Assessment of human exposure to food crops contaminated with lead and cadmium in Owerri, South-eastern Nigeria

•Pollution resulting from urbanisation influences metal concentrations and release of toxic elements in the food chain.•Concentrations of Cd and Pb in soil, pumpkin leaves and cassava tubers were above regulatory guidelines.•Elevated Pb in plant leaves showed no correlation with soil parameters suggesting source from atmospheric deposition.•Body weight influences human susceptibility to metal toxicity in food plants with children estimated as most vulnerable to metals in food crops.