Food workers prevent biological contamination through a combination of proper handwashing, temperature control, separation of raw and ready-to-eat foods, and consistent sanitation of surfaces and equipment. Biological hazards, which include bacteria, viruses, and parasites, are the leading cause of acute foodborne illness. In the U.S. alone, contaminated food causes an estimated 645,000 to 1.68 million illnesses and 378 deaths each year. Every step in food handling, from receiving ingredients to serving a plate, presents an opportunity for these pathogens to spread or multiply.
Biological Hazards in Food
The pathogens food workers need to guard against fall into three categories: bacteria, viruses, and parasites. Common bacterial threats include Salmonella, E. coli, Campylobacter, Staphylococcus aureus, and Clostridium perfringens. On the viral side, norovirus actually causes more foodborne outbreaks than any other single pathogen, though the true number is hard to pin down because norovirus also spreads through non-food routes. Hepatitis A is another serious viral concern. Parasites are less common in developed food systems but still a risk, with more than 70 species capable of infecting humans through contaminated food or water.
These organisms can enter food at any point: from contaminated raw ingredients, from a sick food worker’s hands, from improperly cleaned equipment, or simply from food sitting at unsafe temperatures long enough for bacteria to multiply. The goal of every prevention practice below is to either kill these organisms, stop them from reaching food in the first place, or deny them the conditions they need to grow.
Handwashing: The Single Most Effective Step
Proper handwashing is the most effective way to prevent the spread of germs in a food setting. The CDC outlines five steps: wet your hands under clean running water (warm or cold), apply soap, lather thoroughly including the backs of your hands, between your fingers, and under your nails, scrub for at least 20 seconds, then rinse and dry with a clean towel or air dryer.
Food workers should wash their hands before starting work, after touching raw meat or poultry, after using the restroom, after sneezing or coughing, after handling garbage, and after any interruption in their task. The 20-second scrubbing time is the minimum, not a suggestion. A quick rinse under the faucet does almost nothing to remove the bacteria and viruses that cause foodborne illness.
Avoiding Bare-Hand Contact With Ready-to-Eat Food
The FDA Food Code prohibits food workers from touching exposed ready-to-eat food with bare hands. Ready-to-eat food is anything that will be served without further cooking: salads, bread, sliced fruit, deli meats, and plated dishes. Instead, workers must use utensils like tongs, spatulas, deli tissue, or single-use gloves.
When gloves are used, they are meant for one task only. A worker who handles raw chicken and then needs to assemble a sandwich must discard the first pair and put on fresh gloves. Gloves should also be changed whenever they become damaged or soiled, or whenever the worker is interrupted and steps away from the task. Gloves are not a substitute for handwashing. Hands should be washed before putting on a new pair.
Keeping Raw and Ready-to-Eat Foods Separate
Cross-contamination happens when juices or particles from raw meat, poultry, seafood, or eggs come into contact with foods that won’t be cooked again. This is one of the most common ways biological hazards reach the plate.
Food workers should use separate cutting boards and prep surfaces for raw proteins and for produce or other ready-to-eat items. During storage, raw meat, poultry, and seafood belong in sealed containers or tightly wrapped packaging on the lowest shelves of the refrigerator, so their juices can’t drip onto anything below. Ready-to-eat items go on higher shelves. The same principle applies during receiving and transport: raw proteins should never share bags, bins, or surfaces with foods that are eaten without cooking.
Temperature Control: The Danger Zone
Bacteria multiply fastest between 40°F and 140°F, a range known as the danger zone. Within this window, bacterial populations can double in as little as 20 minutes. That means a piece of chicken left on a counter at room temperature can go from safe to potentially dangerous in a surprisingly short time.
The core rule is simple: never leave perishable food in the danger zone for more than two hours. If the ambient temperature is above 90°F (common in outdoor events or hot kitchens near grills), that window shrinks to one hour. Cold foods should be held at 40°F or below, and hot foods at 140°F or above. Using thermometers regularly, rather than guessing, is the only reliable way to verify temperatures during cooking, holding, cooling, and reheating.
Cooking to Safe Internal Temperatures
Cooking kills biological hazards, but only if the food reaches the right internal temperature throughout. Different proteins have different thresholds because different pathogens require different levels of heat to destroy:
- Poultry (whole birds, breasts, wings, thighs, ground poultry, and stuffing): 165°F
- Ground beef, pork, veal, and lamb: 160°F
- Eggs and egg dishes: 160°F
- Beef, pork, veal, and lamb steaks, chops, and roasts: 145°F, with a three-minute rest before cutting or serving
- Fish and shellfish: 145°F
- Leftovers and casseroles: 165°F when reheated
The rest time for steaks and roasts matters because the internal temperature continues to rise slightly after the meat comes off the heat, finishing off remaining pathogens. A food thermometer inserted into the thickest part of the food is the only accurate way to check. Color and texture are unreliable indicators.
Cleaning and Sanitizing Surfaces
Cleaning and sanitizing are two distinct steps, and both are necessary. Cleaning uses soap or detergent to physically remove dirt, grease, and organic matter from a surface. Sanitizing uses a chemical solution to kill bacteria that remain after cleaning. Skipping the cleaning step makes sanitizing less effective because organic residue can shield bacteria from the sanitizer.
Food contact surfaces (cutting boards, prep tables, slicers, utensils) should be cleaned and sanitized after each use, especially when switching between raw proteins and other foods. When using a sanitizing product, the key detail is contact time: the surface must stay wet with the solution for the full duration listed on the product label, or the sanitizer won’t work as intended. Wiping it off too soon reduces its effectiveness significantly.
Managing Sick Workers
A food worker who is vomiting, has diarrhea, or has been diagnosed with an illness caused by norovirus, Salmonella, hepatitis A, or other transmissible pathogens should not be handling food. These organisms spread easily from person to person through contaminated hands, and even small amounts of viral particles (particularly norovirus) can cause infection. Food workers with symptoms of gastrointestinal illness should report their condition to a manager and be excluded from food preparation duties until they are no longer symptomatic or have been cleared to return, depending on the pathogen involved.
Open wounds, cuts, or sores on the hands or arms also pose a risk, particularly for Staphylococcus aureus, which commonly lives on human skin. These should be completely covered with a waterproof bandage and a glove before the worker handles food.
Proper Cooling and Reheating
Cooling cooked food is a surprisingly risky step because it can spend a long time passing through the danger zone. Large batches of soup, rice, or cooked meat should be divided into shallow containers to cool faster, rather than being placed in the refrigerator as one large pot. Ice baths and stirring also speed the process.
When reheating leftovers or previously cooked food for service, the food must reach 165°F throughout. Slow, gentle reheating that only warms food to a lukewarm temperature creates ideal conditions for bacteria that survived initial cooling to multiply rapidly. Reheating should be done quickly, and the temperature verified with a thermometer before serving.