Heavy Metals Contamination and Human Health Risk Asssessment Via Consumption of Medicinal Plants from Amassoma Community, Bayelsa State of Nigeria

Aims: Man-made activities such as excessive oil exploration, automobile emissions, gas flaring and agricultural activities tend to elevate the concentrations of heavy metals in the surrounding. Heavy metals have the tendency to accumulate in plant roots, which may result to heavy metal contamination.

Objectives: This study aimed at evaluating the concentration of heavy metals such as Lead (Pb), Cadmium (Cd), Nickel and Zinc (Zn) in Pawpaw fruits, seeds, leaf and Scent leaf from Amosoma community in Bayelsa State, Nigeria. The concentrations of these metals were used to assess the human health risk melted to the consumers of the vegetables and fruits.

Materials and Methods: Sixteen different vegetables and fruit samples comprising of Pawpaw and Scent leaves were digested and analyzed for heavy metals using Flame Atomic Absorption Spectrophotometer (F-AAS).

Results: The result of the present study reviewed that Pb, Cd, Ni, and Zn ranged from 1.090 ± 0.01 - 5.990 ± 0.06; 0.213 ± 0.03 - 1.317 ± 0.02; 2.810 ± 0.04 - 4.767 ± 0.09; and 0.793 ± 0.01 -5.303 ± 0.02 mg/kg, respectively. The concentrations of Pb, Cd, and Ni in some of the analyzed pawpaw and scent leaf samples exceeded the permissible limit as recommended by WHO/FAO, EC/CODEX and NAFDAC respectively. The concentrations of Zn were below the permissible limit as recommended by WHO/FAO. The Estimated Daily Intake (EDI) of Pb and Cd exceeded the oral reference dose (RfDo) however; Ni and Zn fall within the oral RfDo. The Target Hazard Quotient (THQ) and Hazard Index (HI) values of Pb, Cd, Ni and Zn were less than 1. The Carcinogenic Risk (CR) of Cd and Ni exceeded the range of permissible predicted lifetime risks for carcinogens as recommended by US EPA, meanwhile, the carcinogenic risk of Pb was within the permissible predicted lifetime risks as recommended by USEPA.

Conclusion: The result from the present study indicate that the fruits and leaves from pawpaw and scent leaf may be contaminated with Pb, Cd, and Ni and the exposed population may be at risk of developing cancer due to carcinogenic ingestion of Cd and Ni over time.