Pennies minted before 1982 are all copper (so go ahead, give him a bowlful!), but after that they started putting zinc into the mix. Zinc gives babies stomach ulcers. Isn't that nice. And the trouble with dirt, around here anyway, is that raccoons are always shitting in it, and if your baby gets a mouthful of raccoon poo he might end up with raccoon roundworm. There is no cure for raccoon roundworm, either your baby will survive it or he won't, and if he does survive he'll probably be blind and brain damaged, and your heart will be broken in two. So watch the pennies and the dirt, okay?