Potential health risk of heavy metals in some selected vegetable crops at an artisanal gold mining site: A case study at Moseaso in the Wassa Amenfi West District of Ghana

Activities of artisanal mining pose ecological as well as health challenges through the release of heavy metals into the environment. This study assessed the potential risk of heavy metals in some selected vegetables at an artisanal gold mining site at Moseaso in the Wassa-Amenfi West District of Ghana. A total of 40 soil samples were collected from the study area at depth of 20 cm using a soil auger. At each site two each of the selected vegetables (tomatoes, spring onion, and lettuce) were sampled from the farms. Also, 9 water samples were also taken at sections of the stream (upstream, midstream, and downstream) for the analysis of As, Cd, Pb, and Hg using Atomic Absorption Spectroscopy. The results of the study revealed that the mean concentration of As (22.92 mg/kg), Cd (5.41 mg/kg), Pb (98.01 mg/kg), and Hg (0.81 mg/kg) in soils from the artisanal gold mining sites were all above the stipulated limits. The mean values of As, Cd, Pb, and Hg in the stream water were beyond the stipulated limit of 0.01, 0.03, 0.01, and 0.03 mg/l, respectively. Also, all the examined heavy metals in the selected food crops were above the reference limit. The bioaccumulation factor in the food crops was less than 1 except for cadmium which had a BF>1 in tomatoes, spring onion, and lettuce. The cancer risk assessment also revealed that, with the exception of Pb, all the heavy metals considered were above the USEPA-safe prescriptions of 1.0 × 10−6 to 1.0 × 10−4 for both adults and children. Based on the results, it can be recommended that the dietary intake of vegetables grown from the study site is not safe and poses severe health and environmental threats.