Human exposure and risk assessment associated with mercury contamination in artisanal gold mining areas in the Brazilian Amazon

Hydrogeochemical characteristics and air quality risks associated with gold mining operations in Egypt using geochemical modeling and risk indices

The success of industrial operations depends on the effective identification, appraisal, and mitigation of possible hazards and associated environmental concerns. This report provides a complete review of environmental management techniques at the Sukari Gold Mine (SGM), located in the southeastern desert of Egypt. Extensive environmental measurements were taken to assess air and water quality, identify hazards, and analyze risks on the SGM premises. Air quality and noise intensity levels were measured at 39 places around the mine's working region. The findings found noncompliance with the Egyptian Environmental Law's (EEL4/94) noise exposure limitations, with the Power Generator House having the maximum noise levels at 107 dB. Remedial measures such as personal protective equipment (PPE) and exposure limit reduction strategies are being considered to address elevated noise levels. Measurements of particulate matter (PM10) and noxious gases (e.g., CO, SO2, NO2, HCN, and NH3) were conducted in workplace and ambient environments. Elevated PM10 concentrations were particularly concerning in underground regions, forcing the deployment of water depression techniques and improved PPE measures. While gas emissions from most activities remained under regulatory limits, select zones showed hydrogen cyanide (HCN) levels that exceeded permitted thresholds, necessitating specific control actions. Using hazard index (HI) and risk rating assessments, this study found different risk profiles across SGM's workplaces, focusing on high-risk regions for focused intervention. Additionally, a water assessment near a Tailing Storage Facility (TSF) was conducted to monitor the impact of mining activities on groundwater quality. The study revealed that groundwater in the region belongs to the Na-K-Cl-SO4 and Ca-Mg-Cl-SO4 water classes, with potential degradation attributed to high mineralization processes induced by aquifer materials and seawater intrusion. The findings underscore the importance of ongoing monitoring, control measures, and implementation of programs to ensure environmental sustainability and minimize risks associated with mining activities in the Sukari Gold Mines. This research highlights the imperative of continuous monitoring, proactive control measures, and the implementation of environmental initiatives to ensure the sustainability of mining operations within the Sukari Gold Mines.

Genomic investigation on genes related to mercury metabolism in Amazonian indigenous populations

Studies have identified elevated levels of mercury in Amazonian Indigenous individuals, highlighting them as one of the most exposed to risks. In the unique context of the Brazilian Indigenous population, it is crucial to identify genetic variants with clinical significance to better understand vulnerability to mercury and its adverse effects. Currently, there is a lack of research on the broader genomic profile of Indigenous people, particularly those from the Amazon region, concerning mercury contamination. Therefore, the aim of this study was to assess the genomic profile related to the processes of mercury absorption, distribution, metabolism, and excretion in 64 Indigenous individuals from the Brazilian Amazon. We aimed to determine whether these individuals exhibit a higher susceptibility to mercury exposure. Our study identified three high-impact variants (GSTA1 rs1051775, GSTM1 rs1183423000, and rs1241704212), with the latter two showing a higher frequency in the study population compared to global populations. Additionally, we discovered seven new variants with modifier impact and a genomic profile different from the worldwide populations. These genetic variants may predispose the study population to more harmful mercury exposure compared to global populations. As the first study to analyze broader genomics of mercury metabolism pathways in Brazilian Amazonian Amerindians, we emphasize that our research aims to contribute to public policies by utilizing genomic investigation as a method to identify populations with a heightened susceptibility to mercury exposure.

A picture of artisanal and small-scale gold mining (ASGM) in Brazil and its mercury emissions and releases

This study presents a picture of ASGM in Brazil and prospective numbers on mercury emissions and releases in 2016, when the country declared production of about 90 tonnes of gold, of which circa 25 tonnes came from ASGM. However, it is also necessary to consider the illegal production of ASGM which is estimated to vary between 10% and eight times more than the legal production. The proposed method included: organization of spatial data on legal ASGM output, stakeholder identification and meetings, mercury metallurgical balance, quantitative measurement of mercury in the atmosphere and qualitative social aspects such as the miners' economic dependence on the managers and scenarios of illegal ASGM annual production. The main results revealed that the initial mercury (Hg)-gold (Au) production ratio was higher for the primary whole ore than for the concentrate secondary ore, which is the most frequent type of Brazilian ASGM. The amalgam filtering technique followed by mercury recovery is routine, decreasing the Hg releases to tailings ponds or to soil and water bodies. The mercury emissions by thermal decomposition of amalgam are independent of the initial mercury mass, depending only on the mercury in the amalgam and the (adequate) use or not of emission control systems. Illegal activities reduce the availability and proper use of these systems, resulting in higher emissions. Mercury emissions from ASGM in Brazil may increase the global mercury emissions estimates, while their mercury releases may represent a marginal increase. As the mercury emitted may be trapped by the rainforests added to the mercury released, the environmental contamination may pose health risks to Amazonian population, which requires immediate action.

Health risk assessment and quality reference values of potentially toxic elements in soils of the Southwestern Amazonas State - Brazil

The geochemical processes involved in the Amazon soils formation are not totally understood because its geological and pedological features were formed during different geological events and different times. The Southwestern region of Amazonas State is an example of a region where the soils were developed from rocks formed by sedimentary processes and, nowadays, the soils continue receiving seasonal inputs from the Andes sediments. Data on geochemical patterns of this region are scarce, and there is no information about the possible effects of the natural or unnatural enrichment of potentially toxic elements (PTEs). Thus, this study represents the first research into the geochemical patterns of PTEs in soils of Southwestern Amazonas State. Further, we carried out a human health risk assessment and a proposal for Quality Reference Values (QRV) for thirteen PTEs (As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Ti, V, Zn and Zr). Our findings showed that the PTEs contents in soil samples collected in the lowland areas are strongly influenced by sediments inputs, while samples localized in the highland areas are weakly influenced by sediments inputs and present depletion of PTEs. Barium, Cr, Cu, Ni and Pb were the PTEs most influenced by sediment's deposition. The soil contamination assessment showed the existence of enrichment of the potentially toxic elements in soil samples, which may be a consequence of the natural inputs of the Andean sediments. Furthermore, Co and Cr exceed the safety zone for carcinogenic risk assessment, which indicates the need to monitor these elements and their possible effects on the health of the population in this region.

Historical Hg accumulation (∼65 cal kyr BP) in upland lakes of the Southeastern Brazilian Amazonia: New evidence of the extent of geogenic and diagenetic control

The historical upland lake sediments in the Brazilian Amazon witnessed significant enrichment of total mercury (Hg). However, its spatio-temporal relationships between lakes and the main factors responsible for this enrichment are still poorly constrained. Given this, we geochemically investigated 12 radiometrically dated (extending back to ∼65 cal kyr BP) sediment cores from the Carajás plateau, Brazil. The Hg level in historical sediments presented a large temporal variability (from 1 to 3200 μg/kg), with maximum accumulation peaks observed between 30 and 45 cal kyr BP in core R2, LB3, and R1. However, the lack of the Hg peak in other cores (LV2 and LTI3) during the same period despite being proximity and non-correlation of these Hg peaks with the onset of major volcanic events indicates that this source has little bearing. Hg enrichment is highly dependent on the type of sedimentary facies, with higher values were associated with detritic facies (MI) and detritic+organic facies (P/M). Principal component analysis shows that aluminosilicate minerals and organic matter are essential hosts of Hg in sediments. The positive correlation between Al, Ti, and Hg in detritic facies and their strong coherence with Hg/TOC in R1, R5, LSL, ST02, and LB3 cores indicate that Hg is primarily of lithogenic origin. This can be substantiated by the higher background threshold value of Hg (574 μg/kg) in historical lake sediments compared to those in recent lake sediments (340 μg/kg). However, the most pronounced Hg peak (3200 μg/kg) in R2 around 45 cal kyr BP, which correlates positively with TOC, S, Se, As, and Mo indicates their diagenetic enrichment in organic-rich sediments under anoxic conditions. Thus, in addition to the lithogenic effect, it can be argued that diagenesis can play a significant role in prompting Hg enrichment in the Carajás lake sediments in Amazonia.

Analysis of Mercury in Aquifers in Gold Mining Areas in the Ecuadorian Amazon and Its Associated Risk for Human Health

Gold mining activity is a source of supply in many areas of the world, and especially in developing countries, it is practiced illegally and by applying unsafe techniques. Particularly in Ecuador, artisanal and small-scale gold mining (ASGM) is widespread, and it is based on the use of toxic substances, such as mercury (Hg), in gold recovery. Hg is a heavy metal that is water-insoluble, which, once mobilized, poses a threat to both the environment and human health. This study analyzes Hg concentrations in the six provinces of Napo, Sucumbíos, Orellana, Pastaza, Morona Santiago, and Zamora Chinchipe of the Ecuadorian Amazon region to conduct a human health risk assessment. Significant differences in Hg levels were found between provinces, but concentrations were below MPL imposed by Ecuadorian regulations everywhere. Nevertheless, a worrisome picture emerges, especially with regard to the most vulnerable receptors represented by the child population. There are multiple factors of incidence that may affect the possible future development of the phenomenon, and with reference to the social, economic, and environmental context of the region, it can be concluded that it may be appropriate to plan further investigation to arrive at a more comprehensive assessment. The results of this study can be used by decision makers to plan further investigation and to implement monitoring networks, risk mitigation strategies, and groundwater protection measures.

Human Health Risk Assessment from Mercury-Contaminated Soil and Water in Abu Hamad Mining Market, Sudan

Artisanal and small-scale gold mining (ASGM) poses a significant global threat due to mercury emissions and resulting health hazards. This study focuses on assessing these risks in the Abu Hamad ASGM community in Sudan. Utilizing the Mercury Analyzer 3000 (NIC), analyses of twelve soil samples (including one tailings sample) and seven water samples revealed the highest concentrations near amalgam burning locations: 34.8 mg/kg in soil (S06) and 3.26 µg/L in water (W03). Concentrations decrease with distance, with soil near burning exceeding tailings (S05 = 19.0 mg/kg). Hazard quotients indicate mercury vapor inhalation as the primary exposure route from soil, with the Hazard Index reaching 5.34 for adults and 33.4 for children close to amalgam burning sites. Water samples generally pose little risk except for W03, where children face potential danger via ingestion (HI = 1.74). These findings emphasize the urgent need for adopting retorts and eco-friendly practices to reduce mercury emissions and protect ASGM communities.

Evaluation of exposure to multiple organic pollutants in riparian communities of the Brazilian Amazon: Screening levels and potential health risks

Organic pollutants are widely distributed in the environment. Due to their physical and chemical characteristics, they tend to be biomagnified in food chains, mainly in aquatic organisms. Therefore, food consumption is a significant route of lifelong exposure. Although the Amazon River basin contains the highest freshwater biodiversity on Earth, there is scarce literature focusing on the levels of organic pollutants in the local population. The present study was aimed at assessing the levels of several environmental pollutants (polycyclic aromatic hydrocarbons, bisphenols, parabens, and benzophenones) in urine samples from riverside communities along the Tapajós and Amazon Rivers in the Brazilian Amazon region. The results show a 100 % detection of naphthalene metabolites (namely, 1-hydroxy-naphthalene (1OH-NAP), 2-hydroxy-naphthalene (2OH-NAP)), with the highest levels belonging to benzylparaben (BzP) (17.3 ng/mL). Gender-specific analysis revealed that women had significantly higher levels of certain PAH metabolites (i.e., 1OH-NAP and 2-hydroxy-fluorene (2OH-FLU)) than men. In turn, most of the evaluated compounds were higher in urine samples from people living near the Amazon River, which presents increased traffic of boats and ships than the Tapajós River. On the other hand, the human health risk assessment suggested that all communities are at risk of suffering non-carcinogenic effects from exposure to PAHs. At the same time, they are also at risk of carcinogenic effects from exposure to benzo[a]pyrene metabolites. Thus, further studies are needed in order to evaluate the potential health effects of exposure to a mixture of these organic pollutants and other contaminants present in the area, such as mercury.

Influence of a hydroelectric dam on fish mercury contamination along the Sinnamary River (French Guiana)

The Petit Saut hydroelectric dam and the upstream and downstream areas of the Sinnamary River in French Guiana (Amazon basin) have been studied from 1993 to 2020. The nearly thirty-years-long study of the monitoring of total mercury concentration in fish and the physicochemical survey of the environment made it possible to demonstrate the impact of the flooding of the forest and the role of the hydroelectric dam on the methylation of mercury. Results show that the physicochemical modifications generated by the construction of the dam led to a significant production of methylmercury (MeHg) in the anoxic part of the reservoir and downstream of the river leading to a strong spatio-temporal impact of the dam. Seven species of fishes are studied and their mercury concentrations vary according to many parameters: fish diet, position in the water column, site, lake oxycline level and time.

Assessing mercury pollution at a primary ore site with both ancient and industrial mining and smelting activities

The Minamata Convention on Mercury has mandated a renewed global effort to tackle Hg pollution. The present study evaluates Hg pollution at a primary Hg production site exploited since the Qin Dynasty (200s BC), with intensive industrial scale production over the past four decades. This single location accounts for over 95% total Hg production in China in recent years. To assess the environmental risk and effectiveness of recently implemented control measures, we collected 90 soil samples, 60 plant tissue samples, 47 sediment samples, and 47 river water samples from the site and its vicinity. A site-specific conceptual site model was established based on the sources, migration transformation pathways of Hg pollutant and its exposure scenarios. The maximum soil Hg concentration reached 10,451 mg kg-1, posing a high health and ecological risk. Vegetable and crop Hg concentrations outside the site reached 0.23 mg kg-1 in rice grains and 4.24 mg kg-1 in green onion. The highest health risk, with a hazard quotient of 130.66, was observed in the Ore Storage Site, which reduced to 17.14 when Hg bioavailability was considered. Risk control measures implemented in recent years included a stormwater collection system and capping of the tailing pond area with clean imported soil. These measures were generally successful; however, Hg in the tailings were found to be contaminating the imported surficial soil due to rainfall saturation and upward migration, suggesting a need for long-term post remedial site monitoring and maintenance. We also found that mining and smelting activities have contaminated a 6 km stretch of a nearby river, with sediment Hg concentrations reaching 2819 mg kg-1, and water column concentrations reaching 193.21 ng L-1. The sediment and water concentrations are highly correlated (R2 = 0.78), suggesting that, with risk control measures in place, a reservoir of Hg in polluted river sediment is now driving pollution in the water column. This work demonstrates that primary Hg mining has caused widespread and serious soil and water pollution. Risk control measures can reduce human health and ecological risks, but robust monitoring and maintenance are required for remediation to be effective in the long-term.

Assessment of Hg pollution in stream waters and human health risk in areas impacted by mining activities in the Ecuadorian Amazon

Illegal gold mining activities have contributed to the release and mobilization of Hg and environmental degradation in many parts of the world. This study aims to determine the concentration of Hg in five provinces of the Amazon Region of Ecuador, in addition to assessing the risk to human health of exposed populations, applying deterministic and probabilistic methods. For this purpose, 147 water samples were collected in rivers and streams crossing and/or located near mining areas. As a result, 100% of the samples analyzed exceeded the maximum permissible limit (MPL) according to the water quality criteria for the preservation of aquatic life of the Ecuadorian regulations, while 7% of the samples exceeded the MPL for drinking water. On the other hand, considering the European Environmental Quality Standard (EQS) for surface water bodies, in our study, 100% of the samples exceed the maximum permissible limit (0.07 µg/L), and with respect to the Canadian water quality guidelines, 35% of the samples exceed the permissible limit (0.001 mg/l) for drinking water, and 100% of the samples exceed the limit for life in water bodies (0.0001 mg/l). The risk assessment revealed that the probability of developing adverse health effects from exposure to Hg is below the recommended limits according to the probabilistic assessment; this is in relation to the criterion of residential and recreational use of water resources. However, it was identified that the child population doubles the acceptable systemic risk level according to the results of the deterministic assessment in the residential scenario. This information can be used by decision-makers to implement strategies to reduce Hg contamination and exposure of the population in Ecuadorian Amazonian rivers.

Total Mercury Content in the Tissues of Freshwater Chelonium (Podocnemis expansa) and a Human Health Risk Assessment for the Amazon Population in Brazil

Researchers recognize the silent, negative and deleterious effects caused by mercury pollution in gold mining areas. Freshwater turtles are culturally part of the diet of riverside populations in the Amazon region and this area presents mercury (Hg) pollution issues mainly due to gold mining activities. Thus, this research aimed to evaluate the total mercury (THg) content in the different organs of Amazonian giant river turtle (Podocnemis expansa) and carry out a human health risk assessment associated with the consumption of these animals. This study was conducted in the Vila Balbina, municipality of Presidente Figueiredo, state of Amazonas, Brazil. Skin (n = 28), muscle (n = 19) and brain (n = 2) samples were analyzed by Atomic Absorption Spectrometry (TDA-AAS) and a DMA-80™ mercury analyzer was used for the total mercury determinations. The average values found for THg in the skin, muscle and brain samples were, respectively, 0.1045 mg·kg-1, 0.1092 mg·kg-1 and 0.0601 mg·kg-1. Thus, THg was observed even though the P. expansa were kept in captivity, possibly due to previous contamination by air, water and food. The Hazard Quotient (HQ) was calculated considering a 9.07 g·day-1 intake dose of P. expansa and the consumption of turtles once a week showed an HQ = 2.45, which may cause long-term injuries to human health. Although the muscle concentrations were below the maximum limit established by the World Health Organization (WHO) and Brazilian regulatory agencies, it is important to evaluate consumption factors such as amount ingested, frequency and animal gender, which may cause a potential risk to regular consumers due to mercury bioaccumulation. The WHO may consider various aspects in order to warn the Amazon population about the severity and silent hazard of this metal, especially due to the importance of this matrix in the region. This region urgently needs government actions to inhibit clandestine mining and to prevent future serious, chronic health problems of the entire population.

Human health risk assessment of metals and metalloids in mining areas of the Northeast Andean foothills of the Ecuadorian Amazon

Gold mining (GM) is a major source of metals and metalloids in rivers, causing severe environmental pollution and increasing the exposure risks to the residents of surrounding areas. Mining in Ecuadorian Amazonia has dramatically increased in recent years, but its impacts on Indigenous local populations that make use of rivers are still unknown. The aim of this study was to assess the risks to adults and children caused by the exposure to metals and metalloids in freshwater ecosystems contaminated with tailings released by GM activities in 11 sites of the upper Napo River basin, Ecuador. We selected a carcinogenic and a noncarcinogenic risk assessment method to estimate the hazard index (HI) and total cancer risk (TCR). The concentration of Ag, Al, As, Cd, Cu, Fe, Mn, Pb, Zn, B, and V in water and sediment samples was considered to assess the risks to human health. The calculated HI was 23-352 times greater than the acceptable limits in all sites for both children and adults. Mn and Fe were the main contributors (75% in water and 99% in sediment) to the total calculated risk based on the HI. The calculated TCR for children and adults exceeded approximately one to three times the permissible threshold in all sites. As and Pb contributed up to 93% of the total calculated risk based on TCR for both children and adults. This study demonstrates that the emission and mobilization of metals and metalloids caused by mining activities increase the risk to human health, to which we recommend further monitoring of freshwater contamination in the area and the implementation of preventive health management measures. Integr Environ Assess Manag 2023;19:706-716. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Astrocyte-Like Cells Transcriptome Changes After Exposure to a Low and Non-cytotoxic MeHg Concentration

The central nervous system is the main target of MeHg toxicity and glial cells are the first line of defense; however, their true role remains unclear. This study aimed to identify the global map of human glial-like (U87) cells transcriptome after exposure to a non-toxic and non-lethal MeHg concentration and to investigate the related molecular changes. U87 cells were exposed upon 0.1, 0.5, and 1 µM MeHg for 4 and 24 h. Although no changes were observed in the percentage of viable cells, the metabolic viability was significantly decreased after exposure to 1 µM MeHg for 24 h; thus, the non-toxic concentration of 0.1 µM MeHg was chosen to perform microarray analysis. Significant changes in U87 cells transcriptome were observed only after 24 h. The expression of 392 genes was down regulated while 431 genes were up-regulated. Gene ontology showed alterations in biological processes (75%), cellular components (21%), and molecular functions (4%). The main pathways showed by KEGG and Reactome were cell cycle regulation and Rho GTPase signaling. The complex mechanism of U87 cells response against MeHg exposure indicates that even a low and non-toxic concentration is able to alter the gene expression profile.

Spatial distribution of total mercury and methylmercury in the sediment of a tropical coastal environment subjected to heavy urban inputs

Jurujuba Cove is located in Guanabara Bay (adjacent to highly populated city of Rio de Janeiro, Brazil), which receives diffuse sources of contaminants along with two main freshwater inputs (the Cachoeira and Icaraí rivers), and hosts mussel farms. The main goal of this work was to evaluate the total mercury (THg) and methylmercury (MeHg) concentrations distributions in the sediments of the cove and their associations with physical and chemical parameters, thereby assessing their geochemical behavior. Twenty samples of surface sediments were collected and characterized for grain size, pH, redox potential, organic carbon, total phosphorus, THg and MeHg. Spatial distribution maps were produced for each parameter and a principal components analysis was carried out, to assess THg and MeHg behavior and their relationships with other parameters. The principal components analysis showed that grain size functions as the main diluting agent. The highest THg concentrations were observed in the mussel-farm area (656.1 ng g^-1), and were related to fine grain size and elevated organic carbon values. High MeHg concentrations also occurred in the center of the cove, probably favored by high organic carbon content (low-energy environment). Total phosphorus concentrations indicate that Cachoeira River is a possible source of sewage, but little mercury seems to come from it. The results showed that although total mercury concentrations are elevated, with exception of a few locations, small methylmercury convertion rates were recorded in the sediments.

Ecological risk assessment of metal and hydrocarbon pollution in sediments from an urban tropical estuary: Tijuca lagoon (Rio de Janeiro, Brazil)

Urban tropical lagoons are often impacted by eutrophication, metal, and polycyclic aromatic hydrocarbon (PAH) contamination, but the toxicity of their bottom sediments is still poorly investigated in South America. Aiming to contribute to filling this gap, a sediment quality assessment was conducted in the Tijuca Lagoon (Rio de Janeiro, Brazil) using different lines of evidence (LOEs) including sediment characterization, determination of metals and PAHs, and acute toxicity testing with burrowing amphipods (Tiburonella viscana). Mud and organic matter contents played a crucial role in contaminant distribution along the lagoon. The concentrations of PAH were generally low (mean ΣPAH = 795.42 ± 1146.2 ng/g; n = 23), but a contamination hotspot of light PAH compounds was identified. Such PAHs were mainly pyrolytic, probably related to the deposition of atmospheric pollution, although petrogenic compounds also occur in the lagoon. The data indicated the occurrence of geochemical anomalies of Zn, Cu, Pb, and Hg (mean values = 176.9 ± 91.6, 45.1 ± 21.3, 35.2 ± 15.0, 0.1442 ± 0.0893 mg/kg, respectively; n = 23), probably associated with industrial wastes, garbage deposition, urban runoff, and domestic sewage contributions. The mortality of T. viscana was significant for more than 85% of the samples (mean mortality = 70.3 ± 26.0%; n = 23), but it was not significantly correlated with PAH and metal concentrations. On the other side, domestic sewage contributions and eutrophication seem to play a relevant role in sediment toxicity. Actually, the toxicity observed in the tests seems to be due to the simultaneous influence of multiple toxicants and their combined effects on the organisms. Such stressors may include not only metals, PAH, and eutrophication but also chemicals not evaluated in this study, such as hormones, pharmaceuticals and personal care compounds, perfluorocompounds, detergents, and others.

A Bibliometric Analysis of the Scientific Research on Artisanal and Small-Scale Mining

Mineral resource exploitation is one of the activities that contribute to economic growth and the development of society. Artisanal and small-scale mining (ASM) is one of these activities. Unfortunately, there is no clear consensus to define ASM. However, its importance is relevant in that it represents, in some cases, the only employment alternative for millions of people, although it also significantly impacts the environment. This work aims to investigate the scientific information related to ASM through a bibliometric analysis and, in addition, to define the new lines that are tending to this field. The study comprises three phases of work: (i) data collection, (ii) data processing and software selection, and (iii) data interpretation. The results reflect that the study on ASM developed intensively from 2010 to the present. In general terms, the research addressed focuses on four interrelated lines: (i) social conditioning factors of ASM, (ii) environmental impacts generated by ASM, (iii) mercury contamination and its implication on health and the environment, and (iv) ASM as a livelihood. The work also defines that geotourism in artisanal mining areas is a significant trend of the last decade, explicitly focusing on the conservation and use of the geological and mining heritage and, in addition, the promotion of sustainable development of ASM.

Risk Assessment of Mining Environmental Liabilities for Their Categorization and Prioritization in Gold-Mining Areas of Ecuador

Mining environmental liabilities (MEL) are of great concern because of potential risks to ecosystems and human health. In this research, the environmental risk (RI) related to MEL existing in three artisanal and small-scale gold-mining areas of Ecuador was evaluated. For this purpose, data of 167 MEL including landfills, mining galleries, tailing deposits, and mineral processing plants from Macuchi, Tenguel–Ponce Enriquez, and Puyango mining areas, were analyzed. The risk assessment related to the presence of waste deposits was carried out based on the methodology proposed by the Spanish Geological Survey. Moreover, the procedure outlined in the Environmental Risk Assessment Guide of the Ministry of Environment of Peru for nonwaste deposits was applied. The highest RI values were identified in Puyango and Tenguel–Ponce Enriquez. Thus, they were both categorized as priority control areas requiring intervention and rehabilitation plans. The MEL that require a high level of intervention include waste deposits and mine entrances associated with potentially toxic elements. Moreover, the point risk maps showed that rivers in the studied areas have a potential pollution risk. This study provides risk levels associated with MEL in mining areas from Ecuador. This information could be used for environmental management and pollution mitigation.

Fundão tailings dam failure in Brazil: Evidence of a population exposed to high levels of Al, As, Hg, and Ni after a human biomonitoring study

BACKGROUND

On November 5th, 2015, the Fundão mine tailings dam in Minas Gerais State, Brazil, failed, releasing more than 50 million m³ of mud, rich in toxic metals. After that, a massive environmental disaster began with the mud wave flowing more than 600 km, until the mouth of Doce River, in Espírito Santo State, and finally reaching the Atlantic Ocean. A vast area was contaminated, affecting the ecosystem and several communities. Despite the tremendous environmental disaster, little is known concerning the population's exposure to toxic elements yet.

METHODS

Thus, a cross-sectional study was for the first time conducted in three communities directly affected by the disaster (Regência, Povoação, and Campo Grande) in Espírito Santo State, to evaluate the levels of 11 chemical elements (Al, As, Cd, Co, Cu, Hg, Mn, Ni, Pb, Se, and Zn) in blood. Sample analysis (n = 300) was performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

RESULTS

Our data show high levels of exposure to Al, As, Hg, and Ni. Mean values in blood were 60 μg/L (ranging from 9 to 434 μg/L), 10.9 μg/L (ranging from 5.81 to 269 μg/L), 6.4 μg/L (ranging from 0.05 to 103 μg/L) and 2.7 μg/L (ranging from 0.08 to 21 μg/L) for Al, As, Hg and Ni, respectively. Moreover, after applying a multiple regression model, we found community, drinking water, fish, seafood consumption, and smoking habits associated with metal/metalloid levels in their body. Well and tap water intake were identified as important sources of exposure to aluminum and nickel.

CONCLUSIONS

Our findings represent health risks to the groups living in the areas affected by the tailings dam failure, calling for further studies to evaluate the potential health effects of high exposure to metals and remediation actions from public health Brazilian authorities.

Study of inorganic elements in different organs and tissues of Amazonian manatee (Trichechus inunguis) from Brazil

Multielement concentrations (P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Rb, and Rh) and total mercury (T-Hg) were analyzed in different organs and tissues of Amazonian manatee (Trichechus inunguis). Samples of 27 T. inunguis specimens, maintained in the collection of the Amazonian Center for the Research and Preservation of Aquatic Mammals, were used, situated in an area highly impacted by gold mining in the northern region of the Brazilian Amazon. Samples of aquatic plants used as food by the animals were also analyzed. The elements S, Cl, K, Cr, and Mn accumulated mainly in the musculature, while Fe and Cu were more concentrated in the liver. Trace elements, such as rubidium (Rb) and rhodium (Rh), not previously reported in the organs of animals of the family Trichechidae, were also identified. The averages for T-Hg in the skin, muscle, encephalon, liver, kidney, and lung samples were, respectively, 0.1540 ± 0.1332, 0.0593 ± 0.1044, 0.0517 ± 0.0467, 0.0486 ± 0.0543, 0.0237 ± 0.0336, and 0.0013 ± 0.0032 µg.g^-1. The values obtained for the vibrissae samples were below the limit of quantification, which allows for the conclusion that this tissue cannot be used as a contamination marker. It was observed that even when kept in a conservation breeding site, these animals were exposed to non-essential trace elements. Differences in the accumulation of elements were observed between the different organs and tissues analyzed. The presence of contaminants in animals that live in a preservation center, even at low levels, deserves attention.

Determination of 14 trace elements in blood, serum and urine after environmental disaster in the Doce River basin: Relationship between mining waste and metal concentration in the population

BACKGROUND

Exposure to chemical substances after an environmental disaster can cause both toxic effects and changes in the health status of people who live in or have proximity to environments of this nature, so that the concern with populations is growing.

METHODS

In this cross-sectional study, blood, serum and urine samples were collected from 100 volunteers from Santo Antônio do Rio Doce, eight from Ilha das Pimentas and 50 from the control group; and analyzed by inductively coupled plasma mass spectrometry for biomonitoring of Al, As, Ba, Cd, Co, Cu, Cr, Fe, Hg, Mn, Ni, Se, Pb, Zn. In addition, a comprehensive questionnaire was applied to collect demographic and socioeconomic information, as well as lifestyle.

RESULTS

The concentrations of As, Al, Cd, Ni and Mn were above the reference value in some biological matrices, with more pronounced exposure in Ilha das Pimentas. The concentrations of As, Cd, Cu, Co, Pb and Zn showed statistical differences regarding gender in the different biological matrices. The trace elements in the blood, serum and urine showed significant correlations when considering age and habits such as the consumption of cigarettes, alcoholic beverages and fish. The main correlations were observed between Co, Cr, Mn, Ni and Pb in the blood and cigarette consumption.

CONCLUSION

This is the first study in these regions after the environmental disaster and confirmation of the diagnosis and health care of the participants should be promoted for clinical investigation and the eventual need for treatment. Human biomonitoring demonstrated high concentrations of some toxic elements, with more accentuated exposure in Ilha das Pimentas.

Assessment of biomarkers of early kidney damage and exposure to pollutants in artisanal mercury mining workers from Mexico

Artisanal mercury mining (AMM) is an informal economic activity that employs low technology and limited protection, and poses a risk to workers and their families; due to the extraction process, these scenarios involve exposure to complex mixtures of pollutants that synergistically aggravate the health of miners and people living near the site. Although mercury is the predominant pollutant, there are others such as polycyclic aromatic hydrocarbons (PAHs), toluene, arsenic, and lead which have been classified as nephrotoxic pollutants. Therefore, the purpose of this research was to evaluate the association between exposure to a complex mixture of pollutants (mercury, lead, arsenic, PAHs, and toluene) and kidney damage in artisanal Hg mining workers through early kidney damage proteins (KIM-1, OPN, RBP-4, NGAL, and Cys-C). The results demonstrate the presence of OH-PAHs at concentrations of 9.21 (6.57-80.63) μg/L, hippuric acid as a biomarker of exposure to toluene, As and Pb (655. 1 (203.8-1231) mg/L, 24.05 (1.24-42.98) g/g creatinine, and 4.74 (2.71-8.14) g/dL, respectively), and urinary Hg (503.4 (177.9-878.7) g/g creatinine) in the study population. As well as biomarkers of kidney damage, NGAL and RPB-4 were found in 100% of the samples, KIM-1 and Cys-C in 44.1%, and OPN in 41% of the miners. Significant correlations were found between several of the evaluated pollutants and early kidney damage proteins. Our results demonstrate the application of the early kidney damage biomarkers for the assessment of damage caused by the exposure to mixtures of pollutants and, therefore, the urgent need for monitoring in AMM areas.

A new species of Hoplias malabaricus species complex (Characiformes: Erythrinidae) from the Crepori River, Amazon basin, Brazil

A new species belonging to the Hoplias malabaricus complex from the Amazon basin, Brazil, is described. The new species is characterized by 15-16 predorsal scales, 37-39 lateral-line scales, 5 scales from dorsal fin to lateral line, 38-39 vertebrae, iii-iv, 7-8 anal-fin rays, ii-iv, 12-15 caudal-fin rays, last vertical series of scales on the base of caudal-fin rays forming a straight line, 6-7 dark bands in anal fin and no distinctive dark bands or blotches on flanks. The new species is also distinguished from other congeners of the H. malabaricus species-group by means of landmark-based morphometrics and DNA Barcoding (Cytochrome c Oxidase I gene). An identification key to species of the H. malabaricus species complex is provided.

Impact of copper mining wastes in the Amazon: Properties and risks to environment and human health

Improper disposal of copper mining wastes can threaten the ecosystem and human health due to the high levels of potentially toxic elements released into the environment. The objective of this study was to determine the properties of Cu mining wastes generated in the eastern Amazon and their potential risks to environment and human health. Samples of forest soil and artisanal/industrial Cu mining wastes were collected and subjected to characterization of properties and pseudo-total concentrations of Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, and Zn, in addition to chemical fractionation of Cu. The pH ranged from near neutrality to alkaline. Pseudo-total concentrations of Cu were high in all wastes, mainly in the artisanal rock waste, with 19,034 mg kg^-1, of which 61% is concentrated in the most reactive fractions. Pollution indices indicated that the wastes are highly contaminated by Cu and moderately contaminated by Cr and Ni. However, only the artisanal rock waste is associated with environmental risk. Non-carcinogenic and carcinogenic human health risks were detected, especially from exposure to Cr in the artisanal rock waste. Prevention actions and monitoring of the artisanal mining area are necessary to avoid impacts to the local population.

A Quantitative Assessment and Biomagnification of Mercury and Its Associated Health Risks from Fish Consumption in Freshwater Lakes of Azad Kashmir, Pakistan

Issues regarding biomagnification of mercury (Hg) due to its persistence, bioaccumulation, and toxicity in freshwater lakes have gained much attention in the last two decades especially in remote regions of the world where anthropogenic inputs are considered as negligible. In this study, spatial distribution of total mercury (THg), interspecific accumulation patterns, trophic transfer, and associated health risks in fish of freshwater lakes (357-3107 masl) in Azad Kashmir, Pakistan, were investigated. THg concentrations in the regions were 0.20 ± 0.08 μg g^-1 in glacial, 0.54 ± 0.21 μg g^-1 in rural, and 1.35 ± 0.46 μg g^-1 in urban region. Omnivorous, herbivorous, and carnivorous fish showed THg concentrations of 0.94, 0.85, and 0.49 μg g^-1. Regional, lake, trophic level, and specie-specific differences of THg accumulation were found significant in the study. Among growth parameters, length and age varied significantly among species, trophic levels, and lakes, whereas weight showed significant variation among lakes as well. Condition factor (K) showed significant differences within species, lakes, and trophic levels. Biomagnification was observed in all lakes with the trophic magnification slopes (TMS) ranging from 0.03 to 0.20 with an average of 0.094 ± 0.07. Isotopic values of nitrogen (δ¹⁵N) and condition factor were found to dominate THg accumulation trends; however, no significant health risks were found in the study.

Fish tissues for biomonitoring toxic and essential trace elements in the Lower Amazon

Brazilian soils can have high concentrations of toxic elements, mainly mercury (Hg) and arsenic (As), metals also associated with anthropogenic activities (e.g. intensive agriculture, mining, deforestation and hydroelectric plants). This can lead to large amounts of these elements reaching and/or being mobilized in the aquatic ecosystem, which constitutes a serious threat to the environment and to the health of local populations. Thus, we evaluate the feasibility of analyzing the tissues of freshwater fish species for monitoring toxic and trace element accumulation within the aquatic ecosystem in the Lower Amazon, Brazil. Two fish species were considered: Cichla temensis (Tucunaré), a carnivorous species, and Pterygoplichthys pardalis (Acari), a detritivorous species. Samples of liver and muscle from both species were evaluated in relation to their potential use for biomonitoring purposes. The study findings clearly demonstrate the value these fish species and tissues, particularly liver, for biomonitoring toxic and trace element concentrations in the aquatic environment across the study region. While Tucunaré liver proved the best option for biomonitoring elements that accumulate through the food chain (e.g. Hg), Acari liver better reflected elements that typically accumulate in the sediments (e.g. As). Moreover, the trace element profiles, determined using chemometric (multivariate) techniques, differed greatly in specimens from waters in the Andean mountain range (sampling sites located in the main course of the Amazon River) with high sediment concentrations, and in specimens from the Guyana and Brazilian shields (Porto Trombetas on the Trombetas River and Itaituba on the Tapajós River). The findings also indicate that deposition of elements in freshwater fish in this area is mainly associated with the geological origin of the soils and that large amounts of toxic elements can reach the aquatic ecosystem due to anthropogenic activities, thereby posing a serious danger to the environment and the health of the riverside communities.

Effects of mercury at field estimated concentration in brain of Bombus atratus (Hymenoptera: Bombini)

Although mercury neurotoxic effects are well known in several species, it is poorly studied in bees. Mercury contamination is increasing in several regions of the Brazilian Amazon Rainforest due to illegal and indiscriminate gold mining. Therefore, this study aimed to evaluate the effects of mercury (Hg) in brain Kenyon cells of foraging workers of Bombus atratus exposed to an average concentration (110 ppb) found in pots of honey from native bees of South America and Australia. Twenty forager workers were collected in the field (23° 34' S 47° 31' W), divided into control (n = 10) and exposed (n = 10) groups, and individually kept in special boxes for 48 h. For the exposed group, we offered Hg solution (at 110 ppb) ad libitum, while for the control group we offered water, and for both sucrose syrup at 70%. After the exposure time, the bees were crio-anesthezied at 4 °C. Brains were dissected and processed for morphological, morphometric, and histochemical analyses. Morphological results showed that the Kenyon cells of the Hg-exposed group presented both cytoplasmic vacuolization and nuclear pyknosis, which indicate cell death. These findings were corroborated by the acridine orange staining. Hg exposure also induced significant nuclear chromatin compaction in Kenyon cells. The calyces and peduncles of the mushroom bodies showed disorganization and vacuolization. In summary, these changes may imply in a severe impairment of the cognitive abilities of the bees, which could lead them to the loss of many tasks, such as foraging or even nest founding by the queen.

Methylmercury-induced cytotoxicity and oxidative biochemistry impairment in dental pulp stem cells: the first toxicological findings

BACKGROUND

Methylmercury (MeHg) is a potent toxicant able to harm human health, and its main route of contamination is associated with the consumption of contaminated fish and other seafood. Moreover, dental amalgams are also associated with mercury release on human saliva and may contribute to the accumulation of systemic mercury. In this way, the oral cavity seems to be the primary location of exposure during MeHg contaminated food ingestion and dental procedures but there is a lack of literature about its effects on dental tissues and the impact of this toxicity on human health. In this way, this study aimed to analyze the effects of different doses of MeHg on human dental pulp stem cells after short-term exposure.

METHODS

Dental pulp stem cells from human exfoliated deciduous teeth (SHED) were treated with 0.1, 2.5 and 5 µM of MeHg during 24 h. The MeHg effects were assessed by evaluating cell viability with Trypan blue exclusion assay. The metabolic viability was indirectly assessed by MTT reduction assay. In order to evaluate an indicative of antioxidant defense impairment, cells exposed to 0.1 and 5 µM MeHg were tested by measuring glutathione (GSH) level.

RESULTS

It was observed that cell viability decreased significantly after exposure to 2.5 and 5 µM of MeHg, but the metabolic viability only decreased significantly at 5 µM MeHg exposure, accompanied by a significant decrease in GSH levels. These results suggest that an acute exposure of MeHg in concentrations higher than 2.5 µM has cytotoxic effects and reduction of antioxidant capacity on dental pulp stem cells.

Human Health Risk Assessment for Exposure to Potentially Toxic Elements in Polluted Rivers in the Ecuadorian Amazon

Anthropogenic activities performed in the Ecuadorian Amazon have released potentially toxic elements (PTEs) into the rivers, causing severe environmental pollution and increasing the risk of exposure to the residents of the surrounding areas. This study aims to carry out a human health risk assessment using deterministic and probabilistic methods to estimate the hazard index (HI) and total cancer risk (TCR) related to multi-pathway human exposure to PTEs in polluted rivers. Concentrations of Al, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in surface water and sediment samples from rivers on the Ecuadorian Amazon were considered to assess the potential adverse human health effects. As a result, deterministic and probabilistic estimations of cancer and non-cancer risk through exposure to surface waters and sediments were above the safety limit. A sensitivity analysis identified the concentration of PTEs and the exposure duration (ED) as the two most important variables for probabilistic health risk assessment. The highest risk for receptors was related to exposure to polluted sediments through incidental ingestion and dermal contact routes. According to the deterministic estimation, the human health risk through ingestion of water was above the threshold in specific locations. This study reveals the potential health risk to which the population is exposed. This information can be used as a baseline to develop public strategies to reduce anthropogenic pollution and exposure to PTEs in Ecuadorian Amazon rivers.

Health Studies in the Context of Artisanal and Small-Scale Mining: A Scoping Review

Artisanal and small-scale mining (ASM) is an important livelihood activity in many low- and middle-income countries. It is widely acknowledged that there are a myriad of health risk and opportunities associated with ASM. However, little is known with regard to which aspects of health have been studied in ASM settings. We conducted a scoping review of peer-reviewed publications, using readily available electronic databases (i.e., PubMed, Scopus, and Web of Science) from inception to 14 July 2020. Relevant information was synthesized with an emphasis on human and environmental exposures and health effects in a context of ASM. Our search yielded 2764 records. After systematic screening, 176 health studies from 38 countries were retained for final analysis. Most of the studies (n = 155) focused on health in ASM extracting gold. While many of the studies included the collection of environmental and human samples (n = 154), only few (n = 30) investigated infectious diseases. Little attention was given to vulnerable groups, such as women of reproductive age and children. Our scoping review provides a detailed characterisation of health studies in ASM contexts. Future research in ASM settings should address health more comprehensively, including the potential spread of infectious diseases, and effects on mental health and well-being.

Neurotoxicity of mercury: an old issue with contemporary significance

Mercury exerts a variety of toxic effects, depending on the specific compound and route of exposure. However, neurotoxicity in virtue of its consequence to health causes the greatest concern for toxicologists. This is particularly true regarding fetal development, where neurotoxic effects are much more severe than in adults, and the toxicity threshold is lower. Here, we review the major concepts regarding the neurotoxicity of mercury compounds (mercury vapor; methylmercury and ethylmercury), from exposure routes to toxicokinetic particularities leading to brain deposition and the development of neurotoxic effects. Albeit research on the neurotoxicity of mercury compounds has significantly advanced from the second half of the twentieth century onwards, several grey areas regarding the mechanism of toxicity still exist. Thus, we emphasize research advances during the last two decades concerning the molecular interactions of mercury which cause neurotoxic effects. Highlights include the disruption of glutamate signaling and excitotoxicity resulting from exposure to mercury and the interaction with redox active residues such as cysteines and selenocysteines which are the premise accounting for the disruption of redox homeostasis caused by mercurials. We also address how immunotoxic effects at the CNS, namely microglia and astrocyte activation modulate developmental neurotoxicity, a major topic in contemporary research.

Total mercury in commercial fishes and estimation of Brazilian dietary exposure to methylmercury

BACKGROUND

Mercury, in particular its most toxic form methylmercury, poses a risk to public health. Dietary methylmercury exposure is mainly by fish, and it can vary with fish contamination and by dietary habits of the population. This study aimed to quantify total mercury levels in different fish from Brazil and to estimate Brazilian exposure to methylmercury by fish consumption.

METHODS

Total mercury occurrence was investigated in 18 different fish species by atomic absorption spectrometry with thermal decomposition and gold amalgamation. Dietary exposure to methylmercury was estimated by a deterministic method for different groups considering consumption by sex, different Brazilian geographical regions and habitat (rural or urban).

RESULTS

Carnivorous fish showed higher levels of mercury (0.01 to 0.93 mg/kg) compared to non-strictly carnivorous fish (<0.01 to 0.30 mg/kg). Farmed fishes showed significantly lower levels compared to wild fish. Mean Brazilian fish consumption achieves FAO/WHO health recommendation of about two portions of fish per week. However, there is a large difference between fish consumption at urban and rural homes and among Brazilian geographic regions. These differences in consumption impacted estimated methylmercury intake that was higher in the Northern (1.85 μg/kg bw week) and in the Northeastern (0.72 μg/kg bw week) regions and also by rural population (1.08 μg/kg bw week). These values were compared with the toxicological reference dose for neurotoxicity of 1.6 μg/kg bw week.

CONCLUSION

Even though total levels of mercury in fish were lower than Brazilian and international legislations, in the Northern Brazilian region methylmercury intake overpassed the toxicological reference dose for neurotoxicity and in rural areas it achieved 68% of this reference dose.

Environmental and human health risks of arsenic in gold mining areas in the eastern Amazon

Knowledge of arsenic (As) levels in gold (Au) mining areas in the Amazon is critical for determining environmental risks and the health of the local population, mainly because this region has the largest mineral potential in Brazil and one of the largest in the world. The objective of this study was to assess the environmental and human health risks of As in tailings from Au exploration in the eastern Amazon. Samples were collected from soils and tailings from different exploration forms from 25 points, and the total concentration, pollution indexes and human health risk were determined. Concentrations of As were very high in all exploration areas, especially in tailings, whose maximum value reached 10,000 mg kg^-1, far above the investigation value established by the Brazilian National Council of the Environment, characterizing a polluted area with high environmental risk. Exposure based on the daily intake of As demonstrated a high health risk for children and adults, whose non-carcinogenic risk indexes of 17.8, extremely above the acceptable limit (1.0) established by the United States Environmental Protection Agency. High levels of As in reactive fractions in underground, cyanidation, and colluvium mining areas, as well as extremely high gastric and intestinal bioaccessibility were found, suggesting that high levels may be absorbed by the local population. The results show that the study area is highly polluted through Au mining activities, putting the environment and population health at risk, and that there is an urgent need for intervention by the environmental control agencies for remediation.

Biomonitoring of Mercury, Cadmium and Selenium in Fish and the Population of Puerto Nariño, at the Southern Corner of the Colombian Amazon

Heavy metals threaten communities near biodiversity hotspots, as their protein sources come from the environment. This study assessed Hg, Cd, and Se concentrations in fish, as well as the magnitude of exposure and hematological conditions of adult citizens from Puerto Nariño (Colombian Amazon). Among fish samples, greater Hg concentrations were found in higher trophic level species, including Rhaphiodon vulpinus (880 ± 130 ng/g) and Pseudoplatystoma tigrinum (920 ± 87 ng/g). These species presented the highest hazard quotients and lowest Se:Hg molar ratios among those studied, showing their consumption represents a health risk to consumers. Moreover, some samples of Mylossoma duriventre and Prochilodus magdalenae had Cd levels greater than the regulated limit (100 ng/g). The average total Hg (T-Hg) concentrations in human hair and blood were 5.31 µg/g and 13.7 µg/L, respectively. All hair samples exceeded the 1.0 μg/g threshold set by the USEPA, whereas 93% of the volunteers had T-Hg blood levels greater than 5 μg/L, suggesting elevated exposure. The mean Cd level was 3.1 µg/L, with 21% of samples surpassing 5 µg/L, value at which mitigating actions should be taken. Eighty-four percent of participants presented Se deficiencies (<100 μg/L). There was a significant association between fish consumption and T-Hg in hair (ρ = 0.323; p = 0.032) and blood (ρ = 0.381; p = 0.011). In this last matrix, Se correlated with Cd content, whereas lymphocytes were inversely linked to Hg concentrations. The results of this study show that there is  extensive exposure to Hg in fish, the consumption of which may promote detrimental impacts on hematology parameters within the community.

Multi-pathway human exposure risk assessment using Bayesian modeling at the historically largest mercury mining district

The largest mercury (Hg) mining district in the world is located in Almadén (Spain), with well-known environmental impacts in the surrounding ecosystem. However, the impact of mercury on the health of the inhabitants of this area has not been documented accordingly. This study aims to carry out a probabilistic human health risk assessment using Bayesian modeling to estimate the non-carcinogenic risk related to Hg through multiple exposure pathways. Samples of vegetables, wild mushrooms, fish, soil, water, and air were analyzed, and adult residents were randomly surveyed to adjust the risk models to the specific population data. On the one hand, the results for the non-carcinogenic risk based on Hazard Quotient (HQ) showed unacceptable risk levels through ingestion of Hg-contaminated vegetables and fish, with HQ values 20 and 3 times higher, respectively, than the safe exposure threshold of 1 for the 97.5th percentile. On the other hand, ingestion of mushrooms, dermal contact with soil, ingestion of water, dermal contact with water and inhalation of air, were below the safety limit for the 97.5th percentile, and did not represent a risk to the health of residents. In addition, the probabilistic approach was compared with the conservative deterministic approach, and similar results were obtained. This is the first study conducted in Almadén, which clearly reveals the high levels of human health risk to which the population is exposed due to the legacy of two millennia of Hg mining.

Inhalation Exposure to Gaseous and Particulate Bound Mercury Present in the Ambient Air over the Polluted Area of Southern Poland

This study concerns the concentrations of gaseous and particle-bound mercury present in ambient air of two Polish sites, differing in terms of emission structure, and the estimation of inhalation risks related to those Hg species. The measurements of total gaseous mercury (TGM) and PM_2.5-bound mercury (PBM) were performed at an urban station in Zabrze and a rural station in Złoty Potok, in 2014–2015. Both sites are located in Silesia, considered one of the European air pollution hot-spots. TGM was measured on-line (Tekran 2537). PM_2.5 samples were taken with the use of low volume samplers. Hg contents in PM were determined by the CVAAS method following thermal decomposition. The median concentrations of TGM and PBM in Zabrze were 2.48 ng m⁻³ and 37.87 pg m⁻³, respectively; meanwhile in Zloty Potok, these were 1.69 ng m⁻³ and 27.82 pg m⁻³, respectively. Clearly, seasonal variability of TGM and PBM concentrations were observed, reflecting the importance of Hg and PM emissions from coal combustion for power and heating purposes. Health risk assessment was performed using a deterministic approach by the most conservative exposure scenario. The obtained HQ ratios and the cumulative HI indexes were below the limit value (<1). This means an unlikely health hazard due mercury inhalation.

Mercury in fish marketed in the Amazon Triple Frontier and Health Risk Assessment

Fish has great socioeconomic, cultural, and nutritional importance for Amazonian populations. Despite all health benefits, fish can accumulate great amounts of mercury (Hg). The entry of Hg in aquatic trophic chains is an issue of concern to animal and human health. Higher risks of human exposure are strongly related to fish consumption. Upper Solimões population has one of the highest fish consumption rates of the Amazon. This study aimed to access the concentration of total Hg (THg) in muscle, liver, and gills of 17 species of fishes marketed in the Upper Solimões Region and Health Risk Assessment. Higher concentrations were observed in Carnivores/Piscivores. The highest THg concentration was found in liver of Cichla ocellaris (4.549 μg/g) and the lowest in gills of Hoplosternum littorale (0.002 μg/g). Most species had higher THg concentrations in muscle>liver>gills, in the Ebb period, and liver>muscle>gills, in the Flood period. Hoplias malabaricus, Pseudoplatystoma fasciatum, Plagioscion squamosissimus, Ageneiosus inermis, and C. ocellaris presented average THg concentrations above the safe limit stablished by WHO. THg levels in C. ocellaris, H. malabaricus, P. squamosissimus, P. fasciatum, and Semaprochilodus insignis were higher than those found in fish of heavily impacted areas. Signs of bioaccumulation and biomagnifications of Hg can already be observed in this region. The Western Amazon Region urgently needs government actions to inhibit Hg release in aquatic ecosystems and to advise this population on the safe amount of fish to be eaten according to species and period of the year.

Mercury contamination levels in the bioindicator piscivorous fish Hoplias aïmara in French Guiana rivers: mapping for risk assessment

In French Guiana, native populations present high level of mercury contamination, which has been linked to the consumption of contaminated fishes. The goal of this study is to undertake a cartography of mercury contamination levels in fishes from the six main Guiana rivers. The selected species for this study is the ubiquitous piscivorous fish Hoplias aimara. A total number of 575 fishes from 134 discrete fishing sites are regrouped into 51 river sectors. Results from this study permits to rank the six main Guiana rivers by their mean level of contamination: Oyapock (0.548 mg kg^-1), Comté (0.624 mg kg^-1), Maroni (0.671 mg kg^-1), Approuague (0.684 mg kg^-1), Mana (0.675 mg kg^-1), and Sinnamary (1.025 mg kg^-1). The contamination is however not spatially homogenous along each river, and a map of the different levels of mercury contamination in fishes is provided. Sectors of low mean Hg contamination are observed both upstream (0.471 mg kg^-1) and downstream (0.424 mg kg^-1), corresponding to areas without any influence of gold mining activities and areas under the influence of estuarine dilution, respectively. Anoxia and gold mining activities are found to be the two main factors responsible for the high mercury concentration in fish muscles. While mean levels of mercury contaminations are higher in anoxia areas (1.029 mg kg^-1), contaminations induced by gold mining activities (0.717 mg kg^-1) present the most harmful consequences to human populations. No significant differences in Hg concentrations are observed between 2005 and 2014 for neither a pristine nor a gold mining area, while Hg concentration differences are observed between former (0.550 mg kg^-1) and current gold mining sites (0.717 mg kg^-1).

Sensor-as-a-Service: Convergence of Sensor Analytic Point Solutions (SNAPS) and Pay-A-Penny-Per-Use (PAPPU) Paradigm as a Catalyst for Democratization of Healthcare in Underserved Communities

In this manuscript, we discuss relevant socioeconomic factors for developing and implementing sensor analytic point solutions (SNAPS) as point-of-care tools to serve impoverished communities. The distinct economic, environmental, cultural, and ethical paradigms that affect economically disadvantaged users add complexity to the process of technology development and deployment beyond the science and engineering issues. We begin by contextualizing the environmental burden of disease in select low-income regions around the world, including environmental hazards at work, home, and the broader community environment, where SNAPS may be helpful in the prevention and mitigation of human exposure to harmful biological vectors and chemical agents. We offer examples of SNAPS designed for economically disadvantaged users, specifically for supporting decision-making in cases of tuberculosis (TB) infection and mercury exposure. We follow-up by discussing the economic challenges that are involved in the phased implementation of diagnostic tools in low-income markets and describe a micropayment-based systems-as-a-service approach (pay-a-penny-per-use-PAPPU), which may be catalytic for the adoption of low-end, low-margin, low-research, and the development SNAPS. Finally, we provide some insights into the social and ethical considerations for the assimilation of SNAPS to improve health outcomes in marginalized communities.

Mercury exposure assessment in indigenous communities from Tarapaca village, Cotuhe and Putumayo Rivers, Colombian Amazon

Mercury (Hg) is a complex and multifaceted global pollutant. Artisanal and small-scale gold mining activities are largely responsible for Hg contamination in developing countries, in many cases impacting areas of high biodiversity such as the Amazon. The aim of the study was to establish Hg exposure in indigenous citizens from the Tarapaca village, Cotuhe and Putumayo Rivers, at the Colombian Amazon. Total Hg (T-Hg) concentrations were measured employing a DMA-80 Hg analyzer. For that purpose, 190 hair samples were taken from volunteers living in different communities of Tarapaca. The overall mean T-Hg level for all samples was 10.6 ± 0.4 μg/g, with values ranging from 0.61 to 31.1 μg/g. The mean T-Hg level decreased in the order Puerto Huila > Puerto Ticuna > Ventura > Nueva Union > Buenos Aires > Santa Lucia > Puerto Nuevo > Caña Brava > Pupuña. Based on recommendations from the United States Environmental Protection Agency (US EPA), 99.5% of the samples exceeded the maximum level of 1.0 μg/g. Hg content in human hair was significantly associated with fish consumption (ρ = 0.253; p < 0.001). According to the health survey, at least 24.7% of the volunteers manifested some signs and symptoms of Hg poisoning. In short, these data support the extensive Hg exposure in the environment of the Colombian Amazon, a process that could be impacting the quality of life of its vulnerable indigenous groups. Immediate actions must be taken by competent authorities to protect these communities from Hg poisoning.

Oxidative Damage in Human Periodontal Ligament Fibroblast (hPLF) after Methylmercury Exposure

Human exposure to mercury (Hg) is primary associated with its organic form, methylmercury (MeHg), through the ingestion of contaminated seafood. However, Hg contamination is also positively correlated with the number of dental restorations, total surface of amalgam, and organic mercury concentration in the saliva. Among the cells existing in the oral cavity, human periodontal ligament fibroblast (hPLF) cells are important cells responsible for the production of matrix and extracellular collagen, besides sustentation, renewal, repair, and tissue regeneration. In this way, the present study is aimed at investigating the potential oxidative effects caused by MeHg on hPLF. Firstly, we analyzed the cytotoxic effects of MeHg (general metabolism status, cell viability, and mercury accumulation) followed by the parameters related to oxidative stress (total antioxidant capacity, GSH levels, and DNA damage). Our results demonstrated that MeHg toxicity increased in accordance with the rise of MeHg concentration in the exposure solutions (1-7 μM) causing 100% of cell death at 7 μM MeHg exposure. The general metabolism status was firstly affected by 2 μM MeHg exposure (43.8 ± 1.7%), while a significant decrease of cell viability has arisen significantly only at 3 μM MeHg exposure (68.7 ± 1.4%). The ratio among these two analyses (named fold change) demonstrated viable hPLF with compromised cellular machinery along with the range of MeHg exposure. Subsequently, two distinct MeHg concentrations (0.3 and 3 μM) were chosen based on LC50 value (4.2 μM). hPLF exposed to these two MeHg concentrations showed an intracellular Hg accumulation as a linear-type saturation curve indicating that metal accumulated diffusively in the cells, typical for metal organic forms such as methyl. The levels of total GSH decreased 50% at exposure to 3 μM MeHg when compared to control. Finally, no alteration in the DNA integrity was observed at 0.3 μM MeHg exposure, but 3 μM MeHg caused significant damage. In conclusion, it was observed that MeHg exposure affected the general metabolism status of hPLF with no necessary decrease on the cell death. Additionally, although the oxidative imbalance in the hPLF was confirmed only at 3 μM MeHg through the increase of total GSH level and DNA damage, the lower concentration of MeHg used (0.3 μM) requires attention since the intracellular mercury accumulation may be toxic at chronic exposures.

Mercury levels in human hair in South India: baseline, artisanal goldsmiths and coal-fired power plants

India is a major emitter of mercury to the environment, mainly due to emissions from coal-fired power plants. Consumption of fish and rice, two important pathways for human exposure to mercury, is particularly high in South India. Here, we report concentrations of total mercury in hair (THg_hair) in 668 participants from South India. Three cities were covered: (i) a city on the east coast with four active coal-fired thermal power plants (Nellore), (ii) a city on the west coast with no major mercury source (Vasco da Gama), and (iii) a metropolitan city in the interior with no major mercury source (Hyderabad). Geometric mean of THg_hair of the entire study population is 0.14 µg/g (95% confidence interval, CI: 0.13-0.15 µg/g). Significant predictor variables are age, fish consumption, and occupations such as dental studies, subsistence fishing, and artisanal goldsmithing (which is different from artisanal scale gold mining). Our results support the hypothesis that people living in a city with active coal-fired power plants may have higher THg_hair than those in cities with no major mercury source.

SCARECROW promoter-driven expression of a bacterial mercury transporter MerC in root endodermal cells enhances mercury accumulation in Arabidopsis shoots

Mercury accumulation in Arabidopsis shoots is accelerated by endodermis specific expression of fusion proteins of a bacterial mercury transporter MerC and a plant SNARE SYP121 under control of SCARECROW promoter. We previously demonstrated that the CaMV 35S RNA promoter (p35S)-driven ubiquitous expression of a bacterial mercury transporter MerC, fused with SYP121, an Arabidopsis SNARE protein increases mercury accumulation of Arabidopsis. To establish an improved fine-tuned mercury transport system in plants for phytoremediation, the present study generated and characterized transgenic Arabidopsis plants expressing MerC-SYP121 specifically in the root endodermis, which is a crucial cell type for root element uptake. We generated four independent transgenic Arabidopsis lines expressing a transgene encoding mCherry-MerC-SYP121 under the control of the endodermis-specific SCARECROW promoter (hereafter pSCR lines). Quantitative real-time PCR analysis showed that expression levels of the transgene in roots of the pSCR lines were 3-23% of the p35S driven-overexpressing line. Confocal microscopy analysis showed that mCherry-MerC-SYP121 was dominantly expressed in the endodermis of the meristematic zone as well as in the mature zone of the pSCR roots. Mercury accumulation in shoots of the pSCR lines exposed to inorganic mercury was overall higher than the wild-type and comparable to the p35S over-expressing line. These results suggest that endodermis-specific expression of the MerC-SYP121 fusion proteins in plant roots sufficiently enhances mercury uptake and accumulation into shoots, which would be an ideal phenotype for phytoremediation of mercury-contaminated environments.

Mapping the Evolution of Mercury (Hg) Research in the Amazon (1991⁻2017): A Scientometric Analysis

Because the Amazon rain forest is ecologically relevant on a global scale, we applied scientometric techniques to integrate studies dealing with mercury research in this unique ecosystem between 1991 and 2017. Using a combination of co-authorship and co-citation analyses, keyword mapping and overlay visualization of topics in the field, this article identified three major areas in the 26-year period of mercury research: (1) human exposure to mercury (artisanal small-scale gold mining-ASGM) and methylmercury through fish consumption, and their respective risks for human health; (2) mercury accumulation in the environment and its relation to ASGM and atmospheric concentration; and (3) mercury geochemistry and its presence in soils, sediments, and water. The paper also identified the leading institutions related to the published research and respective influential scholars in the context of this study. Overall, the analyses revealed patterns of convergence and divergence between authors, specialization, and interdisciplinary engagement in mercury investigation, thus highlighting strengths and weaknesses of research topics in the field. This scientometric approach could be a useful tool to monitor/assess the implementation of the Minamata Convention.

Mercury at environmental relevant levels affects spermatozoa function and fertility capacity in bovine sperm

Over the last several years human sperm quality was found to be significantly reduced and the role environmental contaminants play in this phenomenon remain to be determined. Mercury (Hg) is one of the most widespread contaminants; however the correlation between metal exposure and adverse consequences on human and animals fertility are not completely established. The aim of this study was to determine the effects of direct exposure to inorganic Hg on male gametes using spermatozoa (bovine sperm) which characteristically resemble human sperm. Sperm were divided and incubated for 0.5, 1 or 2 h at low levels of Hg: i) Control: without exposure; ii) Hg8 nM: mercury chloride (HgCl₂) at 8 nM and iii) Hg8 μM: HgCl₂ at 8 μM. Sperm kinetics, morphology, sperm membrane integrity, and in vitro fertilization were assessed. In addition the levels of reactive oxygen species (ROS), lipid peroxidation and total antioxidant capacity were measured. Hg exposure for 2 h impaired sperm morphology and membrane integrity as well as kinetic parameters including curvilinear velocity and straight-line velocity, which are needed for fertilization as evidenced by the reduced fertilization rate in 8 μM Hg-treated gametes. Hg enhanced oxidative stress in male sperm as reflected by elevated levels of ROS and lipid peroxidation and decreased antioxidant capacity. Data demonstrated that low levels of Hg when incubated with spermatozoa are sufficient to increase oxidative stress, adversely affect sperm quality parameters, subsequently impairing sperm fertility capacity.

Assessment of Total Mercury in Hair, Urine and Fingernails of Small-Scale Gold Miners in the Amansie West District, Ghana

BACKGROUND

Mercury (Hg) is a heavy metal that can cause several adverse health effects based on its form (organic, inorganic or elemental), duration and pathway of exposure. Measurement of mercury present in human biological media is often used to assess human exposure to mercury at mining sites.

OBJECTIVES

The aim of the present study was to measure the concentrations of total mercury in urine, hair, and fingernails of miners and inhabitants of Amansie West District, Ghana.

METHODS

Concentrations of total mercury were measured in sixty-eight miners and twelve non-miners in the study area using cold vapor atomic absorption spectrophotometry with an automatic mercury analyzer (HG 5000).

RESULTS

Total mercury in nails and hair of smelter miners was 3.32 ± 0.36 and 6.59 ± 0.01 μg/g, respectively. Total mercury concentrations in hair samples obtained from smelter miners were above the 1 μg/g guideline set by the United States Environmental Protection Agency (USEPA). Moreover, the total mercury concentration in urine samples was 6.97 ± 0.06 μg/L, far below the >25 μg/L level considered to be a high level of mercury contamination. The total mercury accrued by the individuals was not dependent on age, but was positively associated with duration of stay.

CONCLUSIONS

Based on the total mercury (THg) levels analyzed in the biological media, artisanal gold mining activities in Amansie West District are on the increase with a potential risk of developing chronic effects. However, the majority of the population, particularly those engaged in artisanal small-scale gold mining, are unmindful of the hazards posed by the use of mercury in mining operations. The results showed that THg in urine, hair, and fingernails more efficiently distinguished mercury exposure in people close to mining and Hg pollution sources than in people living far from the mining sites. Further education on cleaner artisanal gold mining processes could help to minimize the impact of mercury use and exposure on human health and the environment.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

This study was approved by the Ghana Environmental Protection Agency and the Ministry of Local Government and Rural Development in Manso Nkwanta.

COMPETING INTERESTS

The authors declare no competing financial interests.

Quantifying the impacts of artisanal gold mining on a tropical river system using mercury isotopes

In some locations, artisanal and small-scale gold-mining (ASGM) represents a significant source of anthropogenic Hg to freshwater environments. The Hg released from ASGM can contaminate aquatic fauna and pose health risks to downstream populations. Total Hg (THg) concentrations, speciation, and isotopic compositions were analyzed in water, suspended particulate matter, soil, and bottom sediment samples from pristine areas and in places of active and legacy gold mining along the Oyapock River (French Guiana) and its tributaries. Mass-independent fractionation (MIF) of even Hg isotopes in top soils (Δ²⁰⁰Hg = -0.06 ± 0.02‰, n = 10) implied the uptake of gaseous Hg(0) by plants, rather than wet deposition, as the primary Hg source. Odd isotope MIF was lower in deep soils (Δ¹⁹⁹Hg = -0.75 ± 0.03‰, n = 7) than in top soils (Δ¹⁹⁹Hg = -0.55 ± 0.15‰, n = 3). This variation could be attributed to differences between the isotopic signatures of modern and pre-industrial atmospheric Hg. Combining a Hg-isotope binary mixing model with a multiple linear regression based on physico-chemical parameters measured in the sediment samples, we determined that active mined creek sediments are contaminated by ASGM activities, with up to 78% of THg being anthropogenic. Of this anthropogenic Hg, more than half (66-74%) originates from liquid Hg(0) that is released during ASGM. The remaining anthropogenic Hg comes from the ASGM-driven erosion of Hg-rich soils into the river. The isotope signatures of anthropogenic Hg in bottom sediments were no longer traceable in formerly mined rivers and creeks.