Evaluation of Heavy Metals Content and Human Health Risk Assessment via Consumption of Vegetables from Selected Markets in Bayelsa State, Nigeria

Abstract

The aim of this study was to evaluate the concentration of heavy metals namely (Lead (Pb), Nickel (Ni), Cadmium (Cd) and Chromium (Cr)) via consumption of vegetables from selected markets in Bayelsa State, Nigeria. Sixteen different vegetable samples comprising of Bitter leaves (Vernonia amygdalina), Curry leaves (Ocimum basilicum), Scent leaves (Ocimum gratissmum), Water Leaves (Talinum triangulare), Uziza (Piper guineese), Fluted pumpkin (Telferia occidetalis), Okazi (Gnetum africanum), and Okra (Abelmoschus esculentus) were digested and analyzed for heavy metals using Solar Thermo Elemental Flame Atomic Absorption Spectrophotometer (STEF-AAS). Results obtained were used to estimate the health risk of these heavy metals via consumption of the vegetable samples. The results from the study showed that the heavy metal concentration ranged between 0.016 to 1.387 mg/kg, 0.028 to 1.487 mg/ kg, 0.093 to 3.625 mg/kg and 0.893 to 2.478 mg/kg for Pb, Cd, Ni and Cr respectively. The concentration of Pb was below permissible limit recommended by WHO/FAO. The concentration of Cd in O. gratissimum and T. triangulare from both markets exceeded the permissible limit recommended by WHO/FAO and EC/CODEX. The concentration of Ni in O. gratissimum and T. occidetalis from Kpanshia market exceeded the permissible limit recommended by NAFDAC while Cr from both markets exceeded permissible limit recommended by European community/CODEX. The Hazard Index (HI) values for all the samples under study were greater than (>) 1 which indicates that there is potential health risk to those consuming these vegetables except A. esculentus in Kpanshia market for adults which was less than (<) 1. The Target Hazard Quotient (THQ) concentrations of Pb in O. gratissimum, T. occidetalis and G. africanum from Kpanshia market and O. basilicum from Swali market, Cd in T. triangulare and O. gratissimum from both markets and Ni in T. occidetalis from Swali market for children only were all greater than 1 which indicates level of concern that the population may be at risk of either Pb, Ni or Cd toxicity. The Estimated Daily Intake (EDI) concentrations of Pb in O. gratissimum, T. occidetalis and G. africanum all from Kpanshia market, Cd in T. triangulare from both markets, and Ni in all the samples from both markets were all above the permissible tolerable daily intake (PTDI) limit as recommended by EFSA (European Food and Safety Agency) meaning that those who consume this product may be at risk. The results from the present study tends to suggest that consumption of vegetables from both markets under study in Bayelsa state could be one of the contributory factors to the heavy metal burden among consumers due to their frequent consumption.