Accumulation and distribution of mercury in cacao (<i>Theobroma cacao</i>) grown in artisanal and small-scale gold mining areas, Ashanti Region, Ghana

Mercury is used in artisanal and small-scale gold mining (ASGM) to extract gold by forming an amalgam. This raises considerable concern about mercury pollution in the surrounding environment and plants. This study aimed to investigate mercury concentrations in soil and cacao in the ASGM area of Ghana and to evaluate the human health risk of mercury in cacao. Agricultural soil and cacao (root, leaf, bean, and pod) samples were collected from three ASGM communities (Manso Abore, Nweneso No. 1, and Nweneso No. 2) in the Ashanti Region of Ghana. The mean total mercury concentrations in the soil were 76±36 µg/kg dry weight (n=42), corresponding to moderate contamination by the contamination factor. In the cacao samples, the highest mean total mercury concentration was found in the roots (211 µg/kg dry weight, n=12) and lowest in the beans (27 µg/kg dry weight, n=12). The bioaccumulation and transfer factors indicated a high accumulation of mercury in the roots of cacao (bioaccumulation factor=3.1) from the soil but a lesser accumulation in the aerial parts from the roots (transfer factor<1). The health risk assessment from the ingestion of cacao beans indicated no possibility of noncarcinogenic health effects (hazard quotient<1). Continuous mercury pollution may lead to accumulation along the food chain, which may be detrimental to human health. Therefore, strict measures and monitoring in ASGM communities are needed to protect human health.