Heavy Metal Accumulation in Soils and Vegetables in the Vicinity of a Cement Factory in Benue State

This study investigates the accumulation of heavy metals in soils and vegetable crops near a major cement manufacturing facility in Benue State, located in Nigeria's North Central geopolitical zone. Cement production is a significant source of dust and emissions containing heavy metals including lead, cadmium, chromium, nickel, and zinc, and communities adjacent to cement plants face potential health risks from soil contamination and dietary exposure through locally grown vegetables. Using a distance-gradient sampling design, surface soil samples (0 to 15 cm) and paired vegetable samples (Amaranthus and Telfairia) were collected at distances of 0.5, 1.0, 2.0, 3.0, and 5.0 km from the factory in prevailing downwind and upwind directions. Samples were digested and analysed by atomic absorption spectrophotometry. Bioconcentration factors and daily intake estimates were calculated for each metal. Findings revealed that soil lead and chromium concentrations at 0.5 km downwind exceeded Nigerian Federal Environmental Protection Agency guidelines by factors of 4.2 and 2.8 respectively. Vegetable bioconcentration of chromium was significant in Amaranthus at 0.5 and 1.0 km from the factory. Daily dietary intake estimates for adults consuming these vegetables at the 0.5 km zone exceeded FAO/WHO tolerable intakes for both lead and chromium. Contamination significantly declined with increasing distance and was markedly lower upwind. The study recommends prohibition of vegetable cultivation within 1.0 km downwind of the facility and regular soil and crop monitoring at buffer zones. Keywords: heavy metals, cement factory, vegetable contamination, Benue State, bioconcentration.