Roadside cultivation – a heavy metal health hazard?

Nearly three-quarters of Ugandan vehicles are found in Kampala. Most run on leaded petrol, and each morning and evening the city's main arteries bear a steady stream of traffic. In such an environment, when Kampala City Council took the decision, in 2003, to legalise urban agriculture, they faced a hostile media reaction. How could crops grown in such polluted air be safe to eat?