Cross-Contamination

Cross-contamination is the transfer of harmful bacteria to food from other foods, cutting boards, and utensils and it happens when they are not handled properly. This is especially true when handling raw meat, poultry, eggs, and seafood, so keep these foods and their juices away from already cooked or ready-to-eat foods and fresh product.

Hand washing after handling raw meat or poultry or its packaging is a necessity because anything you touch afterwards could become contaminated. In other words, you could become ill by picking up a piece of fruit and eating it after handling raw meat or poultry without properly washing your hands.

Wash hands with water and soap for 20 seconds before and after handling food; before eating; and after using the bathroom, changing diapers, tending to a sick person, blowing your nose, sneezing, coughing and handling pets. You should also wash your hands after touching surfaces that are frequently used, like doorknobs and handles, light switches, phones and keyboards.

In USDA observational studies, participants did not attempt to wash their hands up to 75 percent of the time when it was required. When handwashing was attempted, participants failed to follow the CDC recommended steps for handwashing up to 99 percent of the time. The most common errors were not scrubbing their hands for 20 seconds, followed by not wetting their hands with water before applying soap.

Packaging materials from raw meat or poultry also can cause cross-contamination. Never reuse them with other food items. These and other disposable packaging materials, such as foam meat trays, egg cartons or plastic wraps, should be discarded immediately after you have removed their contents.

Minimize the Risk: Clean and Then Sanitize Surfaces and Sinks

It is important to prevent cross-contamination from raw meat or poultry juices and other contaminants by washing countertops and sinks with hot, soapy water. For extra protection, you should also sanitize utensils and disinfect surfaces with solutions that can eliminate illness-causing germs. If using commercial sanitizers or disinfectants in your kitchen, choose ones that are approved for your kitchen surfaces and follow the manufacturer’s instructions to use each product safely and effectively.

1. Clean FIRST.

Cleaning physically removes dirt, debris and some bacteria that can cause illness, including foodborne illness, from your kitchen, but it does not kill germs. To clean your utensils, cuttings boards, surfaces and even the kitchen sink, use warm, soapy water to wash them. Air dry or wipe clean with single-use or paper towels. If you use kitchen towels for cleaning, they should be washed frequently using the hot cycle of the washing machine.

Foodborne illness-causing bacteria can remain on surfaces for a very long time. Campylobacter can survive in your kitchen for up to 4 hours and Salmonella can last for up to 32 hours. Norovirus, often called the stomach flu or a stomach bug, is the most common foodborne illness-causing germ in the United States. Norovirus is a very contagious virus that causes vomiting and diarrhea. It can spread easily if you eat or drink contaminated food or touch contaminated surfaces or objects then put your unwashed hands in your mouth.

2. THEN Sanitize

Sanitizing and disinfecting can kill germs and foodborne illness-causing bacteria in your kitchen, but this is most effective after you have cleaned. Many different sanitizers or disinfectants can be used, but make sure any commercial products you choose are safe for the food contact surfaces in your kitchen before you use them.

Use Sanitizers for Cutting Boards and Utensils

Only use sanitizing products that are intended for use on cutting boards or utensils that touch food. An easy, food-safe homemade sanitizer for cutting boards, knives and other utensils that directly touch food can be made by mixing a solution of one tablespoon of unscented liquid chlorine bleach with a gallon of water. To sanitize utensils and cutting boards after cleaning, pour sanitizing solution on the cutting boards and let it stand for several minutes or use it as a soak for your utensils. Next, rinse them with clean water and air dry or pat them dry with clean towels.

If using commercial sanitizers, make sure they are approved for use on cutting boards or utensils before using for this purpose. Follow the manufacturer’s instructions on the label for safe use. Some commercial sanitizers may require utensils to be rinsed after use.

Your dishwasher can also effectively clean and sanitize your utensils and cutting boards if they are dishwasher safe and are made of materials that are non-porous (e.g., acrylic, plastic, glass and some solid wood boards without cracks or scratches).

Use Disinfectants for Surfaces, Countertops and Sinks

Disinfecting products, unlike some commercial sanitizers, should not be used on cutting boards or utensils that touch food because they could contaminate the food you prepare. However, disinfectants are safe to use on surfaces and high touch areas in order to destroy bacteria.

According to the CDC, a homemade disinfectant for surfaces can be made by mixing a solution of five tablespoons (one-third cup) of unscented liquid chlorine bleach to one gallon of water or four teaspoons of bleach per quart of water. You should use gloves to protect your hands before using disinfectant solutions. Pour or spray your homemade disinfectant on sinks, countertops and other surfaces, then let it sit for at least one minute before wiping your surfaces clean with a paper towel. Be sure they are completely dry before using those surfaces or your sink again.

If using commercial disinfectants, make sure they are approved for use on your surfaces and completely follow the manufacturer’s instructions on the label. Some commercial disinfectants may require your surfaces to be rinsed with clean water after use.

After cleaning and then sanitizing or disinfecting anything in your home, make sure to wash your hands with soap and water for 20 seconds.

Washing Meat and Poultry

Many consumers wash or rinse their meat or poultry before cooking it. Washing meat or poultry can mean different things to different people: some consumers rinse it under running water or with a strainer, others soak it in containers full of water and some even use saltwater, vinegar or lemon juice to try to “clean” their meat. However, washing raw poultry, beef, pork, lamb or veal before cooking it is not recommended. Bacteria in raw meat and poultry juices can be spread to other foods, utensils and surfaces. We call this cross-contamination.

While washing meat and poultry to remove dirt, slime, fat or blood may have been appropriate decades ago when many slaughtered and prepared their own food, the modern food safety system doesn’t require it. Meat and poultry are cleaned during processing, so further washing is not necessary. Never use soaps or detergents on your meat or poultry products. They can contaminate your food with chemicals and make it unsafe to eat.

Some consumers may wash or rinse their raw meat or poultry because it’s a habit or because a family member they trust has always washed their meat. USDA research found that washing or rinsing meat or poultry increases the risk for cross-contamination in the kitchen, which can cause foodborne illness.

If you wash meat or poultry, some bacteria can be splashed on the surfaces of your kitchen. Failure to clean and sanitize these contaminated areas can lead to foodborne illness. Cooking to the right temperature (whether frying, baking, broiling, boiling or grilling) kills germs on meat and poultry, so washing these products is risky and not necessary for safety.

Using a food thermometer is the only sure way of knowing if your food has reached a high enough temperature to destroy germs, including foodborne illness-causing bacteria.

• Cook all raw beef, pork, lamb and veal (steaks, roasts and chops) to a minimum internal temperature of 145°F. For safety and quality, allow meat to rest for at least three minutes before carving or consuming.
• Ground meats are safe to eat at 160°F. For burgers, insert the food thermometer in the side of patties until it reaches the center for an accurate reading.
• Poultry products, including whole, parts or ground chicken or turkey, are safe to eat at 165°F.
• Cook fish and seafood to 145°F or until the flesh is opaque and flaky.

For reasons of personal preference, consumers may choose to cook meat to higher temperatures.

Soaking Meat and Poultry

Callers to the USDA Meat and Poultry Hotline sometimes ask about soaking meat or poultry in saltwater or about using a brine solution. This is a personal preference and serves no purpose for food safety. If you choose to do this, however, preventing cross-contamination when soaking and removing the meat or poultry from the liquid is essential. Carefully pour out the soak and do not reuse it. Wash the container you used for the soak or sanitize it in the dishwasher. Clean and then sanitize your inner sink and any surfaces that touch the used soak. Meat or poultry should be kept in the refrigerator while soaking.

Sometimes consumers rinse or soak country ham, bacon or salt pork because they think it reduces the sodium or salt enough to allow these products to be eaten on a sodium-restricted diet. However, very little salt is removed by washing, rinsing or soaking a meat product and doing so is not recommended.

USDA’s Poultry Washing Study

USDA conducted a study where we observed the actions of individuals who self-reported washing or rinsing raw poultry when cooking at home. These participants gave many reasons for why they wash or rinse poultry, including to remove slime, skin, fat or blood (30 percent); out of habit (28 percent); because a family member has always done it (19 percent); or to remove germs or bacteria (19 percent).

Participants were observed while cooking chicken thighs (spiked with harmless tracer bacteria that behave like Salmonella) and preparing a mixed green salad to determine whether they washed their poultry, the extent of cross-contamination throughout the kitchen and whether they adhered to other food safety behaviors throughout meal preparation.

The results of the observational study showed how easily bacteria can be spread when surfaces are not effectively cleaned and sanitized. The USDA recommends three easy ways to help prevent illness when preparing meat or poultry in your home.

1. Significantly decrease your risk by preparing foods that will not be cooked, such as vegetables and salads, BEFORE handling and preparing raw meat and poultry.

   In the observational study, 60 percent of the participants who washed their raw poultry had bacteria in their sink after washing or rinsing the poultry. Even more concerning is that 14 percent still had bacteria in their sinks even after they attempted to clean or sanitize the sink.

   If you wash your produce after washing meat or poultry, you risk splashing foodborne illness-causing germs onto your ready-to-eat foods. Researchers found that 26 percent of participants that washed raw poultry transferred bacteria from that raw poultry to their lettuce. If this were at home, they would have put that contaminated food directly into their mouths.

2. Thoroughly clean and then sanitize ANY surface that has potentially touched or been contaminated by raw meat and poultry or their juices, including the inner sink.

   Of the participants that did not wash raw poultry, 31 percent still managed to get bacteria from the raw poultry onto their lettuce. This high rate of cross-contamination was likely due to participants not effectively washing their hands during food preparation and from contaminating the sink or utensils when handling the raw poultry.

   To prevent this cross-contamination, clean sinks and countertops with hot soapy water and then apply a commercial or homemade sanitizer or disinfectant whenever they come in contact with any raw meat or poultry or their juices. Focus on the inner sink, any countertops surrounding the sink, knives and cutting boards and any place you set your meat or poultry or its packaging. Make sure commercial products are approved for food contact surfaces and follow the manufacturer’s instructions for use; some may require rinsing your surfaces after use. Wash hands immediately after handling raw meat and poultry. The Centers for Disease Control and Prevention (CDC) recommend you wet your hands with water, lather with soap and then scrub your hands for 20 seconds.

3. Destroy any illness-causing bacteria by cooking meat and poultry to a safe internal temperature as measured by a food thermometer.

Washing, rinsing or brining meat and poultry in saltwater, vinegar or lemon juice does not destroy germs. If you choose to remove skin, fat or blood from raw meat or poultry, you can do so on a clean cutting board, using a knife to cut away any flaws or patting the raw item with a paper towel and throwing it away when done. Immediately wash and then sanitize your cutting board and any knives or utensils and wash your hands thoroughly.

The only way to make sure your food is safe to eat is by cooking it to a safe internal temperature and checking it with a food thermometer.

More information about this study is available in an executive summary.

Washing Other Foods

Callers to the USDA Meat and Poultry Hotline may ask about washing other foods that are not regulated by the USDA. Our food safety experts recommend the following guidelines to safely handle eggs and produce in the home.

Washing Eggs

Do not wash eggs from the grocery store before putting them in the refrigerator. Washing is a routine part of commercial egg processing and the eggs do not need to be washed again. "Bloom," the natural coating on just-laid eggs that helps prevent bacteria from permeating the shell, is removed by the commercial washing process. It is replaced by a light coating of edible mineral oil, which restores protection for long-term home storage of eggs. Extra handling of the eggs in your home, such as washing them, could increase the risk of cross-contamination, especially if the shell becomes cracked.

Washing Produce

Before eating or preparing fresh fruits and vegetables, wash the produce under running tap water to remove any lingering dirt. This reduces any germs that may be present. If the fruits or vegetables have a firm surface, such as apples or potatoes, they can be scrubbed with a brush. Consumers should not wash fruits and vegetables with detergent, soap or commercial produce washes. These products are not approved or labeled by the U.S. Food and Drug Administration (FDA) for use on foods. You could ingest residues from soap or detergent absorbed on the produce and get sick.

Make sure your inner sink, countertops and utensils are cleaned and sanitized before you rinse your produce to avoid cross-contamination, especially from surfaces that have touched raw meat, poultry or seafood or their juices. When preparing fruits and vegetables, cut away any damaged or bruised areas because bacteria that can cause illness can thrive in those places. Immediately refrigerate any cut items such as salad or cut fruit for best quality and food safety.

Should I Wash Pre-Washed Produce?

At the store, you may find produce, like bagged salads or some cut and packaged fruits or vegetables, that is labeled as “pre-washed” or “ready-to-eat.” If you see this label, then you can safely use the produce without further washing. If you choose to wash produce marked as “pre-washed” or “ready-to-eat,” be sure that it does not come in contact with unclean surfaces or utensils, especially those that have touched raw meat, poultry or seafood or their juices. This will help to avoid cross-contamination.

Grocery Shopping

Many stores will have disinfecting wipes you can use to wipe down any carts or baskets you may touch during your shopping trip. This does not replace safe handling of food and food packaging while you’re in the store. Keep your raw meat, poultry and seafood products separate from any produce or ready-to-eat foods. You should use bags to keep these products separate. Wash your hands with soap and water for 20 seconds after going to the grocery store. Avoid touching your face, mouth or nose while grocery shopping.

If you use reusable bags while grocery shopping, be sure to wash them after each use with hot water and soap to prevent the spread of any germs. Clean and disinfect any surfaces and countertops where you put your groceries after handling and storing them.