Science Questions with Surprising Answers
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Dr. Christopher S. Baird

How long can you wait after dropping food on the ground to eat it without having germs attached? Some say it's a five-second rule, others say ten.

Category: Health      Published: December 14, 2012

By: Christopher S. Baird, author of The Top 50 Science Questions with Surprising Answers and Associate Professor of Physics at West Texas A&M University

SEM of Salmonella
Scanning Electron Microscope (SEM) image of Salmonella bacteria. Public Domain Image, source: CDC.

Germs immediately attach to food dropped on the floor. They don't have to wait five seconds to do anything. Germs are very sticky creatures; as soon as your food touches the floor, the germs stick, according to research done by P. Dawson as reported in the Journal of Applied Microbiology. Dawson further found that significantly more bacteria is transferred to food dropped on wood and tile floors than on carpet. With that said, germs aren't just things that exist only on the floor. Germs are everywhere. If you took the tip of your average pencil and looked at it through an electron microscope, you would see a zoo of germs. Germs include bacteria, viruses, and fungi, as well as microscopic animals such as dust mites. They live everywhere: in your pillow, on your finger, in your hair, and in your stomach. Most of these germs are rather harmless. Additionally, the ones that are dangerous have to get past your skin to do any damage. That's why cuts should be treated to minimize infection, and why surgery is a sterile environment. Another way germs can get in is through your mouth. That's why it is not a good idea to eat food off the floor no matter how long it has been sitting there.

Topics: 10 second rule, dropped food, food, germs