It's worth noting that they can literally kill you if you eat more than one of them, although you'd probably have to not eat them quite at the same time. The magnetic force between them is strong enough they could pinch two sections of your intestines together and they'd be unremovable without surgery.
That said, I gave my nephew a set when he was 11 or 12. Told him and his parents what the deal was, they said it was OK. My brother's really into guns, so as long as you know and follow safety rules, he's OK with having things around that can kill you.
