Kale has higher pesticide residues than nearly all other produce found on supermarket shelves, according to the Environmental Working Group’s 2019 Dirty Dozen.
The EWG releases the Dirty Dozen as part of its annual Shopper’s Guide to Pesticides in Produce. It analyzes U.S. Department of Agriculture test data to identify which fruits and vegetables are most and least contaminated with pesticide residues. The Shopper’s Guide also includes the Clean Fifteen, a list of the fruits and vegetables with the lowest amount of residues.
On this year’s Dirty Dozen list, kale ranks third, after strawberries and spinach.
“We were surprised kale had so many pesticides on it, but the test results were unequivocal,” said Alexis Temkin, Ph.D., a toxicologist for the EWG. “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.”
In USDA’s recent round of tests, more than 92 percent of conventionally grown kale samples had at least two or more pesticide residues. Some samples contained residues from as many as 18 different pesticides.
Although kale has become more popular in the past decade, it hasn’t been included in USDA’s regular produce tests. Kale ranked eighth on the 2009 Dirty Dozen, the last year for which there was testing data.
In the latest tests, almost 60 percent of the kale samples tested positive for DCPA, or Dacthal, which the U.S. Environmental Protection Agency has classified as a possible human carcinogen. The pesticide has been banned for use on crops in the European Union since 2009.
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.
Nearly 70 percent of the conventionally-grown produce sold in the U.S. comes with pesticide residues, the EWG’s analysis found.
“The main route of pesticide exposure for most Americans who do not live or work on or near farms is through their diet,” said Carla Burns, research analyst for the EWG. “Studies have shown that eating fruits and vegetables free of pesticides benefits health, and this is especially important for pregnant women and children.”
Since 2012, the American Academy of Pediatricians Council on Environmental Health has recommended that children’s exposure to pesticides should be limited because pesticide exposure during pregnancy and early childhood increases the risk of brain tumors, leukemia, neurological defects, and other birth defects.
USDA’s tests found 225 different pesticides and pesticide breakdown products on popular fruits and vegetables Americans. Before testing, all produce was thoroughly washed and peeled, just as consumers would prepare food at home, showing that simple washing doesn’t remove all pesticides.
“Even low levels of pesticide exposure can be harmful to children,” said Philip Landrigan, M.D., a pediatrician and epidemiologist. “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.”
Landrigan is one of the main authors of the 1993 National Academy of Sciences study “Pesticides in the Diets of Infants and Children.” The study led to the passage of the 1996 Food Quality Protection Act, which emphasized children’s health in the setting of safety standards for pesticides on foods.
The EWG recommends, when possible, consumers purchase organic produce on the Dirty Dozen list. When organic versions aren’t available or not affordable, the EWG advises consumers to continue eating fresh produce, even if conventionally grown.
“The health benefits of a diet rich in fruits and vegetables outweigh the risks of pesticide exposure,” Burns said.
Other key findings from the EWG’s 2019 guide:
- More than 90 percent of samples of strawberries, apples, cherries, spinach, nectarines, and kale tested positive for residues of two or more pesticides.
- Kale and spinach samples had, on average, 10 to 80 percent more pesticide residue by weight than any other crop.
- Avocados and sweet corn were the cleanest. Less than 1 percent of samples showed any detectable pesticides.
- More than 70 percent of fruit and vegetable samples on the Clean Fifteen list had no pesticide residues.
- Multiple pesticide residues are rare on Clean Fifteen vegetables. Only 6 percent of Clean Fifteen fruit and vegetable samples had two or more pesticides.
- This year the EWG has expanded the Dirty Dozen list to include hot peppers, which don’t meet its ranking criteria but were found to be contaminated with insecticides toxic to the human nervous system.
The guide, released every year since 2004, ranks the pesticide contamination of 47 popular fruits and vegetables. It’s based on results of more than 40,900 samples of produce tested by the U.S. Department of Agriculture and the U.S. Food and Drug Administration.