How were the kids in this town contaminated?

For children in Port Pirie there is no 10 second rule. When you grow up in a “lead town” eating off the floor is forbidden, and could be harmful to your health. But when a mum follows all the strict and unusual rules of the town to keep her son safe and his blood lead still continues to rise, she asks: what am I doing wrong? Can a town coexist with a lead smelter? Paul Culliver investigates