Rusty nails in and of themselves are not what causes the tetanus toxin to flare up in a wound. Feces from livestock in barnyards (barnyard nails) and in farm soil are where the toxin is found prolifically. My younger friends fear rust of any type, erroneously believing that rust alone carries tetanus. Rust is iron oxide and won't hurt you. Shallow wounds that receive air (oxygen) won't likely lead to tetanus; tetanus require anaerobic (oxygen-less) wounds in which to flourish. Deep wounds. I am not a doctor. I just read a lot. I think "they" are trying to scare everyone into yet another "required" vaccine these days.