Trace element content in cereals from a gold mining site in Burkina Faso and intake risk assessment

Cereals grown close to mining sites could contain high levels of trace elements which could jeopardize local population health through intake of those crops. This study investigated for the first time the concentration of trace elements, namely arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc in four types of cereals (two of maize and two of sorghum) grown within the perimeter of a gold mine and at three surrounding villages in Burkina Faso. A total of 47 samples were taken. Cereal consumption surveys in those villages were undertaken to evaluate the intake hazard. Average arsenic content trend was Site (0.31 ± 0.56 mg kgdw⁻¹) > Songo (0.18 ± 0.17 mg kgdw⁻¹) > Sighnoguin (0.15 ± 0.10 mg kgdw⁻¹) > Youga (0.10 ± 0.00 mg kgdw⁻¹); subsequently, the average estimated daily intake of Arsenic followed this pattern: Site > Songo > Sighnoguin > Youga with 1.93, 1.08, 0.89 and 0.63 μg kgbw⁻¹ day⁻¹ respectively which all fall below a target hazard quotient of 1. Non-parametric Kruskal-Wallis tests confirmed significant difference of Co, Cu, Fe, Mn and Ni between locations whilst not significant differences were found for As, Cd, Pb and Zn. Considering cereals types, yellow corn from the mine site exhibited As value higher than the Referential dose (2.14 μg kgbw⁻¹ day⁻¹) and consequently a target hazard quotient of 1.97. This finding indicates that there is an intake risk to the local population from dietary intake. Contamination by As could be linked to mining activities on parent rocks that contain As with spread by wind to Songo and Youga. Sighnoguin village is more subject to contamination by agricultural practices. Decontamination of the site and selection of cereals with low uptake capability and some changes to agricultural practices could reduce the hazards.