The top produce items among its “Clean Fifteen” include avocados, sweet corn, pineapples, frozen sweet peas and onions.
In the report, EWG scientists specifically highlighted that nearly 60 percent of kale samples sold in the United States were contaminated with DCPA (or Dacthal), which the Environmental Protection Agency first classified as a possible carcinogen in 1995.
"The EPA's 1995 classification of it as a possible carcinogen noted increases in liver and thyroid tumors," toxicologist Alexis Temkin wrote in a statement for EWG. "Dacthal can also cause other kinds of harm to the lungs, liver, kidney and thyroid."
According to the EWG, the European Union prohibited all uses of Dacthal back in 2009—the last time kale was on EWG’s “dirty” list—but the pesticide is still used on a variety of American crops, including broccoli, sweet potatoes, eggplant and turnips.
In 2016 alone, researchers said about 500,000 pounds of Dacthal were sprayed in the country.
But because kale is high in vitamins A and K as well as iron, and the vegetable has been known to help reduce risk of heart disease, researchers recommend that shoppers opt for organically grown kale.
Ultimately, EWG research analyst Carla Burns said in a news release, "the health benefits of a diet rich in fruits and vegetables outweigh the risks of pesticide exposure."