One of catches that I can think of is a danger of swallowing a couple of them. For example, there is a special regulation regarding small magnets in objects tha

One of catches that I can think of is a danger of swallowing a couple of them. For example, there is a special regulation regarding small magnets in objects that children can access. If they cling inside a body through some tissue, one will need a very nasty emergency surgery. It's not made easier by the fact that most surgical instruments are made from steel.