Fluoride is the stuff in toothpaste that helps strengthen teeth. But if there's too much fluoride in the water it softens bones, and children become susceptible to bone deformities. It's very difficult and expensive to remove dissolved fluoride ions from water. But, inspired by nature, scientists have used polymers to produce a membrane that can filter out fluoride, as Sally Le Page heard from Ayse Asatekin... Like this podcast? Please help us by supporting the Naked Scientists