10yo DS and loads of his friends at school are obsessed with Sharpie pens at the moment - nothing sinister, they're not sniffing them or anything, just using them like ordinary felt tips. They all have big sets, and swap different colours with each other, so much like any other craze.
Except, they're not ordinary felt tips, the fumes from them are really strong. DS has had a few headaches over the last week and today it suddenly occurred to me that it could from drawing and writing for long periods with the Sharpies, indoors at close range. Have had a search online and can't find any strong evidence either way but lots of suggestions that it's not a good idea. I have told him today to use them less and to be more aware. Any thoughts?