I sometimes worry about the personal information stored inside my phone - but I didn't realise so much could be identified about me from what's on the outside.
Scientists have tested traces found on adults' mobile phones, revealing a lot about them - from the type of cosmetics they use, to what they like to eat and drink, and medical conditions. Caffeine, spices, antidepressants and skin creams were some of the substances found.
I think this could be really useful. But it's also a bit scary, as so much personal information could be revealed this way.