I wouldn't worry about kids. They're fairly smart.
It's really stupid adults I would be worried about....
(Seriously, avoiding a direct answer? They're made of metal and they appear to have some edges. Common sense would dictate not rolling them in your eye sockets... and would further suggest that the d4 is a military-grade caltrop. However, as they were custom made for an adult - who presumably has a clue - I don't think you need to worry that there is a new dangerous toy on the market threatening the safety of your eyeballs.)