Contamination and Human Health Risk Assessment of Potentially Toxic Elements in Agricultural Soil at Binduri District, Upper East Region, Ghana.

Abstract

The contamination of agricultural soil by potentially toxic elements (PTEs) remains global human and environmental concerns. This study assessed the levels of PTEs in the agricultural soil in the Binduri district, upper east region and estimated the contamination status as well as risk to the ecology and human health. A total of 80 agricultural soil samples were collected and concentrations of 11 different PTEs (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Ti, V, and Zn) were analyzed using a Niton XL3t GOLDD+ X – ray fluorescence (XRF) analyzer. The mean concentrations of the PTEs in mg/kg in the samples were 2.909, 19.427, 74.886, 24.276, 240.927, 32.539, 4.159, 1991.816, 39.32, and 37.966 for As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Ti, V, and Zn respectively. The results indicated a substantial build – up of PTEs in the agricultural soil at the study area compared to natural abundance. The mean concentration of cadmium and cobalt (19.472 mg/kg and 74.886 mg/kg) respectively exceeded the acceptable limits by CCME soil quality guidelines of (1.4 mg/kg and 40 mg/kg) respectively amongst the 11 elements analyzed. The pollution status of the agricultural soil at the study area were determined using the various pollution estimation models including; geoaccumulation index, contamination factor, enrichment factor, potential ecological risk, Nemerow’s pollution load index, and pollution load index. The results of the pollution estimation models indicated that Cd and Co were the most significant pollutants. The risk assessment was determined, taking into account all the exposure route (ingestion, inhalation and dermal), for both adults and children. The results showed that children were more at risk than adults. The non – carcinogenic risk (HI) values for adults and children were found to be above 1, indicating a high risk. The carcinogenic risk (CR) values for adults and children were also found to be significant with Co and Cd contributing the most to the risk. The sources of contamination were identified as anthropogenic activities such as auto-mechanic services, the use of fertilizer and pesticides, improper waste disposal, mining from the nearby communities and districts, and irrigation with contaminated water. The study highlights the importance of monitoring potentially toxic elements in agricultural soil to protect human health.