We've heard it all before: Load up on fruits and vegetables to boost your health. But pesticide residues have been tied to health risks, which is why the Environmental Working Group has reviewed USDA and FDA testing data to come up with its eighth annual "Dirty Dozen" list to let consumers know which foods are most commonly contaminated with pesticides.

According to the group, the latest round of government tests found pesticide residues on 68 percent of food samples. Will one of these foods be in your dinner?

Keep clicking to see which produce item earned the top spot on the Environmental Working Group's 2012 "Dirty Dozen" list.

Of potatoes tested, 91 percent contained one or more pesticides.

Blueberries are a popular fruit because they're high in antioxidants which have been tied to protective health benefits. In total, domestic blueberries tested positive for 42 different pesticide residues, and 73 percent of the blueberries contained two or more pesticides.

One cucumber sample contained 10 different types of pesticide, the EWG said.

Lettuce is one of the most likely vegetables to retain pesticide contamination. Tested samples of the salad and sandwich staple contained 78 different pesticides.

Are you eating spinach to stay strong like cartoon characters of old? The group found 88 percent of spinach samples it tested contained one or more pesticides.

Grapes had up to 15 pesticides detected on a single sample, the EWG found. As a category, grapes had more types of pesticides than any other produce, with 64 different chemicals.

Every sample of imported nectarines the USDA tested contained at least one pesticide.

Strawberries earned the fifth spot on the "Dirty Dozen" list because on average, the traditional summer fruit contained three pesticide residues. A single strawberry sample contained 13 different types of pesticides, according to the group.

Out of all peaches tested, 96 percent contained traces of one or more pesticides.

The EWG found celery samples to be highly contaminated, testing positive for 57 different pesticides. In all, 96 percent of celery samples tested positive for one or more pesticides.

While many adults and kids eat an apple daily to "keep the doctor away," the group found 98 percent of apples they tested contained pesticides. In fact, 93 percent of apples contained two or more pesticides, helping the popular fruit earn the top spot on the Environmental Working Group's "Dirty Dozen" list.

This year the Environmental Working Group expanded it's "Dirty Dozen" list to highlight green beans and leafy greens (kale and collard greens) because the vegetables did not meet traditional criteria to make the original list, but the group said they were "commonly contaminated with highly toxic organophosphate insecticides."

The insectisides have been tied to toxic nervous system effects and have been largely removed from crops over the past decade, however the EWG says they are not banned and still show up on these vegetables.

To find out which fruits and veggies were part of the group's "Clean 15" list of least contaminated produce, visit the Environmental Working Group.