Apples again have the dubious honor of nabbing the top spot on the ''Dirty Dozen'' list of produce with unacceptable pesticide residues, issued by the Environmental Working Group.

EWG has also issued its updated "Clean Fifteen" list of produce least likely to be tainted with pesticides.

For the first time, the group also tested prepared baby food consisting of green beans, pears, and sweet potatoes. Its evaluation shows that some green bean and pear samples had pesticide residues, while sweet potatoes had virtually no detectable residues.

"Our advice to consumers is to choose the organic version of the fruits and vegetables on the dirty dozen list," Johanna Congleton, PhD, MSPH, an EWG senior scientist, tells WebMD.

While EWG scientists prefer organic versions of some produce, they do concede that ''eating commercially grown produce is better than not eating fruits and vegetables at all."

Another expert not involved in the report has some criticisms. "Their rankings are just very arbitrary," says Carl K. Winter, PhD, director of the FoodSafe program and an extension food toxicologist at the University of California, Davis.

He reviewed the findings for WebMD. "I think consumers should eat lots of fruits and vegetables, whether organic or conventional," Winter says, and there is no reason to fear these foods.
Dirty Dozen, 2012 Version

Besides apples, 11 other fruits and vegetables -- in order of the amount of pesticide residues, from more to less -- earned a spot on the Dirty Dozen list:

    Celery
    Sweet bell peppers
    Peaches
    Strawberries
    Nectarines (imported)
    Grapes
    Spinach
    Lettuce
    Cucumbers
    Blueberries (domestic)
    Potatoes

This year, EWG scientists added a "Plus" category to highlight two crops -- green beans and leafy greens such as kale and collard greens. They did not meet the criteria typically used for the Dirty Dozen list but were commonly contaminated with highly toxic organophosphate insecticides.

These insecticides, Congleton tells WebMD, are toxic to the nervous system. They have largely been removed from agriculture over the past decade. But they are not banned, so they still sometimes show up on crops.

According to EWG, pesticide exposure is linked with a range of other health problems, including hormone disruption, cancer, brain toxicity, and skin, eye, and lung irritation.
Clean Fifteen, 2012 Version

Making the updated "Clean Fifteen" list because they were found to be lowest in pesticides are:

    Onions
    Sweet corn
    Pineapples
    Avocado
    Cabbage
    Sweet peas
    Asparagus
    Mangoes
    Eggplant
    Kiwi
    Cantaloupe (domestic)
    Sweet potatoes
    Grapefruit
    Watermelon
    Mushrooms

Produce & Pesticides: Baby Foods

In the baby food evaluation, green beans tested positive for five pesticides. The evaluation of pears found 92% positive for at least one pesticide residue.

Sweet potatoes came up cleanest.
Making the Lists: Methods

The EWG has issued the lists for the past eight years. EWG scientists used pesticide testing data generated by USDA and FDA scientists to create the lists. In most studies, produce was tested after it was washed or peeled.