NEW YORK (CNNMoney.com) -- Leafy greens -- including lettuce and spinach -- top the list of the 10 riskiest foods, according to a study from a nutrition advocacy group released Tuesday.
The Center for Science in the Public Interest listed the following foods, in descending order, as the most risky in terms of illness: leafy greens, eggs, tuna, oysters, potatoes, cheese, ice cream, tomatoes, sprouts and berries.
The scientists rated these foods, all of them regulated by the Food and Drug Administration, by the number of illnesses associated with them since 1990.
Over the last 20 years, leafy greens caused 363 outbreaks, resulting in 13,568 reported illnesses, the center said. That compared to berries, No. 10 on the list, which were associated with 25 outbreaks totaling 3,397 reported illnesses.
In all, the Top 10 resulted in more than 1,500 outbreaks, totaling nearly 50,000 reported illnesses, according to the Center, which added that most food-related illnesses don't get treated or reported.
"Millions of consumers are being made ill, hundreds of thousands hospitalized and thousands are dying each year from preventable foodborne illnesses," the study said. "Unfortunately, the FDA is saddled with outdated laws, and lacks the authority, tools and resources to fight unsafe food."
The severity of the illnesses ranged from minor stomach aches to death, the center said. With leafy greens such as lettuce, the top cause of illness were pathogens like E. coli, Norovirus and Salmonella in foods that were not properly washed.
Salmonella was also a chief culprit in egg, cheese and tomato-related illnesses, the study said, in cases when eggs are not washed or refrigerated properly, and when cheese is not processed properly. Salmonella can be difficult to remove from raw tomatoes without cooking, according to the study.
Unrefrigerated tuna deteriorates quickly, the study said, releasing harmful toxins, and improperly washed oysters are at risk of Norovirus.
More surprisingly, bacteria can also survive in ice cream, primarily from the Salmonella contamination of eggs, an important ingredient that is sometimes undercooked. Much of the blame goes to a 1994 outbreak that sickened thousands of ice cream lovers in 41 states, said the study.