Chapter 1 – Kitchen and Food Safety
1.3 Safety of Our Foods
What Is a Safe Food Supply?
| Who Helps Keep Food Safe? | Primary Responsibility |
|---|---|
| Food and Drug Administration (FDA) | Oversees the safety of most foods, including seafood, produce, dairy products, and packaged foods. |
| United States Department of Agriculture (USDA) | Inspects meat, poultry, and processed egg products to help ensure they are safe and properly labeled. |
| Centers for Disease Control and Prevention (CDC) | Tracks foodborne illnesses, investigates outbreaks, and helps prevent the spread of foodborne disease. |
| State and Local Health Departments | Inspect restaurants, grocery stores, schools, and other food service establishments to enforce food safety regulations. |
| Food Industry | Farmers, manufacturers, distributors, grocery stores, and restaurants follow food safety standards to reduce contamination. |
| Consumers | Store, prepare, cook, and handle food safely at home to help prevent foodborne illness. |
In the United States, agencies such as the USDA, FDA, CDC, and state and local health departments help monitor food production, investigate outbreaks, enforce food safety regulations, and educate consumers about safe food-handling practices.
Food safety inspections occur throughout the food system—from farms and food processing plants to grocery stores, restaurants, and school cafeterias. If you have ever noticed a restaurant health inspection score posted near the entrance, you have seen one example of how these safeguards are monitored at the local level.
Farmers, food manufacturers, distributors, retailers, and restaurants also help keep food safe by following established food safety standards. Consumers play an equally important role by storing, preparing, cooking, and handling food safely at home.
Despite these safeguards, foodborne illnesses still occur. The World Health Organization estimates that about 1 in 9 people worldwide—approximately 833 million individuals—become ill from contaminated food each year.[1] This highlights an important point: food safety depends on everyone working together—from farm to table.
Before reading further, watch the short FAO video that describes how food safety is a shared responsibility.
VIDEO: “Food Safety Is Everyone’s Responsibility,” by The Food and Agriculture Organization of the United Nations. June 2021, (1 minute)
Although some foods become contaminated during processing, many foodborne illnesses result from improper food handling by consumers. Disease-causing microbes, or pathogens, can contaminate food and cause symptoms such as nausea, vomiting, stomach cramps, and diarrhea. Symptoms may range from mild discomfort to severe illness and, in rare cases, can be life-threatening.
What are Food Contaminants?
Food contamination can be obvious, such as finding a piece of plastic in a sandwich, or invisible, such as harmful bacteria in food that looks and smells normal. Food contaminants are typically grouped into three categories as outlined in the table below.
| Type of Contaminant | Examples | Potential Risks |
|---|---|---|
| Physical | Glass, jewelry, plastic, bones, and insects | Choking, cuts, broken teeth |
| Chemical | Pesticides, cleaning agents, and excessive food additives | Illness or long-term health effects |
| Biological | Bacteria, viruses, molds, and parasites | Foodborne illness |
Biological contaminants are the most common cause of foodborne illness. These contaminants are living organisms, or microorganisms, such as bacteria, viruses, parasites, and molds that can contaminate food and cause disease. Symptoms may include nausea, vomiting, diarrhea, stomach cramps, and fever.
One of the most common biological contaminants is Salmonella, a bacterium that causes an estimated 1.35 million infections, 26,500 hospitalizations, and 420 deaths in the United States each year. It can contaminate many foods but is most often associated with raw or undercooked poultry, eggs, meat, unpasteurized milk, and fresh produce.[2]
To understand how foodborne illness occurs, it is helpful to understand the conditions that allow microorganisms to grow.
How Microorganisms Grow
Many foodborne illnesses are caused by microorganisms that multiply under certain conditions that promote their growth. Food safety professionals use the acronym FAT TOM to describe these six conditions as described below.
| Condition | Why It Matters |
|---|---|
| Food | Provides nutrients for growth |
| Acidity | Most harmful bacteria prefer low-acid foods |
| Temperature | Bacteria grow rapidly in the Temperature Danger Zone |
| Time | More time allows more growth |
| Oxygen | Some microbes require oxygen |
| Moisture | Water is essential for growth |
Consumers have the greatest control over time and temperature, making proper cooking, cooling, and refrigeration essential for food safety.
Potentially Hazardous Foods
. Potentially hazardous foods (PHFs) are foods that allow harmful bacteria to grow quickly if they are not kept at safe temperatures. Examples include meat, poultry, seafood, dairy products, cooked rice, and cut fruits and vegetables. Because these foods can quickly become unsafe, they require refrigeration or other temperature-control measures.
The Temperature Danger Zone
Have you ever left a pizza on the counter overnight and wondered, “Is it still safe to eat?” The answer depends on how long it has been sitting in the Temperature Danger Zone.
The Temperature Danger Zone is the range between 40°F and 140°F (4°C to 60°C) where bacteria grow most rapidly. Under the right conditions, some bacteria can double in number in as little as 20 minutes. Even if food looks and smells normal, it may contain enough harmful bacteria to make you sick.
To reduce the risk of foodborne illness:
- Keep cold foods at 40°F (4°C) or below.
- Keep hot foods at 140°F (60°C) or above.
- Refrigerate perishable foods and leftovers within 2 hours (or within 1 hour if the temperature is above 90°F [32°C]).
Note: The FDA Food Code, which is used by restaurants and other food service operations, defines the temperature danger zone slightly differently. It recommends keeping cold foods at 41°F (5°C) or below and hot foods at 135°F (57°C) or above. Although these limits differ slightly from the USDA guidelines commonly used for home food safety, the goal is the same: keep food out of the temperature range where harmful bacteria can multiply quickly.
WHAT ARE THE TYPES OF FOODBORNE ILLNESSES?
Many people assume the last food they ate caused their illness. In reality, symptoms of foodborne illness may not appear for hours—or even days—after eating contaminated food, making it difficult to identify the source.
Foodborne illness is a general term for illnesses caused by consuming food contaminated with harmful bacteria, viruses, parasites, or toxins. There are two main types: foodborne infections and foodborne intoxications. As shown in Table 1.6, infections occur when disease-causing microorganisms are eaten and multiply in the body, whereas intoxications result from consuming toxins that are already present in food. Although hundreds of foodborne illnesses have been identified, most cases are caused by a relatively small number of pathogens, including Salmonella, Escherichia coli (E. coli), Campylobacter, Listeria, and norovirus.[3]
Table 1.4 distinguishes between these two types of foodborne illness.
| Type | What Happens? | Examples |
|---|---|---|
| Foodborne Infection | Harmful bacteria, viruses, or parasites are eaten and multiply in the digestive tract | Salmonella, E. coli, Campylobacter, norovirus |
| Foodborne Intoxication | Toxins already present in food are consumed. The toxin—not the microorganism—causes the illness. Some toxins remain even after cooking. | Toxins produced by Staphylococcus aureus or Clostridium botulinum |
Most foodborne illnesses are preventable. The next section describes the four basic food safety steps—Clean, Separate, Cook, and Chill—that can greatly reduce your risk of becoming sick from contaminated food.
CLASS DISCUSSION QUESTIONS
- Food safety is often described as a “farm-to-table” responsibility.
Who do you think has the greatest responsibility for keeping food safe—government agencies, the food industry, restaurants, or consumers? Explain your reasoning. - Think about the last time you left food sitting out on a counter, in a car, or at a party.
Was that food in the Temperature Danger Zone? What factors influence people’s decisions about whether food is still safe to eat? - Many people assume they can tell whether food is safe by looking at it, smelling it, or tasting it.
Why can this be a risky assumption? What are some better ways to determine whether food is safe to eat?
Review Questions
Check your understanding of this section by answering these questions.
attributions
This chapter is an adaptation of “Chapter 17. Food Safety” in Human Nutrition:2020 Edition by University of Hawai‘i at Mānoa Food Science and Human Nutrition Program licensed under a Creative Commons Attribution 4.0 International License.
- World Health Organization. Estimating the burden of foodborne diseases. World Health Organization. Accessed June 25, 2026. https://www.who.int/activities/estimating-the-burden-of-foodborne-diseases ↵
- Centers for Disease Control and Prevention. About Salmonella Infection. Updated October 4, 2024. Accessed June 25, 2026. https://www.cdc.gov/salmonella/about/index.html ↵
- Scallan Walter EJ, Cui Z, Tierney R, et al. Foodborne illness acquired in the United States—major pathogens, 2019. Emerg Infect Dis. 2025;31(4). doi:10.3201/eid3104.240913 ↵
United States Department of Agriculture
Food and Drug Administration
Centers for Disease Control and Prevention
When two or more people get the same illness from the same contaminated food or drink.
Food production, processing, distribution, consumption and
disposal of foods. Also known as food chain.
An illness that results after eating a contaminated food. Also called foodborne diesease or food poisoning.
A variety of operations by which raw foodstuffs are made suitable for consumption, cooking, or storage.
Microorganisms which include bacteria, viruses, and fungi.
Disease-causing microorganisms
Stomach queasiness, the urge to vomit
To eject matter from the stomach through the mouth
Loose, watery feces that occur more frequently than usual
A microscopic living organism, such as a bacterium, mold, yeast, or parasite. Some microorganisms are helpful, while others can cause disease. AKA microbe.
