Concentration and Health Risk of Heavy Metals in Herbs from Electronic Waste Disposal Site in Lagos State, Nigeria

Abstract

Considering that about 80 % of the world population uses herbs for the treatment of illnesses and the contamination that is prevalent at electronic waste (e-waste) disposal sites, this study evaluated the concentrations of heavy metals and health risks in the use and consumption of Rhynchospora corymbosa, Pentodon pentandrus and Cyclosorus dentatus, herbs commonly found in electronic waste disposal site in Lagos State, Nigeria using appropriate standard methods. The mean concentrations of the heavy metals in the plant were: 100.78±0.91, 0.16±0.02, 25.68±0.44, 258.94±1.62, and 8.51±0.04 mg/kg for Pb, Cd, Ni, Cu and Cr, respectively. Pentodon pentandrus had the highest Pb, Cu and Ni concentrations, Cyclosorus dentatus had the highest Cd concentration while Rhynchospora corymbosa recorded the highest concentration of Cr. The bio-accumulation factor of Cu in Pentodon pentandrus and in Rhynchospora corymbosa and of Cr in Rhynchospora corymbosa were higher than 1. The estimated daily intake of Pb and Ni in Pentodon pentandrus, Cyclosorus dentatus and Rhynchospora corymbosa exceeded the Provisional Maximum Tolerable Intake, indicating an intolerable risk to the consumers’ health. The hazard index of each of the plants indicates that the cumulative health effects of the heavy metals would cause potential health hazards to the consumers.  This useful information gives an accurate indication of the levels of contamination of the plants and the potential health risk effects of the consumption of these herbs from the dumpsite.