Food safety involves protecting food from all contamination, including pathogenic organisms, chemicals, toxins, and physical contaminants, at all stages of the food-production chain. This includes farming through harvesting or slaughtering, processing, packaging, distribution, retail sales, and food preparation. An organic or vegetarian diet, does not protect a person from food contamination. Fruits and vegetables can be contaminated in the fields from animal feces or pesticides, as well as during harvesting, processing, distribution, and storage.
The food supply in the United States is probably the safest in the world, and serious breaches of food safety are relatively rare. Nevertheless, the United States Centers for Disease Control and Prevention (CDC) reported in 2011 that about 48 million Americans—one in six—suffered from foodborne illness (food poisoning) every year. The CDC estimates that about 97% of all food poisoning comes from improper food handling. Of that, 80% occurs from food prepared in businesses (e.g., restaurants or work cafeterias) or institutions (e.g., schools or jails). The remaining 20% occurs from food prepared at home.
Internationally, food contamination and large-scale food recalls appear to be on the rise. The 2011 Fukushima Daiichi nuclear power plant disaster in Japan raised fears about radiation-contaminated food. Bioterrorism experts worry that disease-causing organisms or toxic chemicals could be intentionally introduced into food or water supplies causing mass contamination. Scientists worry that climate change may increase the risk of contamination from pesticides and other chemicals, biotoxins, and pathogenic microbes. Various groups question the safety of food derived from genetically modified organisms (GMOs).
Although food safety includes preventing the contamination of crops with unsafe levels of pesticides and herbicides and avoiding poisonous mushrooms, mercury-contaminated fish, and shellfish contaminated with algal toxins, most illnesses resulting from food contamination are caused by pathogenic organisms—bacteria, viruses, and parasites. Although foodborne illnesses can be very unpleasant, they are usually mild and short-lived. However, they can cause serious complications and even death, particularly among the very young, the very old, pregnant women and their unborn children, and people with weakened or compromised immune systems. Foods that are tainted with natural toxins, synthetic chemicals, or physical contaminants can also cause serious or fatal illnesses.
In the United States, the vast majority of food poisonings of known origin are caused by one of eight pathogens:
Contaminants that jeopardize food safety change over time, requiring constant surveillance. Improved food safety techniques, including milk pasteurization, safer canning methods, and water treatment, have helped overcome diseases, such as typhoid fever, tuberculosis, and cholera in the developed world. However, other foodborne diseases, such as listeriosis, appear to be on the rise. In 2011, at least 29 people died and at least 139 people across 28 states were sickened from eating cantaloupe contaminated with L. monocytogenes, which was traced to unsanitary conditions and poor handling at a single farm. There have been major recalls of ground beef, lettuce, and spinach contaminated with STEC. Strain O157:H7 is the most commonly identified STEC in the United States. There have also been nationwide recalls of peanut butter contaminated with salmonella.
Media reports of contaminated foods, frequent product recalls, and U.S. government initiatives have raised public awareness of food-safety issues. However, globalization of the food supply, industrial farming, concentrated animal feeding operations (CAFOs), and centralized slaughterhouses and processing facilities that pool ingredients from hundreds or thousands of plants and animals have made monitoring food safety very difficult.
The FDA can request the recall of about 80% of foods consumed domestically, as well as contaminated animal feed. Food additives and substances that contact food, such as packaging, must be approved by the FDA as safe. However, other food ingredients, including some that have been used for many years, do not require FDA approval. The FDA also regulates food irradiation that helps protect against disease-causing bacteria and delays spoilage. Irradiated foods include spices, red meat, poultry, some shellfish, and fresh iceberg lettuce and spinach.
Despite government regulation, almost all food safety testing is performed by the food companies themselves. This means that the responsibility of ensuring food is safe to eat falls upon food manufacturers and producers, as well as consumers. Cleanliness, food separation, and proper cooling and cooking are key to food safety.
Frequent hand washing before, during, and after preparing and eating food is a central tenet of food safety. Hand washing is especially important after handling raw meat, poultry, eggs, and seafood. Hands should be rubbed together with soap under warm, running water for at least 20 seconds (two choruses of “Happy Birthday”). Soap should be rubbed between fingers, down to the wrists, and into fingernails. Paper towels should be used for drying, since cloths spread microbes.
Fresh fruits and vegetables should be washed under running water and scrubbed with a clean brush or with both hands just before cooking or eating. They should be washed both before and after peeling to prevent salmonellosis. Outside leaves of lettuce and cabbage should be discarded. Produce that is not eaten immediately should be dried with a clean cloth or disposable towel, since surface moisture can promote microbial growth. Raw meat and poultry should not be washed, because washing increases the danger of cross-contaminating surfaces.
Cutting boards, utensils, dishes, appliances, kitchen bins, and countertops should be carefully cleaned regularly with hot, soapy water. Dishtowels should be washed in hot water. Sponges should be disinfected in a chlorine bleach solution and replaced frequently. Two minutes in the microwave will kill harmful bacteria in wet sponges. Smelly sponges, cloths, utensils, or surfaces suggest microbial growth and require proper cleaning or disposal.
Juices from raw meat, poultry, seafood, and eggs should never come in contact with uncooked, ready-to-eat foods, such as fruits and vegetables. Such foods should remain separated in the grocery cart, in bags, and in the refrigerator with their juices contained.
Cutting boards are a common source of cross-contamination. One cutting board should be set aside for raw meat, poultry, and seafood, and another for cutting vegetables, breads, and other ready-to-eat foods. Boards can be appropriately labeled or colored (e.g., green for vegetables). The meat board should be washed thoroughly with hot, soapy water or in a dishwasher immediately after use. Old cutting boards, especially wooden boards with cracks, crevices, and knife scars, should be discarded. Cross-contamination of cooked foods can occur when plates or surfaces that held raw meat, poultry, or seafood are reused for cooked food.
Cold temperatures slow or halt bacterial growth. Although refrigerating leftovers might seem obvious, among the most common calls fielded by the USDA Meat and Poultry Hotline are from college students asking whether it is safe to eat pizza that sat out overnight (it is not). Refrigerators should be kept at 40°F (4°C) or below and freezers at 0°F (-18°C). A refrigerator thermometer can ensure the correct temperature. Raw meat, poultry, eggs, seafood, cut fruits and vegetables, and leftovers should not be left at room temperature for more than two hours or one hour at temperatures above 90°F (32°C). Refrigerators should be cleaned out often, since too much food can prevent cold air from circulating properly.
Foods are generally labeled with refrigeration/freezing instructions and expiration dates. Most foods are safe in the refrigerator for at least three to four days. Exceptions include stuffing, some cooked patties, gravies, and broths, which should only be kept for one to two days. Raw meats should be marinated in the refrigerator rather than at room temperature. Frozen foods should be defrosted in the refrigerator. Food defrosted in warm water or a microwave should be cooked immediately.
Uncooked or undercooked meat, poultry, eggs, and egg products are potentially unsafe. Only a good meat thermometer—not the color of the meat or its juices—can determine whether meat is adequately cooked. The thermometer should be placed in the thickest portion of meat or poultry pieces, away from bone, fat, and gristle, and at the center of casseroles and egg dishes. Appropriate minimum temperatures include:
The most important food safety rule may be “when in doubt, throw it out.” Although spoiled foods often have an unpleasant taste or smell, some people, especially the elderly, may have difficulty telling whether food has gone bad by smell alone. Further, bacterial growth does not necessarily result in a bad taste or smell or discoloration. Dating foods when first refrigerated can help prevent the consumption of outdated items.
Consumers should be aware of updated food safety information and food recalls. Reports of suspect food should be made to the store where the food was purchased, to the manufacturer, or to the FDA or FSIS, depending on the type of food. Any identifying information on the packaging should be noted.
Ignorance of or disregard for food safety can lead to foodborne illness. Outbreaks of foodborne illness are common in restaurants, cafeterias, nursing homes, prisons, and family and community gatherings where large numbers of people are fed “from the same pot.” Contaminated food usually causes diarrhea and often causes nausea, vomiting, abdominal cramps, and fever, which can pose significant health risks for infants, the elderly, and those with special medical conditions. Even moderate diarrhea and vomiting poses a risk for dehydration, especially in infants and young children. Although symptoms of food poisoning often occur soon after eating contaminated food, symptoms may not be apparent for up to a week.
Pregnant women and their unborn babies, infants, and young children are particularly vulnerable to the effects of contaminated food. Thus, awareness of food safety, good food-hygiene practices, and possibly the avoidance of “high-risk” foods are especially important for pregnant women, parents, and caregivers. Vigilant food safety is particularly important when young children attend summer picnics, cookouts, and outdoor buffets.
Breast-feeding is the best food-safety practice for babies. Breast milk and infant formula must be carefully stored. Mixed formula should be kept in the refrigerator for no more than 24 hours. Expired formula and any formula or breast milk left in the bottle after feeding should be discarded. Bottles can become contaminated with salmonella within two hours at room temperature. Infants under one year should never be given food containing honey, even if it is cooked, since honey can contain spores of Clostridium botulinum, the bacterium that produces the deadly paralytic toxin that causes botulism. Although the toxin is destroyed by boiling, the spores are not.
Baby food containers should always be checked to ensure that they have been well sealed and that the food has not reached its expiration date. Leftover food that has been contaminated with the spoon used to feed a baby should be discarded or moved to a dish that the same child will not eat from again.
See also Bioterrorism ; Biotoxins ; Centers for Disease Control and Prevention ; Climate change ; Environmental Protection Agency (EPA) ; Food additives ; Food contamination ; Food poisoning ; Foodborne illness ; Listeriosis .
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Margaret Alic, PhD
Revised by Tish Davidson, AM