A recent study released by the Centers for Disease Control and Prevention fingered produce as the leading cause of food poisoning in the U.S. The study revealed that more than meat, poultry or fish, fruits and vegetables were the No. 1 source of food-borne illness over the 10-year period of the study (although more deaths were attributed to contaminated poultry).

Nearly half of all food poisonings were attributed to produce, the study showed.

Melons pose a particular hazard, according to Michael Doyle, director of the Center for Food Safety at the University of Georgia, because of the cracks and grooves on the skin. That applies to other fruits and vegetables, too.

In the CDC's study, leafy greens like lettuce and spinach were revealed as the worst culprits for food poisoning in the study period, between 1998 and 2008.

Salad greens marked "washed and ready to eat" or "triple-washed" remain an area of debate among food safety experts.

Some experts contend that the triple-washing with chlorine that takes place during processing is enough to kill what bacteria can be killed, and advise against washing bagged greens because the risk of cross-contamination in the home kitchen is a greater concern.

A 2010 study by the Consumers Union, which publishes Consumer Reports, concludes that consumers should wash all bagged or boxed lettuce and greens - even those marked prewashed or triple-washed - before consuming.

Despite his concerns, Doyle said the chances of getting ill from eating bagged lettuce, whether washed or not, remains fairly small.

"The reality of it is, the odds are in your favor," he said, noting that less than 1 percent of bagged salad greens are contaminated. "But even if it was one-tenth of a percent, when you multiply that times billions of bags sold, it's still a significant number," Doyle added.