Reprinted with permission of McGill University's Office for Science and Society. The original article can be found here.
Ever step on a rusty nail? It was, in all likelihood, rapidly followed by your parents dragging you to the doctor’s office for a painful (but safe!) tetanus shot. The memory of my first tetanus shot is preceded by an exploring an abandoned barn and getting cut by a stray wire fence. If it had happened in my own home it wouldn’t have even deserved a band-aid, but the threat of rust sent us to the doctor's office.
But it turns out that injuries caused by rusty objects aren’t any worse than injuries caused by any other discarded object.
Tetanus, or lockjaw, is a bacterial infection caused by Clostridium tetani, an extremely hardy rod-shaped bacterium found in animal digestive tracts and soil worldwide. Tetanus is fatal in about 10% of cases but causes muscle spasms, fever and trouble swallowing in all cases.
The reason we associate tetanus with rust is because it’s often found in soil that’s rich in organic material like manure or dead leaves. Old houses, cars or other discarded items left in nature for long enough will rust (if they’re metal) and collect bacteria like Clostridium tetani, but the relationship between rust and tetanus-causing bacteria is purely correlative, not causative. Humans can be exposed to Clostridium tetani in a variety of non-rusty ways, such as when cleaning animal cages, when bitten by infected animals, or if exposed to contaminated heroin.
So if your skin is pierced from anything from your own kitchen knife to a rusty gnarled screw, or if you begin working on a farm, it's worth making sure that your tetanus shot is up to date. After all, (in Canada at least) it's free and lasts an entire decade.