What is Cross Contamination? - Definition, Examples & Facts

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson is going to define cross-contamination. You'll learn a few facts about this topic before going over numerous examples of how cross-contamination might occur in daily life.

What Is Cross Contamination?

You've probably heard that you shouldn't use a cutting board used for meat in order to also chop up vegetables and fruit. But do you know why? If you answered that it's because you don't want to spread germs around, or something similar, you're absolutely right! More technically, we call this cross-contamination.

The transfer of an agent of illness or disease from one individual or site to another is known as cross-contamination. This term is often used specifically to refer to the transfer of pathogenic (disease-causing) bacteria from one object or person to another, especially in a food-related setting.

Let's learn a few facts about and get examples of cross-contamination in that light.


If your kitchen counter looks clean, is it really? The fact is, looks can be deceiving. Just because a kitchen countertop looks clean to the naked eye doesn't mean it is free from potentially dangerous bacteria like E. coli.

How about that dishcloth? It looks clean. You even washed it in some lukewarm water. So it's clean, right? Nope. Fact is, rinsing a dishcloth is not enough to remove the bacteria. Even antibacterial soap isn't enough to properly clean the cloth because that kind of soap doesn't kill potentially dangerous viruses.

And what about those clean hands? You just washed them with soap. They're clean, right? Again, no. The reality is that washing your hands might only spread germs around on your hands instead of washing them off if you don't wash them thoroughly enough.

If you don't clean your kitchen countertop, dish cloths, and hands, you can transfer (cross-contaminate) other objects!

Here are some other important facts about cross-contamination:

  • Even the edible portions of fruits and vegetables can be contaminated with germs. For example, if you're slicing a watermelon, that knife can cross-contaminate the inside of the watermelon by carrying germs from the rind.
  • You need to clean your refrigerator to prevent cross-contamination. The cold temperature doesn't kill all kinds of viruses and bacteria, so they can easily contaminate the surfaces of the fridge - surfaces that will contact other things you'll later put in your mouth!
  • Cleaning produce, including anything produce touches, is just as important as cleaning anything that meat products touch. Produce can have lots of bacteria and viruses on them as well!
  • Freezing your food may not save you from disease! Many viruses can survive freezing temperatures. So that hunk of frozen meat? Yep, it can still carry dangerous germs, so you'll still need to wash any surface it comes into contact with.


At this point, you probably have a pretty good idea of the many ways by which cross-contamination can occur, but let's go over some other specific examples of cross-contamination.

If you use a knife to slice some meat and then use that same knife on produce without washing it in between, you can cross-contaminate the meat and produce.

Or, let's say you used a dishcloth to wash a cutting board used for meat. Then, you use that same dishcloth to wipe down the kitchen countertops. Bad idea! You've just transferred germs from the cutting board onto your kitchen countertops.

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