1. Onions

2. Sweet corn

3. Pineapples

4. Avocado

5. Cabbage

6. Sweet peas

7. Asparagus

8. Mangoes

9. Eggplant

10. Kiwi

11. Domestic cantaloupe

12. Sweet potatoes

13. Grapefruit

14. Watermelon

15. Mushrooms

Although some switched spots within the ranks, the fruits and vegetables included on the lists stayed fairly consistent from the 2011 report.

The EWG report is based on pesticide residue data collected by the U.S. Department of Agriculture and the Food and Drug Administration, which tested samples as they normally would be eaten -- after being washed or peeled.

The chronic health effects of pesticide intake have not been widely studied, but Chensheng Lu, an associate professor of environmental exposure biology at the Harvard School of Public Health, said the toxins appear to be connected to a prevalence of diseases, including cancer. And some studies suggest pesticide intake, especially in the prenatal stage, can cause neurological developmental problems in infants, Lu said.

"Knowing that this chemical is designed to kill (certain) organisms, you have to be careful ingesting it," he said.

With the release of this list, the EWG suggests consumers reduce their exposure to pesticides as much as possible by purchasing organic versions of the Dirty Dozen. Organic produce is grown using materials of plant or animal origin, instead of chemicals.