Ask the Naked Scientists, South Africa 13.02.01 - Why Tired Toddlers Rub Their Eyes

Summary: 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...