What Is Cross Contamination and How Can You Avoid It?

It’s not your imagination: There have been lots of food recalls in the past few years. Cross contamination is responsible for empty shelves in grocery stores around the world.

But what exactly is cross contamination? And how can you keep yourself and your family safe? We asked pediatric infectious disease specialist Frank Esper, MD.

What is cross contamination?

Cross contamination happens when an object with allergens, toxic materials or illness-causing microbes like bacteria or viruses touches (and contaminates) something or someone else. You can use the term “cross contamination” to describe a wide range of situations. But we often use it to talk about food safety.

How it happens

Cross contamination can happen in many ways for many reasons, but poor sanitation and food handling practices usually play a role. It’s one of the tactics germs use to move from place to place and person to person.

Dr. Esper explains that food can become cross contaminated at any time.

“It could happen anywhere from farm to table,” he says. “Many major players in the food processing industry have merged, so there are only a few distributors responsible for many states, if not entire regions. That’s why, when you hear about an outbreak of a foodborne illness, it’s usually across multiple states, grocery stores or restaurants.”

The same is true of food allergens.

“The particles from, for example, a peanut, can move within the environment, leading to cross contamination,” Dr. Esper explains. “So, you can have an allergic reaction, even though nobody in the production process worked directly with peanuts.” That’s why packaged foods note if they’re made in a facility that also makes products with common allergens.

Cross contamination can also happen in your kitchen, when you touch a contaminated surface or food and don’t wash your hands.

“We, as humans, tend to use our hands a lot,” he continues. “And when our hands come into contact with our mouths and eyes, germs can get in.”

Health risks

Cross contamination is a common source of food poisoning, foodborne illnesses and allergic reactions. The germs that get into your food are usually bacteria like:

• Salmonella
• E. coli
• Listeria

The following signs could mean that something you ate was contaminated by bacteria:

• Stomach pain or cramping
• Nausea and vomiting
• Diarrhea
• Headache
• Fever
• Fatigue

If you have a food allergy, cross contamination can cause anything from a mild itchy mouth to a severe allergic reaction called anaphylaxis. Minor symptoms can be managed with an over-the-counter antihistamine. But if you have a history of severe allergies or anaphylaxis, keep an EpiPen® on hand when making and eating meals.

How to prevent cross contamination

There’s no way to completely avoid cross contamination — it often happens long before you pick out your groceries or order a meal. But there are things you can do to reduce the risk of it happening in your kitchen. Dr. Esper shares some tips to cut down on the risk of cross contamination.

• Wash your hands. Scrub your hands for 20 seconds with warm water and soap before, during and after handling food. And wash them again if you go to the bathroom, change a diaper, snuggle your pet or handle pet food.
• Clean as you go. “When you’re preparing raw meat, poultry or seafood, you have to assume that your cutting board and utensils are contaminated,” Dr. Esper advises. Don’t use them on other foods. And don’t serve anything with them until they’ve been sanitized.
• Consider having dedicated cutting boards. The U.S. Department of Agriculture (USDA) Food Safety & Inspection Service recommends having one cutting board solely for use on animal proteins and a separate one for fruits, veggies and bread.
• Separate raw and cooked groceries. Packages of raw meat, fish or poultry should get a dedicated bag. If you use reusable bags, clean and sanitize them in-between uses.
• Monitor meat temperatures. Learn the minimum internal temperatures for every type of meat you cook. And don’t forget to clean your meat thermometer after every use!
• Don’t wash raw poultry or meat. As long as you’re cooking your food at the proper temperature, you don’t need to worry about germs surviving. And while it may seem like a good idea, don’t wash meat or poultry. It can spread germs around your kitchen.
• Wash kitchen items thoroughly. This goes for anything you use on a regular basis, like utensils, dishes, appliances and more.
• Replace sponges at least every other week. Sponges are primo real estate for germs. Throw them out if they’re looking (or smelling) even a little gnarly.
• Wash kitchen towels at least once a week. And always swap out dish cloths that are dirty or stinky.
• Disinfect all surfaces. Dr. Esper is a fan of soap or alcohol-based cleansers. “Bacteria are surrounded by a cell wall,” he explains. The reason soaps and alcohol-based products work so well is that they blow open that cell wall, which kills the bacteria.”
• Store food carefully. Store leftovers and readymade foods in the top section of your fridge or freezer. Keep raw foods in the lower level. Meat, fish, eggs and poultry should always be in a tightly sealed container to prevent leakage.
• Clean out your freezer every few months. “Freezing food doesn’t make it sterile,” Dr. Esper clarifies. “Bacteria may not grow as fast on frozen foods, but they’ll grow if you leave something in there long enough. There have been listeria outbreaks involving ice cream, for example.”

Final thoughts

If, despite your best efforts, you contract a foodborne illness or experience food poisoning, it can be miserable. But it should get better on its own. Call a healthcare provider if your symptoms are severe, get worse with time or last more than two days. You may need IV fluids or prescription medication.

Foodborne illnesses pose a greater risk for certain people. Call a provider as soon as you notice symptoms if:

• You’re over age 65.
• A child under 5 is affected.
• You have a chronic illness.
• You’re pregnant.
• You’re immunocompromised.