Heavy Metal Contamination, its Transfer from Dumpsite Soils to Vegetables and its Risk to Human Health in Benin City, Nigeriaa

Abstract

The indiscriminate location of dumpsites within residential areas and the consumption of vegetables cultivated around such placement poses significant environmental and public health concerns. This study investigated heavy metal contamination in soil and vegetables (Amaranthus hybridus) cultivated around three selected dumpsites from December 2021 to February 2022 to determine the level of metal contamination and assess potential human health risks associated with vegetable consumption. Soil and vegetable samples were collected and analysed for heavy metals using Atomic Absorption Spectrophotometer (PG Instruments AAS 500F). Heavy metal concentrations differed significantly among the sampling station (p < 0.05) with Pb and Cu showing elevated levels at some locations. The Transfer Factor (TF) values indicated exceptionally high Fe accumulation (8.15) at station 1, while Mn exhibited a high TF value at station 3 (1.28). Hazard Quotient (HQ) values revealed variations in metal-specific contributions to non-carcinogenic risk between children and adults, while Hazard Index (HI) values exceeded the acceptable limit of 1 across all sampling locations, indicating potential non-carcinogenic health risks from prolonged exposure. The Cancer Risk Factor (CRF) and Cumulative Cancer Risk Index (CRI) indicated that Cd was the major contributor to carcinogenic risk. These findings demonstrate that consumption of vegetables cultivated around dumpsites may pose significant non-carcinogenic and carcinogenic health risks, particularly to children, underscoring the need for stricter waste management and routine monitoring of food crops.