Metal pollution and human health risk assessment of soils and edible plants in farmlands around Enyigba lead-zinc mining site, Ebonyi State, Nigeria

摘要

This study evaluated the level of metals in edible plants, their chemical forms in the soil, and the associated health risk in Enyigba lead-zinc mining vicinity in Ebonyi State, Nigeria. Soil sample, Telfairia occidentalis and Amaranthus hybridus were collected from mining sites (Ishiagu-Enyigba and Elinwobvu-Enyigba) and non-mining site (Ekawoke-control) and analyzed using standard protocols. The results showed that a high percentage of Cd, Pb, Fe, and Zn were associated with non-residual fraction, while Cu, Cr, and Ni were bounded with residual fraction. The order of mobility and bioavailability of the metals was as follows: Pb Cd Fe Zn Cr Ni Cu. Geoaccumulation index (I-geo) indicated moderate to strong pollution of the mining sites with Cd Cu, Pb, and Zn. The most significant contributor to hazard index (HI) was ingestion of edible plants; followed by ingestion, dermal-contact, and then inhalation of soil particles. HI values for Cd (1.32), Cr (1.05), and Pb (1.97-2.04) for children in the sites exceeded United States Environmental Protection Agency (USEPA) safe limit (HI 1). Total cancer risk (TCR) for adults and children via soil inhalation or soil ingestion were below USEPA safe limit (TCR 1.0 x 10(-4)). TCR for adults and children via consumption of T. occidentalis or A. hybridus exceeded USEPA safe limit (TCR 1.0 x 10(-4)). These results strongly indicated associated noncarcinogenic and carcinogenic health risk of these metals from the soil and the edible plants around Enyigba mining sites vicinity to humans especially children, this calls for concern.