Are helium-filled balloons less likely to pop? How does a cordless toothbrush charge? Is there much mercury in compact fluorescent bulbs? Why do tired toddlers rub their eyes? Is lactose intolerance more common than it once was? And is it possible to trigger earthquakes artificially? Dr Chris answers this week's burning questions on Talk Radio 702, South Africa... Like this podcast? Please help us by supporting the Naked Scientists