Don't swallow nickels

[snopes]

Comment: i received an e-mail the other day for parents. it said that when
children swallow coins they are usually ok, EXCEPT for nickels? that
nickels after a certain year can kill them if swallowed? is this true? or
just another parent scare tactic?

A quick search of the metal composition of your every day coin shows that, while dimes, quarters, and half-dollars are overwhelmingly copper (~90%+ copper, ~9% nickel), Nickels contain exactly 25 percent nickel. Origin of the myth? Maybe. Dangerous? Probably not.

However, looking a little deeper shows that during WWII, nickels contained approximately forty percent copper, forty percent silver, and 9 percent manganese, which might be our culprit, since it is used in some pesticides (maneb). Still, don't think it's more dangerous than any other coin, as copper is far more dangerous, ingesting more than ten milligrams per day can cause toxic shock. But coins aren't exactly easily digestible.