Human Biomonitoring Data from Mercury Exposed Miners in Six Artisanal Small-Scale Gold Mining Areas in Asia and Africa

Objectives: In artisanal small-scale gold mining (ASGM) areas in many developing countries, mercury (Hg) is used to extract gold from ore. Data of 1250 participants from Indonesia, Mongolia, Philippines, Tanzania, and Zimbabwe were combined to analyze the relation between exposure in ASGM areas and body burden. Methods: Four groups were selected relating to their intensity of contact with mercury: (i) a non-exposed control group; (ii) a low exposed group with participants only living in mining areas, but not working as miners; (iii) a medium exposed group, miners living in exposed areas and working with mercury without smelting amalgam; and (iv) a high exposed group, miners living in exposed areas and smelting amalgam. Results: Compared to the non-exposed control group, participants living and/or miners working in highly exposed areas have significantly higher concentration of total mercury in urine, hair and blood (p-value < 0.001). The median mercury value in urine in the control group is < 0.2 mu g/L. In the high exposed group of amalgam smelters, the median in urine is 12.0 mu g/L. The median in blood in the control group is < 0.93 mu g/L. The median level in blood of the high exposed group is 7.56 mu g/L. The median for mercury in hair samples from the control group is 0.21 mu g/g. In the high exposed group the median hair concentration is 2.4 mu g/g hair. Mercury levels also differ considerably between the countries, reflecting a diverse background burden due to different fish eating habits and different work place methods. Conclusions: A high percentage of exposed individuals had levels above threshold values. These high levels of mercury are likely to be related with serious health problems