Lead is the sweetest of poisons, blamed for everything from mad Roman emperors to modern-day crime waves. Yet a lead-acid battery is still what gets your car going in the morning. So have we finally learnt how to handle this heavyweight element? Justin Rowlatt travels to arts shop Cornelissen in London's Bloomsbury to find out why they have stopped stocking lead paints, and hears from professor Andrea Sella of University College London about the unique properties that have made this metal so handy in everything from radiation protection to glassware.

Yet lead in petrol is also accused of having inflicted brain damage on an entire generation of children in the 1970s, as the economist Jessica Wolpaw-Reyes of Amherst College explains. And, producer Laurence Knight travels to one of the UK's only two lead smelters - HJ Enthoven's at Darley Dale in Derbyshire, the historical heartland of the UK lead industry - to see what becomes of the lead in your car battery. And, we speak to the director of the International Lead Association, Andy Bush. Show less