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.This study was performed in the framework of several projects: the (MME) GGC N° 223 - 2015 (UPME) CI-002-2015, funded by the Ministry of Mines and Energy, the Mining and Energy Planning Unit (UPME), and the University of Córdoba, and the Inter-administrative Agreement N° 407 - 2016, financed by the Ministry of Health and Social Protection, the National Health Institute and the University of Córdoba.Peer reviewe