Abstract
The Amazonian indigenous peoples depend on natural resources to live, but human activities’ growing impacts threaten their health and livelihoods. Our objectives were to present the principal results of an integrated and multidisciplinary analysis of the health parameters and assess the mercury (Hg) exposure levels in indigenous populations in the Brazilian Amazon. We carried out a cross-sectional study based on a census of three Munduruku indigenous villages (Sawré Muybu, Poxo Muybu, and Sawré Aboy), located in the Sawré Muybu Indigenous Land, between 29 October and 9 November 2019. The investigation included: (i) sociodemographic characterization of the participants; (ii) health assessment; (iii) genetic polymorphism analysis; (iv) hair mercury determination; and (v) fish mercury determination. We used the logistic regression model with conditional Prevalence Ratio (PR), with the respective 95% confidence intervals (CI95%) to explore factors associated with mercury exposure levels ≥6.0 µg/g. A total of 200 participants were interviewed. Mercury levels (197 hair samples) ranged from 1.4 to 23.9 μg/g, with significant differences between the villages (Kruskal–Wallis test: 19.9; p-value < 0.001). On average, the general prevalence of Hg exposure ≥ 6.0 µg/g was 57.9%. For participants ≥12 years old, the Hg exposure ≥6.0 µg/g showed associated with no regular income (PR: 1.3; CI95%: 1.0–1.8), high blood pressure (PR: 1.6; CI95%: 1.3–2.1) and was more prominent in Sawré Aboy village (PR: 1.8; CI95%: 1.3–2.3). For women of childbearing age, the Hg exposure ≥6.0 µg/g was associated with high blood pressure (PR: 1.9; CI95%: 1.2–2.3), with pregnancy (PR: 1.5; CI95%: 1.0–2.1) and was more prominent among residents in Poxo Muybu (PR: 1.9; CI95%: 1.0–3.4) and Sawré Aboy (PR: 2.5; CI95%: 1.4–4.4) villages. Our findings suggest that chronic mercury exposure causes harmful effects to the studied indigenous communities, especially considering vulnerable groups of the population, such as women of childbearing age. Lastly, we propose to stop the illegal mining in these areas and develop a risk management plan that aims to ensure the health, livelihoods, and human rights of the indigenous people from Amazon Basin.
Highlights
Mercury (Hg) is a heavy metal ubiquitously distributed in the environment [1]
To estimate the prevalence of human mercury exposure in the study area, we considered the number of people who presented mercury levels ≥6.0 μg/g as the numerator, and the denominator as the population sampled in the study region, according to the villages: Sawré Muybu, Poxo Muybu, and Sawré Aboy
The average monthly income of families was USD 294.10 ranging from USD 201.0 to USD 414.5, with averages in Poxo Muybu slightly higher and Sawré Aboy somewhat lower
Summary
Mercury (Hg) is a heavy metal ubiquitously distributed in the environment [1]. humans have used this metal since ancient times [2], the increasing use of mercury in the last decades has caused important changes in their biogeochemical cycle and, the risk of becoming ill due to exposure to this contaminant has become a public health concern [3,4,5,6].In Brazil, studies developed since the 1980s point out that the artisanal small-scale gold mining activities (ASGM) in the Amazon are the main cause of environmental contamination by mercury in the region [7,8,9,10,11,12]. In a recent study conducted by Teixeira et al [15], mineralogical analysis carried out on soil samples from the region of Cachoeira do Piriá (state of Pará) revealed high concentrations of mercury, above the limit established by Brazilian environmental legislation, despite the absence of mineral formations constituted by mercury (i.e., despite the absence of natural mercury). These results make even more the contribution of the ASGM ( called garimpo) to environmental mercury contamination and indicate that the presence of natural mercury in the Amazon’s soil is not homogenous
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