Human health risk assessment of potential toxic elements in paddy soil and rice (Oryza sativa) from Ugbawka fields, Enugu, Nigeria

Abstract

The potential toxic elements (Cu, Zn, Pb, Ni, Fe, Cr, Cd, Mn and Hg) were accumulated from rice grains and soil from an Ugbawka farm, Enugu State, Nigeria, which were determined to evaluate the potential health risk to rice consumers. The mean levels of metals found in soil (mg/kg) were as follows: Ni (0.57±0.24), Pb (2.44±0.17), Zn (3.35±2.05), Cu (0.71±0.33), Mn (37.72±10.97), Fe (13 856.6±31.43), Cr (2.51±0.98), Cd (0.51±1.36), and Hg (0.02±0.38); however metals found in rice grains (mg/ kg) were: Ni (0.81±0.72), Pb (0.94±0.70), Zn (8.22±2.97), Cu (0.59±0.42), Mn (13.30±4.56), Fe (13.28±0.73), Cr (15.00±10.00), Cd (0.36±0.07), and Hg (0.002±0.23). A small percentage (2.5%) of the soil samples were above the Chinese Maximum Allowable Concentration for cadmium in soil while cadmium and lead levels in the rice grains were above WHO permissible limit. Pearson’s correlations showed significant correlations amongst some metal pairs in soil and grains showing similarity in origin. The estimated daily intake of Pb was higher than the safety levels given by JECFA. Hazard Quotient for Pb and Total Hazard Index of all the metals were above one. This indicates possible potential health risk and adverse effect resulting from consumption of rice from Ugbawka farm.

Keywords

• potential toxic elements
• rice
• soil
• hazard quotient
• total hazard index