The estimation of mercury exposure to workers through air deposition in the workshop of artisanal and small-scale gold mining

Abstract

Artisanal and small-scale gold mining (ASGM) environments have enriched concentrations of atmospheric mercury (Hg). Despite these conditions, ASGM workers are often accompanied by their family and small children as a part of their daily life. Furthermore, it can be considered that the elevated concentrations of airborne Hg in the workplace may also result in the contamination of food and drink consumed in the vicinity. Therefore, this study aimed to estimate Hg contamination of drinking water through air deposition in the ASGM workshop.

Atmospheric Hg(II) and Hg(0) concentrations in the studied ASGM workshops were between 0.0004 and 177 μg/m³ (average 30.1 μg/m³) and 5.53 and 4,190 μg/m³ (average 853 μg/m³), respectively. Hg (II) and Hg(0) both reached their highest concentrations when the amalgam was burned. The ratios of Hg (II) concentration to total atmospheric Hg in the workshop was also elevated during the amalgam burning process. Furthermore, Hg(II) concentrations in the workshop were higher than that in a house, which served as a control,even when amalgam was not burned, indicating that the amalgam combustion-generated Hg(II) is persistent in the environment.

Hg concentration in drinking water, which was collected in plastic (PP) cup put in the workshop, increased over a period of 24 h, with the proportion of Hg(II) rising from 0.5% before amalgam burning to 31% after the amalgam burning operation. This observation suggests that oxidized Hg, Hg(II), is easily dissolved in the aqueous phase; therefore, even the generation of gaseous Hg(II) can impact the health seriously.