Small-scale Gold Mining Communities Research Articles

The politics of toxicity governance in Colombian gold mining

The most recent Global Mercury Assessment estimates that human-made mercury releases are approximately 2,220 tons per year and that a significant source is artisanal and small-scale gold mining (UNEP 2019). The ubiquity of mercury and its negative effects on human health and the environment have given rise to mercury governance schemes at different administrative scales, and Colombia banned the substance from mining in 2018. This ban is depicted as protecting the environment and human health from toxic mercury, but it has been highly contested within artisanal and small-scale gold mining communities. This contribution will show that the contestations of the mercury ban are intimately related to the deeply political and representational qualities of mercury held by artisanal and small-scale gold producers. Hence, mercury governance has become an important dimension of a broader negotiation over the place of historically marginalized and increasingly criminalized artisanal and small-scale gold producers in contemporary extractivism. The combination of legal framework analysis with semi-structured interviews and ethnographic work in two gold mining towns in Colombia provides a more nuanced and politicized understanding of local opposition to mercury governance that moves beyond simplistic assumptions about mercury users and their contaminated bodies. 

Participatory assessment of pollution and health risk in artisanal and small-scale gold mining communities in Colombia

The predominantly Afro-descendant communities of Yolombó and La Toma depend on the region's rich natural resources through livelihoods such as farming, fishing, and artisanal and small-scale gold mining (ASGM). Previous studies of the region have identified elevated levels of mercury in several surface and groundwater sites. Furthermore, recent regional studies have identified human health risks associated with mercury exposure through hazard quotient (HQ) modeling and global sensitivity and uncertainty analysis (GSUA). However, there has yet to be a comprehensive analysis of water pollution involving different metals and metalloids potentially present in ASGM-influenced areas to estimate the associated environmental and human health impacts. In this study, we employed a participatory methodology to identify sources of exposure in Colombian ASGM communities through surveys, consumption diaries, and interviews. We then screened for relevant metals and metalloids through groundwater analysis using inductively coupled plasma optical emission spectroscopy (ICP-OES) and cold vapor atomic absorption spectrometry (CV-AAS). Furthermore, we calculated water pollution indices, including heavy metal pollution index (HPI), degree of contamination (Cd), heavy metal toxicity load (HMTL) and heavy metal evaluation index (HEI). Finally, we quantified human health risks related to groundwater consumption through the HQ and hazard index (HI). Although the groundwater assessed in this study generally meets United States and Colombian regulatory standards, heightened Fe, Mn, and Al levels were observed. The pollution indices generally agreed that three of the sites tested showed medium to high pollution levels. The HI showed that the combined effect of all metals tested did not substantiate risk for most participants. However, the HI of one participant, a child, exceeded the 1.00 threshold. Furthermore, the presence of Pb, despite meeting regulatory limits, necessitates further scrutiny due to its substantial impact on pollution and human health hazard indices.

Education and equipment distribution lead to increased mercury knowledge and retort use in artisanal and small-scale gold mining communities in Senegal

Artisanal and small-scale gold mining is an important livelihood, but also the largest contributor to anthropogenic mercury emissions globally. Two key persistent challenges in reducing mercury use in artisanal and small-scale gold mining communities are effective educational interventions and accessibility to improved technologies. This study evaluates the efficacy of education and equipment distribution interventions to reduce mercury use in artisanal gold mining in Senegalese mining communities. We analyzed the effects of education and retort (mercury-capture devices) distribution through pre- and post-intervention surveys in nine Senegalese mining communities, divided into control, education-only, and education + retort distribution. Educational sessions were conducted in local languages using simple graphics by trusted community members. Retorts were constructed by local metalworkers using locally available materials. The combination of education and retort distribution increased knowledge about the efficacy of retorts and dangers of mercury (94% post-intervention). The combination also increased retort use, from 3% to 64% post-intervention. Retort use in the other two groups also marginally increased. The increased knowledge and retort use observed in control villages suggests a potential social overflow effect of the intervention, extending beyond the locations in which they occurred. Our results indicate that the graphics-based and community-oriented educational approach accompanied by increased access to retorts provides a strong foundation for reducing mercury emissions and exposure to artisanal and small-scale gold mining communities.

Determination of methylmercury and inorganic mercury in human hair samples of individuals from Colombian gold mining regions by double spiking isotope dilution and GC-ICP-MS

With the aim to distinguish between routes of exposition to mercury (Hg) in artisanal and small-scale gold mining (ASGM) communities and to distinguish between Hg contamination sources, Hg species composition should be performed in human biomarkers. In this work, Hg species-specific determination were determined in human hair samples (N = 96), mostly non-directly occupied in ASGM tasks, from the six most relevant gold mining Colombian regions. Therefore, MeHg, Hg(II) and THg concentrations were simultaneously determined by double spiking species-specific isotope dilution mass spectrometry (IDMS) and GC-ICP-MS. Only 16.67% of participants were involved at some point in AGSM works and fish consumption ranged from 3 to 7 times/week, which is between medium and high intake levels. The median concentration of THg obtained from all samples is higher than the reference dose weekly acceptable of MeHg intake established by the EPA (1 ppm), whereas a 25% were more than 4 times higher than the WHO level (2.2 μg Hg g−1). Median THg value of individuals consuming fish 5–7 times per week was significantly higher (p < 0.05) than those of the other consuming groups (12.5 μg Hg g−1). Most of the samples presented a % of MeHg relative to THg higher than 80%. The average % of Hg(II)/THg was 11% and only 10 individuals presented a Hg(II) content over 30%. No significant differences (p > 0.05) were found when the amount of Hg(II) was compared between people involved in AGSM task and people not involved. Interestingly, significant differences among the evaluated groups where found when the percentage of the Hg(II)/THg ratio of these groups were compared. In fact, people involved in AGSM tasks showed 1.7 times higher Hg(II)/THg vs. inhabitants uninvolved. This suggest that Hg(II) determination by IDMS-GC-ICP-MS could be a good proxy for evaluating Hg(II) adsorption by direct exposure to mercury vapors onto hair.

Adverse Health Effects and Mercury Exposure in a Colombian Artisanal and Small-Scale Gold Mining Community.

The aim of this study was, first of all, to associate the mercury (Hg) concentrations and respiratory functions of the gold miners in the artisanal small-scale gold mining (ASGM) environment in San Martín de Loba, Colombia. We carried out a cross-sectional study using a survey whereby we collected basic demographic information, occupational medical history, and applied two validated questionnaires (Q16 and SF36). We measured Hg levels in all volunteers using direct thermal decomposition-atomic absorption spectrometry. Univariate and bivariate statistical analyses were carried out for all variables, performing logistic regression to assess the effect of ASGM on health outcomes. Volunteers enrolled (n = 124) were between the ages of 20 and 84 years (84% miners and 79% males). No changes were found in the systolic blood pressure, diastolic blood pressure, and heart rate from the ASGM miners, in crude and adjusted statistical analyses. ASGM miners increased 8.91 (95% confidence interval, 1.55-95.70) times the risk of having these than of having neurotoxic effects. Concentrations of total whole blood mercury (T-Hg) in all participants ranged from 0.6 to 82.5 with a median of 6.0 μg/L. Miners had higher T-Hg concentrations than non-miners (p-value = 0.011). Normal and abnormal respiratory spirometry patterns showed significant differences with the physical role and physical function of quality-of-life scales (the (p-value was 0.012 and 0.004, respectively). The spirometry test was carried out in 87 male miners, with 25% of these miners reporting abnormalities. Out of these, 73% presented a restrictive spirometry pattern, and 27%, an obstructive spirometry pattern. The ASGM population had higher Hg concentrations and worse neurotoxic symptomatology than non-miners of the same community.

Perceptions and realities of mercury contamination in a Peruvian artisanal and small-scale gold mining (ASGM) community

Artisanal and small-scale gold mining (ASGM) is the leading global source of mercury pollution. Efforts to reduce or eliminate mercury use in ASGM have produced limited results, in part because they do not engage the complex socio-technical nature of mercury issues in ASGM. The paper takes a multidisciplinary approach to understand the mercury issue with a socio-technical lens, pairing sampling of mercury in soils with surveys of miners' and residents' perceptions of mercury pollution and its dispersion. The research was conducted in Secocha, an ASGM boomtown in southern Peru. Mercury levels in soils exceeded relevant standards in both industrial zones (average of 72.6 mg/kg, versus the Peruvian standard of 24 mg/kg) and residential/urban zones (average of 9.5 mg/kg, versus the Peruvian standard of 6.6 mg/kg). Mercury levels were highest where processing and gold buying activity were concentrated. Surveys revealed that miners and residents correctly assumed mercury pollution to be highest in those areas. However, respondents seemed to underestimate the extent of mercury pollution in other parts of town, and many believed that only those who handle mercury directly were affected by it. Respondents also placed low priority on reducing mercury pollution. Miners' and residents’ partial knowledge about mercury contamination and the low priority accorded to the issue suggest that mercury reduction efforts would likely be met with indifference and potentially resistance.

Available Legal Regime and The Use of Mercury for Small-Scale Gold Mining in Ghana

The aim of this study was to examine the effects of mercury (Hg) and available laws to regulate its use in the Artisanal and Small-Scale Gold Mining (ASGM) Community in Ghana. Research shows that the use of Hg in the ASGM causes damage to the cognitive and neurological function of the miners, as well as to the physical and mental disabilities to children in the ASGM communities. Furthermore, number of publications also shows that the use of Hg causes significant damage to water bodies and the environment in most mining communities. Additionally, in an attempt to protect the environment from these high levels of Hg in these mining sites and beyond, has led to some conflict and military intervention. Even though, Ghana has adequate laws to regulate Hg use by reducing and where feasible eliminate the use of Hg for small-scale mining. However, due to some legal limitations to the current situation there is the need to amend some of these laws to help address these challenges. In addition, certain policies, technological and educational initiatives taken to address the use of Hg in our environment, have proven largely ineffective. The results of this study shows that the implementation of mining regulation without careful analysis of mine community dynamics, the organization of activities, operators’ needs and local geological conditions has resulted in some challenges. However, significant improvements can only be achieved in this area if the state and the organs of government tackle the illegal mining “galamsey” menace; introducing cost-effective techniques for the reduction of the use of Hg in mining; effective government sponsored participatory training exercises as mechanisms for communicating information about appropriate technologies and the environment; and strengthening compliance and enforcement of existing laws. In conclusion there is the urgent need to properly regulate the use of Hg in mining communities in Ghana.

Correction to: Emerging mercury mitigation solutions for artisanal small-scale gold mining communities evaluated through a multicriteria decision analysis approach

Correction to: Emerging mercury mitigation solutions for artisanal small-scale gold mining communities evaluated through a multicriteria decision analysis approach

Transdisciplinary Communities of Practice to Resolve Health Problems in Southeast Asian Artisanal and Small-Scale Gold Mining Communities.

Artisanal and small-scale gold mining (ASGM) has been a major part of people’s livelihood in the rural areas of many developing countries, including those in Southeast Asia (SEA). Nevertheless, because of the use of mercury, ASGM activities have significant local and global adverse impacts on the environment and ASGM community health. Although there have been many monodisciplinary projects by academic researchers and governments to solve the environmental and health problems in SEA ASGM communities, they have not been sufficient to solve the complex socioeconomic problems. This review first outlines the nature of the SEA ASGM activities and the consequent environmental, community health, and socioeconomic problems and then introduces an approach using transdisciplinary communities of practice that involves both academic and nonacademic participants to relieve these wicked ASGM problems and to improve the environmental governance and community health in ASGM communities in SEA.

Examining Preference Heterogeneity in Best-Worst Scaling: Case of Preferences for Job Opportunities in Artisanal Small-Scale Gold Mining (ASGM) Communities in Indonesia

This research empirically examines the preferences for job-related attributes among rural villagers living close to artisanal and small-scale gold mining (ASGM) in Indonesia. Based on hypothetical scenarios in which a private company collaborates with the local government to establish a food processing industry in these villages, a questionnaire survey designed with best–worst scaling (BWS) was administered to households to determine their preferences. Additionally, the heterogeneity among the villagers was examined by applying a latent class logit (LCL) model. The main household survey was conducted in 2019 in Bone Bolango Regency, Gorontalo Province. The estimation results revealed that villagers are separated into four classes, and each class has different and unique preferences. Creating more job opportunities for society is a highly evaluated attribute; however, the preference for skill acquisition differs among groups. The results indicate that accounting for heterogeneous preferences regarding job opportunities is helpful to delink dependency on ASGM and health hazards and improve the livelihoods of rural villagers. The study yields key information to substantially reduce environmental and health hazards in the poverty-plagued ASGM community by facilitating job opportunities in Indonesia.

Efficacy of Hair Total Mercury Content as a Biomarker of Methylmercury Exposure to Communities in the Area of Artisanal and Small-Scale Gold Mining in Madre de Dios, Peru

Total mercury content (THg) in hair is an accepted biomarker for chronic dietary methylmercury (MeHg) exposure. In artisanal and small-scale gold mining (ASGM) communities, the validity of this biomarker is questioned because of the potential for contamination from inorganic mercury. As mining communities may have both inorganic and organic mercury exposures, the efficacy of the hair-THg biomarker needs to be evaluated, particularly as nations begin population exposure assessments under their commitments to the Minamata Convention. We sought to validate the efficacy of hair THg for public health monitoring of MeHg exposures for populations living in ASGM communities. We quantified both THg and MeHg contents in hair from a representative subset of participants (N = 287) in a large, population-level mercury exposure assessment in the ASGM region in Madre de Dios (MDD), Peru. We compared population MeHg-THg correlations and %MeHg values with demographic variables including community location, sex, occupation, and nativity. We observed that hair MeHg-THg correlations were high (r > 0.7) for all communities, regardless of location or nativity. Specifically, for individuals within ASGM communities, 81% (121 of 150 total) had hair THg predominantly in the form of MeHg (i.e., >66% of THg) and reflective of dietary exposure to mercury. Furthermore, for individuals with hair THg exceeding the U.S. EPA threshold (1.0 μg/g), 88 out of 106 (83%) had MeHg as the predominant form. As a result, had urine THg solely been used for mercury exposure monitoring, approximately 59% of the ASGM population would have been misclassified as having low mercury exposure. Our results support the use of hair THg for monitoring of MeHg exposure of populations in ASGM settings where alternative biomarkers of MeHg exposure are not feasible.

Transdisciplinary Online Health Assessment of an Artisanal and Small-Scale Gold Mining Community during the COVID-19 Pandemic in the Mandalay Region of Myanmar

Artisanal and small-scale gold mining (ASGM) has a known negative effect on the community’s health; therefore, assessment to monitor community health is essential to detect any issues and enable early treatment. Because ASGM-related health issues are complex and cannot be addressed effectively with a traditional one-time health assessment alone, both long-term and regular health assessments using a transdisciplinary approach should be considered. In response to this need, we designed an online health assessment tool as a reference for a future long-term health assessment system. An online video interview was conducted with 54 respondents living in the ASGM area of Chaung Gyi Village, Thabeikkyin Township, Mandalay Region, Myanmar, via a social networking service application. The tool was used to evaluate community health during the coronavirus 2019 pandemic, including mercury intoxication symptoms, mining-related diseases, and other diseases. Results show that persons working in mining versus non-mining occupations had a greater prevalence of pulmonary diseases, such as pulmonary tuberculosis, silicosis, and bronchial asthma, in addition to malaria. Based on these findings, online health assessment using a transdisciplinary approach can be recommended as an effective tool for sustainable and long-term health assessment of ASGM-related disease and should be performed regularly following physical health surveys.

Socio-environmental perceptions and barriers to conservation engagement among artisanal small-scale gold mining communities in Southeastern Peru

Artisanal small-scale gold mining (ASGM) poses threats to biodiversity and to the health and well-being of human communities. However, ASGM also economically supports several populations from lower social-economic backgrounds, especially in the Global South. In Madre de Dios (MDD), Peru, ASGM is the most significant economic activity, involving several stakeholders form different levels of governance. To protect this area’s forests and aquatic systems from further degradation, it is necessary to understand the socio-economic background and the impediments to mining formalization, as well as the local perceptions and willingness to engage in conservation. In this study, we aimed to establish the drivers of and barriers to participation in environmental conservation among communities in MDD, which economically rely on ASGM. Using a mixed method approach, we surveyed 85 households in six communities in the MDD gold corridor. Half of participants were cognizant of the effects of ASGM and concerned about deforestation and local decreases in fish and wildlife abundance, declaring willingness to take part in environmental conservation. Native participants in particular expressed concern about land degradation and the action of immigrants. However, several participants reported feeling alienated by government institutions and raised doubts about the intentions of non-governmental conservation organizations, and the purpose of protected areas. Participants in general felt that ASGM-related policies were not realistic and bureaucratic barriers were raised to prevent formalization. Our findings suggest that current policies and communication strategies may hinder efforts to transform relatively prevalent pro-environmental attitudes into matching behaviors, including participation in conservation initiatives. To achieve this goal, more efficient communication and more active involvement of local stakeholders in mining governance and conservation planning are necessary.

Integrating scientific and local knowledge into pollution remediation planning: An iterative conceptual site model framework

Pollution remediation decisions in developing communities are often made with limited technical data and stakeholder engagement. Local knowledge of contamination is oftentimes neglected, resulting in efforts that fail to align with community objectives. In this work, we propose a new approach for incorporating local knowledge on contamination into remediation efforts, resulting in a community-informed conceptual site model framework for pollution remediation. This framework uses qualitative and quantitative social science methods to develop a holistic view of contamination as defined by the community, pairing social knowledge with existing technical information about a site. An example of the application of this framework is provided from a field study conducted in a mercury-contaminated artisanal and small-scale gold mining community in Andes, Colombia. We conducted qualitative unstructured and semi-structured interviews and surveys to elicit local knowledge on mercury contamination. We combined this stakeholder input with limited scientific published literature on mercury contamination in artisanal mining communities to develop different conceptual site models that vary based on the level and type of stakeholder input. Our findings demonstrate how local knowledge on contamination varies due to contextual factors within the community, revealed through the engagement. This work also demonstrates how the new framework can be utilized by environmental practitioners to define the needs, wants, and priorities of stakeholder groups throughout a remediation project, ensuring maximum participation in solution development.

CHALLENGES IN COMBATING CHILD LABOUR IN SMALL-SCALE GOLD MINING COMMUNITIES IN SHINYANGA REGION, TANZANIA

Combating child labour in Tanzania is a challenging endeavour especially in small-scale gold mining communities. Studies on child labour in Tanzania indicate that the government in partnership with international actors has undertaken several intervention actions to control and eliminate child labour in the country. Yet, child labour continues to be dominant in virtually all economic sectors including small-scale gold mining for reasons not sufficiently known. This research sets out to explore the challenges that face anti-child labour actors in their efforts to control and reduce child labour in Kahama district in Shinyanga region. The study uses a qualitative methodology in order to gain an in-depth insight of the context, cultural realities, community members’ views and experiences relating to child labour in small-scale gold mining communities. A sample size of 38 participants was drawn from among regional and district government officials, non-governmental organization (NGO) workers and community-based organization (CBO) activists responsible for combating child labour, small-scale gold miners, parents and children in Shinyanga region. Data was collected through in-depth interviews, focus group discussions and documents review. Findings revealed seven challenges facing anti-child labour actors in their efforts to combat child labour in small-scale gold mining communities all arising from within the household, local community and government contexts. The study recommends that the government, policy makers and other stakeholders should develop policy interventions that effectively address these challenges in order to eradicate child labour in small-scale gold mining communities in the country. Keywords: Child Labour, Small-Scale Gold Mining, Anti-Child Labour Actors, Challenges.

Emerging mercury mitigation solutions for artisanal small-scale gold mining communities evaluated through a multicriteria decision analysis approach

Over 15 million people are involved in artisanal small-scale gold mining (ASGM) globally. Often, ASGM includes smelters that use mercury to extract gold. If mishandled, these actions may cause adverse health effects for smelters and their surrounding communities. There are multiple tools to reduce health risks while maintaining a sustainable economic profit, but each method has trade-offs, such as cost, efficiency, and potential health impacts that are not widely understood. Multicriteria decision analysis (MCDA) is a powerful tool in assessing multiple perspectives and factors that affect stakeholder decisions and can be used to inform smelters and community members on reducing exposure to mercury. Here, MCDA was used to determine the ranks of alternatives to reduce exposure to mercury based on socio-economic, ecological, and human health criteria. Stochastic processes were used to evaluate 12 alternatives, including mitigation strategies (i.e., chelation therapy techniques, retorts, water filters) as well as mercury-free mining substitutes. In this model, the borax method ranked first 72% of the time, followed by the gravity method (19%), a multicapture system retort (7%), and low-cost retorts (≤ 1%). While MCDA is an excellent tool, results tend to be generalized across a heterogenous landscape. More localized factors such as incorrect soil chemistry could cause performance challenges for options like mercury-free mining substitutes. To aid more localized decision-making, a decision tree model was developed to aid stakeholders to explore which alternatives are suitable based on context-specific factors using “Take-the-best” decision heuristics. This work can assist researchers and stakeholders involved with ASGM to identify which options are scalable for their region as well as to mitigate adverse effects of exposure to mercury.

Mercury methylation in cyanide influenced river sediments: A comparative study in Southwestern Ghana.

Studies on the influence of CN on Hg methylation rates in aquatic systems draining gold mining (artisanal and small-scale) communities in Africa are rare. The study assessed the influence of CN on Hg methylation in aquatic sediments of two major river systems draining artisanal and small-scale gold mining (ASGM) communities of the Prestea-Huni Valley district, Southwestern Ghana. The miners extract gold (Au) through exclusive amalgam [Hg-Au] formation or cyanidation of Au-rich Hg-contaminated tailings, or a combination of both techniques. Hg water solubility and probable mercuric compounds in sediments of Hg-contaminated CN-loaded (River Aprepre) and Hg-contaminated non-CN (River Ankobra) aquatic systems within the district were investigated. THg was determined by CV-AAS after HF/HNO3/HCl digestion. MeHg in sediments were extracted with H2SO4/KBr/CuSO4-CH2Cl2; followed by aqueous-phase propylation, preconcentration-on-Tenax, and GC-CV-AFS. River Aprepre showed 4.58-14.83 ngMeHg/g as Hg (1.4-3.7% THg as MeHg), with 241-415 ngTHg/g, and 0.05-0.21 mgCN/kg. For River Ankobra, MeHg ranged 0.24-1.21 ngMeHg/g (0.08-0.35% THg as MeHg) with 162-490 ngTHg/g dw and CN <0.001mg/kg. There was positive correlation (r2=0.5974; p<0.01) between MeHg and CN in River Aprepre. The water-soluble fraction of Hg in sediment from both rivers was <1% of THg. Hg in sediments from River Aprepre were generally more soluble than that from River Ankobra, indicating that Hg in sediments from River Aprepre were potentially more bioavailable for methylation. Accordingly, the presence of CN in Hg-dominated river sediments potentially influences and enhances the solubility and mobility of Hg, resulting in increased Hg methylation rates.

Mercury Exposure in Artisanal and Small-Scale Gold Mining Communities in Sukabumi, Indonesia.

Background.Artisanal and small-scale gold mining (ASGM) is one of the largest sources of mercury (Hg) pollution in Indonesia. In West Java Province, ASGM is found in Bogor, Cianjur, and Sukabumi Regencies.Objectives.The present study aimed to evaluate Hg contamination effects and socioeconomic factors in communities living around ASGM operations in Sukabumi Regency.Methods.A quantitative method was used to describe socioeconomic ASGM communities. The concentrations of total mercury (T-Hg) in hair were measured in 71 respondents. This study also assessed perception of the use of Hg in the gold ore processing and their impact on the environment.Results.The population of gold miners in the studied three villages was 1300 households (25.77% from a total of 5044 households). Artisanal and small-scale gold mining involves both men and women employed as miners and gold amalgam processors, respectively. The average monthly income generated as much as Indonesian Rupiah (IDR) 272 000–2 000 000 (about 19–140 USD). Total Hg analysis was conducted for hair samples of 71 respondents (38 men, 33 women). The results showed an average T-Hg in men of 3.27±2.89 ppm, and women of 5.91±4.69 ppm. The level of T-Hg in the respondents was associated with distance to the ball mills and not related to distance to the mine site.Participant Consent.ObtainedEthics Approval.This study was approved by Ministry of Environment and Forestry of the Republic of IndonesiaCompeting Interests.The authors declare no competing financial interests.

Dried blood spots to characterize mercury speciation and exposure in a Colombian artisanal and small-scale gold mining community

The artisanal and small-scale gold mining (ASGM) sector uses the most mercury (Hg) worldwide. Despite health concerns associated with high Hg exposures in these communities, ASGM sites are often situated in resource limited and remote regions which challenge traditional human biomonitoring approaches. To help overcome such challenges, here we report on the development of a high-quality method to characterize chemical speciation of Hg in dried blood spots (DBS), and then apply this method to assess Hg exposures in people sampled from an ASGM community (Pueblito Mejia) and a nearby town (Barranco de Loba) in Colombia. We collected DBS and urine samples from 35 individuals in 2018, and used these to assess occupational (DBS inorganic Hg (InHg) and urine total Hg (THg) measures) and environmental (DBS methylmercury (MeHg) measures) exposure of participants to different forms of Hg. The accuracy and precision of the DBS-based measures generally met assay performance guideline. In study participants, the mean concentrations of DBS MeHg, InHg, and THg, and urine THg were 1.9, 4.1, 6.0, and 3.1 μg/L, respectively. For 37% of the participants, DBS THg values exceeded the 5 μg/L ‘alert level’ proposed by the German HBM Commission. About 60% of the blood Hg was in the InHg form thus exemplifying a need to speciate Hg in blood sampled from ASGM sites to better understand the contributions of environmental and occupational exposure sources. This study demonstrates the feasibility of using DBS for Hg speciation exposure assessments in remote and resource-limited areas such as ASGM communities.

Occupational human exposure to mercury in artisanal small-scale gold mining communities of Colombia

With the aim of protecting human life and the environment, the Minamata Convention seeks to reduce and monitor mercury (Hg) concentrations in the environment. Artisanal and Small-scale Gold Mining (ASGM) has been identified as the most important anthropogenic source of Hg at a global scale and an important route of human exposure to Hg. In this context, this study assessed total Hg (THg) in blood, urine and hair, and methylmercury (MeHg) in human hair samples from 238 participants with occupational exposure to Hg in the most relevant ASGM communities of Colombia. Mercury concentrations in different biological matrices were related to several variables of interest such as age, gender, body mass index, fish consumption, exposure time, and specific occupational activities, such as amalgamation and amalgam burning. The median values of THg in blood (3.70 µg/L), urine (4.00 µg/L) and hair (1.37 mg/kg), and hair MeHg (1.47 mg/kg) for all participants were below permissible concentrations set by WHO. However, about 40% of the miners showed Hg concentrations in blood, urine and/or hair above the WHO thresholds. In all the biological matrices studied, miners burning amalgams showed significantly higher concentrations than miners who did not burn amalgams, with values 7-, 7-, and 8-fold higher in blood, urine and hair, respectively. A multiple linear regression model revealed that burning amalgam and fish consumption were significant predictors of Hg exposure in miners. Miners from Guainía had the highest concentrations in urine and hair, most likely due to the high manipulation and burning of amalgam, and a high fish consumption. In contrast, miners from Caldas showed the lowest Hg concentrations in all the biomarkers because they do not manipulate or burn amalgam, as well as reporting the lowest fish consumption. Our study also highlighted that gold miners exposure to Hg depends on their work practices. Therefore, the implementation of a health education programme on gold mining strategies is required, especially in Guaina, Vaupés, Córdoba, and Antioquia departments.