Foodborne illnesses continue to pose serious public health risks across the globe, and in the United States alone, the Centers for Disease Control and Prevention (CDC) estimates that one in six Americans—roughly 48 million people—get sick each year from contaminated food. Among the most notorious culprits behind these illnesses are Salmonella, Escherichia coli (E. coli), and Listeria monocytogenes. These bacteria are resilient, hard to detect in the early stages of contamination, and capable of causing severe or even fatal outcomes in vulnerable populations. While food safety protocols have improved drastically over the past decades, certain types of food still pose a disproportionately high risk of harboring these pathogens. Five such food groups stand out for their recurring involvement in outbreaks and recalls: leafy greens, deli meats, unpasteurized dairy, raw sprouts, and undercooked ground beef.
This article provides a deep dive into the five most dangerous food products most often linked with Salmonella, E. coli, and Listeria outbreaks: leafy greens, deli meats, raw milk and soft cheeses, sprouts, and ground beef. Each of these categories has a well-documented history of contamination, outbreaks, and deaths, and they present unique risks due to how they are processed, handled, or consumed.
1. Leafy Greens (Spinach, Romaine, Lettuce, Kale)
Fresh leafy greens are among the most dangerous foods when it comes to bacterial contamination, particularly with E. coli and Salmonella. Despite being a dietary staple praised for its nutritional value, leafy greens have been linked to repeated and sometimes fatal outbreaks across the United States.
The Centers for Disease Control and Prevention (CDC) reports that more than half of all multistate E. coli O157:H7 outbreaks in the U.S. between 2009 and 2020 were linked to leafy greens. Romaine lettuce, in particular, was implicated in several nationwide recalls.
Contamination often occurs at the farm level. Leafy greens are typically grown in open fields near cattle operations, where water runoff from livestock can contaminate irrigation sources with pathogenic bacteria. Furthermore, these vegetables are usually eaten raw, meaning that any bacteria present on the leaves are consumed directly without a kill step like cooking.
Once harvested, leafy greens are washed and bagged in large batches. If one contaminated leaf enters the processing plant, it can contaminate thousands of bags due to shared wash water and equipment. This amplification risk makes prewashed, bagged salads particularly dangerous.
Adding to the problem is the limited shelf life of leafy greens. By the time contamination is detected through illness reports and product testing, the tainted products are often already consumed or spoiled, making traceability and prevention difficult.
2. Deli Meats (Cold Cuts, Ready-to-Eat Processed Meats)
Deli meats and cold cuts are a prime vehicle for Listeria monocytogenes, a bacterium that thrives in cold, moist environments such as refrigerated storage facilities and meat-processing plants. Unlike many other foodborne pathogens, Listeria can multiply at refrigerator temperatures, making it uniquely suited to contaminate processed meats over time.
This risk is especially high in sliced, ready-to-eat deli meats. Slicing machines are often shared between different meat products and may be cleaned infrequently or inadequately. If Listeria establishes a foothold in a slicer or production line, it can persist for months, silently contaminating thousands of packages of meat before being detected.
Listeria is particularly dangerous for pregnant women, the elderly, and immunocompromised individuals. It causes listeriosis, a disease that can lead to miscarriage, stillbirth, sepsis, or meningitis. The CDC estimates that although Listeria causes fewer illnesses than other pathogens, it is one of the deadliest foodborne bacteria, with a hospitalization rate above 90% and a fatality rate approaching 25%.
3. Raw Milk and Soft Cheeses (Queso Fresco, Brie, Feta)
Soft cheeses such as queso fresco, brie, camembert, blue-veined cheeses, and feta are especially problematic because of their high moisture content and relatively low acidity. These conditions are ideal for Listeria to survive and proliferate. Unlike hard cheeses, which are more resistant to microbial growth, soft cheeses allow Listeria to multiply over time in the refrigerator.
In several of the most serious Listeria outbreaks, illnesses have been linked to queso fresco, raw milk cheese, and deli meats – each resulted in deaths or fetal losses.
Raw milk also frequently tests positive for Salmonella, Campylobacter, and E. coli. Because raw milk bypasses the kill step that eliminates pathogens, any contamination introduced at the farm level—from cow udders, fecal matter, or milking equipment—can be directly passed to the consumer. According to the CDC, people who drink raw milk are 150 times more likely to get sick than those who drink pasteurized milk!
4. Sprouts (Alfalfa, Mung Bean, Clover, Radish)
Sprouts have a reputation as a health food, but they are one of the riskiest foods in any supermarket. This is because the conditions required to grow sprouts—warmth, humidity, and moisture—are the same conditions that allow bacteria like Salmonella and E. coli to thrive.
Sprouts are typically grown from seeds in moist environments, and if those seeds are contaminated with bacteria, there is no step in the sprouting process that will kill the pathogens. Washing the sprouts does little to reduce risk because bacteria can grow inside the sprout itself or stick tightly to its surface.
Between 1996 and 2020, the FDA documented more than 50 outbreaks of foodborne illness linked to raw and lightly cooked sprouts, resulting in thousands of illnesses and dozens of hospitalizations. In fact, in the United States, alfalfa and clover sprouts are the most commonly implicated. Many grocery chains have stopped selling raw sprouts altogether due to the risk, but they remain available in farmers’ markets and restaurants. Cooking sprouts can reduce the danger, but they are almost always eaten raw, increasing the likelihood of infection.
5. Ground Beef
Ground beef is a high-risk food for both E. coli and Salmonella. The grinding process itself is the central problem: when beef is ground, bacteria present on the surface of the meat can be mixed throughout the product. That means the interior of a burger may be contaminated even if the outside looks fully cooked.
E. coli O157:H7 is the most notorious strain linked to undercooked ground beef. This strain produces a Shiga toxin that can lead to severe complications, including kidney failure. The 1993 Jack in the Box outbreak, which killed four children and sickened hundreds, brought national attention to the dangers of undercooked burgers. It also catalyzed significant regulatory changes, including mandatory pathogen testing by the USDA’s Food Safety and Inspection Service (FSIS).
Despite improvements in testing and oversight, outbreaks still occur. In the last ten years or so, there have been a number of outbreaks, including a multistate outbreak of E. coli O26 linked to ground beef sickened more than 200 people and led to numerous recalls. Another involved Salmonella Dublin, a strain more commonly associated with cattle, which infected dozens of people and led to multiple hospitalizations.
Ground beef is also difficult to handle safely in home kitchens. Consumers often undercook burgers, fail to use meat thermometers, or allow cross-contamination between raw meat and other surfaces or foods. Additionally, large batches of ground beef produced at centralized meatpacking facilities can distribute contaminated product across the country before a problem is detected.
The Five Dangerous Foods: Its Hard to Live Without These!
Although foodborne pathogens can contaminate virtually any product, certain foods are statistically and epidemiologically more dangerous. Leafy greens, deli meats, raw milk and soft cheeses, sprouts, and ground beef are the leading culprits when it comes to recurring and severe outbreaks of Salmonella, E. coli, and Listeria. These products pose unique risks due to their production, storage, and consumption characteristics.
Public health agencies such as the CDC, FDA, and USDA have implemented measures to detect and prevent contamination, including Whole Genome Sequencing (WGS) of bacterial strains, improved traceback investigations, and better industry oversight. Still, consumers play a crucial role in minimizing risk. Understanding which foods carry the highest potential for infection—and why—is essential in reducing exposure and staying safe.
By recognizing the risks associated with these five food categories, consumers can make more informed decisions, demand higher safety standards, and adopt safer food-handling practices in their own kitchens. Ultimately, food safety is a shared responsibility—from farm to fork.
