‘Rust causes tetanus infection’

This is an old wives’ tale. Tetanus is caused by a bacterium called Clostridium tetani. These bacteria thrive in dirty, airless environments.

When metal rusts dirt may begin gathering in rusty places and harbour clostridia. When they enter the body, usually through a deep injury, they may cause tetanus. However, as Clostridium tetani lives in dirt you can get tetanus with a penetrating injury from any dirty object, not just a rusty nail.