"One contaminated head of lettuce or spinach thrown into a washing tank sees the pathogen in the wash water," Klein said. "And that spreads to an entire day's production of leafy greens."
The CSPI reported 352 outbreaks involving 11,163 cases of illness due to eggs contaminated primarily with salmonella, a bacteria that often causes diarrhea.
If eggs are not contaminated with salmonella before it is formed in a chicken, then undercooking, allowing the eggs to sit at room temperature, or cross contamination in the home or in a restaurant are a few of the major ways in which eggs can cause illness, according to Keith-Thomas Ayoob, an associate professor in the department of pediatrics at the Albert Einstein College of Medicine in New York City.
The report noted that prisons, restaurants and catered events were a few of the primary egg-related illness offenders.
"Eggs can have microscopic cracks too," which could allow for contamination after the egg is produced but before it is broken and used, Ayoob noted.
Still, Ayoob said eggs are generally safe foods and the chances of getting salmonella from an egg that has been properly stored and cooked is about one in 20,000.
Tuna fish was linked to 268 outbreaks and 2341 illnesses, according to the CSPI report.
The most common complaint was scombroid illness due to scombroid toxins, which are linked to fresh water fish and can occur in tuna that is left in a warm place too long. Side effects of ingesting scombroid toxins include flushing, nausea and cramps.
"Scombroid toxin is more likely in fresh or raw tuna than in processed varieties, such as canned tuna," said Caroline Smith DeWaal, food safety director for the Center for Science in the Public Interest and another author of the report. "Scombroid toxin can't be cooked away. The toxin may still be in cooked fish."
Ayoob pointed out that outbreaks associated with tuna could have other elements such as rancid mayonnaise in tuna salads. If, for example, tuna is purchased from a store or deli, it may have been sitting out at room temperature, allowing toxins and bacteria to accumulate.
This salt-water delicacy was the cause of 132 outbreaks and 3,409 reported illnesses, the CSPI report said.
"How much of that was eaten raw? If it's raw, you're on your own there," since the risks of eating raw or undercooked foods, including seafood, are well known, Ayoob said.
According to the CSPI findings, most of the oyster outbreaks occurred in restaurants and the most common pathogens were norovirus and vibrio. Norovirus, which causes acute stomach distress including vomiting, diarrhea and cramps, is related to poor food handling but it is also water-borne, which makes oysters particularly vulnerable to the virus.
Vibrio, a bacterium in the same family as cholera, is less common than Norovirus but more dangerous.
"[Oysters are] not consumed by many, but they do cause a large number of outbreaks and when those outbreaks occur, they can be large," DeWaal said.
It may seem impossible to get sick from this most basic, starchy root, but potatoes caused 108 outbreaks between 1990 and 2006, resulting in 3,695 cases of illness.
However, DeWaal noted that the problem, typically, is not the potato itself. Instead, cross contamination during food preparation is a likely source of blame since potatoes are a component of many recipes rather than a stand-alone food.