Empirical Analysis of Heavy Metal Accumulation in Soils and Crops Near Industrial Estates in Ogun State, South West Nigeria

Soil contamination by heavy metals near industrial estates poses risks to food safety, ecosystem integrity, and human health through dietary exposure. This study conducted an empirical analysis of heavy metal accumulation in soils and crops cultivated near the Sango-Ota Industrial Estate, Ogun State, South West Nigeria. Soil samples were collected from forty-eight plots at three depth intervals, and edible crop samples including leafy vegetables, tubers, and maize were collected from farms within one kilometre of the estate boundary and from reference farms three kilometres distant. Concentrations of lead, cadmium, chromium, nickel, and zinc were determined using inductively coupled plasma mass spectrometry. Contamination indices, including geo-accumulation index and enrichment factor, were computed to assess the degree of anthropogenic influence. Results showed significantly elevated concentrations of lead, cadmium, and chromium in soils within the industrial proximal zone compared to reference sites. Cadmium concentrations in leafy vegetables from industrial-proximal farms exceeded the European Union maximum permissible limits for food. Bioconcentration factors calculated for leafy vegetables indicated preferential cadmium accumulation in plant tissues. The incremental cancer risk from dietary exposure to chromium exceeded the acceptable risk threshold for adults consuming locally grown vegetables. The study fills a critical research gap by quantifying crop-specific metal transfer from contaminated soils in the Nigerian industrial context. Recommendations include soil remediation, crop restriction policies, and regular food safety surveillance near industrial estates. Keywords: heavy metals, soil contamination, industrial estates, bioaccumulation, dietary exposure.