Artisanal Small-scale Gold Mining Area Research Articles

Mercury Contamination from Artisanal Small-scale Gold Mining Activities in Simpenan District, Sukabumi Regency, West Java, Indonesia

Mercury is still used in the amalgamation process in small-scale gold processing. This study aims to evaluate the mercury contamination of various environmental media in the artisanal small-scale gold mining (ASGM) area in the Simpenan District, Sukabumi Regency. The ecological media examined in this study included groundwater, river water, soil, sediment, biota, and plants. The threshold number was determined using APHA 3125 and Indonesian National Standard (SNI) 7387:2009. Meanwhile, the mercury concentration in the ambient air was measured directly using a mercury analyser. Mercury concentrations in the water, soil, sediment, biota, and plant matrices were calculated using a calibration curve. The study found that the levels of mercury in groundwater, river water, and sediment were all below the applicable quality standards of <0.0001, <0.0001 and 0.001 mg/L, respectively. However, the levels of mercury in soil and plants were 27.28 and 0.52 mg/kg, respectively. Additionally, the levels of mercury in four types of fish found in a river adjacent to the ASGM location, namely beunteur (0.33 mg/kg), snakehead (0.05 mg/kg), catfish (0.26 mg/kg) and eel (0.20 mg/kg), exceeded the specified quality standards. In conclusion, mercury contamination is present in the soil, plants, and aquatic biota (fish) in the ASGM area in the Simpenan District, Sukabumi Regency.

Rural Knowledge Transformation in Terms of Mercury Used in Artisanal Small-Scale Gold Mining (ASGM)-A Case Study in Gorontalo, Indonesia.

Gorontalo is reputed to be one of the best-quality gold producers in the Indonesian archipelago. Gold production has been largely achieved through the activities of artisanal small-scale gold mining (ASGM), which as part of its extraction process, primarily uses mercury-a substance known to cause negative impacts on health and the environment, leading also to numerous socio-economic issues. This research aims (1) to investigate the extent of rural knowledge regarding mercury and to determine whether a video that explains mercury and the problems that occur as a result of ASGM can significantly transform rural populations' knowledge; (2) to inspect different factors separating the SR group (those who live in the same regency as the ASGM area) from the NR group (those who live in the neighboring regency/city of the ASGM area) and to find out whether said factors are statistically significant. The results show that the test subjects' knowledge of mercury had increased after watching the video, and that their willingness to oppose ASGM activities is one of the significant factors within the two groups. Moreover, this paper briefly describes the follow-up activities of the SRIREP project (Co-creation of Sustainable Regional Innovation for Reducing Risk of High-impact Environmental Pollution) in encouraging rural communities to explore sustainable livelihoods as an alternative to ASGM.

Validation of Mercury Speciation Analysis in River Around Artisanal Small-Scale Gold Mining Area in West Nusa Tenggara, Indonesia

A method for determining mercury concentration using a mercury analyzer in a river water sample was validated according to ISO/IEC 17025. Analytical performance including linear range, limit of detection, precision and accuracy were evaluated. Mercury speciation profile was obtained from Pelangan River at three areas within Dusun Rambut Petung, an area with the highest amount of artisanal small-scale gold mining (ASGM) in Lombok, West Nusa Tenggara. Then, their concentration in each species was measured using sequential extraction. Good curve linearity was obtained in the concentration range of 0.1-5.0 µg/L and the limit of detection was 0.014 µg/L. The developed method has good precision and accuracy with a RSD value <10% and a recovery of 94.16-101.91%. The detected fraction of mercury in the Pelangan river is organomercury, elemental mercury, and sulfide-bound species with each concentration of 0.732±0.032; 0.350±0.027; and 0.850±0.027 µg/L, respectively. The measurement results showed conformity with the reference method using CV-AAS. Therefore, this method can be applied to determine mercury levels in water for monitoring environmental quality.

The Determination of Algae Group as Bioindicator of Water Quality Change Affected by Mercury Release from Artisanal Small-Scale Gold Mining (ASGM)

Artisanal small scale gold mining (ASGM) practices typically use mercury for amalgamation. Near water environments this can degrade water quality and aquatic biota, including algae. Changes in algal communities can reflect water environment disturbance. The aim of this study was to determine if algae can be used as bioindicator of river water quality impacted by ASGM activities. The research was conducted from July to October 2018 at thirty sampling sites along rivers near ASGM areas in several regencies of Indonesia. Composite samples of water and sediment were collected. A plankton net and brushing methods were used to collect planktonic and benthic algae, respectively. The physicochemical parameters of the water and the sediment as well as the dominant algae genera were analyzed statistically with principal component analysis. The results showed that the total mercury concentration in the water ranged from <0.04 to 20 µg.L-1, while in the sediment the maximum value was 13,500 µg.kg-1. The total mercury content in the sediment was negatively correlated with the dominant benthic Navicula at a significance level of p < 0.05. This means that a low density of benthic Navicula can be proposed as a bioindicator of water quality, indicating the increase of mercury pollution in sediment.

Change Detection of Amazonian Alluvial Gold Mining Using Deep Learning and Sentinel-2 Imagery

Monitoring changes within the land surface and open water bodies is critical for natural resource management, conservation, and environmental policy. While the use of satellite imagery for these purposes is common, fine-scale change detection can be a technical challenge. Difficulties arise from variable atmospheric conditions and the problem of assigning pixels to individual objects. We examined the degree to which two machine learning approaches can better characterize change detection in the context of a current conservation challenge, artisanal small-scale gold mining (ASGM). We obtained Sentinel-2 imagery and consulted with domain experts to construct an open-source labeled land-cover change dataset. The focus of this dataset is the Madre de Dios (MDD) region in Peru, a hotspot of ASGM activity. We also generated datasets of active ASGM areas in other countries (Venezuela, Indonesia, and Myanmar) for out-of-sample testing. With these labeled data, we utilized a supervised (E-ReCNN) and semi-supervised (SVM-STV) approach to study binary and multi-class change within mining ponds in the MDD region. Additionally, we tested how the inclusion of multiple channels, histogram matching, and La*b* color metrics improved the performance of the models and reduced the influence of atmospheric effects. Empirical results show that the supervised E-ReCNN method on 6-Channel histogram-matched images generated the most accurate detection of change not only in the focal region (Kappa: 0.92 (± 0.04), Jaccard: 0.88 (± 0.07), F1: 0.88 (± 0.05)) but also in the out-of-sample prediction regions (Kappa: 0.90 (± 0.03), Jaccard: 0.84 (± 0.04), and F1: 0.77 (± 0.04)). While semi-supervised methods did not perform as accurately on 6- or 10-channel imagery, histogram matching and the inclusion of La*b* metrics generated accurate results with low memory and resource costs. These results show that E-ReCNN is capable of accurately detecting specific and object-oriented environmental changes related to ASGM. E-ReCNN is scalable to areas outside the focal area and is a method of change detection that can be extended to other forms of land-use modification.

Human health risk assessment of atmospheric mercury inhalation around three artisanal small-scale gold mining areas in Indonesia

To clarify the human health risk of inhalation of gaseous elemental mercury (GEM), we measured GEM concentrations in three artisanal small-scale gold mining (ASGM) areas of Palu (Central Sulawesi), Muara Aman (Benkulu in Sumatra), and Palangka Raya (Central Kalimantan).

Mercury pollution in water and its effect on renal function of school age children in gold mining area Sekotong West Lombok

Artisanal small-scale gold mining (ASGM) has affected environment, since gold processing released mercury into the environment. Contaminated water was used as drinking water and affected human body. Kidney is one of affected organ by mercury, where children population is vulnerable for poisioned. The objective of this research was to find out mercury pollution in drinking water and its effect on renal function of children in ASGM area Sekotong in West Lombok. This preliminary study design was cross sectional. Sample of drinking water collected from various sources in Taman Sari and Telaga Lebur village. Mercury was assessed by using AAS. Renal function was evaluated from urine sample by using dipstick kit to perform proteinuria. Correlation between contaminated water consumption and renal function was statistically analyzed by Spearman’s test. Mercury level found in water samples taken from well was 4.009 ppb, while from wellspring was 0.724 ppb and 0 ppb from pipe. From 15s samples, 12s samples higher than mercury threshold for drinking water. Two of 30s school age children had positive proteinuria. Spearman’s test showed P-value of 0.000. It concluded that drinking water in ASGM Sekotong West Lombok has been contaminated by mercury and affected kidney function of school-age children.

Environmental Risk and Health Hazardous Substances in Artisanal Small-Scaled Gold Mining in Sekotong, West Nusa Tenggara, Indonesia

Gold (Au), copper (Cu) and nickel (Ni) are mined within Indonesia’s Archipelago as predominantly a mineral-rich country. Au is the worthiest metals compare to all these minerals over the years. Because of that reason, gold mining is one of major economic activity in Indonesia participated through by large-scale, artisanal and small-scale entities Artisanal Small-Scale Gold Mining (ASGM) has been a source of chances for employment and subsistence to thousands of people. On the contrary, artisanal small-scale gold mining contributes to serious environmental and health issues for miners, nearby populations, and larger society when the use of mercury (Hg) occurs. This study aims to review environmental risk and health-hazardous substances in Artisanal Small-Scaled Gold Mining in Sekotong, West Nusa Tenggara, Indonesia which also emphasized geological data from the former study. The results showed that Sekotong’s ASGM area is centered by three hydrothermal alteration halos developing from proximal argillic, distal propylitic and superimposed advance argillic alteration also capped by ore mineralization. A high-dense mineralized stockwork of quartz vein as the main characterization founded. Under those circumstances, pledge local miners around the area to execute the prospects without knowing self-assessment and investigation. In conclusion, Sekotong’s ASGM area became one of the shortlisted areas that investigating the effects of mercury on the environment and people’s health signifies urgently necessary for developing a better solution to eliminate further mercury contamination to the environment in Sekotong’s ASGM area due to the extraction of the prospects before another catastrophe befalls.

Mercury concentration in hair collected from women in artisanal small-scale gold mining areas in Camarines Norte, Philippines

After the conclusion of the Minamata Convention on Mercury, the use of mercury (Hg) has been prohibited worldwide, except in some developing countries. The Republic of the Philippines is one of the 128 signatories of the Convention. There are many artisanal and small-scale gold mining (ASGM) operations in the Philippines that still use Hg to amalgamate gold. In order to know the direct effect of exposure to Hg on women’s hair, we performed the proton-induced X-ray emission analysis of Hg concentrations in the hair samples collected from women at risk of Hg contamination, in both ASGM and non-ASGM areas in Camarines Norte, Philippines. At the same time of the hair sampling, we also conducted interviews with the women about their lives. From the analysis results, we found that the range of Hg concentrations in the hair samples was at a safe level, with no significant difference between the ASGM and non-ASGM areas. An analysis of the effect of diet on Hg concentrations in the hair samples showed a tendency toward higher Hg concentrations in women who ate more fish. Our results through hair analysis did not show a direct effect of exposure to atmospheric Hg, but further survey of local people should be necessary to reduce the risk of Hg contamination in women even after the use of Hg in ASGM eventually comes to an end.

Mercury concentrations in paddy field soil and freshwater snails around a small-scale gold mining area, West Java, Indonesia

To estimate the impact of mercury released from an artisanal small-scale gold mining (ASGM) activities on the ecosystem. Total and organic mercury concentrations in paddy field soil and freshwater snails around an artisanal small-scale gold mining area were investigated. Paddy field soil samples and freshwater snails were collected from ten sites along the Cikaniki River. A site located in a national park, which was approximately 12 km upstream from the ASGM site, was considered the reference site for this study. The organic mercury concentration in soil samples collected at the ASGM site was n.d.–0.018 mg kg−1 and that at the reference site was 0.005–0.008 mg kg−1. The organic mercury concentrations in the freshwater snails collected at the ASGM and reference sites were 0.38 ± 0.21 mg kg−1 (31.0 ± 26.6% of total mercury, n = 38) and 0.056 ± 0.032 mg kg−1 (40.5 ± 11.5% of total mercury, n = 16), respectively. Although the original form of mercury in the mining waste was elemental mercury and/or Hg2+, the mercury form changed to organic mercury in environment and the organic mercury was concentrated two orders of magnitude, even in low-order organisms.

The dietary intake of mercury from rice and human health risk in artisanal small-scale gold mining area, Indonesia

The dietary intake of mercury from rice and human health risk in artisanal small-scale gold mining area, Indonesia

The evaluation of mercury contamination in upland rice paddy field around artisanal small-scale gold mining area, Lebaksitu, Indonesia

The evaluation of mercury contamination in upland rice paddy field around artisanal small-scale gold mining area, Lebaksitu, Indonesia

Risk of Mercury Exposure from Fish Consumption at Artisanal Small-Scale Gold Mining Areas in West Nusa Tenggara, Indonesia.

Background.The primary environmental risk associated with artisanal small-scale gold mining (ASGM) activities in Sekotong and Taliwang is waste discharged directly into the environment. This waste contains variable concentrations of heavy metals and a high level of mercury. When these elements are released into the environment, plants and animals can be contaminated. If mercury is methylated to methylmercury, levels can increase in concentration at each level of the food chain (biomagnify). Fish are a primary risk vector for methylmercury poisoning in humans, and represent a significant source of protein for the Sekotong and Taliwang communities.Objectives.The present study aimed to identify the concentration of mercury in fish from ASGM sites in Sekotong and Taliwang.Methods.Descriptive research was used to describe the mercury concentrations of fish in the present study. The fish species collected for the samples represented commercially available fish most commonly consumed by the community on a daily basis.Results.In Sekotong's ASGM area, the mercury concentration in Pilsbryoconcha exilis tissue was 596 ppb, 721 ppb for Sephia officinalis and 50% of the Euthynnus affinis samples had a high level of mercury, above the World Health Organization (WHO) maximum permissable limit for the sale of fish for human consumption of 0.5 ppb.Conclusions.Some fish species from the studied ASGM sites had high mercury concentrations above the maximum permissible mercury concentration in edible fish tissue. The risks associated with mercury exposure from fish consumption threaten community health.Ethics Approval.All experiments were performed in accordance with relevant local guidelines and regulations.Competing Interests.The authors declare no competing financial interests.

ASGM status in West Nusa Tenggara Province, Indonesia

Artisanal Small-Scale Gold Mining (ASGM) obviously contributes to serious environmental and health issue for miners, nearby populations, and larger community when the use of mercury (Hg) occurs. Mercury amalgamation is used as a gold recovery technique by 10-12 million ASGM miners around the world and a predicted around 1000 tons of mercury are discharged into the environment every year as a result of poor mining practices. Exposure to mercury can cause serious health effects for future generation, and miners and their families are vulnarable group to expose with mercury vapor and methyl mercury contaminated food in ASGM areas, resulting in increase of levels of mercury in human specimens. Thus, investigate the the effects of mercury on the environment and people health are urgently necessary for developing a better solution to eliminate further mercury contamination to environment in West Nusa Tenggara (WNT) Province. A field survey had been conducted for this research in two main ASGM spots in WNT Province: Sekotong-Lombok island and Taliwang-Sumbawa island. As part of the study, an initial health survey and socio-economic of workers/miners was conducted. Volunteer participants at sampling locations across Sekotong-Lombok and Taliwang-Sumbawa (exposed; indirect exposed; non exposed groups) answered a questionnaire, and allowed the sampling of hair for subsequent analysis. The ore, tailing, plants and soil samples were also collected for investigating Hg concentration on the substances. The results found that the impact of ASGM on increasing economic activity leading to jobs, income and opportunities for social development is positive. However, there is risk of contamination in soil and plants environment through mining activity and high Hg concentration discovered in human body in a short time of ASGM activity. The environmental sustainability of mining can be better regulated within legalised areas. Environmental monitoring will define unacceptable risk and allow for advanced implementation of remedial measures before an uncontrollable disaster occurs.

Economic features of the artisanal and small-scale gold mining industry in Bombana, Southeast Sulawesi, Indonesia

There is a consensus that the artisanal small-scale gold mining (ASGM) sector contributes to trapping individuals in a cycle of poverty and financial insecurity with a low standard of living. The purpose of this study was to analyze the economic circumstances of miners in the Bombana ASGM area in Indonesia using a mixed methodology approach that involved collecting, analyzing, and mixing both quantitative and qualitative data in a single study. Results show that the average and maximum monthly incomes of 201 miner households were Rp. 4,360,000 and Rp. 9,750,000, respectively. The average income in the ASGM area in Bombana was higher than that at similar sites on Java Island (∼Rp. 2,900,000) and was much higher than the average monthly income of the inhabitants of Bombana (∼Rp. 2,100,000). Because of the higher revenue generated in the ASGM sector, miners and their families depend long-term on the mining work, which makes it difficult to control the mining activity and the associated environmental degradation.

Signs and symptoms of mercury-exposed gold miners.

Gold miners use mercury to extract gold from ore adding liquid mercury to the milled gold-containing ore. This results in a mercury-gold compound, called amalgam. Miners smelt this amalgam to obtain gold, vaporizing it and finally inhaling the toxic mercury fumes. The objective was to merge and analyze data from different projects, to identify typical signs and symptoms of chronic inorganic mercury exposure. Miners and community members from various artisanal small-scale gold mining areas had been examined (Philippines, Mongolia, Tanzania, Zimbabwe, Indonesia). Data of several health assessments were pooled. Urine, blood and hair samples were analyzed for mercury (N = 1252). Questionnaires, standardized medical examinations and neuropsychological tests were used. Participants were grouped into: Controls (N = 209), living in an exposed area (N = 408), working with mercury as panners (N = 181), working with mercury as amalgam burners (N = 454). Chi2 test, linear trend test, Mann-Whitney test, Kruskal-Wallis test, correlation coefficient, Spearman's rho, and analysis of variance tests were used. An algorithm was used to define participants with chronic mercury intoxication. Mean mercury concentrations in all exposed subgroups were elevated and above threshold limits, with amalgam burners showing highest levels. Typical symptoms of chronic metallic mercury intoxication were tremor, ataxia, coordination problems, excessive salivation and metallic taste. Participants from the exposed groups showed poorer results in different neuropsychological tests in comparison to the control group. Fifty-four percent of the high-exposed group (amalgam burners) were diagnosed as being mercury-intoxicated, compared to 0% within the control group (Chi2 p < 0.001). Chronic mercury intoxication, with tremor, ataxia and other neurological symptoms together with a raised body burden of mercury was clinically diagnosed in exposed people in artisanal small-scale mining areas. The mercury exposure needs to be urgently reduced. Health care systems need to be prepared for this emerging problem of chronic mercury intoxication among exposed people. Int J Occup Med Environ Health 2017;30(2):249-269.

An inter-laboratory comparison of different analytical methods for the determination of monomethylmercury in various soil and sediment samples: A platform for method improvement

An inter-laboratory study was conducted to compare results from different analytical methods for monomethylmercury (MeHg) concentrations in 17 soil and sediment samples. The samples were collected from mercury-contaminated areas, including Minamata Bay and Kagoshima Bay in Japan, the Idrija mercury mine in Slovenia, and an artisanal small-scale gold mining area in Indonesia. The Hg in these samples comes from several different sources: industrial waste from an acetaldehyde production facility, volcanic activity, Hg mining activity, and artisanal and small-scale gold mining activity (ASGM). MeHg concentrations in all the samples were measured in four separate laboratories, using three different determination methods: Kagoshima University (Japan), using high-performance liquid chromatography–chemiluminescence detection (HPLC-CL); National Institute for Minamata Disease (Japan), using gas chromatography–electron capture detection; and Metropolitan Council Environmental Services (USA) and Jozef Stefan Institute (Slovenia), both using alkylation-gas chromatography–atomic fluorescence spectrometry detection. The methods gave comparable MeHg results for most of the samples tested, but for some samples, the results exhibited significant variability depending on the method used. The HPLC-CL method performed poorly when applied to samples with elevated sulfur concentrations, producing MeHg concentrations that were much lower than those from the other methods. Additional analytical work demonstrated the elimination of this sulfur interference when the method was modified to bind sulfur prior to the analytical step by using Hg2+ as a masking agent. These results demonstrate the value of laboratory intercomparison exercises in contributing to the improvement of analytical methods.

Essential Indicators Identifying Chronic Inorganic Mercury Intoxication: Pooled Analysis across Multiple Cross-Sectional Studies.

BackgroundThe continuous exposure to inorganic mercury vapour in artisanal small-scale gold mining (ASGM) areas leads to chronic health problems. It is therefore essential to have a quick, but reliable risk assessing tool to diagnose chronic inorganic mercury intoxication. This study re-evaluates the state-of-the-art toolkit to diagnose chronic inorganic mercury intoxication by analysing data from multiple pooled cross-sectional studies. The primary research question aims to reduce the currently used set of indicators without affecting essentially the capability to diagnose chronic inorganic mercury intoxication. In addition, a sensitivity analysis is performed on established biomonitoring exposure limits for mercury in blood, hair, urine and urine adjusted by creatinine, where the biomonitoring exposure limits are compared to thresholds most associated with chronic inorganic mercury intoxication in artisanal small-scale gold mining.MethodsHealth data from miners and community members in Indonesia, Tanzania and Zimbabwe were obtained as part of the Global Mercury Project and pooled into one dataset together with their biomarkers mercury in urine, blood and hair. The individual prognostic impact of the indicators on the diagnosis of mercury intoxication is quantified using logistic regression models. The selection is performed by a stepwise forward/backward selection. Different models are compared based on the Bayesian information criterion (BIC) and Cohen`s kappa is used to evaluate the level of agreement between the diagnosis of mercury intoxication based on the currently used set of indicators and the result based on our reduced set of indicators. The sensitivity analysis of biomarker exposure limits of mercury is based on a sequence of chi square tests.ResultsThe variable selection in logistic regression reduced the number of medical indicators from thirteen to ten in addition to the biomarkers. The estimated level of agreement using ten of thirteen medical indicators and all four biomarkers to diagnose chronic inorganic mercury intoxication yields a Cohen`s Kappa of 0.87. While in an additional stepwise selection the biomarker blood was not selected, the level of agreement based on ten medical indicators and only the three biomarkers urine, urine/creatinine and hair reduced Cohen`s Kappa to 0.46. The optimal cut-point for the biomarkers blood, hair, urine and urine/creatinine were estimated at 11. 6 μg/l, 3.84 μg/g, 24.4 μg/l and 4.26 μg/g, respectively.ConclusionThe results show that a reduction down to only ten indicators still allows a reliable diagnosis of chronic inorganic mercury intoxication. This reduction of indicators will simplify health assessments in artisanal small-scale gold mining areas.

Human health risk assessment of mercury vapor around artisanal small-scale gold mining area, Palu city, Central Sulawesi, Indonesia

Emissions of elemental mercury, Hg(0), from artisanal small-scale gold mining activities accounted for 37% of total global Hg(0) emissions in 2010. People who live near gold-mining areas may be exposed to high concentrations of Hg(0). Here, we assessed the human health risk due to Hg(0) exposure among residents of Palu city (Central Sulawesi Province, Indonesia). The area around the city has more than 60t of gold reserves, and the nearby Poboya area is the most active gold-mining site in Indonesia. Owing to its geography, the city experiences alternating land and sea breezes.Sampling was done over a period of 3 years (from 2010 Aug. to 2012 Dec.) intermittently with a passive sampler for Hg(0), a portable handheld mercury analyzer, and a mercury analyzer in four areas of the city and in the Poboya gold-processing area, as well as wind speeds and directions in one area of the city. The 24-h average concentration, wind speed, and wind direction data show that the ambient air in both the gold-processing area and the city was always covered by high concentration of mercury vapor. The Hg(0) concentration in the city was higher at night than in the daytime, owing to the effect of land breezes. These results indicate that the inhabitants of the city were always exposed to high concentrations of Hg(0).The average daytime point-sample Hg(0) concentrations in the city, as measured with a handheld mercury analyzer over 3 days in July 2011, ranged from 2096 to 3299ngm−3. In comparison, the average daytime Hg(0) concentration in the Poboya gold-processing area was 12,782ngm−3. All of these concentrations are substantially higher than the World Health Organization air-quality guideline for annual average Hg exposure (1000ngm−3). We used the point-sample concentrations to calculate hazard quotient ratios by means of a probabilistic risk assessment method. The results indicated that 93% of the sample population overall was at risk (hazard quotient ratio ≥1 and cut off at the 95th percentile value of the sample population) of mercury toxicity, that is, damage to the central nervous system due to chronic exposure. The corresponding percentages for the northern, central, southern, and western areas of the city were 83%, 84%, 95%, and 95%, respectively. Our results indicate that the residents of Palu city are at serious risk from exposure to high concentrations of atmospheric Hg(0).

Human exposure to mercury in artisanal small-scale gold mining areas of Kedougou region, Senegal, as a function of occupational activity and fish consumption.

We investigated mercury (Hg) exposure of food web and humans in the region of Kedougou, Senegal, where Hg is used for gold amalgamation in artisanal small-scale gold mining (ASGM). For this purpose, total mercury (THg) concentration was determined in eight fish species and two shellfish species from Gambia River and in human hair from 111 volunteers of different age and sex, living in urban locations (Kedougou and Samekouta) or in ASGM areas (Tinkoto and Bantako). THg concentrations in fish samples range from 0.03 to 0.51 mg kg(-1) wet weight (ww) and 0.5 to 1.05 mg kg(-1) ww for shellfish. THg concentrations in fish are below the WHO guideline of 0.5 mg kg(-1) ww, whereas 100 % of shellfish are above this safety guideline. In the entire set of fish and shellfish samples, we documented a decrease of THg concentrations with increasing selenium to mercury (Se:Hg) ratio suggesting a protection of Se against Hg. However, local population consuming fish from the Gambia River in the two ASGM areas have higher THg concentrations (median = 1.45 and 1.5 mg kg(-1) at Bantako and Tinkoto) in hair than those from others localities (median = 0.42 and 0.32 mg kg(-1) at Kedougou town and Samekouta) who have diverse diets. At ASGM sites, about 30 % of the local population present Hg concentrations in hair exceeding 1 mg kg(-1), defined as the reference concentration of Hg in hair. We also evidence a higher exposure of women to Hg in the Tinkoto ASGM site due to the traditional distribution of daily tasks where women are more involved in the burning of amalgams. The discrepancy between the calculated moderate exposure through fish consumption and the high Hg concentrations measured in hair suggest that fish consumption is not the only source of Hg exposure and that further studies should focus on direct exposure to elemental Hg of population living at ASGM sites.