Medical geological study of disease-causing elements in Wassa area of Southwest Ghana

Insufficient information on the link between health data and geology in developing countries is a major barrier to identify sources of some emerging public health problems. A total of 2868 soil samples were collected from field sheet 0503B in Ghana to evaluate the concentrations and distributions of trace elements and their effects on human health. The samples were sieved to < 106 µm fraction and analysed for elements, As, Ba, K, Zn, Co, Cr, Cu, Mn, Ni, Pb, Mg and Fe by XRF technique and Au by fire assay method. The study identified disparities in averages of As, Cr, Fe and Mg, which resulted in enrichment and deficiencies when compared with the worldwide background average. The measured averages for As and Cr were 17.27 mg/kg and 89.25 mg/kg, respectively, for the entire area. Both averages exceeded the worldwide background values of 10 mg/kg and 8 mg/kg of As and Cr. The four traditional towns with varied activities recorded As concentrations ranging from 6.11 mg/kg at Samreboi, 16.29 mg/kg at Asankragwa, 17.42 mg/kg at Akropong and 25.99 mg/kg at Bogoso. Principal component analysis revealed a good association among Ba, Cr, Cu, Fe, K, Ni, Pb and Zn in Group 1, and their main source was interpreted as the underlying geology. Arsenic, Cr and Mg in Group 2 show a relatively weak correlation, and their sources were ascribed to a combination of geologic and anthropogenic sources. Gold had a good correlation with As, which was associated with the hydrothermal veins in the underlying rocks. The spatial plots generated from transformed soil data by Getis Ord Gi* treatments were visual methods to clearly identify geographically the hotspots and coldspots of elements that cause diseases.