A review on bioaccessibility and the associated health risks due to heavy metal pollution in coal mines: Content and trend analysis

Abstract

On the verge of just transition leading to phase-wise closure of coal mines worldwide, coal mine reclamation and eco-restoration will emerge as the major activity in the coming decades. Hence the pollution of heavy metals by coal mining activities also needs attention. This review paper encapsulates the accessible data in the literature on metals polluted particulate, soil, and dust derived from the coal mining area. It evaluates the bio-accessibility of metals present in coal mining, the human health risk assessment, and its carcinogenic and non-carcinogenic health risk assessment for adults and children. It was observed that the metals like Zn, Pb, Cu, Hg, Cd, Cr, and As are most commonly found in the coal mine area. It was also found that Ni, Cu, Cr, Co, and As are more bioaccessible, and concentration was higher in the gastric phase as compared to the intestinal phase. Human health risk assessment disclosed that children are more affected than adults, and more non-carcinogenic effects are widespread than carcinogenic ones. Metals like Pb and Zn cause more non-carcinogenic effects and metals like Cd lead to more carcinogenic effects on human health, while metals like Cr and As are involved in causing both carcinogenic and non-carcinogenic effects in adults and children. Bibliometric and content analysis suggested that there are few heavy metal contamination studies performed in the coal mine areas. In contrast, studies relating to assessing metal bioaccessibility and health risks in the coal mine area are relatively scarce. Finally, the gaps identified were defining the role of pH and particle size affecting bioaccessibility of metals in coal mines, the correlation between in-vitro and in vivo metal concentrations, and more clarification of Rfd values for health risk calculation.