Assessing Heavy Metal Contamination Risk in Selected Vegetables Marketed in Dutsin-Ma, Katsina State, Nigeria

Abstract

The study investigated the presence of heavy metals (Cd, Cu, Fe, Mn, and Pb) in cabbage, lettuce, onion, pepper, and tomato, as well as evaluated the potential human health risks/hazard that might be caused due to their consumption. Their concentrations were determined using atomic absorption spectrophotometer and subsequently transformed in evaluating their health risks via estimation using estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR). The concentrations of the trace metals detected were in the range of 0.02 ± 0.00 to 0.20 ± 0.01; 0.12 ± 0.00 to 0.43 ± 0.30; 0.60 ± 0.5 to 21.77 ± 0.02; 0.70 ± 0.02 to 3.01 ± 0.00; and 0.03 ± 0.00 to 0.67 ± 0.01 mg/kg, for Cd, Cu, Fe, Mn, and Pb respectively. Lettuce has the highest concentration of lead (0.67 mg/kg), whereas Pepper has the least (0.03 mg/kg). In all the samples analyzed, except for Pepper, the lead concentrations were greater than WHO/FAO recommended level. The EDI values of all metals in question were below the maximum tolerable daily intake (MTDI). The total target hazard quotient (TTHQ) was less than 1, in all the samples examined, hence posing no threat to human health. Also, there is no alarm for cancer as the TCR values for all samples were  4.93 × 10⁻⁸ for Pb which is less than the threshold value of USEPA (10⁻⁶), indicating that the consumers’ residents of these vegetables are not exposed to Pb. However, regular monitoring of Pb metal in vegetables should be carried out to avoid heavy metal toxicity associated with the consumption of those vegetables.