher in carnivorous than in noncarnivorous fish. The analysis of the risk attributable to fish consumption reveals that daily mercury intake exceeded the reference dose recommended by the U.S. EPA in all population groups analyzed, reaching up to 7 and 31 times in women of childbearing age and children from 2 to 4 years old, respectively. However, these risks are diverse depending on the type of fish consumed and must be considered to formulate appropriate nutritional guidelines for safe fish consumption by the local community.

Trends in Mercury Contamination Distribution among Human and Animal Populations in the Amazon Region

“…The Madeira River and its floodplains serve as significant boundaries in the geographic zoning of the ecoregions considered in this study. The results related to animals were predominantly from aquatic ecosystems and were assessed within the context of the fish food web and bioconcentration of Hg, considering the differences between pelagic and demersal species and their distinct feeding groups in these tropical zones (feeding guilds) [ 41 , 77 ].…”

“…Also, the few studies reporting the exposure of humans to Hg have largely failed to include Amazonian territories outside of Brazil [ 39 ]. Scientometric studies on Hg contamination have revealed a more pronounced focus on the Amazon compared to other Brazilian biomes, emphasizing gold mining, fish exposure to Hg, and contamination by Hg in water bodies and river sediments [ 40 , 41 ]. Additionally, a recent systematic review of the geological characteristics of the Amazon basin highlighted the uneven distribution of dangerous metal enrichment, including mercury, owing to mining activities, as well as a scarcity of data from other countries in the Amazon basin [ 42 ].…”

Mercury in Fish and Human Hair and Estimated Dietary Intake in a Riverside Community of the Madeira River Basin in the Brazilian Amazon

“…Considering that the participants in our study consumed fish two to six times a week ( Table 1 ), we divided the PTWI value by seven to obtain the recommended daily limit (PTWI/7 = 0.23 μg kg −1 day −1 ). In addition, the risk ratio (RR) was also used to estimate the risk to human health, where EDI Abs is the fraction of Hg absorbed by the human body through fish consumption (80% of EDI) and RfD represents the daily oral chronic reference dose of MeHg (0.1 μg kg −1 ) [ 69 ] (Equation (2)) [ 27 ]. RR values greater than or equal to one indicate that the dose of MeHg absorbed by a test subject is higher than the reference dose.…”

“…In the Amazon, fish consumption is the main source of protein and the main route of exposure to MeHg in riverside populations [ 21 , 22 , 23 ], often exceeding the safe limits established by regulatory agencies [ 24 , 25 , 26 , 27 ]. In humans, approximately 15% of Hg 2+ is absorbed from the gastrointestinal tract and accumulated in the liver and kidneys, while the majority is excreted through feces and urine [ 28 , 29 ].…”

Trends in Mercury Contamination Distribution among Human and Animal Populations in the Amazon

“…Also, the few studies reporting the human exposure of humans to Hg have largely failed to include Amazonian territories outside of Brazil [41]. Scientometric studies on Hg contamination have revealed a more pronounced focus on the Amazon compared to other Brazilian biomes, emphasizing gold mining, fish exposure to Hg, and contamination by Hg in water bodies and river sediments [42,43]. Additionally, a recent systematic review of the geological characteristics of the Amazon basin highlighted the uneven distribution of dangerous metal enrichment, including mercury, owing to mining activities, as well as a scarcity of data from other countries in the Amazon basin [44].…”