"Mom, why are Owen's teeth blue"?

So I'm in the kitchen this morning baking my favorite cookies. Caitlin is sitting at the kitchen table working on her crafts, and Owen is playing with his blocks on the ground...or so I thought. Caitlin must have dropped a crayon, and Owen thinks everything belongs in his mouth. Obviously it took a while for us to notice (and by 'us', I mean Caitlin) because his mouth wasn't just a little blue, it was very blue. Oh, kids...I need a cup of tea.