The Dirty Dozen list of produce items with the highest pesticide residues that comes out annually included kale this year — the first time in a decade that the beloved leafy green has made the list.
Strawberries and spinach topped the ranking, respectively, while kale came in third.
The Environmental Working Group (EWG) bases its list on yearly reports released by the U.S. Department of Agriculture’s Pesticide Data Program. It ranks produce items with the most pesticide residue levels, and includes the “Clean Fifteen” list of items with the least amounts of contaminants.
As part of the USDA’s testing, more than 92 percent of conventionally grown kale samples demonstrated at least two or more pesticide residues. Some had residue from as many as 18 different pesticides.
Nearly 60 percent of kale samples tested positive for DCPA, or Dacthal, which the Environmental Protection Agency (EPA) has long classified as a possible human carcinogen. The pesticide has been prohibited for use on crops in the European Union since 2009. In recent EWG-initiated evaluations of kale from grocery stores, two of the eight samples had Dacthal residue similar to levels reported by the USDA.
“We were surprised kale had so many pesticides on it, but the test results were unequivocal,” Alexis Temkin, PhD, a toxicologist with EWG, said in a statement. “Fruits and vegetables are an important part of everyone’s diet, and when it comes to some conventionally grown produce items, such as kale, choosing organic may be a better option.”
Kale wasn’t included in regular USDA tests despite its popularity in recent years. The last year it was ranked based on testing data was in 2009, when it came in eighth on the 2009 Dirty Dozen list.
Recent EWG-commissioned tests of kale from grocery stores found that on two of eight samples, Dacthal residues were comparable to the average level reported by the USDA.
More than 99 percent of produce samples tested had acceptable levels of pesticide residues, according to federal standards. The EWG contends that the federal standards are insufficient. The EWG says almost 70 percent of conventionally grown produce that’s sold in the United States includes pesticide residues.
USDA tests found 225 different pesticides on popular fruits and veggies after they were washed.
The American Academy of Pediatrics Council on Environmental Health encourages limiting children’s exposure to pesticides, as exposure during pregnancy and early childhood can boost the risk of brain tumors, leukemia, neurodevelopmental defects, and other adverse birth outcomes.
“Even low levels of pesticide exposure can be harmful to children,” said Dr. Philip Landrigan, a world-renowned pediatrician and epidemiologist, said in an EWG statement. “When possible, parents and caregivers should take steps to lower children’s exposures to pesticides while still feeding them diets rich in healthy fruits and vegetables.”
Despite the dangers according to the EWG, Tamika Sims, PhD, director of food technology communications at the International Food Information Council Foundation, said she wasn’t surprised by popular snack fruits for kids, such as strawberries, apples, and grapes, that landed on the Dirty Dozen list.
“This tactic is used to send parents into an unwarranted frenzy,” Sims told Healthline.
Sims said that pesticide levels were safe on conventional and organically grown kale.
“Potential residues on either type of produce are in minute amounts that are not linked to any adverse health effects,” Sims said. She explained that the USDA’s Agricultural Marketing Service has issued reports confirming that overall pesticide chemical residues found on foods are at levels below the tolerances established by the EPA. As such, they don’t pose a safety concern, Sims added.
Sharon Palmer, RDN, a registered dietitian nutritionist from California, told Healthline the “cocktail effect” of combined pesticides on human health isn’t well understood.
“While we don’t know enough about the impact of pesticides on human health, some studies suggest that there may be risks,” she said. “But the most important thing is to eat more fruits and vegetables … period! There is no debate about the health benefits of eating more fruits and vegetables — conventionally grown, organically grown, frozen, canned — all forms.”
“The Dirty Dozen list is meant to guide people on which produce to purchase in organic form if they are concerned about pesticide residues,” Palmer added.
Sims advised washing produce with water, and said that’s enough to make produce safe.
Stephanie McKercher, RD, a Colorado-based registered dietitian, encourages people to try to buy organic items on the Dirty Dozen list when they can, but said that conventional produce is still a good choice.
“Buying organic isn’t accessible to everyone and that’s OK,” McKercher told Healthline.
She hopes the list doesn’t dissuade people from enjoying fruits and veggies — especially kale.
“Kale may be on the Dirty Dozen list, but it’s still an incredibly healthy food,” she explained. “Kale is a rich source of vitamins, minerals, antioxidants, and gut-boosting fiber.”
“Ultimately, my recommendation is to eat a variety of colorful fruits and vegetables whether or not they’re on the Dirty Dozen list,” McKercher noted.
“Keep eating kale,” Palmer added. “It might be a good idea to purchase this in its organic form, or from a local farmer at your farmers market who you trust. Best yet — grow it yourself. It’s a very easy vegetable to grow in a very small space — you can harvest leaves, and it keeps growing back, so a few plants can feed you for a long time.”