Industrial Impact on Selected Heavy Metals in Economic Crops

Abstract

Industrial impact on selected heavy metal concentrations in economic food crops samples of Nnewi-North, Anambra State, Nigeria was studied.  The levels of seven heavy metals (Pb, Mn, Zn, Ni, Cr, Cu, and Cd) in common food crops (Manihot esculenta, Colocasia esculenta, Vernonia amygdalina, Corchorus olitorius) from the area were determined using Flame Atomic Absorption Spectrophotometric technique. The HNO₃-H₂O₂ method was used in the food sample digestion. The mean concentrations (µg/g), of heavy metals in the food crops from the studied area were 2,72 for Pb, 5.10 for Mn, 19.42 for Zn, 0.97 for Ni, 5.79 for Cr, 5.75 for Cu, 0.61 for Cd and were higher than samples from the control sites although they were within the acceptable levels in food crops with the exception of Pb and Cd. The THQ and HI values were evaluated in order to assess the health risk of the inhabitants of Nnewi-north and environs due to heavy metal intake from food crops. The correlation coefficients and their properties were generated, proved and applied to the variable series of heavy metals investigated in the study. The correlations for most of the pairs of heavy metals considered were found to be significant. The values were less than 1 in all the food crops signifying that their consumption does not pose any health risk. In conclusion, the investigated area has been affected by the industrial activities and so control measures should be enforced by regulatory authorities.