To come up with the "Clean 15" and "Dirty Dozen" lists, EWG scientists focus on 48 popular fruits and vegetables and base their rankings on an analysis of 32,000 samples tested by the U.S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA).
To rank produce, EWG analysts use six metrics, including the total number of pesticides detected on a crop and the percent of samples tested with detectable pesticides. In the latest report, 65 percent of the samples analyzed tested positive for pesticide residues.
But the report goes beyond listing foods with the most pesticide residues and charges the U.S. Environmental Protect Agency (EPA) with failing to comply with the Congressionally mandated Food Quality Protection Act of 1996, legislation designed to to warn Americans of the risk of eating foods containing chemical pesticides.
"EWG's Shopper's Guide helps people find conventional fruits and vegetables with low concentrations of pesticide residues," says Sonya Lunder, EWG's senior analyst and principle author of the report. "If a particular item is likely to be high in pesticides, people can go for organic."
Related: 6 Foods Where Organic Matters Most
Dirty Dozen Plus
Nonorganic apples regularly to the EWG's Shopper's Guide to Pesticides in Produce report. As of 2015 the beloved fruit had earned the unfavorable spot five years running.
Kale, collard greens, and hot peppers were frequently contaminated with insecticides that are particularly toxic to human health, prompting their "Dirty Dozen Plus" status.
8. Sweet bell peppers
10. Cherry Tomatoes
11. Snap Peas (Imported)
+ Hot Peppers
+ Kale/Collard Greens
It's not all bad news! These produce picks contained the lowest pesticide levels.
2. Sweet Corn
5. Sweet Peas (Frozen)
15. Sweet Potatoes
Other Important Findings:
Every sample of imported nectarines and 99 percent of apple samples tested positive for at least one pesticide residue.
The average potato had more pesticides by weight than any other food.
A single grape tested positive for 15 pesticides.
Single samples of celery, cherry tomatoes, imported snap peas, and strawberries tested positive for 13 different pesticides apiece.
Only 1 percent of avocado samples showed any detectable pesticides.
89 percent of pineapples, 82 percent of kiwi, 80 percent of papayas, 88 percent of mango, and 61 percent of cantaloupe had no residues.
Related: "Extreme" Levels Of Roundup Detected In Food
"For decades, various toxic pesticides were claimed to be 'safe' … until they weren't, and were either banned or phased out because they posed risks to people," says Lunder. "While regulators and scientists debate these and other controversies about pesticide safety, EWG will continue drawing attention to the fruits and vegetables with the highest pesticide loads.