Dirty girl

This weekend we were at our friends' (Mark and Sharon's) place when we looked over and caught Mason eating dirt from one of the flower pots. Is dirt so bad? I know that when I was a kid I ate dirt and I'm pretty sure that Ann did too. Are we too clean in the Western World? Has cleanliness led to the increase in asthma, allergies or even insulin-dependent diabetes? I'm not sure, but just to be safe, from now on I'll be ensuring Jacob and Mason eat a pound of garden dirt every day.