Nancy Cervone doesn't worry too much about food contamination, and she certainly would never consider herself a "germaphobe."

But when the Stow, Ohio, resident spotted a mound of cantaloupes on sale at the grocery store recently, she couldn't help but think about the illnesses linked to the melons in the summer of 2011.

"Unfortunately, every time I now eat cantaloupe, I think about the food poisoning outbreaks," she said.

Cervone's concerns have real merit.

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 foodborne 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.

Cantaloupes, especially, can harbor bacteria due to their rough, webbed outer skin. Cantaloupes require a good scrubbing under cold running water before they are sliced, otherwise the bacteria on the outside of the skin will be carried inside to the flesh with the first swipe of a knife.

Doyle said the more cracks and grooves on the skin of a fruit or vegetable, the more easily bacteria can hide. Melons also have a neutral pH, so they offer a perfect growing environment for bacteria.

The problem of contaminated melons is often made worse by grocery stores that sell cut pieces, but often don't store them in a cold enough environment.

Doyle recalls walking into an upscale grocery store in South Carolina one summer, where a metal tank with ice in the bottom was filled with containers of cut melon. The bottom inch of the containers was inside the ice, leaving the majority of the melon in an environment warm enough for bacteria to multiply rapidly.

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

Cervone said she has the mental debate over to-wash-or-not-to-wash every time she grabs a handful of bagged spinach for a salad.

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 pre-washed or triple-washed -- before consuming.

The agency tested bags of washed lettuces and found that while they may not be contaminated with E. coli, listeria or salmonella, 39 percent of all product samples had bacteria that are common indicators of poor sanitation and fecal contamination, and exceeded acceptable limits on total coliforms.

Doyle goes one step further -- he says not to buy bagged greens at all. He advises buying whole heads of lettuce or greens, removing the outer surface layers where bacteria is most likely to be present, and then washing the greens under cold running water.

Doyle has conducted studies that show the cutting and bagging of lettuce in processing plants can actually trap bacteria inside the lettuce leaves, meaning that no amount of scrubbing or washing will ever get rid of the germs. If greens are cut before they are washed -- as they commonly are during processing -- the bacteria become internalized by the leaves, trapping the germs inside the produce.

Then, it's not a question of what's on the leaves, but what's in the leaves. At that point, only cooking can kill the germs, and few salad greens are cooked before eating.

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.

As risky as bagged greens can be, Doyle said an even greater concern should be the consumption of raw sprouts like bean and alfalfa.

He believes the only reason they weren't first on the list of illness-causing produce in the CDC study is that folks just don't eat nearly as many of them as they do items like lettuce, tomatoes or melon.

He said sprouts, due to their high levels of contamination, should never be consumed raw.

E. coli, salmonella or listeria often are present in very low numbers on seeds for sprouts, but their growing conditions create the perfect Petri dish, Doyle explained.

"When we put the seeds into a vat of water to grow the sprouts, at the right temperature, and add nutrients into the water with lots of moisture, it's the best growing condition for bacteria," he said.

Sprouts' contamination can be so complete, it is nearly impossible to wash the germs away, making cooking the only safe option, he said.

Doyle said part of the problem is the changes in our eating habits, which includes more raw foods. In Asian cuisine, for example, bean sprouts were always cooked before being eaten, but now plenty of folks will eat raw sprouts of all varieties on salads and sandwiches.

The same is true for greens like spinach.

"When I was growing up, we would have never thought about eating raw spinach. Spinach was always cooked with bacon and vinegar. We never thought about eating it raw; that was for rabbits, not for people," Doyle added.

Despite the problems, there's no reason not to eat plenty of fresh produce. It's just important to follow safe handling and preparation practices.

Always wash produce, and hands too. Cold water and a good scrubbing will help to eliminate bacteria.

10 tips for safer produce

Here are 10 tips, gathered from a variety of food safety sources, for handling produce safely: