The 11 most contaminated foods
According to the Centers for Disease Control and Prevention (CDC), every year one out of six Americans gets sick from foodborne illness, and of those people, 128,000 are hospitalized. Given the public concern about this issue, in 2009 the Center for Science in the Public Interest (CSPI) compiled a list of foods regulated by the U.S. Food and Drug Administration (FDA) that are most likely to infect people with foodborne diseases, such as salmonella, E. coli and listeria. Though two years have passed, experts still consider this “a pretty reliable list of the riskiest food items,” says Catherine Adams Hutt, PhD, RD, a food safety consultant based in Texas. Luckily, there are precautions you can take to decrease your odds of contamination. So from leafy greens to ice cream, read on to discover which 11 eats cause the most concern—and the specific measures you can take to protect yourself against sickness.
Although leafy greens, like spinach, romaine lettuce and arugula, pack a nutritional punch, they also rank at the top of the CSPI's list of riskiest foods. According to the organization's findings, leafy greens were responsible for 24% of all food-related outbreaks between 1990 and 2009. “These greens are grown on large fields, which are susceptible to E. coli contamination from grazing animals who are tracking manure, or from contaminated irrigation water," says Sarah Klein, food safety policy expert at the Center for Science in the Public Interest. Instead of buying pre-bagged lettuce—which includes leaves culled from thousands of different heads of lettuce, any of which could be contaminated—Klein recommends buying one head of lettuce or a three-pack of romaine hearts and prepping it yourself. "You're playing a little bit of a statistical game,” she says, noting that your chances of buying one contaminated head is less likely in comparison.
According to the CSPI, eggs were responsible for 11,163 foodborne illnesses between 1990 and 2009, mostly due to salmonella. The problem, according to Donald Schaffner, PhD, professor of microbiology at Rutgers University, is how easily eggs can become infected. "Eggs can be contaminated while still inside the chicken, if the hen is infected. They can also become infected in the hen house," he says. To protect yourself and (especially) any small children or elderly adults in your household, make sure to refrigerate eggs as soon as possible. Cheryl Luptowski, consumer affairs officer for NSF International, a public health and safety company, recommends adding eggs as well as dairy and meat items to your grocery cart last and heading directly home afterward. But this isn't the only way to reduce your risk when it comes to eggs; if you like them undercooked (over-easy, soft-boiled or poached) you may want to reconsider how you prepare them. According to the U.S. Department of Agriculture (USDA), eggs should be cooked until the yolk and white are firm; egg dishes should be cooked to an internal temperature of 160°. An even safer bet is to opt for pasteurized liquid eggs because the heat from the pasteurization process kills any bacteria and viruses. "They are easy to find, and often they're used in food service environments where they are feeding young children or the elderly," Dr. Adams Hutt says.
The risk surrounding tuna and high mercury levels has been widely touted in the media, but there's been less coverage about tuna and foodborne diseases. According to the CSPI's report, fresh tuna—linked with 269 outbreaks involving 2,341 reported cases of illness between 1990 and 2009—is the third most contaminated food. "Tuna can be contaminated with a toxin known as scombrotoxin, which can form if fish isn't [kept cool enough] after harvesting, during processing or shipping. Unfortunately, cooking tuna to a safe internal temperature doesn't eliminate the presence of this toxin once formed," Luptowski says. To decrease your risk, Luptowski recommends purchasing tuna from a reputable seafood supplier—whether that's a highly-regarded restaurant or local fish monger—and making sure to “keep raw tuna stored at a temperature of 40° or less until just before cooking."
According to the CSPI's list, between 1990 and 2009, oysters accounted for 132 outbreaks involving 3,409 cases of illness, mostly attributed to two sources: norovirus (which is generally spread by contaminated water or surfaces) and vibrio (a dangerous bacteria in the cholera family). Because of this, it’s crucial to follow certain precautionary measures—especially when eating oysters raw. "We tell people they should only be eating oysters that come out of the Pacific Northwest or New England; colder waters where bacteria can't survive," Klein says. "Don't purchase or eat oysters from the Gulf Coast region or oysters that are coming out of warmer waters." When served or sold raw, oysters should be marked with the region of origin. If it’s unclear or not indicated, ask your waiter or store’s fish monger. In general, Dr. Schaffner urges people to cook all seafood before consuming—which means nixing raw oysters, when possible.
Potatoes were responsible for 108 outbreaks involving 3,659 reported cases of illness between 1990 and 2009—most commonly salmonella and E. coli. The problem, say experts, isn't the potatoes themselves, but the dishes they are used in. Luptowski explains that the most common culprit is potato salad, which people often don't store properly. "It needs to be transported in a cooler with ice packs or kept in the refrigerator until just before serving. And if you're going to serve it at a buffet, serve it on ice." She also recommends using store-bought mayonnaise instead of homemade if you're going to transport and serve it. "It's less likely to get bacteria," she says. A similar problem occurs with mashed potatoes and baked potatoes. "If they are allowed to sit around warm, they can grow foodborne illnesses," says Bob Gravani, PhD, professor of food science at Cornell University. "You need to cool them down, eat them quickly or keep them at a hot enough temperature."
Cheese accounted for 83 outbreaks involving 2,761 reported cases of foodborne illness from 1990 to 2009. However, you can greatly reduce your risk of sickness by simply avoiding unpasteurized and raw milk cheeses (usually bought in specialty shops). "Many cases of foodborne illness are due to the consumption of unpasteurized cheese. Families should look [on the label] for cheese that has been pasteurized," Luptowski says. "Once purchased, most cheeses should be stored in the refrigerator either in the original bag or in an air-tight food storage container. Soft cheeses [feta, Brie, Camembert, etc.] and shredded cheeses should not be left out or stored at room temperature for more than two hours; discard if left out past two hours." There's an additional concern regarding soft cheeses, which can become contaminated with listera, a type of bacteria, after the pasteurization process. Since these types of cheeses are not usually cooked prior to serving, the CDC recommends pregnant women avoid consuming them, since infection can be harmful to the fetus and lead to serious complications.
It's mostly homemade ice cream that's to blame for foodborne illness. "More than half the time, ice cream that causes outbreaks is linked to private homes, so it's most likely people making their own ice cream with raw eggs and/or raw milk," Klein says. According to the CSPI, from 1990 to 2009, ice cream accounted for 74 outbreaks involving 2,594 illnesses between 1990 and 2009. To protect yourself, Klein recommends making ice cream with pasteurized eggs, which you can get in the shell or in liquid form. However, women who are expecting should also avoid both homemade and soft-serve ice cream. "Pregnant women should be wary of soft-serve ice cream because listeria is a hardy bug that can live on metal and thus thrives inside soft ice cream machines, which are impossible to clean effectively," Klein says.
Unlike other raw produce, which is usually exposed to contaminants during the handling process, tomatoes can be contaminated at just about any point from the field to manufacturer, which makes them particularly risky. In fact, tomatoes are most often contaminated as they grow, when salmonella enters a tomato plant through its roots, flower or small cracks in the skin or stem. According to the CSPI's list, tomatoes accounted for 31 outbreaks involving 3,292 reported cases of illness from 1990 to 2009. "Tomatoes can be contaminated in the field or by cross-contamination during harvest, washing, transport or in the home," says Dr. Schaffner. "Even cut tomatoes support the growth of salmonella and other pathogens." To reduce your risk of exposure, Dr. Schaffner suggests always washing tomatoes before use, and slicing them on a disinfected cutting board—not one that’s used to for meat or dairy. Any leftover sliced tomatoes should be promptly refrigerated.
Raw sprouts are a nutritious addition to salads and sandwiches, but after the FDA reported 31 outbreaks involving 2,022 cases of illness from 1990 to 2009 involving both salmonella and E. coli, they became a particular concern to food safety experts. "We are currently advising consumers to avoid raw sprouts. For now, the sprout industry has been unable to find a way to produce sprouts safely because of the way they are grown," Klein says. The problem, according to Dr. Schaffner, is that contamination goes all the way down to the seed. "Sprout seeds can contain pathogens, and if they do, those pathogens multiply during the sprouting process," he says. If you do choose to consume them raw, Dr. Adams Hutt suggests looking for signs that they have been improperly handled, such as wilted or soggy sprouts. "There are regulations and good practices the processors follow, but you've also got to pay attention and look for signs of spoilage," she says. "And make sure you wash them and keep them cool once you get home."