Hmm, I was going to guess antimony, I know it's poisonous, but not sure it causes paralysis.

I'm gonna guess nickel

cast steel, wrought iron, or cast iron (though less used due to its brittleness) are the main metals that anvils are made from. as for paralyzing if you inhale it... a good galvanized metal (in this case steel) can knock you on your ass if you weld without a respirator on. as for anything else, you have to start getting into the exotic metals to start getting into a side effect like paralysis. If that is the case most anvils will not contain such exotic metals.

Manganese is the metal mixed with low carbon steel, you inhale it your nevous system will tweek!